linux/drivers/i2c/i2c-dev.c
David Brownell 9b766b814d i2c: Stop using the redundant client list
The i2c_adapter.clients list of i2c_client nodes duplicates driver
model state.  This patch starts removing that list, letting us remove
most existing users of those i2c-core lists.

 * The core I2C code now iterates over the driver model's list instead
   of the i2c-internal one in some places where it's safe:
      - Passing a command/ioctl to each client, a mechanims
        used almost exclusively by DVB adapters;
      - Device address checking, in both i2c-core and i2c-dev.

 * Provide i2c_verify_client() to use with driver model iterators.

 * Flag the relevant i2c_adapter and i2c_client fields as deprecated,
   to help prevent new users from appearing.

For the moment the list needs to stick around, since some issues show
up when deleting devices created by legacy I2C drivers.  (They don't
follow standard driver model rules.  Removing those devices can cause
self-deadlocks.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-01-27 18:14:51 +01:00

609 lines
17 KiB
C

/*
i2c-dev.c - i2c-bus driver, char device interface
Copyright (C) 1995-97 Simon G. Vogl
Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
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.
*/
/* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
But I have used so much of his original code and ideas that it seems
only fair to recognize him as co-author -- Frodo */
/* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <asm/uaccess.h>
static struct i2c_driver i2cdev_driver;
/*
* An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
* slave (i2c_client) with which messages will be exchanged. It's coupled
* with a character special file which is accessed by user mode drivers.
*
* The list of i2c_dev structures is parallel to the i2c_adapter lists
* maintained by the driver model, and is updated using notifications
* delivered to the i2cdev_driver.
*/
struct i2c_dev {
struct list_head list;
struct i2c_adapter *adap;
struct device *dev;
};
#define I2C_MINORS 256
static LIST_HEAD(i2c_dev_list);
static DEFINE_SPINLOCK(i2c_dev_list_lock);
static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
{
struct i2c_dev *i2c_dev;
spin_lock(&i2c_dev_list_lock);
list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
if (i2c_dev->adap->nr == index)
goto found;
}
i2c_dev = NULL;
found:
spin_unlock(&i2c_dev_list_lock);
return i2c_dev;
}
static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
{
struct i2c_dev *i2c_dev;
if (adap->nr >= I2C_MINORS) {
printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
adap->nr);
return ERR_PTR(-ENODEV);
}
i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
if (!i2c_dev)
return ERR_PTR(-ENOMEM);
i2c_dev->adap = adap;
spin_lock(&i2c_dev_list_lock);
list_add_tail(&i2c_dev->list, &i2c_dev_list);
spin_unlock(&i2c_dev_list_lock);
return i2c_dev;
}
static void return_i2c_dev(struct i2c_dev *i2c_dev)
{
spin_lock(&i2c_dev_list_lock);
list_del(&i2c_dev->list);
spin_unlock(&i2c_dev_list_lock);
kfree(i2c_dev);
}
static ssize_t show_adapter_name(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
if (!i2c_dev)
return -ENODEV;
return sprintf(buf, "%s\n", i2c_dev->adap->name);
}
static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
/* ------------------------------------------------------------------------- */
/*
* After opening an instance of this character special file, a file
* descriptor starts out associated only with an i2c_adapter (and bus).
*
* Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
* traffic to any devices on the bus used by that adapter. That's because
* the i2c_msg vectors embed all the addressing information they need, and
* are submitted directly to an i2c_adapter. However, SMBus-only adapters
* don't support that interface.
*
* To use read()/write() system calls on that file descriptor, or to use
* SMBus interfaces (and work with SMBus-only hosts!), you must first issue
* an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl. That configures an anonymous
* (never registered) i2c_client so it holds the addressing information
* needed by those system calls and by this SMBus interface.
*/
static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count,
loff_t *offset)
{
char *tmp;
int ret;
struct i2c_client *client = (struct i2c_client *)file->private_data;
if (count > 8192)
count = 8192;
tmp = kmalloc(count,GFP_KERNEL);
if (tmp==NULL)
return -ENOMEM;
pr_debug("i2c-dev: i2c-%d reading %zd bytes.\n",
iminor(file->f_path.dentry->d_inode), count);
ret = i2c_master_recv(client,tmp,count);
if (ret >= 0)
ret = copy_to_user(buf,tmp,count)?-EFAULT:ret;
kfree(tmp);
return ret;
}
static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t count,
loff_t *offset)
{
int ret;
char *tmp;
struct i2c_client *client = (struct i2c_client *)file->private_data;
if (count > 8192)
count = 8192;
tmp = kmalloc(count,GFP_KERNEL);
if (tmp==NULL)
return -ENOMEM;
if (copy_from_user(tmp,buf,count)) {
kfree(tmp);
return -EFAULT;
}
pr_debug("i2c-dev: i2c-%d writing %zd bytes.\n",
iminor(file->f_path.dentry->d_inode), count);
ret = i2c_master_send(client,tmp,count);
kfree(tmp);
return ret;
}
static int i2cdev_check(struct device *dev, void *addrp)
{
struct i2c_client *client = i2c_verify_client(dev);
if (!client || client->addr != *(unsigned int *)addrp)
return 0;
return dev->driver ? -EBUSY : 0;
}
/* This address checking function differs from the one in i2c-core
in that it considers an address with a registered device, but no
driver bound to it, as NOT busy. */
static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
{
return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
}
static int i2cdev_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
struct i2c_client *client = (struct i2c_client *)file->private_data;
struct i2c_rdwr_ioctl_data rdwr_arg;
struct i2c_smbus_ioctl_data data_arg;
union i2c_smbus_data temp;
struct i2c_msg *rdwr_pa;
u8 __user **data_ptrs;
int i,datasize,res;
unsigned long funcs;
dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
cmd, arg);
switch ( cmd ) {
case I2C_SLAVE:
case I2C_SLAVE_FORCE:
/* NOTE: devices set up to work with "new style" drivers
* can't use I2C_SLAVE, even when the device node is not
* bound to a driver. Only I2C_SLAVE_FORCE will work.
*
* Setting the PEC flag here won't affect kernel drivers,
* which will be using the i2c_client node registered with
* the driver model core. Likewise, when that client has
* the PEC flag already set, the i2c-dev driver won't see
* (or use) this setting.
*/
if ((arg > 0x3ff) ||
(((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
return -EINVAL;
if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
return -EBUSY;
/* REVISIT: address could become busy later */
client->addr = arg;
return 0;
case I2C_TENBIT:
if (arg)
client->flags |= I2C_M_TEN;
else
client->flags &= ~I2C_M_TEN;
return 0;
case I2C_PEC:
if (arg)
client->flags |= I2C_CLIENT_PEC;
else
client->flags &= ~I2C_CLIENT_PEC;
return 0;
case I2C_FUNCS:
funcs = i2c_get_functionality(client->adapter);
return put_user(funcs, (unsigned long __user *)arg);
case I2C_RDWR:
if (copy_from_user(&rdwr_arg,
(struct i2c_rdwr_ioctl_data __user *)arg,
sizeof(rdwr_arg)))
return -EFAULT;
/* Put an arbitrary limit on the number of messages that can
* be sent at once */
if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
return -EINVAL;
rdwr_pa = (struct i2c_msg *)
kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg),
GFP_KERNEL);
if (rdwr_pa == NULL) return -ENOMEM;
if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
kfree(rdwr_pa);
return -EFAULT;
}
data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
if (data_ptrs == NULL) {
kfree(rdwr_pa);
return -ENOMEM;
}
res = 0;
for( i=0; i<rdwr_arg.nmsgs; i++ ) {
/* Limit the size of the message to a sane amount;
* and don't let length change either. */
if ((rdwr_pa[i].len > 8192) ||
(rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
res = -EINVAL;
break;
}
data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
if(rdwr_pa[i].buf == NULL) {
res = -ENOMEM;
break;
}
if(copy_from_user(rdwr_pa[i].buf,
data_ptrs[i],
rdwr_pa[i].len)) {
++i; /* Needs to be kfreed too */
res = -EFAULT;
break;
}
}
if (res < 0) {
int j;
for (j = 0; j < i; ++j)
kfree(rdwr_pa[j].buf);
kfree(data_ptrs);
kfree(rdwr_pa);
return res;
}
res = i2c_transfer(client->adapter,
rdwr_pa,
rdwr_arg.nmsgs);
while(i-- > 0) {
if( res>=0 && (rdwr_pa[i].flags & I2C_M_RD)) {
if(copy_to_user(
data_ptrs[i],
rdwr_pa[i].buf,
rdwr_pa[i].len)) {
res = -EFAULT;
}
}
kfree(rdwr_pa[i].buf);
}
kfree(data_ptrs);
kfree(rdwr_pa);
return res;
case I2C_SMBUS:
if (copy_from_user(&data_arg,
(struct i2c_smbus_ioctl_data __user *) arg,
sizeof(struct i2c_smbus_ioctl_data)))
return -EFAULT;
if ((data_arg.size != I2C_SMBUS_BYTE) &&
(data_arg.size != I2C_SMBUS_QUICK) &&
(data_arg.size != I2C_SMBUS_BYTE_DATA) &&
(data_arg.size != I2C_SMBUS_WORD_DATA) &&
(data_arg.size != I2C_SMBUS_PROC_CALL) &&
(data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
(data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
(data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
(data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
dev_dbg(&client->adapter->dev,
"size out of range (%x) in ioctl I2C_SMBUS.\n",
data_arg.size);
return -EINVAL;
}
/* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
so the check is valid if size==I2C_SMBUS_QUICK too. */
if ((data_arg.read_write != I2C_SMBUS_READ) &&
(data_arg.read_write != I2C_SMBUS_WRITE)) {
dev_dbg(&client->adapter->dev,
"read_write out of range (%x) in ioctl I2C_SMBUS.\n",
data_arg.read_write);
return -EINVAL;
}
/* Note that command values are always valid! */
if ((data_arg.size == I2C_SMBUS_QUICK) ||
((data_arg.size == I2C_SMBUS_BYTE) &&
(data_arg.read_write == I2C_SMBUS_WRITE)))
/* These are special: we do not use data */
return i2c_smbus_xfer(client->adapter, client->addr,
client->flags,
data_arg.read_write,
data_arg.command,
data_arg.size, NULL);
if (data_arg.data == NULL) {
dev_dbg(&client->adapter->dev,
"data is NULL pointer in ioctl I2C_SMBUS.\n");
return -EINVAL;
}
if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
(data_arg.size == I2C_SMBUS_BYTE))
datasize = sizeof(data_arg.data->byte);
else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
(data_arg.size == I2C_SMBUS_PROC_CALL))
datasize = sizeof(data_arg.data->word);
else /* size == smbus block, i2c block, or block proc. call */
datasize = sizeof(data_arg.data->block);
if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
(data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
(data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
(data_arg.read_write == I2C_SMBUS_WRITE)) {
if (copy_from_user(&temp, data_arg.data, datasize))
return -EFAULT;
}
if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
/* Convert old I2C block commands to the new
convention. This preserves binary compatibility. */
data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
if (data_arg.read_write == I2C_SMBUS_READ)
temp.block[0] = I2C_SMBUS_BLOCK_MAX;
}
res = i2c_smbus_xfer(client->adapter,client->addr,client->flags,
data_arg.read_write,
data_arg.command,data_arg.size,&temp);
if (! res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
(data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
(data_arg.read_write == I2C_SMBUS_READ))) {
if (copy_to_user(data_arg.data, &temp, datasize))
return -EFAULT;
}
return res;
case I2C_RETRIES:
client->adapter->retries = arg;
break;
case I2C_TIMEOUT:
client->adapter->timeout = arg;
break;
default:
/* NOTE: returning a fault code here could cause trouble
* in buggy userspace code. Some old kernel bugs returned
* zero in this case, and userspace code might accidentally
* have depended on that bug.
*/
return -ENOTTY;
}
return 0;
}
static int i2cdev_open(struct inode *inode, struct file *file)
{
unsigned int minor = iminor(inode);
struct i2c_client *client;
struct i2c_adapter *adap;
struct i2c_dev *i2c_dev;
i2c_dev = i2c_dev_get_by_minor(minor);
if (!i2c_dev)
return -ENODEV;
adap = i2c_get_adapter(i2c_dev->adap->nr);
if (!adap)
return -ENODEV;
/* This creates an anonymous i2c_client, which may later be
* pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
*
* This client is ** NEVER REGISTERED ** with the driver model
* or I2C core code!! It just holds private copies of addressing
* information and maybe a PEC flag.
*/
client = kzalloc(sizeof(*client), GFP_KERNEL);
if (!client) {
i2c_put_adapter(adap);
return -ENOMEM;
}
snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
client->driver = &i2cdev_driver;
client->adapter = adap;
file->private_data = client;
return 0;
}
static int i2cdev_release(struct inode *inode, struct file *file)
{
struct i2c_client *client = file->private_data;
i2c_put_adapter(client->adapter);
kfree(client);
file->private_data = NULL;
return 0;
}
static const struct file_operations i2cdev_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.read = i2cdev_read,
.write = i2cdev_write,
.ioctl = i2cdev_ioctl,
.open = i2cdev_open,
.release = i2cdev_release,
};
/* ------------------------------------------------------------------------- */
/*
* The legacy "i2cdev_driver" is used primarily to get notifications when
* I2C adapters are added or removed, so that each one gets an i2c_dev
* and is thus made available to userspace driver code.
*/
static struct class *i2c_dev_class;
static int i2cdev_attach_adapter(struct i2c_adapter *adap)
{
struct i2c_dev *i2c_dev;
int res;
i2c_dev = get_free_i2c_dev(adap);
if (IS_ERR(i2c_dev))
return PTR_ERR(i2c_dev);
/* register this i2c device with the driver core */
i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
MKDEV(I2C_MAJOR, adap->nr),
"i2c-%d", adap->nr);
if (IS_ERR(i2c_dev->dev)) {
res = PTR_ERR(i2c_dev->dev);
goto error;
}
res = device_create_file(i2c_dev->dev, &dev_attr_name);
if (res)
goto error_destroy;
pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
adap->name, adap->nr);
return 0;
error_destroy:
device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
error:
return_i2c_dev(i2c_dev);
return res;
}
static int i2cdev_detach_adapter(struct i2c_adapter *adap)
{
struct i2c_dev *i2c_dev;
i2c_dev = i2c_dev_get_by_minor(adap->nr);
if (!i2c_dev) /* attach_adapter must have failed */
return 0;
device_remove_file(i2c_dev->dev, &dev_attr_name);
return_i2c_dev(i2c_dev);
device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
return 0;
}
static int i2cdev_detach_client(struct i2c_client *client)
{
return 0;
}
static struct i2c_driver i2cdev_driver = {
.driver = {
.name = "dev_driver",
},
.id = I2C_DRIVERID_I2CDEV,
.attach_adapter = i2cdev_attach_adapter,
.detach_adapter = i2cdev_detach_adapter,
.detach_client = i2cdev_detach_client,
};
/* ------------------------------------------------------------------------- */
/*
* module load/unload record keeping
*/
static int __init i2c_dev_init(void)
{
int res;
printk(KERN_INFO "i2c /dev entries driver\n");
res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
if (res)
goto out;
i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
if (IS_ERR(i2c_dev_class))
goto out_unreg_chrdev;
res = i2c_add_driver(&i2cdev_driver);
if (res)
goto out_unreg_class;
return 0;
out_unreg_class:
class_destroy(i2c_dev_class);
out_unreg_chrdev:
unregister_chrdev(I2C_MAJOR, "i2c");
out:
printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
return res;
}
static void __exit i2c_dev_exit(void)
{
i2c_del_driver(&i2cdev_driver);
class_destroy(i2c_dev_class);
unregister_chrdev(I2C_MAJOR,"i2c");
}
MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
"Simon G. Vogl <simon@tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C /dev entries driver");
MODULE_LICENSE("GPL");
module_init(i2c_dev_init);
module_exit(i2c_dev_exit);