diff options
| author | Jean Delvare <khali@linux-fr.org> | 2007-07-12 14:12:29 +0200 |
|---|---|---|
| committer | Jean Delvare <khali@hyperion.delvare> | 2007-07-12 14:12:29 +0200 |
| commit | 4b2643d7d9bdcd776749e17f73c168ddf02e93cb (patch) | |
| tree | 1642900ea1c196cc27d120f0af4de44fff30633e /drivers/i2c/i2c-core.c | |
| parent | ba7fbb723f50ab2607989a282af655fb0fab0492 (diff) | |
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-core.c')
| -rw-r--r-- | drivers/i2c/i2c-core.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index cccfa867824..6971a62397d 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -1344,10 +1344,14 @@ s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command, EXPORT_SYMBOL(i2c_smbus_write_block_data); /* Returns the number of read bytes */ -s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command, u8 *values) +s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command, + u8 length, u8 *values) { union i2c_smbus_data data; + if (length > I2C_SMBUS_BLOCK_MAX) + length = I2C_SMBUS_BLOCK_MAX; + data.block[0] = length; if (i2c_smbus_xfer(client->adapter,client->addr,client->flags, I2C_SMBUS_READ,command, I2C_SMBUS_I2C_BLOCK_DATA,&data)) @@ -1468,7 +1472,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, break; case I2C_SMBUS_I2C_BLOCK_DATA: if (read_write == I2C_SMBUS_READ) { - msg[1].len = I2C_SMBUS_BLOCK_MAX; + msg[1].len = data->block[0]; } else { msg[0].len = data->block[0] + 1; if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) { @@ -1524,9 +1528,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, data->word = msgbuf1[0] | (msgbuf1[1] << 8); break; case I2C_SMBUS_I2C_BLOCK_DATA: - /* fixed at 32 for now */ - data->block[0] = I2C_SMBUS_BLOCK_MAX; - for (i = 0; i < I2C_SMBUS_BLOCK_MAX; i++) + for (i = 0; i < data->block[0]; i++) data->block[i+1] = msgbuf1[i]; break; case I2C_SMBUS_BLOCK_DATA: |