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hwmon: (sht3x) add medium repeatability support

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Add support for medium repeatability.

Per datasheet:

The stated repeatability is 3 times the standard deviation (3σ)
of multiple consecutive measurements at the stated repeatability
and at constant ambient conditions. It is a measure for the noise
on the physical sensor output. Different measurement modes allow
for high/medium/low repeatability.

For the humidity sensor, repeatability is documented as
0.25% RH for low repeatability, 0.15% RH for medium repeatability,
and 0.10% RH for high repeatability. Support all three modes.

Signed-off-by: JuenKit Yip <JuenKit_Yip@hotmail.com>
Link: https://lore.kernel.org/r/DB4PR10MB6261A70CD0444248ADDCC3219258A@DB4PR10MB6261.EURPRD10.PROD.OUTLOOK.COM
[groeck: Added details to description]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
JuenKit Yip 2023-06-17 00:00:15 +08:00 committed by Guenter Roeck
parent 7d6d53ba3b
commit 3d2c211c0d
1 changed files with 24 additions and 0 deletions
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24
drivers/hwmon/sht3x.c
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@ -24,6 +24,9 @@
/* commands (high repeatability mode) */
static const unsigned char sht3x_cmd_measure_single_hpm[] = { 0x24, 0x00 };
/* commands (medium repeatability mode) */
static const unsigned char sht3x_cmd_measure_single_mpm[] = { 0x24, 0x0b };
/* commands (low repeatability mode) */
static const unsigned char sht3x_cmd_measure_single_lpm[] = { 0x24, 0x16 };
@ -41,6 +44,7 @@ static const unsigned char sht3x_cmd_clear_status_reg[] = { 0x30, 0x41 };
/* delays for single-shot mode i2c commands, both in us */
#define SHT3X_SINGLE_WAIT_TIME_HPM 15000
#define SHT3X_SINGLE_WAIT_TIME_MPM 6000
#define SHT3X_SINGLE_WAIT_TIME_LPM 4000
#define SHT3X_WORD_LEN 2
@ -68,6 +72,7 @@ enum sht3x_limits {
enum sht3x_repeatability {
low_repeatability,
medium_repeatability,
high_repeatability,
};
@ -87,6 +92,20 @@ static const char periodic_measure_commands_hpm[][SHT3X_CMD_LENGTH] = {
{0x27, 0x37},
};
/* periodic measure commands (medium repeatability) */
static const char periodic_measure_commands_mpm[][SHT3X_CMD_LENGTH] = {
/* 0.5 measurements per second */
{0x20, 0x24},
/* 1 measurements per second */
{0x21, 0x26},
/* 2 measurements per second */
{0x22, 0x20},
/* 4 measurements per second */
{0x23, 0x22},
/* 10 measurements per second */
{0x27, 0x21},
};
/* periodic measure commands (low repeatability mode) */
static const char periodic_measure_commands_lpm[][SHT3X_CMD_LENGTH] = {
/* 0.5 measurements per second */
@ -444,6 +463,9 @@ static void sht3x_select_command(struct sht3x_data *data)
if (data->repeatability == high_repeatability) {
data->command = sht3x_cmd_measure_single_hpm;
data->wait_time = SHT3X_SINGLE_WAIT_TIME_HPM;
} else if (data->repeatability == medium_repeatability) {
data->command = sht3x_cmd_measure_single_mpm;
data->wait_time = SHT3X_SINGLE_WAIT_TIME_MPM;
} else {
data->command = sht3x_cmd_measure_single_lpm;
data->wait_time = SHT3X_SINGLE_WAIT_TIME_LPM;
@ -591,6 +613,8 @@ static ssize_t update_interval_store(struct device *dev,
if (mode > 0) {
if (data->repeatability == high_repeatability)
command = periodic_measure_commands_hpm[mode - 1];
else if (data->repeatability == medium_repeatability)
command = periodic_measure_commands_mpm[mode - 1];
else
command = periodic_measure_commands_lpm[mode - 1];