1 /* i2c-core.c - a device driver for the iic-bus interface */
2 /* ------------------------------------------------------------------------- */
3 /* Copyright (C) 1995-99 Simon G. Vogl
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
18 /* ------------------------------------------------------------------------- */
20 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
21 All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
22 SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
23 Jean Delvare <khali@linux-fr.org>
24 Mux support by Rodolfo Giometti <giometti@enneenne.com> and
25 Michael Lawnick <michael.lawnick.ext@nsn.com> */
27 #include <linux/module.h>
28 #include <linux/kernel.h>
29 #include <linux/errno.h>
30 #include <linux/slab.h>
31 #include <linux/i2c.h>
32 #include <linux/init.h>
33 #include <linux/idr.h>
34 #include <linux/mutex.h>
35 #include <linux/of_device.h>
36 #include <linux/completion.h>
37 #include <linux/hardirq.h>
38 #include <linux/irqflags.h>
39 #include <linux/rwsem.h>
40 #include <linux/pm_runtime.h>
41 #include <asm/uaccess.h>
46 /* core_lock protects i2c_adapter_idr, and guarantees
47 that device detection, deletion of detected devices, and attach_adapter
48 and detach_adapter calls are serialized */
49 static DEFINE_MUTEX(core_lock);
50 static DEFINE_IDR(i2c_adapter_idr);
52 static struct device_type i2c_client_type;
53 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
55 /* ------------------------------------------------------------------------- */
57 static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
58 const struct i2c_client *client)
61 if (strcmp(client->name, id->name) == 0)
68 static int i2c_device_match(struct device *dev, struct device_driver *drv)
70 struct i2c_client *client = i2c_verify_client(dev);
71 struct i2c_driver *driver;
76 /* Attempt an OF style match */
77 if (of_driver_match_device(dev, drv))
80 driver = to_i2c_driver(drv);
81 /* match on an id table if there is one */
83 return i2c_match_id(driver->id_table, client) != NULL;
90 /* uevent helps with hotplug: modprobe -q $(MODALIAS) */
91 static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
93 struct i2c_client *client = to_i2c_client(dev);
95 if (add_uevent_var(env, "MODALIAS=%s%s",
96 I2C_MODULE_PREFIX, client->name))
98 dev_dbg(dev, "uevent\n");
103 #define i2c_device_uevent NULL
104 #endif /* CONFIG_HOTPLUG */
106 static int i2c_device_probe(struct device *dev)
108 struct i2c_client *client = i2c_verify_client(dev);
109 struct i2c_driver *driver;
115 driver = to_i2c_driver(dev->driver);
116 if (!driver->probe || !driver->id_table)
118 client->driver = driver;
119 if (!device_can_wakeup(&client->dev))
120 device_init_wakeup(&client->dev,
121 client->flags & I2C_CLIENT_WAKE);
122 dev_dbg(dev, "probe\n");
124 status = driver->probe(client, i2c_match_id(driver->id_table, client));
126 client->driver = NULL;
127 i2c_set_clientdata(client, NULL);
132 static int i2c_device_remove(struct device *dev)
134 struct i2c_client *client = i2c_verify_client(dev);
135 struct i2c_driver *driver;
138 if (!client || !dev->driver)
141 driver = to_i2c_driver(dev->driver);
142 if (driver->remove) {
143 dev_dbg(dev, "remove\n");
144 status = driver->remove(client);
150 client->driver = NULL;
151 i2c_set_clientdata(client, NULL);
156 static void i2c_device_shutdown(struct device *dev)
158 struct i2c_client *client = i2c_verify_client(dev);
159 struct i2c_driver *driver;
161 if (!client || !dev->driver)
163 driver = to_i2c_driver(dev->driver);
164 if (driver->shutdown)
165 driver->shutdown(client);
168 #ifdef CONFIG_PM_SLEEP
169 static int i2c_legacy_suspend(struct device *dev, pm_message_t mesg)
171 struct i2c_client *client = i2c_verify_client(dev);
172 struct i2c_driver *driver;
174 if (!client || !dev->driver)
176 driver = to_i2c_driver(dev->driver);
177 if (!driver->suspend)
179 return driver->suspend(client, mesg);
182 static int i2c_legacy_resume(struct device *dev)
184 struct i2c_client *client = i2c_verify_client(dev);
185 struct i2c_driver *driver;
187 if (!client || !dev->driver)
189 driver = to_i2c_driver(dev->driver);
192 return driver->resume(client);
195 static int i2c_device_pm_suspend(struct device *dev)
197 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
200 if (pm_runtime_suspended(dev))
203 return pm->suspend ? pm->suspend(dev) : 0;
206 return i2c_legacy_suspend(dev, PMSG_SUSPEND);
209 static int i2c_device_pm_resume(struct device *dev)
211 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
215 ret = pm->resume ? pm->resume(dev) : 0;
217 ret = i2c_legacy_resume(dev);
222 static int i2c_device_pm_freeze(struct device *dev)
224 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
227 if (pm_runtime_suspended(dev))
230 return pm->freeze ? pm->freeze(dev) : 0;
233 return i2c_legacy_suspend(dev, PMSG_FREEZE);
236 static int i2c_device_pm_thaw(struct device *dev)
238 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
241 if (pm_runtime_suspended(dev))
244 return pm->thaw ? pm->thaw(dev) : 0;
247 return i2c_legacy_resume(dev);
250 static int i2c_device_pm_poweroff(struct device *dev)
252 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
255 if (pm_runtime_suspended(dev))
258 return pm->poweroff ? pm->poweroff(dev) : 0;
261 return i2c_legacy_suspend(dev, PMSG_HIBERNATE);
264 static int i2c_device_pm_restore(struct device *dev)
266 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
270 ret = pm->restore ? pm->restore(dev) : 0;
272 ret = i2c_legacy_resume(dev);
275 pm_runtime_disable(dev);
276 pm_runtime_set_active(dev);
277 pm_runtime_enable(dev);
282 #else /* !CONFIG_PM_SLEEP */
283 #define i2c_device_pm_suspend NULL
284 #define i2c_device_pm_resume NULL
285 #define i2c_device_pm_freeze NULL
286 #define i2c_device_pm_thaw NULL
287 #define i2c_device_pm_poweroff NULL
288 #define i2c_device_pm_restore NULL
289 #endif /* !CONFIG_PM_SLEEP */
291 static void i2c_client_dev_release(struct device *dev)
293 kfree(to_i2c_client(dev));
297 show_name(struct device *dev, struct device_attribute *attr, char *buf)
299 return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
300 to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
304 show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
306 struct i2c_client *client = to_i2c_client(dev);
307 return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
310 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
311 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
313 static struct attribute *i2c_dev_attrs[] = {
315 /* modalias helps coldplug: modprobe $(cat .../modalias) */
316 &dev_attr_modalias.attr,
320 static struct attribute_group i2c_dev_attr_group = {
321 .attrs = i2c_dev_attrs,
324 static const struct attribute_group *i2c_dev_attr_groups[] = {
329 static const struct dev_pm_ops i2c_device_pm_ops = {
330 .suspend = i2c_device_pm_suspend,
331 .resume = i2c_device_pm_resume,
332 .freeze = i2c_device_pm_freeze,
333 .thaw = i2c_device_pm_thaw,
334 .poweroff = i2c_device_pm_poweroff,
335 .restore = i2c_device_pm_restore,
337 pm_generic_runtime_suspend,
338 pm_generic_runtime_resume,
339 pm_generic_runtime_idle
343 struct bus_type i2c_bus_type = {
345 .match = i2c_device_match,
346 .probe = i2c_device_probe,
347 .remove = i2c_device_remove,
348 .shutdown = i2c_device_shutdown,
349 .pm = &i2c_device_pm_ops,
351 EXPORT_SYMBOL_GPL(i2c_bus_type);
353 static struct device_type i2c_client_type = {
354 .groups = i2c_dev_attr_groups,
355 .uevent = i2c_device_uevent,
356 .release = i2c_client_dev_release,
361 * i2c_verify_client - return parameter as i2c_client, or NULL
362 * @dev: device, probably from some driver model iterator
364 * When traversing the driver model tree, perhaps using driver model
365 * iterators like @device_for_each_child(), you can't assume very much
366 * about the nodes you find. Use this function to avoid oopses caused
367 * by wrongly treating some non-I2C device as an i2c_client.
369 struct i2c_client *i2c_verify_client(struct device *dev)
371 return (dev->type == &i2c_client_type)
375 EXPORT_SYMBOL(i2c_verify_client);
378 /* This is a permissive address validity check, I2C address map constraints
379 * are purposedly not enforced, except for the general call address. */
380 static int i2c_check_client_addr_validity(const struct i2c_client *client)
382 if (client->flags & I2C_CLIENT_TEN) {
383 /* 10-bit address, all values are valid */
384 if (client->addr > 0x3ff)
387 /* 7-bit address, reject the general call address */
388 if (client->addr == 0x00 || client->addr > 0x7f)
394 /* And this is a strict address validity check, used when probing. If a
395 * device uses a reserved address, then it shouldn't be probed. 7-bit
396 * addressing is assumed, 10-bit address devices are rare and should be
397 * explicitly enumerated. */
398 static int i2c_check_addr_validity(unsigned short addr)
401 * Reserved addresses per I2C specification:
402 * 0x00 General call address / START byte
404 * 0x02 Reserved for different bus format
405 * 0x03 Reserved for future purposes
406 * 0x04-0x07 Hs-mode master code
407 * 0x78-0x7b 10-bit slave addressing
408 * 0x7c-0x7f Reserved for future purposes
410 if (addr < 0x08 || addr > 0x77)
415 static int __i2c_check_addr_busy(struct device *dev, void *addrp)
417 struct i2c_client *client = i2c_verify_client(dev);
418 int addr = *(int *)addrp;
420 if (client && client->addr == addr)
425 /* walk up mux tree */
426 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
428 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
431 result = device_for_each_child(&adapter->dev, &addr,
432 __i2c_check_addr_busy);
434 if (!result && parent)
435 result = i2c_check_mux_parents(parent, addr);
440 /* recurse down mux tree */
441 static int i2c_check_mux_children(struct device *dev, void *addrp)
445 if (dev->type == &i2c_adapter_type)
446 result = device_for_each_child(dev, addrp,
447 i2c_check_mux_children);
449 result = __i2c_check_addr_busy(dev, addrp);
454 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
456 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
460 result = i2c_check_mux_parents(parent, addr);
463 result = device_for_each_child(&adapter->dev, &addr,
464 i2c_check_mux_children);
470 * i2c_lock_adapter - Get exclusive access to an I2C bus segment
471 * @adapter: Target I2C bus segment
473 void i2c_lock_adapter(struct i2c_adapter *adapter)
475 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
478 i2c_lock_adapter(parent);
480 rt_mutex_lock(&adapter->bus_lock);
482 EXPORT_SYMBOL_GPL(i2c_lock_adapter);
485 * i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment
486 * @adapter: Target I2C bus segment
488 static int i2c_trylock_adapter(struct i2c_adapter *adapter)
490 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
493 return i2c_trylock_adapter(parent);
495 return rt_mutex_trylock(&adapter->bus_lock);
499 * i2c_unlock_adapter - Release exclusive access to an I2C bus segment
500 * @adapter: Target I2C bus segment
502 void i2c_unlock_adapter(struct i2c_adapter *adapter)
504 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
507 i2c_unlock_adapter(parent);
509 rt_mutex_unlock(&adapter->bus_lock);
511 EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
514 * i2c_new_device - instantiate an i2c device
515 * @adap: the adapter managing the device
516 * @info: describes one I2C device; bus_num is ignored
519 * Create an i2c device. Binding is handled through driver model
520 * probe()/remove() methods. A driver may be bound to this device when we
521 * return from this function, or any later moment (e.g. maybe hotplugging will
522 * load the driver module). This call is not appropriate for use by mainboard
523 * initialization logic, which usually runs during an arch_initcall() long
524 * before any i2c_adapter could exist.
526 * This returns the new i2c client, which may be saved for later use with
527 * i2c_unregister_device(); or NULL to indicate an error.
530 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
532 struct i2c_client *client;
535 client = kzalloc(sizeof *client, GFP_KERNEL);
539 client->adapter = adap;
541 client->dev.platform_data = info->platform_data;
544 client->dev.archdata = *info->archdata;
546 client->flags = info->flags;
547 client->addr = info->addr;
548 client->irq = info->irq;
550 strlcpy(client->name, info->type, sizeof(client->name));
552 /* Check for address validity */
553 status = i2c_check_client_addr_validity(client);
555 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
556 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
560 /* Check for address business */
561 status = i2c_check_addr_busy(adap, client->addr);
565 client->dev.parent = &client->adapter->dev;
566 client->dev.bus = &i2c_bus_type;
567 client->dev.type = &i2c_client_type;
569 client->dev.of_node = info->of_node;
572 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
574 status = device_register(&client->dev);
578 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
579 client->name, dev_name(&client->dev));
584 dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
585 "(%d)\n", client->name, client->addr, status);
590 EXPORT_SYMBOL_GPL(i2c_new_device);
594 * i2c_unregister_device - reverse effect of i2c_new_device()
595 * @client: value returned from i2c_new_device()
598 void i2c_unregister_device(struct i2c_client *client)
600 device_unregister(&client->dev);
602 EXPORT_SYMBOL_GPL(i2c_unregister_device);
605 static const struct i2c_device_id dummy_id[] = {
610 static int dummy_probe(struct i2c_client *client,
611 const struct i2c_device_id *id)
616 static int dummy_remove(struct i2c_client *client)
621 static struct i2c_driver dummy_driver = {
622 .driver.name = "dummy",
623 .probe = dummy_probe,
624 .remove = dummy_remove,
625 .id_table = dummy_id,
629 * i2c_new_dummy - return a new i2c device bound to a dummy driver
630 * @adapter: the adapter managing the device
631 * @address: seven bit address to be used
634 * This returns an I2C client bound to the "dummy" driver, intended for use
635 * with devices that consume multiple addresses. Examples of such chips
636 * include various EEPROMS (like 24c04 and 24c08 models).
638 * These dummy devices have two main uses. First, most I2C and SMBus calls
639 * except i2c_transfer() need a client handle; the dummy will be that handle.
640 * And second, this prevents the specified address from being bound to a
643 * This returns the new i2c client, which should be saved for later use with
644 * i2c_unregister_device(); or NULL to indicate an error.
646 struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
648 struct i2c_board_info info = {
649 I2C_BOARD_INFO("dummy", address),
652 return i2c_new_device(adapter, &info);
654 EXPORT_SYMBOL_GPL(i2c_new_dummy);
656 /* ------------------------------------------------------------------------- */
658 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
660 static void i2c_adapter_dev_release(struct device *dev)
662 struct i2c_adapter *adap = to_i2c_adapter(dev);
663 complete(&adap->dev_released);
667 * Let users instantiate I2C devices through sysfs. This can be used when
668 * platform initialization code doesn't contain the proper data for
669 * whatever reason. Also useful for drivers that do device detection and
670 * detection fails, either because the device uses an unexpected address,
671 * or this is a compatible device with different ID register values.
673 * Parameter checking may look overzealous, but we really don't want
674 * the user to provide incorrect parameters.
677 i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
678 const char *buf, size_t count)
680 struct i2c_adapter *adap = to_i2c_adapter(dev);
681 struct i2c_board_info info;
682 struct i2c_client *client;
686 dev_warn(dev, "The new_device interface is still experimental "
687 "and may change in a near future\n");
688 memset(&info, 0, sizeof(struct i2c_board_info));
690 blank = strchr(buf, ' ');
692 dev_err(dev, "%s: Missing parameters\n", "new_device");
695 if (blank - buf > I2C_NAME_SIZE - 1) {
696 dev_err(dev, "%s: Invalid device name\n", "new_device");
699 memcpy(info.type, buf, blank - buf);
701 /* Parse remaining parameters, reject extra parameters */
702 res = sscanf(++blank, "%hi%c", &info.addr, &end);
704 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
707 if (res > 1 && end != '\n') {
708 dev_err(dev, "%s: Extra parameters\n", "new_device");
712 client = i2c_new_device(adap, &info);
716 /* Keep track of the added device */
717 mutex_lock(&adap->userspace_clients_lock);
718 list_add_tail(&client->detected, &adap->userspace_clients);
719 mutex_unlock(&adap->userspace_clients_lock);
720 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
721 info.type, info.addr);
727 * And of course let the users delete the devices they instantiated, if
728 * they got it wrong. This interface can only be used to delete devices
729 * instantiated by i2c_sysfs_new_device above. This guarantees that we
730 * don't delete devices to which some kernel code still has references.
732 * Parameter checking may look overzealous, but we really don't want
733 * the user to delete the wrong device.
736 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
737 const char *buf, size_t count)
739 struct i2c_adapter *adap = to_i2c_adapter(dev);
740 struct i2c_client *client, *next;
745 /* Parse parameters, reject extra parameters */
746 res = sscanf(buf, "%hi%c", &addr, &end);
748 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
751 if (res > 1 && end != '\n') {
752 dev_err(dev, "%s: Extra parameters\n", "delete_device");
756 /* Make sure the device was added through sysfs */
758 mutex_lock(&adap->userspace_clients_lock);
759 list_for_each_entry_safe(client, next, &adap->userspace_clients,
761 if (client->addr == addr) {
762 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
763 "delete_device", client->name, client->addr);
765 list_del(&client->detected);
766 i2c_unregister_device(client);
771 mutex_unlock(&adap->userspace_clients_lock);
774 dev_err(dev, "%s: Can't find device in list\n",
779 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
780 static DEVICE_ATTR(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device);
782 static struct attribute *i2c_adapter_attrs[] = {
784 &dev_attr_new_device.attr,
785 &dev_attr_delete_device.attr,
789 static struct attribute_group i2c_adapter_attr_group = {
790 .attrs = i2c_adapter_attrs,
793 static const struct attribute_group *i2c_adapter_attr_groups[] = {
794 &i2c_adapter_attr_group,
798 struct device_type i2c_adapter_type = {
799 .groups = i2c_adapter_attr_groups,
800 .release = i2c_adapter_dev_release,
802 EXPORT_SYMBOL_GPL(i2c_adapter_type);
804 #ifdef CONFIG_I2C_COMPAT
805 static struct class_compat *i2c_adapter_compat_class;
808 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
810 struct i2c_devinfo *devinfo;
812 down_read(&__i2c_board_lock);
813 list_for_each_entry(devinfo, &__i2c_board_list, list) {
814 if (devinfo->busnum == adapter->nr
815 && !i2c_new_device(adapter,
816 &devinfo->board_info))
817 dev_err(&adapter->dev,
818 "Can't create device at 0x%02x\n",
819 devinfo->board_info.addr);
821 up_read(&__i2c_board_lock);
824 static int i2c_do_add_adapter(struct i2c_driver *driver,
825 struct i2c_adapter *adap)
827 /* Detect supported devices on that bus, and instantiate them */
828 i2c_detect(adap, driver);
830 /* Let legacy drivers scan this bus for matching devices */
831 if (driver->attach_adapter) {
832 /* We ignore the return code; if it fails, too bad */
833 driver->attach_adapter(adap);
838 static int __process_new_adapter(struct device_driver *d, void *data)
840 return i2c_do_add_adapter(to_i2c_driver(d), data);
843 static int i2c_register_adapter(struct i2c_adapter *adap)
847 /* Can't register until after driver model init */
848 if (unlikely(WARN_ON(!i2c_bus_type.p))) {
853 rt_mutex_init(&adap->bus_lock);
854 mutex_init(&adap->userspace_clients_lock);
855 INIT_LIST_HEAD(&adap->userspace_clients);
857 /* Set default timeout to 1 second if not already set */
858 if (adap->timeout == 0)
861 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
862 adap->dev.bus = &i2c_bus_type;
863 adap->dev.type = &i2c_adapter_type;
864 res = device_register(&adap->dev);
868 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
870 #ifdef CONFIG_I2C_COMPAT
871 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
875 "Failed to create compatibility class link\n");
878 /* create pre-declared device nodes */
879 if (adap->nr < __i2c_first_dynamic_bus_num)
880 i2c_scan_static_board_info(adap);
883 mutex_lock(&core_lock);
884 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
885 mutex_unlock(&core_lock);
890 mutex_lock(&core_lock);
891 idr_remove(&i2c_adapter_idr, adap->nr);
892 mutex_unlock(&core_lock);
897 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
898 * @adapter: the adapter to add
901 * This routine is used to declare an I2C adapter when its bus number
902 * doesn't matter. Examples: for I2C adapters dynamically added by
903 * USB links or PCI plugin cards.
905 * When this returns zero, a new bus number was allocated and stored
906 * in adap->nr, and the specified adapter became available for clients.
907 * Otherwise, a negative errno value is returned.
909 int i2c_add_adapter(struct i2c_adapter *adapter)
914 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
917 mutex_lock(&core_lock);
918 /* "above" here means "above or equal to", sigh */
919 res = idr_get_new_above(&i2c_adapter_idr, adapter,
920 __i2c_first_dynamic_bus_num, &id);
921 mutex_unlock(&core_lock);
930 return i2c_register_adapter(adapter);
932 EXPORT_SYMBOL(i2c_add_adapter);
935 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
936 * @adap: the adapter to register (with adap->nr initialized)
939 * This routine is used to declare an I2C adapter when its bus number
940 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
941 * or otherwise built in to the system's mainboard, and where i2c_board_info
942 * is used to properly configure I2C devices.
944 * If no devices have pre-been declared for this bus, then be sure to
945 * register the adapter before any dynamically allocated ones. Otherwise
946 * the required bus ID may not be available.
948 * When this returns zero, the specified adapter became available for
949 * clients using the bus number provided in adap->nr. Also, the table
950 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
951 * and the appropriate driver model device nodes are created. Otherwise, a
952 * negative errno value is returned.
954 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
959 if (adap->nr & ~MAX_ID_MASK)
963 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
966 mutex_lock(&core_lock);
967 /* "above" here means "above or equal to", sigh;
968 * we need the "equal to" result to force the result
970 status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
971 if (status == 0 && id != adap->nr) {
973 idr_remove(&i2c_adapter_idr, id);
975 mutex_unlock(&core_lock);
976 if (status == -EAGAIN)
980 status = i2c_register_adapter(adap);
983 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
985 static int i2c_do_del_adapter(struct i2c_driver *driver,
986 struct i2c_adapter *adapter)
988 struct i2c_client *client, *_n;
991 /* Remove the devices we created ourselves as the result of hardware
992 * probing (using a driver's detect method) */
993 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
994 if (client->adapter == adapter) {
995 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
996 client->name, client->addr);
997 list_del(&client->detected);
998 i2c_unregister_device(client);
1002 if (!driver->detach_adapter)
1004 res = driver->detach_adapter(adapter);
1006 dev_err(&adapter->dev, "detach_adapter failed (%d) "
1007 "for driver [%s]\n", res, driver->driver.name);
1011 static int __unregister_client(struct device *dev, void *dummy)
1013 struct i2c_client *client = i2c_verify_client(dev);
1015 i2c_unregister_device(client);
1019 static int __process_removed_adapter(struct device_driver *d, void *data)
1021 return i2c_do_del_adapter(to_i2c_driver(d), data);
1025 * i2c_del_adapter - unregister I2C adapter
1026 * @adap: the adapter being unregistered
1027 * Context: can sleep
1029 * This unregisters an I2C adapter which was previously registered
1030 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1032 int i2c_del_adapter(struct i2c_adapter *adap)
1035 struct i2c_adapter *found;
1036 struct i2c_client *client, *next;
1038 /* First make sure that this adapter was ever added */
1039 mutex_lock(&core_lock);
1040 found = idr_find(&i2c_adapter_idr, adap->nr);
1041 mutex_unlock(&core_lock);
1042 if (found != adap) {
1043 pr_debug("i2c-core: attempting to delete unregistered "
1044 "adapter [%s]\n", adap->name);
1048 /* Tell drivers about this removal */
1049 mutex_lock(&core_lock);
1050 res = bus_for_each_drv(&i2c_bus_type, NULL, adap,
1051 __process_removed_adapter);
1052 mutex_unlock(&core_lock);
1056 /* Remove devices instantiated from sysfs */
1057 mutex_lock(&adap->userspace_clients_lock);
1058 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1060 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1062 list_del(&client->detected);
1063 i2c_unregister_device(client);
1065 mutex_unlock(&adap->userspace_clients_lock);
1067 /* Detach any active clients. This can't fail, thus we do not
1068 checking the returned value. */
1069 res = device_for_each_child(&adap->dev, NULL, __unregister_client);
1071 #ifdef CONFIG_I2C_COMPAT
1072 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1076 /* device name is gone after device_unregister */
1077 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1079 /* clean up the sysfs representation */
1080 init_completion(&adap->dev_released);
1081 device_unregister(&adap->dev);
1083 /* wait for sysfs to drop all references */
1084 wait_for_completion(&adap->dev_released);
1087 mutex_lock(&core_lock);
1088 idr_remove(&i2c_adapter_idr, adap->nr);
1089 mutex_unlock(&core_lock);
1091 /* Clear the device structure in case this adapter is ever going to be
1093 memset(&adap->dev, 0, sizeof(adap->dev));
1097 EXPORT_SYMBOL(i2c_del_adapter);
1100 /* ------------------------------------------------------------------------- */
1102 static int __process_new_driver(struct device *dev, void *data)
1104 if (dev->type != &i2c_adapter_type)
1106 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1110 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1111 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1114 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1118 /* Can't register until after driver model init */
1119 if (unlikely(WARN_ON(!i2c_bus_type.p)))
1122 /* add the driver to the list of i2c drivers in the driver core */
1123 driver->driver.owner = owner;
1124 driver->driver.bus = &i2c_bus_type;
1126 /* When registration returns, the driver core
1127 * will have called probe() for all matching-but-unbound devices.
1129 res = driver_register(&driver->driver);
1133 pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
1135 INIT_LIST_HEAD(&driver->clients);
1136 /* Walk the adapters that are already present */
1137 mutex_lock(&core_lock);
1138 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_new_driver);
1139 mutex_unlock(&core_lock);
1143 EXPORT_SYMBOL(i2c_register_driver);
1145 static int __process_removed_driver(struct device *dev, void *data)
1147 if (dev->type != &i2c_adapter_type)
1149 return i2c_do_del_adapter(data, to_i2c_adapter(dev));
1153 * i2c_del_driver - unregister I2C driver
1154 * @driver: the driver being unregistered
1155 * Context: can sleep
1157 void i2c_del_driver(struct i2c_driver *driver)
1159 mutex_lock(&core_lock);
1160 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_removed_driver);
1161 mutex_unlock(&core_lock);
1163 driver_unregister(&driver->driver);
1164 pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
1166 EXPORT_SYMBOL(i2c_del_driver);
1168 /* ------------------------------------------------------------------------- */
1171 * i2c_use_client - increments the reference count of the i2c client structure
1172 * @client: the client being referenced
1174 * Each live reference to a client should be refcounted. The driver model does
1175 * that automatically as part of driver binding, so that most drivers don't
1176 * need to do this explicitly: they hold a reference until they're unbound
1179 * A pointer to the client with the incremented reference counter is returned.
1181 struct i2c_client *i2c_use_client(struct i2c_client *client)
1183 if (client && get_device(&client->dev))
1187 EXPORT_SYMBOL(i2c_use_client);
1190 * i2c_release_client - release a use of the i2c client structure
1191 * @client: the client being no longer referenced
1193 * Must be called when a user of a client is finished with it.
1195 void i2c_release_client(struct i2c_client *client)
1198 put_device(&client->dev);
1200 EXPORT_SYMBOL(i2c_release_client);
1202 struct i2c_cmd_arg {
1207 static int i2c_cmd(struct device *dev, void *_arg)
1209 struct i2c_client *client = i2c_verify_client(dev);
1210 struct i2c_cmd_arg *arg = _arg;
1212 if (client && client->driver && client->driver->command)
1213 client->driver->command(client, arg->cmd, arg->arg);
1217 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1219 struct i2c_cmd_arg cmd_arg;
1223 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1225 EXPORT_SYMBOL(i2c_clients_command);
1227 static int __init i2c_init(void)
1231 retval = bus_register(&i2c_bus_type);
1234 #ifdef CONFIG_I2C_COMPAT
1235 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1236 if (!i2c_adapter_compat_class) {
1241 retval = i2c_add_driver(&dummy_driver);
1247 #ifdef CONFIG_I2C_COMPAT
1248 class_compat_unregister(i2c_adapter_compat_class);
1251 bus_unregister(&i2c_bus_type);
1255 static void __exit i2c_exit(void)
1257 i2c_del_driver(&dummy_driver);
1258 #ifdef CONFIG_I2C_COMPAT
1259 class_compat_unregister(i2c_adapter_compat_class);
1261 bus_unregister(&i2c_bus_type);
1264 /* We must initialize early, because some subsystems register i2c drivers
1265 * in subsys_initcall() code, but are linked (and initialized) before i2c.
1267 postcore_initcall(i2c_init);
1268 module_exit(i2c_exit);
1270 /* ----------------------------------------------------
1271 * the functional interface to the i2c busses.
1272 * ----------------------------------------------------
1276 * i2c_transfer - execute a single or combined I2C message
1277 * @adap: Handle to I2C bus
1278 * @msgs: One or more messages to execute before STOP is issued to
1279 * terminate the operation; each message begins with a START.
1280 * @num: Number of messages to be executed.
1282 * Returns negative errno, else the number of messages executed.
1284 * Note that there is no requirement that each message be sent to
1285 * the same slave address, although that is the most common model.
1287 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1289 unsigned long orig_jiffies;
1292 /* REVISIT the fault reporting model here is weak:
1294 * - When we get an error after receiving N bytes from a slave,
1295 * there is no way to report "N".
1297 * - When we get a NAK after transmitting N bytes to a slave,
1298 * there is no way to report "N" ... or to let the master
1299 * continue executing the rest of this combined message, if
1300 * that's the appropriate response.
1302 * - When for example "num" is two and we successfully complete
1303 * the first message but get an error part way through the
1304 * second, it's unclear whether that should be reported as
1305 * one (discarding status on the second message) or errno
1306 * (discarding status on the first one).
1309 if (adap->algo->master_xfer) {
1311 for (ret = 0; ret < num; ret++) {
1312 dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
1313 "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
1314 ? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
1315 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1319 if (in_atomic() || irqs_disabled()) {
1320 ret = i2c_trylock_adapter(adap);
1322 /* I2C activity is ongoing. */
1325 i2c_lock_adapter(adap);
1328 /* Retry automatically on arbitration loss */
1329 orig_jiffies = jiffies;
1330 for (ret = 0, try = 0; try <= adap->retries; try++) {
1331 ret = adap->algo->master_xfer(adap, msgs, num);
1334 if (time_after(jiffies, orig_jiffies + adap->timeout))
1337 i2c_unlock_adapter(adap);
1341 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1345 EXPORT_SYMBOL(i2c_transfer);
1348 * i2c_master_send - issue a single I2C message in master transmit mode
1349 * @client: Handle to slave device
1350 * @buf: Data that will be written to the slave
1351 * @count: How many bytes to write, must be less than 64k since msg.len is u16
1353 * Returns negative errno, or else the number of bytes written.
1355 int i2c_master_send(struct i2c_client *client, const char *buf, int count)
1358 struct i2c_adapter *adap = client->adapter;
1361 msg.addr = client->addr;
1362 msg.flags = client->flags & I2C_M_TEN;
1364 msg.buf = (char *)buf;
1366 ret = i2c_transfer(adap, &msg, 1);
1368 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1369 transmitted, else error code. */
1370 return (ret == 1) ? count : ret;
1372 EXPORT_SYMBOL(i2c_master_send);
1375 * i2c_master_recv - issue a single I2C message in master receive mode
1376 * @client: Handle to slave device
1377 * @buf: Where to store data read from slave
1378 * @count: How many bytes to read, must be less than 64k since msg.len is u16
1380 * Returns negative errno, or else the number of bytes read.
1382 int i2c_master_recv(struct i2c_client *client, char *buf, int count)
1384 struct i2c_adapter *adap = client->adapter;
1388 msg.addr = client->addr;
1389 msg.flags = client->flags & I2C_M_TEN;
1390 msg.flags |= I2C_M_RD;
1394 ret = i2c_transfer(adap, &msg, 1);
1396 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1397 transmitted, else error code. */
1398 return (ret == 1) ? count : ret;
1400 EXPORT_SYMBOL(i2c_master_recv);
1402 /* ----------------------------------------------------
1403 * the i2c address scanning function
1404 * Will not work for 10-bit addresses!
1405 * ----------------------------------------------------
1409 * Legacy default probe function, mostly relevant for SMBus. The default
1410 * probe method is a quick write, but it is known to corrupt the 24RF08
1411 * EEPROMs due to a state machine bug, and could also irreversibly
1412 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
1413 * we use a short byte read instead. Also, some bus drivers don't implement
1414 * quick write, so we fallback to a byte read in that case too.
1415 * On x86, there is another special case for FSC hardware monitoring chips,
1416 * which want regular byte reads (address 0x73.) Fortunately, these are the
1417 * only known chips using this I2C address on PC hardware.
1418 * Returns 1 if probe succeeded, 0 if not.
1420 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
1423 union i2c_smbus_data dummy;
1426 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
1427 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
1428 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1429 I2C_SMBUS_BYTE_DATA, &dummy);
1432 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
1433 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
1434 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
1435 I2C_SMBUS_QUICK, NULL);
1436 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
1437 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1438 I2C_SMBUS_BYTE, &dummy);
1440 dev_warn(&adap->dev, "No suitable probing method supported\n");
1447 static int i2c_detect_address(struct i2c_client *temp_client,
1448 struct i2c_driver *driver)
1450 struct i2c_board_info info;
1451 struct i2c_adapter *adapter = temp_client->adapter;
1452 int addr = temp_client->addr;
1455 /* Make sure the address is valid */
1456 err = i2c_check_addr_validity(addr);
1458 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
1463 /* Skip if already in use */
1464 if (i2c_check_addr_busy(adapter, addr))
1467 /* Make sure there is something at this address */
1468 if (!i2c_default_probe(adapter, addr))
1471 /* Finally call the custom detection function */
1472 memset(&info, 0, sizeof(struct i2c_board_info));
1474 err = driver->detect(temp_client, &info);
1476 /* -ENODEV is returned if the detection fails. We catch it
1477 here as this isn't an error. */
1478 return err == -ENODEV ? 0 : err;
1481 /* Consistency check */
1482 if (info.type[0] == '\0') {
1483 dev_err(&adapter->dev, "%s detection function provided "
1484 "no name for 0x%x\n", driver->driver.name,
1487 struct i2c_client *client;
1489 /* Detection succeeded, instantiate the device */
1490 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
1491 info.type, info.addr);
1492 client = i2c_new_device(adapter, &info);
1494 list_add_tail(&client->detected, &driver->clients);
1496 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
1497 info.type, info.addr);
1502 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
1504 const unsigned short *address_list;
1505 struct i2c_client *temp_client;
1507 int adap_id = i2c_adapter_id(adapter);
1509 address_list = driver->address_list;
1510 if (!driver->detect || !address_list)
1513 /* Set up a temporary client to help detect callback */
1514 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
1517 temp_client->adapter = adapter;
1519 /* Stop here if the classes do not match */
1520 if (!(adapter->class & driver->class))
1523 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
1524 dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
1525 "addr 0x%02x\n", adap_id, address_list[i]);
1526 temp_client->addr = address_list[i];
1527 err = i2c_detect_address(temp_client, driver);
1537 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
1539 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1540 I2C_SMBUS_QUICK, NULL) >= 0;
1542 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
1545 i2c_new_probed_device(struct i2c_adapter *adap,
1546 struct i2c_board_info *info,
1547 unsigned short const *addr_list,
1548 int (*probe)(struct i2c_adapter *, unsigned short addr))
1553 probe = i2c_default_probe;
1555 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
1556 /* Check address validity */
1557 if (i2c_check_addr_validity(addr_list[i]) < 0) {
1558 dev_warn(&adap->dev, "Invalid 7-bit address "
1559 "0x%02x\n", addr_list[i]);
1563 /* Check address availability */
1564 if (i2c_check_addr_busy(adap, addr_list[i])) {
1565 dev_dbg(&adap->dev, "Address 0x%02x already in "
1566 "use, not probing\n", addr_list[i]);
1570 /* Test address responsiveness */
1571 if (probe(adap, addr_list[i]))
1575 if (addr_list[i] == I2C_CLIENT_END) {
1576 dev_dbg(&adap->dev, "Probing failed, no device found\n");
1580 info->addr = addr_list[i];
1581 return i2c_new_device(adap, info);
1583 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
1585 struct i2c_adapter *i2c_get_adapter(int id)
1587 struct i2c_adapter *adapter;
1589 mutex_lock(&core_lock);
1590 adapter = idr_find(&i2c_adapter_idr, id);
1591 if (adapter && !try_module_get(adapter->owner))
1594 mutex_unlock(&core_lock);
1597 EXPORT_SYMBOL(i2c_get_adapter);
1599 void i2c_put_adapter(struct i2c_adapter *adap)
1601 module_put(adap->owner);
1603 EXPORT_SYMBOL(i2c_put_adapter);
1605 /* The SMBus parts */
1607 #define POLY (0x1070U << 3)
1608 static u8 crc8(u16 data)
1612 for (i = 0; i < 8; i++) {
1617 return (u8)(data >> 8);
1620 /* Incremental CRC8 over count bytes in the array pointed to by p */
1621 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
1625 for (i = 0; i < count; i++)
1626 crc = crc8((crc ^ p[i]) << 8);
1630 /* Assume a 7-bit address, which is reasonable for SMBus */
1631 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
1633 /* The address will be sent first */
1634 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
1635 pec = i2c_smbus_pec(pec, &addr, 1);
1637 /* The data buffer follows */
1638 return i2c_smbus_pec(pec, msg->buf, msg->len);
1641 /* Used for write only transactions */
1642 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
1644 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
1648 /* Return <0 on CRC error
1649 If there was a write before this read (most cases) we need to take the
1650 partial CRC from the write part into account.
1651 Note that this function does modify the message (we need to decrease the
1652 message length to hide the CRC byte from the caller). */
1653 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
1655 u8 rpec = msg->buf[--msg->len];
1656 cpec = i2c_smbus_msg_pec(cpec, msg);
1659 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
1667 * i2c_smbus_read_byte - SMBus "receive byte" protocol
1668 * @client: Handle to slave device
1670 * This executes the SMBus "receive byte" protocol, returning negative errno
1671 * else the byte received from the device.
1673 s32 i2c_smbus_read_byte(struct i2c_client *client)
1675 union i2c_smbus_data data;
1678 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1680 I2C_SMBUS_BYTE, &data);
1681 return (status < 0) ? status : data.byte;
1683 EXPORT_SYMBOL(i2c_smbus_read_byte);
1686 * i2c_smbus_write_byte - SMBus "send byte" protocol
1687 * @client: Handle to slave device
1688 * @value: Byte to be sent
1690 * This executes the SMBus "send byte" protocol, returning negative errno
1691 * else zero on success.
1693 s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value)
1695 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1696 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
1698 EXPORT_SYMBOL(i2c_smbus_write_byte);
1701 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
1702 * @client: Handle to slave device
1703 * @command: Byte interpreted by slave
1705 * This executes the SMBus "read byte" protocol, returning negative errno
1706 * else a data byte received from the device.
1708 s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
1710 union i2c_smbus_data data;
1713 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1714 I2C_SMBUS_READ, command,
1715 I2C_SMBUS_BYTE_DATA, &data);
1716 return (status < 0) ? status : data.byte;
1718 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
1721 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
1722 * @client: Handle to slave device
1723 * @command: Byte interpreted by slave
1724 * @value: Byte being written
1726 * This executes the SMBus "write byte" protocol, returning negative errno
1727 * else zero on success.
1729 s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value)
1731 union i2c_smbus_data data;
1733 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1734 I2C_SMBUS_WRITE, command,
1735 I2C_SMBUS_BYTE_DATA, &data);
1737 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
1740 * i2c_smbus_read_word_data - SMBus "read word" protocol
1741 * @client: Handle to slave device
1742 * @command: Byte interpreted by slave
1744 * This executes the SMBus "read word" protocol, returning negative errno
1745 * else a 16-bit unsigned "word" received from the device.
1747 s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
1749 union i2c_smbus_data data;
1752 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1753 I2C_SMBUS_READ, command,
1754 I2C_SMBUS_WORD_DATA, &data);
1755 return (status < 0) ? status : data.word;
1757 EXPORT_SYMBOL(i2c_smbus_read_word_data);
1760 * i2c_smbus_write_word_data - SMBus "write word" protocol
1761 * @client: Handle to slave device
1762 * @command: Byte interpreted by slave
1763 * @value: 16-bit "word" being written
1765 * This executes the SMBus "write word" protocol, returning negative errno
1766 * else zero on success.
1768 s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
1770 union i2c_smbus_data data;
1772 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1773 I2C_SMBUS_WRITE, command,
1774 I2C_SMBUS_WORD_DATA, &data);
1776 EXPORT_SYMBOL(i2c_smbus_write_word_data);
1779 * i2c_smbus_process_call - SMBus "process call" protocol
1780 * @client: Handle to slave device
1781 * @command: Byte interpreted by slave
1782 * @value: 16-bit "word" being written
1784 * This executes the SMBus "process call" protocol, returning negative errno
1785 * else a 16-bit unsigned "word" received from the device.
1787 s32 i2c_smbus_process_call(struct i2c_client *client, u8 command, u16 value)
1789 union i2c_smbus_data data;
1793 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1794 I2C_SMBUS_WRITE, command,
1795 I2C_SMBUS_PROC_CALL, &data);
1796 return (status < 0) ? status : data.word;
1798 EXPORT_SYMBOL(i2c_smbus_process_call);
1801 * i2c_smbus_read_block_data - SMBus "block read" protocol
1802 * @client: Handle to slave device
1803 * @command: Byte interpreted by slave
1804 * @values: Byte array into which data will be read; big enough to hold
1805 * the data returned by the slave. SMBus allows at most 32 bytes.
1807 * This executes the SMBus "block read" protocol, returning negative errno
1808 * else the number of data bytes in the slave's response.
1810 * Note that using this function requires that the client's adapter support
1811 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
1812 * support this; its emulation through I2C messaging relies on a specific
1813 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
1815 s32 i2c_smbus_read_block_data(struct i2c_client *client, u8 command,
1818 union i2c_smbus_data data;
1821 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1822 I2C_SMBUS_READ, command,
1823 I2C_SMBUS_BLOCK_DATA, &data);
1827 memcpy(values, &data.block[1], data.block[0]);
1828 return data.block[0];
1830 EXPORT_SYMBOL(i2c_smbus_read_block_data);
1833 * i2c_smbus_write_block_data - SMBus "block write" protocol
1834 * @client: Handle to slave device
1835 * @command: Byte interpreted by slave
1836 * @length: Size of data block; SMBus allows at most 32 bytes
1837 * @values: Byte array which will be written.
1839 * This executes the SMBus "block write" protocol, returning negative errno
1840 * else zero on success.
1842 s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
1843 u8 length, const u8 *values)
1845 union i2c_smbus_data data;
1847 if (length > I2C_SMBUS_BLOCK_MAX)
1848 length = I2C_SMBUS_BLOCK_MAX;
1849 data.block[0] = length;
1850 memcpy(&data.block[1], values, length);
1851 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1852 I2C_SMBUS_WRITE, command,
1853 I2C_SMBUS_BLOCK_DATA, &data);
1855 EXPORT_SYMBOL(i2c_smbus_write_block_data);
1857 /* Returns the number of read bytes */
1858 s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
1859 u8 length, u8 *values)
1861 union i2c_smbus_data data;
1864 if (length > I2C_SMBUS_BLOCK_MAX)
1865 length = I2C_SMBUS_BLOCK_MAX;
1866 data.block[0] = length;
1867 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1868 I2C_SMBUS_READ, command,
1869 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1873 memcpy(values, &data.block[1], data.block[0]);
1874 return data.block[0];
1876 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
1878 s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command,
1879 u8 length, const u8 *values)
1881 union i2c_smbus_data data;
1883 if (length > I2C_SMBUS_BLOCK_MAX)
1884 length = I2C_SMBUS_BLOCK_MAX;
1885 data.block[0] = length;
1886 memcpy(data.block + 1, values, length);
1887 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1888 I2C_SMBUS_WRITE, command,
1889 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1891 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
1893 /* Simulate a SMBus command using the i2c protocol
1894 No checking of parameters is done! */
1895 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
1896 unsigned short flags,
1897 char read_write, u8 command, int size,
1898 union i2c_smbus_data *data)
1900 /* So we need to generate a series of msgs. In the case of writing, we
1901 need to use only one message; when reading, we need two. We initialize
1902 most things with sane defaults, to keep the code below somewhat
1904 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
1905 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
1906 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
1907 struct i2c_msg msg[2] = { { addr, flags, 1, msgbuf0 },
1908 { addr, flags | I2C_M_RD, 0, msgbuf1 }
1914 msgbuf0[0] = command;
1916 case I2C_SMBUS_QUICK:
1918 /* Special case: The read/write field is used as data */
1919 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
1923 case I2C_SMBUS_BYTE:
1924 if (read_write == I2C_SMBUS_READ) {
1925 /* Special case: only a read! */
1926 msg[0].flags = I2C_M_RD | flags;
1930 case I2C_SMBUS_BYTE_DATA:
1931 if (read_write == I2C_SMBUS_READ)
1935 msgbuf0[1] = data->byte;
1938 case I2C_SMBUS_WORD_DATA:
1939 if (read_write == I2C_SMBUS_READ)
1943 msgbuf0[1] = data->word & 0xff;
1944 msgbuf0[2] = data->word >> 8;
1947 case I2C_SMBUS_PROC_CALL:
1948 num = 2; /* Special case */
1949 read_write = I2C_SMBUS_READ;
1952 msgbuf0[1] = data->word & 0xff;
1953 msgbuf0[2] = data->word >> 8;
1955 case I2C_SMBUS_BLOCK_DATA:
1956 if (read_write == I2C_SMBUS_READ) {
1957 msg[1].flags |= I2C_M_RECV_LEN;
1958 msg[1].len = 1; /* block length will be added by
1959 the underlying bus driver */
1961 msg[0].len = data->block[0] + 2;
1962 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
1963 dev_err(&adapter->dev,
1964 "Invalid block write size %d\n",
1968 for (i = 1; i < msg[0].len; i++)
1969 msgbuf0[i] = data->block[i-1];
1972 case I2C_SMBUS_BLOCK_PROC_CALL:
1973 num = 2; /* Another special case */
1974 read_write = I2C_SMBUS_READ;
1975 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
1976 dev_err(&adapter->dev,
1977 "Invalid block write size %d\n",
1981 msg[0].len = data->block[0] + 2;
1982 for (i = 1; i < msg[0].len; i++)
1983 msgbuf0[i] = data->block[i-1];
1984 msg[1].flags |= I2C_M_RECV_LEN;
1985 msg[1].len = 1; /* block length will be added by
1986 the underlying bus driver */
1988 case I2C_SMBUS_I2C_BLOCK_DATA:
1989 if (read_write == I2C_SMBUS_READ) {
1990 msg[1].len = data->block[0];
1992 msg[0].len = data->block[0] + 1;
1993 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
1994 dev_err(&adapter->dev,
1995 "Invalid block write size %d\n",
1999 for (i = 1; i <= data->block[0]; i++)
2000 msgbuf0[i] = data->block[i];
2004 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
2008 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
2009 && size != I2C_SMBUS_I2C_BLOCK_DATA);
2011 /* Compute PEC if first message is a write */
2012 if (!(msg[0].flags & I2C_M_RD)) {
2013 if (num == 1) /* Write only */
2014 i2c_smbus_add_pec(&msg[0]);
2015 else /* Write followed by read */
2016 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
2018 /* Ask for PEC if last message is a read */
2019 if (msg[num-1].flags & I2C_M_RD)
2023 status = i2c_transfer(adapter, msg, num);
2027 /* Check PEC if last message is a read */
2028 if (i && (msg[num-1].flags & I2C_M_RD)) {
2029 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
2034 if (read_write == I2C_SMBUS_READ)
2036 case I2C_SMBUS_BYTE:
2037 data->byte = msgbuf0[0];
2039 case I2C_SMBUS_BYTE_DATA:
2040 data->byte = msgbuf1[0];
2042 case I2C_SMBUS_WORD_DATA:
2043 case I2C_SMBUS_PROC_CALL:
2044 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
2046 case I2C_SMBUS_I2C_BLOCK_DATA:
2047 for (i = 0; i < data->block[0]; i++)
2048 data->block[i+1] = msgbuf1[i];
2050 case I2C_SMBUS_BLOCK_DATA:
2051 case I2C_SMBUS_BLOCK_PROC_CALL:
2052 for (i = 0; i < msgbuf1[0] + 1; i++)
2053 data->block[i] = msgbuf1[i];
2060 * i2c_smbus_xfer - execute SMBus protocol operations
2061 * @adapter: Handle to I2C bus
2062 * @addr: Address of SMBus slave on that bus
2063 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
2064 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
2065 * @command: Byte interpreted by slave, for protocols which use such bytes
2066 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
2067 * @data: Data to be read or written
2069 * This executes an SMBus protocol operation, and returns a negative
2070 * errno code else zero on success.
2072 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
2073 char read_write, u8 command, int protocol,
2074 union i2c_smbus_data *data)
2076 unsigned long orig_jiffies;
2080 flags &= I2C_M_TEN | I2C_CLIENT_PEC;
2082 if (adapter->algo->smbus_xfer) {
2083 i2c_lock_adapter(adapter);
2085 /* Retry automatically on arbitration loss */
2086 orig_jiffies = jiffies;
2087 for (res = 0, try = 0; try <= adapter->retries; try++) {
2088 res = adapter->algo->smbus_xfer(adapter, addr, flags,
2089 read_write, command,
2093 if (time_after(jiffies,
2094 orig_jiffies + adapter->timeout))
2097 i2c_unlock_adapter(adapter);
2099 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
2100 command, protocol, data);
2104 EXPORT_SYMBOL(i2c_smbus_xfer);
2106 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2107 MODULE_DESCRIPTION("I2C-Bus main module");
2108 MODULE_LICENSE("GPL");