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))) {
851 rt_mutex_init(&adap->bus_lock);
852 mutex_init(&adap->userspace_clients_lock);
853 INIT_LIST_HEAD(&adap->userspace_clients);
855 /* Set default timeout to 1 second if not already set */
856 if (adap->timeout == 0)
859 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
860 adap->dev.bus = &i2c_bus_type;
861 adap->dev.type = &i2c_adapter_type;
862 res = device_register(&adap->dev);
866 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
868 #ifdef CONFIG_I2C_COMPAT
869 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
873 "Failed to create compatibility class link\n");
876 /* create pre-declared device nodes */
877 if (adap->nr < __i2c_first_dynamic_bus_num)
878 i2c_scan_static_board_info(adap);
881 mutex_lock(&core_lock);
882 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
883 mutex_unlock(&core_lock);
888 mutex_lock(&core_lock);
889 idr_remove(&i2c_adapter_idr, adap->nr);
890 mutex_unlock(&core_lock);
895 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
896 * @adapter: the adapter to add
899 * This routine is used to declare an I2C adapter when its bus number
900 * doesn't matter. Examples: for I2C adapters dynamically added by
901 * USB links or PCI plugin cards.
903 * When this returns zero, a new bus number was allocated and stored
904 * in adap->nr, and the specified adapter became available for clients.
905 * Otherwise, a negative errno value is returned.
907 int i2c_add_adapter(struct i2c_adapter *adapter)
912 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
915 mutex_lock(&core_lock);
916 /* "above" here means "above or equal to", sigh */
917 res = idr_get_new_above(&i2c_adapter_idr, adapter,
918 __i2c_first_dynamic_bus_num, &id);
919 mutex_unlock(&core_lock);
928 return i2c_register_adapter(adapter);
930 EXPORT_SYMBOL(i2c_add_adapter);
933 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
934 * @adap: the adapter to register (with adap->nr initialized)
937 * This routine is used to declare an I2C adapter when its bus number
938 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
939 * or otherwise built in to the system's mainboard, and where i2c_board_info
940 * is used to properly configure I2C devices.
942 * If no devices have pre-been declared for this bus, then be sure to
943 * register the adapter before any dynamically allocated ones. Otherwise
944 * the required bus ID may not be available.
946 * When this returns zero, the specified adapter became available for
947 * clients using the bus number provided in adap->nr. Also, the table
948 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
949 * and the appropriate driver model device nodes are created. Otherwise, a
950 * negative errno value is returned.
952 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
957 if (adap->nr & ~MAX_ID_MASK)
961 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
964 mutex_lock(&core_lock);
965 /* "above" here means "above or equal to", sigh;
966 * we need the "equal to" result to force the result
968 status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
969 if (status == 0 && id != adap->nr) {
971 idr_remove(&i2c_adapter_idr, id);
973 mutex_unlock(&core_lock);
974 if (status == -EAGAIN)
978 status = i2c_register_adapter(adap);
981 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
983 static int i2c_do_del_adapter(struct i2c_driver *driver,
984 struct i2c_adapter *adapter)
986 struct i2c_client *client, *_n;
989 /* Remove the devices we created ourselves as the result of hardware
990 * probing (using a driver's detect method) */
991 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
992 if (client->adapter == adapter) {
993 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
994 client->name, client->addr);
995 list_del(&client->detected);
996 i2c_unregister_device(client);
1000 if (!driver->detach_adapter)
1002 res = driver->detach_adapter(adapter);
1004 dev_err(&adapter->dev, "detach_adapter failed (%d) "
1005 "for driver [%s]\n", res, driver->driver.name);
1009 static int __unregister_client(struct device *dev, void *dummy)
1011 struct i2c_client *client = i2c_verify_client(dev);
1013 i2c_unregister_device(client);
1017 static int __process_removed_adapter(struct device_driver *d, void *data)
1019 return i2c_do_del_adapter(to_i2c_driver(d), data);
1023 * i2c_del_adapter - unregister I2C adapter
1024 * @adap: the adapter being unregistered
1025 * Context: can sleep
1027 * This unregisters an I2C adapter which was previously registered
1028 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1030 int i2c_del_adapter(struct i2c_adapter *adap)
1033 struct i2c_adapter *found;
1034 struct i2c_client *client, *next;
1036 /* First make sure that this adapter was ever added */
1037 mutex_lock(&core_lock);
1038 found = idr_find(&i2c_adapter_idr, adap->nr);
1039 mutex_unlock(&core_lock);
1040 if (found != adap) {
1041 pr_debug("i2c-core: attempting to delete unregistered "
1042 "adapter [%s]\n", adap->name);
1046 /* Tell drivers about this removal */
1047 mutex_lock(&core_lock);
1048 res = bus_for_each_drv(&i2c_bus_type, NULL, adap,
1049 __process_removed_adapter);
1050 mutex_unlock(&core_lock);
1054 /* Remove devices instantiated from sysfs */
1055 mutex_lock(&adap->userspace_clients_lock);
1056 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1058 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1060 list_del(&client->detected);
1061 i2c_unregister_device(client);
1063 mutex_unlock(&adap->userspace_clients_lock);
1065 /* Detach any active clients. This can't fail, thus we do not
1066 checking the returned value. */
1067 res = device_for_each_child(&adap->dev, NULL, __unregister_client);
1069 #ifdef CONFIG_I2C_COMPAT
1070 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1074 /* device name is gone after device_unregister */
1075 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1077 /* clean up the sysfs representation */
1078 init_completion(&adap->dev_released);
1079 device_unregister(&adap->dev);
1081 /* wait for sysfs to drop all references */
1082 wait_for_completion(&adap->dev_released);
1085 mutex_lock(&core_lock);
1086 idr_remove(&i2c_adapter_idr, adap->nr);
1087 mutex_unlock(&core_lock);
1089 /* Clear the device structure in case this adapter is ever going to be
1091 memset(&adap->dev, 0, sizeof(adap->dev));
1095 EXPORT_SYMBOL(i2c_del_adapter);
1098 /* ------------------------------------------------------------------------- */
1100 static int __process_new_driver(struct device *dev, void *data)
1102 if (dev->type != &i2c_adapter_type)
1104 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1108 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1109 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1112 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1116 /* Can't register until after driver model init */
1117 if (unlikely(WARN_ON(!i2c_bus_type.p)))
1120 /* add the driver to the list of i2c drivers in the driver core */
1121 driver->driver.owner = owner;
1122 driver->driver.bus = &i2c_bus_type;
1124 /* When registration returns, the driver core
1125 * will have called probe() for all matching-but-unbound devices.
1127 res = driver_register(&driver->driver);
1131 pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
1133 INIT_LIST_HEAD(&driver->clients);
1134 /* Walk the adapters that are already present */
1135 mutex_lock(&core_lock);
1136 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_new_driver);
1137 mutex_unlock(&core_lock);
1141 EXPORT_SYMBOL(i2c_register_driver);
1143 static int __process_removed_driver(struct device *dev, void *data)
1145 if (dev->type != &i2c_adapter_type)
1147 return i2c_do_del_adapter(data, to_i2c_adapter(dev));
1151 * i2c_del_driver - unregister I2C driver
1152 * @driver: the driver being unregistered
1153 * Context: can sleep
1155 void i2c_del_driver(struct i2c_driver *driver)
1157 mutex_lock(&core_lock);
1158 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_removed_driver);
1159 mutex_unlock(&core_lock);
1161 driver_unregister(&driver->driver);
1162 pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
1164 EXPORT_SYMBOL(i2c_del_driver);
1166 /* ------------------------------------------------------------------------- */
1169 * i2c_use_client - increments the reference count of the i2c client structure
1170 * @client: the client being referenced
1172 * Each live reference to a client should be refcounted. The driver model does
1173 * that automatically as part of driver binding, so that most drivers don't
1174 * need to do this explicitly: they hold a reference until they're unbound
1177 * A pointer to the client with the incremented reference counter is returned.
1179 struct i2c_client *i2c_use_client(struct i2c_client *client)
1181 if (client && get_device(&client->dev))
1185 EXPORT_SYMBOL(i2c_use_client);
1188 * i2c_release_client - release a use of the i2c client structure
1189 * @client: the client being no longer referenced
1191 * Must be called when a user of a client is finished with it.
1193 void i2c_release_client(struct i2c_client *client)
1196 put_device(&client->dev);
1198 EXPORT_SYMBOL(i2c_release_client);
1200 struct i2c_cmd_arg {
1205 static int i2c_cmd(struct device *dev, void *_arg)
1207 struct i2c_client *client = i2c_verify_client(dev);
1208 struct i2c_cmd_arg *arg = _arg;
1210 if (client && client->driver && client->driver->command)
1211 client->driver->command(client, arg->cmd, arg->arg);
1215 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1217 struct i2c_cmd_arg cmd_arg;
1221 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1223 EXPORT_SYMBOL(i2c_clients_command);
1225 static int __init i2c_init(void)
1229 retval = bus_register(&i2c_bus_type);
1232 #ifdef CONFIG_I2C_COMPAT
1233 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1234 if (!i2c_adapter_compat_class) {
1239 retval = i2c_add_driver(&dummy_driver);
1245 #ifdef CONFIG_I2C_COMPAT
1246 class_compat_unregister(i2c_adapter_compat_class);
1249 bus_unregister(&i2c_bus_type);
1253 static void __exit i2c_exit(void)
1255 i2c_del_driver(&dummy_driver);
1256 #ifdef CONFIG_I2C_COMPAT
1257 class_compat_unregister(i2c_adapter_compat_class);
1259 bus_unregister(&i2c_bus_type);
1262 /* We must initialize early, because some subsystems register i2c drivers
1263 * in subsys_initcall() code, but are linked (and initialized) before i2c.
1265 postcore_initcall(i2c_init);
1266 module_exit(i2c_exit);
1268 /* ----------------------------------------------------
1269 * the functional interface to the i2c busses.
1270 * ----------------------------------------------------
1274 * i2c_transfer - execute a single or combined I2C message
1275 * @adap: Handle to I2C bus
1276 * @msgs: One or more messages to execute before STOP is issued to
1277 * terminate the operation; each message begins with a START.
1278 * @num: Number of messages to be executed.
1280 * Returns negative errno, else the number of messages executed.
1282 * Note that there is no requirement that each message be sent to
1283 * the same slave address, although that is the most common model.
1285 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1287 unsigned long orig_jiffies;
1290 /* REVISIT the fault reporting model here is weak:
1292 * - When we get an error after receiving N bytes from a slave,
1293 * there is no way to report "N".
1295 * - When we get a NAK after transmitting N bytes to a slave,
1296 * there is no way to report "N" ... or to let the master
1297 * continue executing the rest of this combined message, if
1298 * that's the appropriate response.
1300 * - When for example "num" is two and we successfully complete
1301 * the first message but get an error part way through the
1302 * second, it's unclear whether that should be reported as
1303 * one (discarding status on the second message) or errno
1304 * (discarding status on the first one).
1307 if (adap->algo->master_xfer) {
1309 for (ret = 0; ret < num; ret++) {
1310 dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
1311 "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
1312 ? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
1313 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1317 if (in_atomic() || irqs_disabled()) {
1318 ret = i2c_trylock_adapter(adap);
1320 /* I2C activity is ongoing. */
1323 i2c_lock_adapter(adap);
1326 /* Retry automatically on arbitration loss */
1327 orig_jiffies = jiffies;
1328 for (ret = 0, try = 0; try <= adap->retries; try++) {
1329 ret = adap->algo->master_xfer(adap, msgs, num);
1332 if (time_after(jiffies, orig_jiffies + adap->timeout))
1335 i2c_unlock_adapter(adap);
1339 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1343 EXPORT_SYMBOL(i2c_transfer);
1346 * i2c_master_send - issue a single I2C message in master transmit mode
1347 * @client: Handle to slave device
1348 * @buf: Data that will be written to the slave
1349 * @count: How many bytes to write, must be less than 64k since msg.len is u16
1351 * Returns negative errno, or else the number of bytes written.
1353 int i2c_master_send(struct i2c_client *client, const char *buf, int count)
1356 struct i2c_adapter *adap = client->adapter;
1359 msg.addr = client->addr;
1360 msg.flags = client->flags & I2C_M_TEN;
1362 msg.buf = (char *)buf;
1364 ret = i2c_transfer(adap, &msg, 1);
1366 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1367 transmitted, else error code. */
1368 return (ret == 1) ? count : ret;
1370 EXPORT_SYMBOL(i2c_master_send);
1373 * i2c_master_recv - issue a single I2C message in master receive mode
1374 * @client: Handle to slave device
1375 * @buf: Where to store data read from slave
1376 * @count: How many bytes to read, must be less than 64k since msg.len is u16
1378 * Returns negative errno, or else the number of bytes read.
1380 int i2c_master_recv(struct i2c_client *client, char *buf, int count)
1382 struct i2c_adapter *adap = client->adapter;
1386 msg.addr = client->addr;
1387 msg.flags = client->flags & I2C_M_TEN;
1388 msg.flags |= I2C_M_RD;
1392 ret = i2c_transfer(adap, &msg, 1);
1394 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1395 transmitted, else error code. */
1396 return (ret == 1) ? count : ret;
1398 EXPORT_SYMBOL(i2c_master_recv);
1400 /* ----------------------------------------------------
1401 * the i2c address scanning function
1402 * Will not work for 10-bit addresses!
1403 * ----------------------------------------------------
1407 * Legacy default probe function, mostly relevant for SMBus. The default
1408 * probe method is a quick write, but it is known to corrupt the 24RF08
1409 * EEPROMs due to a state machine bug, and could also irreversibly
1410 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
1411 * we use a short byte read instead. Also, some bus drivers don't implement
1412 * quick write, so we fallback to a byte read in that case too.
1413 * On x86, there is another special case for FSC hardware monitoring chips,
1414 * which want regular byte reads (address 0x73.) Fortunately, these are the
1415 * only known chips using this I2C address on PC hardware.
1416 * Returns 1 if probe succeeded, 0 if not.
1418 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
1421 union i2c_smbus_data dummy;
1424 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
1425 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
1426 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1427 I2C_SMBUS_BYTE_DATA, &dummy);
1430 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
1431 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
1432 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
1433 I2C_SMBUS_QUICK, NULL);
1434 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
1435 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1436 I2C_SMBUS_BYTE, &dummy);
1438 dev_warn(&adap->dev, "No suitable probing method supported\n");
1445 static int i2c_detect_address(struct i2c_client *temp_client,
1446 struct i2c_driver *driver)
1448 struct i2c_board_info info;
1449 struct i2c_adapter *adapter = temp_client->adapter;
1450 int addr = temp_client->addr;
1453 /* Make sure the address is valid */
1454 err = i2c_check_addr_validity(addr);
1456 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
1461 /* Skip if already in use */
1462 if (i2c_check_addr_busy(adapter, addr))
1465 /* Make sure there is something at this address */
1466 if (!i2c_default_probe(adapter, addr))
1469 /* Finally call the custom detection function */
1470 memset(&info, 0, sizeof(struct i2c_board_info));
1472 err = driver->detect(temp_client, &info);
1474 /* -ENODEV is returned if the detection fails. We catch it
1475 here as this isn't an error. */
1476 return err == -ENODEV ? 0 : err;
1479 /* Consistency check */
1480 if (info.type[0] == '\0') {
1481 dev_err(&adapter->dev, "%s detection function provided "
1482 "no name for 0x%x\n", driver->driver.name,
1485 struct i2c_client *client;
1487 /* Detection succeeded, instantiate the device */
1488 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
1489 info.type, info.addr);
1490 client = i2c_new_device(adapter, &info);
1492 list_add_tail(&client->detected, &driver->clients);
1494 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
1495 info.type, info.addr);
1500 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
1502 const unsigned short *address_list;
1503 struct i2c_client *temp_client;
1505 int adap_id = i2c_adapter_id(adapter);
1507 address_list = driver->address_list;
1508 if (!driver->detect || !address_list)
1511 /* Set up a temporary client to help detect callback */
1512 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
1515 temp_client->adapter = adapter;
1517 /* Stop here if the classes do not match */
1518 if (!(adapter->class & driver->class))
1521 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
1522 dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
1523 "addr 0x%02x\n", adap_id, address_list[i]);
1524 temp_client->addr = address_list[i];
1525 err = i2c_detect_address(temp_client, driver);
1535 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
1537 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1538 I2C_SMBUS_QUICK, NULL) >= 0;
1540 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
1543 i2c_new_probed_device(struct i2c_adapter *adap,
1544 struct i2c_board_info *info,
1545 unsigned short const *addr_list,
1546 int (*probe)(struct i2c_adapter *, unsigned short addr))
1551 probe = i2c_default_probe;
1553 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
1554 /* Check address validity */
1555 if (i2c_check_addr_validity(addr_list[i]) < 0) {
1556 dev_warn(&adap->dev, "Invalid 7-bit address "
1557 "0x%02x\n", addr_list[i]);
1561 /* Check address availability */
1562 if (i2c_check_addr_busy(adap, addr_list[i])) {
1563 dev_dbg(&adap->dev, "Address 0x%02x already in "
1564 "use, not probing\n", addr_list[i]);
1568 /* Test address responsiveness */
1569 if (probe(adap, addr_list[i]))
1573 if (addr_list[i] == I2C_CLIENT_END) {
1574 dev_dbg(&adap->dev, "Probing failed, no device found\n");
1578 info->addr = addr_list[i];
1579 return i2c_new_device(adap, info);
1581 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
1583 struct i2c_adapter *i2c_get_adapter(int id)
1585 struct i2c_adapter *adapter;
1587 mutex_lock(&core_lock);
1588 adapter = idr_find(&i2c_adapter_idr, id);
1589 if (adapter && !try_module_get(adapter->owner))
1592 mutex_unlock(&core_lock);
1595 EXPORT_SYMBOL(i2c_get_adapter);
1597 void i2c_put_adapter(struct i2c_adapter *adap)
1599 module_put(adap->owner);
1601 EXPORT_SYMBOL(i2c_put_adapter);
1603 /* The SMBus parts */
1605 #define POLY (0x1070U << 3)
1606 static u8 crc8(u16 data)
1610 for (i = 0; i < 8; i++) {
1615 return (u8)(data >> 8);
1618 /* Incremental CRC8 over count bytes in the array pointed to by p */
1619 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
1623 for (i = 0; i < count; i++)
1624 crc = crc8((crc ^ p[i]) << 8);
1628 /* Assume a 7-bit address, which is reasonable for SMBus */
1629 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
1631 /* The address will be sent first */
1632 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
1633 pec = i2c_smbus_pec(pec, &addr, 1);
1635 /* The data buffer follows */
1636 return i2c_smbus_pec(pec, msg->buf, msg->len);
1639 /* Used for write only transactions */
1640 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
1642 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
1646 /* Return <0 on CRC error
1647 If there was a write before this read (most cases) we need to take the
1648 partial CRC from the write part into account.
1649 Note that this function does modify the message (we need to decrease the
1650 message length to hide the CRC byte from the caller). */
1651 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
1653 u8 rpec = msg->buf[--msg->len];
1654 cpec = i2c_smbus_msg_pec(cpec, msg);
1657 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
1665 * i2c_smbus_read_byte - SMBus "receive byte" protocol
1666 * @client: Handle to slave device
1668 * This executes the SMBus "receive byte" protocol, returning negative errno
1669 * else the byte received from the device.
1671 s32 i2c_smbus_read_byte(struct i2c_client *client)
1673 union i2c_smbus_data data;
1676 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1678 I2C_SMBUS_BYTE, &data);
1679 return (status < 0) ? status : data.byte;
1681 EXPORT_SYMBOL(i2c_smbus_read_byte);
1684 * i2c_smbus_write_byte - SMBus "send byte" protocol
1685 * @client: Handle to slave device
1686 * @value: Byte to be sent
1688 * This executes the SMBus "send byte" protocol, returning negative errno
1689 * else zero on success.
1691 s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value)
1693 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1694 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
1696 EXPORT_SYMBOL(i2c_smbus_write_byte);
1699 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
1700 * @client: Handle to slave device
1701 * @command: Byte interpreted by slave
1703 * This executes the SMBus "read byte" protocol, returning negative errno
1704 * else a data byte received from the device.
1706 s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
1708 union i2c_smbus_data data;
1711 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1712 I2C_SMBUS_READ, command,
1713 I2C_SMBUS_BYTE_DATA, &data);
1714 return (status < 0) ? status : data.byte;
1716 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
1719 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
1720 * @client: Handle to slave device
1721 * @command: Byte interpreted by slave
1722 * @value: Byte being written
1724 * This executes the SMBus "write byte" protocol, returning negative errno
1725 * else zero on success.
1727 s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value)
1729 union i2c_smbus_data data;
1731 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1732 I2C_SMBUS_WRITE, command,
1733 I2C_SMBUS_BYTE_DATA, &data);
1735 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
1738 * i2c_smbus_read_word_data - SMBus "read word" protocol
1739 * @client: Handle to slave device
1740 * @command: Byte interpreted by slave
1742 * This executes the SMBus "read word" protocol, returning negative errno
1743 * else a 16-bit unsigned "word" received from the device.
1745 s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
1747 union i2c_smbus_data data;
1750 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1751 I2C_SMBUS_READ, command,
1752 I2C_SMBUS_WORD_DATA, &data);
1753 return (status < 0) ? status : data.word;
1755 EXPORT_SYMBOL(i2c_smbus_read_word_data);
1758 * i2c_smbus_write_word_data - SMBus "write word" protocol
1759 * @client: Handle to slave device
1760 * @command: Byte interpreted by slave
1761 * @value: 16-bit "word" being written
1763 * This executes the SMBus "write word" protocol, returning negative errno
1764 * else zero on success.
1766 s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
1768 union i2c_smbus_data data;
1770 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1771 I2C_SMBUS_WRITE, command,
1772 I2C_SMBUS_WORD_DATA, &data);
1774 EXPORT_SYMBOL(i2c_smbus_write_word_data);
1777 * i2c_smbus_process_call - SMBus "process call" protocol
1778 * @client: Handle to slave device
1779 * @command: Byte interpreted by slave
1780 * @value: 16-bit "word" being written
1782 * This executes the SMBus "process call" protocol, returning negative errno
1783 * else a 16-bit unsigned "word" received from the device.
1785 s32 i2c_smbus_process_call(struct i2c_client *client, u8 command, u16 value)
1787 union i2c_smbus_data data;
1791 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1792 I2C_SMBUS_WRITE, command,
1793 I2C_SMBUS_PROC_CALL, &data);
1794 return (status < 0) ? status : data.word;
1796 EXPORT_SYMBOL(i2c_smbus_process_call);
1799 * i2c_smbus_read_block_data - SMBus "block read" protocol
1800 * @client: Handle to slave device
1801 * @command: Byte interpreted by slave
1802 * @values: Byte array into which data will be read; big enough to hold
1803 * the data returned by the slave. SMBus allows at most 32 bytes.
1805 * This executes the SMBus "block read" protocol, returning negative errno
1806 * else the number of data bytes in the slave's response.
1808 * Note that using this function requires that the client's adapter support
1809 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
1810 * support this; its emulation through I2C messaging relies on a specific
1811 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
1813 s32 i2c_smbus_read_block_data(struct i2c_client *client, u8 command,
1816 union i2c_smbus_data data;
1819 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1820 I2C_SMBUS_READ, command,
1821 I2C_SMBUS_BLOCK_DATA, &data);
1825 memcpy(values, &data.block[1], data.block[0]);
1826 return data.block[0];
1828 EXPORT_SYMBOL(i2c_smbus_read_block_data);
1831 * i2c_smbus_write_block_data - SMBus "block write" protocol
1832 * @client: Handle to slave device
1833 * @command: Byte interpreted by slave
1834 * @length: Size of data block; SMBus allows at most 32 bytes
1835 * @values: Byte array which will be written.
1837 * This executes the SMBus "block write" protocol, returning negative errno
1838 * else zero on success.
1840 s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
1841 u8 length, const u8 *values)
1843 union i2c_smbus_data data;
1845 if (length > I2C_SMBUS_BLOCK_MAX)
1846 length = I2C_SMBUS_BLOCK_MAX;
1847 data.block[0] = length;
1848 memcpy(&data.block[1], values, length);
1849 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1850 I2C_SMBUS_WRITE, command,
1851 I2C_SMBUS_BLOCK_DATA, &data);
1853 EXPORT_SYMBOL(i2c_smbus_write_block_data);
1855 /* Returns the number of read bytes */
1856 s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
1857 u8 length, u8 *values)
1859 union i2c_smbus_data data;
1862 if (length > I2C_SMBUS_BLOCK_MAX)
1863 length = I2C_SMBUS_BLOCK_MAX;
1864 data.block[0] = length;
1865 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1866 I2C_SMBUS_READ, command,
1867 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1871 memcpy(values, &data.block[1], data.block[0]);
1872 return data.block[0];
1874 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
1876 s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command,
1877 u8 length, const u8 *values)
1879 union i2c_smbus_data data;
1881 if (length > I2C_SMBUS_BLOCK_MAX)
1882 length = I2C_SMBUS_BLOCK_MAX;
1883 data.block[0] = length;
1884 memcpy(data.block + 1, values, length);
1885 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1886 I2C_SMBUS_WRITE, command,
1887 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1889 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
1891 /* Simulate a SMBus command using the i2c protocol
1892 No checking of parameters is done! */
1893 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
1894 unsigned short flags,
1895 char read_write, u8 command, int size,
1896 union i2c_smbus_data *data)
1898 /* So we need to generate a series of msgs. In the case of writing, we
1899 need to use only one message; when reading, we need two. We initialize
1900 most things with sane defaults, to keep the code below somewhat
1902 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
1903 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
1904 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
1905 struct i2c_msg msg[2] = { { addr, flags, 1, msgbuf0 },
1906 { addr, flags | I2C_M_RD, 0, msgbuf1 }
1912 msgbuf0[0] = command;
1914 case I2C_SMBUS_QUICK:
1916 /* Special case: The read/write field is used as data */
1917 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
1921 case I2C_SMBUS_BYTE:
1922 if (read_write == I2C_SMBUS_READ) {
1923 /* Special case: only a read! */
1924 msg[0].flags = I2C_M_RD | flags;
1928 case I2C_SMBUS_BYTE_DATA:
1929 if (read_write == I2C_SMBUS_READ)
1933 msgbuf0[1] = data->byte;
1936 case I2C_SMBUS_WORD_DATA:
1937 if (read_write == I2C_SMBUS_READ)
1941 msgbuf0[1] = data->word & 0xff;
1942 msgbuf0[2] = data->word >> 8;
1945 case I2C_SMBUS_PROC_CALL:
1946 num = 2; /* Special case */
1947 read_write = I2C_SMBUS_READ;
1950 msgbuf0[1] = data->word & 0xff;
1951 msgbuf0[2] = data->word >> 8;
1953 case I2C_SMBUS_BLOCK_DATA:
1954 if (read_write == I2C_SMBUS_READ) {
1955 msg[1].flags |= I2C_M_RECV_LEN;
1956 msg[1].len = 1; /* block length will be added by
1957 the underlying bus driver */
1959 msg[0].len = data->block[0] + 2;
1960 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
1961 dev_err(&adapter->dev,
1962 "Invalid block write size %d\n",
1966 for (i = 1; i < msg[0].len; i++)
1967 msgbuf0[i] = data->block[i-1];
1970 case I2C_SMBUS_BLOCK_PROC_CALL:
1971 num = 2; /* Another special case */
1972 read_write = I2C_SMBUS_READ;
1973 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
1974 dev_err(&adapter->dev,
1975 "Invalid block write size %d\n",
1979 msg[0].len = data->block[0] + 2;
1980 for (i = 1; i < msg[0].len; i++)
1981 msgbuf0[i] = data->block[i-1];
1982 msg[1].flags |= I2C_M_RECV_LEN;
1983 msg[1].len = 1; /* block length will be added by
1984 the underlying bus driver */
1986 case I2C_SMBUS_I2C_BLOCK_DATA:
1987 if (read_write == I2C_SMBUS_READ) {
1988 msg[1].len = data->block[0];
1990 msg[0].len = data->block[0] + 1;
1991 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
1992 dev_err(&adapter->dev,
1993 "Invalid block write size %d\n",
1997 for (i = 1; i <= data->block[0]; i++)
1998 msgbuf0[i] = data->block[i];
2002 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
2006 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
2007 && size != I2C_SMBUS_I2C_BLOCK_DATA);
2009 /* Compute PEC if first message is a write */
2010 if (!(msg[0].flags & I2C_M_RD)) {
2011 if (num == 1) /* Write only */
2012 i2c_smbus_add_pec(&msg[0]);
2013 else /* Write followed by read */
2014 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
2016 /* Ask for PEC if last message is a read */
2017 if (msg[num-1].flags & I2C_M_RD)
2021 status = i2c_transfer(adapter, msg, num);
2025 /* Check PEC if last message is a read */
2026 if (i && (msg[num-1].flags & I2C_M_RD)) {
2027 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
2032 if (read_write == I2C_SMBUS_READ)
2034 case I2C_SMBUS_BYTE:
2035 data->byte = msgbuf0[0];
2037 case I2C_SMBUS_BYTE_DATA:
2038 data->byte = msgbuf1[0];
2040 case I2C_SMBUS_WORD_DATA:
2041 case I2C_SMBUS_PROC_CALL:
2042 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
2044 case I2C_SMBUS_I2C_BLOCK_DATA:
2045 for (i = 0; i < data->block[0]; i++)
2046 data->block[i+1] = msgbuf1[i];
2048 case I2C_SMBUS_BLOCK_DATA:
2049 case I2C_SMBUS_BLOCK_PROC_CALL:
2050 for (i = 0; i < msgbuf1[0] + 1; i++)
2051 data->block[i] = msgbuf1[i];
2058 * i2c_smbus_xfer - execute SMBus protocol operations
2059 * @adapter: Handle to I2C bus
2060 * @addr: Address of SMBus slave on that bus
2061 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
2062 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
2063 * @command: Byte interpreted by slave, for protocols which use such bytes
2064 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
2065 * @data: Data to be read or written
2067 * This executes an SMBus protocol operation, and returns a negative
2068 * errno code else zero on success.
2070 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
2071 char read_write, u8 command, int protocol,
2072 union i2c_smbus_data *data)
2074 unsigned long orig_jiffies;
2078 flags &= I2C_M_TEN | I2C_CLIENT_PEC;
2080 if (adapter->algo->smbus_xfer) {
2081 i2c_lock_adapter(adapter);
2083 /* Retry automatically on arbitration loss */
2084 orig_jiffies = jiffies;
2085 for (res = 0, try = 0; try <= adapter->retries; try++) {
2086 res = adapter->algo->smbus_xfer(adapter, addr, flags,
2087 read_write, command,
2091 if (time_after(jiffies,
2092 orig_jiffies + adapter->timeout))
2095 i2c_unlock_adapter(adapter);
2097 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
2098 command, protocol, data);
2102 EXPORT_SYMBOL(i2c_smbus_xfer);
2104 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2105 MODULE_DESCRIPTION("I2C-Bus main module");
2106 MODULE_LICENSE("GPL");