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authorJean Delvare <khali@linux-fr.org>2007-07-12 08:12:29 -0400
committerJean Delvare <khali@hyperion.delvare>2007-07-12 08:12:29 -0400
commit4b2643d7d9bdcd776749e17f73c168ddf02e93cb (patch)
tree1642900ea1c196cc27d120f0af4de44fff30633e /drivers/i2c/i2c-core.c
parentba7fbb723f50ab2607989a282af655fb0fab0492 (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.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index cccfa8678245..6971a62397db 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,
1344EXPORT_SYMBOL(i2c_smbus_write_block_data); 1344EXPORT_SYMBOL(i2c_smbus_write_block_data);
1345 1345
1346/* Returns the number of read bytes */ 1346/* Returns the number of read bytes */
1347s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command, u8 *values) 1347s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
1348 u8 length, u8 *values)
1348{ 1349{
1349 union i2c_smbus_data data; 1350 union i2c_smbus_data data;
1350 1351
1352 if (length > I2C_SMBUS_BLOCK_MAX)
1353 length = I2C_SMBUS_BLOCK_MAX;
1354 data.block[0] = length;
1351 if (i2c_smbus_xfer(client->adapter,client->addr,client->flags, 1355 if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
1352 I2C_SMBUS_READ,command, 1356 I2C_SMBUS_READ,command,
1353 I2C_SMBUS_I2C_BLOCK_DATA,&data)) 1357 I2C_SMBUS_I2C_BLOCK_DATA,&data))
@@ -1468,7 +1472,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr,
1468 break; 1472 break;
1469 case I2C_SMBUS_I2C_BLOCK_DATA: 1473 case I2C_SMBUS_I2C_BLOCK_DATA:
1470 if (read_write == I2C_SMBUS_READ) { 1474 if (read_write == I2C_SMBUS_READ) {
1471 msg[1].len = I2C_SMBUS_BLOCK_MAX; 1475 msg[1].len = data->block[0];
1472 } else { 1476 } else {
1473 msg[0].len = data->block[0] + 1; 1477 msg[0].len = data->block[0] + 1;
1474 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) { 1478 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,
1524 data->word = msgbuf1[0] | (msgbuf1[1] << 8); 1528 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
1525 break; 1529 break;
1526 case I2C_SMBUS_I2C_BLOCK_DATA: 1530 case I2C_SMBUS_I2C_BLOCK_DATA:
1527 /* fixed at 32 for now */ 1531 for (i = 0; i < data->block[0]; i++)
1528 data->block[0] = I2C_SMBUS_BLOCK_MAX;
1529 for (i = 0; i < I2C_SMBUS_BLOCK_MAX; i++)
1530 data->block[i+1] = msgbuf1[i]; 1532 data->block[i+1] = msgbuf1[i];
1531 break; 1533 break;
1532 case I2C_SMBUS_BLOCK_DATA: 1534 case I2C_SMBUS_BLOCK_DATA: