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)
430 result = device_for_each_child(&adapter->dev, &addr,
431 __i2c_check_addr_busy);
433 if (!result && i2c_parent_is_i2c_adapter(adapter))
434 result = i2c_check_mux_parents(
435 to_i2c_adapter(adapter->dev.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)
458 if (i2c_parent_is_i2c_adapter(adapter))
459 result = i2c_check_mux_parents(
460 to_i2c_adapter(adapter->dev.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 if (i2c_parent_is_i2c_adapter(adapter))
476 i2c_lock_adapter(to_i2c_adapter(adapter->dev.parent));
478 rt_mutex_lock(&adapter->bus_lock);
480 EXPORT_SYMBOL_GPL(i2c_lock_adapter);
483 * i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment
484 * @adapter: Target I2C bus segment
486 static int i2c_trylock_adapter(struct i2c_adapter *adapter)
488 if (i2c_parent_is_i2c_adapter(adapter))
489 return i2c_trylock_adapter(to_i2c_adapter(adapter->dev.parent));
491 return rt_mutex_trylock(&adapter->bus_lock);
495 * i2c_unlock_adapter - Release exclusive access to an I2C bus segment
496 * @adapter: Target I2C bus segment
498 void i2c_unlock_adapter(struct i2c_adapter *adapter)
500 if (i2c_parent_is_i2c_adapter(adapter))
501 i2c_unlock_adapter(to_i2c_adapter(adapter->dev.parent));
503 rt_mutex_unlock(&adapter->bus_lock);
505 EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
508 * i2c_new_device - instantiate an i2c device
509 * @adap: the adapter managing the device
510 * @info: describes one I2C device; bus_num is ignored
513 * Create an i2c device. Binding is handled through driver model
514 * probe()/remove() methods. A driver may be bound to this device when we
515 * return from this function, or any later moment (e.g. maybe hotplugging will
516 * load the driver module). This call is not appropriate for use by mainboard
517 * initialization logic, which usually runs during an arch_initcall() long
518 * before any i2c_adapter could exist.
520 * This returns the new i2c client, which may be saved for later use with
521 * i2c_unregister_device(); or NULL to indicate an error.
524 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
526 struct i2c_client *client;
529 client = kzalloc(sizeof *client, GFP_KERNEL);
533 client->adapter = adap;
535 client->dev.platform_data = info->platform_data;
538 client->dev.archdata = *info->archdata;
540 client->flags = info->flags;
541 client->addr = info->addr;
542 client->irq = info->irq;
544 strlcpy(client->name, info->type, sizeof(client->name));
546 /* Check for address validity */
547 status = i2c_check_client_addr_validity(client);
549 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
550 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
554 /* Check for address business */
555 status = i2c_check_addr_busy(adap, client->addr);
559 client->dev.parent = &client->adapter->dev;
560 client->dev.bus = &i2c_bus_type;
561 client->dev.type = &i2c_client_type;
563 client->dev.of_node = info->of_node;
566 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
568 status = device_register(&client->dev);
572 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
573 client->name, dev_name(&client->dev));
578 dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
579 "(%d)\n", client->name, client->addr, status);
584 EXPORT_SYMBOL_GPL(i2c_new_device);
588 * i2c_unregister_device - reverse effect of i2c_new_device()
589 * @client: value returned from i2c_new_device()
592 void i2c_unregister_device(struct i2c_client *client)
594 device_unregister(&client->dev);
596 EXPORT_SYMBOL_GPL(i2c_unregister_device);
599 static const struct i2c_device_id dummy_id[] = {
604 static int dummy_probe(struct i2c_client *client,
605 const struct i2c_device_id *id)
610 static int dummy_remove(struct i2c_client *client)
615 static struct i2c_driver dummy_driver = {
616 .driver.name = "dummy",
617 .probe = dummy_probe,
618 .remove = dummy_remove,
619 .id_table = dummy_id,
623 * i2c_new_dummy - return a new i2c device bound to a dummy driver
624 * @adapter: the adapter managing the device
625 * @address: seven bit address to be used
628 * This returns an I2C client bound to the "dummy" driver, intended for use
629 * with devices that consume multiple addresses. Examples of such chips
630 * include various EEPROMS (like 24c04 and 24c08 models).
632 * These dummy devices have two main uses. First, most I2C and SMBus calls
633 * except i2c_transfer() need a client handle; the dummy will be that handle.
634 * And second, this prevents the specified address from being bound to a
637 * This returns the new i2c client, which should be saved for later use with
638 * i2c_unregister_device(); or NULL to indicate an error.
640 struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
642 struct i2c_board_info info = {
643 I2C_BOARD_INFO("dummy", address),
646 return i2c_new_device(adapter, &info);
648 EXPORT_SYMBOL_GPL(i2c_new_dummy);
650 /* ------------------------------------------------------------------------- */
652 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
654 static void i2c_adapter_dev_release(struct device *dev)
656 struct i2c_adapter *adap = to_i2c_adapter(dev);
657 complete(&adap->dev_released);
661 * Let users instantiate I2C devices through sysfs. This can be used when
662 * platform initialization code doesn't contain the proper data for
663 * whatever reason. Also useful for drivers that do device detection and
664 * detection fails, either because the device uses an unexpected address,
665 * or this is a compatible device with different ID register values.
667 * Parameter checking may look overzealous, but we really don't want
668 * the user to provide incorrect parameters.
671 i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
672 const char *buf, size_t count)
674 struct i2c_adapter *adap = to_i2c_adapter(dev);
675 struct i2c_board_info info;
676 struct i2c_client *client;
680 dev_warn(dev, "The new_device interface is still experimental "
681 "and may change in a near future\n");
682 memset(&info, 0, sizeof(struct i2c_board_info));
684 blank = strchr(buf, ' ');
686 dev_err(dev, "%s: Missing parameters\n", "new_device");
689 if (blank - buf > I2C_NAME_SIZE - 1) {
690 dev_err(dev, "%s: Invalid device name\n", "new_device");
693 memcpy(info.type, buf, blank - buf);
695 /* Parse remaining parameters, reject extra parameters */
696 res = sscanf(++blank, "%hi%c", &info.addr, &end);
698 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
701 if (res > 1 && end != '\n') {
702 dev_err(dev, "%s: Extra parameters\n", "new_device");
706 client = i2c_new_device(adap, &info);
710 /* Keep track of the added device */
711 mutex_lock(&adap->userspace_clients_lock);
712 list_add_tail(&client->detected, &adap->userspace_clients);
713 mutex_unlock(&adap->userspace_clients_lock);
714 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
715 info.type, info.addr);
721 * And of course let the users delete the devices they instantiated, if
722 * they got it wrong. This interface can only be used to delete devices
723 * instantiated by i2c_sysfs_new_device above. This guarantees that we
724 * don't delete devices to which some kernel code still has references.
726 * Parameter checking may look overzealous, but we really don't want
727 * the user to delete the wrong device.
730 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
731 const char *buf, size_t count)
733 struct i2c_adapter *adap = to_i2c_adapter(dev);
734 struct i2c_client *client, *next;
739 /* Parse parameters, reject extra parameters */
740 res = sscanf(buf, "%hi%c", &addr, &end);
742 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
745 if (res > 1 && end != '\n') {
746 dev_err(dev, "%s: Extra parameters\n", "delete_device");
750 /* Make sure the device was added through sysfs */
752 mutex_lock(&adap->userspace_clients_lock);
753 list_for_each_entry_safe(client, next, &adap->userspace_clients,
755 if (client->addr == addr) {
756 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
757 "delete_device", client->name, client->addr);
759 list_del(&client->detected);
760 i2c_unregister_device(client);
765 mutex_unlock(&adap->userspace_clients_lock);
768 dev_err(dev, "%s: Can't find device in list\n",
773 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
774 static DEVICE_ATTR(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device);
776 static struct attribute *i2c_adapter_attrs[] = {
778 &dev_attr_new_device.attr,
779 &dev_attr_delete_device.attr,
783 static struct attribute_group i2c_adapter_attr_group = {
784 .attrs = i2c_adapter_attrs,
787 static const struct attribute_group *i2c_adapter_attr_groups[] = {
788 &i2c_adapter_attr_group,
792 struct device_type i2c_adapter_type = {
793 .groups = i2c_adapter_attr_groups,
794 .release = i2c_adapter_dev_release,
796 EXPORT_SYMBOL_GPL(i2c_adapter_type);
798 #ifdef CONFIG_I2C_COMPAT
799 static struct class_compat *i2c_adapter_compat_class;
802 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
804 struct i2c_devinfo *devinfo;
806 down_read(&__i2c_board_lock);
807 list_for_each_entry(devinfo, &__i2c_board_list, list) {
808 if (devinfo->busnum == adapter->nr
809 && !i2c_new_device(adapter,
810 &devinfo->board_info))
811 dev_err(&adapter->dev,
812 "Can't create device at 0x%02x\n",
813 devinfo->board_info.addr);
815 up_read(&__i2c_board_lock);
818 static int i2c_do_add_adapter(struct i2c_driver *driver,
819 struct i2c_adapter *adap)
821 /* Detect supported devices on that bus, and instantiate them */
822 i2c_detect(adap, driver);
824 /* Let legacy drivers scan this bus for matching devices */
825 if (driver->attach_adapter) {
826 /* We ignore the return code; if it fails, too bad */
827 driver->attach_adapter(adap);
832 static int __process_new_adapter(struct device_driver *d, void *data)
834 return i2c_do_add_adapter(to_i2c_driver(d), data);
837 static int i2c_register_adapter(struct i2c_adapter *adap)
841 /* Can't register until after driver model init */
842 if (unlikely(WARN_ON(!i2c_bus_type.p))) {
847 rt_mutex_init(&adap->bus_lock);
848 mutex_init(&adap->userspace_clients_lock);
849 INIT_LIST_HEAD(&adap->userspace_clients);
851 /* Set default timeout to 1 second if not already set */
852 if (adap->timeout == 0)
855 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
856 adap->dev.bus = &i2c_bus_type;
857 adap->dev.type = &i2c_adapter_type;
858 res = device_register(&adap->dev);
862 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
864 #ifdef CONFIG_I2C_COMPAT
865 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
869 "Failed to create compatibility class link\n");
872 /* create pre-declared device nodes */
873 if (adap->nr < __i2c_first_dynamic_bus_num)
874 i2c_scan_static_board_info(adap);
877 mutex_lock(&core_lock);
878 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
879 mutex_unlock(&core_lock);
884 mutex_lock(&core_lock);
885 idr_remove(&i2c_adapter_idr, adap->nr);
886 mutex_unlock(&core_lock);
891 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
892 * @adapter: the adapter to add
895 * This routine is used to declare an I2C adapter when its bus number
896 * doesn't matter. Examples: for I2C adapters dynamically added by
897 * USB links or PCI plugin cards.
899 * When this returns zero, a new bus number was allocated and stored
900 * in adap->nr, and the specified adapter became available for clients.
901 * Otherwise, a negative errno value is returned.
903 int i2c_add_adapter(struct i2c_adapter *adapter)
908 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
911 mutex_lock(&core_lock);
912 /* "above" here means "above or equal to", sigh */
913 res = idr_get_new_above(&i2c_adapter_idr, adapter,
914 __i2c_first_dynamic_bus_num, &id);
915 mutex_unlock(&core_lock);
924 return i2c_register_adapter(adapter);
926 EXPORT_SYMBOL(i2c_add_adapter);
929 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
930 * @adap: the adapter to register (with adap->nr initialized)
933 * This routine is used to declare an I2C adapter when its bus number
934 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
935 * or otherwise built in to the system's mainboard, and where i2c_board_info
936 * is used to properly configure I2C devices.
938 * If no devices have pre-been declared for this bus, then be sure to
939 * register the adapter before any dynamically allocated ones. Otherwise
940 * the required bus ID may not be available.
942 * When this returns zero, the specified adapter became available for
943 * clients using the bus number provided in adap->nr. Also, the table
944 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
945 * and the appropriate driver model device nodes are created. Otherwise, a
946 * negative errno value is returned.
948 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
953 if (adap->nr & ~MAX_ID_MASK)
957 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
960 mutex_lock(&core_lock);
961 /* "above" here means "above or equal to", sigh;
962 * we need the "equal to" result to force the result
964 status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
965 if (status == 0 && id != adap->nr) {
967 idr_remove(&i2c_adapter_idr, id);
969 mutex_unlock(&core_lock);
970 if (status == -EAGAIN)
974 status = i2c_register_adapter(adap);
977 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
979 static int i2c_do_del_adapter(struct i2c_driver *driver,
980 struct i2c_adapter *adapter)
982 struct i2c_client *client, *_n;
985 /* Remove the devices we created ourselves as the result of hardware
986 * probing (using a driver's detect method) */
987 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
988 if (client->adapter == adapter) {
989 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
990 client->name, client->addr);
991 list_del(&client->detected);
992 i2c_unregister_device(client);
996 if (!driver->detach_adapter)
998 res = driver->detach_adapter(adapter);
1000 dev_err(&adapter->dev, "detach_adapter failed (%d) "
1001 "for driver [%s]\n", res, driver->driver.name);
1005 static int __unregister_client(struct device *dev, void *dummy)
1007 struct i2c_client *client = i2c_verify_client(dev);
1008 if (client && strcmp(client->name, "dummy"))
1009 i2c_unregister_device(client);
1013 static int __unregister_dummy(struct device *dev, void *dummy)
1015 struct i2c_client *client = i2c_verify_client(dev);
1017 i2c_unregister_device(client);
1021 static int __process_removed_adapter(struct device_driver *d, void *data)
1023 return i2c_do_del_adapter(to_i2c_driver(d), data);
1027 * i2c_del_adapter - unregister I2C adapter
1028 * @adap: the adapter being unregistered
1029 * Context: can sleep
1031 * This unregisters an I2C adapter which was previously registered
1032 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1034 int i2c_del_adapter(struct i2c_adapter *adap)
1037 struct i2c_adapter *found;
1038 struct i2c_client *client, *next;
1040 /* First make sure that this adapter was ever added */
1041 mutex_lock(&core_lock);
1042 found = idr_find(&i2c_adapter_idr, adap->nr);
1043 mutex_unlock(&core_lock);
1044 if (found != adap) {
1045 pr_debug("i2c-core: attempting to delete unregistered "
1046 "adapter [%s]\n", adap->name);
1050 /* Tell drivers about this removal */
1051 mutex_lock(&core_lock);
1052 res = bus_for_each_drv(&i2c_bus_type, NULL, adap,
1053 __process_removed_adapter);
1054 mutex_unlock(&core_lock);
1058 /* Remove devices instantiated from sysfs */
1059 mutex_lock(&adap->userspace_clients_lock);
1060 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1062 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1064 list_del(&client->detected);
1065 i2c_unregister_device(client);
1067 mutex_unlock(&adap->userspace_clients_lock);
1069 /* Detach any active clients. This can't fail, thus we do not
1070 * check the returned value. This is a two-pass process, because
1071 * we can't remove the dummy devices during the first pass: they
1072 * could have been instantiated by real devices wishing to clean
1073 * them up properly, so we give them a chance to do that first. */
1074 res = device_for_each_child(&adap->dev, NULL, __unregister_client);
1075 res = device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1077 #ifdef CONFIG_I2C_COMPAT
1078 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1082 /* device name is gone after device_unregister */
1083 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1085 /* clean up the sysfs representation */
1086 init_completion(&adap->dev_released);
1087 device_unregister(&adap->dev);
1089 /* wait for sysfs to drop all references */
1090 wait_for_completion(&adap->dev_released);
1093 mutex_lock(&core_lock);
1094 idr_remove(&i2c_adapter_idr, adap->nr);
1095 mutex_unlock(&core_lock);
1097 /* Clear the device structure in case this adapter is ever going to be
1099 memset(&adap->dev, 0, sizeof(adap->dev));
1103 EXPORT_SYMBOL(i2c_del_adapter);
1106 /* ------------------------------------------------------------------------- */
1108 static int __process_new_driver(struct device *dev, void *data)
1110 if (dev->type != &i2c_adapter_type)
1112 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1116 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1117 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1120 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1124 /* Can't register until after driver model init */
1125 if (unlikely(WARN_ON(!i2c_bus_type.p)))
1128 /* add the driver to the list of i2c drivers in the driver core */
1129 driver->driver.owner = owner;
1130 driver->driver.bus = &i2c_bus_type;
1132 /* When registration returns, the driver core
1133 * will have called probe() for all matching-but-unbound devices.
1135 res = driver_register(&driver->driver);
1139 pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
1141 INIT_LIST_HEAD(&driver->clients);
1142 /* Walk the adapters that are already present */
1143 mutex_lock(&core_lock);
1144 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_new_driver);
1145 mutex_unlock(&core_lock);
1149 EXPORT_SYMBOL(i2c_register_driver);
1151 static int __process_removed_driver(struct device *dev, void *data)
1153 if (dev->type != &i2c_adapter_type)
1155 return i2c_do_del_adapter(data, to_i2c_adapter(dev));
1159 * i2c_del_driver - unregister I2C driver
1160 * @driver: the driver being unregistered
1161 * Context: can sleep
1163 void i2c_del_driver(struct i2c_driver *driver)
1165 mutex_lock(&core_lock);
1166 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_removed_driver);
1167 mutex_unlock(&core_lock);
1169 driver_unregister(&driver->driver);
1170 pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
1172 EXPORT_SYMBOL(i2c_del_driver);
1174 /* ------------------------------------------------------------------------- */
1177 * i2c_use_client - increments the reference count of the i2c client structure
1178 * @client: the client being referenced
1180 * Each live reference to a client should be refcounted. The driver model does
1181 * that automatically as part of driver binding, so that most drivers don't
1182 * need to do this explicitly: they hold a reference until they're unbound
1185 * A pointer to the client with the incremented reference counter is returned.
1187 struct i2c_client *i2c_use_client(struct i2c_client *client)
1189 if (client && get_device(&client->dev))
1193 EXPORT_SYMBOL(i2c_use_client);
1196 * i2c_release_client - release a use of the i2c client structure
1197 * @client: the client being no longer referenced
1199 * Must be called when a user of a client is finished with it.
1201 void i2c_release_client(struct i2c_client *client)
1204 put_device(&client->dev);
1206 EXPORT_SYMBOL(i2c_release_client);
1208 struct i2c_cmd_arg {
1213 static int i2c_cmd(struct device *dev, void *_arg)
1215 struct i2c_client *client = i2c_verify_client(dev);
1216 struct i2c_cmd_arg *arg = _arg;
1218 if (client && client->driver && client->driver->command)
1219 client->driver->command(client, arg->cmd, arg->arg);
1223 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1225 struct i2c_cmd_arg cmd_arg;
1229 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1231 EXPORT_SYMBOL(i2c_clients_command);
1233 static int __init i2c_init(void)
1237 retval = bus_register(&i2c_bus_type);
1240 #ifdef CONFIG_I2C_COMPAT
1241 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1242 if (!i2c_adapter_compat_class) {
1247 retval = i2c_add_driver(&dummy_driver);
1253 #ifdef CONFIG_I2C_COMPAT
1254 class_compat_unregister(i2c_adapter_compat_class);
1257 bus_unregister(&i2c_bus_type);
1261 static void __exit i2c_exit(void)
1263 i2c_del_driver(&dummy_driver);
1264 #ifdef CONFIG_I2C_COMPAT
1265 class_compat_unregister(i2c_adapter_compat_class);
1267 bus_unregister(&i2c_bus_type);
1270 /* We must initialize early, because some subsystems register i2c drivers
1271 * in subsys_initcall() code, but are linked (and initialized) before i2c.
1273 postcore_initcall(i2c_init);
1274 module_exit(i2c_exit);
1276 /* ----------------------------------------------------
1277 * the functional interface to the i2c busses.
1278 * ----------------------------------------------------
1282 * i2c_transfer - execute a single or combined I2C message
1283 * @adap: Handle to I2C bus
1284 * @msgs: One or more messages to execute before STOP is issued to
1285 * terminate the operation; each message begins with a START.
1286 * @num: Number of messages to be executed.
1288 * Returns negative errno, else the number of messages executed.
1290 * Note that there is no requirement that each message be sent to
1291 * the same slave address, although that is the most common model.
1293 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1295 unsigned long orig_jiffies;
1298 /* REVISIT the fault reporting model here is weak:
1300 * - When we get an error after receiving N bytes from a slave,
1301 * there is no way to report "N".
1303 * - When we get a NAK after transmitting N bytes to a slave,
1304 * there is no way to report "N" ... or to let the master
1305 * continue executing the rest of this combined message, if
1306 * that's the appropriate response.
1308 * - When for example "num" is two and we successfully complete
1309 * the first message but get an error part way through the
1310 * second, it's unclear whether that should be reported as
1311 * one (discarding status on the second message) or errno
1312 * (discarding status on the first one).
1315 if (adap->algo->master_xfer) {
1317 for (ret = 0; ret < num; ret++) {
1318 dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
1319 "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
1320 ? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
1321 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1325 if (in_atomic() || irqs_disabled()) {
1326 ret = i2c_trylock_adapter(adap);
1328 /* I2C activity is ongoing. */
1331 i2c_lock_adapter(adap);
1334 /* Retry automatically on arbitration loss */
1335 orig_jiffies = jiffies;
1336 for (ret = 0, try = 0; try <= adap->retries; try++) {
1337 ret = adap->algo->master_xfer(adap, msgs, num);
1340 if (time_after(jiffies, orig_jiffies + adap->timeout))
1343 i2c_unlock_adapter(adap);
1347 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1351 EXPORT_SYMBOL(i2c_transfer);
1354 * i2c_master_send - issue a single I2C message in master transmit mode
1355 * @client: Handle to slave device
1356 * @buf: Data that will be written to the slave
1357 * @count: How many bytes to write, must be less than 64k since msg.len is u16
1359 * Returns negative errno, or else the number of bytes written.
1361 int i2c_master_send(struct i2c_client *client, const char *buf, int count)
1364 struct i2c_adapter *adap = client->adapter;
1367 msg.addr = client->addr;
1368 msg.flags = client->flags & I2C_M_TEN;
1370 msg.buf = (char *)buf;
1372 ret = i2c_transfer(adap, &msg, 1);
1374 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1375 transmitted, else error code. */
1376 return (ret == 1) ? count : ret;
1378 EXPORT_SYMBOL(i2c_master_send);
1381 * i2c_master_recv - issue a single I2C message in master receive mode
1382 * @client: Handle to slave device
1383 * @buf: Where to store data read from slave
1384 * @count: How many bytes to read, must be less than 64k since msg.len is u16
1386 * Returns negative errno, or else the number of bytes read.
1388 int i2c_master_recv(struct i2c_client *client, char *buf, int count)
1390 struct i2c_adapter *adap = client->adapter;
1394 msg.addr = client->addr;
1395 msg.flags = client->flags & I2C_M_TEN;
1396 msg.flags |= I2C_M_RD;
1400 ret = i2c_transfer(adap, &msg, 1);
1402 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1403 transmitted, else error code. */
1404 return (ret == 1) ? count : ret;
1406 EXPORT_SYMBOL(i2c_master_recv);
1408 /* ----------------------------------------------------
1409 * the i2c address scanning function
1410 * Will not work for 10-bit addresses!
1411 * ----------------------------------------------------
1415 * Legacy default probe function, mostly relevant for SMBus. The default
1416 * probe method is a quick write, but it is known to corrupt the 24RF08
1417 * EEPROMs due to a state machine bug, and could also irreversibly
1418 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
1419 * we use a short byte read instead. Also, some bus drivers don't implement
1420 * quick write, so we fallback to a byte read in that case too.
1421 * On x86, there is another special case for FSC hardware monitoring chips,
1422 * which want regular byte reads (address 0x73.) Fortunately, these are the
1423 * only known chips using this I2C address on PC hardware.
1424 * Returns 1 if probe succeeded, 0 if not.
1426 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
1429 union i2c_smbus_data dummy;
1432 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
1433 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
1434 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1435 I2C_SMBUS_BYTE_DATA, &dummy);
1438 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
1439 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
1440 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
1441 I2C_SMBUS_QUICK, NULL);
1442 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
1443 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1444 I2C_SMBUS_BYTE, &dummy);
1446 dev_warn(&adap->dev, "No suitable probing method supported\n");
1453 static int i2c_detect_address(struct i2c_client *temp_client,
1454 struct i2c_driver *driver)
1456 struct i2c_board_info info;
1457 struct i2c_adapter *adapter = temp_client->adapter;
1458 int addr = temp_client->addr;
1461 /* Make sure the address is valid */
1462 err = i2c_check_addr_validity(addr);
1464 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
1469 /* Skip if already in use */
1470 if (i2c_check_addr_busy(adapter, addr))
1473 /* Make sure there is something at this address */
1474 if (!i2c_default_probe(adapter, addr))
1477 /* Finally call the custom detection function */
1478 memset(&info, 0, sizeof(struct i2c_board_info));
1480 err = driver->detect(temp_client, &info);
1482 /* -ENODEV is returned if the detection fails. We catch it
1483 here as this isn't an error. */
1484 return err == -ENODEV ? 0 : err;
1487 /* Consistency check */
1488 if (info.type[0] == '\0') {
1489 dev_err(&adapter->dev, "%s detection function provided "
1490 "no name for 0x%x\n", driver->driver.name,
1493 struct i2c_client *client;
1495 /* Detection succeeded, instantiate the device */
1496 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
1497 info.type, info.addr);
1498 client = i2c_new_device(adapter, &info);
1500 list_add_tail(&client->detected, &driver->clients);
1502 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
1503 info.type, info.addr);
1508 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
1510 const unsigned short *address_list;
1511 struct i2c_client *temp_client;
1513 int adap_id = i2c_adapter_id(adapter);
1515 address_list = driver->address_list;
1516 if (!driver->detect || !address_list)
1519 /* Set up a temporary client to help detect callback */
1520 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
1523 temp_client->adapter = adapter;
1525 /* Stop here if the classes do not match */
1526 if (!(adapter->class & driver->class))
1529 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
1530 dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
1531 "addr 0x%02x\n", adap_id, address_list[i]);
1532 temp_client->addr = address_list[i];
1533 err = i2c_detect_address(temp_client, driver);
1543 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
1545 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1546 I2C_SMBUS_QUICK, NULL) >= 0;
1548 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
1551 i2c_new_probed_device(struct i2c_adapter *adap,
1552 struct i2c_board_info *info,
1553 unsigned short const *addr_list,
1554 int (*probe)(struct i2c_adapter *, unsigned short addr))
1559 probe = i2c_default_probe;
1561 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
1562 /* Check address validity */
1563 if (i2c_check_addr_validity(addr_list[i]) < 0) {
1564 dev_warn(&adap->dev, "Invalid 7-bit address "
1565 "0x%02x\n", addr_list[i]);
1569 /* Check address availability */
1570 if (i2c_check_addr_busy(adap, addr_list[i])) {
1571 dev_dbg(&adap->dev, "Address 0x%02x already in "
1572 "use, not probing\n", addr_list[i]);
1576 /* Test address responsiveness */
1577 if (probe(adap, addr_list[i]))
1581 if (addr_list[i] == I2C_CLIENT_END) {
1582 dev_dbg(&adap->dev, "Probing failed, no device found\n");
1586 info->addr = addr_list[i];
1587 return i2c_new_device(adap, info);
1589 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
1591 struct i2c_adapter *i2c_get_adapter(int id)
1593 struct i2c_adapter *adapter;
1595 mutex_lock(&core_lock);
1596 adapter = idr_find(&i2c_adapter_idr, id);
1597 if (adapter && !try_module_get(adapter->owner))
1600 mutex_unlock(&core_lock);
1603 EXPORT_SYMBOL(i2c_get_adapter);
1605 void i2c_put_adapter(struct i2c_adapter *adap)
1607 module_put(adap->owner);
1609 EXPORT_SYMBOL(i2c_put_adapter);
1611 /* The SMBus parts */
1613 #define POLY (0x1070U << 3)
1614 static u8 crc8(u16 data)
1618 for (i = 0; i < 8; i++) {
1623 return (u8)(data >> 8);
1626 /* Incremental CRC8 over count bytes in the array pointed to by p */
1627 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
1631 for (i = 0; i < count; i++)
1632 crc = crc8((crc ^ p[i]) << 8);
1636 /* Assume a 7-bit address, which is reasonable for SMBus */
1637 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
1639 /* The address will be sent first */
1640 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
1641 pec = i2c_smbus_pec(pec, &addr, 1);
1643 /* The data buffer follows */
1644 return i2c_smbus_pec(pec, msg->buf, msg->len);
1647 /* Used for write only transactions */
1648 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
1650 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
1654 /* Return <0 on CRC error
1655 If there was a write before this read (most cases) we need to take the
1656 partial CRC from the write part into account.
1657 Note that this function does modify the message (we need to decrease the
1658 message length to hide the CRC byte from the caller). */
1659 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
1661 u8 rpec = msg->buf[--msg->len];
1662 cpec = i2c_smbus_msg_pec(cpec, msg);
1665 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
1673 * i2c_smbus_read_byte - SMBus "receive byte" protocol
1674 * @client: Handle to slave device
1676 * This executes the SMBus "receive byte" protocol, returning negative errno
1677 * else the byte received from the device.
1679 s32 i2c_smbus_read_byte(struct i2c_client *client)
1681 union i2c_smbus_data data;
1684 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1686 I2C_SMBUS_BYTE, &data);
1687 return (status < 0) ? status : data.byte;
1689 EXPORT_SYMBOL(i2c_smbus_read_byte);
1692 * i2c_smbus_write_byte - SMBus "send byte" protocol
1693 * @client: Handle to slave device
1694 * @value: Byte to be sent
1696 * This executes the SMBus "send byte" protocol, returning negative errno
1697 * else zero on success.
1699 s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value)
1701 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1702 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
1704 EXPORT_SYMBOL(i2c_smbus_write_byte);
1707 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
1708 * @client: Handle to slave device
1709 * @command: Byte interpreted by slave
1711 * This executes the SMBus "read byte" protocol, returning negative errno
1712 * else a data byte received from the device.
1714 s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
1716 union i2c_smbus_data data;
1719 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1720 I2C_SMBUS_READ, command,
1721 I2C_SMBUS_BYTE_DATA, &data);
1722 return (status < 0) ? status : data.byte;
1724 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
1727 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
1728 * @client: Handle to slave device
1729 * @command: Byte interpreted by slave
1730 * @value: Byte being written
1732 * This executes the SMBus "write byte" protocol, returning negative errno
1733 * else zero on success.
1735 s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value)
1737 union i2c_smbus_data data;
1739 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1740 I2C_SMBUS_WRITE, command,
1741 I2C_SMBUS_BYTE_DATA, &data);
1743 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
1746 * i2c_smbus_read_word_data - SMBus "read word" protocol
1747 * @client: Handle to slave device
1748 * @command: Byte interpreted by slave
1750 * This executes the SMBus "read word" protocol, returning negative errno
1751 * else a 16-bit unsigned "word" received from the device.
1753 s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
1755 union i2c_smbus_data data;
1758 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1759 I2C_SMBUS_READ, command,
1760 I2C_SMBUS_WORD_DATA, &data);
1761 return (status < 0) ? status : data.word;
1763 EXPORT_SYMBOL(i2c_smbus_read_word_data);
1766 * i2c_smbus_write_word_data - SMBus "write word" protocol
1767 * @client: Handle to slave device
1768 * @command: Byte interpreted by slave
1769 * @value: 16-bit "word" being written
1771 * This executes the SMBus "write word" protocol, returning negative errno
1772 * else zero on success.
1774 s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
1776 union i2c_smbus_data data;
1778 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1779 I2C_SMBUS_WRITE, command,
1780 I2C_SMBUS_WORD_DATA, &data);
1782 EXPORT_SYMBOL(i2c_smbus_write_word_data);
1785 * i2c_smbus_process_call - SMBus "process call" protocol
1786 * @client: Handle to slave device
1787 * @command: Byte interpreted by slave
1788 * @value: 16-bit "word" being written
1790 * This executes the SMBus "process call" protocol, returning negative errno
1791 * else a 16-bit unsigned "word" received from the device.
1793 s32 i2c_smbus_process_call(struct i2c_client *client, u8 command, u16 value)
1795 union i2c_smbus_data data;
1799 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1800 I2C_SMBUS_WRITE, command,
1801 I2C_SMBUS_PROC_CALL, &data);
1802 return (status < 0) ? status : data.word;
1804 EXPORT_SYMBOL(i2c_smbus_process_call);
1807 * i2c_smbus_read_block_data - SMBus "block read" protocol
1808 * @client: Handle to slave device
1809 * @command: Byte interpreted by slave
1810 * @values: Byte array into which data will be read; big enough to hold
1811 * the data returned by the slave. SMBus allows at most 32 bytes.
1813 * This executes the SMBus "block read" protocol, returning negative errno
1814 * else the number of data bytes in the slave's response.
1816 * Note that using this function requires that the client's adapter support
1817 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
1818 * support this; its emulation through I2C messaging relies on a specific
1819 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
1821 s32 i2c_smbus_read_block_data(struct i2c_client *client, u8 command,
1824 union i2c_smbus_data data;
1827 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1828 I2C_SMBUS_READ, command,
1829 I2C_SMBUS_BLOCK_DATA, &data);
1833 memcpy(values, &data.block[1], data.block[0]);
1834 return data.block[0];
1836 EXPORT_SYMBOL(i2c_smbus_read_block_data);
1839 * i2c_smbus_write_block_data - SMBus "block write" protocol
1840 * @client: Handle to slave device
1841 * @command: Byte interpreted by slave
1842 * @length: Size of data block; SMBus allows at most 32 bytes
1843 * @values: Byte array which will be written.
1845 * This executes the SMBus "block write" protocol, returning negative errno
1846 * else zero on success.
1848 s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
1849 u8 length, const u8 *values)
1851 union i2c_smbus_data data;
1853 if (length > I2C_SMBUS_BLOCK_MAX)
1854 length = I2C_SMBUS_BLOCK_MAX;
1855 data.block[0] = length;
1856 memcpy(&data.block[1], values, length);
1857 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1858 I2C_SMBUS_WRITE, command,
1859 I2C_SMBUS_BLOCK_DATA, &data);
1861 EXPORT_SYMBOL(i2c_smbus_write_block_data);
1863 /* Returns the number of read bytes */
1864 s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
1865 u8 length, u8 *values)
1867 union i2c_smbus_data data;
1870 if (length > I2C_SMBUS_BLOCK_MAX)
1871 length = I2C_SMBUS_BLOCK_MAX;
1872 data.block[0] = length;
1873 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1874 I2C_SMBUS_READ, command,
1875 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1879 memcpy(values, &data.block[1], data.block[0]);
1880 return data.block[0];
1882 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
1884 s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command,
1885 u8 length, const u8 *values)
1887 union i2c_smbus_data data;
1889 if (length > I2C_SMBUS_BLOCK_MAX)
1890 length = I2C_SMBUS_BLOCK_MAX;
1891 data.block[0] = length;
1892 memcpy(data.block + 1, values, length);
1893 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1894 I2C_SMBUS_WRITE, command,
1895 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1897 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
1899 /* Simulate a SMBus command using the i2c protocol
1900 No checking of parameters is done! */
1901 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
1902 unsigned short flags,
1903 char read_write, u8 command, int size,
1904 union i2c_smbus_data *data)
1906 /* So we need to generate a series of msgs. In the case of writing, we
1907 need to use only one message; when reading, we need two. We initialize
1908 most things with sane defaults, to keep the code below somewhat
1910 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
1911 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
1912 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
1913 struct i2c_msg msg[2] = { { addr, flags, 1, msgbuf0 },
1914 { addr, flags | I2C_M_RD, 0, msgbuf1 }
1920 msgbuf0[0] = command;
1922 case I2C_SMBUS_QUICK:
1924 /* Special case: The read/write field is used as data */
1925 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
1929 case I2C_SMBUS_BYTE:
1930 if (read_write == I2C_SMBUS_READ) {
1931 /* Special case: only a read! */
1932 msg[0].flags = I2C_M_RD | flags;
1936 case I2C_SMBUS_BYTE_DATA:
1937 if (read_write == I2C_SMBUS_READ)
1941 msgbuf0[1] = data->byte;
1944 case I2C_SMBUS_WORD_DATA:
1945 if (read_write == I2C_SMBUS_READ)
1949 msgbuf0[1] = data->word & 0xff;
1950 msgbuf0[2] = data->word >> 8;
1953 case I2C_SMBUS_PROC_CALL:
1954 num = 2; /* Special case */
1955 read_write = I2C_SMBUS_READ;
1958 msgbuf0[1] = data->word & 0xff;
1959 msgbuf0[2] = data->word >> 8;
1961 case I2C_SMBUS_BLOCK_DATA:
1962 if (read_write == I2C_SMBUS_READ) {
1963 msg[1].flags |= I2C_M_RECV_LEN;
1964 msg[1].len = 1; /* block length will be added by
1965 the underlying bus driver */
1967 msg[0].len = data->block[0] + 2;
1968 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
1969 dev_err(&adapter->dev,
1970 "Invalid block write size %d\n",
1974 for (i = 1; i < msg[0].len; i++)
1975 msgbuf0[i] = data->block[i-1];
1978 case I2C_SMBUS_BLOCK_PROC_CALL:
1979 num = 2; /* Another special case */
1980 read_write = I2C_SMBUS_READ;
1981 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
1982 dev_err(&adapter->dev,
1983 "Invalid block write size %d\n",
1987 msg[0].len = data->block[0] + 2;
1988 for (i = 1; i < msg[0].len; i++)
1989 msgbuf0[i] = data->block[i-1];
1990 msg[1].flags |= I2C_M_RECV_LEN;
1991 msg[1].len = 1; /* block length will be added by
1992 the underlying bus driver */
1994 case I2C_SMBUS_I2C_BLOCK_DATA:
1995 if (read_write == I2C_SMBUS_READ) {
1996 msg[1].len = data->block[0];
1998 msg[0].len = data->block[0] + 1;
1999 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
2000 dev_err(&adapter->dev,
2001 "Invalid block write size %d\n",
2005 for (i = 1; i <= data->block[0]; i++)
2006 msgbuf0[i] = data->block[i];
2010 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
2014 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
2015 && size != I2C_SMBUS_I2C_BLOCK_DATA);
2017 /* Compute PEC if first message is a write */
2018 if (!(msg[0].flags & I2C_M_RD)) {
2019 if (num == 1) /* Write only */
2020 i2c_smbus_add_pec(&msg[0]);
2021 else /* Write followed by read */
2022 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
2024 /* Ask for PEC if last message is a read */
2025 if (msg[num-1].flags & I2C_M_RD)
2029 status = i2c_transfer(adapter, msg, num);
2033 /* Check PEC if last message is a read */
2034 if (i && (msg[num-1].flags & I2C_M_RD)) {
2035 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
2040 if (read_write == I2C_SMBUS_READ)
2042 case I2C_SMBUS_BYTE:
2043 data->byte = msgbuf0[0];
2045 case I2C_SMBUS_BYTE_DATA:
2046 data->byte = msgbuf1[0];
2048 case I2C_SMBUS_WORD_DATA:
2049 case I2C_SMBUS_PROC_CALL:
2050 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
2052 case I2C_SMBUS_I2C_BLOCK_DATA:
2053 for (i = 0; i < data->block[0]; i++)
2054 data->block[i+1] = msgbuf1[i];
2056 case I2C_SMBUS_BLOCK_DATA:
2057 case I2C_SMBUS_BLOCK_PROC_CALL:
2058 for (i = 0; i < msgbuf1[0] + 1; i++)
2059 data->block[i] = msgbuf1[i];
2066 * i2c_smbus_xfer - execute SMBus protocol operations
2067 * @adapter: Handle to I2C bus
2068 * @addr: Address of SMBus slave on that bus
2069 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
2070 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
2071 * @command: Byte interpreted by slave, for protocols which use such bytes
2072 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
2073 * @data: Data to be read or written
2075 * This executes an SMBus protocol operation, and returns a negative
2076 * errno code else zero on success.
2078 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
2079 char read_write, u8 command, int protocol,
2080 union i2c_smbus_data *data)
2082 unsigned long orig_jiffies;
2086 flags &= I2C_M_TEN | I2C_CLIENT_PEC;
2088 if (adapter->algo->smbus_xfer) {
2089 i2c_lock_adapter(adapter);
2091 /* Retry automatically on arbitration loss */
2092 orig_jiffies = jiffies;
2093 for (res = 0, try = 0; try <= adapter->retries; try++) {
2094 res = adapter->algo->smbus_xfer(adapter, addr, flags,
2095 read_write, command,
2099 if (time_after(jiffies,
2100 orig_jiffies + adapter->timeout))
2103 i2c_unlock_adapter(adapter);
2105 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
2106 command, protocol, data);
2110 EXPORT_SYMBOL(i2c_smbus_xfer);
2112 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2113 MODULE_DESCRIPTION("I2C-Bus main module");
2114 MODULE_LICENSE("GPL");