i2c-core.c

i2c-core.c - a device driver for the iic-bus interface

/* 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]> 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 <asm/uaccess.h>


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

/* match always succeeds, as we want the probe() to tell if we really accept this match */
static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
	return 1;
}

static int i2c_bus_suspend(struct device * dev, pm_message_t state)
{
	int rc = 0;

	if (dev->driver && dev->driver->suspend)
		rc = dev->driver->suspend(dev, state);
	return rc;
}

static int i2c_bus_resume(struct device * dev)
{
	int rc = 0;
	
	if (dev->driver && dev->driver->resume)
		rc = dev->driver->resume(dev);
	return rc;
}

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

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

struct bus_type i2c_bus_type = {
	.name =		"i2c",
	.match =	i2c_device_match,
	.probe =	i2c_device_probe,
	.remove =	i2c_device_remove,
	.suspend =      i2c_bus_suspend,
	.resume =       i2c_bus_resume,
};

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

struct device_driver i2c_adapter_driver = {
	.owner = THIS_MODULE,
	.name =	"i2c_adapter",
	.bus = &i2c_bus_type,
};

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);
}

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

static ssize_t show_adapter_name(struct device *dev, struct device_attribute *attr, 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, struct device_attribute *attr, 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;

	mutex_lock(&core_lists);

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

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

	adap->nr =  id & MAX_ID_MASK;
	mutex_init(&adap->bus_lock);
	mutex_init(&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;
	res = device_register(&adap->dev);
	if (res)
		goto out_list;
	res = device_create_file(&adap->dev, &dev_attr_name);
	if (res)
		goto out_unregister;

	/* 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);
	res = class_device_register(&adap->class_dev);
	if (res)
		goto out_remove_name;

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

	/* inform drivers of new adapters */
	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_remove_name:
	device_remove_file(&adap->dev, &dev_attr_name);
out_unregister:
	init_completion(&adap->dev_released); /* Needed? */
	device_unregister(&adap->dev);
	wait_for_completion(&adap->dev_released);
out_list:
	list_del(&adap->list);
	idr_remove(&i2c_adapter_idr, adap->nr);
	goto out_unlock;
}


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) {
		client = list_entry(item, struct i2c_client, list);

		if ((res=client->driver->detach_client(client))) {
			dev_err(&adap->dev, "detach_client failed for client "
				"[%s] at address 0x%02x\n", client->name,
				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 [%s] unregistered\n", adap->name);

 out_unlock:
	mutex_unlock(&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_register_driver(struct module *owner, struct i2c_driver *driver)
{
	struct list_head   *item;
	struct i2c_adapter *adapter;
	int res;

	/* add the driver to the list of i2c drivers in the driver core */
	driver->driver.owner = owner;
	driver->driver.bus = &i2c_bus_type;

	res = driver_register(&driver->driver);
	if (res)
		return res;
	
	mutex_lock(&core_lists);

	list_add_tail(&driver->list,&drivers);
	pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);

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

	mutex_unlock(&core_lists);
	return 0;
}
EXPORT_SYMBOL(i2c_register_driver);

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;

	mutex_lock(&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.
	 */
	list_for_each(item1,&adapters) {
		adap = list_entry(item1, struct i2c_adapter, 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;
			}
		} else {
			list_for_each_safe(item2, _n, &adap->clients) {
				client = list_entry(item2, struct i2c_client, list);
				if (client->driver != driver)
					continue;
				dev_dbg(&adap->dev, "detaching client [%s] "
					"at 0x%02x\n", client->name,
					client->addr);
				if ((res = driver->detach_client(client))) {
					dev_err(&adap->dev, "detach_client "
						"failed for client [%s] at "
						"0x%02x\n", client->name,
						client->addr);
					goto out_unlock;
				}
			}
		}
	}

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

 out_unlock:
	mutex_unlock(&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;