i2c-core.c

linux 内核源代码

/* 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 <[e-mail]>.
   All SMBus-related things are written by Frodo Looijaard <[e-mail]>
   SMBus 2.0 support by Mark Studebaker <[e-mail]> and
   Jean Delvare <[e-mail]> */

#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/seq_file.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/completion.h>
#include <asm/uaccess.h>

#include "i2c-core.h"


static LIST_HEAD(adapters);
static LIST_HEAD(drivers);
static DEFINE_MUTEX(core_lists);
static DEFINE_IDR(i2c_adapter_idr);

#define is_newstyle_driver(d) ((d)->probe || (d)->remove)

/* ------------------------------------------------------------------------- */

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);

	/* make legacy i2c drivers bypass driver model probing entirely;
	 * such drivers scan each i2c adapter/bus themselves.
	 */
	if (!is_newstyle_driver(driver))
		return 0;

	/* new style drivers use the same kind of driver matching policy
	 * as platform devices or SPI:  compare device and driver IDs.
	 */
	return strcmp(client->driver_name, drv->name) == 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);

	/* by definition, legacy drivers can't hotplug */
	if (dev->driver || !client->driver_name)
		return 0;

	if (add_uevent_var(env, "MODALIAS=%s", client->driver_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);

	if (!driver->probe)
		return -ENODEV;
	client->driver = driver;
	dev_dbg(dev, "probe\n");
	return driver->probe(client);
}

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_release(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	complete(&client->released);
}

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 client->driver_name
		? sprintf(buf, "%s\n", client->driver_name)
		: 0;
}

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),
	{ },
};

static 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,
};

/**
 * i2c_new_device - instantiate an i2c device for use with a new style driver
 * @adap: the adapter managing the device
 * @info: describes one I2C device; bus_num is ignored
 * Context: can sleep
 *
 * Create a device to work with a new style i2c driver, where binding is
 * handled through driver model probe()/remove() methods.  This call is not
 * appropriate for use by mainboad 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;
	device_init_wakeup(&client->dev, info->flags & I2C_CLIENT_WAKE);

	client->flags = info->flags & ~I2C_CLIENT_WAKE;
	client->addr = info->addr;
	client->irq = info->irq;

	strlcpy(client->driver_name, info->driver_name,
		sizeof(client->driver_name));
	strlcpy(client->name, info->type, sizeof(client->name));

	/* a new style 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).  and the device
	 * refcount model is the standard driver model one.
	 */
	status = i2c_attach_client(client);
	if (status < 0) {
		kfree(client);
		client = NULL;
	}
	return client;
}
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)
{
	struct i2c_adapter	*adapter = client->adapter;
	struct i2c_driver	*driver = client->driver;

	if (driver && !is_newstyle_driver(driver)) {
		dev_err(&client->dev, "can't unregister devices "
			"with legacy drivers\n");
		WARN_ON(1);
		return;
	}

	mutex_lock(&adapter->clist_lock);
	list_del(&client->list);
	mutex_unlock(&adapter->clist_lock);

	device_unregister(&client->dev);
}
EXPORT_SYMBOL_GPL(i2c_unregister_device);


/* ------------------------------------------------------------------------- */

/* 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);
}

static struct device_attribute i2c_adapter_attrs[] = {
	__ATTR(name, S_IRUGO, show_adapter_name, NULL),
	{ },
};

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;

	mutex_lock(&__i2c_board_lock);
	list_for_each_entry(devinfo, &__i2c_board_list, list) {
		if (devinfo->busnum == adapter->nr
				&& !i2c_new_device(adapter,
						&devinfo->board_info))
			printk(KERN_ERR "i2c-core: can't create i2c%d-%04x\n",
				i2c_adapter_id(adapter),
				devinfo->board_info.addr);
	}
	mutex_unlock(&__i2c_board_lock);
}

static int i2c_register_adapter(struct i2c_adapter *adap)
{
	int res = 0;
	struct list_head   *item;
	struct i2c_driver  *driver;

	mutex_init(&adap->bus_lock);
	mutex_init(&adap->clist_lock);
	INIT_LIST_HEAD(&adap->clients);

	mutex_lock(&core_lists);
	list_add_tail(&adap->list, &adapters);

	/* Add the adapter to the driver core.
	 * If the parent pointer is not set up,
	 * we add this adapter to the host bus.
	 */
	if (adap->dev.parent == NULL) {
		adap->dev.parent = &platform_bus;
		pr_debug("I2C adapter driver [%s] forgot to specify "
			 "physical device\n", adap->name);
	}
	sprintf(adap->dev.bus_id, "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 for new-style drivers */
	if (adap->nr < __i2c_first_dynamic_bus_num)
		i2c_scan_static_board_info(adap);

	/* let legacy drivers scan this bus for matching devices */
	list_for_each(item,&drivers) {
		driver = list_entry(item, struct i2c_driver, list);
		if (driver->attach_adapter)
			/* We ignore the return code; if it fails, too bad */
			driver->attach_adapter(adap);
	}

out_unlock:
	mutex_unlock(&core_lists);
	return res;

out_list:
	list_del(&adap->list);
	idr_remove(&i2c_adapter_idr, adap->nr);
	goto out_unlock;
}

/**
 * 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_lists);
	/* "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_lists);

	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.  Example: 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_lists);
	/* "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_lists);
	if (status == -EAGAIN)
		goto retry;

	if (status == 0)
		status = i2c_register_adapter(adap);
	return status;
}
EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);

/**
 * 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)
{
	struct list_head  *item, *_n;
	struct i2c_adapter *adap_from_list;
	struct i2c_driver *driver;
	struct i2c_client *client;
	int res = 0;

	mutex_lock(&core_lists);

	/* First make sure that this adapter was ever added */
	list_for_each_entry(adap_from_list, &adapters, list) {
		if (adap_from_list == adap)
			break;
	}
	if (adap_from_list != adap) {
		pr_debug("i2c-core: attempting to delete unregistered "
			 "adapter [%s]\n", adap->name);
		res = -EINVAL;
		goto out_unlock;
	}

	list_for_each(item,&drivers) {
		driver = list_entry(item, struct i2c_driver, list);
		if (driver->detach_adapter)
			if ((res = driver->detach_adapter(adap))) {
				dev_err(&adap->dev, "detach_adapter failed "
					"for driver [%s]\n",
					driver->driver.name);
				goto out_unlock;
			}
	}

	/* detach any active clients. This must be done first, because
	 * it can fail; in which case we give up. */
	list_for_each_safe(item, _n, &adap->clients) {
		struct i2c_driver	*driver;

		client = list_entry(item, struct i2c_client, list);
		driver = client->driver;

		/* new style, follow standard driver model */
		if (!driver || is_newstyle_driver(driver)) {
			i2c_unregister_device(client);
			continue;
		}