i2c: mux: Add register-based mux i2c-mux-reg

Based on i2c-mux-gpio driver, similarly the register-based mux
switch from one bus to another by setting a single register.
The register can be on PCIe bus, local bus, or any memory-mapped
address. The endianness of such register can be specified in device
tree if used, or in platform data.

Signed-off-by: York Sun <yorksun@freescale.com>
Acked-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
new file mode 100644 (file)
index 0000000..688783f
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
@@ -0,0 +1,74 @@
+Register-based I2C Bus Mux
+
+This binding describes an I2C bus multiplexer that uses a single register
+to route the I2C signals.
+
+Required properties:
+- compatible: i2c-mux-reg
+- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
+  port is connected to.
+* Standard I2C mux properties. See mux.txt in this directory.
+* I2C child bus nodes. See mux.txt in this directory.
+
+Optional properties:
+- reg: this pair of <offset size> specifies the register to control the mux.
+  The <offset size> depends on its parent node. It can be any memory-mapped
+  address. The size must be either 1, 2, or 4 bytes. If reg is omitted, the
+  resource of this device will be used.
+- little-endian: The existence indicates the register is in little endian.
+- big-endian: The existence indicates the register is in big endian.
+  If both little-endian and big-endian are omitted, the endianness of the
+  CPU will be used.
+- write-only: The existence indicates the register is write-only.
+- idle-state: value to set the muxer to when idle. When no value is
+  given, it defaults to the last value used.
+
+Whenever an access is made to a device on a child bus, the value set
+in the revelant node's reg property will be output to the register.
+
+If an idle state is defined, using the idle-state (optional) property,
+whenever an access is not being made to a device on a child bus, the
+register will be set according to the idle value.
+
+If an idle state is not defined, the most recently used value will be
+left programmed into the register.
+
+Example of a mux on PCIe card, the host is a powerpc SoC (big endian):
+
+       i2c-mux {
+               /* the <offset size> depends on the address translation
+                * of the parent device. If omitted, device resource
+                * will be used instead. The size is to determine
+                * whether iowrite32, iowrite16, or iowrite8 will be used.
+                */
+               reg = <0x6028 0x4>;
+               little-endian;          /* little endian register on PCIe */
+               compatible = "i2c-mux-reg";
+               #address-cells = <1>;
+               #size-cells = <0>;
+               i2c-parent = <&i2c1>;
+               i2c@0 {
+                       reg = <0>;
+                       #address-cells = <1>;
+                       #size-cells = <0>;
+
+                       si5338: clock-generator@70 {
+                               compatible = "silabs,si5338";
+                               reg = <0x70>;
+                               /* other stuff */
+                       };
+               };
+
+               i2c@1 {
+                       /* data is written using iowrite32 */
+                       reg = <1>;
+                       #address-cells = <1>;
+                       #size-cells = <0>;
+
+                       si5338: clock-generator@70 {
+                               compatible = "silabs,si5338";
+                               reg = <0x70>;
+                               /* other stuff */
+                       };
+               };
+       };

diff --cc drivers/i2c/muxes/Kconfig
Simple merge

diff --cc drivers/i2c/muxes/Makefile
Simple merge

diff --cc drivers/i2c/muxes/i2c-mux-reg.c
Simple merge

diff --cc include/linux/platform_data/i2c-mux-reg.h
Simple merge