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., 51 Franklin Street, Fifth Floor, Boston,
19 /* ------------------------------------------------------------------------- */
21 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
22 All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
23 SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
24 Jean Delvare <khali@linux-fr.org>
25 Mux support by Rodolfo Giometti <giometti@enneenne.com> and
26 Michael Lawnick <michael.lawnick.ext@nsn.com>
27 OF support is copyright (c) 2008 Jochen Friedrich <jochen@scram.de>
28 (based on a previous patch from Jon Smirl <jonsmirl@gmail.com>) and
29 (c) 2013 Wolfram Sang <wsa@the-dreams.de>
32 #include <linux/module.h>
33 #include <linux/kernel.h>
34 #include <linux/delay.h>
35 #include <linux/errno.h>
36 #include <linux/gpio.h>
37 #include <linux/slab.h>
38 #include <linux/i2c.h>
39 #include <linux/init.h>
40 #include <linux/idr.h>
41 #include <linux/mutex.h>
43 #include <linux/of_device.h>
44 #include <linux/of_irq.h>
45 #include <linux/completion.h>
46 #include <linux/hardirq.h>
47 #include <linux/irqflags.h>
48 #include <linux/rwsem.h>
49 #include <linux/pm_runtime.h>
50 #include <linux/acpi.h>
51 #include <asm/uaccess.h>
56 /* core_lock protects i2c_adapter_idr, and guarantees
57 that device detection, deletion of detected devices, and attach_adapter
58 calls are serialized */
59 static DEFINE_MUTEX(core_lock);
60 static DEFINE_IDR(i2c_adapter_idr);
62 static struct device_type i2c_client_type;
63 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
65 /* ------------------------------------------------------------------------- */
67 static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
68 const struct i2c_client *client)
71 if (strcmp(client->name, id->name) == 0)
78 static int i2c_device_match(struct device *dev, struct device_driver *drv)
80 struct i2c_client *client = i2c_verify_client(dev);
81 struct i2c_driver *driver;
86 /* Attempt an OF style match */
87 if (of_driver_match_device(dev, drv))
90 /* Then ACPI style match */
91 if (acpi_driver_match_device(dev, drv))
94 driver = to_i2c_driver(drv);
95 /* match on an id table if there is one */
97 return i2c_match_id(driver->id_table, client) != NULL;
103 /* uevent helps with hotplug: modprobe -q $(MODALIAS) */
104 static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
106 struct i2c_client *client = to_i2c_client(dev);
108 if (add_uevent_var(env, "MODALIAS=%s%s",
109 I2C_MODULE_PREFIX, client->name))
111 dev_dbg(dev, "uevent\n");
115 /* i2c bus recovery routines */
116 static int get_scl_gpio_value(struct i2c_adapter *adap)
118 return gpio_get_value(adap->bus_recovery_info->scl_gpio);
121 static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
123 gpio_set_value(adap->bus_recovery_info->scl_gpio, val);
126 static int get_sda_gpio_value(struct i2c_adapter *adap)
128 return gpio_get_value(adap->bus_recovery_info->sda_gpio);
131 static int i2c_get_gpios_for_recovery(struct i2c_adapter *adap)
133 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
134 struct device *dev = &adap->dev;
137 ret = gpio_request_one(bri->scl_gpio, GPIOF_OPEN_DRAIN |
138 GPIOF_OUT_INIT_HIGH, "i2c-scl");
140 dev_warn(dev, "Can't get SCL gpio: %d\n", bri->scl_gpio);
145 if (gpio_request_one(bri->sda_gpio, GPIOF_IN, "i2c-sda")) {
146 /* work without SDA polling */
147 dev_warn(dev, "Can't get SDA gpio: %d. Not using SDA polling\n",
156 static void i2c_put_gpios_for_recovery(struct i2c_adapter *adap)
158 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
161 gpio_free(bri->sda_gpio);
163 gpio_free(bri->scl_gpio);
167 * We are generating clock pulses. ndelay() determines durating of clk pulses.
168 * We will generate clock with rate 100 KHz and so duration of both clock levels
169 * is: delay in ns = (10^6 / 100) / 2
171 #define RECOVERY_NDELAY 5000
172 #define RECOVERY_CLK_CNT 9
174 static int i2c_generic_recovery(struct i2c_adapter *adap)
176 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
177 int i = 0, val = 1, ret = 0;
179 if (bri->prepare_recovery)
180 bri->prepare_recovery(bri);
183 * By this time SCL is high, as we need to give 9 falling-rising edges
185 while (i++ < RECOVERY_CLK_CNT * 2) {
187 /* Break if SDA is high */
188 if (bri->get_sda && bri->get_sda(adap))
190 /* SCL shouldn't be low here */
191 if (!bri->get_scl(adap)) {
193 "SCL is stuck low, exit recovery\n");
200 bri->set_scl(adap, val);
201 ndelay(RECOVERY_NDELAY);
204 if (bri->unprepare_recovery)
205 bri->unprepare_recovery(bri);
210 int i2c_generic_scl_recovery(struct i2c_adapter *adap)
212 adap->bus_recovery_info->set_scl(adap, 1);
213 return i2c_generic_recovery(adap);
216 int i2c_generic_gpio_recovery(struct i2c_adapter *adap)
220 ret = i2c_get_gpios_for_recovery(adap);
224 ret = i2c_generic_recovery(adap);
225 i2c_put_gpios_for_recovery(adap);
230 int i2c_recover_bus(struct i2c_adapter *adap)
232 if (!adap->bus_recovery_info)
235 dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
236 return adap->bus_recovery_info->recover_bus(adap);
239 static int i2c_device_probe(struct device *dev)
241 struct i2c_client *client = i2c_verify_client(dev);
242 struct i2c_driver *driver;
248 driver = to_i2c_driver(dev->driver);
249 if (!driver->probe || !driver->id_table)
252 if (!device_can_wakeup(&client->dev))
253 device_init_wakeup(&client->dev,
254 client->flags & I2C_CLIENT_WAKE);
255 dev_dbg(dev, "probe\n");
257 status = driver->probe(client, i2c_match_id(driver->id_table, client));
259 i2c_set_clientdata(client, NULL);
264 static int i2c_device_remove(struct device *dev)
266 struct i2c_client *client = i2c_verify_client(dev);
267 struct i2c_driver *driver;
270 if (!client || !dev->driver)
273 driver = to_i2c_driver(dev->driver);
274 if (driver->remove) {
275 dev_dbg(dev, "remove\n");
276 status = driver->remove(client);
282 i2c_set_clientdata(client, NULL);
287 static void i2c_device_shutdown(struct device *dev)
289 struct i2c_client *client = i2c_verify_client(dev);
290 struct i2c_driver *driver;
292 if (!client || !dev->driver)
294 driver = to_i2c_driver(dev->driver);
295 if (driver->shutdown)
296 driver->shutdown(client);
299 #ifdef CONFIG_PM_SLEEP
300 static int i2c_legacy_suspend(struct device *dev, pm_message_t mesg)
302 struct i2c_client *client = i2c_verify_client(dev);
303 struct i2c_driver *driver;
305 if (!client || !dev->driver)
307 driver = to_i2c_driver(dev->driver);
308 if (!driver->suspend)
310 return driver->suspend(client, mesg);
313 static int i2c_legacy_resume(struct device *dev)
315 struct i2c_client *client = i2c_verify_client(dev);
316 struct i2c_driver *driver;
318 if (!client || !dev->driver)
320 driver = to_i2c_driver(dev->driver);
323 return driver->resume(client);
326 static int i2c_device_pm_suspend(struct device *dev)
328 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
331 return pm_generic_suspend(dev);
333 return i2c_legacy_suspend(dev, PMSG_SUSPEND);
336 static int i2c_device_pm_resume(struct device *dev)
338 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
341 return pm_generic_resume(dev);
343 return i2c_legacy_resume(dev);
346 static int i2c_device_pm_freeze(struct device *dev)
348 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
351 return pm_generic_freeze(dev);
353 return i2c_legacy_suspend(dev, PMSG_FREEZE);
356 static int i2c_device_pm_thaw(struct device *dev)
358 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
361 return pm_generic_thaw(dev);
363 return i2c_legacy_resume(dev);
366 static int i2c_device_pm_poweroff(struct device *dev)
368 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
371 return pm_generic_poweroff(dev);
373 return i2c_legacy_suspend(dev, PMSG_HIBERNATE);
376 static int i2c_device_pm_restore(struct device *dev)
378 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
381 return pm_generic_restore(dev);
383 return i2c_legacy_resume(dev);
385 #else /* !CONFIG_PM_SLEEP */
386 #define i2c_device_pm_suspend NULL
387 #define i2c_device_pm_resume NULL
388 #define i2c_device_pm_freeze NULL
389 #define i2c_device_pm_thaw NULL
390 #define i2c_device_pm_poweroff NULL
391 #define i2c_device_pm_restore NULL
392 #endif /* !CONFIG_PM_SLEEP */
394 static void i2c_client_dev_release(struct device *dev)
396 kfree(to_i2c_client(dev));
400 show_name(struct device *dev, struct device_attribute *attr, char *buf)
402 return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
403 to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
407 show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
409 struct i2c_client *client = to_i2c_client(dev);
410 return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
413 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
414 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
416 static struct attribute *i2c_dev_attrs[] = {
418 /* modalias helps coldplug: modprobe $(cat .../modalias) */
419 &dev_attr_modalias.attr,
423 static struct attribute_group i2c_dev_attr_group = {
424 .attrs = i2c_dev_attrs,
427 static const struct attribute_group *i2c_dev_attr_groups[] = {
432 static const struct dev_pm_ops i2c_device_pm_ops = {
433 .suspend = i2c_device_pm_suspend,
434 .resume = i2c_device_pm_resume,
435 .freeze = i2c_device_pm_freeze,
436 .thaw = i2c_device_pm_thaw,
437 .poweroff = i2c_device_pm_poweroff,
438 .restore = i2c_device_pm_restore,
440 pm_generic_runtime_suspend,
441 pm_generic_runtime_resume,
446 struct bus_type i2c_bus_type = {
448 .match = i2c_device_match,
449 .probe = i2c_device_probe,
450 .remove = i2c_device_remove,
451 .shutdown = i2c_device_shutdown,
452 .pm = &i2c_device_pm_ops,
454 EXPORT_SYMBOL_GPL(i2c_bus_type);
456 static struct device_type i2c_client_type = {
457 .groups = i2c_dev_attr_groups,
458 .uevent = i2c_device_uevent,
459 .release = i2c_client_dev_release,
464 * i2c_verify_client - return parameter as i2c_client, or NULL
465 * @dev: device, probably from some driver model iterator
467 * When traversing the driver model tree, perhaps using driver model
468 * iterators like @device_for_each_child(), you can't assume very much
469 * about the nodes you find. Use this function to avoid oopses caused
470 * by wrongly treating some non-I2C device as an i2c_client.
472 struct i2c_client *i2c_verify_client(struct device *dev)
474 return (dev->type == &i2c_client_type)
478 EXPORT_SYMBOL(i2c_verify_client);
481 /* This is a permissive address validity check, I2C address map constraints
482 * are purposely not enforced, except for the general call address. */
483 static int i2c_check_client_addr_validity(const struct i2c_client *client)
485 if (client->flags & I2C_CLIENT_TEN) {
486 /* 10-bit address, all values are valid */
487 if (client->addr > 0x3ff)
490 /* 7-bit address, reject the general call address */
491 if (client->addr == 0x00 || client->addr > 0x7f)
497 /* And this is a strict address validity check, used when probing. If a
498 * device uses a reserved address, then it shouldn't be probed. 7-bit
499 * addressing is assumed, 10-bit address devices are rare and should be
500 * explicitly enumerated. */
501 static int i2c_check_addr_validity(unsigned short addr)
504 * Reserved addresses per I2C specification:
505 * 0x00 General call address / START byte
507 * 0x02 Reserved for different bus format
508 * 0x03 Reserved for future purposes
509 * 0x04-0x07 Hs-mode master code
510 * 0x78-0x7b 10-bit slave addressing
511 * 0x7c-0x7f Reserved for future purposes
513 if (addr < 0x08 || addr > 0x77)
518 static int __i2c_check_addr_busy(struct device *dev, void *addrp)
520 struct i2c_client *client = i2c_verify_client(dev);
521 int addr = *(int *)addrp;
523 if (client && client->addr == addr)
528 /* walk up mux tree */
529 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
531 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
534 result = device_for_each_child(&adapter->dev, &addr,
535 __i2c_check_addr_busy);
537 if (!result && parent)
538 result = i2c_check_mux_parents(parent, addr);
543 /* recurse down mux tree */
544 static int i2c_check_mux_children(struct device *dev, void *addrp)
548 if (dev->type == &i2c_adapter_type)
549 result = device_for_each_child(dev, addrp,
550 i2c_check_mux_children);
552 result = __i2c_check_addr_busy(dev, addrp);
557 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
559 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
563 result = i2c_check_mux_parents(parent, addr);
566 result = device_for_each_child(&adapter->dev, &addr,
567 i2c_check_mux_children);
573 * i2c_lock_adapter - Get exclusive access to an I2C bus segment
574 * @adapter: Target I2C bus segment
576 void i2c_lock_adapter(struct i2c_adapter *adapter)
578 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
581 i2c_lock_adapter(parent);
583 rt_mutex_lock(&adapter->bus_lock);
585 EXPORT_SYMBOL_GPL(i2c_lock_adapter);
588 * i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment
589 * @adapter: Target I2C bus segment
591 static int i2c_trylock_adapter(struct i2c_adapter *adapter)
593 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
596 return i2c_trylock_adapter(parent);
598 return rt_mutex_trylock(&adapter->bus_lock);
602 * i2c_unlock_adapter - Release exclusive access to an I2C bus segment
603 * @adapter: Target I2C bus segment
605 void i2c_unlock_adapter(struct i2c_adapter *adapter)
607 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
610 i2c_unlock_adapter(parent);
612 rt_mutex_unlock(&adapter->bus_lock);
614 EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
617 * i2c_new_device - instantiate an i2c device
618 * @adap: the adapter managing the device
619 * @info: describes one I2C device; bus_num is ignored
622 * Create an i2c device. Binding is handled through driver model
623 * probe()/remove() methods. A driver may be bound to this device when we
624 * return from this function, or any later moment (e.g. maybe hotplugging will
625 * load the driver module). This call is not appropriate for use by mainboard
626 * initialization logic, which usually runs during an arch_initcall() long
627 * before any i2c_adapter could exist.
629 * This returns the new i2c client, which may be saved for later use with
630 * i2c_unregister_device(); or NULL to indicate an error.
633 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
635 struct i2c_client *client;
638 client = kzalloc(sizeof *client, GFP_KERNEL);
642 client->adapter = adap;
644 client->dev.platform_data = info->platform_data;
647 client->dev.archdata = *info->archdata;
649 client->flags = info->flags;
650 client->addr = info->addr;
651 client->irq = info->irq;
653 strlcpy(client->name, info->type, sizeof(client->name));
655 /* Check for address validity */
656 status = i2c_check_client_addr_validity(client);
658 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
659 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
663 /* Check for address business */
664 status = i2c_check_addr_busy(adap, client->addr);
668 client->dev.parent = &client->adapter->dev;
669 client->dev.bus = &i2c_bus_type;
670 client->dev.type = &i2c_client_type;
671 client->dev.of_node = info->of_node;
672 ACPI_HANDLE_SET(&client->dev, info->acpi_node.handle);
674 /* For 10-bit clients, add an arbitrary offset to avoid collisions */
675 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
676 client->addr | ((client->flags & I2C_CLIENT_TEN)
678 status = device_register(&client->dev);
682 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
683 client->name, dev_name(&client->dev));
688 dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
689 "(%d)\n", client->name, client->addr, status);
694 EXPORT_SYMBOL_GPL(i2c_new_device);
698 * i2c_unregister_device - reverse effect of i2c_new_device()
699 * @client: value returned from i2c_new_device()
702 void i2c_unregister_device(struct i2c_client *client)
704 device_unregister(&client->dev);
706 EXPORT_SYMBOL_GPL(i2c_unregister_device);
709 static const struct i2c_device_id dummy_id[] = {
714 static int dummy_probe(struct i2c_client *client,
715 const struct i2c_device_id *id)
720 static int dummy_remove(struct i2c_client *client)
725 static struct i2c_driver dummy_driver = {
726 .driver.name = "dummy",
727 .probe = dummy_probe,
728 .remove = dummy_remove,
729 .id_table = dummy_id,
733 * i2c_new_dummy - return a new i2c device bound to a dummy driver
734 * @adapter: the adapter managing the device
735 * @address: seven bit address to be used
738 * This returns an I2C client bound to the "dummy" driver, intended for use
739 * with devices that consume multiple addresses. Examples of such chips
740 * include various EEPROMS (like 24c04 and 24c08 models).
742 * These dummy devices have two main uses. First, most I2C and SMBus calls
743 * except i2c_transfer() need a client handle; the dummy will be that handle.
744 * And second, this prevents the specified address from being bound to a
747 * This returns the new i2c client, which should be saved for later use with
748 * i2c_unregister_device(); or NULL to indicate an error.
750 struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
752 struct i2c_board_info info = {
753 I2C_BOARD_INFO("dummy", address),
756 return i2c_new_device(adapter, &info);
758 EXPORT_SYMBOL_GPL(i2c_new_dummy);
760 /* ------------------------------------------------------------------------- */
762 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
764 static void i2c_adapter_dev_release(struct device *dev)
766 struct i2c_adapter *adap = to_i2c_adapter(dev);
767 complete(&adap->dev_released);
771 * This function is only needed for mutex_lock_nested, so it is never
772 * called unless locking correctness checking is enabled. Thus we
773 * make it inline to avoid a compiler warning. That's what gcc ends up
776 static inline unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
778 unsigned int depth = 0;
780 while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
787 * Let users instantiate I2C devices through sysfs. This can be used when
788 * platform initialization code doesn't contain the proper data for
789 * whatever reason. Also useful for drivers that do device detection and
790 * detection fails, either because the device uses an unexpected address,
791 * or this is a compatible device with different ID register values.
793 * Parameter checking may look overzealous, but we really don't want
794 * the user to provide incorrect parameters.
797 i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
798 const char *buf, size_t count)
800 struct i2c_adapter *adap = to_i2c_adapter(dev);
801 struct i2c_board_info info;
802 struct i2c_client *client;
806 memset(&info, 0, sizeof(struct i2c_board_info));
808 blank = strchr(buf, ' ');
810 dev_err(dev, "%s: Missing parameters\n", "new_device");
813 if (blank - buf > I2C_NAME_SIZE - 1) {
814 dev_err(dev, "%s: Invalid device name\n", "new_device");
817 memcpy(info.type, buf, blank - buf);
819 /* Parse remaining parameters, reject extra parameters */
820 res = sscanf(++blank, "%hi%c", &info.addr, &end);
822 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
825 if (res > 1 && end != '\n') {
826 dev_err(dev, "%s: Extra parameters\n", "new_device");
830 client = i2c_new_device(adap, &info);
834 /* Keep track of the added device */
835 mutex_lock(&adap->userspace_clients_lock);
836 list_add_tail(&client->detected, &adap->userspace_clients);
837 mutex_unlock(&adap->userspace_clients_lock);
838 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
839 info.type, info.addr);
845 * And of course let the users delete the devices they instantiated, if
846 * they got it wrong. This interface can only be used to delete devices
847 * instantiated by i2c_sysfs_new_device above. This guarantees that we
848 * don't delete devices to which some kernel code still has references.
850 * Parameter checking may look overzealous, but we really don't want
851 * the user to delete the wrong device.
854 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
855 const char *buf, size_t count)
857 struct i2c_adapter *adap = to_i2c_adapter(dev);
858 struct i2c_client *client, *next;
863 /* Parse parameters, reject extra parameters */
864 res = sscanf(buf, "%hi%c", &addr, &end);
866 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
869 if (res > 1 && end != '\n') {
870 dev_err(dev, "%s: Extra parameters\n", "delete_device");
874 /* Make sure the device was added through sysfs */
876 mutex_lock_nested(&adap->userspace_clients_lock,
877 i2c_adapter_depth(adap));
878 list_for_each_entry_safe(client, next, &adap->userspace_clients,
880 if (client->addr == addr) {
881 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
882 "delete_device", client->name, client->addr);
884 list_del(&client->detected);
885 i2c_unregister_device(client);
890 mutex_unlock(&adap->userspace_clients_lock);
893 dev_err(dev, "%s: Can't find device in list\n",
898 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
899 static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
900 i2c_sysfs_delete_device);
902 static struct attribute *i2c_adapter_attrs[] = {
904 &dev_attr_new_device.attr,
905 &dev_attr_delete_device.attr,
909 static struct attribute_group i2c_adapter_attr_group = {
910 .attrs = i2c_adapter_attrs,
913 static const struct attribute_group *i2c_adapter_attr_groups[] = {
914 &i2c_adapter_attr_group,
918 struct device_type i2c_adapter_type = {
919 .groups = i2c_adapter_attr_groups,
920 .release = i2c_adapter_dev_release,
922 EXPORT_SYMBOL_GPL(i2c_adapter_type);
925 * i2c_verify_adapter - return parameter as i2c_adapter or NULL
926 * @dev: device, probably from some driver model iterator
928 * When traversing the driver model tree, perhaps using driver model
929 * iterators like @device_for_each_child(), you can't assume very much
930 * about the nodes you find. Use this function to avoid oopses caused
931 * by wrongly treating some non-I2C device as an i2c_adapter.
933 struct i2c_adapter *i2c_verify_adapter(struct device *dev)
935 return (dev->type == &i2c_adapter_type)
936 ? to_i2c_adapter(dev)
939 EXPORT_SYMBOL(i2c_verify_adapter);
941 #ifdef CONFIG_I2C_COMPAT
942 static struct class_compat *i2c_adapter_compat_class;
945 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
947 struct i2c_devinfo *devinfo;
949 down_read(&__i2c_board_lock);
950 list_for_each_entry(devinfo, &__i2c_board_list, list) {
951 if (devinfo->busnum == adapter->nr
952 && !i2c_new_device(adapter,
953 &devinfo->board_info))
954 dev_err(&adapter->dev,
955 "Can't create device at 0x%02x\n",
956 devinfo->board_info.addr);
958 up_read(&__i2c_board_lock);
961 /* OF support code */
963 #if IS_ENABLED(CONFIG_OF)
964 static void of_i2c_register_devices(struct i2c_adapter *adap)
967 struct device_node *node;
969 /* Only register child devices if the adapter has a node pointer set */
970 if (!adap->dev.of_node)
973 dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
975 for_each_available_child_of_node(adap->dev.of_node, node) {
976 struct i2c_board_info info = {};
977 struct dev_archdata dev_ad = {};
981 dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
983 if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
984 dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
989 addr = of_get_property(node, "reg", &len);
990 if (!addr || (len < sizeof(int))) {
991 dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
996 info.addr = be32_to_cpup(addr);
997 if (info.addr > (1 << 10) - 1) {
998 dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
999 info.addr, node->full_name);
1003 info.irq = irq_of_parse_and_map(node, 0);
1004 info.of_node = of_node_get(node);
1005 info.archdata = &dev_ad;
1007 if (of_get_property(node, "wakeup-source", NULL))
1008 info.flags |= I2C_CLIENT_WAKE;
1010 request_module("%s%s", I2C_MODULE_PREFIX, info.type);
1012 result = i2c_new_device(adap, &info);
1013 if (result == NULL) {
1014 dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
1017 irq_dispose_mapping(info.irq);
1023 static int of_dev_node_match(struct device *dev, void *data)
1025 return dev->of_node == data;
1028 /* must call put_device() when done with returned i2c_client device */
1029 struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
1033 dev = bus_find_device(&i2c_bus_type, NULL, node,
1038 return i2c_verify_client(dev);
1040 EXPORT_SYMBOL(of_find_i2c_device_by_node);
1042 /* must call put_device() when done with returned i2c_adapter device */
1043 struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
1047 dev = bus_find_device(&i2c_bus_type, NULL, node,
1052 return i2c_verify_adapter(dev);
1054 EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
1056 static void of_i2c_register_devices(struct i2c_adapter *adap) { }
1057 #endif /* CONFIG_OF */
1059 /* ACPI support code */
1061 #if IS_ENABLED(CONFIG_ACPI)
1062 static int acpi_i2c_add_resource(struct acpi_resource *ares, void *data)
1064 struct i2c_board_info *info = data;
1066 if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
1067 struct acpi_resource_i2c_serialbus *sb;
1069 sb = &ares->data.i2c_serial_bus;
1070 if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_I2C) {
1071 info->addr = sb->slave_address;
1072 if (sb->access_mode == ACPI_I2C_10BIT_MODE)
1073 info->flags |= I2C_CLIENT_TEN;
1075 } else if (info->irq < 0) {
1078 if (acpi_dev_resource_interrupt(ares, 0, &r))
1079 info->irq = r.start;
1082 /* Tell the ACPI core to skip this resource */
1086 static acpi_status acpi_i2c_add_device(acpi_handle handle, u32 level,
1087 void *data, void **return_value)
1089 struct i2c_adapter *adapter = data;
1090 struct list_head resource_list;
1091 struct i2c_board_info info;
1092 struct acpi_device *adev;
1095 if (acpi_bus_get_device(handle, &adev))
1097 if (acpi_bus_get_status(adev) || !adev->status.present)
1100 memset(&info, 0, sizeof(info));
1101 info.acpi_node.handle = handle;
1104 INIT_LIST_HEAD(&resource_list);
1105 ret = acpi_dev_get_resources(adev, &resource_list,
1106 acpi_i2c_add_resource, &info);
1107 acpi_dev_free_resource_list(&resource_list);
1109 if (ret < 0 || !info.addr)
1112 strlcpy(info.type, dev_name(&adev->dev), sizeof(info.type));
1113 if (!i2c_new_device(adapter, &info)) {
1114 dev_err(&adapter->dev,
1115 "failed to add I2C device %s from ACPI\n",
1116 dev_name(&adev->dev));
1123 * acpi_i2c_register_devices - enumerate I2C slave devices behind adapter
1124 * @adap: pointer to adapter
1126 * Enumerate all I2C slave devices behind this adapter by walking the ACPI
1127 * namespace. When a device is found it will be added to the Linux device
1128 * model and bound to the corresponding ACPI handle.
1130 static void acpi_i2c_register_devices(struct i2c_adapter *adap)
1135 if (!adap->dev.parent)
1138 handle = ACPI_HANDLE(adap->dev.parent);
1142 status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
1143 acpi_i2c_add_device, NULL,
1145 if (ACPI_FAILURE(status))
1146 dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
1149 static inline void acpi_i2c_register_devices(struct i2c_adapter *adap) {}
1150 #endif /* CONFIG_ACPI */
1152 static int i2c_do_add_adapter(struct i2c_driver *driver,
1153 struct i2c_adapter *adap)
1155 /* Detect supported devices on that bus, and instantiate them */
1156 i2c_detect(adap, driver);
1158 /* Let legacy drivers scan this bus for matching devices */
1159 if (driver->attach_adapter) {
1160 dev_warn(&adap->dev, "%s: attach_adapter method is deprecated\n",
1161 driver->driver.name);
1162 dev_warn(&adap->dev, "Please use another way to instantiate "
1163 "your i2c_client\n");
1164 /* We ignore the return code; if it fails, too bad */
1165 driver->attach_adapter(adap);
1170 static int __process_new_adapter(struct device_driver *d, void *data)
1172 return i2c_do_add_adapter(to_i2c_driver(d), data);
1175 static int i2c_register_adapter(struct i2c_adapter *adap)
1179 /* Can't register until after driver model init */
1180 if (unlikely(WARN_ON(!i2c_bus_type.p))) {
1186 if (unlikely(adap->name[0] == '\0')) {
1187 pr_err("i2c-core: Attempt to register an adapter with "
1191 if (unlikely(!adap->algo)) {
1192 pr_err("i2c-core: Attempt to register adapter '%s' with "
1193 "no algo!\n", adap->name);
1197 rt_mutex_init(&adap->bus_lock);
1198 mutex_init(&adap->userspace_clients_lock);
1199 INIT_LIST_HEAD(&adap->userspace_clients);
1201 /* Set default timeout to 1 second if not already set */
1202 if (adap->timeout == 0)
1205 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
1206 adap->dev.bus = &i2c_bus_type;
1207 adap->dev.type = &i2c_adapter_type;
1208 res = device_register(&adap->dev);
1212 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1214 #ifdef CONFIG_I2C_COMPAT
1215 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
1218 dev_warn(&adap->dev,
1219 "Failed to create compatibility class link\n");
1222 /* bus recovery specific initialization */
1223 if (adap->bus_recovery_info) {
1224 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
1226 if (!bri->recover_bus) {
1227 dev_err(&adap->dev, "No recover_bus() found, not using recovery\n");
1228 adap->bus_recovery_info = NULL;
1232 /* Generic GPIO recovery */
1233 if (bri->recover_bus == i2c_generic_gpio_recovery) {
1234 if (!gpio_is_valid(bri->scl_gpio)) {
1235 dev_err(&adap->dev, "Invalid SCL gpio, not using recovery\n");
1236 adap->bus_recovery_info = NULL;
1240 if (gpio_is_valid(bri->sda_gpio))
1241 bri->get_sda = get_sda_gpio_value;
1243 bri->get_sda = NULL;
1245 bri->get_scl = get_scl_gpio_value;
1246 bri->set_scl = set_scl_gpio_value;
1247 } else if (!bri->set_scl || !bri->get_scl) {
1248 /* Generic SCL recovery */
1249 dev_err(&adap->dev, "No {get|set}_gpio() found, not using recovery\n");
1250 adap->bus_recovery_info = NULL;
1255 /* create pre-declared device nodes */
1256 of_i2c_register_devices(adap);
1257 acpi_i2c_register_devices(adap);
1259 if (adap->nr < __i2c_first_dynamic_bus_num)
1260 i2c_scan_static_board_info(adap);
1262 /* Notify drivers */
1263 mutex_lock(&core_lock);
1264 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
1265 mutex_unlock(&core_lock);
1270 mutex_lock(&core_lock);
1271 idr_remove(&i2c_adapter_idr, adap->nr);
1272 mutex_unlock(&core_lock);
1277 * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1278 * @adap: the adapter to register (with adap->nr initialized)
1279 * Context: can sleep
1281 * See i2c_add_numbered_adapter() for details.
1283 static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1287 mutex_lock(&core_lock);
1288 id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,
1290 mutex_unlock(&core_lock);
1292 return id == -ENOSPC ? -EBUSY : id;
1294 return i2c_register_adapter(adap);
1298 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
1299 * @adapter: the adapter to add
1300 * Context: can sleep
1302 * This routine is used to declare an I2C adapter when its bus number
1303 * doesn't matter or when its bus number is specified by an dt alias.
1304 * Examples of bases when the bus number doesn't matter: I2C adapters
1305 * dynamically added by USB links or PCI plugin cards.
1307 * When this returns zero, a new bus number was allocated and stored
1308 * in adap->nr, and the specified adapter became available for clients.
1309 * Otherwise, a negative errno value is returned.
1311 int i2c_add_adapter(struct i2c_adapter *adapter)
1313 struct device *dev = &adapter->dev;
1317 id = of_alias_get_id(dev->of_node, "i2c");
1320 return __i2c_add_numbered_adapter(adapter);
1324 mutex_lock(&core_lock);
1325 id = idr_alloc(&i2c_adapter_idr, adapter,
1326 __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
1327 mutex_unlock(&core_lock);
1333 return i2c_register_adapter(adapter);
1335 EXPORT_SYMBOL(i2c_add_adapter);
1338 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1339 * @adap: the adapter to register (with adap->nr initialized)
1340 * Context: can sleep
1342 * This routine is used to declare an I2C adapter when its bus number
1343 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
1344 * or otherwise built in to the system's mainboard, and where i2c_board_info
1345 * is used to properly configure I2C devices.
1347 * If the requested bus number is set to -1, then this function will behave
1348 * identically to i2c_add_adapter, and will dynamically assign a bus number.
1350 * If no devices have pre-been declared for this bus, then be sure to
1351 * register the adapter before any dynamically allocated ones. Otherwise
1352 * the required bus ID may not be available.
1354 * When this returns zero, the specified adapter became available for
1355 * clients using the bus number provided in adap->nr. Also, the table
1356 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
1357 * and the appropriate driver model device nodes are created. Otherwise, a
1358 * negative errno value is returned.
1360 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1362 if (adap->nr == -1) /* -1 means dynamically assign bus id */
1363 return i2c_add_adapter(adap);
1365 return __i2c_add_numbered_adapter(adap);
1367 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1369 static void i2c_do_del_adapter(struct i2c_driver *driver,
1370 struct i2c_adapter *adapter)
1372 struct i2c_client *client, *_n;
1374 /* Remove the devices we created ourselves as the result of hardware
1375 * probing (using a driver's detect method) */
1376 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1377 if (client->adapter == adapter) {
1378 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1379 client->name, client->addr);
1380 list_del(&client->detected);
1381 i2c_unregister_device(client);
1386 static int __unregister_client(struct device *dev, void *dummy)
1388 struct i2c_client *client = i2c_verify_client(dev);
1389 if (client && strcmp(client->name, "dummy"))
1390 i2c_unregister_device(client);
1394 static int __unregister_dummy(struct device *dev, void *dummy)
1396 struct i2c_client *client = i2c_verify_client(dev);
1398 i2c_unregister_device(client);
1402 static int __process_removed_adapter(struct device_driver *d, void *data)
1404 i2c_do_del_adapter(to_i2c_driver(d), data);
1409 * i2c_del_adapter - unregister I2C adapter
1410 * @adap: the adapter being unregistered
1411 * Context: can sleep
1413 * This unregisters an I2C adapter which was previously registered
1414 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1416 void i2c_del_adapter(struct i2c_adapter *adap)
1418 struct i2c_adapter *found;
1419 struct i2c_client *client, *next;
1421 /* First make sure that this adapter was ever added */
1422 mutex_lock(&core_lock);
1423 found = idr_find(&i2c_adapter_idr, adap->nr);
1424 mutex_unlock(&core_lock);
1425 if (found != adap) {
1426 pr_debug("i2c-core: attempting to delete unregistered "
1427 "adapter [%s]\n", adap->name);
1431 /* Tell drivers about this removal */
1432 mutex_lock(&core_lock);
1433 bus_for_each_drv(&i2c_bus_type, NULL, adap,
1434 __process_removed_adapter);
1435 mutex_unlock(&core_lock);
1437 /* Remove devices instantiated from sysfs */
1438 mutex_lock_nested(&adap->userspace_clients_lock,
1439 i2c_adapter_depth(adap));
1440 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1442 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1444 list_del(&client->detected);
1445 i2c_unregister_device(client);
1447 mutex_unlock(&adap->userspace_clients_lock);
1449 /* Detach any active clients. This can't fail, thus we do not
1450 * check the returned value. This is a two-pass process, because
1451 * we can't remove the dummy devices during the first pass: they
1452 * could have been instantiated by real devices wishing to clean
1453 * them up properly, so we give them a chance to do that first. */
1454 device_for_each_child(&adap->dev, NULL, __unregister_client);
1455 device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1457 #ifdef CONFIG_I2C_COMPAT
1458 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1462 /* device name is gone after device_unregister */
1463 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1465 /* clean up the sysfs representation */
1466 init_completion(&adap->dev_released);
1467 device_unregister(&adap->dev);
1469 /* wait for sysfs to drop all references */
1470 wait_for_completion(&adap->dev_released);
1473 mutex_lock(&core_lock);
1474 idr_remove(&i2c_adapter_idr, adap->nr);
1475 mutex_unlock(&core_lock);
1477 /* Clear the device structure in case this adapter is ever going to be
1479 memset(&adap->dev, 0, sizeof(adap->dev));
1481 EXPORT_SYMBOL(i2c_del_adapter);
1483 /* ------------------------------------------------------------------------- */
1485 int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *))
1489 mutex_lock(&core_lock);
1490 res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
1491 mutex_unlock(&core_lock);
1495 EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1497 static int __process_new_driver(struct device *dev, void *data)
1499 if (dev->type != &i2c_adapter_type)
1501 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1505 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1506 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1509 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1513 /* Can't register until after driver model init */
1514 if (unlikely(WARN_ON(!i2c_bus_type.p)))
1517 /* add the driver to the list of i2c drivers in the driver core */
1518 driver->driver.owner = owner;
1519 driver->driver.bus = &i2c_bus_type;
1521 /* When registration returns, the driver core
1522 * will have called probe() for all matching-but-unbound devices.
1524 res = driver_register(&driver->driver);
1528 /* Drivers should switch to dev_pm_ops instead. */
1529 if (driver->suspend)
1530 pr_warn("i2c-core: driver [%s] using legacy suspend method\n",
1531 driver->driver.name);
1533 pr_warn("i2c-core: driver [%s] using legacy resume method\n",
1534 driver->driver.name);
1536 pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
1538 INIT_LIST_HEAD(&driver->clients);
1539 /* Walk the adapters that are already present */
1540 i2c_for_each_dev(driver, __process_new_driver);
1544 EXPORT_SYMBOL(i2c_register_driver);
1546 static int __process_removed_driver(struct device *dev, void *data)
1548 if (dev->type == &i2c_adapter_type)
1549 i2c_do_del_adapter(data, to_i2c_adapter(dev));
1554 * i2c_del_driver - unregister I2C driver
1555 * @driver: the driver being unregistered
1556 * Context: can sleep
1558 void i2c_del_driver(struct i2c_driver *driver)
1560 i2c_for_each_dev(driver, __process_removed_driver);
1562 driver_unregister(&driver->driver);
1563 pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
1565 EXPORT_SYMBOL(i2c_del_driver);
1567 /* ------------------------------------------------------------------------- */
1570 * i2c_use_client - increments the reference count of the i2c client structure
1571 * @client: the client being referenced
1573 * Each live reference to a client should be refcounted. The driver model does
1574 * that automatically as part of driver binding, so that most drivers don't
1575 * need to do this explicitly: they hold a reference until they're unbound
1578 * A pointer to the client with the incremented reference counter is returned.
1580 struct i2c_client *i2c_use_client(struct i2c_client *client)
1582 if (client && get_device(&client->dev))
1586 EXPORT_SYMBOL(i2c_use_client);
1589 * i2c_release_client - release a use of the i2c client structure
1590 * @client: the client being no longer referenced
1592 * Must be called when a user of a client is finished with it.
1594 void i2c_release_client(struct i2c_client *client)
1597 put_device(&client->dev);
1599 EXPORT_SYMBOL(i2c_release_client);
1601 struct i2c_cmd_arg {
1606 static int i2c_cmd(struct device *dev, void *_arg)
1608 struct i2c_client *client = i2c_verify_client(dev);
1609 struct i2c_cmd_arg *arg = _arg;
1610 struct i2c_driver *driver;
1612 if (!client || !client->dev.driver)
1615 driver = to_i2c_driver(client->dev.driver);
1616 if (driver->command)
1617 driver->command(client, arg->cmd, arg->arg);
1621 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1623 struct i2c_cmd_arg cmd_arg;
1627 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1629 EXPORT_SYMBOL(i2c_clients_command);
1631 static int __init i2c_init(void)
1635 retval = bus_register(&i2c_bus_type);
1638 #ifdef CONFIG_I2C_COMPAT
1639 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1640 if (!i2c_adapter_compat_class) {
1645 retval = i2c_add_driver(&dummy_driver);
1651 #ifdef CONFIG_I2C_COMPAT
1652 class_compat_unregister(i2c_adapter_compat_class);
1655 bus_unregister(&i2c_bus_type);
1659 static void __exit i2c_exit(void)
1661 i2c_del_driver(&dummy_driver);
1662 #ifdef CONFIG_I2C_COMPAT
1663 class_compat_unregister(i2c_adapter_compat_class);
1665 bus_unregister(&i2c_bus_type);
1668 /* We must initialize early, because some subsystems register i2c drivers
1669 * in subsys_initcall() code, but are linked (and initialized) before i2c.
1671 postcore_initcall(i2c_init);
1672 module_exit(i2c_exit);
1674 /* ----------------------------------------------------
1675 * the functional interface to the i2c busses.
1676 * ----------------------------------------------------
1680 * __i2c_transfer - unlocked flavor of i2c_transfer
1681 * @adap: Handle to I2C bus
1682 * @msgs: One or more messages to execute before STOP is issued to
1683 * terminate the operation; each message begins with a START.
1684 * @num: Number of messages to be executed.
1686 * Returns negative errno, else the number of messages executed.
1688 * Adapter lock must be held when calling this function. No debug logging
1689 * takes place. adap->algo->master_xfer existence isn't checked.
1691 int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1693 unsigned long orig_jiffies;
1696 /* Retry automatically on arbitration loss */
1697 orig_jiffies = jiffies;
1698 for (ret = 0, try = 0; try <= adap->retries; try++) {
1699 ret = adap->algo->master_xfer(adap, msgs, num);
1702 if (time_after(jiffies, orig_jiffies + adap->timeout))
1708 EXPORT_SYMBOL(__i2c_transfer);
1711 * i2c_transfer - execute a single or combined I2C message
1712 * @adap: Handle to I2C bus
1713 * @msgs: One or more messages to execute before STOP is issued to
1714 * terminate the operation; each message begins with a START.
1715 * @num: Number of messages to be executed.
1717 * Returns negative errno, else the number of messages executed.
1719 * Note that there is no requirement that each message be sent to
1720 * the same slave address, although that is the most common model.
1722 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1726 /* REVISIT the fault reporting model here is weak:
1728 * - When we get an error after receiving N bytes from a slave,
1729 * there is no way to report "N".
1731 * - When we get a NAK after transmitting N bytes to a slave,
1732 * there is no way to report "N" ... or to let the master
1733 * continue executing the rest of this combined message, if
1734 * that's the appropriate response.
1736 * - When for example "num" is two and we successfully complete
1737 * the first message but get an error part way through the
1738 * second, it's unclear whether that should be reported as
1739 * one (discarding status on the second message) or errno
1740 * (discarding status on the first one).
1743 if (adap->algo->master_xfer) {
1745 for (ret = 0; ret < num; ret++) {
1746 dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
1747 "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
1748 ? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
1749 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1753 if (in_atomic() || irqs_disabled()) {
1754 ret = i2c_trylock_adapter(adap);
1756 /* I2C activity is ongoing. */
1759 i2c_lock_adapter(adap);
1762 ret = __i2c_transfer(adap, msgs, num);
1763 i2c_unlock_adapter(adap);
1767 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1771 EXPORT_SYMBOL(i2c_transfer);
1774 * i2c_master_send - issue a single I2C message in master transmit mode
1775 * @client: Handle to slave device
1776 * @buf: Data that will be written to the slave
1777 * @count: How many bytes to write, must be less than 64k since msg.len is u16
1779 * Returns negative errno, or else the number of bytes written.
1781 int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
1784 struct i2c_adapter *adap = client->adapter;
1787 msg.addr = client->addr;
1788 msg.flags = client->flags & I2C_M_TEN;
1790 msg.buf = (char *)buf;
1792 ret = i2c_transfer(adap, &msg, 1);
1795 * If everything went ok (i.e. 1 msg transmitted), return #bytes
1796 * transmitted, else error code.
1798 return (ret == 1) ? count : ret;
1800 EXPORT_SYMBOL(i2c_master_send);
1803 * i2c_master_recv - issue a single I2C message in master receive mode
1804 * @client: Handle to slave device
1805 * @buf: Where to store data read from slave
1806 * @count: How many bytes to read, must be less than 64k since msg.len is u16
1808 * Returns negative errno, or else the number of bytes read.
1810 int i2c_master_recv(const struct i2c_client *client, char *buf, int count)
1812 struct i2c_adapter *adap = client->adapter;
1816 msg.addr = client->addr;
1817 msg.flags = client->flags & I2C_M_TEN;
1818 msg.flags |= I2C_M_RD;
1822 ret = i2c_transfer(adap, &msg, 1);
1825 * If everything went ok (i.e. 1 msg received), return #bytes received,
1828 return (ret == 1) ? count : ret;
1830 EXPORT_SYMBOL(i2c_master_recv);
1832 /* ----------------------------------------------------
1833 * the i2c address scanning function
1834 * Will not work for 10-bit addresses!
1835 * ----------------------------------------------------
1839 * Legacy default probe function, mostly relevant for SMBus. The default
1840 * probe method is a quick write, but it is known to corrupt the 24RF08
1841 * EEPROMs due to a state machine bug, and could also irreversibly
1842 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
1843 * we use a short byte read instead. Also, some bus drivers don't implement
1844 * quick write, so we fallback to a byte read in that case too.
1845 * On x86, there is another special case for FSC hardware monitoring chips,
1846 * which want regular byte reads (address 0x73.) Fortunately, these are the
1847 * only known chips using this I2C address on PC hardware.
1848 * Returns 1 if probe succeeded, 0 if not.
1850 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
1853 union i2c_smbus_data dummy;
1856 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
1857 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
1858 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1859 I2C_SMBUS_BYTE_DATA, &dummy);
1862 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
1863 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
1864 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
1865 I2C_SMBUS_QUICK, NULL);
1866 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
1867 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1868 I2C_SMBUS_BYTE, &dummy);
1870 dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
1878 static int i2c_detect_address(struct i2c_client *temp_client,
1879 struct i2c_driver *driver)
1881 struct i2c_board_info info;
1882 struct i2c_adapter *adapter = temp_client->adapter;
1883 int addr = temp_client->addr;
1886 /* Make sure the address is valid */
1887 err = i2c_check_addr_validity(addr);
1889 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
1894 /* Skip if already in use */
1895 if (i2c_check_addr_busy(adapter, addr))
1898 /* Make sure there is something at this address */
1899 if (!i2c_default_probe(adapter, addr))
1902 /* Finally call the custom detection function */
1903 memset(&info, 0, sizeof(struct i2c_board_info));
1905 err = driver->detect(temp_client, &info);
1907 /* -ENODEV is returned if the detection fails. We catch it
1908 here as this isn't an error. */
1909 return err == -ENODEV ? 0 : err;
1912 /* Consistency check */
1913 if (info.type[0] == '\0') {
1914 dev_err(&adapter->dev, "%s detection function provided "
1915 "no name for 0x%x\n", driver->driver.name,
1918 struct i2c_client *client;
1920 /* Detection succeeded, instantiate the device */
1921 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
1922 info.type, info.addr);
1923 client = i2c_new_device(adapter, &info);
1925 list_add_tail(&client->detected, &driver->clients);
1927 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
1928 info.type, info.addr);
1933 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
1935 const unsigned short *address_list;
1936 struct i2c_client *temp_client;
1938 int adap_id = i2c_adapter_id(adapter);
1940 address_list = driver->address_list;
1941 if (!driver->detect || !address_list)
1944 /* Stop here if the classes do not match */
1945 if (!(adapter->class & driver->class))
1948 /* Set up a temporary client to help detect callback */
1949 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
1952 temp_client->adapter = adapter;
1954 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
1955 dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
1956 "addr 0x%02x\n", adap_id, address_list[i]);
1957 temp_client->addr = address_list[i];
1958 err = i2c_detect_address(temp_client, driver);
1967 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
1969 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1970 I2C_SMBUS_QUICK, NULL) >= 0;
1972 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
1975 i2c_new_probed_device(struct i2c_adapter *adap,
1976 struct i2c_board_info *info,
1977 unsigned short const *addr_list,
1978 int (*probe)(struct i2c_adapter *, unsigned short addr))
1983 probe = i2c_default_probe;
1985 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
1986 /* Check address validity */
1987 if (i2c_check_addr_validity(addr_list[i]) < 0) {
1988 dev_warn(&adap->dev, "Invalid 7-bit address "
1989 "0x%02x\n", addr_list[i]);
1993 /* Check address availability */
1994 if (i2c_check_addr_busy(adap, addr_list[i])) {
1995 dev_dbg(&adap->dev, "Address 0x%02x already in "
1996 "use, not probing\n", addr_list[i]);
2000 /* Test address responsiveness */
2001 if (probe(adap, addr_list[i]))
2005 if (addr_list[i] == I2C_CLIENT_END) {
2006 dev_dbg(&adap->dev, "Probing failed, no device found\n");
2010 info->addr = addr_list[i];
2011 return i2c_new_device(adap, info);
2013 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
2015 struct i2c_adapter *i2c_get_adapter(int nr)
2017 struct i2c_adapter *adapter;
2019 mutex_lock(&core_lock);
2020 adapter = idr_find(&i2c_adapter_idr, nr);
2021 if (adapter && !try_module_get(adapter->owner))
2024 mutex_unlock(&core_lock);
2027 EXPORT_SYMBOL(i2c_get_adapter);
2029 void i2c_put_adapter(struct i2c_adapter *adap)
2032 module_put(adap->owner);
2034 EXPORT_SYMBOL(i2c_put_adapter);
2036 /* The SMBus parts */
2038 #define POLY (0x1070U << 3)
2039 static u8 crc8(u16 data)
2043 for (i = 0; i < 8; i++) {
2048 return (u8)(data >> 8);
2051 /* Incremental CRC8 over count bytes in the array pointed to by p */
2052 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
2056 for (i = 0; i < count; i++)
2057 crc = crc8((crc ^ p[i]) << 8);
2061 /* Assume a 7-bit address, which is reasonable for SMBus */
2062 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
2064 /* The address will be sent first */
2065 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
2066 pec = i2c_smbus_pec(pec, &addr, 1);
2068 /* The data buffer follows */
2069 return i2c_smbus_pec(pec, msg->buf, msg->len);
2072 /* Used for write only transactions */
2073 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
2075 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
2079 /* Return <0 on CRC error
2080 If there was a write before this read (most cases) we need to take the
2081 partial CRC from the write part into account.
2082 Note that this function does modify the message (we need to decrease the
2083 message length to hide the CRC byte from the caller). */
2084 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
2086 u8 rpec = msg->buf[--msg->len];
2087 cpec = i2c_smbus_msg_pec(cpec, msg);
2090 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
2098 * i2c_smbus_read_byte - SMBus "receive byte" protocol
2099 * @client: Handle to slave device
2101 * This executes the SMBus "receive byte" protocol, returning negative errno
2102 * else the byte received from the device.
2104 s32 i2c_smbus_read_byte(const struct i2c_client *client)
2106 union i2c_smbus_data data;
2109 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2111 I2C_SMBUS_BYTE, &data);
2112 return (status < 0) ? status : data.byte;
2114 EXPORT_SYMBOL(i2c_smbus_read_byte);
2117 * i2c_smbus_write_byte - SMBus "send byte" protocol
2118 * @client: Handle to slave device
2119 * @value: Byte to be sent
2121 * This executes the SMBus "send byte" protocol, returning negative errno
2122 * else zero on success.
2124 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
2126 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2127 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
2129 EXPORT_SYMBOL(i2c_smbus_write_byte);
2132 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
2133 * @client: Handle to slave device
2134 * @command: Byte interpreted by slave
2136 * This executes the SMBus "read byte" protocol, returning negative errno
2137 * else a data byte received from the device.
2139 s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
2141 union i2c_smbus_data data;
2144 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2145 I2C_SMBUS_READ, command,
2146 I2C_SMBUS_BYTE_DATA, &data);
2147 return (status < 0) ? status : data.byte;
2149 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
2152 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
2153 * @client: Handle to slave device
2154 * @command: Byte interpreted by slave
2155 * @value: Byte being written
2157 * This executes the SMBus "write byte" protocol, returning negative errno
2158 * else zero on success.
2160 s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
2163 union i2c_smbus_data data;
2165 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2166 I2C_SMBUS_WRITE, command,
2167 I2C_SMBUS_BYTE_DATA, &data);
2169 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
2172 * i2c_smbus_read_word_data - SMBus "read word" protocol
2173 * @client: Handle to slave device
2174 * @command: Byte interpreted by slave
2176 * This executes the SMBus "read word" protocol, returning negative errno
2177 * else a 16-bit unsigned "word" received from the device.
2179 s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
2181 union i2c_smbus_data data;
2184 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2185 I2C_SMBUS_READ, command,
2186 I2C_SMBUS_WORD_DATA, &data);
2187 return (status < 0) ? status : data.word;
2189 EXPORT_SYMBOL(i2c_smbus_read_word_data);
2192 * i2c_smbus_write_word_data - SMBus "write word" protocol
2193 * @client: Handle to slave device
2194 * @command: Byte interpreted by slave
2195 * @value: 16-bit "word" being written
2197 * This executes the SMBus "write word" protocol, returning negative errno
2198 * else zero on success.
2200 s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
2203 union i2c_smbus_data data;
2205 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2206 I2C_SMBUS_WRITE, command,
2207 I2C_SMBUS_WORD_DATA, &data);
2209 EXPORT_SYMBOL(i2c_smbus_write_word_data);
2212 * i2c_smbus_read_block_data - SMBus "block read" protocol
2213 * @client: Handle to slave device
2214 * @command: Byte interpreted by slave
2215 * @values: Byte array into which data will be read; big enough to hold
2216 * the data returned by the slave. SMBus allows at most 32 bytes.
2218 * This executes the SMBus "block read" protocol, returning negative errno
2219 * else the number of data bytes in the slave's response.
2221 * Note that using this function requires that the client's adapter support
2222 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
2223 * support this; its emulation through I2C messaging relies on a specific
2224 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
2226 s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
2229 union i2c_smbus_data data;
2232 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2233 I2C_SMBUS_READ, command,
2234 I2C_SMBUS_BLOCK_DATA, &data);
2238 memcpy(values, &data.block[1], data.block[0]);
2239 return data.block[0];
2241 EXPORT_SYMBOL(i2c_smbus_read_block_data);
2244 * i2c_smbus_write_block_data - SMBus "block write" protocol
2245 * @client: Handle to slave device
2246 * @command: Byte interpreted by slave
2247 * @length: Size of data block; SMBus allows at most 32 bytes
2248 * @values: Byte array which will be written.
2250 * This executes the SMBus "block write" protocol, returning negative errno
2251 * else zero on success.
2253 s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
2254 u8 length, const u8 *values)
2256 union i2c_smbus_data data;
2258 if (length > I2C_SMBUS_BLOCK_MAX)
2259 length = I2C_SMBUS_BLOCK_MAX;
2260 data.block[0] = length;
2261 memcpy(&data.block[1], values, length);
2262 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2263 I2C_SMBUS_WRITE, command,
2264 I2C_SMBUS_BLOCK_DATA, &data);
2266 EXPORT_SYMBOL(i2c_smbus_write_block_data);
2268 /* Returns the number of read bytes */
2269 s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
2270 u8 length, u8 *values)
2272 union i2c_smbus_data data;
2275 if (length > I2C_SMBUS_BLOCK_MAX)
2276 length = I2C_SMBUS_BLOCK_MAX;
2277 data.block[0] = length;
2278 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2279 I2C_SMBUS_READ, command,
2280 I2C_SMBUS_I2C_BLOCK_DATA, &data);
2284 memcpy(values, &data.block[1], data.block[0]);
2285 return data.block[0];
2287 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
2289 s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
2290 u8 length, const u8 *values)
2292 union i2c_smbus_data data;
2294 if (length > I2C_SMBUS_BLOCK_MAX)
2295 length = I2C_SMBUS_BLOCK_MAX;
2296 data.block[0] = length;
2297 memcpy(data.block + 1, values, length);
2298 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2299 I2C_SMBUS_WRITE, command,
2300 I2C_SMBUS_I2C_BLOCK_DATA, &data);
2302 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
2304 /* Simulate a SMBus command using the i2c protocol
2305 No checking of parameters is done! */
2306 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
2307 unsigned short flags,
2308 char read_write, u8 command, int size,
2309 union i2c_smbus_data *data)
2311 /* So we need to generate a series of msgs. In the case of writing, we
2312 need to use only one message; when reading, we need two. We initialize
2313 most things with sane defaults, to keep the code below somewhat
2315 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
2316 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
2317 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
2321 struct i2c_msg msg[2] = {
2329 .flags = flags | I2C_M_RD,
2335 msgbuf0[0] = command;
2337 case I2C_SMBUS_QUICK:
2339 /* Special case: The read/write field is used as data */
2340 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
2344 case I2C_SMBUS_BYTE:
2345 if (read_write == I2C_SMBUS_READ) {
2346 /* Special case: only a read! */
2347 msg[0].flags = I2C_M_RD | flags;
2351 case I2C_SMBUS_BYTE_DATA:
2352 if (read_write == I2C_SMBUS_READ)
2356 msgbuf0[1] = data->byte;
2359 case I2C_SMBUS_WORD_DATA:
2360 if (read_write == I2C_SMBUS_READ)
2364 msgbuf0[1] = data->word & 0xff;
2365 msgbuf0[2] = data->word >> 8;
2368 case I2C_SMBUS_PROC_CALL:
2369 num = 2; /* Special case */
2370 read_write = I2C_SMBUS_READ;
2373 msgbuf0[1] = data->word & 0xff;
2374 msgbuf0[2] = data->word >> 8;
2376 case I2C_SMBUS_BLOCK_DATA:
2377 if (read_write == I2C_SMBUS_READ) {
2378 msg[1].flags |= I2C_M_RECV_LEN;
2379 msg[1].len = 1; /* block length will be added by
2380 the underlying bus driver */
2382 msg[0].len = data->block[0] + 2;
2383 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
2384 dev_err(&adapter->dev,
2385 "Invalid block write size %d\n",
2389 for (i = 1; i < msg[0].len; i++)
2390 msgbuf0[i] = data->block[i-1];
2393 case I2C_SMBUS_BLOCK_PROC_CALL:
2394 num = 2; /* Another special case */
2395 read_write = I2C_SMBUS_READ;
2396 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
2397 dev_err(&adapter->dev,
2398 "Invalid block write size %d\n",
2402 msg[0].len = data->block[0] + 2;
2403 for (i = 1; i < msg[0].len; i++)
2404 msgbuf0[i] = data->block[i-1];
2405 msg[1].flags |= I2C_M_RECV_LEN;
2406 msg[1].len = 1; /* block length will be added by
2407 the underlying bus driver */
2409 case I2C_SMBUS_I2C_BLOCK_DATA:
2410 if (read_write == I2C_SMBUS_READ) {
2411 msg[1].len = data->block[0];
2413 msg[0].len = data->block[0] + 1;
2414 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
2415 dev_err(&adapter->dev,
2416 "Invalid block write size %d\n",
2420 for (i = 1; i <= data->block[0]; i++)
2421 msgbuf0[i] = data->block[i];
2425 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
2429 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
2430 && size != I2C_SMBUS_I2C_BLOCK_DATA);
2432 /* Compute PEC if first message is a write */
2433 if (!(msg[0].flags & I2C_M_RD)) {
2434 if (num == 1) /* Write only */
2435 i2c_smbus_add_pec(&msg[0]);
2436 else /* Write followed by read */
2437 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
2439 /* Ask for PEC if last message is a read */
2440 if (msg[num-1].flags & I2C_M_RD)
2444 status = i2c_transfer(adapter, msg, num);
2448 /* Check PEC if last message is a read */
2449 if (i && (msg[num-1].flags & I2C_M_RD)) {
2450 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
2455 if (read_write == I2C_SMBUS_READ)
2457 case I2C_SMBUS_BYTE:
2458 data->byte = msgbuf0[0];
2460 case I2C_SMBUS_BYTE_DATA:
2461 data->byte = msgbuf1[0];
2463 case I2C_SMBUS_WORD_DATA:
2464 case I2C_SMBUS_PROC_CALL:
2465 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
2467 case I2C_SMBUS_I2C_BLOCK_DATA:
2468 for (i = 0; i < data->block[0]; i++)
2469 data->block[i+1] = msgbuf1[i];
2471 case I2C_SMBUS_BLOCK_DATA:
2472 case I2C_SMBUS_BLOCK_PROC_CALL:
2473 for (i = 0; i < msgbuf1[0] + 1; i++)
2474 data->block[i] = msgbuf1[i];
2481 * i2c_smbus_xfer - execute SMBus protocol operations
2482 * @adapter: Handle to I2C bus
2483 * @addr: Address of SMBus slave on that bus
2484 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
2485 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
2486 * @command: Byte interpreted by slave, for protocols which use such bytes
2487 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
2488 * @data: Data to be read or written
2490 * This executes an SMBus protocol operation, and returns a negative
2491 * errno code else zero on success.
2493 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
2494 char read_write, u8 command, int protocol,
2495 union i2c_smbus_data *data)
2497 unsigned long orig_jiffies;
2501 flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB;
2503 if (adapter->algo->smbus_xfer) {
2504 i2c_lock_adapter(adapter);
2506 /* Retry automatically on arbitration loss */
2507 orig_jiffies = jiffies;
2508 for (res = 0, try = 0; try <= adapter->retries; try++) {
2509 res = adapter->algo->smbus_xfer(adapter, addr, flags,
2510 read_write, command,
2514 if (time_after(jiffies,
2515 orig_jiffies + adapter->timeout))
2518 i2c_unlock_adapter(adapter);
2520 if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)
2523 * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't
2524 * implement native support for the SMBus operation.
2528 return i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
2529 command, protocol, data);
2531 EXPORT_SYMBOL(i2c_smbus_xfer);
2533 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2534 MODULE_DESCRIPTION("I2C-Bus main module");
2535 MODULE_LICENSE("GPL");