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Commit 05e82fe4 authored by Len Sorensen's avatar Len Sorensen Committed by Jean Delvare
Browse files

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: default avatarLen Sorensen <lsorense@csclub.uwaterloo.ca>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 96b4b9bf

Documentation/hwmon/lm75

+5 −0
Original line number Diff line number Diff line
@@ -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

drivers/hwmon/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -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

drivers/hwmon/lm75.c

+41 −15
Original line number Diff line number Diff line
@@ -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))
@@ -250,11 +253,30 @@ 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);



	/* 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
@@ -267,6 +289,7 @@ static int lm75_detect(struct i2c_client *new_client, 
		 || 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;

}