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Date: Thu, 22 Jun 2017 06:44:09 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Kirill Esipov <yesipov@...il.com>
Cc: Alessandro Zummo <a.zummo@...ertech.it>,
alexandre.belloni@...e-electrons.com, linux-rtc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: rtc: ds3232: add temperature support
On 06/22/2017 05:07 AM, Kirill Esipov wrote:
>
>
> 2017-06-22 1:24 GMT+03:00 Guenter Roeck <linux@...ck-us.net <mailto:linux@...ck-us.net>>:
>
> 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@...il.com <mailto: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);
>
> 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
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