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> */
28 #include <linux/module.h>
29 #include <linux/kernel.h>
30 #include <linux/delay.h>
31 #include <linux/errno.h>
32 #include <linux/gpio.h>
33 #include <linux/slab.h>
34 #include <linux/i2c.h>
35 #include <linux/init.h>
36 #include <linux/idr.h>
37 #include <linux/mutex.h>
38 #include <linux/of_device.h>
39 #include <linux/completion.h>
40 #include <linux/hardirq.h>
41 #include <linux/irqflags.h>
42 #include <linux/rwsem.h>
43 #include <linux/pm_runtime.h>
44 #include <linux/acpi.h>
45 #include <asm/uaccess.h>
50 /* core_lock protects i2c_adapter_idr, and guarantees
51 that device detection, deletion of detected devices, and attach_adapter
52 calls are serialized */
53 static DEFINE_MUTEX(core_lock);
54 static DEFINE_IDR(i2c_adapter_idr);
56 static struct device_type i2c_client_type;
57 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
59 /* ------------------------------------------------------------------------- */
61 static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
62 const struct i2c_client *client)
65 if (strcmp(client->name, id->name) == 0)
72 static int i2c_device_match(struct device *dev, struct device_driver *drv)
74 struct i2c_client *client = i2c_verify_client(dev);
75 struct i2c_driver *driver;
80 /* Attempt an OF style match */
81 if (of_driver_match_device(dev, drv))
84 /* Then ACPI style match */
85 if (acpi_driver_match_device(dev, drv))
88 driver = to_i2c_driver(drv);
89 /* match on an id table if there is one */
91 return i2c_match_id(driver->id_table, client) != NULL;
97 /* uevent helps with hotplug: modprobe -q $(MODALIAS) */
98 static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
100 struct i2c_client *client = to_i2c_client(dev);
102 if (add_uevent_var(env, "MODALIAS=%s%s",
103 I2C_MODULE_PREFIX, client->name))
105 dev_dbg(dev, "uevent\n");
109 /* i2c bus recovery routines */
110 static int get_scl_gpio_value(struct i2c_adapter *adap)
112 return gpio_get_value(adap->bus_recovery_info->scl_gpio);
115 static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
117 gpio_set_value(adap->bus_recovery_info->scl_gpio, val);
120 static int get_sda_gpio_value(struct i2c_adapter *adap)
122 return gpio_get_value(adap->bus_recovery_info->sda_gpio);
125 static int i2c_get_gpios_for_recovery(struct i2c_adapter *adap)
127 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
128 struct device *dev = &adap->dev;
131 ret = gpio_request_one(bri->scl_gpio, GPIOF_OPEN_DRAIN |
132 GPIOF_OUT_INIT_HIGH, "i2c-scl");
134 dev_warn(dev, "Can't get SCL gpio: %d\n", bri->scl_gpio);
139 if (gpio_request_one(bri->sda_gpio, GPIOF_IN, "i2c-sda")) {
140 /* work without SDA polling */
141 dev_warn(dev, "Can't get SDA gpio: %d. Not using SDA polling\n",
150 static void i2c_put_gpios_for_recovery(struct i2c_adapter *adap)
152 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
155 gpio_free(bri->sda_gpio);
157 gpio_free(bri->scl_gpio);
161 * We are generating clock pulses. ndelay() determines durating of clk pulses.
162 * We will generate clock with rate 100 KHz and so duration of both clock levels
163 * is: delay in ns = (10^6 / 100) / 2
165 #define RECOVERY_NDELAY 5000
166 #define RECOVERY_CLK_CNT 9
168 static int i2c_generic_recovery(struct i2c_adapter *adap)
170 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
171 int i = 0, val = 1, ret = 0;
173 if (bri->prepare_recovery)
174 bri->prepare_recovery(bri);
177 * By this time SCL is high, as we need to give 9 falling-rising edges
179 while (i++ < RECOVERY_CLK_CNT * 2) {
181 /* Break if SDA is high */
182 if (bri->get_sda && bri->get_sda(adap))
184 /* SCL shouldn't be low here */
185 if (!bri->get_scl(adap)) {
187 "SCL is stuck low, exit recovery\n");
194 bri->set_scl(adap, val);
195 ndelay(RECOVERY_NDELAY);
198 if (bri->unprepare_recovery)
199 bri->unprepare_recovery(bri);
204 int i2c_generic_scl_recovery(struct i2c_adapter *adap)
206 adap->bus_recovery_info->set_scl(adap, 1);
207 return i2c_generic_recovery(adap);
210 int i2c_generic_gpio_recovery(struct i2c_adapter *adap)
214 ret = i2c_get_gpios_for_recovery(adap);
218 ret = i2c_generic_recovery(adap);
219 i2c_put_gpios_for_recovery(adap);
224 int i2c_recover_bus(struct i2c_adapter *adap)
226 if (!adap->bus_recovery_info)
229 dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
230 return adap->bus_recovery_info->recover_bus(adap);
233 static int i2c_device_probe(struct device *dev)
235 struct i2c_client *client = i2c_verify_client(dev);
236 struct i2c_driver *driver;
242 driver = to_i2c_driver(dev->driver);
243 if (!driver->probe || !driver->id_table)
245 client->driver = driver;
246 if (!device_can_wakeup(&client->dev))
247 device_init_wakeup(&client->dev,
248 client->flags & I2C_CLIENT_WAKE);
249 dev_dbg(dev, "probe\n");
251 status = driver->probe(client, i2c_match_id(driver->id_table, client));
253 client->driver = NULL;
254 i2c_set_clientdata(client, NULL);
259 static int i2c_device_remove(struct device *dev)
261 struct i2c_client *client = i2c_verify_client(dev);
262 struct i2c_driver *driver;
265 if (!client || !dev->driver)
268 driver = to_i2c_driver(dev->driver);
269 if (driver->remove) {
270 dev_dbg(dev, "remove\n");
271 status = driver->remove(client);
277 client->driver = NULL;
278 i2c_set_clientdata(client, NULL);
283 static void i2c_device_shutdown(struct device *dev)
285 struct i2c_client *client = i2c_verify_client(dev);
286 struct i2c_driver *driver;
288 if (!client || !dev->driver)
290 driver = to_i2c_driver(dev->driver);
291 if (driver->shutdown)
292 driver->shutdown(client);
295 #ifdef CONFIG_PM_SLEEP
296 static int i2c_legacy_suspend(struct device *dev, pm_message_t mesg)
298 struct i2c_client *client = i2c_verify_client(dev);
299 struct i2c_driver *driver;
301 if (!client || !dev->driver)
303 driver = to_i2c_driver(dev->driver);
304 if (!driver->suspend)
306 return driver->suspend(client, mesg);
309 static int i2c_legacy_resume(struct device *dev)
311 struct i2c_client *client = i2c_verify_client(dev);
312 struct i2c_driver *driver;
314 if (!client || !dev->driver)
316 driver = to_i2c_driver(dev->driver);
319 return driver->resume(client);
322 static int i2c_device_pm_suspend(struct device *dev)
324 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
327 return pm_generic_suspend(dev);
329 return i2c_legacy_suspend(dev, PMSG_SUSPEND);
332 static int i2c_device_pm_resume(struct device *dev)
334 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
337 return pm_generic_resume(dev);
339 return i2c_legacy_resume(dev);
342 static int i2c_device_pm_freeze(struct device *dev)
344 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
347 return pm_generic_freeze(dev);
349 return i2c_legacy_suspend(dev, PMSG_FREEZE);
352 static int i2c_device_pm_thaw(struct device *dev)
354 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
357 return pm_generic_thaw(dev);
359 return i2c_legacy_resume(dev);
362 static int i2c_device_pm_poweroff(struct device *dev)
364 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
367 return pm_generic_poweroff(dev);
369 return i2c_legacy_suspend(dev, PMSG_HIBERNATE);
372 static int i2c_device_pm_restore(struct device *dev)
374 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
377 return pm_generic_restore(dev);
379 return i2c_legacy_resume(dev);
381 #else /* !CONFIG_PM_SLEEP */
382 #define i2c_device_pm_suspend NULL
383 #define i2c_device_pm_resume NULL
384 #define i2c_device_pm_freeze NULL
385 #define i2c_device_pm_thaw NULL
386 #define i2c_device_pm_poweroff NULL
387 #define i2c_device_pm_restore NULL
388 #endif /* !CONFIG_PM_SLEEP */
390 static void i2c_client_dev_release(struct device *dev)
392 kfree(to_i2c_client(dev));
396 show_name(struct device *dev, struct device_attribute *attr, char *buf)
398 return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
399 to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
403 show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
405 struct i2c_client *client = to_i2c_client(dev);
406 return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
409 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
410 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
412 static struct attribute *i2c_dev_attrs[] = {
414 /* modalias helps coldplug: modprobe $(cat .../modalias) */
415 &dev_attr_modalias.attr,
419 static struct attribute_group i2c_dev_attr_group = {
420 .attrs = i2c_dev_attrs,
423 static const struct attribute_group *i2c_dev_attr_groups[] = {
428 static const struct dev_pm_ops i2c_device_pm_ops = {
429 .suspend = i2c_device_pm_suspend,
430 .resume = i2c_device_pm_resume,
431 .freeze = i2c_device_pm_freeze,
432 .thaw = i2c_device_pm_thaw,
433 .poweroff = i2c_device_pm_poweroff,
434 .restore = i2c_device_pm_restore,
436 pm_generic_runtime_suspend,
437 pm_generic_runtime_resume,
438 pm_generic_runtime_idle
442 struct bus_type i2c_bus_type = {
444 .match = i2c_device_match,
445 .probe = i2c_device_probe,
446 .remove = i2c_device_remove,
447 .shutdown = i2c_device_shutdown,
448 .pm = &i2c_device_pm_ops,
450 EXPORT_SYMBOL_GPL(i2c_bus_type);
452 static struct device_type i2c_client_type = {
453 .groups = i2c_dev_attr_groups,
454 .uevent = i2c_device_uevent,
455 .release = i2c_client_dev_release,
460 * i2c_verify_client - return parameter as i2c_client, or NULL
461 * @dev: device, probably from some driver model iterator
463 * When traversing the driver model tree, perhaps using driver model
464 * iterators like @device_for_each_child(), you can't assume very much
465 * about the nodes you find. Use this function to avoid oopses caused
466 * by wrongly treating some non-I2C device as an i2c_client.
468 struct i2c_client *i2c_verify_client(struct device *dev)
470 return (dev->type == &i2c_client_type)
474 EXPORT_SYMBOL(i2c_verify_client);
477 /* This is a permissive address validity check, I2C address map constraints
478 * are purposely not enforced, except for the general call address. */
479 static int i2c_check_client_addr_validity(const struct i2c_client *client)
481 if (client->flags & I2C_CLIENT_TEN) {
482 /* 10-bit address, all values are valid */
483 if (client->addr > 0x3ff)
486 /* 7-bit address, reject the general call address */
487 if (client->addr == 0x00 || client->addr > 0x7f)
493 /* And this is a strict address validity check, used when probing. If a
494 * device uses a reserved address, then it shouldn't be probed. 7-bit
495 * addressing is assumed, 10-bit address devices are rare and should be
496 * explicitly enumerated. */
497 static int i2c_check_addr_validity(unsigned short addr)
500 * Reserved addresses per I2C specification:
501 * 0x00 General call address / START byte
503 * 0x02 Reserved for different bus format
504 * 0x03 Reserved for future purposes
505 * 0x04-0x07 Hs-mode master code
506 * 0x78-0x7b 10-bit slave addressing
507 * 0x7c-0x7f Reserved for future purposes
509 if (addr < 0x08 || addr > 0x77)
514 static int __i2c_check_addr_busy(struct device *dev, void *addrp)
516 struct i2c_client *client = i2c_verify_client(dev);
517 int addr = *(int *)addrp;
519 if (client && client->addr == addr)
524 /* walk up mux tree */
525 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
527 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
530 result = device_for_each_child(&adapter->dev, &addr,
531 __i2c_check_addr_busy);
533 if (!result && parent)
534 result = i2c_check_mux_parents(parent, addr);
539 /* recurse down mux tree */
540 static int i2c_check_mux_children(struct device *dev, void *addrp)
544 if (dev->type == &i2c_adapter_type)
545 result = device_for_each_child(dev, addrp,
546 i2c_check_mux_children);
548 result = __i2c_check_addr_busy(dev, addrp);
553 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
555 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
559 result = i2c_check_mux_parents(parent, addr);
562 result = device_for_each_child(&adapter->dev, &addr,
563 i2c_check_mux_children);
569 * i2c_lock_adapter - Get exclusive access to an I2C bus segment
570 * @adapter: Target I2C bus segment
572 void i2c_lock_adapter(struct i2c_adapter *adapter)
574 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
577 i2c_lock_adapter(parent);
579 rt_mutex_lock(&adapter->bus_lock);
581 EXPORT_SYMBOL_GPL(i2c_lock_adapter);
584 * i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment
585 * @adapter: Target I2C bus segment
587 static int i2c_trylock_adapter(struct i2c_adapter *adapter)
589 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
592 return i2c_trylock_adapter(parent);
594 return rt_mutex_trylock(&adapter->bus_lock);
598 * i2c_unlock_adapter - Release exclusive access to an I2C bus segment
599 * @adapter: Target I2C bus segment
601 void i2c_unlock_adapter(struct i2c_adapter *adapter)
603 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
606 i2c_unlock_adapter(parent);
608 rt_mutex_unlock(&adapter->bus_lock);
610 EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
613 * i2c_new_device - instantiate an i2c device
614 * @adap: the adapter managing the device
615 * @info: describes one I2C device; bus_num is ignored
618 * Create an i2c device. Binding is handled through driver model
619 * probe()/remove() methods. A driver may be bound to this device when we
620 * return from this function, or any later moment (e.g. maybe hotplugging will
621 * load the driver module). This call is not appropriate for use by mainboard
622 * initialization logic, which usually runs during an arch_initcall() long
623 * before any i2c_adapter could exist.
625 * This returns the new i2c client, which may be saved for later use with
626 * i2c_unregister_device(); or NULL to indicate an error.
629 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
631 struct i2c_client *client;
634 client = kzalloc(sizeof *client, GFP_KERNEL);
638 client->adapter = adap;
640 client->dev.platform_data = info->platform_data;
643 client->dev.archdata = *info->archdata;
645 client->flags = info->flags;
646 client->addr = info->addr;
647 client->irq = info->irq;
649 strlcpy(client->name, info->type, sizeof(client->name));
651 /* Check for address validity */
652 status = i2c_check_client_addr_validity(client);
654 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
655 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
659 /* Check for address business */
660 status = i2c_check_addr_busy(adap, client->addr);
664 client->dev.parent = &client->adapter->dev;
665 client->dev.bus = &i2c_bus_type;
666 client->dev.type = &i2c_client_type;
667 client->dev.of_node = info->of_node;
668 ACPI_HANDLE_SET(&client->dev, info->acpi_node.handle);
670 /* For 10-bit clients, add an arbitrary offset to avoid collisions */
671 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
672 client->addr | ((client->flags & I2C_CLIENT_TEN)
674 status = device_register(&client->dev);
678 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
679 client->name, dev_name(&client->dev));
684 dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
685 "(%d)\n", client->name, client->addr, status);
690 EXPORT_SYMBOL_GPL(i2c_new_device);
694 * i2c_unregister_device - reverse effect of i2c_new_device()
695 * @client: value returned from i2c_new_device()
698 void i2c_unregister_device(struct i2c_client *client)
700 device_unregister(&client->dev);
702 EXPORT_SYMBOL_GPL(i2c_unregister_device);
705 static const struct i2c_device_id dummy_id[] = {
710 static int dummy_probe(struct i2c_client *client,
711 const struct i2c_device_id *id)
716 static int dummy_remove(struct i2c_client *client)
721 static struct i2c_driver dummy_driver = {
722 .driver.name = "dummy",
723 .probe = dummy_probe,
724 .remove = dummy_remove,
725 .id_table = dummy_id,
729 * i2c_new_dummy - return a new i2c device bound to a dummy driver
730 * @adapter: the adapter managing the device
731 * @address: seven bit address to be used
734 * This returns an I2C client bound to the "dummy" driver, intended for use
735 * with devices that consume multiple addresses. Examples of such chips
736 * include various EEPROMS (like 24c04 and 24c08 models).
738 * These dummy devices have two main uses. First, most I2C and SMBus calls
739 * except i2c_transfer() need a client handle; the dummy will be that handle.
740 * And second, this prevents the specified address from being bound to a
743 * This returns the new i2c client, which should be saved for later use with
744 * i2c_unregister_device(); or NULL to indicate an error.
746 struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
748 struct i2c_board_info info = {
749 I2C_BOARD_INFO("dummy", address),
752 return i2c_new_device(adapter, &info);
754 EXPORT_SYMBOL_GPL(i2c_new_dummy);
756 /* ------------------------------------------------------------------------- */
758 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
760 static void i2c_adapter_dev_release(struct device *dev)
762 struct i2c_adapter *adap = to_i2c_adapter(dev);
763 complete(&adap->dev_released);
767 * This function is only needed for mutex_lock_nested, so it is never
768 * called unless locking correctness checking is enabled. Thus we
769 * make it inline to avoid a compiler warning. That's what gcc ends up
772 static inline unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
774 unsigned int depth = 0;
776 while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
783 * Let users instantiate I2C devices through sysfs. This can be used when
784 * platform initialization code doesn't contain the proper data for
785 * whatever reason. Also useful for drivers that do device detection and
786 * detection fails, either because the device uses an unexpected address,
787 * or this is a compatible device with different ID register values.
789 * Parameter checking may look overzealous, but we really don't want
790 * the user to provide incorrect parameters.
793 i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
794 const char *buf, size_t count)
796 struct i2c_adapter *adap = to_i2c_adapter(dev);
797 struct i2c_board_info info;
798 struct i2c_client *client;
802 memset(&info, 0, sizeof(struct i2c_board_info));
804 blank = strchr(buf, ' ');
806 dev_err(dev, "%s: Missing parameters\n", "new_device");
809 if (blank - buf > I2C_NAME_SIZE - 1) {
810 dev_err(dev, "%s: Invalid device name\n", "new_device");
813 memcpy(info.type, buf, blank - buf);
815 /* Parse remaining parameters, reject extra parameters */
816 res = sscanf(++blank, "%hi%c", &info.addr, &end);
818 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
821 if (res > 1 && end != '\n') {
822 dev_err(dev, "%s: Extra parameters\n", "new_device");
826 client = i2c_new_device(adap, &info);
830 /* Keep track of the added device */
831 mutex_lock(&adap->userspace_clients_lock);
832 list_add_tail(&client->detected, &adap->userspace_clients);
833 mutex_unlock(&adap->userspace_clients_lock);
834 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
835 info.type, info.addr);
841 * And of course let the users delete the devices they instantiated, if
842 * they got it wrong. This interface can only be used to delete devices
843 * instantiated by i2c_sysfs_new_device above. This guarantees that we
844 * don't delete devices to which some kernel code still has references.
846 * Parameter checking may look overzealous, but we really don't want
847 * the user to delete the wrong device.
850 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
851 const char *buf, size_t count)
853 struct i2c_adapter *adap = to_i2c_adapter(dev);
854 struct i2c_client *client, *next;
859 /* Parse parameters, reject extra parameters */
860 res = sscanf(buf, "%hi%c", &addr, &end);
862 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
865 if (res > 1 && end != '\n') {
866 dev_err(dev, "%s: Extra parameters\n", "delete_device");
870 /* Make sure the device was added through sysfs */
872 mutex_lock_nested(&adap->userspace_clients_lock,
873 i2c_adapter_depth(adap));
874 list_for_each_entry_safe(client, next, &adap->userspace_clients,
876 if (client->addr == addr) {
877 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
878 "delete_device", client->name, client->addr);
880 list_del(&client->detected);
881 i2c_unregister_device(client);
886 mutex_unlock(&adap->userspace_clients_lock);
889 dev_err(dev, "%s: Can't find device in list\n",
894 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
895 static DEVICE_ATTR(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device);
897 static struct attribute *i2c_adapter_attrs[] = {
899 &dev_attr_new_device.attr,
900 &dev_attr_delete_device.attr,
904 static struct attribute_group i2c_adapter_attr_group = {
905 .attrs = i2c_adapter_attrs,
908 static const struct attribute_group *i2c_adapter_attr_groups[] = {
909 &i2c_adapter_attr_group,
913 struct device_type i2c_adapter_type = {
914 .groups = i2c_adapter_attr_groups,
915 .release = i2c_adapter_dev_release,
917 EXPORT_SYMBOL_GPL(i2c_adapter_type);
920 * i2c_verify_adapter - return parameter as i2c_adapter or NULL
921 * @dev: device, probably from some driver model iterator
923 * When traversing the driver model tree, perhaps using driver model
924 * iterators like @device_for_each_child(), you can't assume very much
925 * about the nodes you find. Use this function to avoid oopses caused
926 * by wrongly treating some non-I2C device as an i2c_adapter.
928 struct i2c_adapter *i2c_verify_adapter(struct device *dev)
930 return (dev->type == &i2c_adapter_type)
931 ? to_i2c_adapter(dev)
934 EXPORT_SYMBOL(i2c_verify_adapter);
936 #ifdef CONFIG_I2C_COMPAT
937 static struct class_compat *i2c_adapter_compat_class;
940 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
942 struct i2c_devinfo *devinfo;
944 down_read(&__i2c_board_lock);
945 list_for_each_entry(devinfo, &__i2c_board_list, list) {
946 if (devinfo->busnum == adapter->nr
947 && !i2c_new_device(adapter,
948 &devinfo->board_info))
949 dev_err(&adapter->dev,
950 "Can't create device at 0x%02x\n",
951 devinfo->board_info.addr);
953 up_read(&__i2c_board_lock);
956 static int i2c_do_add_adapter(struct i2c_driver *driver,
957 struct i2c_adapter *adap)
959 /* Detect supported devices on that bus, and instantiate them */
960 i2c_detect(adap, driver);
962 /* Let legacy drivers scan this bus for matching devices */
963 if (driver->attach_adapter) {
964 dev_warn(&adap->dev, "%s: attach_adapter method is deprecated\n",
965 driver->driver.name);
966 dev_warn(&adap->dev, "Please use another way to instantiate "
967 "your i2c_client\n");
968 /* We ignore the return code; if it fails, too bad */
969 driver->attach_adapter(adap);
974 static int __process_new_adapter(struct device_driver *d, void *data)
976 return i2c_do_add_adapter(to_i2c_driver(d), data);
979 static int i2c_register_adapter(struct i2c_adapter *adap)
983 /* Can't register until after driver model init */
984 if (unlikely(WARN_ON(!i2c_bus_type.p))) {
990 if (unlikely(adap->name[0] == '\0')) {
991 pr_err("i2c-core: Attempt to register an adapter with "
995 if (unlikely(!adap->algo)) {
996 pr_err("i2c-core: Attempt to register adapter '%s' with "
997 "no algo!\n", adap->name);
1001 rt_mutex_init(&adap->bus_lock);
1002 mutex_init(&adap->userspace_clients_lock);
1003 INIT_LIST_HEAD(&adap->userspace_clients);
1005 /* Set default timeout to 1 second if not already set */
1006 if (adap->timeout == 0)
1009 dev_set_name(&adap->dev, "i2c-%d", adap->nr);
1010 adap->dev.bus = &i2c_bus_type;
1011 adap->dev.type = &i2c_adapter_type;
1012 res = device_register(&adap->dev);
1016 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1018 #ifdef CONFIG_I2C_COMPAT
1019 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
1022 dev_warn(&adap->dev,
1023 "Failed to create compatibility class link\n");
1026 /* bus recovery specific initialization */
1027 if (adap->bus_recovery_info) {
1028 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
1030 if (!bri->recover_bus) {
1031 dev_err(&adap->dev, "No recover_bus() found, not using recovery\n");
1032 adap->bus_recovery_info = NULL;
1036 /* Generic GPIO recovery */
1037 if (bri->recover_bus == i2c_generic_gpio_recovery) {
1038 if (!gpio_is_valid(bri->scl_gpio)) {
1039 dev_err(&adap->dev, "Invalid SCL gpio, not using recovery\n");
1040 adap->bus_recovery_info = NULL;
1044 if (gpio_is_valid(bri->sda_gpio))
1045 bri->get_sda = get_sda_gpio_value;
1047 bri->get_sda = NULL;
1049 bri->get_scl = get_scl_gpio_value;
1050 bri->set_scl = set_scl_gpio_value;
1051 } else if (!bri->set_scl || !bri->get_scl) {
1052 /* Generic SCL recovery */
1053 dev_err(&adap->dev, "No {get|set}_gpio() found, not using recovery\n");
1054 adap->bus_recovery_info = NULL;
1059 /* create pre-declared device nodes */
1060 if (adap->nr < __i2c_first_dynamic_bus_num)
1061 i2c_scan_static_board_info(adap);
1063 /* Notify drivers */
1064 mutex_lock(&core_lock);
1065 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
1066 mutex_unlock(&core_lock);
1071 mutex_lock(&core_lock);
1072 idr_remove(&i2c_adapter_idr, adap->nr);
1073 mutex_unlock(&core_lock);
1078 * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1079 * @adap: the adapter to register (with adap->nr initialized)
1080 * Context: can sleep
1082 * See i2c_add_numbered_adapter() for details.
1084 static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1088 mutex_lock(&core_lock);
1089 id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,
1091 mutex_unlock(&core_lock);
1093 return id == -ENOSPC ? -EBUSY : id;
1095 return i2c_register_adapter(adap);
1099 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
1100 * @adapter: the adapter to add
1101 * Context: can sleep
1103 * This routine is used to declare an I2C adapter when its bus number
1104 * doesn't matter or when its bus number is specified by an dt alias.
1105 * Examples of bases when the bus number doesn't matter: I2C adapters
1106 * dynamically added by USB links or PCI plugin cards.
1108 * When this returns zero, a new bus number was allocated and stored
1109 * in adap->nr, and the specified adapter became available for clients.
1110 * Otherwise, a negative errno value is returned.
1112 int i2c_add_adapter(struct i2c_adapter *adapter)
1114 struct device *dev = &adapter->dev;
1118 id = of_alias_get_id(dev->of_node, "i2c");
1121 return __i2c_add_numbered_adapter(adapter);
1125 mutex_lock(&core_lock);
1126 id = idr_alloc(&i2c_adapter_idr, adapter,
1127 __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
1128 mutex_unlock(&core_lock);
1134 return i2c_register_adapter(adapter);
1136 EXPORT_SYMBOL(i2c_add_adapter);
1139 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1140 * @adap: the adapter to register (with adap->nr initialized)
1141 * Context: can sleep
1143 * This routine is used to declare an I2C adapter when its bus number
1144 * matters. For example, use it for I2C adapters from system-on-chip CPUs,
1145 * or otherwise built in to the system's mainboard, and where i2c_board_info
1146 * is used to properly configure I2C devices.
1148 * If the requested bus number is set to -1, then this function will behave
1149 * identically to i2c_add_adapter, and will dynamically assign a bus number.
1151 * If no devices have pre-been declared for this bus, then be sure to
1152 * register the adapter before any dynamically allocated ones. Otherwise
1153 * the required bus ID may not be available.
1155 * When this returns zero, the specified adapter became available for
1156 * clients using the bus number provided in adap->nr. Also, the table
1157 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
1158 * and the appropriate driver model device nodes are created. Otherwise, a
1159 * negative errno value is returned.
1161 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1163 if (adap->nr == -1) /* -1 means dynamically assign bus id */
1164 return i2c_add_adapter(adap);
1166 return __i2c_add_numbered_adapter(adap);
1168 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1170 static void i2c_do_del_adapter(struct i2c_driver *driver,
1171 struct i2c_adapter *adapter)
1173 struct i2c_client *client, *_n;
1175 /* Remove the devices we created ourselves as the result of hardware
1176 * probing (using a driver's detect method) */
1177 list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1178 if (client->adapter == adapter) {
1179 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1180 client->name, client->addr);
1181 list_del(&client->detected);
1182 i2c_unregister_device(client);
1187 static int __unregister_client(struct device *dev, void *dummy)
1189 struct i2c_client *client = i2c_verify_client(dev);
1190 if (client && strcmp(client->name, "dummy"))
1191 i2c_unregister_device(client);
1195 static int __unregister_dummy(struct device *dev, void *dummy)
1197 struct i2c_client *client = i2c_verify_client(dev);
1199 i2c_unregister_device(client);
1203 static int __process_removed_adapter(struct device_driver *d, void *data)
1205 i2c_do_del_adapter(to_i2c_driver(d), data);
1210 * i2c_del_adapter - unregister I2C adapter
1211 * @adap: the adapter being unregistered
1212 * Context: can sleep
1214 * This unregisters an I2C adapter which was previously registered
1215 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1217 void i2c_del_adapter(struct i2c_adapter *adap)
1219 struct i2c_adapter *found;
1220 struct i2c_client *client, *next;
1222 /* First make sure that this adapter was ever added */
1223 mutex_lock(&core_lock);
1224 found = idr_find(&i2c_adapter_idr, adap->nr);
1225 mutex_unlock(&core_lock);
1226 if (found != adap) {
1227 pr_debug("i2c-core: attempting to delete unregistered "
1228 "adapter [%s]\n", adap->name);
1232 /* Tell drivers about this removal */
1233 mutex_lock(&core_lock);
1234 bus_for_each_drv(&i2c_bus_type, NULL, adap,
1235 __process_removed_adapter);
1236 mutex_unlock(&core_lock);
1238 /* Remove devices instantiated from sysfs */
1239 mutex_lock_nested(&adap->userspace_clients_lock,
1240 i2c_adapter_depth(adap));
1241 list_for_each_entry_safe(client, next, &adap->userspace_clients,
1243 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1245 list_del(&client->detected);
1246 i2c_unregister_device(client);
1248 mutex_unlock(&adap->userspace_clients_lock);
1250 /* Detach any active clients. This can't fail, thus we do not
1251 * check the returned value. This is a two-pass process, because
1252 * we can't remove the dummy devices during the first pass: they
1253 * could have been instantiated by real devices wishing to clean
1254 * them up properly, so we give them a chance to do that first. */
1255 device_for_each_child(&adap->dev, NULL, __unregister_client);
1256 device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1258 #ifdef CONFIG_I2C_COMPAT
1259 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1263 /* device name is gone after device_unregister */
1264 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1266 /* clean up the sysfs representation */
1267 init_completion(&adap->dev_released);
1268 device_unregister(&adap->dev);
1270 /* wait for sysfs to drop all references */
1271 wait_for_completion(&adap->dev_released);
1274 mutex_lock(&core_lock);
1275 idr_remove(&i2c_adapter_idr, adap->nr);
1276 mutex_unlock(&core_lock);
1278 /* Clear the device structure in case this adapter is ever going to be
1280 memset(&adap->dev, 0, sizeof(adap->dev));
1282 EXPORT_SYMBOL(i2c_del_adapter);
1285 /* ------------------------------------------------------------------------- */
1287 int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *))
1291 mutex_lock(&core_lock);
1292 res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
1293 mutex_unlock(&core_lock);
1297 EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1299 static int __process_new_driver(struct device *dev, void *data)
1301 if (dev->type != &i2c_adapter_type)
1303 return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1307 * An i2c_driver is used with one or more i2c_client (device) nodes to access
1308 * i2c slave chips, on a bus instance associated with some i2c_adapter.
1311 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1315 /* Can't register until after driver model init */
1316 if (unlikely(WARN_ON(!i2c_bus_type.p)))
1319 /* add the driver to the list of i2c drivers in the driver core */
1320 driver->driver.owner = owner;
1321 driver->driver.bus = &i2c_bus_type;
1323 /* When registration returns, the driver core
1324 * will have called probe() for all matching-but-unbound devices.
1326 res = driver_register(&driver->driver);
1330 /* Drivers should switch to dev_pm_ops instead. */
1331 if (driver->suspend)
1332 pr_warn("i2c-core: driver [%s] using legacy suspend method\n",
1333 driver->driver.name);
1335 pr_warn("i2c-core: driver [%s] using legacy resume method\n",
1336 driver->driver.name);
1338 pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
1340 INIT_LIST_HEAD(&driver->clients);
1341 /* Walk the adapters that are already present */
1342 i2c_for_each_dev(driver, __process_new_driver);
1346 EXPORT_SYMBOL(i2c_register_driver);
1348 static int __process_removed_driver(struct device *dev, void *data)
1350 if (dev->type == &i2c_adapter_type)
1351 i2c_do_del_adapter(data, to_i2c_adapter(dev));
1356 * i2c_del_driver - unregister I2C driver
1357 * @driver: the driver being unregistered
1358 * Context: can sleep
1360 void i2c_del_driver(struct i2c_driver *driver)
1362 i2c_for_each_dev(driver, __process_removed_driver);
1364 driver_unregister(&driver->driver);
1365 pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
1367 EXPORT_SYMBOL(i2c_del_driver);
1369 /* ------------------------------------------------------------------------- */
1372 * i2c_use_client - increments the reference count of the i2c client structure
1373 * @client: the client being referenced
1375 * Each live reference to a client should be refcounted. The driver model does
1376 * that automatically as part of driver binding, so that most drivers don't
1377 * need to do this explicitly: they hold a reference until they're unbound
1380 * A pointer to the client with the incremented reference counter is returned.
1382 struct i2c_client *i2c_use_client(struct i2c_client *client)
1384 if (client && get_device(&client->dev))
1388 EXPORT_SYMBOL(i2c_use_client);
1391 * i2c_release_client - release a use of the i2c client structure
1392 * @client: the client being no longer referenced
1394 * Must be called when a user of a client is finished with it.
1396 void i2c_release_client(struct i2c_client *client)
1399 put_device(&client->dev);
1401 EXPORT_SYMBOL(i2c_release_client);
1403 struct i2c_cmd_arg {
1408 static int i2c_cmd(struct device *dev, void *_arg)
1410 struct i2c_client *client = i2c_verify_client(dev);
1411 struct i2c_cmd_arg *arg = _arg;
1413 if (client && client->driver && client->driver->command)
1414 client->driver->command(client, arg->cmd, arg->arg);
1418 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1420 struct i2c_cmd_arg cmd_arg;
1424 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1426 EXPORT_SYMBOL(i2c_clients_command);
1428 static int __init i2c_init(void)
1432 retval = bus_register(&i2c_bus_type);
1435 #ifdef CONFIG_I2C_COMPAT
1436 i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1437 if (!i2c_adapter_compat_class) {
1442 retval = i2c_add_driver(&dummy_driver);
1448 #ifdef CONFIG_I2C_COMPAT
1449 class_compat_unregister(i2c_adapter_compat_class);
1452 bus_unregister(&i2c_bus_type);
1456 static void __exit i2c_exit(void)
1458 i2c_del_driver(&dummy_driver);
1459 #ifdef CONFIG_I2C_COMPAT
1460 class_compat_unregister(i2c_adapter_compat_class);
1462 bus_unregister(&i2c_bus_type);
1465 /* We must initialize early, because some subsystems register i2c drivers
1466 * in subsys_initcall() code, but are linked (and initialized) before i2c.
1468 postcore_initcall(i2c_init);
1469 module_exit(i2c_exit);
1471 /* ----------------------------------------------------
1472 * the functional interface to the i2c busses.
1473 * ----------------------------------------------------
1477 * __i2c_transfer - unlocked flavor of i2c_transfer
1478 * @adap: Handle to I2C bus
1479 * @msgs: One or more messages to execute before STOP is issued to
1480 * terminate the operation; each message begins with a START.
1481 * @num: Number of messages to be executed.
1483 * Returns negative errno, else the number of messages executed.
1485 * Adapter lock must be held when calling this function. No debug logging
1486 * takes place. adap->algo->master_xfer existence isn't checked.
1488 int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1490 unsigned long orig_jiffies;
1493 /* Retry automatically on arbitration loss */
1494 orig_jiffies = jiffies;
1495 for (ret = 0, try = 0; try <= adap->retries; try++) {
1496 ret = adap->algo->master_xfer(adap, msgs, num);
1499 if (time_after(jiffies, orig_jiffies + adap->timeout))
1505 EXPORT_SYMBOL(__i2c_transfer);
1508 * i2c_transfer - execute a single or combined I2C message
1509 * @adap: Handle to I2C bus
1510 * @msgs: One or more messages to execute before STOP is issued to
1511 * terminate the operation; each message begins with a START.
1512 * @num: Number of messages to be executed.
1514 * Returns negative errno, else the number of messages executed.
1516 * Note that there is no requirement that each message be sent to
1517 * the same slave address, although that is the most common model.
1519 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1523 /* REVISIT the fault reporting model here is weak:
1525 * - When we get an error after receiving N bytes from a slave,
1526 * there is no way to report "N".
1528 * - When we get a NAK after transmitting N bytes to a slave,
1529 * there is no way to report "N" ... or to let the master
1530 * continue executing the rest of this combined message, if
1531 * that's the appropriate response.
1533 * - When for example "num" is two and we successfully complete
1534 * the first message but get an error part way through the
1535 * second, it's unclear whether that should be reported as
1536 * one (discarding status on the second message) or errno
1537 * (discarding status on the first one).
1540 if (adap->algo->master_xfer) {
1542 for (ret = 0; ret < num; ret++) {
1543 dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
1544 "len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
1545 ? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
1546 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1550 if (in_atomic() || irqs_disabled()) {
1551 ret = i2c_trylock_adapter(adap);
1553 /* I2C activity is ongoing. */
1556 i2c_lock_adapter(adap);
1559 ret = __i2c_transfer(adap, msgs, num);
1560 i2c_unlock_adapter(adap);
1564 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1568 EXPORT_SYMBOL(i2c_transfer);
1571 * i2c_master_send - issue a single I2C message in master transmit mode
1572 * @client: Handle to slave device
1573 * @buf: Data that will be written to the slave
1574 * @count: How many bytes to write, must be less than 64k since msg.len is u16
1576 * Returns negative errno, or else the number of bytes written.
1578 int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
1581 struct i2c_adapter *adap = client->adapter;
1584 msg.addr = client->addr;
1585 msg.flags = client->flags & I2C_M_TEN;
1587 msg.buf = (char *)buf;
1589 ret = i2c_transfer(adap, &msg, 1);
1592 * If everything went ok (i.e. 1 msg transmitted), return #bytes
1593 * transmitted, else error code.
1595 return (ret == 1) ? count : ret;
1597 EXPORT_SYMBOL(i2c_master_send);
1600 * i2c_master_recv - issue a single I2C message in master receive mode
1601 * @client: Handle to slave device
1602 * @buf: Where to store data read from slave
1603 * @count: How many bytes to read, must be less than 64k since msg.len is u16
1605 * Returns negative errno, or else the number of bytes read.
1607 int i2c_master_recv(const struct i2c_client *client, char *buf, int count)
1609 struct i2c_adapter *adap = client->adapter;
1613 msg.addr = client->addr;
1614 msg.flags = client->flags & I2C_M_TEN;
1615 msg.flags |= I2C_M_RD;
1619 ret = i2c_transfer(adap, &msg, 1);
1622 * If everything went ok (i.e. 1 msg received), return #bytes received,
1625 return (ret == 1) ? count : ret;
1627 EXPORT_SYMBOL(i2c_master_recv);
1629 /* ----------------------------------------------------
1630 * the i2c address scanning function
1631 * Will not work for 10-bit addresses!
1632 * ----------------------------------------------------
1636 * Legacy default probe function, mostly relevant for SMBus. The default
1637 * probe method is a quick write, but it is known to corrupt the 24RF08
1638 * EEPROMs due to a state machine bug, and could also irreversibly
1639 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
1640 * we use a short byte read instead. Also, some bus drivers don't implement
1641 * quick write, so we fallback to a byte read in that case too.
1642 * On x86, there is another special case for FSC hardware monitoring chips,
1643 * which want regular byte reads (address 0x73.) Fortunately, these are the
1644 * only known chips using this I2C address on PC hardware.
1645 * Returns 1 if probe succeeded, 0 if not.
1647 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
1650 union i2c_smbus_data dummy;
1653 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
1654 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
1655 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1656 I2C_SMBUS_BYTE_DATA, &dummy);
1659 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
1660 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
1661 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
1662 I2C_SMBUS_QUICK, NULL);
1663 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
1664 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1665 I2C_SMBUS_BYTE, &dummy);
1667 dev_warn(&adap->dev, "No suitable probing method supported\n");
1674 static int i2c_detect_address(struct i2c_client *temp_client,
1675 struct i2c_driver *driver)
1677 struct i2c_board_info info;
1678 struct i2c_adapter *adapter = temp_client->adapter;
1679 int addr = temp_client->addr;
1682 /* Make sure the address is valid */
1683 err = i2c_check_addr_validity(addr);
1685 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
1690 /* Skip if already in use */
1691 if (i2c_check_addr_busy(adapter, addr))
1694 /* Make sure there is something at this address */
1695 if (!i2c_default_probe(adapter, addr))
1698 /* Finally call the custom detection function */
1699 memset(&info, 0, sizeof(struct i2c_board_info));
1701 err = driver->detect(temp_client, &info);
1703 /* -ENODEV is returned if the detection fails. We catch it
1704 here as this isn't an error. */
1705 return err == -ENODEV ? 0 : err;
1708 /* Consistency check */
1709 if (info.type[0] == '\0') {
1710 dev_err(&adapter->dev, "%s detection function provided "
1711 "no name for 0x%x\n", driver->driver.name,
1714 struct i2c_client *client;
1716 /* Detection succeeded, instantiate the device */
1717 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
1718 info.type, info.addr);
1719 client = i2c_new_device(adapter, &info);
1721 list_add_tail(&client->detected, &driver->clients);
1723 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
1724 info.type, info.addr);
1729 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
1731 const unsigned short *address_list;
1732 struct i2c_client *temp_client;
1734 int adap_id = i2c_adapter_id(adapter);
1736 address_list = driver->address_list;
1737 if (!driver->detect || !address_list)
1740 /* Stop here if the classes do not match */
1741 if (!(adapter->class & driver->class))
1744 /* Set up a temporary client to help detect callback */
1745 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
1748 temp_client->adapter = adapter;
1750 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
1751 dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
1752 "addr 0x%02x\n", adap_id, address_list[i]);
1753 temp_client->addr = address_list[i];
1754 err = i2c_detect_address(temp_client, driver);
1763 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
1765 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
1766 I2C_SMBUS_QUICK, NULL) >= 0;
1768 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
1771 i2c_new_probed_device(struct i2c_adapter *adap,
1772 struct i2c_board_info *info,
1773 unsigned short const *addr_list,
1774 int (*probe)(struct i2c_adapter *, unsigned short addr))
1779 probe = i2c_default_probe;
1781 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
1782 /* Check address validity */
1783 if (i2c_check_addr_validity(addr_list[i]) < 0) {
1784 dev_warn(&adap->dev, "Invalid 7-bit address "
1785 "0x%02x\n", addr_list[i]);
1789 /* Check address availability */
1790 if (i2c_check_addr_busy(adap, addr_list[i])) {
1791 dev_dbg(&adap->dev, "Address 0x%02x already in "
1792 "use, not probing\n", addr_list[i]);
1796 /* Test address responsiveness */
1797 if (probe(adap, addr_list[i]))
1801 if (addr_list[i] == I2C_CLIENT_END) {
1802 dev_dbg(&adap->dev, "Probing failed, no device found\n");
1806 info->addr = addr_list[i];
1807 return i2c_new_device(adap, info);
1809 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
1811 struct i2c_adapter *i2c_get_adapter(int nr)
1813 struct i2c_adapter *adapter;
1815 mutex_lock(&core_lock);
1816 adapter = idr_find(&i2c_adapter_idr, nr);
1817 if (adapter && !try_module_get(adapter->owner))
1820 mutex_unlock(&core_lock);
1823 EXPORT_SYMBOL(i2c_get_adapter);
1825 void i2c_put_adapter(struct i2c_adapter *adap)
1827 module_put(adap->owner);
1829 EXPORT_SYMBOL(i2c_put_adapter);
1831 /* The SMBus parts */
1833 #define POLY (0x1070U << 3)
1834 static u8 crc8(u16 data)
1838 for (i = 0; i < 8; i++) {
1843 return (u8)(data >> 8);
1846 /* Incremental CRC8 over count bytes in the array pointed to by p */
1847 static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
1851 for (i = 0; i < count; i++)
1852 crc = crc8((crc ^ p[i]) << 8);
1856 /* Assume a 7-bit address, which is reasonable for SMBus */
1857 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
1859 /* The address will be sent first */
1860 u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
1861 pec = i2c_smbus_pec(pec, &addr, 1);
1863 /* The data buffer follows */
1864 return i2c_smbus_pec(pec, msg->buf, msg->len);
1867 /* Used for write only transactions */
1868 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
1870 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
1874 /* Return <0 on CRC error
1875 If there was a write before this read (most cases) we need to take the
1876 partial CRC from the write part into account.
1877 Note that this function does modify the message (we need to decrease the
1878 message length to hide the CRC byte from the caller). */
1879 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
1881 u8 rpec = msg->buf[--msg->len];
1882 cpec = i2c_smbus_msg_pec(cpec, msg);
1885 pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
1893 * i2c_smbus_read_byte - SMBus "receive byte" protocol
1894 * @client: Handle to slave device
1896 * This executes the SMBus "receive byte" protocol, returning negative errno
1897 * else the byte received from the device.
1899 s32 i2c_smbus_read_byte(const struct i2c_client *client)
1901 union i2c_smbus_data data;
1904 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1906 I2C_SMBUS_BYTE, &data);
1907 return (status < 0) ? status : data.byte;
1909 EXPORT_SYMBOL(i2c_smbus_read_byte);
1912 * i2c_smbus_write_byte - SMBus "send byte" protocol
1913 * @client: Handle to slave device
1914 * @value: Byte to be sent
1916 * This executes the SMBus "send byte" protocol, returning negative errno
1917 * else zero on success.
1919 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
1921 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1922 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
1924 EXPORT_SYMBOL(i2c_smbus_write_byte);
1927 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
1928 * @client: Handle to slave device
1929 * @command: Byte interpreted by slave
1931 * This executes the SMBus "read byte" protocol, returning negative errno
1932 * else a data byte received from the device.
1934 s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
1936 union i2c_smbus_data data;
1939 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1940 I2C_SMBUS_READ, command,
1941 I2C_SMBUS_BYTE_DATA, &data);
1942 return (status < 0) ? status : data.byte;
1944 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
1947 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
1948 * @client: Handle to slave device
1949 * @command: Byte interpreted by slave
1950 * @value: Byte being written
1952 * This executes the SMBus "write byte" protocol, returning negative errno
1953 * else zero on success.
1955 s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
1958 union i2c_smbus_data data;
1960 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1961 I2C_SMBUS_WRITE, command,
1962 I2C_SMBUS_BYTE_DATA, &data);
1964 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
1967 * i2c_smbus_read_word_data - SMBus "read word" protocol
1968 * @client: Handle to slave device
1969 * @command: Byte interpreted by slave
1971 * This executes the SMBus "read word" protocol, returning negative errno
1972 * else a 16-bit unsigned "word" received from the device.
1974 s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
1976 union i2c_smbus_data data;
1979 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
1980 I2C_SMBUS_READ, command,
1981 I2C_SMBUS_WORD_DATA, &data);
1982 return (status < 0) ? status : data.word;
1984 EXPORT_SYMBOL(i2c_smbus_read_word_data);
1987 * i2c_smbus_write_word_data - SMBus "write word" protocol
1988 * @client: Handle to slave device
1989 * @command: Byte interpreted by slave
1990 * @value: 16-bit "word" being written
1992 * This executes the SMBus "write word" protocol, returning negative errno
1993 * else zero on success.
1995 s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
1998 union i2c_smbus_data data;
2000 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2001 I2C_SMBUS_WRITE, command,
2002 I2C_SMBUS_WORD_DATA, &data);
2004 EXPORT_SYMBOL(i2c_smbus_write_word_data);
2007 * i2c_smbus_read_block_data - SMBus "block read" protocol
2008 * @client: Handle to slave device
2009 * @command: Byte interpreted by slave
2010 * @values: Byte array into which data will be read; big enough to hold
2011 * the data returned by the slave. SMBus allows at most 32 bytes.
2013 * This executes the SMBus "block read" protocol, returning negative errno
2014 * else the number of data bytes in the slave's response.
2016 * Note that using this function requires that the client's adapter support
2017 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
2018 * support this; its emulation through I2C messaging relies on a specific
2019 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
2021 s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
2024 union i2c_smbus_data data;
2027 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2028 I2C_SMBUS_READ, command,
2029 I2C_SMBUS_BLOCK_DATA, &data);
2033 memcpy(values, &data.block[1], data.block[0]);
2034 return data.block[0];
2036 EXPORT_SYMBOL(i2c_smbus_read_block_data);
2039 * i2c_smbus_write_block_data - SMBus "block write" protocol
2040 * @client: Handle to slave device
2041 * @command: Byte interpreted by slave
2042 * @length: Size of data block; SMBus allows at most 32 bytes
2043 * @values: Byte array which will be written.
2045 * This executes the SMBus "block write" protocol, returning negative errno
2046 * else zero on success.
2048 s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
2049 u8 length, const u8 *values)
2051 union i2c_smbus_data data;
2053 if (length > I2C_SMBUS_BLOCK_MAX)
2054 length = I2C_SMBUS_BLOCK_MAX;
2055 data.block[0] = length;
2056 memcpy(&data.block[1], values, length);
2057 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2058 I2C_SMBUS_WRITE, command,
2059 I2C_SMBUS_BLOCK_DATA, &data);
2061 EXPORT_SYMBOL(i2c_smbus_write_block_data);
2063 /* Returns the number of read bytes */
2064 s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
2065 u8 length, u8 *values)
2067 union i2c_smbus_data data;
2070 if (length > I2C_SMBUS_BLOCK_MAX)
2071 length = I2C_SMBUS_BLOCK_MAX;
2072 data.block[0] = length;
2073 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2074 I2C_SMBUS_READ, command,
2075 I2C_SMBUS_I2C_BLOCK_DATA, &data);
2079 memcpy(values, &data.block[1], data.block[0]);
2080 return data.block[0];
2082 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
2084 s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
2085 u8 length, const u8 *values)
2087 union i2c_smbus_data data;
2089 if (length > I2C_SMBUS_BLOCK_MAX)
2090 length = I2C_SMBUS_BLOCK_MAX;
2091 data.block[0] = length;
2092 memcpy(data.block + 1, values, length);
2093 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
2094 I2C_SMBUS_WRITE, command,
2095 I2C_SMBUS_I2C_BLOCK_DATA, &data);
2097 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
2099 /* Simulate a SMBus command using the i2c protocol
2100 No checking of parameters is done! */
2101 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
2102 unsigned short flags,
2103 char read_write, u8 command, int size,
2104 union i2c_smbus_data *data)
2106 /* So we need to generate a series of msgs. In the case of writing, we
2107 need to use only one message; when reading, we need two. We initialize
2108 most things with sane defaults, to keep the code below somewhat
2110 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
2111 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
2112 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
2116 struct i2c_msg msg[2] = {
2124 .flags = flags | I2C_M_RD,
2130 msgbuf0[0] = command;
2132 case I2C_SMBUS_QUICK:
2134 /* Special case: The read/write field is used as data */
2135 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
2139 case I2C_SMBUS_BYTE:
2140 if (read_write == I2C_SMBUS_READ) {
2141 /* Special case: only a read! */
2142 msg[0].flags = I2C_M_RD | flags;
2146 case I2C_SMBUS_BYTE_DATA:
2147 if (read_write == I2C_SMBUS_READ)
2151 msgbuf0[1] = data->byte;
2154 case I2C_SMBUS_WORD_DATA:
2155 if (read_write == I2C_SMBUS_READ)
2159 msgbuf0[1] = data->word & 0xff;
2160 msgbuf0[2] = data->word >> 8;
2163 case I2C_SMBUS_PROC_CALL:
2164 num = 2; /* Special case */
2165 read_write = I2C_SMBUS_READ;
2168 msgbuf0[1] = data->word & 0xff;
2169 msgbuf0[2] = data->word >> 8;
2171 case I2C_SMBUS_BLOCK_DATA:
2172 if (read_write == I2C_SMBUS_READ) {
2173 msg[1].flags |= I2C_M_RECV_LEN;
2174 msg[1].len = 1; /* block length will be added by
2175 the underlying bus driver */
2177 msg[0].len = data->block[0] + 2;
2178 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
2179 dev_err(&adapter->dev,
2180 "Invalid block write size %d\n",
2184 for (i = 1; i < msg[0].len; i++)
2185 msgbuf0[i] = data->block[i-1];
2188 case I2C_SMBUS_BLOCK_PROC_CALL:
2189 num = 2; /* Another special case */
2190 read_write = I2C_SMBUS_READ;
2191 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
2192 dev_err(&adapter->dev,
2193 "Invalid block write size %d\n",
2197 msg[0].len = data->block[0] + 2;
2198 for (i = 1; i < msg[0].len; i++)
2199 msgbuf0[i] = data->block[i-1];
2200 msg[1].flags |= I2C_M_RECV_LEN;
2201 msg[1].len = 1; /* block length will be added by
2202 the underlying bus driver */
2204 case I2C_SMBUS_I2C_BLOCK_DATA:
2205 if (read_write == I2C_SMBUS_READ) {
2206 msg[1].len = data->block[0];
2208 msg[0].len = data->block[0] + 1;
2209 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
2210 dev_err(&adapter->dev,
2211 "Invalid block write size %d\n",
2215 for (i = 1; i <= data->block[0]; i++)
2216 msgbuf0[i] = data->block[i];
2220 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
2224 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
2225 && size != I2C_SMBUS_I2C_BLOCK_DATA);
2227 /* Compute PEC if first message is a write */
2228 if (!(msg[0].flags & I2C_M_RD)) {
2229 if (num == 1) /* Write only */
2230 i2c_smbus_add_pec(&msg[0]);
2231 else /* Write followed by read */
2232 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
2234 /* Ask for PEC if last message is a read */
2235 if (msg[num-1].flags & I2C_M_RD)
2239 status = i2c_transfer(adapter, msg, num);
2243 /* Check PEC if last message is a read */
2244 if (i && (msg[num-1].flags & I2C_M_RD)) {
2245 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
2250 if (read_write == I2C_SMBUS_READ)
2252 case I2C_SMBUS_BYTE:
2253 data->byte = msgbuf0[0];
2255 case I2C_SMBUS_BYTE_DATA:
2256 data->byte = msgbuf1[0];
2258 case I2C_SMBUS_WORD_DATA:
2259 case I2C_SMBUS_PROC_CALL:
2260 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
2262 case I2C_SMBUS_I2C_BLOCK_DATA:
2263 for (i = 0; i < data->block[0]; i++)
2264 data->block[i+1] = msgbuf1[i];
2266 case I2C_SMBUS_BLOCK_DATA:
2267 case I2C_SMBUS_BLOCK_PROC_CALL:
2268 for (i = 0; i < msgbuf1[0] + 1; i++)
2269 data->block[i] = msgbuf1[i];
2276 * i2c_smbus_xfer - execute SMBus protocol operations
2277 * @adapter: Handle to I2C bus
2278 * @addr: Address of SMBus slave on that bus
2279 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
2280 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
2281 * @command: Byte interpreted by slave, for protocols which use such bytes
2282 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
2283 * @data: Data to be read or written
2285 * This executes an SMBus protocol operation, and returns a negative
2286 * errno code else zero on success.
2288 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
2289 char read_write, u8 command, int protocol,
2290 union i2c_smbus_data *data)
2292 unsigned long orig_jiffies;
2296 flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB;
2298 if (adapter->algo->smbus_xfer) {
2299 i2c_lock_adapter(adapter);
2301 /* Retry automatically on arbitration loss */
2302 orig_jiffies = jiffies;
2303 for (res = 0, try = 0; try <= adapter->retries; try++) {
2304 res = adapter->algo->smbus_xfer(adapter, addr, flags,
2305 read_write, command,
2309 if (time_after(jiffies,
2310 orig_jiffies + adapter->timeout))
2313 i2c_unlock_adapter(adapter);
2315 if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)
2318 * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't
2319 * implement native support for the SMBus operation.
2323 return i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
2324 command, protocol, data);
2326 EXPORT_SYMBOL(i2c_smbus_xfer);
2328 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2329 MODULE_DESCRIPTION("I2C-Bus main module");
2330 MODULE_LICENSE("GPL");