hwmon: (adt7475) Improve device detection

Check the value of register 0x3f as part of the device detection, to
make it more robust.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Jordan Crouse <jordan@cosmicpenguin.net>
Cc: "Darrick J. Wong" <djwong@us.ibm.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 20bab51e16f4..520773b16544 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -47,6 +47,7 @@
 
 #define REG_DEVID               0x3D
 #define REG_VENDID              0x3E
+#define REG_DEVID2              0x3F
 
 #define REG_STATUS1             0x41
 #define REG_STATUS2             0x42
@@ -1014,18 +1015,22 @@ static int adt7475_detect(struct i2c_client *client, int kind,
                           struct i2c_board_info *info)
 {
         struct i2c_adapter *adapter = client->adapter;
-        int vendid, devid;
+        int vendid, devid, devid2;
         const char *name;
 
         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
                 return -ENODEV;
 
         vendid = adt7475_read(REG_VENDID);
-        devid = adt7475_read(REG_DEVID);
+        devid2 = adt7475_read(REG_DEVID2);
+        if (vendid != 0x41 ||           /* Analog Devices */
+            (devid2 & 0xf8) != 0x68)
+                return -ENODEV;
 
-        if (vendid == 0x41 && devid == 0x73)
+        devid = adt7475_read(REG_DEVID);
+        if (devid == 0x73)
                 name = "adt7473";
-        else if (vendid == 0x41 && devid == 0x75 && client->addr == 0x2e)
+        else if (devid == 0x75 && client->addr == 0x2e)
                 name = "adt7475";
         else {
                 dev_dbg(&adapter->dev,