i2c-powermac: Refactor i2c_powermac_smbus_xfer

I wanted to add some error logging to the i2c-powermac driver, but
found that it was very difficult due to the way the
i2c_powermac_smbus_xfer function is organized. Refactor the code in
this function so that each low-level function is only called once.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Michel Daenzer <michel@daenzer.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>

1 files changed, 41 insertions, 44 deletions

diff --git a/drivers/i2c/busses/i2c-powermac.c b/drivers/i2c/busses/i2c-powermac.c
index a74f3bab05b8..dba8e387f43f 100644
--- a/drivers/i2c/busses/i2c-powermac.c
+++ b/drivers/i2c/busses/i2c-powermac.c
@@ -49,48 +49,38 @@ static s32 i2c_powermac_smbus_xfer(	struct i2c_adapter*	adap,
         int                     rc = 0;
         int                     read = (read_write == I2C_SMBUS_READ);
         int                     addrdir = (addr << 1) | read;
+        int                     mode, subsize, len;
+        u32                     subaddr;
+        u8                      *buf;
         u8                      local[2];
 
-        rc = pmac_i2c_open(bus, 0);
-        if (rc)
-                return rc;
+        if (size == I2C_SMBUS_QUICK || size == I2C_SMBUS_BYTE) {
+                mode = pmac_i2c_mode_std;
+                subsize = 0;
+                subaddr = 0;
+        } else {
+                mode = read ? pmac_i2c_mode_combined : pmac_i2c_mode_stdsub;
+                subsize = 1;
+                subaddr = command;
+        }
 
         switch (size) {
         case I2C_SMBUS_QUICK:
-                rc = pmac_i2c_setmode(bus, pmac_i2c_mode_std);
-                if (rc)
-                        goto bail;
-                rc = pmac_i2c_xfer(bus, addrdir, 0, 0, NULL, 0);
+                buf = NULL;
+                len = 0;
                 break;
         case I2C_SMBUS_BYTE:
-                rc = pmac_i2c_setmode(bus, pmac_i2c_mode_std);
-                if (rc)
-                        goto bail;
-                rc = pmac_i2c_xfer(bus, addrdir, 0, 0, &data->byte, 1);
-                break;
         case I2C_SMBUS_BYTE_DATA:
-                rc = pmac_i2c_setmode(bus, read ?
-                                      pmac_i2c_mode_combined :
-                                      pmac_i2c_mode_stdsub);
-                if (rc)
-                        goto bail;
-                rc = pmac_i2c_xfer(bus, addrdir, 1, command, &data->byte, 1);
+                buf = &data->byte;
+                len = 1;
                 break;
         case I2C_SMBUS_WORD_DATA:
-                rc = pmac_i2c_setmode(bus, read ?
-                                      pmac_i2c_mode_combined :
-                                      pmac_i2c_mode_stdsub);
-                if (rc)
-                        goto bail;
                 if (!read) {
                         local[0] = data->word & 0xff;
                         local[1] = (data->word >> 8) & 0xff;
                 }
-                rc = pmac_i2c_xfer(bus, addrdir, 1, command, local, 2);
-                if (rc == 0 && read) {
-                        data->word = ((u16)local[1]) << 8;
-                        data->word |= local[0];
-                }
+                buf = local;
+                len = 2;
                 break;
 
         /* Note that these are broken vs. the expected smbus API where
@@ -105,28 +95,35 @@ static s32 i2c_powermac_smbus_xfer(	struct i2c_adapter*	adap,
          * a repeat start/addr phase (but not stop in between)
          */
         case I2C_SMBUS_BLOCK_DATA:
-                rc = pmac_i2c_setmode(bus, read ?
-                                      pmac_i2c_mode_combined :
-                                      pmac_i2c_mode_stdsub);
-                if (rc)
-                        goto bail;
-                rc = pmac_i2c_xfer(bus, addrdir, 1, command, data->block,
-                                   data->block[0] + 1);
-
+                buf = data->block;
+                len = data->block[0] + 1;
                 break;
         case I2C_SMBUS_I2C_BLOCK_DATA:
-                rc = pmac_i2c_setmode(bus, read ?
-                                      pmac_i2c_mode_combined :
-                                      pmac_i2c_mode_stdsub);
-                if (rc)
-                        goto bail;
-                rc = pmac_i2c_xfer(bus, addrdir, 1, command,
-                                   &data->block[1], data->block[0]);
+                buf = &data->block[1];
+                len = data->block[0];
                 break;
 
         default:
-                rc = -EINVAL;
+                return -EINVAL;
         }
+
+        rc = pmac_i2c_open(bus, 0);
+        if (rc)
+                return rc;
+
+        rc = pmac_i2c_setmode(bus, mode);
+        if (rc)
+                goto bail;
+
+        rc = pmac_i2c_xfer(bus, addrdir, subsize, subaddr, buf, len);
+        if (rc)
+                goto bail;
+
+        if (size == I2C_SMBUS_WORD_DATA && read) {
+                data->word = ((u16)local[1]) << 8;
+                data->word |= local[0];
+        }
+
  bail:
         pmac_i2c_close(bus);
         return rc;