1 files changed, 50 insertions, 8 deletions

diff --git a/drivers/hwmon/adm1021.c b/drivers/hwmon/adm1021.c
index 7e76922a4ba9..f920619cd6da 100644
--- a/drivers/hwmon/adm1021.c
+++ b/drivers/hwmon/adm1021.c
@@ -331,26 +331,68 @@ static int adm1021_detect(struct i2c_client *client,
         man_id = i2c_smbus_read_byte_data(client, ADM1021_REG_MAN_ID);
         dev_id = i2c_smbus_read_byte_data(client, ADM1021_REG_DEV_ID);
 
+        if (man_id < 0 || dev_id < 0)
+                return -ENODEV;
+
         if (man_id == 0x4d && dev_id == 0x01)
                 type_name = "max1617a";
         else if (man_id == 0x41) {
                 if ((dev_id & 0xF0) == 0x30)
                         type_name = "adm1023";
-                else
+                else if ((dev_id & 0xF0) == 0x00)
                         type_name = "adm1021";
+                else
+                        return -ENODEV;
         } else if (man_id == 0x49)
                 type_name = "thmc10";
         else if (man_id == 0x23)
                 type_name = "gl523sm";
         else if (man_id == 0x54)
                 type_name = "mc1066";
-        /* LM84 Mfr ID in a different place, and it has more unused bits */
-        else if (conv_rate == 0x00
-                 && (config & 0x7F) == 0x00
-                 && (status & 0xAB) == 0x00)
-                type_name = "lm84";
-        else
-                type_name = "max1617";
+        else {
+                int lte, rte, lhi, rhi, llo, rlo;
+
+                /* extra checks for LM84 and MAX1617 to avoid misdetections */
+
+                llo = i2c_smbus_read_byte_data(client, ADM1021_REG_THYST_R(0));
+                rlo = i2c_smbus_read_byte_data(client, ADM1021_REG_THYST_R(1));
+
+                /* fail if any of the additional register reads failed */
+                if (llo < 0 || rlo < 0)
+                        return -ENODEV;
+
+                lte = i2c_smbus_read_byte_data(client, ADM1021_REG_TEMP(0));
+                rte = i2c_smbus_read_byte_data(client, ADM1021_REG_TEMP(1));
+                lhi = i2c_smbus_read_byte_data(client, ADM1021_REG_TOS_R(0));
+                rhi = i2c_smbus_read_byte_data(client, ADM1021_REG_TOS_R(1));
+
+                /*
+                 * Fail for negative temperatures and negative high limits.
+                 * This check also catches read errors on the tested registers.
+                 */
+                if ((s8)lte < 0 || (s8)rte < 0 || (s8)lhi < 0 || (s8)rhi < 0)
+                        return -ENODEV;
+
+                /* fail if all registers hold the same value */
+                if (lte == rte && lte == lhi && lte == rhi && lte == llo
+                    && lte == rlo)
+                        return -ENODEV;
+
+                /*
+                 * LM84 Mfr ID is in a different place,
+                 * and it has more unused bits.
+                 */
+                if (conv_rate == 0x00
+                    && (config & 0x7F) == 0x00
+                    && (status & 0xAB) == 0x00) {
+                        type_name = "lm84";
+                } else {
+                        /* fail if low limits are larger than high limits */
+                        if ((s8)llo > lhi || (s8)rlo > rhi)
+                                return -ENODEV;
+                        type_name = "max1617";
+                }
+        }
 
         pr_debug("Detected chip %s at adapter %d, address 0x%02x.\n",
                  type_name, i2c_adapter_id(adapter), client->addr);