hwmon: (w83795) Refactor bank selection

Move the bank selection code to a separate function, to avoid
duplicating it in read and write functions. Improve error reporting
on register access error.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 50 insertions, 43 deletions

diff --git a/drivers/hwmon/w83795.c b/drivers/hwmon/w83795.c
index d7e1d3693a20..c7f6b1fd0899 100644
--- a/drivers/hwmon/w83795.c
+++ b/drivers/hwmon/w83795.c
@@ -360,60 +360,67 @@ struct w83795_data {
 
 /*
  * Hardware access
+ * We assume that nobdody can change the bank outside the driver.
  */
 
-/* Ignore the possibility that somebody change bank outside the driver
- * Must be called with data->update_lock held, except during initialization */
-static u8 w83795_read(struct i2c_client *client, u16 reg)
+/* Must be called with data->update_lock held, except during initialization */
+static int w83795_set_bank(struct i2c_client *client, u8 bank)
 {
         struct w83795_data *data = i2c_get_clientdata(client);
-        u8 res = 0xff;
-        u8 new_bank = reg >> 8;
-
-        new_bank |= data->bank & 0xfc;
-        if (data->bank != new_bank) {
-                if (i2c_smbus_write_byte_data
-                    (client, W83795_REG_BANKSEL, new_bank) >= 0)
-                        data->bank = new_bank;
-                else {
-                        dev_err(&client->dev,
-                                "set bank to %d failed, fall back "
-                                "to bank %d, read reg 0x%x error\n",
-                                new_bank, data->bank, reg);
-                        res = 0x0;      /* read 0x0 from the chip */
-                        goto END;
-                }
+        int err;
+
+        /* If the same bank is already set, nothing to do */
+        if ((data->bank & 0x07) == bank)
+                return 0;
+
+        /* Change to new bank, preserve all other bits */
+        bank |= data->bank & ~0x07;
+        err = i2c_smbus_write_byte_data(client, W83795_REG_BANKSEL, bank);
+        if (err < 0) {
+                dev_err(&client->dev,
+                        "Failed to set bank to %d, err %d\n",
+                        (int)bank, err);
+                return err;
         }
-        res = i2c_smbus_read_byte_data(client, reg & 0xff);
-END:
-        return res;
+        data->bank = bank;
+
+        return 0;
 }
 
 /* Must be called with data->update_lock held, except during initialization */
-static int w83795_write(struct i2c_client *client, u16 reg, u8 value)
+static u8 w83795_read(struct i2c_client *client, u16 reg)
 {
-        struct w83795_data *data = i2c_get_clientdata(client);
-        int res;
-        u8 new_bank = reg >> 8;
-
-        new_bank |= data->bank & 0xfc;
-        if (data->bank != new_bank) {
-                res = i2c_smbus_write_byte_data(client, W83795_REG_BANKSEL,
-                                                new_bank);
-                if (res >= 0)
-                        data->bank = new_bank;
-                else {
-                        dev_err(&client->dev,
-                                "set bank to %d failed, fall back "
-                                "to bank %d, write reg 0x%x error\n",
-                                new_bank, data->bank, reg);
-                        goto END;
-                }
+        int err;
+
+        err = w83795_set_bank(client, reg >> 8);
+        if (err < 0)
+                return 0x00;    /* Arbitrary */
+
+        err = i2c_smbus_read_byte_data(client, reg & 0xff);
+        if (err < 0) {
+                dev_err(&client->dev,
+                        "Failed to read from register 0x%03x, err %d\n",
+                        (int)reg, err);
+                return 0x00;    /* Arbitrary */
         }
+        return err;
+}
 
-        res = i2c_smbus_write_byte_data(client, reg & 0xff, value);
-END:
-        return res;
+/* Must be called with data->update_lock held, except during initialization */
+static int w83795_write(struct i2c_client *client, u16 reg, u8 value)
+{
+        int err;
+
+        err = w83795_set_bank(client, reg >> 8);
+        if (err < 0)
+                return err;
+
+        err = i2c_smbus_write_byte_data(client, reg & 0xff, value);
+        if (err < 0)
+                dev_err(&client->dev,
+                        "Failed to write to register 0x%03x, err %d\n",
+                        (int)reg, err);
+        return err;
 }
 
 static struct w83795_data *w83795_update_device(struct device *dev)