i2c: Fix the i2c_smbus_read_i2c_block_data() prototype
Jean Delvare [Thu, 12 Jul 2007 12:12:29 +0000 (14:12 +0200)]
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>

Documentation/i2c/chips/max6875
Documentation/i2c/writing-clients
drivers/i2c/busses/i2c-powermac.c
drivers/i2c/busses/i2c-viapro.c
drivers/i2c/busses/scx200_acb.c
drivers/i2c/chips/eeprom.c
drivers/i2c/chips/max6875.c
drivers/i2c/i2c-core.c
drivers/i2c/i2c-dev.c
drivers/macintosh/windfarm_smu_sat.c
include/linux/i2c.h

index 96fec56..a0cd8af 100644 (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.
index 3d8d36b..2c17003 100644 (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:
index 1425d22..0ab4f26 100644 (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:
index 7a2bc06..a0f7e4a 100644 (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);
index dc64f8b..e6c4a2b 100644 (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;
index bfce13c..48f857a 100644 (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)) {
index 76645c1..e9e9e51 100644 (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;
                        }
index cccfa86..6971a62 100644 (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:
index e7a7097..64eee95 100644 (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);
index 1043b39..351982b 100644 (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
index 44f2ecf..2eaba21 100644 (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: