Commit c35c4195 authored by Kirill Esipov's avatar Kirill Esipov Committed by Alexandre Belloni
Browse files

rtc: ds3232: add temperature support



DS3232/DS3234 has the temperature registers with a resolution of 0.25
degree celsius. This enables to get the value through hwmon.

	# cat /sys/class/hwmon/hwmon0/temp1_input
	37250
Signed-off-by: default avatarKirill Esipov <yesipov@gmail.com>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent d0a67c37
......@@ -802,6 +802,14 @@ config RTC_DRV_DS3232
This driver can also be built as a module. If so, the module
will be called rtc-ds3232.
config RTC_DRV_DS3232_HWMON
bool "HWMON support for Dallas/Maxim DS3232/DS3234"
depends on RTC_DRV_DS3232 && HWMON && !(RTC_DRV_DS3232=y && HWMON=m)
default y
help
Say Y here if you want to expose temperature sensor data on
rtc-ds3232
config RTC_DRV_PCF2127
tristate "NXP PCF2127"
depends on RTC_I2C_AND_SPI
......
......@@ -22,6 +22,7 @@
#include <linux/bcd.h>
#include <linux/slab.h>
#include <linux/regmap.h>
#include <linux/hwmon.h>
#define DS3232_REG_SECONDS 0x00
#define DS3232_REG_MINUTES 0x01
......@@ -46,6 +47,8 @@
# define DS3232_REG_SR_A2F 0x02
# define DS3232_REG_SR_A1F 0x01
#define DS3232_REG_TEMPERATURE 0x11
struct ds3232 {
struct device *dev;
struct regmap *regmap;
......@@ -275,6 +278,120 @@ static int ds3232_update_alarm(struct device *dev, unsigned int enabled)
return ret;
}
/*
* Temperature sensor support for ds3232/ds3234 devices.
* A user-initiated temperature conversion is not started by this function,
* so the temperature is updated once every 64 seconds.
*/
static int ds3232_hwmon_read_temp(struct device *dev, long int *mC)
{
struct ds3232 *ds3232 = dev_get_drvdata(dev);
u8 temp_buf[2];
s16 temp;
int ret;
ret = regmap_bulk_read(ds3232->regmap, DS3232_REG_TEMPERATURE, temp_buf,
sizeof(temp_buf));
if (ret < 0)
return ret;
/*
* Temperature is represented as a 10-bit code with a resolution of
* 0.25 degree celsius and encoded in two's complement format.
*/
temp = (temp_buf[0] << 8) | temp_buf[1];
temp >>= 6;
*mC = temp * 250;
return 0;
}
static umode_t ds3232_hwmon_is_visible(const void *data,
enum hwmon_sensor_types type,
u32 attr, int channel)
{
if (type != hwmon_temp)
return 0;
switch (attr) {
case hwmon_temp_input:
return 0444;
default:
return 0;
}
}
static int ds3232_hwmon_read(struct device *dev,
enum hwmon_sensor_types type,
u32 attr, int channel, long *temp)
{
int err;
switch (attr) {
case hwmon_temp_input:
err = ds3232_hwmon_read_temp(dev, temp);
break;
default:
err = -EOPNOTSUPP;
break;
}
return err;
}
static u32 ds3232_hwmon_chip_config[] = {
HWMON_C_REGISTER_TZ,
0
};
static const struct hwmon_channel_info ds3232_hwmon_chip = {
.type = hwmon_chip,
.config = ds3232_hwmon_chip_config,
};
static u32 ds3232_hwmon_temp_config[] = {
HWMON_T_INPUT,
0
};
static const struct hwmon_channel_info ds3232_hwmon_temp = {
.type = hwmon_temp,
.config = ds3232_hwmon_temp_config,
};
static const struct hwmon_channel_info *ds3232_hwmon_info[] = {
&ds3232_hwmon_chip,
&ds3232_hwmon_temp,
NULL
};
static const struct hwmon_ops ds3232_hwmon_hwmon_ops = {
.is_visible = ds3232_hwmon_is_visible,
.read = ds3232_hwmon_read,
};
static const struct hwmon_chip_info ds3232_hwmon_chip_info = {
.ops = &ds3232_hwmon_hwmon_ops,
.info = ds3232_hwmon_info,
};
static void ds3232_hwmon_register(struct device *dev, const char *name)
{
struct ds3232 *ds3232 = dev_get_drvdata(dev);
struct device *hwmon_dev;
if (!IS_ENABLED(CONFIG_RTC_DRV_DS3232_HWMON))
return;
hwmon_dev = devm_hwmon_device_register_with_info(dev, name, ds3232,
&ds3232_hwmon_chip_info,
NULL);
if (IS_ERR(hwmon_dev)) {
dev_err(dev, "unable to register hwmon device %ld\n",
PTR_ERR(hwmon_dev));
}
}
static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct ds3232 *ds3232 = dev_get_drvdata(dev);
......@@ -366,6 +483,8 @@ static int ds3232_probe(struct device *dev, struct regmap *regmap, int irq,
if (ds3232->irq > 0)
device_init_wakeup(dev, 1);
ds3232_hwmon_register(dev, name);
ds3232->rtc = devm_rtc_device_register(dev, name, &ds3232_rtc_ops,
THIS_MODULE);
if (IS_ERR(ds3232->rtc))
......
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