i2c-core.c

《linux驱动程序设计从入门到精通》一书中所有的程序代码含驱动和相应的应用程序

/* 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 Ky鰏ti M鋖kki <[e-mail]>.
   All SMBus-related things are written by Frodo Looijaard <[e-mail]>
   SMBus 2.0 support by Mark Studebaker <[e-mail]>                */

#include <linux/config.h>
#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 <asm/uaccess.h>


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

int i2c_device_probe(struct device *dev)
{
	return -ENODEV;
}

int i2c_device_remove(struct device *dev)
{
	return 0;
}

static void i2c_adapter_dev_release(struct device *dev)
{
	struct i2c_adapter *adap = dev_to_i2c_adapter(dev);
	complete(&adap->dev_released);
}

static struct device_driver i2c_adapter_driver = {
	.name =	"i2c_adapter",
	.bus = &i2c_bus_type,
	.probe = i2c_device_probe,
	.remove = i2c_device_remove,
};

static void i2c_adapter_class_dev_release(struct class_device *dev)
{
	struct i2c_adapter *adap = class_dev_to_i2c_adapter(dev);
	complete(&adap->class_dev_released);
}

static struct class i2c_adapter_class = {
	.name =		"i2c-adapter",
	.release =	&i2c_adapter_class_dev_release,
};

static ssize_t show_adapter_name(struct device *dev, char *buf)
{
	struct i2c_adapter *adap = dev_to_i2c_adapter(dev);
	return sprintf(buf, "%s\n", adap->name);
}
static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);


static void i2c_client_release(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	complete(&client->released);
}

static ssize_t show_client_name(struct device *dev, char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	return sprintf(buf, "%s\n", client->name);
}

/* 
 * We can't use the DEVICE_ATTR() macro here as we want the same filename for a
 * different type of a device.  So beware if the DEVICE_ATTR() macro ever
 * changes, this definition will also have to change.
 */
static struct device_attribute dev_attr_client_name = {
	.attr	= {.name = "name", .mode = S_IRUGO, .owner = THIS_MODULE },
	.show	= &show_client_name,
};


/* ---------------------------------------------------
 * registering functions 
 * --------------------------------------------------- 
 */

/* -----
 * i2c_add_adapter is called from within the algorithm layer,
 * when a new hw adapter registers. A new device is register to be
 * available for clients.
 */
int i2c_add_adapter(struct i2c_adapter *adap)
{
	int id, res = 0;
	struct list_head   *item;
	struct i2c_driver  *driver;

	down(&core_lists);

	if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0) {
		res = -ENOMEM;
		goto out_unlock;
	}

	res = idr_get_new(&i2c_adapter_idr, NULL, &id);
	if (res < 0) {
		if (res == -EAGAIN)
			res = -ENOMEM;
		goto out_unlock;
	}

	adap->nr =  id & MAX_ID_MASK;
	init_MUTEX(&adap->bus_lock);
	init_MUTEX(&adap->clist_lock);
	list_add_tail(&adap->list,&adapters);
	INIT_LIST_HEAD(&adap->clients);

	/* 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;
	sprintf(adap->dev.bus_id, "i2c-%d", adap->nr);
	adap->dev.driver = &i2c_adapter_driver;
	adap->dev.release = &i2c_adapter_dev_release;
	device_register(&adap->dev);
	device_create_file(&adap->dev, &dev_attr_name);

	/* Add this adapter to the i2c_adapter class */
	memset(&adap->class_dev, 0x00, sizeof(struct class_device));
	adap->class_dev.dev = &adap->dev;
	adap->class_dev.class = &i2c_adapter_class;
	strlcpy(adap->class_dev.class_id, adap->dev.bus_id, BUS_ID_SIZE);
	class_device_register(&adap->class_dev);

	/* inform drivers of new adapters */
	list_for_each(item,&drivers) {
		driver = list_entry(item, struct i2c_driver, list);
		if (driver->flags & I2C_DF_NOTIFY)
			/* We ignore the return code; if it fails, too bad */
			driver->attach_adapter(adap);
	}

	dev_dbg(&adap->dev, "registered as adapter #%d\n", adap->nr);

out_unlock:
	up(&core_lists);
	return res;
}


int i2c_del_adapter(struct i2c_adapter *adap)
{
	struct list_head  *item, *_n;
	struct i2c_driver *driver;
	struct i2c_client *client;
	int res = 0;

	down(&core_lists);

	list_for_each(item,&drivers) {
		driver = list_entry(item, struct i2c_driver, list);
		if (driver->detach_adapter)
			if ((res = driver->detach_adapter(adap))) {
				dev_warn(&adap->dev, "can't detach adapter "
					 "while detaching driver %s: driver not "
					 "detached!", driver->name);
				goto out_unlock;
			}
	}

	/* detach any active clients. This must be done first, because
	 * it can fail; in which case we give upp. */
	list_for_each_safe(item, _n, &adap->clients) {
		client = list_entry(item, struct i2c_client, list);

		/* detaching devices is unconditional of the set notify
		 * flag, as _all_ clients that reside on the adapter
		 * must be deleted, as this would cause invalid states.
		 */
		if ((res=client->driver->detach_client(client))) {
			dev_err(&adap->dev, "adapter not "
				"unregistered, because client at "
				"address %02x can't be detached. ",
				client->addr);
			goto out_unlock;
		}
	}

	/* clean up the sysfs representation */
	init_completion(&adap->dev_released);
	init_completion(&adap->class_dev_released);
	class_device_unregister(&adap->class_dev);
	device_remove_file(&adap->dev, &dev_attr_name);
	device_unregister(&adap->dev);
	list_del(&adap->list);

	/* wait for sysfs to drop all references */
	wait_for_completion(&adap->dev_released);
	wait_for_completion(&adap->class_dev_released);

	/* free dynamically allocated bus id */
	idr_remove(&i2c_adapter_idr, adap->nr);

	dev_dbg(&adap->dev, "adapter unregistered\n");

 out_unlock:
	up(&core_lists);
	return res;
}


/* -----
 * What follows is the "upwards" interface: commands for talking to clients,
 * which implement the functions to access the physical information of the
 * chips.
 */

int i2c_add_driver(struct i2c_driver *driver)
{
	struct list_head   *item;
	struct i2c_adapter *adapter;
	int res = 0;

	down(&core_lists);

	/* add the driver to the list of i2c drivers in the driver core */
	driver->driver.name = driver->name;
	driver->driver.bus = &i2c_bus_type;
	driver->driver.probe = i2c_device_probe;
	driver->driver.remove = i2c_device_remove;

	res = driver_register(&driver->driver);
	if (res)
		goto out_unlock;
	
	list_add_tail(&driver->list,&drivers);
	pr_debug("i2c-core: driver %s registered.\n", driver->name);

	/* now look for instances of driver on our adapters */
	if (driver->flags & I2C_DF_NOTIFY) {
		list_for_each(item,&adapters) {
			adapter = list_entry(item, struct i2c_adapter, list);
			driver->attach_adapter(adapter);
		}
	}

 out_unlock:
	up(&core_lists);
	return res;
}

int i2c_del_driver(struct i2c_driver *driver)
{
	struct list_head   *item1, *item2, *_n;
	struct i2c_client  *client;
	struct i2c_adapter *adap;
	
	int res = 0;

	down(&core_lists);

	/* Have a look at each adapter, if clients of this driver are still
	 * attached. If so, detach them to be able to kill the driver 
	 * afterwards.
	 */
	pr_debug("i2c-core: unregister_driver - looking for clients.\n");
	/* removing clients does not depend on the notify flag, else 
	 * invalid operation might (will!) result, when using stale client
	 * pointers.
	 */
	list_for_each(item1,&adapters) {
		adap = list_entry(item1, struct i2c_adapter, list);
		dev_dbg(&adap->dev, "examining adapter\n");
		if (driver->detach_adapter) {
			if ((res = driver->detach_adapter(adap))) {
				dev_warn(&adap->dev, "while unregistering "
				       "dummy driver %s, adapter could "
				       "not be detached properly; driver "
				       "not unloaded!",driver->name);
				goto out_unlock;
			}
		} else {
			list_for_each_safe(item2, _n, &adap->clients) {
				client = list_entry(item2, struct i2c_client, list);
				if (client->driver != driver)
					continue;
				pr_debug("i2c-core.o: detaching client %s:\n", client->name);
				if ((res = driver->detach_client(client))) {
					dev_err(&adap->dev, "while "
						"unregistering driver "
						"`%s', the client at "
						"address %02x of "
						"adapter could not "
						"be detached; driver "
						"not unloaded!",
						driver->name,
						client->addr);
					goto out_unlock;
				}
			}
		}
	}

	driver_unregister(&driver->driver);
	list_del(&driver->list);
	pr_debug("i2c-core: driver unregistered: %s\n", driver->name);

 out_unlock:
	up(&core_lists);
	return 0;
}

static int __i2c_check_addr(struct i2c_adapter *adapter, unsigned int addr)
{
	struct list_head   *item;
	struct i2c_client  *client;

	list_for_each(item,&adapter->clients) {
		client = list_entry(item, struct i2c_client, list);
		if (client->addr == addr)
			return -EBUSY;
	}
	return 0;
}

int i2c_check_addr(struct i2c_adapter *adapter, int addr)
{
	int rval;

	down(&adapter->clist_lock);
	rval = __i2c_check_addr(adapter, addr);
	up(&adapter->clist_lock);

	return rval;
}

int i2c_attach_client(struct i2c_client *client)
{
	struct i2c_adapter *adapter = client->adapter;

	down(&adapter->clist_lock);
	if (__i2c_check_addr(client->adapter, client->addr)) {
		up(&adapter->clist_lock);
		return -EBUSY;
	}
	list_add_tail(&client->list,&adapter->clients);
	up(&adapter->clist_lock);
	
	if (adapter->client_register)  {
		if (adapter->client_register(client))  {
			dev_warn(&adapter->dev, "warning: client_register "
				"seems to have failed for client %02x\n",
				client->addr);
		}
	}

	dev_dbg(&adapter->dev, "client [%s] registered to adapter\n",
		client->name);

	if (client->flags & I2C_CLIENT_ALLOW_USE)
		client->usage_count = 0;

	client->dev.parent = &client->adapter->dev;
	client->dev.driver = &client->driver->driver;
	client->dev.bus = &i2c_bus_type;
	client->dev.release = &i2c_client_release;
	
	snprintf(&client->dev.bus_id[0], sizeof(client->dev.bus_id),
		"%d-%04x", i2c_adapter_id(adapter), client->addr);
	pr_debug("registering %s\n", client->dev.bus_id);
	device_register(&client->dev);
	device_create_file(&client->dev, &dev_attr_client_name);
	
	return 0;
}


int i2c_detach_client(struct i2c_client *client)
{
	struct i2c_adapter *adapter = client->adapter;
	int res = 0;
	
	if ((client->flags & I2C_CLIENT_ALLOW_USE) && (client->usage_count > 0))
		return -EBUSY;

	if (adapter->client_unregister)  {
		res = adapter->client_unregister(client);
		if (res) {
			dev_err(&client->dev,
			       "client_unregister [%s] failed, "
			       "client not detached", client->name);
			goto out;
		}
	}

	down(&adapter->clist_lock);
	list_del(&client->list);
	init_completion(&client->released);
	device_remove_file(&client->dev, &dev_attr_client_name);
	device_unregister(&client->dev);
	up(&adapter->clist_lock);
	wait_for_completion(&client->released);

 out:
	return res;
}

static int i2c_inc_use_client(struct i2c_client *client)
{

	if (!try_module_get(client->driver->owner))
		return -ENODEV;
	if (!try_module_get(client->adapter->owner)) {