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 memset(&info, 0, sizeof(struct i2c_board_info));
688 blank = strchr(buf, ' ');
690 dev_err(dev, "%s: Missing parameters\n", "new_device");
693 if (blank - buf > I2C_NAME_SIZE - 1) {
694 dev_err(dev, "%s: Invalid device name\n", "new_device");
697 memcpy(info.type, buf, blank - buf);
699 /* Parse remaining parameters, reject extra parameters */
700 res = sscanf(++blank, "%hi%c", &info.addr, &end);
702 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
705 if (res > 1 && end != '\n') {
706 dev_err(dev, "%s: Extra parameters\n", "new_device");
710 client = i2c_new_device(adap, &info);
714 /* Keep track of the added device */
715 mutex_lock(&adap->userspace_clients_lock);
716 list_add_tail(&client->detected, &adap->userspace_clients);
717 mutex_unlock(&adap->userspace_clients_lock);
718 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
719 info.type, info.addr);
725 * And of course let the users delete the devices they instantiated, if
726 * they got it wrong. This interface can only be used to delete devices
727 * instantiated by i2c_sysfs_new_device above. This guarantees that we
728 * don't delete devices to which some kernel code still has references.
730 * Parameter checking may look overzealous, but we really don't want
731 * the user to delete the wrong device.
734 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
735 const char *buf, size_t count)
737 struct i2c_adapter *adap = to_i2c_adapter(dev);
738 struct i2c_client *client, *next;
743 /* Parse parameters, reject extra parameters */
744 res = sscanf(buf, "%hi%c", &addr, &end);
746 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
749 if (res > 1 && end != '\n') {
750 dev_err(dev, "%s: Extra parameters\n", "delete_device");
754 /* Make sure the device was added through sysfs */
756 mutex_lock(&adap->userspace_clients_lock);
757 list_for_each_entry_safe(client, next, &adap->userspace_clients,
759 if (client->addr == addr) {
760 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
761 "delete_device", client->name, client->addr);
763 list_del(&client->detected);
764 i2c_unregister_device(client);
769 mutex_unlock(&adap->userspace_clients_lock);
772 dev_err(dev, "%s: Can't find device in list\n",
777 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
778 static DEVICE_ATTR(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device);
780 static struct attribute *i2c_adapter_attrs[] = {
782 &dev_attr_new_device.attr,
783 &dev_attr_delete_device.attr,
787 static struct attribute_group i2c_adapter_attr_group = {
788 .attrs = i2c_adapter_attrs,
791 static const struct attribute_group *i2c_adapter_attr_groups[] = {
792 &i2c_adapter_attr_group,
796 struct device_type i2c_adapter_type = {
797 .groups = i2c_adapter_attr_groups,
798 .release = i2c_adapter_dev_release,
800 EXPORT_SYMBOL_GPL(i2c_adapter_type);
802 #ifdef CONFIG_I2C_COMPAT
803 static struct class_compat *i2c_adapter_compat_class;
806 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
808 struct i2c_devinfo *devinfo;
810 down_read(&__i2c_board_lock);
811 list_for_each_entry(devinfo, &__i2c_board_list, list) {
812 if (devinfo->busnum == adapter->nr
813 && !i2c_new_device(adapter,
814 &devinfo->board_info))
815 dev_err(&adapter->dev,
816 "Can't create device at 0x%02x\n",
817 devinfo->board_info.addr);
819 up_read(&__i2c_board_lock);
822 static int i2c_do_add_adapter(struct i2c_driver *driver,
823 struct i2c_adapter *adap)
825 /* Detect supported devices on that bus, and instantiate them */
826 i2c_detect(adap, driver);
828 /* Let legacy drivers scan this bus for matching devices */
829 if (driver->attach_adapter) {
830 /* We ignore the return code; if it fails, too bad */
831 driver->attach_adapter(adap);
836 static int __process_new_adapter(struct device_driver *d, void *data)
838 return i2c_do_add_adapter(to_i2c_driver(d), data);
841 static int i2c_register_adapter(struct i2c_adapter *adap)
845 /* Can't register until after driver model init */
846 if (unlikely(WARN_ON(!i2c_bus_type.p))) {
852 if (unlikely(adap->name[0] == '\0')) {
853 pr_err("i2c-core: Attempt to register an adapter with "
857 if (unlikely(!adap->algo)) {
858 pr_err("i2c-core: Attempt to register adapter '%s' with "
859 "no algo!\n", adap->name);
863 rt_mutex_init(&adap->bus_lock);
864 mutex_init(&adap->userspace_clients_lock);
865 INIT_LIST_HEAD(&adap->userspace_clients);
867 /* Set default timeout to 1 second if not already set */
868 if (adap->timeout == 0)
871 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
872 adap->dev.bus = &i2c_bus_type;
873 adap->dev.type = &i2c_adapter_type;
874 res = device_register(&adap->dev);
878 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
880 #ifdef CONFIG_I2C_COMPAT
881 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
885 "Failed to create compatibility class link\n");
888 /* create pre-declared device nodes */
889 if (adap->nr < __i2c_first_dynamic_bus_num)
890 i2c_scan_static_board_info(adap);
893 mutex_lock(&core_lock);
894 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
895 mutex_unlock(&core_lock);
900 mutex_lock(&core_lock);
901 idr_remove(&i2c_adapter_idr, adap->nr);
902 mutex_unlock(&core_lock);
907 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
908 * @adapter: the adapter to add
911 * This routine is used to declare an I2C adapter when its bus number
912 * doesn't matter. Examples: for I2C adapters dynamically added by
913 * USB links or PCI plugin cards.
915 * When this returns zero, a new bus number was allocated and stored
916 * in adap->nr, and the specified adapter became available for clients.
917 * Otherwise, a negative errno value is returned.
919 int i2c_add_adapter(struct i2c_adapter *adapter)
924 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
927 mutex_lock(&core_lock);
928 /* "above" here means "above or equal to", sigh */
929 res = idr_get_new_above(&i2c_adapter_idr, adapter,
930 __i2c_first_dynamic_bus_num, &id);
931 mutex_unlock(&core_lock);
940 return i2c_register_adapter(adapter);
942 EXPORT_SYMBOL(i2c_add_adapter);
945 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
946 * @adap: the adapter to register (with adap->nr initialized)
949 * This routine is used to declare an I2C adapter when its bus number
950 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
951 * or otherwise built in to the system's mainboard, and where i2c_board_info
952 * is used to properly configure I2C devices.
954 * If no devices have pre-been declared for this bus, then be sure to
955 * register the adapter before any dynamically allocated ones. Otherwise
956 * the required bus ID may not be available.
958 * When this returns zero, the specified adapter became available for
959 * clients using the bus number provided in adap->nr. Also, the table
960 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
961 * and the appropriate driver model device nodes are created. Otherwise, a
962 * negative errno value is returned.
964 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
969 if (adap->nr & ~MAX_ID_MASK)
973 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
976 mutex_lock(&core_lock);
977 /* "above" here means "above or equal to", sigh;
978 * we need the "equal to" result to force the result
980 status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
981 if (status == 0 && id != adap->nr) {
983 idr_remove(&i2c_adapter_idr, id);
985 mutex_unlock(&core_lock);
986 if (status == -EAGAIN)
990 status = i2c_register_adapter(adap);
993 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
995 static int i2c_do_del_adapter(struct i2c_driver *driver,
996 struct i2c_adapter *adapter)
998 struct i2c_client *client, *_n;
1001 /* Remove the devices we created ourselves as the result of hardware
1002 * probing (using a driver's detect method) */
1003 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1004 if (client->adapter == adapter) {
1005 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1006 client->name, client->addr);
1007 list_del(&client->detected);
1008 i2c_unregister_device(client);
1012 if (!driver->detach_adapter)
1014 res = driver->detach_adapter(adapter);
1016 dev_err(&adapter->dev, "detach_adapter failed (%d) "
1017 "for driver [%s]\n", res, driver->driver.name);
1021 static int __unregister_client(struct device *dev, void *dummy)
1023 struct i2c_client *client = i2c_verify_client(dev);
1024 if (client && strcmp(client->name, "dummy"))
1025 i2c_unregister_device(client);
1029 static int __unregister_dummy(struct device *dev, void *dummy)
1031 struct i2c_client *client = i2c_verify_client(dev);
1033 i2c_unregister_device(client);
1037 static int __process_removed_adapter(struct device_driver *d, void *data)
1039 return i2c_do_del_adapter(to_i2c_driver(d), data);
1043 * i2c_del_adapter - unregister I2C adapter
1044 * @adap: the adapter being unregistered
1045 * Context: can sleep
1047 * This unregisters an I2C adapter which was previously registered
1048 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1050 int i2c_del_adapter(struct i2c_adapter *adap)
1053 struct i2c_adapter *found;
1054 struct i2c_client *client, *next;
1056 /* First make sure that this adapter was ever added */
1057 mutex_lock(&core_lock);
1058 found = idr_find(&i2c_adapter_idr, adap->nr);
1059 mutex_unlock(&core_lock);
1060 if (found != adap) {
1061 pr_debug("i2c-core: attempting to delete unregistered "
1062 "adapter [%s]\n", adap->name);
1066 /* Tell drivers about this removal */
1067 mutex_lock(&core_lock);
1068 res = bus_for_each_drv(&i2c_bus_type, NULL, adap,
1069 __process_removed_adapter);
1070 mutex_unlock(&core_lock);
1074 /* Remove devices instantiated from sysfs */
1075 mutex_lock(&adap->userspace_clients_lock);
1076 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1078 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1080 list_del(&client->detected);
1081 i2c_unregister_device(client);
1083 mutex_unlock(&adap->userspace_clients_lock);
1085 /* Detach any active clients. This can't fail, thus we do not
1086 * check the returned value. This is a two-pass process, because
1087 * we can't remove the dummy devices during the first pass: they
1088 * could have been instantiated by real devices wishing to clean
1089 * them up properly, so we give them a chance to do that first. */
1090 res = device_for_each_child(&adap->dev, NULL, __unregister_client);
1091 res = device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1093 #ifdef CONFIG_I2C_COMPAT
1094 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1098 /* device name is gone after device_unregister */
1099 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1101 /* clean up the sysfs representation */
1102 init_completion(&adap->dev_released);
1103 device_unregister(&adap->dev);
1105 /* wait for sysfs to drop all references */
1106 wait_for_completion(&adap->dev_released);
1109 mutex_lock(&core_lock);
1110 idr_remove(&i2c_adapter_idr, adap->nr);
1111 mutex_unlock(&core_lock);
1113 /* Clear the device structure in case this adapter is ever going to be
1115 memset(&adap->dev, 0, sizeof(adap->dev));
1119 EXPORT_SYMBOL(i2c_del_adapter);
1122 /* ------------------------------------------------------------------------- */
1124 static int __process_new_driver(struct device *dev, void *data)
1126 if (dev->type != &i2c_adapter_type)
1128 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1132 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1133 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1136 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1140 /* Can't register until after driver model init */
1141 if (unlikely(WARN_ON(!i2c_bus_type.p)))
1144 /* add the driver to the list of i2c drivers in the driver core */
1145 driver->driver.owner = owner;
1146 driver->driver.bus = &i2c_bus_type;
1148 /* When registration returns, the driver core
1149 * will have called probe() for all matching-but-unbound devices.
1151 res = driver_register(&driver->driver);
1155 pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
1157 INIT_LIST_HEAD(&driver->clients);
1158 /* Walk the adapters that are already present */
1159 mutex_lock(&core_lock);
1160 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_new_driver);
1161 mutex_unlock(&core_lock);
1165 EXPORT_SYMBOL(i2c_register_driver);
1167 static int __process_removed_driver(struct device *dev, void *data)
1169 if (dev->type != &i2c_adapter_type)
1171 return i2c_do_del_adapter(data, to_i2c_adapter(dev));
1175 * i2c_del_driver - unregister I2C driver
1176 * @driver: the driver being unregistered
1177 * Context: can sleep
1179 void i2c_del_driver(struct i2c_driver *driver)
1181 mutex_lock(&core_lock);
1182 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_removed_driver);
1183 mutex_unlock(&core_lock);
1185 driver_unregister(&driver->driver);
1186 pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
1188 EXPORT_SYMBOL(i2c_del_driver);
1190 /* ------------------------------------------------------------------------- */
1193 * i2c_use_client - increments the reference count of the i2c client structure
1194 * @client: the client being referenced
1196 * Each live reference to a client should be refcounted. The driver model does
1197 * that automatically as part of driver binding, so that most drivers don't
1198 * need to do this explicitly: they hold a reference until they're unbound
1201 * A pointer to the client with the incremented reference counter is returned.
1203 struct i2c_client *i2c_use_client(struct i2c_client *client)
1205 if (client && get_device(&client->dev))
1209 EXPORT_SYMBOL(i2c_use_client);
1212 * i2c_release_client - release a use of the i2c client structure
1213 * @client: the client being no longer referenced
1215 * Must be called when a user of a client is finished with it.
1217 void i2c_release_client(struct i2c_client *client)
1220 put_device(&client->dev);
1222 EXPORT_SYMBOL(i2c_release_client);
1224 struct i2c_cmd_arg {
1229 static int i2c_cmd(struct device *dev, void *_arg)
1231 struct i2c_client *client = i2c_verify_client(dev);
1232 struct i2c_cmd_arg *arg = _arg;
1234 if (client && client->driver && client->driver->command)
1235 client->driver->command(client, arg->cmd, arg->arg);
1239 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1241 struct i2c_cmd_arg cmd_arg;
1245 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1247 EXPORT_SYMBOL(i2c_clients_command);
1249 static int __init i2c_init(void)
1253 retval = bus_register(&i2c_bus_type);
1256 #ifdef CONFIG_I2C_COMPAT
1257 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1258 if (!i2c_adapter_compat_class) {
1263 retval = i2c_add_driver(&dummy_driver);
1269 #ifdef CONFIG_I2C_COMPAT
1270 class_compat_unregister(i2c_adapter_compat_class);
1273 bus_unregister(&i2c_bus_type);
1277 static void __exit i2c_exit(void)
1279 i2c_del_driver(&dummy_driver);
1280 #ifdef CONFIG_I2C_COMPAT
1281 class_compat_unregister(i2c_adapter_compat_class);
1283 bus_unregister(&i2c_bus_type);
1286 /* We must initialize early, because some subsystems register i2c drivers
1287 * in subsys_initcall() code, but are linked (and initialized) before i2c.
1289 postcore_initcall(i2c_init);
1290 module_exit(i2c_exit);
1292 /* ----------------------------------------------------
1293 * the functional interface to the i2c busses.
1294 * ----------------------------------------------------
1298 * i2c_transfer - execute a single or combined I2C message
1299 * @adap: Handle to I2C bus
1300 * @msgs: One or more messages to execute before STOP is issued to
1301 * terminate the operation; each message begins with a START.
1302 * @num: Number of messages to be executed.
1304 * Returns negative errno, else the number of messages executed.
1306 * Note that there is no requirement that each message be sent to
1307 * the same slave address, although that is the most common model.
1309 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1311 unsigned long orig_jiffies;
1314 /* REVISIT the fault reporting model here is weak:
1316 * - When we get an error after receiving N bytes from a slave,
1317 * there is no way to report "N".
1319 * - When we get a NAK after transmitting N bytes to a slave,
1320 * there is no way to report "N" ... or to let the master
1321 * continue executing the rest of this combined message, if
1322 * that's the appropriate response.
1324 * - When for example "num" is two and we successfully complete
1325 * the first message but get an error part way through the
1326 * second, it's unclear whether that should be reported as
1327 * one (discarding status on the second message) or errno
1328 * (discarding status on the first one).
1331 if (adap->algo->master_xfer) {
1333 for (ret = 0; ret < num; ret++) {
1334 dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
1335 "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
1336 ? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
1337 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1341 if (in_atomic() || irqs_disabled()) {
1342 ret = i2c_trylock_adapter(adap);
1344 /* I2C activity is ongoing. */
1347 i2c_lock_adapter(adap);
1350 /* Retry automatically on arbitration loss */
1351 orig_jiffies = jiffies;
1352 for (ret = 0, try = 0; try <= adap->retries; try++) {
1353 ret = adap->algo->master_xfer(adap, msgs, num);
1356 if (time_after(jiffies, orig_jiffies + adap->timeout))
1359 i2c_unlock_adapter(adap);
1363 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1367 EXPORT_SYMBOL(i2c_transfer);
1370 * i2c_master_send - issue a single I2C message in master transmit mode
1371 * @client: Handle to slave device
1372 * @buf: Data that will be written to the slave
1373 * @count: How many bytes to write, must be less than 64k since msg.len is u16
1375 * Returns negative errno, or else the number of bytes written.
1377 int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
1380 struct i2c_adapter *adap = client->adapter;
1383 msg.addr = client->addr;
1384 msg.flags = client->flags & I2C_M_TEN;
1386 msg.buf = (char *)buf;
1388 ret = i2c_transfer(adap, &msg, 1);
1390 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1391 transmitted, else error code. */
1392 return (ret == 1) ? count : ret;
1394 EXPORT_SYMBOL(i2c_master_send);
1397 * i2c_master_recv - issue a single I2C message in master receive mode
1398 * @client: Handle to slave device
1399 * @buf: Where to store data read from slave
1400 * @count: How many bytes to read, must be less than 64k since msg.len is u16
1402 * Returns negative errno, or else the number of bytes read.
1404 int i2c_master_recv(const struct i2c_client *client, char *buf, int count)
1406 struct i2c_adapter *adap = client->adapter;
1410 msg.addr = client->addr;
1411 msg.flags = client->flags & I2C_M_TEN;
1412 msg.flags |= I2C_M_RD;
1416 ret = i2c_transfer(adap, &msg, 1);
1418 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1419 transmitted, else error code. */
1420 return (ret == 1) ? count : ret;
1422 EXPORT_SYMBOL(i2c_master_recv);
1424 /* ----------------------------------------------------
1425 * the i2c address scanning function
1426 * Will not work for 10-bit addresses!
1427 * ----------------------------------------------------
1431 * Legacy default probe function, mostly relevant for SMBus. The default
1432 * probe method is a quick write, but it is known to corrupt the 24RF08
1433 * EEPROMs due to a state machine bug, and could also irreversibly
1434 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
1435 * we use a short byte read instead. Also, some bus drivers don't implement
1436 * quick write, so we fallback to a byte read in that case too.
1437 * On x86, there is another special case for FSC hardware monitoring chips,
1438 * which want regular byte reads (address 0x73.) Fortunately, these are the
1439 * only known chips using this I2C address on PC hardware.
1440 * Returns 1 if probe succeeded, 0 if not.
1442 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
1445 union i2c_smbus_data dummy;
1448 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
1449 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
1450 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1451 I2C_SMBUS_BYTE_DATA, &dummy);
1454 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
1455 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
1456 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
1457 I2C_SMBUS_QUICK, NULL);
1458 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
1459 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1460 I2C_SMBUS_BYTE, &dummy);
1462 dev_warn(&adap->dev, "No suitable probing method supported\n");
1469 static int i2c_detect_address(struct i2c_client *temp_client,
1470 struct i2c_driver *driver)
1472 struct i2c_board_info info;
1473 struct i2c_adapter *adapter = temp_client->adapter;
1474 int addr = temp_client->addr;
1477 /* Make sure the address is valid */
1478 err = i2c_check_addr_validity(addr);
1480 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
1485 /* Skip if already in use */
1486 if (i2c_check_addr_busy(adapter, addr))
1489 /* Make sure there is something at this address */
1490 if (!i2c_default_probe(adapter, addr))
1493 /* Finally call the custom detection function */
1494 memset(&info, 0, sizeof(struct i2c_board_info));
1496 err = driver->detect(temp_client, &info);
1498 /* -ENODEV is returned if the detection fails. We catch it
1499 here as this isn't an error. */
1500 return err == -ENODEV ? 0 : err;
1503 /* Consistency check */
1504 if (info.type[0] == '\0') {
1505 dev_err(&adapter->dev, "%s detection function provided "
1506 "no name for 0x%x\n", driver->driver.name,
1509 struct i2c_client *client;
1511 /* Detection succeeded, instantiate the device */
1512 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
1513 info.type, info.addr);
1514 client = i2c_new_device(adapter, &info);
1516 list_add_tail(&client->detected, &driver->clients);
1518 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
1519 info.type, info.addr);
1524 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
1526 const unsigned short *address_list;
1527 struct i2c_client *temp_client;
1529 int adap_id = i2c_adapter_id(adapter);
1531 address_list = driver->address_list;
1532 if (!driver->detect || !address_list)
1535 /* Stop here if the classes do not match */
1536 if (!(adapter->class & driver->class))
1539 /* Set up a temporary client to help detect callback */
1540 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
1543 temp_client->adapter = adapter;
1545 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
1546 dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
1547 "addr 0x%02x\n", adap_id, address_list[i]);
1548 temp_client->addr = address_list[i];
1549 err = i2c_detect_address(temp_client, driver);
1558 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
1560 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1561 I2C_SMBUS_QUICK, NULL) >= 0;
1563 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
1566 i2c_new_probed_device(struct i2c_adapter *adap,
1567 struct i2c_board_info *info,
1568 unsigned short const *addr_list,
1569 int (*probe)(struct i2c_adapter *, unsigned short addr))
1574 probe = i2c_default_probe;
1576 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
1577 /* Check address validity */
1578 if (i2c_check_addr_validity(addr_list[i]) < 0) {
1579 dev_warn(&adap->dev, "Invalid 7-bit address "
1580 "0x%02x\n", addr_list[i]);
1584 /* Check address availability */
1585 if (i2c_check_addr_busy(adap, addr_list[i])) {
1586 dev_dbg(&adap->dev, "Address 0x%02x already in "
1587 "use, not probing\n", addr_list[i]);
1591 /* Test address responsiveness */
1592 if (probe(adap, addr_list[i]))
1596 if (addr_list[i] == I2C_CLIENT_END) {
1597 dev_dbg(&adap->dev, "Probing failed, no device found\n");
1601 info->addr = addr_list[i];
1602 return i2c_new_device(adap, info);
1604 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
1606 struct i2c_adapter *i2c_get_adapter(int id)
1608 struct i2c_adapter *adapter;
1610 mutex_lock(&core_lock);
1611 adapter = idr_find(&i2c_adapter_idr, id);
1612 if (adapter && !try_module_get(adapter->owner))
1615 mutex_unlock(&core_lock);
1618 EXPORT_SYMBOL(i2c_get_adapter);
1620 void i2c_put_adapter(struct i2c_adapter *adap)
1622 module_put(adap->owner);
1624 EXPORT_SYMBOL(i2c_put_adapter);
1626 /* The SMBus parts */
1628 #define POLY (0x1070U << 3)
1629 static u8 crc8(u16 data)
1633 for (i = 0; i < 8; i++) {
1638 return (u8)(data >> 8);
1641 /* Incremental CRC8 over count bytes in the array pointed to by p */
1642 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
1646 for (i = 0; i < count; i++)
1647 crc = crc8((crc ^ p[i]) << 8);
1651 /* Assume a 7-bit address, which is reasonable for SMBus */
1652 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
1654 /* The address will be sent first */
1655 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
1656 pec = i2c_smbus_pec(pec, &addr, 1);
1658 /* The data buffer follows */
1659 return i2c_smbus_pec(pec, msg->buf, msg->len);
1662 /* Used for write only transactions */
1663 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
1665 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
1669 /* Return <0 on CRC error
1670 If there was a write before this read (most cases) we need to take the
1671 partial CRC from the write part into account.
1672 Note that this function does modify the message (we need to decrease the
1673 message length to hide the CRC byte from the caller). */
1674 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
1676 u8 rpec = msg->buf[--msg->len];
1677 cpec = i2c_smbus_msg_pec(cpec, msg);
1680 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
1688 * i2c_smbus_read_byte - SMBus "receive byte" protocol
1689 * @client: Handle to slave device
1691 * This executes the SMBus "receive byte" protocol, returning negative errno
1692 * else the byte received from the device.
1694 s32 i2c_smbus_read_byte(const struct i2c_client *client)
1696 union i2c_smbus_data data;
1699 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1701 I2C_SMBUS_BYTE, &data);
1702 return (status < 0) ? status : data.byte;
1704 EXPORT_SYMBOL(i2c_smbus_read_byte);
1707 * i2c_smbus_write_byte - SMBus "send byte" protocol
1708 * @client: Handle to slave device
1709 * @value: Byte to be sent
1711 * This executes the SMBus "send byte" protocol, returning negative errno
1712 * else zero on success.
1714 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
1716 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1717 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
1719 EXPORT_SYMBOL(i2c_smbus_write_byte);
1722 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
1723 * @client: Handle to slave device
1724 * @command: Byte interpreted by slave
1726 * This executes the SMBus "read byte" protocol, returning negative errno
1727 * else a data byte received from the device.
1729 s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
1731 union i2c_smbus_data data;
1734 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1735 I2C_SMBUS_READ, command,
1736 I2C_SMBUS_BYTE_DATA, &data);
1737 return (status < 0) ? status : data.byte;
1739 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
1742 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
1743 * @client: Handle to slave device
1744 * @command: Byte interpreted by slave
1745 * @value: Byte being written
1747 * This executes the SMBus "write byte" protocol, returning negative errno
1748 * else zero on success.
1750 s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
1753 union i2c_smbus_data data;
1755 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1756 I2C_SMBUS_WRITE, command,
1757 I2C_SMBUS_BYTE_DATA, &data);
1759 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
1762 * i2c_smbus_read_word_data - SMBus "read word" protocol
1763 * @client: Handle to slave device
1764 * @command: Byte interpreted by slave
1766 * This executes the SMBus "read word" protocol, returning negative errno
1767 * else a 16-bit unsigned "word" received from the device.
1769 s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
1771 union i2c_smbus_data data;
1774 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1775 I2C_SMBUS_READ, command,
1776 I2C_SMBUS_WORD_DATA, &data);
1777 return (status < 0) ? status : data.word;
1779 EXPORT_SYMBOL(i2c_smbus_read_word_data);
1782 * i2c_smbus_write_word_data - SMBus "write word" protocol
1783 * @client: Handle to slave device
1784 * @command: Byte interpreted by slave
1785 * @value: 16-bit "word" being written
1787 * This executes the SMBus "write word" protocol, returning negative errno
1788 * else zero on success.
1790 s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
1793 union i2c_smbus_data data;
1795 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1796 I2C_SMBUS_WRITE, command,
1797 I2C_SMBUS_WORD_DATA, &data);
1799 EXPORT_SYMBOL(i2c_smbus_write_word_data);
1802 * i2c_smbus_process_call - SMBus "process call" protocol
1803 * @client: Handle to slave device
1804 * @command: Byte interpreted by slave
1805 * @value: 16-bit "word" being written
1807 * This executes the SMBus "process call" protocol, returning negative errno
1808 * else a 16-bit unsigned "word" received from the device.
1810 s32 i2c_smbus_process_call(const struct i2c_client *client, u8 command,
1813 union i2c_smbus_data data;
1817 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1818 I2C_SMBUS_WRITE, command,
1819 I2C_SMBUS_PROC_CALL, &data);
1820 return (status < 0) ? status : data.word;
1822 EXPORT_SYMBOL(i2c_smbus_process_call);
1825 * i2c_smbus_read_block_data - SMBus "block read" protocol
1826 * @client: Handle to slave device
1827 * @command: Byte interpreted by slave
1828 * @values: Byte array into which data will be read; big enough to hold
1829 * the data returned by the slave. SMBus allows at most 32 bytes.
1831 * This executes the SMBus "block read" protocol, returning negative errno
1832 * else the number of data bytes in the slave's response.
1834 * Note that using this function requires that the client's adapter support
1835 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
1836 * support this; its emulation through I2C messaging relies on a specific
1837 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
1839 s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
1842 union i2c_smbus_data data;
1845 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1846 I2C_SMBUS_READ, command,
1847 I2C_SMBUS_BLOCK_DATA, &data);
1851 memcpy(values, &data.block[1], data.block[0]);
1852 return data.block[0];
1854 EXPORT_SYMBOL(i2c_smbus_read_block_data);
1857 * i2c_smbus_write_block_data - SMBus "block write" protocol
1858 * @client: Handle to slave device
1859 * @command: Byte interpreted by slave
1860 * @length: Size of data block; SMBus allows at most 32 bytes
1861 * @values: Byte array which will be written.
1863 * This executes the SMBus "block write" protocol, returning negative errno
1864 * else zero on success.
1866 s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
1867 u8 length, const u8 *values)
1869 union i2c_smbus_data data;
1871 if (length > I2C_SMBUS_BLOCK_MAX)
1872 length = I2C_SMBUS_BLOCK_MAX;
1873 data.block[0] = length;
1874 memcpy(&data.block[1], values, length);
1875 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1876 I2C_SMBUS_WRITE, command,
1877 I2C_SMBUS_BLOCK_DATA, &data);
1879 EXPORT_SYMBOL(i2c_smbus_write_block_data);
1881 /* Returns the number of read bytes */
1882 s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
1883 u8 length, u8 *values)
1885 union i2c_smbus_data data;
1888 if (length > I2C_SMBUS_BLOCK_MAX)
1889 length = I2C_SMBUS_BLOCK_MAX;
1890 data.block[0] = length;
1891 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1892 I2C_SMBUS_READ, command,
1893 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1897 memcpy(values, &data.block[1], data.block[0]);
1898 return data.block[0];
1900 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
1902 s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
1903 u8 length, const u8 *values)
1905 union i2c_smbus_data data;
1907 if (length > I2C_SMBUS_BLOCK_MAX)
1908 length = I2C_SMBUS_BLOCK_MAX;
1909 data.block[0] = length;
1910 memcpy(data.block + 1, values, length);
1911 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1912 I2C_SMBUS_WRITE, command,
1913 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1915 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
1917 /* Simulate a SMBus command using the i2c protocol
1918 No checking of parameters is done! */
1919 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
1920 unsigned short flags,
1921 char read_write, u8 command, int size,
1922 union i2c_smbus_data *data)
1924 /* So we need to generate a series of msgs. In the case of writing, we
1925 need to use only one message; when reading, we need two. We initialize
1926 most things with sane defaults, to keep the code below somewhat
1928 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
1929 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
1930 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
1931 struct i2c_msg msg[2] = { { addr, flags, 1, msgbuf0 },
1932 { addr, flags | I2C_M_RD, 0, msgbuf1 }
1938 msgbuf0[0] = command;
1940 case I2C_SMBUS_QUICK:
1942 /* Special case: The read/write field is used as data */
1943 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
1947 case I2C_SMBUS_BYTE:
1948 if (read_write == I2C_SMBUS_READ) {
1949 /* Special case: only a read! */
1950 msg[0].flags = I2C_M_RD | flags;
1954 case I2C_SMBUS_BYTE_DATA:
1955 if (read_write == I2C_SMBUS_READ)
1959 msgbuf0[1] = data->byte;
1962 case I2C_SMBUS_WORD_DATA:
1963 if (read_write == I2C_SMBUS_READ)
1967 msgbuf0[1] = data->word & 0xff;
1968 msgbuf0[2] = data->word >> 8;
1971 case I2C_SMBUS_PROC_CALL:
1972 num = 2; /* Special case */
1973 read_write = I2C_SMBUS_READ;
1976 msgbuf0[1] = data->word & 0xff;
1977 msgbuf0[2] = data->word >> 8;
1979 case I2C_SMBUS_BLOCK_DATA:
1980 if (read_write == I2C_SMBUS_READ) {
1981 msg[1].flags |= I2C_M_RECV_LEN;
1982 msg[1].len = 1; /* block length will be added by
1983 the underlying bus driver */
1985 msg[0].len = data->block[0] + 2;
1986 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
1987 dev_err(&adapter->dev,
1988 "Invalid block write size %d\n",
1992 for (i = 1; i < msg[0].len; i++)
1993 msgbuf0[i] = data->block[i-1];
1996 case I2C_SMBUS_BLOCK_PROC_CALL:
1997 num = 2; /* Another special case */
1998 read_write = I2C_SMBUS_READ;
1999 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
2000 dev_err(&adapter->dev,
2001 "Invalid block write size %d\n",
2005 msg[0].len = data->block[0] + 2;
2006 for (i = 1; i < msg[0].len; i++)
2007 msgbuf0[i] = data->block[i-1];
2008 msg[1].flags |= I2C_M_RECV_LEN;
2009 msg[1].len = 1; /* block length will be added by
2010 the underlying bus driver */
2012 case I2C_SMBUS_I2C_BLOCK_DATA:
2013 if (read_write == I2C_SMBUS_READ) {
2014 msg[1].len = data->block[0];
2016 msg[0].len = data->block[0] + 1;
2017 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
2018 dev_err(&adapter->dev,
2019 "Invalid block write size %d\n",
2023 for (i = 1; i <= data->block[0]; i++)
2024 msgbuf0[i] = data->block[i];
2028 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
2032 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
2033 && size != I2C_SMBUS_I2C_BLOCK_DATA);
2035 /* Compute PEC if first message is a write */
2036 if (!(msg[0].flags & I2C_M_RD)) {
2037 if (num == 1) /* Write only */
2038 i2c_smbus_add_pec(&msg[0]);
2039 else /* Write followed by read */
2040 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
2042 /* Ask for PEC if last message is a read */
2043 if (msg[num-1].flags & I2C_M_RD)
2047 status = i2c_transfer(adapter, msg, num);
2051 /* Check PEC if last message is a read */
2052 if (i && (msg[num-1].flags & I2C_M_RD)) {
2053 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
2058 if (read_write == I2C_SMBUS_READ)
2060 case I2C_SMBUS_BYTE:
2061 data->byte = msgbuf0[0];
2063 case I2C_SMBUS_BYTE_DATA:
2064 data->byte = msgbuf1[0];
2066 case I2C_SMBUS_WORD_DATA:
2067 case I2C_SMBUS_PROC_CALL:
2068 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
2070 case I2C_SMBUS_I2C_BLOCK_DATA:
2071 for (i = 0; i < data->block[0]; i++)
2072 data->block[i+1] = msgbuf1[i];
2074 case I2C_SMBUS_BLOCK_DATA:
2075 case I2C_SMBUS_BLOCK_PROC_CALL:
2076 for (i = 0; i < msgbuf1[0] + 1; i++)
2077 data->block[i] = msgbuf1[i];
2084 * i2c_smbus_xfer - execute SMBus protocol operations
2085 * @adapter: Handle to I2C bus
2086 * @addr: Address of SMBus slave on that bus
2087 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
2088 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
2089 * @command: Byte interpreted by slave, for protocols which use such bytes
2090 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
2091 * @data: Data to be read or written
2093 * This executes an SMBus protocol operation, and returns a negative
2094 * errno code else zero on success.
2096 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
2097 char read_write, u8 command, int protocol,
2098 union i2c_smbus_data *data)
2100 unsigned long orig_jiffies;
2104 flags &= I2C_M_TEN | I2C_CLIENT_PEC;
2106 if (adapter->algo->smbus_xfer) {
2107 i2c_lock_adapter(adapter);
2109 /* Retry automatically on arbitration loss */
2110 orig_jiffies = jiffies;
2111 for (res = 0, try = 0; try <= adapter->retries; try++) {
2112 res = adapter->algo->smbus_xfer(adapter, addr, flags,
2113 read_write, command,
2117 if (time_after(jiffies,
2118 orig_jiffies + adapter->timeout))
2121 i2c_unlock_adapter(adapter);
2123 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
2124 command, protocol, data);
2128 EXPORT_SYMBOL(i2c_smbus_xfer);
2130 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2131 MODULE_DESCRIPTION("I2C-Bus main module");
2132 MODULE_LICENSE("GPL");