Re: rtc: ds3232: add temperature support

[Guenter Roeck]

On 06/22/2017 05:07 AM, Kirill Esipov wrote:
> 2017-06-22 1:24 GMT+03:00 Guenter Roeck <linux@xxxxxxxxxxxx <mailto:linux@xxxxxxxxxxxx>>:
>
>     On Wed, Jun 21, 2017 at 05:49:43PM +0300, Kirill Esipov wrote:
>      > 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@xxxxxxxxx <mailto:yesipov@xxxxxxxxx>>
>      > ---
>      >  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);
>
>     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().

Hmm. Odd reason. With this line of argument, a new API should never be used because
"everyone else uses the old API". How about converting the other drivers to use
new API instead ?

The idea behind the new API was to simplify drivers and make them independent
of the sysfs ABI. That doesn't mean that drivers _have_ to use that API, though,
so feel free to stick with the above.

Guenter

>     Guenter
>
>      > +     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))
>
>
>
>
> --
> Kirill Esipov