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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>
This commit is contained in:
Len Sorensen 2011-03-21 17:59:36 +01:00 committed by Jean Delvare
parent 96b4b9bfea
commit 05e82fe40f
3 changed files with 47 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
Documentation/hwmon/lm75
View File

@ -7,6 +7,11 @@ Supported chips:
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

2
drivers/hwmon/Kconfig
View File

@ -521,7 +521,7 @@ config SENSORS_LM75
- 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

56
drivers/hwmon/lm75.c
View File

@ -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;
}