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);
1009 i2c_unregister_device(client);
1013 static int __process_removed_adapter(struct device_driver *d, void *data)
1015 return i2c_do_del_adapter(to_i2c_driver(d), data);
1019 * i2c_del_adapter - unregister I2C adapter
1020 * @adap: the adapter being unregistered
1021 * Context: can sleep
1023 * This unregisters an I2C adapter which was previously registered
1024 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1026 int i2c_del_adapter(struct i2c_adapter *adap)
1029 struct i2c_adapter *found;
1030 struct i2c_client *client, *next;
1032 /* First make sure that this adapter was ever added */
1033 mutex_lock(&core_lock);
1034 found = idr_find(&i2c_adapter_idr, adap->nr);
1035 mutex_unlock(&core_lock);
1036 if (found != adap) {
1037 pr_debug("i2c-core: attempting to delete unregistered "
1038 "adapter [%s]\n", adap->name);
1042 /* Tell drivers about this removal */
1043 mutex_lock(&core_lock);
1044 res = bus_for_each_drv(&i2c_bus_type, NULL, adap,
1045 __process_removed_adapter);
1046 mutex_unlock(&core_lock);
1050 /* Remove devices instantiated from sysfs */
1051 mutex_lock(&adap->userspace_clients_lock);
1052 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1054 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1056 list_del(&client->detected);
1057 i2c_unregister_device(client);
1059 mutex_unlock(&adap->userspace_clients_lock);
1061 /* Detach any active clients. This can't fail, thus we do not
1062 checking the returned value. */
1063 res = device_for_each_child(&adap->dev, NULL, __unregister_client);
1065 #ifdef CONFIG_I2C_COMPAT
1066 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1070 /* device name is gone after device_unregister */
1071 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1073 /* clean up the sysfs representation */
1074 init_completion(&adap->dev_released);
1075 device_unregister(&adap->dev);
1077 /* wait for sysfs to drop all references */
1078 wait_for_completion(&adap->dev_released);
1081 mutex_lock(&core_lock);
1082 idr_remove(&i2c_adapter_idr, adap->nr);
1083 mutex_unlock(&core_lock);
1085 /* Clear the device structure in case this adapter is ever going to be
1087 memset(&adap->dev, 0, sizeof(adap->dev));
1091 EXPORT_SYMBOL(i2c_del_adapter);
1094 /* ------------------------------------------------------------------------- */
1096 static int __process_new_driver(struct device *dev, void *data)
1098 if (dev->type != &i2c_adapter_type)
1100 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1104 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1105 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1108 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1112 /* Can't register until after driver model init */
1113 if (unlikely(WARN_ON(!i2c_bus_type.p)))
1116 /* add the driver to the list of i2c drivers in the driver core */
1117 driver->driver.owner = owner;
1118 driver->driver.bus = &i2c_bus_type;
1120 /* When registration returns, the driver core
1121 * will have called probe() for all matching-but-unbound devices.
1123 res = driver_register(&driver->driver);
1127 pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
1129 INIT_LIST_HEAD(&driver->clients);
1130 /* Walk the adapters that are already present */
1131 mutex_lock(&core_lock);
1132 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_new_driver);
1133 mutex_unlock(&core_lock);
1137 EXPORT_SYMBOL(i2c_register_driver);
1139 static int __process_removed_driver(struct device *dev, void *data)
1141 if (dev->type != &i2c_adapter_type)
1143 return i2c_do_del_adapter(data, to_i2c_adapter(dev));
1147 * i2c_del_driver - unregister I2C driver
1148 * @driver: the driver being unregistered
1149 * Context: can sleep
1151 void i2c_del_driver(struct i2c_driver *driver)
1153 mutex_lock(&core_lock);
1154 bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_removed_driver);
1155 mutex_unlock(&core_lock);
1157 driver_unregister(&driver->driver);
1158 pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
1160 EXPORT_SYMBOL(i2c_del_driver);
1162 /* ------------------------------------------------------------------------- */
1165 * i2c_use_client - increments the reference count of the i2c client structure
1166 * @client: the client being referenced
1168 * Each live reference to a client should be refcounted. The driver model does
1169 * that automatically as part of driver binding, so that most drivers don't
1170 * need to do this explicitly: they hold a reference until they're unbound
1173 * A pointer to the client with the incremented reference counter is returned.
1175 struct i2c_client *i2c_use_client(struct i2c_client *client)
1177 if (client && get_device(&client->dev))
1181 EXPORT_SYMBOL(i2c_use_client);
1184 * i2c_release_client - release a use of the i2c client structure
1185 * @client: the client being no longer referenced
1187 * Must be called when a user of a client is finished with it.
1189 void i2c_release_client(struct i2c_client *client)
1192 put_device(&client->dev);
1194 EXPORT_SYMBOL(i2c_release_client);
1196 struct i2c_cmd_arg {
1201 static int i2c_cmd(struct device *dev, void *_arg)
1203 struct i2c_client *client = i2c_verify_client(dev);
1204 struct i2c_cmd_arg *arg = _arg;
1206 if (client && client->driver && client->driver->command)
1207 client->driver->command(client, arg->cmd, arg->arg);
1211 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1213 struct i2c_cmd_arg cmd_arg;
1217 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1219 EXPORT_SYMBOL(i2c_clients_command);
1221 static int __init i2c_init(void)
1225 retval = bus_register(&i2c_bus_type);
1228 #ifdef CONFIG_I2C_COMPAT
1229 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1230 if (!i2c_adapter_compat_class) {
1235 retval = i2c_add_driver(&dummy_driver);
1241 #ifdef CONFIG_I2C_COMPAT
1242 class_compat_unregister(i2c_adapter_compat_class);
1245 bus_unregister(&i2c_bus_type);
1249 static void __exit i2c_exit(void)
1251 i2c_del_driver(&dummy_driver);
1252 #ifdef CONFIG_I2C_COMPAT
1253 class_compat_unregister(i2c_adapter_compat_class);
1255 bus_unregister(&i2c_bus_type);
1258 /* We must initialize early, because some subsystems register i2c drivers
1259 * in subsys_initcall() code, but are linked (and initialized) before i2c.
1261 postcore_initcall(i2c_init);
1262 module_exit(i2c_exit);
1264 /* ----------------------------------------------------
1265 * the functional interface to the i2c busses.
1266 * ----------------------------------------------------
1270 * i2c_transfer - execute a single or combined I2C message
1271 * @adap: Handle to I2C bus
1272 * @msgs: One or more messages to execute before STOP is issued to
1273 * terminate the operation; each message begins with a START.
1274 * @num: Number of messages to be executed.
1276 * Returns negative errno, else the number of messages executed.
1278 * Note that there is no requirement that each message be sent to
1279 * the same slave address, although that is the most common model.
1281 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1283 unsigned long orig_jiffies;
1286 /* REVISIT the fault reporting model here is weak:
1288 * - When we get an error after receiving N bytes from a slave,
1289 * there is no way to report "N".
1291 * - When we get a NAK after transmitting N bytes to a slave,
1292 * there is no way to report "N" ... or to let the master
1293 * continue executing the rest of this combined message, if
1294 * that's the appropriate response.
1296 * - When for example "num" is two and we successfully complete
1297 * the first message but get an error part way through the
1298 * second, it's unclear whether that should be reported as
1299 * one (discarding status on the second message) or errno
1300 * (discarding status on the first one).
1303 if (adap->algo->master_xfer) {
1305 for (ret = 0; ret < num; ret++) {
1306 dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
1307 "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
1308 ? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
1309 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1313 if (in_atomic() || irqs_disabled()) {
1314 ret = i2c_trylock_adapter(adap);
1316 /* I2C activity is ongoing. */
1319 i2c_lock_adapter(adap);
1322 /* Retry automatically on arbitration loss */
1323 orig_jiffies = jiffies;
1324 for (ret = 0, try = 0; try <= adap->retries; try++) {
1325 ret = adap->algo->master_xfer(adap, msgs, num);
1328 if (time_after(jiffies, orig_jiffies + adap->timeout))
1331 i2c_unlock_adapter(adap);
1335 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1339 EXPORT_SYMBOL(i2c_transfer);
1342 * i2c_master_send - issue a single I2C message in master transmit mode
1343 * @client: Handle to slave device
1344 * @buf: Data that will be written to the slave
1345 * @count: How many bytes to write, must be less than 64k since msg.len is u16
1347 * Returns negative errno, or else the number of bytes written.
1349 int i2c_master_send(struct i2c_client *client, const char *buf, int count)
1352 struct i2c_adapter *adap = client->adapter;
1355 msg.addr = client->addr;
1356 msg.flags = client->flags & I2C_M_TEN;
1358 msg.buf = (char *)buf;
1360 ret = i2c_transfer(adap, &msg, 1);
1362 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1363 transmitted, else error code. */
1364 return (ret == 1) ? count : ret;
1366 EXPORT_SYMBOL(i2c_master_send);
1369 * i2c_master_recv - issue a single I2C message in master receive mode
1370 * @client: Handle to slave device
1371 * @buf: Where to store data read from slave
1372 * @count: How many bytes to read, must be less than 64k since msg.len is u16
1374 * Returns negative errno, or else the number of bytes read.
1376 int i2c_master_recv(struct i2c_client *client, char *buf, int count)
1378 struct i2c_adapter *adap = client->adapter;
1382 msg.addr = client->addr;
1383 msg.flags = client->flags & I2C_M_TEN;
1384 msg.flags |= I2C_M_RD;
1388 ret = i2c_transfer(adap, &msg, 1);
1390 /* If everything went ok (i.e. 1 msg transmitted), return #bytes
1391 transmitted, else error code. */
1392 return (ret == 1) ? count : ret;
1394 EXPORT_SYMBOL(i2c_master_recv);
1396 /* ----------------------------------------------------
1397 * the i2c address scanning function
1398 * Will not work for 10-bit addresses!
1399 * ----------------------------------------------------
1403 * Legacy default probe function, mostly relevant for SMBus. The default
1404 * probe method is a quick write, but it is known to corrupt the 24RF08
1405 * EEPROMs due to a state machine bug, and could also irreversibly
1406 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
1407 * we use a short byte read instead. Also, some bus drivers don't implement
1408 * quick write, so we fallback to a byte read in that case too.
1409 * On x86, there is another special case for FSC hardware monitoring chips,
1410 * which want regular byte reads (address 0x73.) Fortunately, these are the
1411 * only known chips using this I2C address on PC hardware.
1412 * Returns 1 if probe succeeded, 0 if not.
1414 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
1417 union i2c_smbus_data dummy;
1420 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
1421 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
1422 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1423 I2C_SMBUS_BYTE_DATA, &dummy);
1426 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
1427 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
1428 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
1429 I2C_SMBUS_QUICK, NULL);
1430 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
1431 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1432 I2C_SMBUS_BYTE, &dummy);
1434 dev_warn(&adap->dev, "No suitable probing method supported\n");
1441 static int i2c_detect_address(struct i2c_client *temp_client,
1442 struct i2c_driver *driver)
1444 struct i2c_board_info info;
1445 struct i2c_adapter *adapter = temp_client->adapter;
1446 int addr = temp_client->addr;
1449 /* Make sure the address is valid */
1450 err = i2c_check_addr_validity(addr);
1452 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
1457 /* Skip if already in use */
1458 if (i2c_check_addr_busy(adapter, addr))
1461 /* Make sure there is something at this address */
1462 if (!i2c_default_probe(adapter, addr))
1465 /* Finally call the custom detection function */
1466 memset(&info, 0, sizeof(struct i2c_board_info));
1468 err = driver->detect(temp_client, &info);
1470 /* -ENODEV is returned if the detection fails. We catch it
1471 here as this isn't an error. */
1472 return err == -ENODEV ? 0 : err;
1475 /* Consistency check */
1476 if (info.type[0] == '\0') {
1477 dev_err(&adapter->dev, "%s detection function provided "
1478 "no name for 0x%x\n", driver->driver.name,
1481 struct i2c_client *client;
1483 /* Detection succeeded, instantiate the device */
1484 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
1485 info.type, info.addr);
1486 client = i2c_new_device(adapter, &info);
1488 list_add_tail(&client->detected, &driver->clients);
1490 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
1491 info.type, info.addr);
1496 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
1498 const unsigned short *address_list;
1499 struct i2c_client *temp_client;
1501 int adap_id = i2c_adapter_id(adapter);
1503 address_list = driver->address_list;
1504 if (!driver->detect || !address_list)
1507 /* Set up a temporary client to help detect callback */
1508 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
1511 temp_client->adapter = adapter;
1513 /* Stop here if the classes do not match */
1514 if (!(adapter->class & driver->class))
1517 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
1518 dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
1519 "addr 0x%02x\n", adap_id, address_list[i]);
1520 temp_client->addr = address_list[i];
1521 err = i2c_detect_address(temp_client, driver);
1531 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
1533 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1534 I2C_SMBUS_QUICK, NULL) >= 0;
1536 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
1539 i2c_new_probed_device(struct i2c_adapter *adap,
1540 struct i2c_board_info *info,
1541 unsigned short const *addr_list,
1542 int (*probe)(struct i2c_adapter *, unsigned short addr))
1547 probe = i2c_default_probe;
1549 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
1550 /* Check address validity */
1551 if (i2c_check_addr_validity(addr_list[i]) < 0) {
1552 dev_warn(&adap->dev, "Invalid 7-bit address "
1553 "0x%02x\n", addr_list[i]);
1557 /* Check address availability */
1558 if (i2c_check_addr_busy(adap, addr_list[i])) {
1559 dev_dbg(&adap->dev, "Address 0x%02x already in "
1560 "use, not probing\n", addr_list[i]);
1564 /* Test address responsiveness */
1565 if (probe(adap, addr_list[i]))
1569 if (addr_list[i] == I2C_CLIENT_END) {
1570 dev_dbg(&adap->dev, "Probing failed, no device found\n");
1574 info->addr = addr_list[i];
1575 return i2c_new_device(adap, info);
1577 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
1579 struct i2c_adapter *i2c_get_adapter(int id)
1581 struct i2c_adapter *adapter;
1583 mutex_lock(&core_lock);
1584 adapter = idr_find(&i2c_adapter_idr, id);
1585 if (adapter && !try_module_get(adapter->owner))
1588 mutex_unlock(&core_lock);
1591 EXPORT_SYMBOL(i2c_get_adapter);
1593 void i2c_put_adapter(struct i2c_adapter *adap)
1595 module_put(adap->owner);
1597 EXPORT_SYMBOL(i2c_put_adapter);
1599 /* The SMBus parts */
1601 #define POLY (0x1070U << 3)
1602 static u8 crc8(u16 data)
1606 for (i = 0; i < 8; i++) {
1611 return (u8)(data >> 8);
1614 /* Incremental CRC8 over count bytes in the array pointed to by p */
1615 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
1619 for (i = 0; i < count; i++)
1620 crc = crc8((crc ^ p[i]) << 8);
1624 /* Assume a 7-bit address, which is reasonable for SMBus */
1625 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
1627 /* The address will be sent first */
1628 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
1629 pec = i2c_smbus_pec(pec, &addr, 1);
1631 /* The data buffer follows */
1632 return i2c_smbus_pec(pec, msg->buf, msg->len);
1635 /* Used for write only transactions */
1636 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
1638 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
1642 /* Return <0 on CRC error
1643 If there was a write before this read (most cases) we need to take the
1644 partial CRC from the write part into account.
1645 Note that this function does modify the message (we need to decrease the
1646 message length to hide the CRC byte from the caller). */
1647 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
1649 u8 rpec = msg->buf[--msg->len];
1650 cpec = i2c_smbus_msg_pec(cpec, msg);
1653 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
1661 * i2c_smbus_read_byte - SMBus "receive byte" protocol
1662 * @client: Handle to slave device
1664 * This executes the SMBus "receive byte" protocol, returning negative errno
1665 * else the byte received from the device.
1667 s32 i2c_smbus_read_byte(struct i2c_client *client)
1669 union i2c_smbus_data data;
1672 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1674 I2C_SMBUS_BYTE, &data);
1675 return (status < 0) ? status : data.byte;
1677 EXPORT_SYMBOL(i2c_smbus_read_byte);
1680 * i2c_smbus_write_byte - SMBus "send byte" protocol
1681 * @client: Handle to slave device
1682 * @value: Byte to be sent
1684 * This executes the SMBus "send byte" protocol, returning negative errno
1685 * else zero on success.
1687 s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value)
1689 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1690 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
1692 EXPORT_SYMBOL(i2c_smbus_write_byte);
1695 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
1696 * @client: Handle to slave device
1697 * @command: Byte interpreted by slave
1699 * This executes the SMBus "read byte" protocol, returning negative errno
1700 * else a data byte received from the device.
1702 s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
1704 union i2c_smbus_data data;
1707 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1708 I2C_SMBUS_READ, command,
1709 I2C_SMBUS_BYTE_DATA, &data);
1710 return (status < 0) ? status : data.byte;
1712 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
1715 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
1716 * @client: Handle to slave device
1717 * @command: Byte interpreted by slave
1718 * @value: Byte being written
1720 * This executes the SMBus "write byte" protocol, returning negative errno
1721 * else zero on success.
1723 s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value)
1725 union i2c_smbus_data data;
1727 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1728 I2C_SMBUS_WRITE, command,
1729 I2C_SMBUS_BYTE_DATA, &data);
1731 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
1734 * i2c_smbus_read_word_data - SMBus "read word" protocol
1735 * @client: Handle to slave device
1736 * @command: Byte interpreted by slave
1738 * This executes the SMBus "read word" protocol, returning negative errno
1739 * else a 16-bit unsigned "word" received from the device.
1741 s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
1743 union i2c_smbus_data data;
1746 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1747 I2C_SMBUS_READ, command,
1748 I2C_SMBUS_WORD_DATA, &data);
1749 return (status < 0) ? status : data.word;
1751 EXPORT_SYMBOL(i2c_smbus_read_word_data);
1754 * i2c_smbus_write_word_data - SMBus "write word" protocol
1755 * @client: Handle to slave device
1756 * @command: Byte interpreted by slave
1757 * @value: 16-bit "word" being written
1759 * This executes the SMBus "write word" protocol, returning negative errno
1760 * else zero on success.
1762 s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
1764 union i2c_smbus_data data;
1766 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1767 I2C_SMBUS_WRITE, command,
1768 I2C_SMBUS_WORD_DATA, &data);
1770 EXPORT_SYMBOL(i2c_smbus_write_word_data);
1773 * i2c_smbus_process_call - SMBus "process call" protocol
1774 * @client: Handle to slave device
1775 * @command: Byte interpreted by slave
1776 * @value: 16-bit "word" being written
1778 * This executes the SMBus "process call" protocol, returning negative errno
1779 * else a 16-bit unsigned "word" received from the device.
1781 s32 i2c_smbus_process_call(struct i2c_client *client, u8 command, u16 value)
1783 union i2c_smbus_data data;
1787 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1788 I2C_SMBUS_WRITE, command,
1789 I2C_SMBUS_PROC_CALL, &data);
1790 return (status < 0) ? status : data.word;
1792 EXPORT_SYMBOL(i2c_smbus_process_call);
1795 * i2c_smbus_read_block_data - SMBus "block read" protocol
1796 * @client: Handle to slave device
1797 * @command: Byte interpreted by slave
1798 * @values: Byte array into which data will be read; big enough to hold
1799 * the data returned by the slave. SMBus allows at most 32 bytes.
1801 * This executes the SMBus "block read" protocol, returning negative errno
1802 * else the number of data bytes in the slave's response.
1804 * Note that using this function requires that the client's adapter support
1805 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
1806 * support this; its emulation through I2C messaging relies on a specific
1807 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
1809 s32 i2c_smbus_read_block_data(struct i2c_client *client, u8 command,
1812 union i2c_smbus_data data;
1815 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1816 I2C_SMBUS_READ, command,
1817 I2C_SMBUS_BLOCK_DATA, &data);
1821 memcpy(values, &data.block[1], data.block[0]);
1822 return data.block[0];
1824 EXPORT_SYMBOL(i2c_smbus_read_block_data);
1827 * i2c_smbus_write_block_data - SMBus "block write" protocol
1828 * @client: Handle to slave device
1829 * @command: Byte interpreted by slave
1830 * @length: Size of data block; SMBus allows at most 32 bytes
1831 * @values: Byte array which will be written.
1833 * This executes the SMBus "block write" protocol, returning negative errno
1834 * else zero on success.
1836 s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
1837 u8 length, const u8 *values)
1839 union i2c_smbus_data data;
1841 if (length > I2C_SMBUS_BLOCK_MAX)
1842 length = I2C_SMBUS_BLOCK_MAX;
1843 data.block[0] = length;
1844 memcpy(&data.block[1], values, length);
1845 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1846 I2C_SMBUS_WRITE, command,
1847 I2C_SMBUS_BLOCK_DATA, &data);
1849 EXPORT_SYMBOL(i2c_smbus_write_block_data);
1851 /* Returns the number of read bytes */
1852 s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
1853 u8 length, u8 *values)
1855 union i2c_smbus_data data;
1858 if (length > I2C_SMBUS_BLOCK_MAX)
1859 length = I2C_SMBUS_BLOCK_MAX;
1860 data.block[0] = length;
1861 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1862 I2C_SMBUS_READ, command,
1863 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1867 memcpy(values, &data.block[1], data.block[0]);
1868 return data.block[0];
1870 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
1872 s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command,
1873 u8 length, const u8 *values)
1875 union i2c_smbus_data data;
1877 if (length > I2C_SMBUS_BLOCK_MAX)
1878 length = I2C_SMBUS_BLOCK_MAX;
1879 data.block[0] = length;
1880 memcpy(data.block + 1, values, length);
1881 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1882 I2C_SMBUS_WRITE, command,
1883 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1885 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
1887 /* Simulate a SMBus command using the i2c protocol
1888 No checking of parameters is done! */
1889 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
1890 unsigned short flags,
1891 char read_write, u8 command, int size,
1892 union i2c_smbus_data *data)
1894 /* So we need to generate a series of msgs. In the case of writing, we
1895 need to use only one message; when reading, we need two. We initialize
1896 most things with sane defaults, to keep the code below somewhat
1898 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
1899 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
1900 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
1901 struct i2c_msg msg[2] = { { addr, flags, 1, msgbuf0 },
1902 { addr, flags | I2C_M_RD, 0, msgbuf1 }
1908 msgbuf0[0] = command;
1910 case I2C_SMBUS_QUICK:
1912 /* Special case: The read/write field is used as data */
1913 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
1917 case I2C_SMBUS_BYTE:
1918 if (read_write == I2C_SMBUS_READ) {
1919 /* Special case: only a read! */
1920 msg[0].flags = I2C_M_RD | flags;
1924 case I2C_SMBUS_BYTE_DATA:
1925 if (read_write == I2C_SMBUS_READ)
1929 msgbuf0[1] = data->byte;
1932 case I2C_SMBUS_WORD_DATA:
1933 if (read_write == I2C_SMBUS_READ)
1937 msgbuf0[1] = data->word & 0xff;
1938 msgbuf0[2] = data->word >> 8;
1941 case I2C_SMBUS_PROC_CALL:
1942 num = 2; /* Special case */
1943 read_write = I2C_SMBUS_READ;
1946 msgbuf0[1] = data->word & 0xff;
1947 msgbuf0[2] = data->word >> 8;
1949 case I2C_SMBUS_BLOCK_DATA:
1950 if (read_write == I2C_SMBUS_READ) {
1951 msg[1].flags |= I2C_M_RECV_LEN;
1952 msg[1].len = 1; /* block length will be added by
1953 the underlying bus driver */
1955 msg[0].len = data->block[0] + 2;
1956 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
1957 dev_err(&adapter->dev,
1958 "Invalid block write size %d\n",
1962 for (i = 1; i < msg[0].len; i++)
1963 msgbuf0[i] = data->block[i-1];
1966 case I2C_SMBUS_BLOCK_PROC_CALL:
1967 num = 2; /* Another special case */
1968 read_write = I2C_SMBUS_READ;
1969 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
1970 dev_err(&adapter->dev,
1971 "Invalid block write size %d\n",
1975 msg[0].len = data->block[0] + 2;
1976 for (i = 1; i < msg[0].len; i++)
1977 msgbuf0[i] = data->block[i-1];
1978 msg[1].flags |= I2C_M_RECV_LEN;
1979 msg[1].len = 1; /* block length will be added by
1980 the underlying bus driver */
1982 case I2C_SMBUS_I2C_BLOCK_DATA:
1983 if (read_write == I2C_SMBUS_READ) {
1984 msg[1].len = data->block[0];
1986 msg[0].len = data->block[0] + 1;
1987 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
1988 dev_err(&adapter->dev,
1989 "Invalid block write size %d\n",
1993 for (i = 1; i <= data->block[0]; i++)
1994 msgbuf0[i] = data->block[i];
1998 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
2002 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
2003 && size != I2C_SMBUS_I2C_BLOCK_DATA);
2005 /* Compute PEC if first message is a write */
2006 if (!(msg[0].flags & I2C_M_RD)) {
2007 if (num == 1) /* Write only */
2008 i2c_smbus_add_pec(&msg[0]);
2009 else /* Write followed by read */
2010 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
2012 /* Ask for PEC if last message is a read */
2013 if (msg[num-1].flags & I2C_M_RD)
2017 status = i2c_transfer(adapter, msg, num);
2021 /* Check PEC if last message is a read */
2022 if (i && (msg[num-1].flags & I2C_M_RD)) {
2023 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
2028 if (read_write == I2C_SMBUS_READ)
2030 case I2C_SMBUS_BYTE:
2031 data->byte = msgbuf0[0];
2033 case I2C_SMBUS_BYTE_DATA:
2034 data->byte = msgbuf1[0];
2036 case I2C_SMBUS_WORD_DATA:
2037 case I2C_SMBUS_PROC_CALL:
2038 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
2040 case I2C_SMBUS_I2C_BLOCK_DATA:
2041 for (i = 0; i < data->block[0]; i++)
2042 data->block[i+1] = msgbuf1[i];
2044 case I2C_SMBUS_BLOCK_DATA:
2045 case I2C_SMBUS_BLOCK_PROC_CALL:
2046 for (i = 0; i < msgbuf1[0] + 1; i++)
2047 data->block[i] = msgbuf1[i];
2054 * i2c_smbus_xfer - execute SMBus protocol operations
2055 * @adapter: Handle to I2C bus
2056 * @addr: Address of SMBus slave on that bus
2057 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
2058 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
2059 * @command: Byte interpreted by slave, for protocols which use such bytes
2060 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
2061 * @data: Data to be read or written
2063 * This executes an SMBus protocol operation, and returns a negative
2064 * errno code else zero on success.
2066 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
2067 char read_write, u8 command, int protocol,
2068 union i2c_smbus_data *data)
2070 unsigned long orig_jiffies;
2074 flags &= I2C_M_TEN | I2C_CLIENT_PEC;
2076 if (adapter->algo->smbus_xfer) {
2077 i2c_lock_adapter(adapter);
2079 /* Retry automatically on arbitration loss */
2080 orig_jiffies = jiffies;
2081 for (res = 0, try = 0; try <= adapter->retries; try++) {
2082 res = adapter->algo->smbus_xfer(adapter, addr, flags,
2083 read_write, command,
2087 if (time_after(jiffies,
2088 orig_jiffies + adapter->timeout))
2091 i2c_unlock_adapter(adapter);
2093 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
2094 command, protocol, data);
2098 EXPORT_SYMBOL(i2c_smbus_xfer);
2100 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2101 MODULE_DESCRIPTION("I2C-Bus main module");
2102 MODULE_LICENSE("GPL");