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path: root/drivers/hwmon/lm75.c
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Diffstat (limited to 'drivers/hwmon/lm75.c')
-rw-r--r--drivers/hwmon/lm75.c66
1 files changed, 45 insertions, 21 deletions
diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index f36eb80d227..ef902d5d06a 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -232,13 +232,16 @@ 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)
{
struct i2c_adapter *adapter = new_client->adapter;
int i;
- int cur, conf, hyst, os;
+ int conf, hyst, os;
+ bool is_lm75a = 0;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_WORD_DATA))
@@ -250,37 +253,58 @@ 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.
- /* 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;
+ 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 bits */
+ conf = i2c_smbus_read_byte_data(new_client, 1);
if (conf & 0xe0)
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_byte_data(new_client, 2);
+ os = i2c_smbus_read_byte_data(new_client, 3);
+ } else { /* Traditional style LM75 detection */
+ /* Unused addresses */
+ hyst = i2c_smbus_read_byte_data(new_client, 2);
+ if (i2c_smbus_read_byte_data(new_client, 4) != hyst
+ || i2c_smbus_read_byte_data(new_client, 5) != hyst
+ || i2c_smbus_read_byte_data(new_client, 6) != hyst
+ || i2c_smbus_read_byte_data(new_client, 7) != hyst)
+ return -ENODEV;
+ os = i2c_smbus_read_byte_data(new_client, 3);
+ if (i2c_smbus_read_byte_data(new_client, 4) != os
+ || i2c_smbus_read_byte_data(new_client, 5) != os
+ || i2c_smbus_read_byte_data(new_client, 6) != os
+ || i2c_smbus_read_byte_data(new_client, 7) != os)
+ return -ENODEV;
+ }
+
/* Addresses cycling */
- for (i = 8; i < 0xff; i += 8) {
+ for (i = 8; i <= 248; i += 40) {
if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
- || i2c_smbus_read_word_data(new_client, i + 2) != hyst
- || i2c_smbus_read_word_data(new_client, i + 3) != os)
+ || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
+ || i2c_smbus_read_byte_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;
}