Commit b2644494 authored by Guenter Roeck's avatar Guenter Roeck
Browse files

hwmon: (lm90) Add support for unsigned and signed temperatures 



ADT7461 and TMP451 temperature sensors support extended temperature ranges.
If standard temperature range is selected, the temperature range is
unsigned and limited to 0 .. 127 degrees C. For TMP461, the standard
temperature range is -128000 ... 127000 degrees C. Distinguish between
the two chips by introducing a feature flag indicating if the standard
temperature range is signed or unsigned. Use the same flag for MAX6646/
MAX6647 as well since those chips also support unsigned temperatures.

Note that while the datasheet for ADT7461 suggests that the default
temperature range is unsigned, tests with a real chip suggest that this
is not the case: If the temperature offset is set to a value << 0,
the temperature register does report negative values.

Tests with real chips show that MAX6680/MAX6681 and SA56004 report
temperatures of 128 degrees C and higher as negative temperatures.
Add respective comments to the code.

Also use clamp_val() and DIV_ROUND_CLOSEST where appropriate in
calculations.

Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent d70fa73d

drivers/hwmon/lm90.c

+42 −28
Original line number Diff line number Diff line
@@ -170,6 +170,7 @@ enum chips { adm1032, adt7461, adt7461a, g781, lm86, lm90, lm99, 
#define LM90_FLAG_ADT7461_EXT	BIT(0)	/* ADT7461 extended mode	*/

/* Device features */

#define LM90_HAVE_OFFSET	BIT(1)	/* temperature offset register	*/

#define LM90_HAVE_UNSIGNED_TEMP	BIT(2)	/* temperatures are unsigned	*/

#define LM90_HAVE_REM_LIMIT_EXT	BIT(3)	/* extended remote limit	*/

#define LM90_HAVE_EMERGENCY	BIT(4)	/* 3rd upper (emergency) limit	*/

#define LM90_HAVE_EMERGENCY_ALARM BIT(5)/* emergency alarm		*/
@@ -354,6 +355,11 @@ static const struct lm90_params lm90_params[] = { 
		.max_convrate = 10,

	},

	[adt7461] = {

		/*

		 * Standard temperature range is supposed to be unsigned,

		 * but that does not match reality. Negative temperatures

		 * are always reported.

		 */

		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT

		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP

		  | LM90_HAVE_CRIT | LM90_HAVE_PARTIAL_PEC,
@@ -392,7 +398,8 @@ static const struct lm90_params lm90_params[] = { 
		.max_convrate = 9,

	},

	[max6646] = {

		.flags = LM90_HAVE_CRIT | LM90_HAVE_BROKEN_ALERT,

		.flags = LM90_HAVE_CRIT | LM90_HAVE_BROKEN_ALERT

		  | LM90_HAVE_UNSIGNED_TEMP,

		.alert_alarms = 0x7c,

		.max_convrate = 6,

		.reg_local_ext = MAX6657_REG_LOCAL_TEMPL,
@@ -416,6 +423,11 @@ static const struct lm90_params lm90_params[] = { 
		.reg_local_ext = MAX6657_REG_LOCAL_TEMPL,

	},

	[max6680] = {

		/*

		 * Apparent temperatures of 128 degrees C or higher are reported

		 * and treated as negative temperatures (meaning min_alarm will

		 * be set).

		 */

		.flags = LM90_HAVE_OFFSET | LM90_HAVE_CRIT

		  | LM90_HAVE_CRIT_ALRM_SWP | LM90_HAVE_BROKEN_ALERT,

		.alert_alarms = 0x7c,
@@ -434,6 +446,11 @@ static const struct lm90_params lm90_params[] = { 
		.max_convrate = 8,

	},

	[sa56004] = {

		/*

		 * Apparent temperatures of 128 degrees C or higher are reported

		 * and treated as negative temperatures (meaning min_alarm will

		 * be set).

		 */

		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT | LM90_HAVE_CRIT,

		.alert_alarms = 0x7b,

		.max_convrate = 9,
@@ -441,7 +458,8 @@ static const struct lm90_params lm90_params[] = { 
	},

	[tmp451] = {

		.flags = LM90_HAVE_OFFSET | LM90_HAVE_REM_LIMIT_EXT

		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP | LM90_HAVE_CRIT,

		  | LM90_HAVE_BROKEN_ALERT | LM90_HAVE_EXTENDED_TEMP | LM90_HAVE_CRIT

		  | LM90_HAVE_UNSIGNED_TEMP,

		.alert_alarms = 0x7c,

		.max_convrate = 9,

		.reg_local_ext = TMP451_REG_LOCAL_TEMPL,
@@ -1118,33 +1136,27 @@ static inline int temp_from_u16_adt7461(struct lm90_data *data, u16 val) 
static u8 temp_to_u8_adt7461(struct lm90_data *data, long val)

{

	if (data->flags & LM90_FLAG_ADT7461_EXT) {

		if (val <= -64000)

			return 0;

		if (val >= 191000)

			return 0xFF;

		return (val + 500 + 64000) / 1000;

		val = clamp_val(val, -64000, 191000);

		val += 64000;

	} else if (data->flags & LM90_HAVE_UNSIGNED_TEMP) {

		val = clamp_val(val, 0, 127000);

	} else {

		val = clamp_val(val, -128000, 127000);

	}

	if (val <= 0)

		return 0;

	if (val >= 127000)

		return 127;

	return (val + 500) / 1000;

	return DIV_ROUND_CLOSEST(val, 1000);

}



static u16 temp_to_u16_adt7461(struct lm90_data *data, long val)

{

	if (data->flags & LM90_FLAG_ADT7461_EXT) {

		if (val <= -64000)

			return 0;

		if (val >= 191750)

			return 0xFFC0;

		return (val + 64000 + 125) / 250 * 64;

		val = clamp_val(val, -64000, 191000);

		val += 64000;

	} else if (data->flags & LM90_HAVE_UNSIGNED_TEMP) {

		val = clamp_val(val, 0, 127000);

	} else {

		val = clamp_val(val, -128000, 127000);

	}

	if (val <= 0)

		return 0;

	if (val >= 127750)

		return 0x7FC0;

	return (val + 125) / 250 * 64;

	return DIV_ROUND_CLOSEST(val, 1000) & 0xfff0;

}



/* pec used for devices with PEC support */
@@ -1190,7 +1202,7 @@ static int lm90_get_temp11(struct lm90_data *data, int index) 


	if (data->flags & LM90_HAVE_EXTENDED_TEMP)

		temp = temp_from_u16_adt7461(data, temp11);

	else if (data->kind == max6646)

	else if (data->flags & LM90_HAVE_UNSIGNED_TEMP)

		temp = temp_from_u16(temp11);

	else

		temp = temp_from_s16(temp11);
@@ -1227,7 +1239,7 @@ static int lm90_set_temp11(struct lm90_data *data, int index, long val) 


	if (data->flags & LM90_HAVE_EXTENDED_TEMP)

		data->temp11[index] = temp_to_u16_adt7461(data, val);

	else if (data->kind == max6646)

	else if (data->flags & LM90_HAVE_UNSIGNED_TEMP)

		data->temp11[index] = temp_to_u8(val) << 8;

	else if (data->flags & LM90_HAVE_REM_LIMIT_EXT)

		data->temp11[index] = temp_to_s16(val);
@@ -1253,7 +1265,7 @@ static int lm90_get_temp8(struct lm90_data *data, int index) 


	if (data->flags & LM90_HAVE_EXTENDED_TEMP)

		temp = temp_from_u8_adt7461(data, temp8);

	else if (data->kind == max6646)

	else if (data->flags & LM90_HAVE_UNSIGNED_TEMP)

		temp = temp_from_u8(temp8);

	else

		temp = temp_from_s8(temp8);
@@ -1289,7 +1301,7 @@ static int lm90_set_temp8(struct lm90_data *data, int index, long val) 


	if (data->flags & LM90_HAVE_EXTENDED_TEMP)

		data->temp8[index] = temp_to_u8_adt7461(data, val);

	else if (data->kind == max6646)

	else if (data->flags & LM90_HAVE_UNSIGNED_TEMP)

		data->temp8[index] = temp_to_u8(val);

	else

		data->temp8[index] = temp_to_s8(val);
@@ -1307,7 +1319,7 @@ static int lm90_get_temphyst(struct lm90_data *data, int index) 


	if (data->flags & LM90_HAVE_EXTENDED_TEMP)

		temp = temp_from_u8_adt7461(data, data->temp8[index]);

	else if (data->kind == max6646)

	else if (data->flags & LM90_HAVE_UNSIGNED_TEMP)

		temp = temp_from_u8(data->temp8[index]);

	else

		temp = temp_from_s8(data->temp8[index]);
@@ -1326,7 +1338,7 @@ static int lm90_set_temphyst(struct lm90_data *data, long val) 


	if (data->flags & LM90_HAVE_EXTENDED_TEMP)

		temp = temp_from_u8_adt7461(data, data->temp8[LOCAL_CRIT]);

	else if (data->kind == max6646)

	else if (data->flags & LM90_HAVE_UNSIGNED_TEMP)

		temp = temp_from_u8(data->temp8[LOCAL_CRIT]);

	else

		temp = temp_from_s8(data->temp8[LOCAL_CRIT]);
@@ -1901,6 +1913,8 @@ static int lm90_init_client(struct i2c_client *client, struct lm90_data *data) 
	 * Put MAX6680/MAX8881 into extended resolution (bit 0x10,

	 * 0.125 degree resolution) and range (0x08, extend range

	 * to -64 degree) mode for the remote temperature sensor.

	 * Note that expeciments with an actual chip do not show a difference

	 * if bit 3 is set or not.

	 */

	if (data->kind == max6680)

		config |= 0x18;