1 Booting the Linux/ppc kernel without Open Firmware
2 --------------------------------------------------
4 (c) 2005 Benjamin Herrenschmidt <benh at kernel.crashing.org>,
6 (c) 2005 Becky Bruce <becky.bruce at freescale.com>,
7 Freescale Semiconductor, FSL SOC and 32-bit additions
8 (c) 2006 MontaVista Software, Inc.
9 Flash chip node definition
15 1) Entry point for arch/powerpc
18 II - The DT block format
20 2) Device tree generalities
21 3) Device tree "structure" block
22 4) Device tree "strings" block
24 III - Required content of the device tree
25 1) Note about cells and address representation
26 2) Note about "compatible" properties
27 3) Note about "name" properties
28 4) Note about node and property names and character set
29 5) Required nodes and properties
33 d) the /memory node(s)
35 f) the /soc<SOCname> node
37 IV - "dtc", the device tree compiler
39 V - Recommendations for a bootloader
41 VI - System-on-a-chip devices and nodes
42 1) Defining child nodes of an SOC
43 2) Representing devices without a current OF specification
45 b) Gianfar-compatible ethernet nodes
47 d) Interrupt controllers
49 f) Freescale SOC USB controllers
50 g) Freescale SOC SEC Security Engines
51 h) Board Control and Status (BCSR)
52 i) Freescale QUICC Engine module (QE)
53 j) CFI or JEDEC memory-mapped NOR flash
54 k) Global Utilities Block
56 VII - Specifying interrupt information for devices
57 1) interrupts property
58 2) interrupt-parent property
59 3) OpenPIC Interrupt Controllers
60 4) ISA Interrupt Controllers
62 Appendix A - Sample SOC node for MPC8540
68 May 18, 2005: Rev 0.1 - Initial draft, no chapter III yet.
70 May 19, 2005: Rev 0.2 - Add chapter III and bits & pieces here or
71 clarifies the fact that a lot of things are
72 optional, the kernel only requires a very
73 small device tree, though it is encouraged
74 to provide an as complete one as possible.
76 May 24, 2005: Rev 0.3 - Precise that DT block has to be in RAM
78 - Define version 3 and new format version 16
79 for the DT block (version 16 needs kernel
80 patches, will be fwd separately).
81 String block now has a size, and full path
82 is replaced by unit name for more
84 linux,phandle is made optional, only nodes
85 that are referenced by other nodes need it.
86 "name" property is now automatically
87 deduced from the unit name
89 June 1, 2005: Rev 0.4 - Correct confusion between OF_DT_END and
90 OF_DT_END_NODE in structure definition.
91 - Change version 16 format to always align
92 property data to 4 bytes. Since tokens are
93 already aligned, that means no specific
94 required alignment between property size
95 and property data. The old style variable
96 alignment would make it impossible to do
97 "simple" insertion of properties using
98 memmove (thanks Milton for
99 noticing). Updated kernel patch as well
100 - Correct a few more alignment constraints
101 - Add a chapter about the device-tree
102 compiler and the textural representation of
103 the tree that can be "compiled" by dtc.
105 November 21, 2005: Rev 0.5
106 - Additions/generalizations for 32-bit
107 - Changed to reflect the new arch/powerpc
113 - Add some definitions of interrupt tree (simple/complex)
114 - Add some definitions for PCI host bridges
115 - Add some common address format examples
116 - Add definitions for standard properties and "compatible"
117 names for cells that are not already defined by the existing
119 - Compare FSL SOC use of PCI to standard and make sure no new
120 node definition required.
121 - Add more information about node definitions for SOC devices
122 that currently have no standard, like the FSL CPM.
128 During the recent development of the Linux/ppc64 kernel, and more
129 specifically, the addition of new platform types outside of the old
130 IBM pSeries/iSeries pair, it was decided to enforce some strict rules
131 regarding the kernel entry and bootloader <-> kernel interfaces, in
132 order to avoid the degeneration that had become the ppc32 kernel entry
133 point and the way a new platform should be added to the kernel. The
134 legacy iSeries platform breaks those rules as it predates this scheme,
135 but no new board support will be accepted in the main tree that
136 doesn't follows them properly. In addition, since the advent of the
137 arch/powerpc merged architecture for ppc32 and ppc64, new 32-bit
138 platforms and 32-bit platforms which move into arch/powerpc will be
139 required to use these rules as well.
141 The main requirement that will be defined in more detail below is
142 the presence of a device-tree whose format is defined after Open
143 Firmware specification. However, in order to make life easier
144 to embedded board vendors, the kernel doesn't require the device-tree
145 to represent every device in the system and only requires some nodes
146 and properties to be present. This will be described in detail in
147 section III, but, for example, the kernel does not require you to
148 create a node for every PCI device in the system. It is a requirement
149 to have a node for PCI host bridges in order to provide interrupt
150 routing informations and memory/IO ranges, among others. It is also
151 recommended to define nodes for on chip devices and other busses that
152 don't specifically fit in an existing OF specification. This creates a
153 great flexibility in the way the kernel can then probe those and match
154 drivers to device, without having to hard code all sorts of tables. It
155 also makes it more flexible for board vendors to do minor hardware
156 upgrades without significantly impacting the kernel code or cluttering
157 it with special cases.
160 1) Entry point for arch/powerpc
161 -------------------------------
163 There is one and one single entry point to the kernel, at the start
164 of the kernel image. That entry point supports two calling
167 a) Boot from Open Firmware. If your firmware is compatible
168 with Open Firmware (IEEE 1275) or provides an OF compatible
169 client interface API (support for "interpret" callback of
170 forth words isn't required), you can enter the kernel with:
172 r5 : OF callback pointer as defined by IEEE 1275
173 bindings to powerpc. Only the 32-bit client interface
174 is currently supported
176 r3, r4 : address & length of an initrd if any or 0
178 The MMU is either on or off; the kernel will run the
179 trampoline located in arch/powerpc/kernel/prom_init.c to
180 extract the device-tree and other information from open
181 firmware and build a flattened device-tree as described
182 in b). prom_init() will then re-enter the kernel using
183 the second method. This trampoline code runs in the
184 context of the firmware, which is supposed to handle all
185 exceptions during that time.
187 b) Direct entry with a flattened device-tree block. This entry
188 point is called by a) after the OF trampoline and can also be
189 called directly by a bootloader that does not support the Open
190 Firmware client interface. It is also used by "kexec" to
191 implement "hot" booting of a new kernel from a previous
192 running one. This method is what I will describe in more
193 details in this document, as method a) is simply standard Open
194 Firmware, and thus should be implemented according to the
195 various standard documents defining it and its binding to the
196 PowerPC platform. The entry point definition then becomes:
198 r3 : physical pointer to the device-tree block
199 (defined in chapter II) in RAM
201 r4 : physical pointer to the kernel itself. This is
202 used by the assembly code to properly disable the MMU
203 in case you are entering the kernel with MMU enabled
204 and a non-1:1 mapping.
206 r5 : NULL (as to differentiate with method a)
208 Note about SMP entry: Either your firmware puts your other
209 CPUs in some sleep loop or spin loop in ROM where you can get
210 them out via a soft reset or some other means, in which case
211 you don't need to care, or you'll have to enter the kernel
212 with all CPUs. The way to do that with method b) will be
213 described in a later revision of this document.
221 Board supports (platforms) are not exclusive config options. An
222 arbitrary set of board supports can be built in a single kernel
223 image. The kernel will "know" what set of functions to use for a
224 given platform based on the content of the device-tree. Thus, you
227 a) add your platform support as a _boolean_ option in
228 arch/powerpc/Kconfig, following the example of PPC_PSERIES,
229 PPC_PMAC and PPC_MAPLE. The later is probably a good
230 example of a board support to start from.
232 b) create your main platform file as
233 "arch/powerpc/platforms/myplatform/myboard_setup.c" and add it
234 to the Makefile under the condition of your CONFIG_
235 option. This file will define a structure of type "ppc_md"
236 containing the various callbacks that the generic code will
237 use to get to your platform specific code
239 c) Add a reference to your "ppc_md" structure in the
240 "machines" table in arch/powerpc/kernel/setup_64.c if you are
243 d) request and get assigned a platform number (see PLATFORM_*
244 constants in include/asm-powerpc/processor.h
246 32-bit embedded kernels:
248 Currently, board support is essentially an exclusive config option.
249 The kernel is configured for a single platform. Part of the reason
250 for this is to keep kernels on embedded systems small and efficient;
251 part of this is due to the fact the code is already that way. In the
252 future, a kernel may support multiple platforms, but only if the
253 platforms feature the same core architecture. A single kernel build
254 cannot support both configurations with Book E and configurations
255 with classic Powerpc architectures.
257 32-bit embedded platforms that are moved into arch/powerpc using a
258 flattened device tree should adopt the merged tree practice of
259 setting ppc_md up dynamically, even though the kernel is currently
260 built with support for only a single platform at a time. This allows
261 unification of the setup code, and will make it easier to go to a
262 multiple-platform-support model in the future.
264 NOTE: I believe the above will be true once Ben's done with the merge
265 of the boot sequences.... someone speak up if this is wrong!
267 To add a 32-bit embedded platform support, follow the instructions
268 for 64-bit platforms above, with the exception that the Kconfig
269 option should be set up such that the kernel builds exclusively for
270 the platform selected. The processor type for the platform should
271 enable another config option to select the specific board
274 NOTE: If Ben doesn't merge the setup files, may need to change this to
278 I will describe later the boot process and various callbacks that
279 your platform should implement.
282 II - The DT block format
283 ========================
286 This chapter defines the actual format of the flattened device-tree
287 passed to the kernel. The actual content of it and kernel requirements
288 are described later. You can find example of code manipulating that
289 format in various places, including arch/powerpc/kernel/prom_init.c
290 which will generate a flattened device-tree from the Open Firmware
291 representation, or the fs2dt utility which is part of the kexec tools
292 which will generate one from a filesystem representation. It is
293 expected that a bootloader like uboot provides a bit more support,
294 that will be discussed later as well.
296 Note: The block has to be in main memory. It has to be accessible in
297 both real mode and virtual mode with no mapping other than main
298 memory. If you are writing a simple flash bootloader, it should copy
299 the block to RAM before passing it to the kernel.
305 The kernel is entered with r3 pointing to an area of memory that is
306 roughly described in include/asm-powerpc/prom.h by the structure
309 struct boot_param_header {
310 u32 magic; /* magic word OF_DT_HEADER */
311 u32 totalsize; /* total size of DT block */
312 u32 off_dt_struct; /* offset to structure */
313 u32 off_dt_strings; /* offset to strings */
314 u32 off_mem_rsvmap; /* offset to memory reserve map
316 u32 version; /* format version */
317 u32 last_comp_version; /* last compatible version */
319 /* version 2 fields below */
320 u32 boot_cpuid_phys; /* Which physical CPU id we're
322 /* version 3 fields below */
323 u32 size_dt_strings; /* size of the strings block */
325 /* version 17 fields below */
326 u32 size_dt_struct; /* size of the DT structure block */
329 Along with the constants:
331 /* Definitions used by the flattened device tree */
332 #define OF_DT_HEADER 0xd00dfeed /* 4: version,
334 #define OF_DT_BEGIN_NODE 0x1 /* Start node: full name
336 #define OF_DT_END_NODE 0x2 /* End node */
337 #define OF_DT_PROP 0x3 /* Property: name off,
339 #define OF_DT_END 0x9
341 All values in this header are in big endian format, the various
342 fields in this header are defined more precisely below. All
343 "offset" values are in bytes from the start of the header; that is
344 from the value of r3.
348 This is a magic value that "marks" the beginning of the
349 device-tree block header. It contains the value 0xd00dfeed and is
350 defined by the constant OF_DT_HEADER
354 This is the total size of the DT block including the header. The
355 "DT" block should enclose all data structures defined in this
356 chapter (who are pointed to by offsets in this header). That is,
357 the device-tree structure, strings, and the memory reserve map.
361 This is an offset from the beginning of the header to the start
362 of the "structure" part the device tree. (see 2) device tree)
366 This is an offset from the beginning of the header to the start
367 of the "strings" part of the device-tree
371 This is an offset from the beginning of the header to the start
372 of the reserved memory map. This map is a list of pairs of 64-
373 bit integers. Each pair is a physical address and a size. The
374 list is terminated by an entry of size 0. This map provides the
375 kernel with a list of physical memory areas that are "reserved"
376 and thus not to be used for memory allocations, especially during
377 early initialization. The kernel needs to allocate memory during
378 boot for things like un-flattening the device-tree, allocating an
379 MMU hash table, etc... Those allocations must be done in such a
380 way to avoid overriding critical things like, on Open Firmware
381 capable machines, the RTAS instance, or on some pSeries, the TCE
382 tables used for the iommu. Typically, the reserve map should
383 contain _at least_ this DT block itself (header,total_size). If
384 you are passing an initrd to the kernel, you should reserve it as
385 well. You do not need to reserve the kernel image itself. The map
386 should be 64-bit aligned.
390 This is the version of this structure. Version 1 stops
391 here. Version 2 adds an additional field boot_cpuid_phys.
392 Version 3 adds the size of the strings block, allowing the kernel
393 to reallocate it easily at boot and free up the unused flattened
394 structure after expansion. Version 16 introduces a new more
395 "compact" format for the tree itself that is however not backward
396 compatible. Version 17 adds an additional field, size_dt_struct,
397 allowing it to be reallocated or moved more easily (this is
398 particularly useful for bootloaders which need to make
399 adjustments to a device tree based on probed information). You
400 should always generate a structure of the highest version defined
401 at the time of your implementation. Currently that is version 17,
402 unless you explicitly aim at being backward compatible.
406 Last compatible version. This indicates down to what version of
407 the DT block you are backward compatible. For example, version 2
408 is backward compatible with version 1 (that is, a kernel build
409 for version 1 will be able to boot with a version 2 format). You
410 should put a 1 in this field if you generate a device tree of
411 version 1 to 3, or 16 if you generate a tree of version 16 or 17
412 using the new unit name format.
416 This field only exist on version 2 headers. It indicate which
417 physical CPU ID is calling the kernel entry point. This is used,
418 among others, by kexec. If you are on an SMP system, this value
419 should match the content of the "reg" property of the CPU node in
420 the device-tree corresponding to the CPU calling the kernel entry
421 point (see further chapters for more informations on the required
422 device-tree contents)
426 This field only exists on version 3 and later headers. It
427 gives the size of the "strings" section of the device tree (which
428 starts at the offset given by off_dt_strings).
432 This field only exists on version 17 and later headers. It gives
433 the size of the "structure" section of the device tree (which
434 starts at the offset given by off_dt_struct).
436 So the typical layout of a DT block (though the various parts don't
437 need to be in that order) looks like this (addresses go from top to
441 ------------------------------
442 r3 -> | struct boot_param_header |
443 ------------------------------
444 | (alignment gap) (*) |
445 ------------------------------
446 | memory reserve map |
447 ------------------------------
449 ------------------------------
451 | device-tree structure |
453 ------------------------------
455 ------------------------------
457 | device-tree strings |
459 -----> ------------------------------
464 (*) The alignment gaps are not necessarily present; their presence
465 and size are dependent on the various alignment requirements of
466 the individual data blocks.
469 2) Device tree generalities
470 ---------------------------
472 This device-tree itself is separated in two different blocks, a
473 structure block and a strings block. Both need to be aligned to a 4
476 First, let's quickly describe the device-tree concept before detailing
477 the storage format. This chapter does _not_ describe the detail of the
478 required types of nodes & properties for the kernel, this is done
479 later in chapter III.
481 The device-tree layout is strongly inherited from the definition of
482 the Open Firmware IEEE 1275 device-tree. It's basically a tree of
483 nodes, each node having two or more named properties. A property can
486 It is a tree, so each node has one and only one parent except for the
487 root node who has no parent.
489 A node has 2 names. The actual node name is generally contained in a
490 property of type "name" in the node property list whose value is a
491 zero terminated string and is mandatory for version 1 to 3 of the
492 format definition (as it is in Open Firmware). Version 16 makes it
493 optional as it can generate it from the unit name defined below.
495 There is also a "unit name" that is used to differentiate nodes with
496 the same name at the same level, it is usually made of the node
497 names, the "@" sign, and a "unit address", which definition is
498 specific to the bus type the node sits on.
500 The unit name doesn't exist as a property per-se but is included in
501 the device-tree structure. It is typically used to represent "path" in
502 the device-tree. More details about the actual format of these will be
505 The kernel powerpc generic code does not make any formal use of the
506 unit address (though some board support code may do) so the only real
507 requirement here for the unit address is to ensure uniqueness of
508 the node unit name at a given level of the tree. Nodes with no notion
509 of address and no possible sibling of the same name (like /memory or
510 /cpus) may omit the unit address in the context of this specification,
511 or use the "@0" default unit address. The unit name is used to define
512 a node "full path", which is the concatenation of all parent node
513 unit names separated with "/".
515 The root node doesn't have a defined name, and isn't required to have
516 a name property either if you are using version 3 or earlier of the
517 format. It also has no unit address (no @ symbol followed by a unit
518 address). The root node unit name is thus an empty string. The full
519 path to the root node is "/".
521 Every node which actually represents an actual device (that is, a node
522 which isn't only a virtual "container" for more nodes, like "/cpus"
523 is) is also required to have a "device_type" property indicating the
526 Finally, every node that can be referenced from a property in another
527 node is required to have a "linux,phandle" property. Real open
528 firmware implementations provide a unique "phandle" value for every
529 node that the "prom_init()" trampoline code turns into
530 "linux,phandle" properties. However, this is made optional if the
531 flattened device tree is used directly. An example of a node
532 referencing another node via "phandle" is when laying out the
533 interrupt tree which will be described in a further version of this
536 This "linux, phandle" property is a 32-bit value that uniquely
537 identifies a node. You are free to use whatever values or system of
538 values, internal pointers, or whatever to generate these, the only
539 requirement is that every node for which you provide that property has
540 a unique value for it.
542 Here is an example of a simple device-tree. In this example, an "o"
543 designates a node followed by the node unit name. Properties are
544 presented with their name followed by their content. "content"
545 represents an ASCII string (zero terminated) value, while <content>
546 represents a 32-bit hexadecimal value. The various nodes in this
547 example will be discussed in a later chapter. At this point, it is
548 only meant to give you a idea of what a device-tree looks like. I have
549 purposefully kept the "name" and "linux,phandle" properties which
550 aren't necessary in order to give you a better idea of what the tree
551 looks like in practice.
554 |- name = "device-tree"
555 |- model = "MyBoardName"
556 |- compatible = "MyBoardFamilyName"
557 |- #address-cells = <2>
559 |- linux,phandle = <0>
563 | | - linux,phandle = <1>
564 | | - #address-cells = <1>
565 | | - #size-cells = <0>
568 | |- name = "PowerPC,970"
569 | |- device_type = "cpu"
571 | |- clock-frequency = <5f5e1000>
573 | |- linux,phandle = <2>
577 | |- device_type = "memory"
578 | |- reg = <00000000 00000000 00000000 20000000>
579 | |- linux,phandle = <3>
583 |- bootargs = "root=/dev/sda2"
584 |- linux,phandle = <4>
586 This tree is almost a minimal tree. It pretty much contains the
587 minimal set of required nodes and properties to boot a linux kernel;
588 that is, some basic model informations at the root, the CPUs, and the
589 physical memory layout. It also includes misc information passed
590 through /chosen, like in this example, the platform type (mandatory)
591 and the kernel command line arguments (optional).
593 The /cpus/PowerPC,970@0/64-bit property is an example of a
594 property without a value. All other properties have a value. The
595 significance of the #address-cells and #size-cells properties will be
596 explained in chapter IV which defines precisely the required nodes and
597 properties and their content.
600 3) Device tree "structure" block
602 The structure of the device tree is a linearized tree structure. The
603 "OF_DT_BEGIN_NODE" token starts a new node, and the "OF_DT_END_NODE"
604 ends that node definition. Child nodes are simply defined before
605 "OF_DT_END_NODE" (that is nodes within the node). A 'token' is a 32
606 bit value. The tree has to be "finished" with a OF_DT_END token
608 Here's the basic structure of a single node:
610 * token OF_DT_BEGIN_NODE (that is 0x00000001)
611 * for version 1 to 3, this is the node full path as a zero
612 terminated string, starting with "/". For version 16 and later,
613 this is the node unit name only (or an empty string for the
615 * [align gap to next 4 bytes boundary]
617 * token OF_DT_PROP (that is 0x00000003)
618 * 32-bit value of property value size in bytes (or 0 if no
620 * 32-bit value of offset in string block of property name
621 * property value data if any
622 * [align gap to next 4 bytes boundary]
623 * [child nodes if any]
624 * token OF_DT_END_NODE (that is 0x00000002)
626 So the node content can be summarized as a start token, a full path,
627 a list of properties, a list of child nodes, and an end token. Every
628 child node is a full node structure itself as defined above.
630 NOTE: The above definition requires that all property definitions for
631 a particular node MUST precede any subnode definitions for that node.
632 Although the structure would not be ambiguous if properties and
633 subnodes were intermingled, the kernel parser requires that the
634 properties come first (up until at least 2.6.22). Any tools
635 manipulating a flattened tree must take care to preserve this
638 4) Device tree "strings" block
640 In order to save space, property names, which are generally redundant,
641 are stored separately in the "strings" block. This block is simply the
642 whole bunch of zero terminated strings for all property names
643 concatenated together. The device-tree property definitions in the
644 structure block will contain offset values from the beginning of the
648 III - Required content of the device tree
649 =========================================
651 WARNING: All "linux,*" properties defined in this document apply only
652 to a flattened device-tree. If your platform uses a real
653 implementation of Open Firmware or an implementation compatible with
654 the Open Firmware client interface, those properties will be created
655 by the trampoline code in the kernel's prom_init() file. For example,
656 that's where you'll have to add code to detect your board model and
657 set the platform number. However, when using the flattened device-tree
658 entry point, there is no prom_init() pass, and thus you have to
659 provide those properties yourself.
662 1) Note about cells and address representation
663 ----------------------------------------------
665 The general rule is documented in the various Open Firmware
666 documentations. If you choose to describe a bus with the device-tree
667 and there exist an OF bus binding, then you should follow the
668 specification. However, the kernel does not require every single
669 device or bus to be described by the device tree.
671 In general, the format of an address for a device is defined by the
672 parent bus type, based on the #address-cells and #size-cells
673 property. In the absence of such a property, the parent's parent
674 values are used, etc... The kernel requires the root node to have
675 those properties defining addresses format for devices directly mapped
676 on the processor bus.
678 Those 2 properties define 'cells' for representing an address and a
679 size. A "cell" is a 32-bit number. For example, if both contain 2
680 like the example tree given above, then an address and a size are both
681 composed of 2 cells, and each is a 64-bit number (cells are
682 concatenated and expected to be in big endian format). Another example
683 is the way Apple firmware defines them, with 2 cells for an address
684 and one cell for a size. Most 32-bit implementations should define
685 #address-cells and #size-cells to 1, which represents a 32-bit value.
686 Some 32-bit processors allow for physical addresses greater than 32
687 bits; these processors should define #address-cells as 2.
689 "reg" properties are always a tuple of the type "address size" where
690 the number of cells of address and size is specified by the bus
691 #address-cells and #size-cells. When a bus supports various address
692 spaces and other flags relative to a given address allocation (like
693 prefetchable, etc...) those flags are usually added to the top level
694 bits of the physical address. For example, a PCI physical address is
695 made of 3 cells, the bottom two containing the actual address itself
696 while the top cell contains address space indication, flags, and pci
697 bus & device numbers.
699 For busses that support dynamic allocation, it's the accepted practice
700 to then not provide the address in "reg" (keep it 0) though while
701 providing a flag indicating the address is dynamically allocated, and
702 then, to provide a separate "assigned-addresses" property that
703 contains the fully allocated addresses. See the PCI OF bindings for
706 In general, a simple bus with no address space bits and no dynamic
707 allocation is preferred if it reflects your hardware, as the existing
708 kernel address parsing functions will work out of the box. If you
709 define a bus type with a more complex address format, including things
710 like address space bits, you'll have to add a bus translator to the
711 prom_parse.c file of the recent kernels for your bus type.
713 The "reg" property only defines addresses and sizes (if #size-cells
714 is non-0) within a given bus. In order to translate addresses upward
715 (that is into parent bus addresses, and possibly into CPU physical
716 addresses), all busses must contain a "ranges" property. If the
717 "ranges" property is missing at a given level, it's assumed that
718 translation isn't possible. The format of the "ranges" property for a
721 bus address, parent bus address, size
723 "bus address" is in the format of the bus this bus node is defining,
724 that is, for a PCI bridge, it would be a PCI address. Thus, (bus
725 address, size) defines a range of addresses for child devices. "parent
726 bus address" is in the format of the parent bus of this bus. For
727 example, for a PCI host controller, that would be a CPU address. For a
728 PCI<->ISA bridge, that would be a PCI address. It defines the base
729 address in the parent bus where the beginning of that range is mapped.
731 For a new 64-bit powerpc board, I recommend either the 2/2 format or
732 Apple's 2/1 format which is slightly more compact since sizes usually
733 fit in a single 32-bit word. New 32-bit powerpc boards should use a
734 1/1 format, unless the processor supports physical addresses greater
735 than 32-bits, in which case a 2/1 format is recommended.
738 2) Note about "compatible" properties
739 -------------------------------------
741 These properties are optional, but recommended in devices and the root
742 node. The format of a "compatible" property is a list of concatenated
743 zero terminated strings. They allow a device to express its
744 compatibility with a family of similar devices, in some cases,
745 allowing a single driver to match against several devices regardless
746 of their actual names.
748 3) Note about "name" properties
749 -------------------------------
751 While earlier users of Open Firmware like OldWorld macintoshes tended
752 to use the actual device name for the "name" property, it's nowadays
753 considered a good practice to use a name that is closer to the device
754 class (often equal to device_type). For example, nowadays, ethernet
755 controllers are named "ethernet", an additional "model" property
756 defining precisely the chip type/model, and "compatible" property
757 defining the family in case a single driver can driver more than one
758 of these chips. However, the kernel doesn't generally put any
759 restriction on the "name" property; it is simply considered good
760 practice to follow the standard and its evolutions as closely as
763 Note also that the new format version 16 makes the "name" property
764 optional. If it's absent for a node, then the node's unit name is then
765 used to reconstruct the name. That is, the part of the unit name
766 before the "@" sign is used (or the entire unit name if no "@" sign
769 4) Note about node and property names and character set
770 -------------------------------------------------------
772 While open firmware provides more flexible usage of 8859-1, this
773 specification enforces more strict rules. Nodes and properties should
774 be comprised only of ASCII characters 'a' to 'z', '0' to
775 '9', ',', '.', '_', '+', '#', '?', and '-'. Node names additionally
776 allow uppercase characters 'A' to 'Z' (property names should be
777 lowercase. The fact that vendors like Apple don't respect this rule is
778 irrelevant here). Additionally, node and property names should always
779 begin with a character in the range 'a' to 'z' (or 'A' to 'Z' for node
782 The maximum number of characters for both nodes and property names
783 is 31. In the case of node names, this is only the leftmost part of
784 a unit name (the pure "name" property), it doesn't include the unit
785 address which can extend beyond that limit.
788 5) Required nodes and properties
789 --------------------------------
790 These are all that are currently required. However, it is strongly
791 recommended that you expose PCI host bridges as documented in the
792 PCI binding to open firmware, and your interrupt tree as documented
793 in OF interrupt tree specification.
797 The root node requires some properties to be present:
799 - model : this is your board name/model
800 - #address-cells : address representation for "root" devices
801 - #size-cells: the size representation for "root" devices
802 - device_type : This property shouldn't be necessary. However, if
803 you decide to create a device_type for your root node, make sure it
804 is _not_ "chrp" unless your platform is a pSeries or PAPR compliant
805 one for 64-bit, or a CHRP-type machine for 32-bit as this will
806 matched by the kernel this way.
808 Additionally, some recommended properties are:
810 - compatible : the board "family" generally finds its way here,
811 for example, if you have 2 board models with a similar layout,
812 that typically get driven by the same platform code in the
813 kernel, you would use a different "model" property but put a
814 value in "compatible". The kernel doesn't directly use that
815 value but it is generally useful.
817 The root node is also generally where you add additional properties
818 specific to your board like the serial number if any, that sort of
819 thing. It is recommended that if you add any "custom" property whose
820 name may clash with standard defined ones, you prefix them with your
821 vendor name and a comma.
825 This node is the parent of all individual CPU nodes. It doesn't
826 have any specific requirements, though it's generally good practice
829 #address-cells = <00000001>
830 #size-cells = <00000000>
832 This defines that the "address" for a CPU is a single cell, and has
833 no meaningful size. This is not necessary but the kernel will assume
834 that format when reading the "reg" properties of a CPU node, see
839 So under /cpus, you are supposed to create a node for every CPU on
840 the machine. There is no specific restriction on the name of the
841 CPU, though It's common practice to call it PowerPC,<name>. For
842 example, Apple uses PowerPC,G5 while IBM uses PowerPC,970FX.
846 - device_type : has to be "cpu"
847 - reg : This is the physical CPU number, it's a single 32-bit cell
848 and is also used as-is as the unit number for constructing the
849 unit name in the full path. For example, with 2 CPUs, you would
851 /cpus/PowerPC,970FX@0
852 /cpus/PowerPC,970FX@1
853 (unit addresses do not require leading zeroes)
854 - d-cache-block-size : one cell, L1 data cache block size in bytes (*)
855 - i-cache-block-size : one cell, L1 instruction cache block size in
857 - d-cache-size : one cell, size of L1 data cache in bytes
858 - i-cache-size : one cell, size of L1 instruction cache in bytes
860 (*) The cache "block" size is the size on which the cache management
861 instructions operate. Historically, this document used the cache
862 "line" size here which is incorrect. The kernel will prefer the cache
863 block size and will fallback to cache line size for backward
866 Recommended properties:
868 - timebase-frequency : a cell indicating the frequency of the
869 timebase in Hz. This is not directly used by the generic code,
870 but you are welcome to copy/paste the pSeries code for setting
871 the kernel timebase/decrementer calibration based on this
873 - clock-frequency : a cell indicating the CPU core clock frequency
874 in Hz. A new property will be defined for 64-bit values, but if
875 your frequency is < 4Ghz, one cell is enough. Here as well as
876 for the above, the common code doesn't use that property, but
877 you are welcome to re-use the pSeries or Maple one. A future
878 kernel version might provide a common function for this.
879 - d-cache-line-size : one cell, L1 data cache line size in bytes
880 if different from the block size
881 - i-cache-line-size : one cell, L1 instruction cache line size in
882 bytes if different from the block size
884 You are welcome to add any property you find relevant to your board,
885 like some information about the mechanism used to soft-reset the
886 CPUs. For example, Apple puts the GPIO number for CPU soft reset
887 lines in there as a "soft-reset" property since they start secondary
888 CPUs by soft-resetting them.
891 d) the /memory node(s)
893 To define the physical memory layout of your board, you should
894 create one or more memory node(s). You can either create a single
895 node with all memory ranges in its reg property, or you can create
896 several nodes, as you wish. The unit address (@ part) used for the
897 full path is the address of the first range of memory defined by a
898 given node. If you use a single memory node, this will typically be
903 - device_type : has to be "memory"
904 - reg : This property contains all the physical memory ranges of
905 your board. It's a list of addresses/sizes concatenated
906 together, with the number of cells of each defined by the
907 #address-cells and #size-cells of the root node. For example,
908 with both of these properties being 2 like in the example given
909 earlier, a 970 based machine with 6Gb of RAM could typically
910 have a "reg" property here that looks like:
912 00000000 00000000 00000000 80000000
913 00000001 00000000 00000001 00000000
915 That is a range starting at 0 of 0x80000000 bytes and a range
916 starting at 0x100000000 and of 0x100000000 bytes. You can see
917 that there is no memory covering the IO hole between 2Gb and
918 4Gb. Some vendors prefer splitting those ranges into smaller
919 segments, but the kernel doesn't care.
923 This node is a bit "special". Normally, that's where open firmware
924 puts some variable environment information, like the arguments, or
925 the default input/output devices.
927 This specification makes a few of these mandatory, but also defines
928 some linux-specific properties that would be normally constructed by
929 the prom_init() trampoline when booting with an OF client interface,
930 but that you have to provide yourself when using the flattened format.
932 Recommended properties:
934 - bootargs : This zero-terminated string is passed as the kernel
936 - linux,stdout-path : This is the full path to your standard
937 console device if any. Typically, if you have serial devices on
938 your board, you may want to put the full path to the one set as
939 the default console in the firmware here, for the kernel to pick
940 it up as its own default console. If you look at the function
941 set_preferred_console() in arch/ppc64/kernel/setup.c, you'll see
942 that the kernel tries to find out the default console and has
943 knowledge of various types like 8250 serial ports. You may want
944 to extend this function to add your own.
946 Note that u-boot creates and fills in the chosen node for platforms
949 (Note: a practice that is now obsolete was to include a property
950 under /chosen called interrupt-controller which had a phandle value
951 that pointed to the main interrupt controller)
953 f) the /soc<SOCname> node
955 This node is used to represent a system-on-a-chip (SOC) and must be
956 present if the processor is a SOC. The top-level soc node contains
957 information that is global to all devices on the SOC. The node name
958 should contain a unit address for the SOC, which is the base address
959 of the memory-mapped register set for the SOC. The name of an soc
960 node should start with "soc", and the remainder of the name should
961 represent the part number for the soc. For example, the MPC8540's
962 soc node would be called "soc8540".
966 - device_type : Should be "soc"
967 - ranges : Should be defined as specified in 1) to describe the
968 translation of SOC addresses for memory mapped SOC registers.
969 - bus-frequency: Contains the bus frequency for the SOC node.
970 Typically, the value of this field is filled in by the boot
974 Recommended properties:
976 - reg : This property defines the address and size of the
977 memory-mapped registers that are used for the SOC node itself.
978 It does not include the child device registers - these will be
979 defined inside each child node. The address specified in the
980 "reg" property should match the unit address of the SOC node.
981 - #address-cells : Address representation for "soc" devices. The
982 format of this field may vary depending on whether or not the
983 device registers are memory mapped. For memory mapped
984 registers, this field represents the number of cells needed to
985 represent the address of the registers. For SOCs that do not
986 use MMIO, a special address format should be defined that
987 contains enough cells to represent the required information.
988 See 1) above for more details on defining #address-cells.
989 - #size-cells : Size representation for "soc" devices
990 - #interrupt-cells : Defines the width of cells used to represent
991 interrupts. Typically this value is <2>, which includes a
992 32-bit number that represents the interrupt number, and a
993 32-bit number that represents the interrupt sense and level.
994 This field is only needed if the SOC contains an interrupt
997 The SOC node may contain child nodes for each SOC device that the
998 platform uses. Nodes should not be created for devices which exist
999 on the SOC but are not used by a particular platform. See chapter VI
1000 for more information on how to specify devices that are part of a SOC.
1002 Example SOC node for the MPC8540:
1005 #address-cells = <1>;
1007 #interrupt-cells = <2>;
1008 device_type = "soc";
1009 ranges = <00000000 e0000000 00100000>
1010 reg = <e0000000 00003000>;
1011 bus-frequency = <0>;
1016 IV - "dtc", the device tree compiler
1017 ====================================
1020 dtc source code can be found at
1021 <http://ozlabs.org/~dgibson/dtc/dtc.tar.gz>
1023 WARNING: This version is still in early development stage; the
1024 resulting device-tree "blobs" have not yet been validated with the
1025 kernel. The current generated bloc lacks a useful reserve map (it will
1026 be fixed to generate an empty one, it's up to the bootloader to fill
1027 it up) among others. The error handling needs work, bugs are lurking,
1030 dtc basically takes a device-tree in a given format and outputs a
1031 device-tree in another format. The currently supported formats are:
1036 - "dtb": "blob" format, that is a flattened device-tree block
1038 header all in a binary blob.
1039 - "dts": "source" format. This is a text file containing a
1040 "source" for a device-tree. The format is defined later in this
1042 - "fs" format. This is a representation equivalent to the
1043 output of /proc/device-tree, that is nodes are directories and
1044 properties are files
1049 - "dtb": "blob" format
1050 - "dts": "source" format
1051 - "asm": assembly language file. This is a file that can be
1052 sourced by gas to generate a device-tree "blob". That file can
1053 then simply be added to your Makefile. Additionally, the
1054 assembly file exports some symbols that can be used.
1057 The syntax of the dtc tool is
1059 dtc [-I <input-format>] [-O <output-format>]
1060 [-o output-filename] [-V output_version] input_filename
1063 The "output_version" defines what version of the "blob" format will be
1064 generated. Supported versions are 1,2,3 and 16. The default is
1065 currently version 3 but that may change in the future to version 16.
1067 Additionally, dtc performs various sanity checks on the tree, like the
1068 uniqueness of linux, phandle properties, validity of strings, etc...
1070 The format of the .dts "source" file is "C" like, supports C and C++
1076 The above is the "device-tree" definition. It's the only statement
1077 supported currently at the toplevel.
1080 property1 = "string_value"; /* define a property containing a 0
1084 property2 = <1234abcd>; /* define a property containing a
1085 * numerical 32-bit value (hexadecimal)
1088 property3 = <12345678 12345678 deadbeef>;
1089 /* define a property containing 3
1090 * numerical 32-bit values (cells) in
1093 property4 = [0a 0b 0c 0d de ea ad be ef];
1094 /* define a property whose content is
1095 * an arbitrary array of bytes
1098 childnode@addresss { /* define a child node named "childnode"
1099 * whose unit name is "childnode at
1103 childprop = "hello\n"; /* define a property "childprop" of
1104 * childnode (in this case, a string)
1109 Nodes can contain other nodes etc... thus defining the hierarchical
1110 structure of the tree.
1112 Strings support common escape sequences from C: "\n", "\t", "\r",
1113 "\(octal value)", "\x(hex value)".
1115 It is also suggested that you pipe your source file through cpp (gcc
1116 preprocessor) so you can use #include's, #define for constants, etc...
1118 Finally, various options are planned but not yet implemented, like
1119 automatic generation of phandles, labels (exported to the asm file so
1120 you can point to a property content and change it easily from whatever
1121 you link the device-tree with), label or path instead of numeric value
1122 in some cells to "point" to a node (replaced by a phandle at compile
1123 time), export of reserve map address to the asm file, ability to
1124 specify reserve map content at compile time, etc...
1126 We may provide a .h include file with common definitions of that
1127 proves useful for some properties (like building PCI properties or
1128 interrupt maps) though it may be better to add a notion of struct
1129 definitions to the compiler...
1132 V - Recommendations for a bootloader
1133 ====================================
1136 Here are some various ideas/recommendations that have been proposed
1137 while all this has been defined and implemented.
1139 - The bootloader may want to be able to use the device-tree itself
1140 and may want to manipulate it (to add/edit some properties,
1141 like physical memory size or kernel arguments). At this point, 2
1142 choices can be made. Either the bootloader works directly on the
1143 flattened format, or the bootloader has its own internal tree
1144 representation with pointers (similar to the kernel one) and
1145 re-flattens the tree when booting the kernel. The former is a bit
1146 more difficult to edit/modify, the later requires probably a bit
1147 more code to handle the tree structure. Note that the structure
1148 format has been designed so it's relatively easy to "insert"
1149 properties or nodes or delete them by just memmoving things
1150 around. It contains no internal offsets or pointers for this
1153 - An example of code for iterating nodes & retrieving properties
1154 directly from the flattened tree format can be found in the kernel
1155 file arch/ppc64/kernel/prom.c, look at scan_flat_dt() function,
1156 its usage in early_init_devtree(), and the corresponding various
1157 early_init_dt_scan_*() callbacks. That code can be re-used in a
1158 GPL bootloader, and as the author of that code, I would be happy
1159 to discuss possible free licensing to any vendor who wishes to
1160 integrate all or part of this code into a non-GPL bootloader.
1164 VI - System-on-a-chip devices and nodes
1165 =======================================
1167 Many companies are now starting to develop system-on-a-chip
1168 processors, where the processor core (CPU) and many peripheral devices
1169 exist on a single piece of silicon. For these SOCs, an SOC node
1170 should be used that defines child nodes for the devices that make
1171 up the SOC. While platforms are not required to use this model in
1172 order to boot the kernel, it is highly encouraged that all SOC
1173 implementations define as complete a flat-device-tree as possible to
1174 describe the devices on the SOC. This will allow for the
1175 genericization of much of the kernel code.
1178 1) Defining child nodes of an SOC
1179 ---------------------------------
1181 Each device that is part of an SOC may have its own node entry inside
1182 the SOC node. For each device that is included in the SOC, the unit
1183 address property represents the address offset for this device's
1184 memory-mapped registers in the parent's address space. The parent's
1185 address space is defined by the "ranges" property in the top-level soc
1186 node. The "reg" property for each node that exists directly under the
1187 SOC node should contain the address mapping from the child address space
1188 to the parent SOC address space and the size of the device's
1189 memory-mapped register file.
1191 For many devices that may exist inside an SOC, there are predefined
1192 specifications for the format of the device tree node. All SOC child
1193 nodes should follow these specifications, except where noted in this
1196 See appendix A for an example partial SOC node definition for the
1200 2) Representing devices without a current OF specification
1201 ----------------------------------------------------------
1203 Currently, there are many devices on SOCs that do not have a standard
1204 representation pre-defined as part of the open firmware
1205 specifications, mainly because the boards that contain these SOCs are
1206 not currently booted using open firmware. This section contains
1207 descriptions for the SOC devices for which new nodes have been
1208 defined; this list will expand as more and more SOC-containing
1209 platforms are moved over to use the flattened-device-tree model.
1213 The MDIO is a bus to which the PHY devices are connected. For each
1214 device that exists on this bus, a child node should be created. See
1215 the definition of the PHY node below for an example of how to define
1218 Required properties:
1219 - reg : Offset and length of the register set for the device
1220 - device_type : Should be "mdio"
1221 - compatible : Should define the compatible device type for the
1222 mdio. Currently, this is most likely to be "gianfar"
1228 device_type = "mdio";
1229 compatible = "gianfar";
1237 b) Gianfar-compatible ethernet nodes
1239 Required properties:
1241 - device_type : Should be "network"
1242 - model : Model of the device. Can be "TSEC", "eTSEC", or "FEC"
1243 - compatible : Should be "gianfar"
1244 - reg : Offset and length of the register set for the device
1245 - mac-address : List of bytes representing the ethernet address of
1247 - interrupts : <a b> where a is the interrupt number and b is a
1248 field that represents an encoding of the sense and level
1249 information for the interrupt. This should be encoded based on
1250 the information in section 2) depending on the type of interrupt
1251 controller you have.
1252 - interrupt-parent : the phandle for the interrupt controller that
1253 services interrupts for this device.
1254 - phy-handle : The phandle for the PHY connected to this ethernet
1257 Recommended properties:
1259 - linux,network-index : This is the intended "index" of this
1260 network device. This is used by the bootwrapper to interpret
1261 MAC addresses passed by the firmware when no information other
1262 than indices is available to associate an address with a device.
1263 - phy-connection-type : a string naming the controller/PHY interface type,
1264 i.e., "mii" (default), "rmii", "gmii", "rgmii", "rgmii-id", "sgmii",
1265 "tbi", or "rtbi". This property is only really needed if the connection
1266 is of type "rgmii-id", as all other connection types are detected by
1274 device_type = "network";
1276 compatible = "gianfar";
1278 mac-address = [ 00 E0 0C 00 73 00 ];
1279 interrupts = <d 3 e 3 12 3>;
1280 interrupt-parent = <40000>;
1281 phy-handle = <2452000>
1288 Required properties:
1290 - device_type : Should be "ethernet-phy"
1291 - interrupts : <a b> where a is the interrupt number and b is a
1292 field that represents an encoding of the sense and level
1293 information for the interrupt. This should be encoded based on
1294 the information in section 2) depending on the type of interrupt
1295 controller you have.
1296 - interrupt-parent : the phandle for the interrupt controller that
1297 services interrupts for this device.
1298 - reg : The ID number for the phy, usually a small integer
1299 - linux,phandle : phandle for this node; likely referenced by an
1300 ethernet controller node.
1306 linux,phandle = <2452000>
1307 interrupt-parent = <40000>;
1308 interrupts = <35 1>;
1310 device_type = "ethernet-phy";
1314 d) Interrupt controllers
1316 Some SOC devices contain interrupt controllers that are different
1317 from the standard Open PIC specification. The SOC device nodes for
1318 these types of controllers should be specified just like a standard
1319 OpenPIC controller. Sense and level information should be encoded
1320 as specified in section 2) of this chapter for each device that
1321 specifies an interrupt.
1326 linux,phandle = <40000>;
1327 clock-frequency = <0>;
1328 interrupt-controller;
1329 #address-cells = <0>;
1330 reg = <40000 40000>;
1332 compatible = "chrp,open-pic";
1333 device_type = "open-pic";
1340 Required properties :
1342 - device_type : Should be "i2c"
1343 - reg : Offset and length of the register set for the device
1345 Recommended properties :
1347 - compatible : Should be "fsl-i2c" for parts compatible with
1348 Freescale I2C specifications.
1349 - interrupts : <a b> where a is the interrupt number and b is a
1350 field that represents an encoding of the sense and level
1351 information for the interrupt. This should be encoded based on
1352 the information in section 2) depending on the type of interrupt
1353 controller you have.
1354 - interrupt-parent : the phandle for the interrupt controller that
1355 services interrupts for this device.
1356 - dfsrr : boolean; if defined, indicates that this I2C device has
1357 a digital filter sampling rate register
1358 - fsl5200-clocking : boolean; if defined, indicated that this device
1359 uses the FSL 5200 clocking mechanism.
1364 interrupt-parent = <40000>;
1365 interrupts = <1b 3>;
1367 device_type = "i2c";
1368 compatible = "fsl-i2c";
1373 f) Freescale SOC USB controllers
1375 The device node for a USB controller that is part of a Freescale
1376 SOC is as described in the document "Open Firmware Recommended
1377 Practice : Universal Serial Bus" with the following modifications
1380 Required properties :
1381 - compatible : Should be "fsl-usb2-mph" for multi port host USB
1382 controllers, or "fsl-usb2-dr" for dual role USB controllers
1383 - phy_type : For multi port host USB controllers, should be one of
1384 "ulpi", or "serial". For dual role USB controllers, should be
1385 one of "ulpi", "utmi", "utmi_wide", or "serial".
1386 - reg : Offset and length of the register set for the device
1387 - port0 : boolean; if defined, indicates port0 is connected for
1388 fsl-usb2-mph compatible controllers. Either this property or
1389 "port1" (or both) must be defined for "fsl-usb2-mph" compatible
1391 - port1 : boolean; if defined, indicates port1 is connected for
1392 fsl-usb2-mph compatible controllers. Either this property or
1393 "port0" (or both) must be defined for "fsl-usb2-mph" compatible
1395 - dr_mode : indicates the working mode for "fsl-usb2-dr" compatible
1396 controllers. Can be "host", "peripheral", or "otg". Default to
1397 "host" if not defined for backward compatibility.
1399 Recommended properties :
1400 - interrupts : <a b> where a is the interrupt number and b is a
1401 field that represents an encoding of the sense and level
1402 information for the interrupt. This should be encoded based on
1403 the information in section 2) depending on the type of interrupt
1404 controller you have.
1405 - interrupt-parent : the phandle for the interrupt controller that
1406 services interrupts for this device.
1408 Example multi port host USB controller device node :
1410 device_type = "usb";
1411 compatible = "fsl-usb2-mph";
1413 #address-cells = <1>;
1415 interrupt-parent = <700>;
1416 interrupts = <27 1>;
1422 Example dual role USB controller device node :
1424 device_type = "usb";
1425 compatible = "fsl-usb2-dr";
1427 #address-cells = <1>;
1429 interrupt-parent = <700>;
1430 interrupts = <26 1>;
1436 g) Freescale SOC SEC Security Engines
1438 Required properties:
1440 - device_type : Should be "crypto"
1441 - model : Model of the device. Should be "SEC1" or "SEC2"
1442 - compatible : Should be "talitos"
1443 - reg : Offset and length of the register set for the device
1444 - interrupts : <a b> where a is the interrupt number and b is a
1445 field that represents an encoding of the sense and level
1446 information for the interrupt. This should be encoded based on
1447 the information in section 2) depending on the type of interrupt
1448 controller you have.
1449 - interrupt-parent : the phandle for the interrupt controller that
1450 services interrupts for this device.
1451 - num-channels : An integer representing the number of channels
1453 - channel-fifo-len : An integer representing the number of
1454 descriptor pointers each channel fetch fifo can hold.
1455 - exec-units-mask : The bitmask representing what execution units
1456 (EUs) are available. It's a single 32-bit cell. EU information
1457 should be encoded following the SEC's Descriptor Header Dword
1458 EU_SEL0 field documentation, i.e. as follows:
1460 bit 0 = reserved - should be 0
1461 bit 1 = set if SEC has the ARC4 EU (AFEU)
1462 bit 2 = set if SEC has the DES/3DES EU (DEU)
1463 bit 3 = set if SEC has the message digest EU (MDEU)
1464 bit 4 = set if SEC has the random number generator EU (RNG)
1465 bit 5 = set if SEC has the public key EU (PKEU)
1466 bit 6 = set if SEC has the AES EU (AESU)
1467 bit 7 = set if SEC has the Kasumi EU (KEU)
1469 bits 8 through 31 are reserved for future SEC EUs.
1471 - descriptor-types-mask : The bitmask representing what descriptors
1472 are available. It's a single 32-bit cell. Descriptor type
1473 information should be encoded following the SEC's Descriptor
1474 Header Dword DESC_TYPE field documentation, i.e. as follows:
1476 bit 0 = set if SEC supports the aesu_ctr_nonsnoop desc. type
1477 bit 1 = set if SEC supports the ipsec_esp descriptor type
1478 bit 2 = set if SEC supports the common_nonsnoop desc. type
1479 bit 3 = set if SEC supports the 802.11i AES ccmp desc. type
1480 bit 4 = set if SEC supports the hmac_snoop_no_afeu desc. type
1481 bit 5 = set if SEC supports the srtp descriptor type
1482 bit 6 = set if SEC supports the non_hmac_snoop_no_afeu desc.type
1483 bit 7 = set if SEC supports the pkeu_assemble descriptor type
1484 bit 8 = set if SEC supports the aesu_key_expand_output desc.type
1485 bit 9 = set if SEC supports the pkeu_ptmul descriptor type
1486 bit 10 = set if SEC supports the common_nonsnoop_afeu desc. type
1487 bit 11 = set if SEC supports the pkeu_ptadd_dbl descriptor type
1489 ..and so on and so forth.
1495 device_type = "crypto";
1497 compatible = "talitos";
1498 reg = <30000 10000>;
1499 interrupts = <1d 3>;
1500 interrupt-parent = <40000>;
1502 channel-fifo-len = <18>;
1503 exec-units-mask = <000000fe>;
1504 descriptor-types-mask = <012b0ebf>;
1507 h) Board Control and Status (BCSR)
1509 Required properties:
1511 - device_type : Should be "board-control"
1512 - reg : Offset and length of the register set for the device
1517 device_type = "board-control";
1518 reg = <f8000000 8000>;
1521 i) Freescale QUICC Engine module (QE)
1522 This represents qe module that is installed on PowerQUICC II Pro.
1524 NOTE: This is an interim binding; it should be updated to fit
1525 in with the CPM binding later in this document.
1527 Basically, it is a bus of devices, that could act more or less
1528 as a complete entity (UCC, USB etc ). All of them should be siblings on
1529 the "root" qe node, using the common properties from there.
1530 The description below applies to the qe of MPC8360 and
1531 more nodes and properties would be extended in the future.
1535 Required properties:
1536 - device_type : should be "qe";
1537 - model : precise model of the QE, Can be "QE", "CPM", or "CPM2"
1538 - reg : offset and length of the device registers.
1539 - bus-frequency : the clock frequency for QUICC Engine.
1541 Recommended properties
1542 - brg-frequency : the internal clock source frequency for baud-rate
1547 #address-cells = <1>;
1549 #interrupt-cells = <2>;
1552 ranges = <0 e0100000 00100000>;
1553 reg = <e0100000 480>;
1554 brg-frequency = <0>;
1555 bus-frequency = <179A7B00>;
1559 ii) SPI (Serial Peripheral Interface)
1561 Required properties:
1562 - device_type : should be "spi".
1563 - compatible : should be "fsl_spi".
1564 - mode : the SPI operation mode, it can be "cpu" or "cpu-qe".
1565 - reg : Offset and length of the register set for the device
1566 - interrupts : <a b> where a is the interrupt number and b is a
1567 field that represents an encoding of the sense and level
1568 information for the interrupt. This should be encoded based on
1569 the information in section 2) depending on the type of interrupt
1570 controller you have.
1571 - interrupt-parent : the phandle for the interrupt controller that
1572 services interrupts for this device.
1576 device_type = "spi";
1577 compatible = "fsl_spi";
1579 interrupts = <82 0>;
1580 interrupt-parent = <700>;
1585 iii) USB (Universal Serial Bus Controller)
1587 Required properties:
1588 - device_type : should be "usb".
1589 - compatible : could be "qe_udc" or "fhci-hcd".
1590 - mode : the could be "host" or "slave".
1591 - reg : Offset and length of the register set for the device
1592 - interrupts : <a b> where a is the interrupt number and b is a
1593 field that represents an encoding of the sense and level
1594 information for the interrupt. This should be encoded based on
1595 the information in section 2) depending on the type of interrupt
1596 controller you have.
1597 - interrupt-parent : the phandle for the interrupt controller that
1598 services interrupts for this device.
1602 device_type = "usb";
1603 compatible = "qe_udc";
1605 interrupts = <8b 0>;
1606 interrupt-parent = <700>;
1611 iv) UCC (Unified Communications Controllers)
1613 Required properties:
1614 - device_type : should be "network", "hldc", "uart", "transparent"
1616 - compatible : could be "ucc_geth" or "fsl_atm" and so on.
1617 - model : should be "UCC".
1618 - device-id : the ucc number(1-8), corresponding to UCCx in UM.
1619 - reg : Offset and length of the register set for the device
1620 - interrupts : <a b> where a is the interrupt number and b is a
1621 field that represents an encoding of the sense and level
1622 information for the interrupt. This should be encoded based on
1623 the information in section 2) depending on the type of interrupt
1624 controller you have.
1625 - interrupt-parent : the phandle for the interrupt controller that
1626 services interrupts for this device.
1627 - pio-handle : The phandle for the Parallel I/O port configuration.
1628 - rx-clock : represents the UCC receive clock source.
1629 0x00 : clock source is disabled;
1630 0x1~0x10 : clock source is BRG1~BRG16 respectively;
1631 0x11~0x28: clock source is QE_CLK1~QE_CLK24 respectively.
1632 - tx-clock: represents the UCC transmit clock source;
1633 0x00 : clock source is disabled;
1634 0x1~0x10 : clock source is BRG1~BRG16 respectively;
1635 0x11~0x28: clock source is QE_CLK1~QE_CLK24 respectively.
1637 Required properties for network device_type:
1638 - mac-address : list of bytes representing the ethernet address.
1639 - phy-handle : The phandle for the PHY connected to this controller.
1641 Recommended properties:
1642 - linux,network-index : This is the intended "index" of this
1643 network device. This is used by the bootwrapper to interpret
1644 MAC addresses passed by the firmware when no information other
1645 than indices is available to associate an address with a device.
1646 - phy-connection-type : a string naming the controller/PHY interface type,
1647 i.e., "mii" (default), "rmii", "gmii", "rgmii", "rgmii-id", "tbi",
1652 device_type = "network";
1653 compatible = "ucc_geth";
1657 interrupts = <a0 0>;
1658 interrupt-parent = <700>;
1659 mac-address = [ 00 04 9f 00 23 23 ];
1662 phy-handle = <212000>;
1663 phy-connection-type = "gmii";
1664 pio-handle = <140001>;
1668 v) Parallel I/O Ports
1670 This node configures Parallel I/O ports for CPUs with QE support.
1671 The node should reside in the "soc" node of the tree. For each
1672 device that using parallel I/O ports, a child node should be created.
1673 See the definition of the Pin configuration nodes below for more
1676 Required properties:
1677 - device_type : should be "par_io".
1678 - reg : offset to the register set and its length.
1679 - num-ports : number of Parallel I/O ports
1684 #address-cells = <1>;
1686 device_type = "par_io";
1693 vi) Pin configuration nodes
1695 Required properties:
1696 - linux,phandle : phandle of this node; likely referenced by a QE
1698 - pio-map : array of pin configurations. Each pin is defined by 6
1699 integers. The six numbers are respectively: port, pin, dir,
1700 open_drain, assignment, has_irq.
1701 - port : port number of the pin; 0-6 represent port A-G in UM.
1702 - pin : pin number in the port.
1703 - dir : direction of the pin, should encode as follows:
1705 0 = The pin is disabled
1706 1 = The pin is an output
1707 2 = The pin is an input
1710 - open_drain : indicates the pin is normal or wired-OR:
1712 0 = The pin is actively driven as an output
1713 1 = The pin is an open-drain driver. As an output, the pin is
1714 driven active-low, otherwise it is three-stated.
1716 - assignment : function number of the pin according to the Pin Assignment
1717 tables in User Manual. Each pin can have up to 4 possible functions in
1718 QE and two options for CPM.
1719 - has_irq : indicates if the pin is used as source of external
1724 linux,phandle = <140001>;
1726 /* port pin dir open_drain assignment has_irq */
1727 0 3 1 0 1 0 /* TxD0 */
1728 0 4 1 0 1 0 /* TxD1 */
1729 0 5 1 0 1 0 /* TxD2 */
1730 0 6 1 0 1 0 /* TxD3 */
1731 1 6 1 0 3 0 /* TxD4 */
1732 1 7 1 0 1 0 /* TxD5 */
1733 1 9 1 0 2 0 /* TxD6 */
1734 1 a 1 0 2 0 /* TxD7 */
1735 0 9 2 0 1 0 /* RxD0 */
1736 0 a 2 0 1 0 /* RxD1 */
1737 0 b 2 0 1 0 /* RxD2 */
1738 0 c 2 0 1 0 /* RxD3 */
1739 0 d 2 0 1 0 /* RxD4 */
1740 1 1 2 0 2 0 /* RxD5 */
1741 1 0 2 0 2 0 /* RxD6 */
1742 1 4 2 0 2 0 /* RxD7 */
1743 0 7 1 0 1 0 /* TX_EN */
1744 0 8 1 0 1 0 /* TX_ER */
1745 0 f 2 0 1 0 /* RX_DV */
1746 0 10 2 0 1 0 /* RX_ER */
1747 0 0 2 0 1 0 /* RX_CLK */
1748 2 9 1 0 3 0 /* GTX_CLK - CLK10 */
1749 2 8 2 0 1 0>; /* GTX125 - CLK9 */
1752 vii) Multi-User RAM (MURAM)
1754 Required properties:
1755 - device_type : should be "muram".
1756 - mode : the could be "host" or "slave".
1757 - ranges : Should be defined as specified in 1) to describe the
1758 translation of MURAM addresses.
1759 - data-only : sub-node which defines the address area under MURAM
1760 bus that can be allocated as data/parameter
1765 device_type = "muram";
1766 ranges = <0 00010000 0000c000>;
1773 j) CFI or JEDEC memory-mapped NOR flash
1775 Flash chips (Memory Technology Devices) are often used for solid state
1776 file systems on embedded devices.
1778 - compatible : should contain the specific model of flash chip(s)
1779 used, if known, followed by either "cfi-flash" or "jedec-flash"
1780 - reg : Address range of the flash chip
1781 - bank-width : Width (in bytes) of the flash bank. Equal to the
1782 device width times the number of interleaved chips.
1783 - device-width : (optional) Width of a single flash chip. If
1784 omitted, assumed to be equal to 'bank-width'.
1785 - #address-cells, #size-cells : Must be present if the flash has
1786 sub-nodes representing partitions (see below). In this case
1787 both #address-cells and #size-cells must be equal to 1.
1789 For JEDEC compatible devices, the following additional properties
1792 - vendor-id : Contains the flash chip's vendor id (1 byte).
1793 - device-id : Contains the flash chip's device id (1 byte).
1795 In addition to the information on the flash bank itself, the
1796 device tree may optionally contain additional information
1797 describing partitions of the flash address space. This can be
1798 used on platforms which have strong conventions about which
1799 portions of the flash are used for what purposes, but which don't
1800 use an on-flash partition table such as RedBoot.
1802 Each partition is represented as a sub-node of the flash device.
1803 Each node's name represents the name of the corresponding
1804 partition of the flash device.
1807 - reg : The partition's offset and size within the flash bank.
1808 - label : (optional) The label / name for this flash partition.
1809 If omitted, the label is taken from the node name (excluding
1811 - read-only : (optional) This parameter, if present, is a hint to
1812 Linux that this flash partition should only be mounted
1813 read-only. This is usually used for flash partitions
1814 containing early-boot firmware images or data which should not
1820 compatible = "amd,am29lv128ml", "cfi-flash";
1821 reg = <ff000000 01000000>;
1824 #address-cells = <1>;
1832 reg = <f80000 80000>;
1837 k) Global Utilities Block
1839 The global utilities block controls power management, I/O device
1840 enabling, power-on-reset configuration monitoring, general-purpose
1841 I/O signal configuration, alternate function selection for multiplexed
1842 signals, and clock control.
1844 Required properties:
1846 - compatible : Should define the compatible device type for
1848 - reg : Offset and length of the register set for the device.
1850 Recommended properties:
1852 - fsl,has-rstcr : Indicates that the global utilities register set
1853 contains a functioning "reset control register" (i.e. the board
1854 is wired to reset upon setting the HRESET_REQ bit in this register).
1858 global-utilities@e0000 { /* global utilities block */
1859 compatible = "fsl,mpc8548-guts";
1864 l) Freescale Communications Processor Module
1866 NOTE: This is an interim binding, and will likely change slightly,
1867 as more devices are supported. The QE bindings especially are
1873 - compatible : "fsl,cpm1", "fsl,cpm2", or "fsl,qe".
1874 - reg : A 48-byte region beginning with CPCR.
1878 #address-cells = <1>;
1880 #interrupt-cells = <2>;
1881 compatible = "fsl,mpc8272-cpm", "fsl,cpm2";
1885 ii) Properties common to mulitple CPM/QE devices
1887 - fsl,cpm-command : This value is ORed with the opcode and command flag
1888 to specify the device on which a CPM command operates.
1890 - fsl,cpm-brg : Indicates which baud rate generator the device
1891 is associated with. If absent, an unused BRG
1892 should be dynamically allocated. If zero, the
1893 device uses an external clock rather than a BRG.
1895 - reg : Unless otherwise specified, the first resource represents the
1896 scc/fcc/ucc registers, and the second represents the device's
1897 parameter RAM region (if it has one).
1901 Currently defined compatibles:
1911 device_type = "serial";
1912 compatible = "fsl,mpc8272-scc-uart",
1913 "fsl,cpm2-scc-uart";
1914 reg = <11a00 20 8000 100>;
1915 interrupts = <28 8>;
1916 interrupt-parent = <&PIC>;
1918 fsl,cpm-command = <00800000>;
1923 Currently defined compatibles:
1927 - fsl,cpm2-fcc-enet (third resource is GFEMR)
1933 device_type = "network";
1934 compatible = "fsl,mpc8272-fcc-enet",
1935 "fsl,cpm2-fcc-enet";
1936 reg = <11300 20 8400 100 11390 1>;
1937 local-mac-address = [ 00 00 00 00 00 00 ];
1938 interrupts = <20 8>;
1939 interrupt-parent = <&PIC>;
1940 phy-handle = <&PHY0>;
1941 linux,network-index = <0>;
1942 fsl,cpm-command = <12000300>;
1947 Currently defined compatibles:
1948 fsl,pq1-fec-mdio (reg is same as first resource of FEC device)
1949 fsl,cpm2-mdio-bitbang (reg is port C registers)
1951 Properties for fsl,cpm2-mdio-bitbang:
1952 fsl,mdio-pin : pin of port C controlling mdio data
1953 fsl,mdc-pin : pin of port C controlling mdio clock
1958 device_type = "mdio";
1959 compatible = "fsl,mpc8272ads-mdio-bitbang",
1960 "fsl,mpc8272-mdio-bitbang",
1961 "fsl,cpm2-mdio-bitbang";
1963 #address-cells = <1>;
1965 fsl,mdio-pin = <12>;
1969 v) Baud Rate Generators
1971 Currently defined compatibles:
1977 - reg : There may be an arbitrary number of reg resources; BRG
1978 numbers are assigned to these in order.
1979 - clock-frequency : Specifies the base frequency driving
1985 compatible = "fsl,mpc8272-brg",
1988 reg = <119f0 10 115f0 10>;
1989 clock-frequency = <d#25000000>;
1992 vi) Interrupt Controllers
1994 Currently defined compatibles:
1996 - only one interrupt cell
1999 - second interrupt cell is level/sense:
2005 interrupt-controller@10c00 {
2006 #interrupt-cells = <2>;
2007 interrupt-controller;
2009 compatible = "mpc8272-pic", "fsl,cpm2-pic";
2012 vii) USB (Universal Serial Bus Controller)
2015 - compatible : "fsl,cpm1-usb", "fsl,cpm2-usb", "fsl,qe-usb"
2019 #address-cells = <1>;
2021 compatible = "fsl,cpm2-usb";
2022 reg = <11b60 18 8b00 100>;
2024 interrupt-parent = <&PIC>;
2025 fsl,cpm-command = <2e600000>;
2028 viii) Multi-User RAM (MURAM)
2030 The multi-user/dual-ported RAM is expressed as a bus under the CPM node.
2032 Ranges must be set up subject to the following restrictions:
2034 - Children's reg nodes must be offsets from the start of all muram, even
2035 if the user-data area does not begin at zero.
2036 - If multiple range entries are used, the difference between the parent
2037 address and the child address must be the same in all, so that a single
2038 mapping can cover them all while maintaining the ability to determine
2039 CPM-side offsets with pointer subtraction. It is recommended that
2040 multiple range entries not be used.
2041 - A child address of zero must be translatable, even if no reg resources
2044 A child "data" node must exist, compatible with "fsl,cpm-muram-data", to
2045 indicate the portion of muram that is usable by the OS for arbitrary
2046 purposes. The data node may have an arbitrary number of reg resources,
2047 all of which contribute to the allocatable muram pool.
2049 Example, based on mpc8272:
2052 #address-cells = <1>;
2054 ranges = <0 0 10000>;
2057 compatible = "fsl,cpm-muram-data";
2058 reg = <0 2000 9800 800>;
2062 m) Chipselect/Local Bus
2065 - name : Should be localbus
2066 - #address-cells : Should be either two or three. The first cell is the
2067 chipselect number, and the remaining cells are the
2068 offset into the chipselect.
2069 - #size-cells : Either one or two, depending on how large each chipselect
2071 - ranges : Each range corresponds to a single chipselect, and cover
2072 the entire access window as configured.
2076 compatible = "fsl,mpc8272ads-localbus",
2077 "fsl,mpc8272-localbus",
2079 #address-cells = <2>;
2081 reg = <f0010100 40>;
2083 ranges = <0 0 fe000000 02000000
2084 1 0 f4500000 00008000>;
2087 compatible = "jedec-flash";
2088 reg = <0 0 2000000>;
2095 compatible = "fsl,mpc8272ads-bcsr";
2100 n) 4xx/Axon EMAC ethernet nodes
2102 The EMAC ethernet controller in IBM and AMCC 4xx chips, and also
2103 the Axon bridge. To operate this needs to interact with a ths
2104 special McMAL DMA controller, and sometimes an RGMII or ZMII
2105 interface. In addition to the nodes and properties described
2106 below, the node for the OPB bus on which the EMAC sits must have a
2107 correct clock-frequency property.
2109 i) The EMAC node itself
2111 Required properties:
2112 - device_type : "network"
2114 - compatible : compatible list, contains 2 entries, first is
2115 "ibm,emac-CHIP" where CHIP is the host ASIC (440gx,
2116 405gp, Axon) and second is either "ibm,emac" or
2117 "ibm,emac4". For Axon, thus, we have: "ibm,emac-axon",
2119 - interrupts : <interrupt mapping for EMAC IRQ and WOL IRQ>
2120 - interrupt-parent : optional, if needed for interrupt mapping
2121 - reg : <registers mapping>
2122 - local-mac-address : 6 bytes, MAC address
2123 - mal-device : phandle of the associated McMAL node
2124 - mal-tx-channel : 1 cell, index of the tx channel on McMAL associated
2126 - mal-rx-channel : 1 cell, index of the rx channel on McMAL associated
2128 - cell-index : 1 cell, hardware index of the EMAC cell on a given
2129 ASIC (typically 0x0 and 0x1 for EMAC0 and EMAC1 on
2131 - max-frame-size : 1 cell, maximum frame size supported in bytes
2132 - rx-fifo-size : 1 cell, Rx fifo size in bytes for 10 and 100 Mb/sec
2135 - tx-fifo-size : 1 cell, Tx fifo size in bytes for 10 and 100 Mb/sec
2138 - fifo-entry-size : 1 cell, size of a fifo entry (used to calculate
2140 For Axon, 0x00000010
2141 - mal-burst-size : 1 cell, MAL burst size (used to calculate thresholds)
2143 For Axon, 0x00000100 (I think ...)
2144 - phy-mode : string, mode of operations of the PHY interface.
2145 Supported values are: "mii", "rmii", "smii", "rgmii",
2146 "tbi", "gmii", rtbi", "sgmii".
2147 For Axon on CAB, it is "rgmii"
2148 - mdio-device : 1 cell, required iff using shared MDIO registers
2149 (440EP). phandle of the EMAC to use to drive the
2150 MDIO lines for the PHY used by this EMAC.
2151 - zmii-device : 1 cell, required iff connected to a ZMII. phandle of
2152 the ZMII device node
2153 - zmii-channel : 1 cell, required iff connected to a ZMII. Which ZMII
2154 channel or 0xffffffff if ZMII is only used for MDIO.
2155 - rgmii-device : 1 cell, required iff connected to an RGMII. phandle
2156 of the RGMII device node.
2157 For Axon: phandle of plb5/plb4/opb/rgmii
2158 - rgmii-channel : 1 cell, required iff connected to an RGMII. Which
2159 RGMII channel is used by this EMAC.
2160 Fox Axon: present, whatever value is appropriate for each
2161 EMAC, that is the content of the current (bogus) "phy-port"
2164 Recommended properties:
2165 - linux,network-index : This is the intended "index" of this
2166 network device. This is used by the bootwrapper to interpret
2167 MAC addresses passed by the firmware when no information other
2168 than indices is available to associate an address with a device.
2170 Optional properties:
2171 - phy-address : 1 cell, optional, MDIO address of the PHY. If absent,
2172 a search is performed.
2173 - phy-map : 1 cell, optional, bitmap of addresses to probe the PHY
2174 for, used if phy-address is absent. bit 0x00000001 is
2176 For Axon it can be absent, thouugh my current driver
2177 doesn't handle phy-address yet so for now, keep
2179 - rx-fifo-size-gige : 1 cell, Rx fifo size in bytes for 1000 Mb/sec
2180 operations (if absent the value is the same as
2181 rx-fifo-size). For Axon, either absent or 2048.
2182 - tx-fifo-size-gige : 1 cell, Tx fifo size in bytes for 1000 Mb/sec
2183 operations (if absent the value is the same as
2184 tx-fifo-size). For Axon, either absent or 2048.
2185 - tah-device : 1 cell, optional. If connected to a TAH engine for
2186 offload, phandle of the TAH device node.
2187 - tah-channel : 1 cell, optional. If appropriate, channel used on the
2192 EMAC0: ethernet@40000800 {
2193 linux,network-index = <0>;
2194 device_type = "network";
2195 compatible = "ibm,emac-440gp", "ibm,emac";
2196 interrupt-parent = <&UIC1>;
2197 interrupts = <1c 4 1d 4>;
2198 reg = <40000800 70>;
2199 local-mac-address = [00 04 AC E3 1B 1E];
2200 mal-device = <&MAL0>;
2201 mal-tx-channel = <0 1>;
2202 mal-rx-channel = <0>;
2204 max-frame-size = <5dc>;
2205 rx-fifo-size = <1000>;
2206 tx-fifo-size = <800>;
2208 phy-map = <00000001>;
2209 zmii-device = <&ZMII0>;
2215 Required properties:
2216 - device_type : "dma-controller"
2217 - compatible : compatible list, containing 2 entries, first is
2218 "ibm,mcmal-CHIP" where CHIP is the host ASIC (like
2219 emac) and the second is either "ibm,mcmal" or
2221 For Axon, "ibm,mcmal-axon","ibm,mcmal2"
2222 - interrupts : <interrupt mapping for the MAL interrupts sources:
2223 5 sources: tx_eob, rx_eob, serr, txde, rxde>.
2224 For Axon: This is _different_ from the current
2225 firmware. We use the "delayed" interrupts for txeob
2226 and rxeob. Thus we end up with mapping those 5 MPIC
2227 interrupts, all level positive sensitive: 10, 11, 32,
2229 - dcr-reg : < DCR registers range >
2230 - dcr-parent : if needed for dcr-reg
2231 - num-tx-chans : 1 cell, number of Tx channels
2232 - num-rx-chans : 1 cell, number of Rx channels
2236 Required properties:
2237 - compatible : compatible list, containing 2 entries, first is
2238 "ibm,zmii-CHIP" where CHIP is the host ASIC (like
2239 EMAC) and the second is "ibm,zmii".
2240 For Axon, there is no ZMII node.
2241 - reg : <registers mapping>
2245 Required properties:
2246 - compatible : compatible list, containing 2 entries, first is
2247 "ibm,rgmii-CHIP" where CHIP is the host ASIC (like
2248 EMAC) and the second is "ibm,rgmii".
2249 For Axon, "ibm,rgmii-axon","ibm,rgmii"
2250 - reg : <registers mapping>
2251 - revision : as provided by the RGMII new version register if
2253 For Axon: 0x0000012a
2255 More devices will be defined as this spec matures.
2257 VII - Specifying interrupt information for devices
2258 ===================================================
2260 The device tree represents the busses and devices of a hardware
2261 system in a form similar to the physical bus topology of the
2264 In addition, a logical 'interrupt tree' exists which represents the
2265 hierarchy and routing of interrupts in the hardware.
2267 The interrupt tree model is fully described in the
2268 document "Open Firmware Recommended Practice: Interrupt
2269 Mapping Version 0.9". The document is available at:
2270 <http://playground.sun.com/1275/practice>.
2272 1) interrupts property
2273 ----------------------
2275 Devices that generate interrupts to a single interrupt controller
2276 should use the conventional OF representation described in the
2277 OF interrupt mapping documentation.
2279 Each device which generates interrupts must have an 'interrupt'
2280 property. The interrupt property value is an arbitrary number of
2281 of 'interrupt specifier' values which describe the interrupt or
2282 interrupts for the device.
2284 The encoding of an interrupt specifier is determined by the
2285 interrupt domain in which the device is located in the
2286 interrupt tree. The root of an interrupt domain specifies in
2287 its #interrupt-cells property the number of 32-bit cells
2288 required to encode an interrupt specifier. See the OF interrupt
2289 mapping documentation for a detailed description of domains.
2291 For example, the binding for the OpenPIC interrupt controller
2292 specifies an #interrupt-cells value of 2 to encode the interrupt
2293 number and level/sense information. All interrupt children in an
2294 OpenPIC interrupt domain use 2 cells per interrupt in their interrupts
2297 The PCI bus binding specifies a #interrupt-cell value of 1 to encode
2298 which interrupt pin (INTA,INTB,INTC,INTD) is used.
2300 2) interrupt-parent property
2301 ----------------------------
2303 The interrupt-parent property is specified to define an explicit
2304 link between a device node and its interrupt parent in
2305 the interrupt tree. The value of interrupt-parent is the
2306 phandle of the parent node.
2308 If the interrupt-parent property is not defined for a node, it's
2309 interrupt parent is assumed to be an ancestor in the node's
2310 _device tree_ hierarchy.
2312 3) OpenPIC Interrupt Controllers
2313 --------------------------------
2315 OpenPIC interrupt controllers require 2 cells to encode
2316 interrupt information. The first cell defines the interrupt
2317 number. The second cell defines the sense and level
2320 Sense and level information should be encoded as follows:
2322 0 = low to high edge sensitive type enabled
2323 1 = active low level sensitive type enabled
2324 2 = active high level sensitive type enabled
2325 3 = high to low edge sensitive type enabled
2327 4) ISA Interrupt Controllers
2328 ----------------------------
2330 ISA PIC interrupt controllers require 2 cells to encode
2331 interrupt information. The first cell defines the interrupt
2332 number. The second cell defines the sense and level
2335 ISA PIC interrupt controllers should adhere to the ISA PIC
2336 encodings listed below:
2338 0 = active low level sensitive type enabled
2339 1 = active high level sensitive type enabled
2340 2 = high to low edge sensitive type enabled
2341 3 = low to high edge sensitive type enabled
2344 Appendix A - Sample SOC node for MPC8540
2345 ========================================
2347 Note that the #address-cells and #size-cells for the SoC node
2348 in this example have been explicitly listed; these are likely
2349 not necessary as they are usually the same as the root node.
2352 #address-cells = <1>;
2354 #interrupt-cells = <2>;
2355 device_type = "soc";
2356 ranges = <00000000 e0000000 00100000>
2357 reg = <e0000000 00003000>;
2358 bus-frequency = <0>;
2362 device_type = "mdio";
2363 compatible = "gianfar";
2366 linux,phandle = <2452000>
2367 interrupt-parent = <40000>;
2368 interrupts = <35 1>;
2370 device_type = "ethernet-phy";
2374 linux,phandle = <2452001>
2375 interrupt-parent = <40000>;
2376 interrupts = <35 1>;
2378 device_type = "ethernet-phy";
2382 linux,phandle = <2452002>
2383 interrupt-parent = <40000>;
2384 interrupts = <35 1>;
2386 device_type = "ethernet-phy";
2393 device_type = "network";
2395 compatible = "gianfar";
2397 mac-address = [ 00 E0 0C 00 73 00 ];
2398 interrupts = <d 3 e 3 12 3>;
2399 interrupt-parent = <40000>;
2400 phy-handle = <2452000>;
2404 #address-cells = <1>;
2406 device_type = "network";
2408 compatible = "gianfar";
2410 mac-address = [ 00 E0 0C 00 73 01 ];
2411 interrupts = <13 3 14 3 18 3>;
2412 interrupt-parent = <40000>;
2413 phy-handle = <2452001>;
2417 #address-cells = <1>;
2419 device_type = "network";
2421 compatible = "gianfar";
2423 mac-address = [ 00 E0 0C 00 73 02 ];
2424 interrupts = <19 3>;
2425 interrupt-parent = <40000>;
2426 phy-handle = <2452002>;
2430 device_type = "serial";
2431 compatible = "ns16550";
2433 clock-frequency = <0>;
2434 interrupts = <1a 3>;
2435 interrupt-parent = <40000>;
2439 linux,phandle = <40000>;
2440 clock-frequency = <0>;
2441 interrupt-controller;
2442 #address-cells = <0>;
2443 reg = <40000 40000>;
2445 compatible = "chrp,open-pic";
2446 device_type = "open-pic";
2451 interrupt-parent = <40000>;
2452 interrupts = <1b 3>;
2454 device_type = "i2c";
2455 compatible = "fsl-i2c";
git.openpandora.org / pandora-kernel.git / blob