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 return pm_generic_suspend(dev);
202 return i2c_legacy_suspend(dev, PMSG_SUSPEND);
205 static int i2c_device_pm_resume(struct device *dev)
207 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
210 return pm_generic_resume(dev);
212 return i2c_legacy_resume(dev);
215 static int i2c_device_pm_freeze(struct device *dev)
217 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
220 return pm_generic_freeze(dev);
222 return i2c_legacy_suspend(dev, PMSG_FREEZE);
225 static int i2c_device_pm_thaw(struct device *dev)
227 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
230 return pm_generic_thaw(dev);
232 return i2c_legacy_resume(dev);
235 static int i2c_device_pm_poweroff(struct device *dev)
237 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
240 return pm_generic_poweroff(dev);
242 return i2c_legacy_suspend(dev, PMSG_HIBERNATE);
245 static int i2c_device_pm_restore(struct device *dev)
247 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
250 return pm_generic_restore(dev);
252 return i2c_legacy_resume(dev);
254 #else /* !CONFIG_PM_SLEEP */
255 #define i2c_device_pm_suspend NULL
256 #define i2c_device_pm_resume NULL
257 #define i2c_device_pm_freeze NULL
258 #define i2c_device_pm_thaw NULL
259 #define i2c_device_pm_poweroff NULL
260 #define i2c_device_pm_restore NULL
261 #endif /* !CONFIG_PM_SLEEP */
263 static void i2c_client_dev_release(struct device *dev)
265 kfree(to_i2c_client(dev));
269 show_name(struct device *dev, struct device_attribute *attr, char *buf)
271 return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
272 to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
276 show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
278 struct i2c_client *client = to_i2c_client(dev);
279 return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
282 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
283 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
285 static struct attribute *i2c_dev_attrs[] = {
287 /* modalias helps coldplug: modprobe $(cat .../modalias) */
288 &dev_attr_modalias.attr,
292 static struct attribute_group i2c_dev_attr_group = {
293 .attrs = i2c_dev_attrs,
296 static const struct attribute_group *i2c_dev_attr_groups[] = {
301 static const struct dev_pm_ops i2c_device_pm_ops = {
302 .suspend = i2c_device_pm_suspend,
303 .resume = i2c_device_pm_resume,
304 .freeze = i2c_device_pm_freeze,
305 .thaw = i2c_device_pm_thaw,
306 .poweroff = i2c_device_pm_poweroff,
307 .restore = i2c_device_pm_restore,
309 pm_generic_runtime_suspend,
310 pm_generic_runtime_resume,
311 pm_generic_runtime_idle
315 struct bus_type i2c_bus_type = {
317 .match = i2c_device_match,
318 .probe = i2c_device_probe,
319 .remove = i2c_device_remove,
320 .shutdown = i2c_device_shutdown,
321 .pm = &i2c_device_pm_ops,
323 EXPORT_SYMBOL_GPL(i2c_bus_type);
325 static struct device_type i2c_client_type = {
326 .groups = i2c_dev_attr_groups,
327 .uevent = i2c_device_uevent,
328 .release = i2c_client_dev_release,
333 * i2c_verify_client - return parameter as i2c_client, or NULL
334 * @dev: device, probably from some driver model iterator
336 * When traversing the driver model tree, perhaps using driver model
337 * iterators like @device_for_each_child(), you can't assume very much
338 * about the nodes you find. Use this function to avoid oopses caused
339 * by wrongly treating some non-I2C device as an i2c_client.
341 struct i2c_client *i2c_verify_client(struct device *dev)
343 return (dev->type == &i2c_client_type)
347 EXPORT_SYMBOL(i2c_verify_client);
350 /* This is a permissive address validity check, I2C address map constraints
351 * are purposedly not enforced, except for the general call address. */
352 static int i2c_check_client_addr_validity(const struct i2c_client *client)
354 if (client->flags & I2C_CLIENT_TEN) {
355 /* 10-bit address, all values are valid */
356 if (client->addr > 0x3ff)
359 /* 7-bit address, reject the general call address */
360 if (client->addr == 0x00 || client->addr > 0x7f)
366 /* And this is a strict address validity check, used when probing. If a
367 * device uses a reserved address, then it shouldn't be probed. 7-bit
368 * addressing is assumed, 10-bit address devices are rare and should be
369 * explicitly enumerated. */
370 static int i2c_check_addr_validity(unsigned short addr)
373 * Reserved addresses per I2C specification:
374 * 0x00 General call address / START byte
376 * 0x02 Reserved for different bus format
377 * 0x03 Reserved for future purposes
378 * 0x04-0x07 Hs-mode master code
379 * 0x78-0x7b 10-bit slave addressing
380 * 0x7c-0x7f Reserved for future purposes
382 if (addr < 0x08 || addr > 0x77)
387 static int __i2c_check_addr_busy(struct device *dev, void *addrp)
389 struct i2c_client *client = i2c_verify_client(dev);
390 int addr = *(int *)addrp;
392 if (client && client->addr == addr)
397 /* walk up mux tree */
398 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
400 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
403 result = device_for_each_child(&adapter->dev, &addr,
404 __i2c_check_addr_busy);
406 if (!result && parent)
407 result = i2c_check_mux_parents(parent, addr);
412 /* recurse down mux tree */
413 static int i2c_check_mux_children(struct device *dev, void *addrp)
417 if (dev->type == &i2c_adapter_type)
418 result = device_for_each_child(dev, addrp,
419 i2c_check_mux_children);
421 result = __i2c_check_addr_busy(dev, addrp);
426 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
428 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
432 result = i2c_check_mux_parents(parent, addr);
435 result = device_for_each_child(&adapter->dev, &addr,
436 i2c_check_mux_children);
442 * i2c_lock_adapter - Get exclusive access to an I2C bus segment
443 * @adapter: Target I2C bus segment
445 void i2c_lock_adapter(struct i2c_adapter *adapter)
447 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
450 i2c_lock_adapter(parent);
452 rt_mutex_lock(&adapter->bus_lock);
454 EXPORT_SYMBOL_GPL(i2c_lock_adapter);
457 * i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment
458 * @adapter: Target I2C bus segment
460 static int i2c_trylock_adapter(struct i2c_adapter *adapter)
462 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
465 return i2c_trylock_adapter(parent);
467 return rt_mutex_trylock(&adapter->bus_lock);
471 * i2c_unlock_adapter - Release exclusive access to an I2C bus segment
472 * @adapter: Target I2C bus segment
474 void i2c_unlock_adapter(struct i2c_adapter *adapter)
476 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
479 i2c_unlock_adapter(parent);
481 rt_mutex_unlock(&adapter->bus_lock);
483 EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
486 * i2c_new_device - instantiate an i2c device
487 * @adap: the adapter managing the device
488 * @info: describes one I2C device; bus_num is ignored
491 * Create an i2c device. Binding is handled through driver model
492 * probe()/remove() methods. A driver may be bound to this device when we
493 * return from this function, or any later moment (e.g. maybe hotplugging will
494 * load the driver module). This call is not appropriate for use by mainboard
495 * initialization logic, which usually runs during an arch_initcall() long
496 * before any i2c_adapter could exist.
498 * This returns the new i2c client, which may be saved for later use with
499 * i2c_unregister_device(); or NULL to indicate an error.
502 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
504 struct i2c_client *client;
507 client = kzalloc(sizeof *client, GFP_KERNEL);
511 client->adapter = adap;
513 client->dev.platform_data = info->platform_data;
516 client->dev.archdata = *info->archdata;
518 client->flags = info->flags;
519 client->addr = info->addr;
520 client->irq = info->irq;
522 strlcpy(client->name, info->type, sizeof(client->name));
524 /* Check for address validity */
525 status = i2c_check_client_addr_validity(client);
527 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
528 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
532 /* Check for address business */
533 status = i2c_check_addr_busy(adap, client->addr);
537 client->dev.parent = &client->adapter->dev;
538 client->dev.bus = &i2c_bus_type;
539 client->dev.type = &i2c_client_type;
541 client->dev.of_node = info->of_node;
544 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
546 status = device_register(&client->dev);
550 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
551 client->name, dev_name(&client->dev));
556 dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
557 "(%d)\n", client->name, client->addr, status);
562 EXPORT_SYMBOL_GPL(i2c_new_device);
566 * i2c_unregister_device - reverse effect of i2c_new_device()
567 * @client: value returned from i2c_new_device()
570 void i2c_unregister_device(struct i2c_client *client)
572 device_unregister(&client->dev);
574 EXPORT_SYMBOL_GPL(i2c_unregister_device);
577 static const struct i2c_device_id dummy_id[] = {
582 static int dummy_probe(struct i2c_client *client,
583 const struct i2c_device_id *id)
588 static int dummy_remove(struct i2c_client *client)
593 static struct i2c_driver dummy_driver = {
594 .driver.name = "dummy",
595 .probe = dummy_probe,
596 .remove = dummy_remove,
597 .id_table = dummy_id,
601 * i2c_new_dummy - return a new i2c device bound to a dummy driver
602 * @adapter: the adapter managing the device
603 * @address: seven bit address to be used
606 * This returns an I2C client bound to the "dummy" driver, intended for use
607 * with devices that consume multiple addresses. Examples of such chips
608 * include various EEPROMS (like 24c04 and 24c08 models).
610 * These dummy devices have two main uses. First, most I2C and SMBus calls
611 * except i2c_transfer() need a client handle; the dummy will be that handle.
612 * And second, this prevents the specified address from being bound to a
615 * This returns the new i2c client, which should be saved for later use with
616 * i2c_unregister_device(); or NULL to indicate an error.
618 struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
620 struct i2c_board_info info = {
621 I2C_BOARD_INFO("dummy", address),
624 return i2c_new_device(adapter, &info);
626 EXPORT_SYMBOL_GPL(i2c_new_dummy);
628 /* ------------------------------------------------------------------------- */
630 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
632 static void i2c_adapter_dev_release(struct device *dev)
634 struct i2c_adapter *adap = to_i2c_adapter(dev);
635 complete(&adap->dev_released);
639 * Let users instantiate I2C devices through sysfs. This can be used when
640 * platform initialization code doesn't contain the proper data for
641 * whatever reason. Also useful for drivers that do device detection and
642 * detection fails, either because the device uses an unexpected address,
643 * or this is a compatible device with different ID register values.
645 * Parameter checking may look overzealous, but we really don't want
646 * the user to provide incorrect parameters.
649 i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
650 const char *buf, size_t count)
652 struct i2c_adapter *adap = to_i2c_adapter(dev);
653 struct i2c_board_info info;
654 struct i2c_client *client;
658 memset(&info, 0, sizeof(struct i2c_board_info));
660 blank = strchr(buf, ' ');
662 dev_err(dev, "%s: Missing parameters\n", "new_device");
665 if (blank - buf > I2C_NAME_SIZE - 1) {
666 dev_err(dev, "%s: Invalid device name\n", "new_device");
669 memcpy(info.type, buf, blank - buf);
671 /* Parse remaining parameters, reject extra parameters */
672 res = sscanf(++blank, "%hi%c", &info.addr, &end);
674 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
677 if (res > 1 && end != '\n') {
678 dev_err(dev, "%s: Extra parameters\n", "new_device");
682 client = i2c_new_device(adap, &info);
686 /* Keep track of the added device */
687 mutex_lock(&adap->userspace_clients_lock);
688 list_add_tail(&client->detected, &adap->userspace_clients);
689 mutex_unlock(&adap->userspace_clients_lock);
690 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
691 info.type, info.addr);
697 * And of course let the users delete the devices they instantiated, if
698 * they got it wrong. This interface can only be used to delete devices
699 * instantiated by i2c_sysfs_new_device above. This guarantees that we
700 * don't delete devices to which some kernel code still has references.
702 * Parameter checking may look overzealous, but we really don't want
703 * the user to delete the wrong device.
706 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
707 const char *buf, size_t count)
709 struct i2c_adapter *adap = to_i2c_adapter(dev);
710 struct i2c_client *client, *next;
715 /* Parse parameters, reject extra parameters */
716 res = sscanf(buf, "%hi%c", &addr, &end);
718 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
721 if (res > 1 && end != '\n') {
722 dev_err(dev, "%s: Extra parameters\n", "delete_device");
726 /* Make sure the device was added through sysfs */
728 mutex_lock(&adap->userspace_clients_lock);
729 list_for_each_entry_safe(client, next, &adap->userspace_clients,
731 if (client->addr == addr) {
732 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
733 "delete_device", client->name, client->addr);
735 list_del(&client->detected);
736 i2c_unregister_device(client);
741 mutex_unlock(&adap->userspace_clients_lock);
744 dev_err(dev, "%s: Can't find device in list\n",
749 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
750 static DEVICE_ATTR(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device);
752 static struct attribute *i2c_adapter_attrs[] = {
754 &dev_attr_new_device.attr,
755 &dev_attr_delete_device.attr,
759 static struct attribute_group i2c_adapter_attr_group = {
760 .attrs = i2c_adapter_attrs,
763 static const struct attribute_group *i2c_adapter_attr_groups[] = {
764 &i2c_adapter_attr_group,
768 struct device_type i2c_adapter_type = {
769 .groups = i2c_adapter_attr_groups,
770 .release = i2c_adapter_dev_release,
772 EXPORT_SYMBOL_GPL(i2c_adapter_type);
774 #ifdef CONFIG_I2C_COMPAT
775 static struct class_compat *i2c_adapter_compat_class;
778 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
780 struct i2c_devinfo *devinfo;
782 down_read(&__i2c_board_lock);
783 list_for_each_entry(devinfo, &__i2c_board_list, list) {
784 if (devinfo->busnum == adapter->nr
785 && !i2c_new_device(adapter,
786 &devinfo->board_info))
787 dev_err(&adapter->dev,
788 "Can't create device at 0x%02x\n",
789 devinfo->board_info.addr);
791 up_read(&__i2c_board_lock);
794 static int i2c_do_add_adapter(struct i2c_driver *driver,
795 struct i2c_adapter *adap)
797 /* Detect supported devices on that bus, and instantiate them */
798 i2c_detect(adap, driver);
800 /* Let legacy drivers scan this bus for matching devices */
801 if (driver->attach_adapter) {
802 /* We ignore the return code; if it fails, too bad */
803 driver->attach_adapter(adap);
808 static int __process_new_adapter(struct device_driver *d, void *data)
810 return i2c_do_add_adapter(to_i2c_driver(d), data);
813 static int i2c_register_adapter(struct i2c_adapter *adap)
817 /* Can't register until after driver model init */
818 if (unlikely(WARN_ON(!i2c_bus_type.p))) {
824 if (unlikely(adap->name[0] == '\0')) {
825 pr_err("i2c-core: Attempt to register an adapter with "
829 if (unlikely(!adap->algo)) {
830 pr_err("i2c-core: Attempt to register adapter '%s' with "
831 "no algo!\n", adap->name);
835 rt_mutex_init(&adap->bus_lock);
836 mutex_init(&adap->userspace_clients_lock);
837 INIT_LIST_HEAD(&adap->userspace_clients);
839 /* Set default timeout to 1 second if not already set */
840 if (adap->timeout == 0)
843 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
844 adap->dev.bus = &i2c_bus_type;
845 adap->dev.type = &i2c_adapter_type;
846 res = device_register(&adap->dev);
850 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
852 #ifdef CONFIG_I2C_COMPAT
853 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
857 "Failed to create compatibility class link\n");
860 /* create pre-declared device nodes */
861 if (adap->nr < __i2c_first_dynamic_bus_num)
862 i2c_scan_static_board_info(adap);
865 mutex_lock(&core_lock);
866 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
867 mutex_unlock(&core_lock);
872 mutex_lock(&core_lock);
873 idr_remove(&i2c_adapter_idr, adap->nr);
874 mutex_unlock(&core_lock);
879 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
880 * @adapter: the adapter to add
883 * This routine is used to declare an I2C adapter when its bus number
884 * doesn't matter. Examples: for I2C adapters dynamically added by
885 * USB links or PCI plugin cards.
887 * When this returns zero, a new bus number was allocated and stored
888 * in adap->nr, and the specified adapter became available for clients.
889 * Otherwise, a negative errno value is returned.
891 int i2c_add_adapter(struct i2c_adapter *adapter)
896 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
899 mutex_lock(&core_lock);
900 /* "above" here means "above or equal to", sigh */
901 res = idr_get_new_above(&i2c_adapter_idr, adapter,
902 __i2c_first_dynamic_bus_num, &id);
903 mutex_unlock(&core_lock);
912 return i2c_register_adapter(adapter);
914 EXPORT_SYMBOL(i2c_add_adapter);
917 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
918 * @adap: the adapter to register (with adap->nr initialized)
921 * This routine is used to declare an I2C adapter when its bus number
922 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
923 * or otherwise built in to the system's mainboard, and where i2c_board_info
924 * is used to properly configure I2C devices.
926 * If no devices have pre-been declared for this bus, then be sure to
927 * register the adapter before any dynamically allocated ones. Otherwise
928 * the required bus ID may not be available.
930 * When this returns zero, the specified adapter became available for
931 * clients using the bus number provided in adap->nr. Also, the table
932 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
933 * and the appropriate driver model device nodes are created. Otherwise, a
934 * negative errno value is returned.
936 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
941 if (adap->nr & ~MAX_ID_MASK)
945 if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
948 mutex_lock(&core_lock);
949 /* "above" here means "above or equal to", sigh;
950 * we need the "equal to" result to force the result
952 status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
953 if (status == 0 && id != adap->nr) {
955 idr_remove(&i2c_adapter_idr, id);
957 mutex_unlock(&core_lock);
958 if (status == -EAGAIN)
962 status = i2c_register_adapter(adap);
965 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
967 static int i2c_do_del_adapter(struct i2c_driver *driver,
968 struct i2c_adapter *adapter)
970 struct i2c_client *client, *_n;
973 /* Remove the devices we created ourselves as the result of hardware
974 * probing (using a driver's detect method) */
975 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
976 if (client->adapter == adapter) {
977 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
978 client->name, client->addr);
979 list_del(&client->detected);
980 i2c_unregister_device(client);
984 if (!driver->detach_adapter)
986 res = driver->detach_adapter(adapter);
988 dev_err(&adapter->dev, "detach_adapter failed (%d) "
989 "for driver [%s]\n", res, driver->driver.name);
993 static int __unregister_client(struct device *dev, void *dummy)
995 struct i2c_client *client = i2c_verify_client(dev);
996 if (client && strcmp(client->name, "dummy"))
997 i2c_unregister_device(client);
1001 static int __unregister_dummy(struct device *dev, void *dummy)
1003 struct i2c_client *client = i2c_verify_client(dev);
1005 i2c_unregister_device(client);
1009 static int __process_removed_adapter(struct device_driver *d, void *data)
1011 return i2c_do_del_adapter(to_i2c_driver(d), data);
1015 * i2c_del_adapter - unregister I2C adapter
1016 * @adap: the adapter being unregistered
1017 * Context: can sleep
1019 * This unregisters an I2C adapter which was previously registered
1020 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1022 int i2c_del_adapter(struct i2c_adapter *adap)
1025 struct i2c_adapter *found;
1026 struct i2c_client *client, *next;
1028 /* First make sure that this adapter was ever added */
1029 mutex_lock(&core_lock);
1030 found = idr_find(&i2c_adapter_idr, adap->nr);
1031 mutex_unlock(&core_lock);
1032 if (found != adap) {
1033 pr_debug("i2c-core: attempting to delete unregistered "
1034 "adapter [%s]\n", adap->name);
1038 /* Tell drivers about this removal */
1039 mutex_lock(&core_lock);
1040 res = bus_for_each_drv(&i2c_bus_type, NULL, adap,
1041 __process_removed_adapter);
1042 mutex_unlock(&core_lock);
1046 /* Remove devices instantiated from sysfs */
1047 mutex_lock(&adap->userspace_clients_lock);
1048 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1050 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1052 list_del(&client->detected);
1053 i2c_unregister_device(client);
1055 mutex_unlock(&adap->userspace_clients_lock);
1057 /* Detach any active clients. This can't fail, thus we do not
1058 * check the returned value. This is a two-pass process, because
1059 * we can't remove the dummy devices during the first pass: they
1060 * could have been instantiated by real devices wishing to clean
1061 * them up properly, so we give them a chance to do that first. */
1062 res = device_for_each_child(&adap->dev, NULL, __unregister_client);
1063 res = device_for_each_child(&adap->dev, NULL, __unregister_dummy);
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(const 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(const 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 /* Stop here if the classes do not match */
1508 if (!(adapter->class & driver->class))
1511 /* Set up a temporary client to help detect callback */
1512 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
1515 temp_client->adapter = adapter;
1517 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);
1530 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
1532 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1533 I2C_SMBUS_QUICK, NULL) >= 0;
1535 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
1538 i2c_new_probed_device(struct i2c_adapter *adap,
1539 struct i2c_board_info *info,
1540 unsigned short const *addr_list,
1541 int (*probe)(struct i2c_adapter *, unsigned short addr))
1546 probe = i2c_default_probe;
1548 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
1549 /* Check address validity */
1550 if (i2c_check_addr_validity(addr_list[i]) < 0) {
1551 dev_warn(&adap->dev, "Invalid 7-bit address "
1552 "0x%02x\n", addr_list[i]);
1556 /* Check address availability */
1557 if (i2c_check_addr_busy(adap, addr_list[i])) {
1558 dev_dbg(&adap->dev, "Address 0x%02x already in "
1559 "use, not probing\n", addr_list[i]);
1563 /* Test address responsiveness */
1564 if (probe(adap, addr_list[i]))
1568 if (addr_list[i] == I2C_CLIENT_END) {
1569 dev_dbg(&adap->dev, "Probing failed, no device found\n");
1573 info->addr = addr_list[i];
1574 return i2c_new_device(adap, info);
1576 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
1578 struct i2c_adapter *i2c_get_adapter(int id)
1580 struct i2c_adapter *adapter;
1582 mutex_lock(&core_lock);
1583 adapter = idr_find(&i2c_adapter_idr, id);
1584 if (adapter && !try_module_get(adapter->owner))
1587 mutex_unlock(&core_lock);
1590 EXPORT_SYMBOL(i2c_get_adapter);
1592 void i2c_put_adapter(struct i2c_adapter *adap)
1594 module_put(adap->owner);
1596 EXPORT_SYMBOL(i2c_put_adapter);
1598 /* The SMBus parts */
1600 #define POLY (0x1070U << 3)
1601 static u8 crc8(u16 data)
1605 for (i = 0; i < 8; i++) {
1610 return (u8)(data >> 8);
1613 /* Incremental CRC8 over count bytes in the array pointed to by p */
1614 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
1618 for (i = 0; i < count; i++)
1619 crc = crc8((crc ^ p[i]) << 8);
1623 /* Assume a 7-bit address, which is reasonable for SMBus */
1624 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
1626 /* The address will be sent first */
1627 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
1628 pec = i2c_smbus_pec(pec, &addr, 1);
1630 /* The data buffer follows */
1631 return i2c_smbus_pec(pec, msg->buf, msg->len);
1634 /* Used for write only transactions */
1635 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
1637 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
1641 /* Return <0 on CRC error
1642 If there was a write before this read (most cases) we need to take the
1643 partial CRC from the write part into account.
1644 Note that this function does modify the message (we need to decrease the
1645 message length to hide the CRC byte from the caller). */
1646 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
1648 u8 rpec = msg->buf[--msg->len];
1649 cpec = i2c_smbus_msg_pec(cpec, msg);
1652 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
1660 * i2c_smbus_read_byte - SMBus "receive byte" protocol
1661 * @client: Handle to slave device
1663 * This executes the SMBus "receive byte" protocol, returning negative errno
1664 * else the byte received from the device.
1666 s32 i2c_smbus_read_byte(const struct i2c_client *client)
1668 union i2c_smbus_data data;
1671 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1673 I2C_SMBUS_BYTE, &data);
1674 return (status < 0) ? status : data.byte;
1676 EXPORT_SYMBOL(i2c_smbus_read_byte);
1679 * i2c_smbus_write_byte - SMBus "send byte" protocol
1680 * @client: Handle to slave device
1681 * @value: Byte to be sent
1683 * This executes the SMBus "send byte" protocol, returning negative errno
1684 * else zero on success.
1686 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
1688 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1689 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
1691 EXPORT_SYMBOL(i2c_smbus_write_byte);
1694 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
1695 * @client: Handle to slave device
1696 * @command: Byte interpreted by slave
1698 * This executes the SMBus "read byte" protocol, returning negative errno
1699 * else a data byte received from the device.
1701 s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
1703 union i2c_smbus_data data;
1706 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1707 I2C_SMBUS_READ, command,
1708 I2C_SMBUS_BYTE_DATA, &data);
1709 return (status < 0) ? status : data.byte;
1711 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
1714 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
1715 * @client: Handle to slave device
1716 * @command: Byte interpreted by slave
1717 * @value: Byte being written
1719 * This executes the SMBus "write byte" protocol, returning negative errno
1720 * else zero on success.
1722 s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
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(const 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(const struct i2c_client *client, u8 command,
1765 union i2c_smbus_data data;
1767 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1768 I2C_SMBUS_WRITE, command,
1769 I2C_SMBUS_WORD_DATA, &data);
1771 EXPORT_SYMBOL(i2c_smbus_write_word_data);
1774 * i2c_smbus_process_call - SMBus "process call" protocol
1775 * @client: Handle to slave device
1776 * @command: Byte interpreted by slave
1777 * @value: 16-bit "word" being written
1779 * This executes the SMBus "process call" protocol, returning negative errno
1780 * else a 16-bit unsigned "word" received from the device.
1782 s32 i2c_smbus_process_call(const struct i2c_client *client, u8 command,
1785 union i2c_smbus_data data;
1789 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1790 I2C_SMBUS_WRITE, command,
1791 I2C_SMBUS_PROC_CALL, &data);
1792 return (status < 0) ? status : data.word;
1794 EXPORT_SYMBOL(i2c_smbus_process_call);
1797 * i2c_smbus_read_block_data - SMBus "block read" protocol
1798 * @client: Handle to slave device
1799 * @command: Byte interpreted by slave
1800 * @values: Byte array into which data will be read; big enough to hold
1801 * the data returned by the slave. SMBus allows at most 32 bytes.
1803 * This executes the SMBus "block read" protocol, returning negative errno
1804 * else the number of data bytes in the slave's response.
1806 * Note that using this function requires that the client's adapter support
1807 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
1808 * support this; its emulation through I2C messaging relies on a specific
1809 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
1811 s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
1814 union i2c_smbus_data data;
1817 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1818 I2C_SMBUS_READ, command,
1819 I2C_SMBUS_BLOCK_DATA, &data);
1823 memcpy(values, &data.block[1], data.block[0]);
1824 return data.block[0];
1826 EXPORT_SYMBOL(i2c_smbus_read_block_data);
1829 * i2c_smbus_write_block_data - SMBus "block write" protocol
1830 * @client: Handle to slave device
1831 * @command: Byte interpreted by slave
1832 * @length: Size of data block; SMBus allows at most 32 bytes
1833 * @values: Byte array which will be written.
1835 * This executes the SMBus "block write" protocol, returning negative errno
1836 * else zero on success.
1838 s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
1839 u8 length, const u8 *values)
1841 union i2c_smbus_data data;
1843 if (length > I2C_SMBUS_BLOCK_MAX)
1844 length = I2C_SMBUS_BLOCK_MAX;
1845 data.block[0] = length;
1846 memcpy(&data.block[1], values, length);
1847 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1848 I2C_SMBUS_WRITE, command,
1849 I2C_SMBUS_BLOCK_DATA, &data);
1851 EXPORT_SYMBOL(i2c_smbus_write_block_data);
1853 /* Returns the number of read bytes */
1854 s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
1855 u8 length, u8 *values)
1857 union i2c_smbus_data data;
1860 if (length > I2C_SMBUS_BLOCK_MAX)
1861 length = I2C_SMBUS_BLOCK_MAX;
1862 data.block[0] = length;
1863 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1864 I2C_SMBUS_READ, command,
1865 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1869 memcpy(values, &data.block[1], data.block[0]);
1870 return data.block[0];
1872 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
1874 s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
1875 u8 length, const u8 *values)
1877 union i2c_smbus_data data;
1879 if (length > I2C_SMBUS_BLOCK_MAX)
1880 length = I2C_SMBUS_BLOCK_MAX;
1881 data.block[0] = length;
1882 memcpy(data.block + 1, values, length);
1883 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1884 I2C_SMBUS_WRITE, command,
1885 I2C_SMBUS_I2C_BLOCK_DATA, &data);
1887 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
1889 /* Simulate a SMBus command using the i2c protocol
1890 No checking of parameters is done! */
1891 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
1892 unsigned short flags,
1893 char read_write, u8 command, int size,
1894 union i2c_smbus_data *data)
1896 /* So we need to generate a series of msgs. In the case of writing, we
1897 need to use only one message; when reading, we need two. We initialize
1898 most things with sane defaults, to keep the code below somewhat
1900 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
1901 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
1902 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
1903 struct i2c_msg msg[2] = { { addr, flags, 1, msgbuf0 },
1904 { addr, flags | I2C_M_RD, 0, msgbuf1 }
1910 msgbuf0[0] = command;
1912 case I2C_SMBUS_QUICK:
1914 /* Special case: The read/write field is used as data */
1915 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
1919 case I2C_SMBUS_BYTE:
1920 if (read_write == I2C_SMBUS_READ) {
1921 /* Special case: only a read! */
1922 msg[0].flags = I2C_M_RD | flags;
1926 case I2C_SMBUS_BYTE_DATA:
1927 if (read_write == I2C_SMBUS_READ)
1931 msgbuf0[1] = data->byte;
1934 case I2C_SMBUS_WORD_DATA:
1935 if (read_write == I2C_SMBUS_READ)
1939 msgbuf0[1] = data->word & 0xff;
1940 msgbuf0[2] = data->word >> 8;
1943 case I2C_SMBUS_PROC_CALL:
1944 num = 2; /* Special case */
1945 read_write = I2C_SMBUS_READ;
1948 msgbuf0[1] = data->word & 0xff;
1949 msgbuf0[2] = data->word >> 8;
1951 case I2C_SMBUS_BLOCK_DATA:
1952 if (read_write == I2C_SMBUS_READ) {
1953 msg[1].flags |= I2C_M_RECV_LEN;
1954 msg[1].len = 1; /* block length will be added by
1955 the underlying bus driver */
1957 msg[0].len = data->block[0] + 2;
1958 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
1959 dev_err(&adapter->dev,
1960 "Invalid block write size %d\n",
1964 for (i = 1; i < msg[0].len; i++)
1965 msgbuf0[i] = data->block[i-1];
1968 case I2C_SMBUS_BLOCK_PROC_CALL:
1969 num = 2; /* Another special case */
1970 read_write = I2C_SMBUS_READ;
1971 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
1972 dev_err(&adapter->dev,
1973 "Invalid block write size %d\n",
1977 msg[0].len = data->block[0] + 2;
1978 for (i = 1; i < msg[0].len; i++)
1979 msgbuf0[i] = data->block[i-1];
1980 msg[1].flags |= I2C_M_RECV_LEN;
1981 msg[1].len = 1; /* block length will be added by
1982 the underlying bus driver */
1984 case I2C_SMBUS_I2C_BLOCK_DATA:
1985 if (read_write == I2C_SMBUS_READ) {
1986 msg[1].len = data->block[0];
1988 msg[0].len = data->block[0] + 1;
1989 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
1990 dev_err(&adapter->dev,
1991 "Invalid block write size %d\n",
1995 for (i = 1; i <= data->block[0]; i++)
1996 msgbuf0[i] = data->block[i];
2000 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
2004 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
2005 && size != I2C_SMBUS_I2C_BLOCK_DATA);
2007 /* Compute PEC if first message is a write */
2008 if (!(msg[0].flags & I2C_M_RD)) {
2009 if (num == 1) /* Write only */
2010 i2c_smbus_add_pec(&msg[0]);
2011 else /* Write followed by read */
2012 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
2014 /* Ask for PEC if last message is a read */
2015 if (msg[num-1].flags & I2C_M_RD)
2019 status = i2c_transfer(adapter, msg, num);
2023 /* Check PEC if last message is a read */
2024 if (i && (msg[num-1].flags & I2C_M_RD)) {
2025 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
2030 if (read_write == I2C_SMBUS_READ)
2032 case I2C_SMBUS_BYTE:
2033 data->byte = msgbuf0[0];
2035 case I2C_SMBUS_BYTE_DATA:
2036 data->byte = msgbuf1[0];
2038 case I2C_SMBUS_WORD_DATA:
2039 case I2C_SMBUS_PROC_CALL:
2040 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
2042 case I2C_SMBUS_I2C_BLOCK_DATA:
2043 for (i = 0; i < data->block[0]; i++)
2044 data->block[i+1] = msgbuf1[i];
2046 case I2C_SMBUS_BLOCK_DATA:
2047 case I2C_SMBUS_BLOCK_PROC_CALL:
2048 for (i = 0; i < msgbuf1[0] + 1; i++)
2049 data->block[i] = msgbuf1[i];
2056 * i2c_smbus_xfer - execute SMBus protocol operations
2057 * @adapter: Handle to I2C bus
2058 * @addr: Address of SMBus slave on that bus
2059 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
2060 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
2061 * @command: Byte interpreted by slave, for protocols which use such bytes
2062 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
2063 * @data: Data to be read or written
2065 * This executes an SMBus protocol operation, and returns a negative
2066 * errno code else zero on success.
2068 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
2069 char read_write, u8 command, int protocol,
2070 union i2c_smbus_data *data)
2072 unsigned long orig_jiffies;
2076 flags &= I2C_M_TEN | I2C_CLIENT_PEC;
2078 if (adapter->algo->smbus_xfer) {
2079 i2c_lock_adapter(adapter);
2081 /* Retry automatically on arbitration loss */
2082 orig_jiffies = jiffies;
2083 for (res = 0, try = 0; try <= adapter->retries; try++) {
2084 res = adapter->algo->smbus_xfer(adapter, addr, flags,
2085 read_write, command,
2089 if (time_after(jiffies,
2090 orig_jiffies + adapter->timeout))
2093 i2c_unlock_adapter(adapter);
2095 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
2096 command, protocol, data);
2100 EXPORT_SYMBOL(i2c_smbus_xfer);
2102 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2103 MODULE_DESCRIPTION("I2C-Bus main module");
2104 MODULE_LICENSE("GPL");