- 根目录:
- drivers
- i2c
- i2c-dev.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/device.h>
#include <linux/notifier.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 <linux/jiffies.h>
#include <linux/uaccess.h>
/*
* 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 bus notifications.
*/
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 = 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 %zu 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 = file->private_data;
if (count > 8192)
count = 8192;
tmp = memdup_user(buf, count);
if (IS_ERR(tmp))
return PTR_ERR(tmp);
pr_debug("i2c-dev: i2c-%d writing %zu 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;
}
/* walk up mux tree */
static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
{
struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
int result;
result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
if (!result && parent)
result = i2cdev_check_mux_parents(parent, addr);
return result;
}
/* recurse down mux tree */
static int i2cdev_check_mux_children(struct device *dev, void *addrp)
{
int result;
if (dev->type == &i2c_adapter_type)
result = device_for_each_child(dev, addrp,
i2cdev_check_mux_children);
else
result = i2cdev_check(dev, addrp);
return result;
}
/* 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)
{
struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
int result = 0;
if (parent)
result = i2cdev_check_mux_parents(parent, addr);
if (!result)
result = device_for_each_child(&adapter->dev, &addr,
i2cdev_check_mux_children);
return result;
}
static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
unsigned long arg)
{
struct i2c_rdwr_ioctl_data rdwr_arg;
struct i2c_msg *rdwr_pa;
u8 __user **data_ptrs;
int i, res;
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 = kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg), GFP_KERNEL);
if (!rdwr_pa)
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 = memdup_user(data_ptrs[i], rdwr_pa[i].len);
if (IS_ERR(rdwr_pa[i].buf)) {
res = PTR_ERR(rdwr_pa[i].buf);
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;
}
static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
unsigned long arg)
{
struct i2c_smbus_ioctl_data data_arg;
union i2c_smbus_data temp;
int datasize, res;
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;
}
static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct i2c_client *client = file->private_data;
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:
return i2cdev_ioctl_rdrw(client, arg);
case I2C_SMBUS:
return i2cdev_ioctl_smbus(client, arg);
case I2C_RETRIES:
client->adapter->retries = arg;
break;
case I2C_TIMEOUT:
/* For historical reasons, user-space sets the timeout
* value in units of 10 ms.
*/
client->adapter->timeout = msecs_to_jiffies(arg * 10);
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->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,
.unlocked_ioctl = i2cdev_ioctl,
.open = i2cdev_open,
.release = i2cdev_release,
};
/* ------------------------------------------------------------------------- */
static struct class *i2c_dev_class;
static int i2cdev_attach_adapter(struct device *dev, void *dummy)
{
struct i2c_adapter *adap;
struct i2c_dev *i2c_dev;
int res;
if (dev->type != &i2c_adapter_type)
return 0;
adap = to_i2c_adapter(dev);
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), NULL,
"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 device *dev, void *dummy)
{
struct i2c_adapter *adap;
struct i2c_dev *i2c_dev;
if (dev->type != &i2c_adapter_type)
return 0;
adap = to_i2c_adapter(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;
}
int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
void *data)
{
struct device *dev = data;
switch (action) {
case BUS_NOTIFY_ADD_DEVICE:
return i2cdev_attach_adapter(dev, NULL);
case BUS_NOTIFY_DEL_DEVICE:
return i2cdev_detach_adapter(dev, NULL);
}
return 0;
}
static struct notifier_block i2cdev_notifier = {
.notifier_call = i2cdev_notifier_call,
};
/* ------------------------------------------------------------------------- */
/*
* 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)) {
res = PTR_ERR(i2c_dev_class);
goto out_unreg_chrdev;
}
/* Keep track of adapters which will be added or removed later */
res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
if (res)
goto out_unreg_class;
/* Bind to already existing adapters right away */
i2c_for_each_dev(NULL, i2cdev_attach_adapter);
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)
{
bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
i2c_for_each_dev(NULL, i2cdev_detach_adapter);
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);