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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

drivers/rtc/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -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

drivers/rtc/rtc-ds3232.c

+119 −0
Original line number Diff line number Diff line
@@ -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))