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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
hwmon: (ina238) Rework and simplify temperature calculations
The temperature register is 16 bit wide for all chips. The decimal point
is at the same location (bit 7 = 1 degree C). That means we can use the
resolution to calculate temperatures. Do that to simplify the code.
There is only a single writeable temperature attribute, and it is very
unlikely that the chips supported by this driver will ever require another
one. That means checking for that attribute in the write function is
unnecessary. Drop the check. Rename the write function from
ina238_write_temp() to ina238_write_temp_max() to reflect that a single
attribute is written.
Also extend the accepted temperature value range to the range supported by
the chip registers. Limiting the accepted value range to the temperature
range supported by the chip would make it impossible to read an
out-of-range limit from the chip and to write the same value back into it.
This is undesirable, especially since the maximum temperature register does
contain the maximum register value after a chip reset, not the temperature
limit supported by the chip.
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz> # INA780
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
+24
-28
+24
-28
drivers/hwmon/ina238.c
+24
-28
drivers/hwmon/ina238.c
···
103
103
104
104
#define INA238_SHUNT_VOLTAGE_LSB 5 /* 5 uV/lsb */
105
105
#define INA238_BUS_VOLTAGE_LSB 3125 /* 3.125 mV/lsb */
106
-
#define INA238_DIE_TEMP_LSB 1250000 /* 125.0000 mC/lsb */
107
106
#define SQ52206_BUS_VOLTAGE_LSB 3750 /* 3.75 mV/lsb */
108
-
#define SQ52206_DIE_TEMP_LSB 78125 /* 7.8125 mC/lsb */
109
-
#define INA228_DIE_TEMP_LSB 78125 /* 7.8125 mC/lsb */
110
107
111
108
static const struct regmap_config ina238_regmap_config = {
112
109
.max_register = INA238_REGISTERS,
···
117
120
bool has_20bit_voltage_current; /* vshunt, vbus and current are 20-bit fields */
118
121
bool has_power_highest; /* chip detection power peak */
119
122
bool has_energy; /* chip detection energy */
120
-
u8 temp_shift; /* fixed parameters for temp calculate */
123
+
u8 temp_resolution; /* temperature register resolution in bit */
121
124
u32 power_calculate_factor; /* fixed parameters for power calculate */
122
125
u16 config_default; /* Power-on default state */
123
126
int bus_voltage_lsb; /* use for temperature calculate, uV/lsb */
124
-
int temp_lsb; /* use for temperature calculate */
125
127
};
126
128
127
129
struct ina238_data {
···
137
141
.has_20bit_voltage_current = false,
138
142
.has_energy = false,
139
143
.has_power_highest = false,
140
-
.temp_shift = 4,
141
144
.power_calculate_factor = 20,
142
145
.config_default = INA238_CONFIG_DEFAULT,
143
146
.bus_voltage_lsb = INA238_BUS_VOLTAGE_LSB,
144
-
.temp_lsb = INA238_DIE_TEMP_LSB,
147
+
.temp_resolution = 12,
145
148
},
146
149
[ina237] = {
147
150
.has_20bit_voltage_current = false,
148
151
.has_energy = false,
149
152
.has_power_highest = false,
150
-
.temp_shift = 4,
151
153
.power_calculate_factor = 20,
152
154
.config_default = INA238_CONFIG_DEFAULT,
153
155
.bus_voltage_lsb = INA238_BUS_VOLTAGE_LSB,
154
-
.temp_lsb = INA238_DIE_TEMP_LSB,
156
+
.temp_resolution = 12,
155
157
},
156
158
[sq52206] = {
157
159
.has_20bit_voltage_current = false,
158
160
.has_energy = true,
159
161
.has_power_highest = true,
160
-
.temp_shift = 0,
161
162
.power_calculate_factor = 24,
162
163
.config_default = SQ52206_CONFIG_DEFAULT,
163
164
.bus_voltage_lsb = SQ52206_BUS_VOLTAGE_LSB,
164
-
.temp_lsb = SQ52206_DIE_TEMP_LSB,
165
+
.temp_resolution = 16,
165
166
},
166
167
[ina228] = {
167
168
.has_20bit_voltage_current = true,
168
169
.has_energy = true,
169
170
.has_power_highest = false,
170
-
.temp_shift = 0,
171
171
.power_calculate_factor = 20,
172
172
.config_default = INA238_CONFIG_DEFAULT,
173
173
.bus_voltage_lsb = INA238_BUS_VOLTAGE_LSB,
174
-
.temp_lsb = INA228_DIE_TEMP_LSB,
174
+
.temp_resolution = 16,
175
175
},
176
176
};
177
177
···
514
522
return regmap_write(data->regmap, INA238_POWER_LIMIT, regval);
515
523
}
516
524
525
+
static int ina238_temp_from_reg(s16 regval, u8 resolution)
526
+
{
527
+
return ((regval >> (16 - resolution)) * 1000) >> (resolution - 9);
528
+
}
529
+
517
530
static int ina238_read_temp(struct device *dev, u32 attr, long *val)
518
531
{
519
532
struct ina238_data *data = dev_get_drvdata(dev);
···
530
533
err = regmap_read(data->regmap, INA238_DIE_TEMP, ®val);
531
534
if (err)
532
535
return err;
533
-
/* Signed, result in mC */
534
-
*val = div_s64(((s64)((s16)regval) >> data->config->temp_shift) *
535
-
(s64)data->config->temp_lsb, 10000);
536
+
*val = ina238_temp_from_reg(regval, data->config->temp_resolution);
536
537
break;
537
538
case hwmon_temp_max:
538
539
err = regmap_read(data->regmap, INA238_TEMP_LIMIT, ®val);
539
540
if (err)
540
541
return err;
541
542
/* Signed, result in mC */
542
-
*val = div_s64(((s64)((s16)regval) >> data->config->temp_shift) *
543
-
(s64)data->config->temp_lsb, 10000);
543
+
*val = ina238_temp_from_reg(regval, data->config->temp_resolution);
544
544
break;
545
545
case hwmon_temp_max_alarm:
546
546
err = regmap_read(data->regmap, INA238_DIAG_ALERT, ®val);
···
553
559
return 0;
554
560
}
555
561
556
-
static int ina238_write_temp(struct device *dev, u32 attr, long val)
562
+
static u16 ina238_temp_to_reg(long val, u8 resolution)
563
+
{
564
+
int fraction = 1000 - DIV_ROUND_CLOSEST(1000, BIT(resolution - 9));
565
+
566
+
val = clamp_val(val, -255000 - fraction, 255000 + fraction);
567
+
568
+
return (DIV_ROUND_CLOSEST(val << (resolution - 9), 1000) << (16 - resolution)) & 0xffff;
569
+
}
570
+
571
+
static int ina238_write_temp_max(struct device *dev, long val)
557
572
{
558
573
struct ina238_data *data = dev_get_drvdata(dev);
559
574
int regval;
560
575
561
-
if (attr != hwmon_temp_max)
562
-
return -EOPNOTSUPP;
563
-
564
-
/* Signed */
565
-
val = clamp_val(val, -40000, 125000);
566
-
regval = div_s64(val * 10000, data->config->temp_lsb) << data->config->temp_shift;
567
-
regval = clamp_val(regval, S16_MIN, S16_MAX) & (0xffff << data->config->temp_shift);
568
-
576
+
regval = ina238_temp_to_reg(val, data->config->temp_resolution);
569
577
return regmap_write(data->regmap, INA238_TEMP_LIMIT, regval);
570
578
}
571
579
···
624
628
err = ina238_write_power_max(dev, val);
625
629
break;
626
630
case hwmon_temp:
627
-
err = ina238_write_temp(dev, attr, val);
631
+
err = ina238_write_temp_max(dev, val);
628
632
break;
629
633
default:
630
634
err = -EOPNOTSUPP;