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i2c-core.c
1867 lines (1621 loc) · 51.3 KB
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i2c-core.c
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/* i2c-core.c - a device driver for the iic-bus interface */
/* ------------------------------------------------------------------------- */
/* Copyright (C) 1995-99 Simon G. Vogl
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
/* ------------------------------------------------------------------------- */
/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
Jean Delvare <khali@linux-fr.org> */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/idr.h>
#include <linux/mutex.h>
#include <linux/completion.h>
#include <linux/hardirq.h>
#include <linux/irqflags.h>
#include <linux/rwsem.h>
#include <asm/uaccess.h>
#include "i2c-core.h"
/* core_lock protects i2c_adapter_idr, userspace_devices, and guarantees
that device detection, deletion of detected devices, and attach_adapter
and detach_adapter calls are serialized */
static DEFINE_MUTEX(core_lock);
static DEFINE_IDR(i2c_adapter_idr);
static LIST_HEAD(userspace_devices);
static int i2c_check_addr(struct i2c_adapter *adapter, int addr);
static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
/* ------------------------------------------------------------------------- */
static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
const struct i2c_client *client)
{
while (id->name[0]) {
if (strcmp(client->name, id->name) == 0)
return id;
id++;
}
return NULL;
}
static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
struct i2c_client *client = to_i2c_client(dev);
struct i2c_driver *driver = to_i2c_driver(drv);
/* match on an id table if there is one */
if (driver->id_table)
return i2c_match_id(driver->id_table, client) != NULL;
return 0;
}
#ifdef CONFIG_HOTPLUG
/* uevent helps with hotplug: modprobe -q $(MODALIAS) */
static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
{
struct i2c_client *client = to_i2c_client(dev);
if (add_uevent_var(env, "MODALIAS=%s%s",
I2C_MODULE_PREFIX, client->name))
return -ENOMEM;
dev_dbg(dev, "uevent\n");
return 0;
}
#else
#define i2c_device_uevent NULL
#endif /* CONFIG_HOTPLUG */
static int i2c_device_probe(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct i2c_driver *driver = to_i2c_driver(dev->driver);
int status;
if (!driver->probe || !driver->id_table)
return -ENODEV;
client->driver = driver;
if (!device_can_wakeup(&client->dev))
device_init_wakeup(&client->dev,
client->flags & I2C_CLIENT_WAKE);
dev_dbg(dev, "probe\n");
status = driver->probe(client, i2c_match_id(driver->id_table, client));
if (status)
client->driver = NULL;
return status;
}
static int i2c_device_remove(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct i2c_driver *driver;
int status;
if (!dev->driver)
return 0;
driver = to_i2c_driver(dev->driver);
if (driver->remove) {
dev_dbg(dev, "remove\n");
status = driver->remove(client);
} else {
dev->driver = NULL;
status = 0;
}
if (status == 0)
client->driver = NULL;
return status;
}
static void i2c_device_shutdown(struct device *dev)
{
struct i2c_driver *driver;
if (!dev->driver)
return;
driver = to_i2c_driver(dev->driver);
if (driver->shutdown)
driver->shutdown(to_i2c_client(dev));
}
static int i2c_device_suspend(struct device *dev, pm_message_t mesg)
{
struct i2c_driver *driver;
if (!dev->driver)
return 0;
driver = to_i2c_driver(dev->driver);
if (!driver->suspend)
return 0;
return driver->suspend(to_i2c_client(dev), mesg);
}
static int i2c_device_resume(struct device *dev)
{
struct i2c_driver *driver;
if (!dev->driver)
return 0;
driver = to_i2c_driver(dev->driver);
if (!driver->resume)
return 0;
return driver->resume(to_i2c_client(dev));
}
static void i2c_client_dev_release(struct device *dev)
{
kfree(to_i2c_client(dev));
}
static ssize_t
show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
return sprintf(buf, "%s\n", client->name);
}
static ssize_t
show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
}
static struct device_attribute i2c_dev_attrs[] = {
__ATTR(name, S_IRUGO, show_client_name, NULL),
/* modalias helps coldplug: modprobe $(cat .../modalias) */
__ATTR(modalias, S_IRUGO, show_modalias, NULL),
{ },
};
struct bus_type i2c_bus_type = {
.name = "i2c",
.dev_attrs = i2c_dev_attrs,
.match = i2c_device_match,
.uevent = i2c_device_uevent,
.probe = i2c_device_probe,
.remove = i2c_device_remove,
.shutdown = i2c_device_shutdown,
.suspend = i2c_device_suspend,
.resume = i2c_device_resume,
};
EXPORT_SYMBOL_GPL(i2c_bus_type);
/**
* i2c_verify_client - return parameter as i2c_client, or NULL
* @dev: device, probably from some driver model iterator
*
* When traversing the driver model tree, perhaps using driver model
* iterators like @device_for_each_child(), you can't assume very much
* about the nodes you find. Use this function to avoid oopses caused
* by wrongly treating some non-I2C device as an i2c_client.
*/
struct i2c_client *i2c_verify_client(struct device *dev)
{
return (dev->bus == &i2c_bus_type)
? to_i2c_client(dev)
: NULL;
}
EXPORT_SYMBOL(i2c_verify_client);
/**
* i2c_new_device - instantiate an i2c device
* @adap: the adapter managing the device
* @info: describes one I2C device; bus_num is ignored
* Context: can sleep
*
* Create an i2c device. Binding is handled through driver model
* probe()/remove() methods. A driver may be bound to this device when we
* return from this function, or any later moment (e.g. maybe hotplugging will
* load the driver module). This call is not appropriate for use by mainboard
* initialization logic, which usually runs during an arch_initcall() long
* before any i2c_adapter could exist.
*
* This returns the new i2c client, which may be saved for later use with
* i2c_unregister_device(); or NULL to indicate an error.
*/
struct i2c_client *
i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
{
struct i2c_client *client;
int status;
client = kzalloc(sizeof *client, GFP_KERNEL);
if (!client)
return NULL;
client->adapter = adap;
client->dev.platform_data = info->platform_data;
if (info->archdata)
client->dev.archdata = *info->archdata;
client->flags = info->flags;
client->addr = info->addr;
client->irq = info->irq;
strlcpy(client->name, info->type, sizeof(client->name));
/* Check for address business */
status = i2c_check_addr(adap, client->addr);
if (status)
goto out_err;
client->dev.parent = &client->adapter->dev;
client->dev.bus = &i2c_bus_type;
client->dev.release = i2c_client_dev_release;
dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
client->addr);
status = device_register(&client->dev);
if (status)
goto out_err;
dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
client->name, dev_name(&client->dev));
return client;
out_err:
dev_err(&adap->dev, "Failed to register i2c client %s at 0x%02x "
"(%d)\n", client->name, client->addr, status);
kfree(client);
return NULL;
}
EXPORT_SYMBOL_GPL(i2c_new_device);
/**
* i2c_unregister_device - reverse effect of i2c_new_device()
* @client: value returned from i2c_new_device()
* Context: can sleep
*/
void i2c_unregister_device(struct i2c_client *client)
{
device_unregister(&client->dev);
}
EXPORT_SYMBOL_GPL(i2c_unregister_device);
static const struct i2c_device_id dummy_id[] = {
{ "dummy", 0 },
{ },
};
static int dummy_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
return 0;
}
static int dummy_remove(struct i2c_client *client)
{
return 0;
}
static struct i2c_driver dummy_driver = {
.driver.name = "dummy",
.probe = dummy_probe,
.remove = dummy_remove,
.id_table = dummy_id,
};
/**
* i2c_new_dummy - return a new i2c device bound to a dummy driver
* @adapter: the adapter managing the device
* @address: seven bit address to be used
* Context: can sleep
*
* This returns an I2C client bound to the "dummy" driver, intended for use
* with devices that consume multiple addresses. Examples of such chips
* include various EEPROMS (like 24c04 and 24c08 models).
*
* These dummy devices have two main uses. First, most I2C and SMBus calls
* except i2c_transfer() need a client handle; the dummy will be that handle.
* And second, this prevents the specified address from being bound to a
* different driver.
*
* This returns the new i2c client, which should be saved for later use with
* i2c_unregister_device(); or NULL to indicate an error.
*/
struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
{
struct i2c_board_info info = {
I2C_BOARD_INFO("dummy", address),
};
return i2c_new_device(adapter, &info);
}
EXPORT_SYMBOL_GPL(i2c_new_dummy);
/* ------------------------------------------------------------------------- */
/* I2C bus adapters -- one roots each I2C or SMBUS segment */
static void i2c_adapter_dev_release(struct device *dev)
{
struct i2c_adapter *adap = to_i2c_adapter(dev);
complete(&adap->dev_released);
}
static ssize_t
show_adapter_name(struct device *dev, struct device_attribute *attr, char *buf)
{
struct i2c_adapter *adap = to_i2c_adapter(dev);
return sprintf(buf, "%s\n", adap->name);
}
/*
* Let users instantiate I2C devices through sysfs. This can be used when
* platform initialization code doesn't contain the proper data for
* whatever reason. Also useful for drivers that do device detection and
* detection fails, either because the device uses an unexpected address,
* or this is a compatible device with different ID register values.
*
* Parameter checking may look overzealous, but we really don't want
* the user to provide incorrect parameters.
*/
static ssize_t
i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct i2c_adapter *adap = to_i2c_adapter(dev);
struct i2c_board_info info;
struct i2c_client *client;
char *blank, end;
int res;
dev_warn(dev, "The new_device interface is still experimental "
"and may change in a near future\n");
memset(&info, 0, sizeof(struct i2c_board_info));
blank = strchr(buf, ' ');
if (!blank) {
dev_err(dev, "%s: Missing parameters\n", "new_device");
return -EINVAL;
}
if (blank - buf > I2C_NAME_SIZE - 1) {
dev_err(dev, "%s: Invalid device name\n", "new_device");
return -EINVAL;
}
memcpy(info.type, buf, blank - buf);
/* Parse remaining parameters, reject extra parameters */
res = sscanf(++blank, "%hi%c", &info.addr, &end);
if (res < 1) {
dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
return -EINVAL;
}
if (res > 1 && end != '\n') {
dev_err(dev, "%s: Extra parameters\n", "new_device");
return -EINVAL;
}
if (info.addr < 0x03 || info.addr > 0x77) {
dev_err(dev, "%s: Invalid I2C address 0x%hx\n", "new_device",
info.addr);
return -EINVAL;
}
client = i2c_new_device(adap, &info);
if (!client)
return -EEXIST;
/* Keep track of the added device */
mutex_lock(&core_lock);
list_add_tail(&client->detected, &userspace_devices);
mutex_unlock(&core_lock);
dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
info.type, info.addr);
return count;
}
/*
* And of course let the users delete the devices they instantiated, if
* they got it wrong. This interface can only be used to delete devices
* instantiated by i2c_sysfs_new_device above. This guarantees that we
* don't delete devices to which some kernel code still has references.
*
* Parameter checking may look overzealous, but we really don't want
* the user to delete the wrong device.
*/
static ssize_t
i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct i2c_adapter *adap = to_i2c_adapter(dev);
struct i2c_client *client, *next;
unsigned short addr;
char end;
int res;
/* Parse parameters, reject extra parameters */
res = sscanf(buf, "%hi%c", &addr, &end);
if (res < 1) {
dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
return -EINVAL;
}
if (res > 1 && end != '\n') {
dev_err(dev, "%s: Extra parameters\n", "delete_device");
return -EINVAL;
}
/* Make sure the device was added through sysfs */
res = -ENOENT;
mutex_lock(&core_lock);
list_for_each_entry_safe(client, next, &userspace_devices, detected) {
if (client->addr == addr && client->adapter == adap) {
dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
"delete_device", client->name, client->addr);
list_del(&client->detected);
i2c_unregister_device(client);
res = count;
break;
}
}
mutex_unlock(&core_lock);
if (res < 0)
dev_err(dev, "%s: Can't find device in list\n",
"delete_device");
return res;
}
static struct device_attribute i2c_adapter_attrs[] = {
__ATTR(name, S_IRUGO, show_adapter_name, NULL),
__ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device),
__ATTR(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device),
{ },
};
static struct class i2c_adapter_class = {
.owner = THIS_MODULE,
.name = "i2c-adapter",
.dev_attrs = i2c_adapter_attrs,
};
static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
{
struct i2c_devinfo *devinfo;
down_read(&__i2c_board_lock);
list_for_each_entry(devinfo, &__i2c_board_list, list) {
if (devinfo->busnum == adapter->nr
&& !i2c_new_device(adapter,
&devinfo->board_info))
dev_err(&adapter->dev,
"Can't create device at 0x%02x\n",
devinfo->board_info.addr);
}
up_read(&__i2c_board_lock);
}
static int i2c_do_add_adapter(struct device_driver *d, void *data)
{
struct i2c_driver *driver = to_i2c_driver(d);
struct i2c_adapter *adap = data;
/* Detect supported devices on that bus, and instantiate them */
i2c_detect(adap, driver);
/* Let legacy drivers scan this bus for matching devices */
if (driver->attach_adapter) {
/* We ignore the return code; if it fails, too bad */
driver->attach_adapter(adap);
}
return 0;
}
static int i2c_register_adapter(struct i2c_adapter *adap)
{
int res = 0, dummy;
/* Can't register until after driver model init */
if (unlikely(WARN_ON(!i2c_bus_type.p))) {
res = -EAGAIN;
goto out_list;
}
mutex_init(&adap->bus_lock);
/* Set default timeout to 1 second if not already set */
if (adap->timeout == 0)
adap->timeout = HZ;
dev_set_name(&adap->dev, "i2c-%d", adap->nr);
adap->dev.release = &i2c_adapter_dev_release;
adap->dev.class = &i2c_adapter_class;
res = device_register(&adap->dev);
if (res)
goto out_list;
dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
/* create pre-declared device nodes */
if (adap->nr < __i2c_first_dynamic_bus_num)
i2c_scan_static_board_info(adap);
/* Notify drivers */
mutex_lock(&core_lock);
dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,
i2c_do_add_adapter);
mutex_unlock(&core_lock);
return 0;
out_list:
mutex_lock(&core_lock);
idr_remove(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
return res;
}
/**
* i2c_add_adapter - declare i2c adapter, use dynamic bus number
* @adapter: the adapter to add
* Context: can sleep
*
* This routine is used to declare an I2C adapter when its bus number
* doesn't matter. Examples: for I2C adapters dynamically added by
* USB links or PCI plugin cards.
*
* When this returns zero, a new bus number was allocated and stored
* in adap->nr, and the specified adapter became available for clients.
* Otherwise, a negative errno value is returned.
*/
int i2c_add_adapter(struct i2c_adapter *adapter)
{
int id, res = 0;
retry:
if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
return -ENOMEM;
mutex_lock(&core_lock);
/* "above" here means "above or equal to", sigh */
res = idr_get_new_above(&i2c_adapter_idr, adapter,
__i2c_first_dynamic_bus_num, &id);
mutex_unlock(&core_lock);
if (res < 0) {
if (res == -EAGAIN)
goto retry;
return res;
}
adapter->nr = id;
return i2c_register_adapter(adapter);
}
EXPORT_SYMBOL(i2c_add_adapter);
/**
* i2c_add_numbered_adapter - declare i2c adapter, use static bus number
* @adap: the adapter to register (with adap->nr initialized)
* Context: can sleep
*
* This routine is used to declare an I2C adapter when its bus number
* matters. For example, use it for I2C adapters from system-on-chip CPUs,
* or otherwise built in to the system's mainboard, and where i2c_board_info
* is used to properly configure I2C devices.
*
* If no devices have pre-been declared for this bus, then be sure to
* register the adapter before any dynamically allocated ones. Otherwise
* the required bus ID may not be available.
*
* When this returns zero, the specified adapter became available for
* clients using the bus number provided in adap->nr. Also, the table
* of I2C devices pre-declared using i2c_register_board_info() is scanned,
* and the appropriate driver model device nodes are created. Otherwise, a
* negative errno value is returned.
*/
int i2c_add_numbered_adapter(struct i2c_adapter *adap)
{
int id;
int status;
if (adap->nr & ~MAX_ID_MASK)
return -EINVAL;
retry:
if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
return -ENOMEM;
mutex_lock(&core_lock);
/* "above" here means "above or equal to", sigh;
* we need the "equal to" result to force the result
*/
status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
if (status == 0 && id != adap->nr) {
status = -EBUSY;
idr_remove(&i2c_adapter_idr, id);
}
mutex_unlock(&core_lock);
if (status == -EAGAIN)
goto retry;
if (status == 0)
status = i2c_register_adapter(adap);
return status;
}
EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
static int i2c_do_del_adapter(struct device_driver *d, void *data)
{
struct i2c_driver *driver = to_i2c_driver(d);
struct i2c_adapter *adapter = data;
struct i2c_client *client, *_n;
int res;
/* Remove the devices we created ourselves as the result of hardware
* probing (using a driver's detect method) */
list_for_each_entry_safe(client, _n, &driver->clients, detected) {
if (client->adapter == adapter) {
dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
client->name, client->addr);
list_del(&client->detected);
i2c_unregister_device(client);
}
}
if (!driver->detach_adapter)
return 0;
res = driver->detach_adapter(adapter);
if (res)
dev_err(&adapter->dev, "detach_adapter failed (%d) "
"for driver [%s]\n", res, driver->driver.name);
return res;
}
static int __unregister_client(struct device *dev, void *dummy)
{
struct i2c_client *client = i2c_verify_client(dev);
if (client)
i2c_unregister_device(client);
return 0;
}
/**
* i2c_del_adapter - unregister I2C adapter
* @adap: the adapter being unregistered
* Context: can sleep
*
* This unregisters an I2C adapter which was previously registered
* by @i2c_add_adapter or @i2c_add_numbered_adapter.
*/
int i2c_del_adapter(struct i2c_adapter *adap)
{
int res = 0;
struct i2c_adapter *found;
/* First make sure that this adapter was ever added */
mutex_lock(&core_lock);
found = idr_find(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
if (found != adap) {
pr_debug("i2c-core: attempting to delete unregistered "
"adapter [%s]\n", adap->name);
return -EINVAL;
}
/* Tell drivers about this removal */
mutex_lock(&core_lock);
res = bus_for_each_drv(&i2c_bus_type, NULL, adap,
i2c_do_del_adapter);
mutex_unlock(&core_lock);
if (res)
return res;
/* Detach any active clients. This can't fail, thus we do not
checking the returned value. */
res = device_for_each_child(&adap->dev, NULL, __unregister_client);
/* clean up the sysfs representation */
init_completion(&adap->dev_released);
device_unregister(&adap->dev);
/* wait for sysfs to drop all references */
wait_for_completion(&adap->dev_released);
/* free bus id */
mutex_lock(&core_lock);
idr_remove(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
/* Clear the device structure in case this adapter is ever going to be
added again */
memset(&adap->dev, 0, sizeof(adap->dev));
return 0;
}
EXPORT_SYMBOL(i2c_del_adapter);
/* ------------------------------------------------------------------------- */
static int __attach_adapter(struct device *dev, void *data)
{
struct i2c_adapter *adapter = to_i2c_adapter(dev);
struct i2c_driver *driver = data;
i2c_detect(adapter, driver);
/* Legacy drivers scan i2c busses directly */
if (driver->attach_adapter)
driver->attach_adapter(adapter);
return 0;
}
/*
* An i2c_driver is used with one or more i2c_client (device) nodes to access
* i2c slave chips, on a bus instance associated with some i2c_adapter.
*/
int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
{
int res;
/* Can't register until after driver model init */
if (unlikely(WARN_ON(!i2c_bus_type.p)))
return -EAGAIN;
/* add the driver to the list of i2c drivers in the driver core */
driver->driver.owner = owner;
driver->driver.bus = &i2c_bus_type;
/* When registration returns, the driver core
* will have called probe() for all matching-but-unbound devices.
*/
res = driver_register(&driver->driver);
if (res)
return res;
pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
INIT_LIST_HEAD(&driver->clients);
/* Walk the adapters that are already present */
mutex_lock(&core_lock);
class_for_each_device(&i2c_adapter_class, NULL, driver,
__attach_adapter);
mutex_unlock(&core_lock);
return 0;
}
EXPORT_SYMBOL(i2c_register_driver);
static int __detach_adapter(struct device *dev, void *data)
{
struct i2c_adapter *adapter = to_i2c_adapter(dev);
struct i2c_driver *driver = data;
struct i2c_client *client, *_n;
/* Remove the devices we created ourselves as the result of hardware
* probing (using a driver's detect method) */
list_for_each_entry_safe(client, _n, &driver->clients, detected) {
dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
client->name, client->addr);
list_del(&client->detected);
i2c_unregister_device(client);
}
if (driver->detach_adapter) {
if (driver->detach_adapter(adapter))
dev_err(&adapter->dev,
"detach_adapter failed for driver [%s]\n",
driver->driver.name);
}
return 0;
}
/**
* i2c_del_driver - unregister I2C driver
* @driver: the driver being unregistered
* Context: can sleep
*/
void i2c_del_driver(struct i2c_driver *driver)
{
mutex_lock(&core_lock);
class_for_each_device(&i2c_adapter_class, NULL, driver,
__detach_adapter);
mutex_unlock(&core_lock);
driver_unregister(&driver->driver);
pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
}
EXPORT_SYMBOL(i2c_del_driver);
/* ------------------------------------------------------------------------- */
static int __i2c_check_addr(struct device *dev, void *addrp)
{
struct i2c_client *client = i2c_verify_client(dev);
int addr = *(int *)addrp;
if (client && client->addr == addr)
return -EBUSY;
return 0;
}
static int i2c_check_addr(struct i2c_adapter *adapter, int addr)
{
return device_for_each_child(&adapter->dev, &addr, __i2c_check_addr);
}
/**
* i2c_use_client - increments the reference count of the i2c client structure
* @client: the client being referenced
*
* Each live reference to a client should be refcounted. The driver model does
* that automatically as part of driver binding, so that most drivers don't
* need to do this explicitly: they hold a reference until they're unbound
* from the device.
*
* A pointer to the client with the incremented reference counter is returned.
*/
struct i2c_client *i2c_use_client(struct i2c_client *client)
{
if (client && get_device(&client->dev))
return client;
return NULL;
}
EXPORT_SYMBOL(i2c_use_client);
/**
* i2c_release_client - release a use of the i2c client structure
* @client: the client being no longer referenced
*
* Must be called when a user of a client is finished with it.
*/
void i2c_release_client(struct i2c_client *client)
{
if (client)
put_device(&client->dev);
}
EXPORT_SYMBOL(i2c_release_client);
struct i2c_cmd_arg {
unsigned cmd;
void *arg;
};
static int i2c_cmd(struct device *dev, void *_arg)
{
struct i2c_client *client = i2c_verify_client(dev);
struct i2c_cmd_arg *arg = _arg;
if (client && client->driver && client->driver->command)
client->driver->command(client, arg->cmd, arg->arg);
return 0;
}
void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
{
struct i2c_cmd_arg cmd_arg;
cmd_arg.cmd = cmd;
cmd_arg.arg = arg;
device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
}
EXPORT_SYMBOL(i2c_clients_command);
static int __init i2c_init(void)
{
int retval;
retval = bus_register(&i2c_bus_type);
if (retval)
return retval;
retval = class_register(&i2c_adapter_class);
if (retval)
goto bus_err;
retval = i2c_add_driver(&dummy_driver);
if (retval)
goto class_err;
return 0;
class_err:
class_unregister(&i2c_adapter_class);
bus_err:
bus_unregister(&i2c_bus_type);
return retval;
}
static void __exit i2c_exit(void)
{
i2c_del_driver(&dummy_driver);
class_unregister(&i2c_adapter_class);
bus_unregister(&i2c_bus_type);
}
/* We must initialize early, because some subsystems register i2c drivers
* in subsys_initcall() code, but are linked (and initialized) before i2c.
*/
postcore_initcall(i2c_init);
module_exit(i2c_exit);
/* ----------------------------------------------------
* the functional interface to the i2c busses.
* ----------------------------------------------------
*/
/**
* i2c_transfer - execute a single or combined I2C message
* @adap: Handle to I2C bus
* @msgs: One or more messages to execute before STOP is issued to
* terminate the operation; each message begins with a START.
* @num: Number of messages to be executed.
*
* Returns negative errno, else the number of messages executed.
*
* Note that there is no requirement that each message be sent to
* the same slave address, although that is the most common model.
*/
int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
unsigned long orig_jiffies;
int ret, try;
/* REVISIT the fault reporting model here is weak:
*
* - When we get an error after receiving N bytes from a slave,
* there is no way to report "N".
*
* - When we get a NAK after transmitting N bytes to a slave,
* there is no way to report "N" ... or to let the master
* continue executing the rest of this combined message, if