Skip to content

Commit

Permalink
hwmon: (lm90) Add support for unsigned and signed temperatures
Browse files Browse the repository at this point in the history 
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: Guenter Roeck <linux@roeck-us.net>
  • Loading branch information
Guenter Roeck committed Jul 13, 2022
1 parent d70fa73 commit b264449
Showing 1 changed file with 42 additions and 28 deletions.
70 changes: 42 additions & 28 deletions drivers/hwmon/lm90.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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,
Expand All @@ -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,
Expand All @@ -434,14 +446,20 @@ 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,
.reg_local_ext = SA56004_REG_LOCAL_TEMPL,
},
[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,
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand All @@ -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);
Expand Down Expand Up @@ -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);
Expand All @@ -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]);
Expand All @@ -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]);
Expand Down Expand Up @@ -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;
Expand Down

0 comments on commit b264449

Please sign in to comment.