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i2c: Fix the i2c_smbus_read_i2c_block_data() prototype

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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>
This commit is contained in:
Jean Delvare 2007-07-12 14:12:29 +02:00 committed by Jean Delvare
parent ba7fbb723f
commit 4b2643d7d9
11 changed files with 32 additions and 40 deletions
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2
Documentation/i2c/chips/max6875
View file

@ -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.

2
Documentation/i2c/writing-clients
View file

@ -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:

3
drivers/i2c/busses/i2c-powermac.c
View file

@ -121,8 +121,7 @@ static s32 i2c_powermac_smbus_xfer( struct i2c_adapter* adap,
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:

2
drivers/i2c/busses/i2c-viapro.c
View file

@ -235,7 +235,7 @@ static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
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);

2
drivers/i2c/busses/scx200_acb.c
View file

@ -310,8 +310,6 @@ static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter,
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;

6
drivers/i2c/chips/eeprom.c
View file

@ -88,8 +88,10 @@ static void eeprom_update_client(struct i2c_client *client, u8 slice)
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)) {

1
drivers/i2c/chips/max6875.c
View file

@ -106,6 +106,7 @@ static void max6875_update_slice(struct i2c_client *client, int slice)
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;
}

12
drivers/i2c/i2c-core.c
View file

@ -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:

9
drivers/i2c/i2c-dev.c
View file

@ -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);

28
drivers/macintosh/windfarm_smu_sat.c
View file

@ -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_partition(unsigned int sat_id, int id,
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_sat *sat)
{
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

5
include/linux/i2c.h
View file

@ -90,7 +90,7 @@ extern s32 i2c_smbus_write_block_data(struct i2c_client * client,
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: