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authorJean Delvare <khali@linux-fr.org>2007-07-12 14:12:29 +0200
committerJean Delvare <khali@hyperion.delvare>2007-07-12 14:12:29 +0200
commit4b2643d7d9bdcd776749e17f73c168ddf02e93cb (patch)
tree1642900ea1c196cc27d120f0af4de44fff30633e /drivers/i2c/i2c-dev.c
parentba7fbb723f50ab2607989a282af655fb0fab0492 (diff)
downloadblackbird-op-linux-4b2643d7d9bdcd776749e17f73c168ddf02e93cb.tar.gz
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i2c: Fix the i2c_smbus_read_i2c_block_data() prototype
Let the drivers specify how many bytes they want to read with i2c_smbus_read_i2c_block_data(). So far, the block count was hard-coded to I2C_SMBUS_BLOCK_MAX (32), which did not make much sense. Many driver authors complained about this before, and I believe it's about time to fix it. Right now, authors have to do technically stupid things, such as individual byte reads or full-fledged I2C messaging, to work around the problem. We do not want to encourage that. I even found that some bus drivers (e.g. i2c-amd8111) already implemented I2C block read the "right" way, that is, they didn't follow the old, broken standard. The fact that it was never noticed before just shows how little i2c_smbus_read_i2c_block_data() was used, which isn't that surprising given how broken its prototype was so far. There are some obvious compatiblity considerations: * This changes the i2c_smbus_read_i2c_block_data() prototype. Users outside the kernel tree will notice at compilation time, and will have to update their code. * User-space has access to i2c_smbus_xfer() directly using i2c-dev, so the changed expectations would affect tools such as i2cdump. In order to preserve binary compatibility, we give I2C_SMBUS_I2C_BLOCK_DATA a new numeric value, and define I2C_SMBUS_I2C_BLOCK_BROKEN with the old numeric value. When i2c-dev receives a transaction with the old value, it can convert it to the new format on the fly. Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'drivers/i2c/i2c-dev.c')
-rw-r--r--drivers/i2c/i2c-dev.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index e7a709710592..64eee9551b22 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -283,6 +283,7 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
(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,
@@ -329,10 +330,18 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
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);
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