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Date: Wed, 21 Jun 2017 17:49:43 +0300
From: Kirill Esipov <yesipov@...il.com>
To: a.zummo@...ertech.it, alexandre.belloni@...e-electrons.com
Cc: linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org,
Kirill Esipov <yesipov@...il.com>
Subject: [PATCH] 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: Kirill Esipov <yesipov@...il.com>
---
drivers/rtc/Kconfig | 9 ++++++
drivers/rtc/rtc-ds3232.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 93 insertions(+)
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 8d3b95728326..b4a6a916d4df 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -791,6 +791,15 @@ 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
+ depends on !(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
diff --git a/drivers/rtc/rtc-ds3232.c b/drivers/rtc/rtc-ds3232.c
index deff431a37c4..f94ff0685942 100644
--- a/drivers/rtc/rtc-ds3232.c
+++ b/drivers/rtc/rtc-ds3232.c
@@ -22,6 +22,8 @@
#include <linux/bcd.h>
#include <linux/slab.h>
#include <linux/regmap.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
#define DS3232_REG_SECONDS 0x00
#define DS3232_REG_MINUTES 0x01
@@ -275,6 +277,86 @@ static int ds3232_update_alarm(struct device *dev, unsigned int enabled)
return ret;
}
+/*----------------------------------------------------------------------*/
+
+#ifdef CONFIG_RTC_DRV_DS3232_HWMON
+
+/*
+ * Temperature sensor support for ds3232/ds3234 devices.
+ */
+
+#define DS3232_REG_TEMPERATURE 0x11
+
+/*
+ * 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, s32 *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 ssize_t ds3232_hwmon_show_temp(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int ret;
+ s32 temp;
+
+ ret = ds3232_hwmon_read_temp(dev, &temp);
+ if (ret < 0)
+ return ret;
+
+ return sprintf(buf, "%d\n", temp);
+}
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ds3232_hwmon_show_temp,
+ NULL, 0);
+
+static struct attribute *ds3232_hwmon_attrs[] = {
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(ds3232_hwmon);
+
+static void ds3232_hwmon_register(struct device *dev, const char *name)
+{
+ struct ds3232 *ds3232 = dev_get_drvdata(dev);
+ struct device *hwmon_dev;
+
+ hwmon_dev = devm_hwmon_device_register_with_groups(dev, name, ds3232,
+ ds3232_hwmon_groups);
+ if (IS_ERR(hwmon_dev)) {
+ dev_warn(dev, "unable to register hwmon device %ld\n",
+ PTR_ERR(hwmon_dev));
+ }
+}
+
+#else
+
+static void ds3232_hwmon_register(struct ds3232 *ds3232)
+{
+}
+
+#endif
+
static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct ds3232 *ds3232 = dev_get_drvdata(dev);
@@ -366,6 +448,8 @@ 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))
--
2.7.4
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