hwmon: (adm1275) Make sure we are reading enough data for different chips

Issue:
When PEC is enabled, binding adm1272 to the adm1275 would
fail due to PEC error. See below:
adm1275: probe of xxxx failed with error -74

Diagnosis:
Per the datasheet of adm1272, adm1278, adm1293 and amd1294,
PMON_CONFIG (0xd4) is 16bits wide. On the other hand,
PMON_CONFIG (0xd4) for adm1275 is 8bits wide. The driver should not
assume everything is 8bits wide and read only 8bits from it.

Solution:
If it is adm1272, adm1278, adm1293 and adm1294, use i2c_read_word.
Else, use i2c_read_byte

Testing:
Binding adm1272 to the driver.
The change is only tested on adm1272.

Signed-off-by: Chu Lin <linchuyuan@google.com>
Link: https://lore.kernel.org/r/20200709040612.3977094-1-linchuyuan@google.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/pmbus/adm1275.c b/drivers/hwmon/pmbus/adm1275.c
index e25f541227daef2df9fff7308fce5d02a4305d4b..19317575d1c6a781e994ce05cb19c4f8099b4119 100644 (file)
--- a/drivers/hwmon/pmbus/adm1275.c
+++ b/drivers/hwmon/pmbus/adm1275.c
@@ -465,6 +465,7 @@ MODULE_DEVICE_TABLE(i2c, adm1275_id);
 static int adm1275_probe(struct i2c_client *client,
                         const struct i2c_device_id *id)
 {
+       s32 (*config_read_fn)(const struct i2c_client *client, u8 reg);
        u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];
        int config, device_config;
        int ret;
@@ -510,11 +511,16 @@ static int adm1275_probe(struct i2c_client *client,
                           "Device mismatch: Configured %s, detected %s\n",
                           id->name, mid->name);
 
-       config = i2c_smbus_read_byte_data(client, ADM1275_PMON_CONFIG);
+       if (mid->driver_data == adm1272 || mid->driver_data == adm1278 ||
+           mid->driver_data == adm1293 || mid->driver_data == adm1294)
+               config_read_fn = i2c_smbus_read_word_data;
+       else
+               config_read_fn = i2c_smbus_read_byte_data;
+       config = config_read_fn(client, ADM1275_PMON_CONFIG);
        if (config < 0)
                return config;
 
-       device_config = i2c_smbus_read_byte_data(client, ADM1275_DEVICE_CONFIG);
+       device_config = config_read_fn(client, ADM1275_DEVICE_CONFIG);
        if (device_config < 0)
                return device_config;