Re: rtc: ds3232: add temperature support

From: Kirill Esipov
Date: Thu Jun 22 2017 - 12:17:29 EST

2017-06-22 16:44 GMT+03:00 Guenter Roeck <linux@xxxxxxxxxxxx>:
> 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".

Well, I had task to add temperature feature to my device, and the
cheapest (easiest)
way was to make it as in same device drivers. I did it and decided to share.

> How about converting the other drivers to use new API instead ?

Ok, at first I'll try to use new hwmon API for current driver (rtc-ds3232) .


> 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
>
>



--
Kirill Esipov