diff options
Diffstat (limited to 'drivers/hwmon/lm75.c')
| -rw-r--r-- | drivers/hwmon/lm75.c | 56 |
1 files changed, 41 insertions, 15 deletions
diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c index f36eb80d227f..638dd0586e3f 100644 --- a/drivers/hwmon/lm75.c +++ b/drivers/hwmon/lm75.c @@ -232,6 +232,8 @@ static const struct i2c_device_id lm75_ids[] = { }; MODULE_DEVICE_TABLE(i2c, lm75_ids); +#define LM75A_ID 0xA1 + /* Return 0 if detection is successful, -ENODEV otherwise */ static int lm75_detect(struct i2c_client *new_client, struct i2c_board_info *info) @@ -239,6 +241,7 @@ static int lm75_detect(struct i2c_client *new_client, struct i2c_adapter *adapter = new_client->adapter; int i; int cur, conf, hyst, os; + bool is_lm75a = 0; if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA)) @@ -250,23 +253,43 @@ static int lm75_detect(struct i2c_client *new_client, addresses 0x04-0x07 returning the last read value. The cycling+unused addresses combination is not tested, since it would significantly slow the detection down and would - hardly add any value. */ + hardly add any value. + + The National Semiconductor LM75A is different than earlier + LM75s. It has an ID byte of 0xaX (where X is the chip + revision, with 1 being the only revision in existence) in + register 7, and unused registers return 0xff rather than the + last read value. */ - /* Unused addresses */ cur = i2c_smbus_read_word_data(new_client, 0); conf = i2c_smbus_read_byte_data(new_client, 1); - hyst = i2c_smbus_read_word_data(new_client, 2); - if (i2c_smbus_read_word_data(new_client, 4) != hyst - || i2c_smbus_read_word_data(new_client, 5) != hyst - || i2c_smbus_read_word_data(new_client, 6) != hyst - || i2c_smbus_read_word_data(new_client, 7) != hyst) - return -ENODEV; - os = i2c_smbus_read_word_data(new_client, 3); - if (i2c_smbus_read_word_data(new_client, 4) != os - || i2c_smbus_read_word_data(new_client, 5) != os - || i2c_smbus_read_word_data(new_client, 6) != os - || i2c_smbus_read_word_data(new_client, 7) != os) - return -ENODEV; + + /* First check for LM75A */ + if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) { + /* LM75A returns 0xff on unused registers so + just to be sure we check for that too. */ + if (i2c_smbus_read_byte_data(new_client, 4) != 0xff + || i2c_smbus_read_byte_data(new_client, 5) != 0xff + || i2c_smbus_read_byte_data(new_client, 6) != 0xff) + return -ENODEV; + is_lm75a = 1; + hyst = i2c_smbus_read_word_data(new_client, 2); + os = i2c_smbus_read_word_data(new_client, 3); + } else { /* Traditional style LM75 detection */ + /* Unused addresses */ + hyst = i2c_smbus_read_word_data(new_client, 2); + if (i2c_smbus_read_word_data(new_client, 4) != hyst + || i2c_smbus_read_word_data(new_client, 5) != hyst + || i2c_smbus_read_word_data(new_client, 6) != hyst + || i2c_smbus_read_word_data(new_client, 7) != hyst) + return -ENODEV; + os = i2c_smbus_read_word_data(new_client, 3); + if (i2c_smbus_read_word_data(new_client, 4) != os + || i2c_smbus_read_word_data(new_client, 5) != os + || i2c_smbus_read_word_data(new_client, 6) != os + || i2c_smbus_read_word_data(new_client, 7) != os) + return -ENODEV; + } /* Unused bits */ if (conf & 0xe0) @@ -278,9 +301,12 @@ static int lm75_detect(struct i2c_client *new_client, || i2c_smbus_read_word_data(new_client, i + 2) != hyst || i2c_smbus_read_word_data(new_client, i + 3) != os) return -ENODEV; + if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7) + != LM75A_ID) + return -ENODEV; } - strlcpy(info->type, "lm75", I2C_NAME_SIZE); + strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE); return 0; } |