Subject: 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 --- Documentation/i2c/chips/max6875 | 2 +- Documentation/i2c/writing-clients | 2 +- drivers/i2c/busses/i2c-powermac.c | 3 +-- drivers/i2c/busses/i2c-viapro.c | 2 +- drivers/i2c/busses/scx200_acb.c | 2 -- drivers/i2c/chips/eeprom.c | 6 ++++-- drivers/i2c/chips/max6875.c | 1 + drivers/i2c/i2c-core.c | 12 +++++++----- drivers/i2c/i2c-dev.c | 9 +++++++++ drivers/macintosh/windfarm_smu_sat.c | 28 ++++------------------------ include/linux/i2c.h | 5 +++-- 11 files changed, 32 insertions(+), 40 deletions(-) --- linux-2.6.22-rc1.orig/drivers/i2c/i2c-core.c 2007-05-15 09:11:47.000000000 +0200 +++ linux-2.6.22-rc1/drivers/i2c/i2c-core.c 2007-05-15 09:11:48.000000000 +0200 @@ -1343,10 +1343,14 @@ s32 i2c_smbus_write_block_data(struct i2 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)) @@ -1467,7 +1471,7 @@ static s32 i2c_smbus_xfer_emulated(struc 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) { @@ -1523,9 +1527,7 @@ static s32 i2c_smbus_xfer_emulated(struc 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: --- linux-2.6.22-rc1.orig/Documentation/i2c/chips/max6875 2007-05-15 09:11:26.000000000 +0200 +++ linux-2.6.22-rc1/Documentation/i2c/chips/max6875 2007-05-15 09:11:48.000000000 +0200 @@ -99,7 +99,7 @@ And then read the data or - count = i2c_smbus_read_i2c_block_data(fd, 0x84, buffer); + count = i2c_smbus_read_i2c_block_data(fd, 0x84, 16, buffer); The block read should read 16 bytes. 0x84 is the block read command. --- linux-2.6.22-rc1.orig/Documentation/i2c/writing-clients 2007-05-15 09:11:26.000000000 +0200 +++ linux-2.6.22-rc1/Documentation/i2c/writing-clients 2007-05-15 09:11:48.000000000 +0200 @@ -571,7 +571,7 @@ SMBus communication u8 command, u8 length, u8 *values); extern s32 i2c_smbus_read_i2c_block_data(struct i2c_client * client, - u8 command, u8 *values); + u8 command, u8 length, u8 *values); These ones were removed in Linux 2.6.10 because they had no users, but could be added back later if needed: --- linux-2.6.22-rc1.orig/drivers/i2c/chips/eeprom.c 2007-05-15 09:11:26.000000000 +0200 +++ linux-2.6.22-rc1/drivers/i2c/chips/eeprom.c 2007-05-15 09:11:48.000000000 +0200 @@ -88,8 +88,10 @@ static void eeprom_update_client(struct dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice); if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { - for (i = slice << 5; i < (slice + 1) << 5; i += I2C_SMBUS_BLOCK_MAX) - if (i2c_smbus_read_i2c_block_data(client, i, data->data + i) != I2C_SMBUS_BLOCK_MAX) + for (i = slice << 5; i < (slice + 1) << 5; i += 32) + if (i2c_smbus_read_i2c_block_data(client, i, + 32, data->data + i) + != 32) goto exit; } else { if (i2c_smbus_write_byte(client, slice << 5)) { --- linux-2.6.22-rc1.orig/drivers/i2c/chips/max6875.c 2007-05-15 09:11:26.000000000 +0200 +++ linux-2.6.22-rc1/drivers/i2c/chips/max6875.c 2007-05-15 09:11:48.000000000 +0200 @@ -106,6 +106,7 @@ static void max6875_update_slice(struct I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { if (i2c_smbus_read_i2c_block_data(client, MAX6875_CMD_BLK_READ, + SLICE_SIZE, buf) != SLICE_SIZE) { goto exit_up; } --- linux-2.6.22-rc1.orig/include/linux/i2c.h 2007-05-15 09:11:47.000000000 +0200 +++ linux-2.6.22-rc1/include/linux/i2c.h 2007-05-15 09:11:48.000000000 +0200 @@ -90,7 +90,7 @@ extern s32 i2c_smbus_write_block_data(st const u8 *values); /* Returns the number of read bytes */ extern s32 i2c_smbus_read_i2c_block_data(struct i2c_client * client, - u8 command, u8 *values); + u8 command, u8 length, u8 *values); extern s32 i2c_smbus_write_i2c_block_data(struct i2c_client * client, u8 command, u8 length, const u8 *values); @@ -524,8 +524,9 @@ union i2c_smbus_data { #define I2C_SMBUS_WORD_DATA 3 #define I2C_SMBUS_PROC_CALL 4 #define I2C_SMBUS_BLOCK_DATA 5 -#define I2C_SMBUS_I2C_BLOCK_DATA 6 +#define I2C_SMBUS_I2C_BLOCK_BROKEN 6 #define I2C_SMBUS_BLOCK_PROC_CALL 7 /* SMBus 2.0 */ +#define I2C_SMBUS_I2C_BLOCK_DATA 8 /* ----- commands for the ioctl like i2c_command call: --- linux-2.6.22-rc1.orig/drivers/macintosh/windfarm_smu_sat.c 2007-05-15 09:11:26.000000000 +0200 +++ linux-2.6.22-rc1/drivers/macintosh/windfarm_smu_sat.c 2007-05-15 09:11:48.000000000 +0200 @@ -67,26 +67,6 @@ static struct i2c_driver wf_sat_driver = .detach_client = wf_sat_detach, }; -/* - * XXX i2c_smbus_read_i2c_block_data doesn't pass the requested - * length down to the low-level driver, so we use this, which - * works well enough with the SMU i2c driver code... - */ -static int sat_read_block(struct i2c_client *client, u8 command, - u8 *values, int len) -{ - union i2c_smbus_data data; - int err; - - data.block[0] = len; - err = i2c_smbus_xfer(client->adapter, client->addr, client->flags, - I2C_SMBUS_READ, command, I2C_SMBUS_I2C_BLOCK_DATA, - &data); - if (!err) - memcpy(values, data.block, len); - return err; -} - struct smu_sdbp_header *smu_sat_get_sdb_partition(unsigned int sat_id, int id, unsigned int *size) { @@ -124,8 +104,8 @@ struct smu_sdbp_header *smu_sat_get_sdb_ return NULL; for (i = 0; i < len; i += 4) { - err = sat_read_block(&sat->i2c, 0xa, data, 4); - if (err) { + err = i2c_smbus_read_i2c_block_data(&sat->i2c, 0xa, 4, data); + if (err < 0) { printk(KERN_ERR "smu_sat_get_sdb_part rd err %d\n", err); goto fail; @@ -157,8 +137,8 @@ static int wf_sat_read_cache(struct wf_s { int err; - err = sat_read_block(&sat->i2c, 0x3f, sat->cache, 16); - if (err) + err = i2c_smbus_read_i2c_block_data(&sat->i2c, 0x3f, 16, sat->cache); + if (err < 0) return err; sat->last_read = jiffies; #ifdef LOTSA_DEBUG --- linux-2.6.22-rc1.orig/drivers/i2c/busses/i2c-powermac.c 2007-05-15 09:11:26.000000000 +0200 +++ linux-2.6.22-rc1/drivers/i2c/busses/i2c-powermac.c 2007-05-15 09:11:48.000000000 +0200 @@ -121,8 +121,7 @@ static s32 i2c_powermac_smbus_xfer( stru if (rc) goto bail; rc = pmac_i2c_xfer(bus, addrdir, 1, command, - read ? data->block : &data->block[1], - data->block[0]); + &data->block[1], data->block[0]); break; default: --- linux-2.6.22-rc1.orig/drivers/i2c/busses/i2c-viapro.c 2007-05-15 09:11:26.000000000 +0200 +++ linux-2.6.22-rc1/drivers/i2c/busses/i2c-viapro.c 2007-05-15 09:11:48.000000000 +0200 @@ -235,7 +235,7 @@ static s32 vt596_access(struct i2c_adapt if (!(vt596_features & FEATURE_I2CBLOCK)) goto exit_unsupported; if (read_write == I2C_SMBUS_READ) - outb_p(I2C_SMBUS_BLOCK_MAX, SMBHSTDAT0); + outb_p(data->block[0], SMBHSTDAT0); /* Fall through */ case I2C_SMBUS_BLOCK_DATA: outb_p(command, SMBHSTCMD); --- linux-2.6.22-rc1.orig/drivers/i2c/busses/scx200_acb.c 2007-05-15 09:11:44.000000000 +0200 +++ linux-2.6.22-rc1/drivers/i2c/busses/scx200_acb.c 2007-05-15 09:11:48.000000000 +0200 @@ -310,8 +310,6 @@ static s32 scx200_acb_smbus_xfer(struct break; case I2C_SMBUS_I2C_BLOCK_DATA: - if (rw == I2C_SMBUS_READ) - data->block[0] = I2C_SMBUS_BLOCK_MAX; /* For now */ len = data->block[0]; if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) return -EINVAL; --- linux-2.6.22-rc1.orig/drivers/i2c/i2c-dev.c 2007-05-15 09:11:26.000000000 +0200 +++ linux-2.6.22-rc1/drivers/i2c/i2c-dev.c 2007-05-15 10:31:25.000000000 +0200 @@ -283,6 +283,7 @@ static int i2cdev_ioctl(struct inode *in (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 *in 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);