2017-06-22 1:24 GMT+03:00 Guenter Roeck [off-list ref]:

On Wed, Jun 21, 2017 at 05:49:43PM +0300, Kirill Esipov wrote:

quoted

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 <redacted>
---
 drivers/rtc/Kconfig      |  9 ++++++
 drivers/rtc/rtc-ds3232.c | 84 ++++++++++++++++++++++++++++++

++++++++++++++++++

quoted

 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)

quoted

      return ret;
 }

+/*---------------------------------------------------------

-------------*/

quoted

+
+#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,

quoted

+ * 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,

quoted

+                             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,

quoted

+

ds3232_hwmon_groups);

Any reason for not using devm_hwmon_device_register_with_info() ?

Just to keep uniformity,  because other rtc drivers with hwmon (rtc-ds1307,
rtc-rv3029c2) use
devm_hwmon_device_register_with_groups().

Guenter

quoted

+     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)

quoted

 {
      struct ds3232 *ds3232 = dev_get_drvdata(dev);

@@ -366,6 +448,8 @@ static int ds3232_probe(struct device *dev, struct

regmap *regmap, int irq,

quoted

      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))

-- 
Kirill Esipov