hwmon: (lm75) Add detection of the National Semiconductor LM75A
Add support for detection of the National Semiconductor LM75A using the ID
register value.
Signed-off-by: Len Sorensen <lsorense@csclub.uwaterloo.ca>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/Documentation/hwmon/lm75 b/Documentation/hwmon/lm75
index 8e6356f..a179040 100644
--- a/Documentation/hwmon/lm75
+++ b/Documentation/hwmon/lm75
@@ -7,6 +7,11 @@
Addresses scanned: I2C 0x48 - 0x4f
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/
+ * National Semiconductor LM75A
+ Prefix: 'lm75a'
+ Addresses scanned: I2C 0x48 - 0x4f
+ Datasheet: Publicly available at the National Semiconductor website
+ http://www.national.com/
* Dallas Semiconductor DS75
Prefix: 'lm75'
Addresses scanned: I2C 0x48 - 0x4f
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 47621ab..19d72bc 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -521,7 +521,7 @@
- Dallas Semiconductor DS75 and DS1775
- Maxim MAX6625 and MAX6626
- Microchip MCP980x
- - National Semiconductor LM75
+ - National Semiconductor LM75, LM75A
- NXP's LM75A
- ST Microelectronics STDS75
- TelCom (now Microchip) TCN75
diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index f36eb80..638dd05 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -232,6 +232,8 @@
};
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 @@
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 @@
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.
- /* Unused addresses */
+ 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. */
+
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 @@
|| 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;
}