[PATCH 03/17] Input: sun4i-ts: Add thermal zone sensor support

[Chen-Yu Tsai]

On Sat, Jan 10, 2015 at 2:07 AM, Eduardo Valentin <edubezval at gmail.com> wrote:
> On Thu, Jan 08, 2015 at 09:33:54PM +0800, Chen-Yu Tsai wrote:
>> On Thu, Jan 8, 2015 at 12:24 AM, Chen-Yu Tsai <wens at csie.org> wrote:
>> > Hi,
>> >
>> > On Tue, Jan 6, 2015 at 11:24 PM, Eduardo Valentin <edubezval at gmail.com> wrote:
>> >> Hello Chen-Yu,
>> >>
>> >>
>> >> On Tue, Jan 06, 2015 at 10:35:13AM +0800, Chen-Yu Tsai wrote:
>> >>> The touchscreen controller has a temperature sensor embedded in the SoC,
>> >>> which already has hwmon support in the driver.
>> >>>
>> >>> Add DT thermal zone support so we can use it with cpufreq for thermal
>> >>> throttling.
>> >>>
>> >>> Signed-off-by: Chen-Yu Tsai <wens at csie.org>
>> >>> ---
>> >>>  .../bindings/input/touchscreen/sun4i.txt           |  1 +
>> >>>  drivers/input/touchscreen/sun4i-ts.c               | 27 ++++++++++++++++++++++
>> >>>  2 files changed, 28 insertions(+)
>> >>>
>> >>> diff --git a/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt b/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt
>> >>> index aef57791f40b..7f1110adbd24 100644
>> >>> --- a/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt
>> >>> +++ b/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt
>> >>> @@ -5,6 +5,7 @@ Required properties:
>> >>>   - compatible: "allwinner,sun4i-a10-ts"
>> >>>   - reg: mmio address range of the chip
>> >>>   - interrupts: interrupt to which the chip is connected
>> >>> + - #thermal-sensor-cells: shall be 0
>> >>>
>> >>
>> >> You may want to update your Example section too, below.
>> >> Example:
>> >>
>> >>         rtp: rtp at 01c25000 {
>> >>                 compatible = "allwinner,sun4i-a10-ts";
>> >>                 reg = <0x01c25000 0x100>;
>> >>                 interrupts = <29>;
>> >>                 allwinner,ts-attached;
>> >>                 #thermal-sensor-cells = <0>;
>> >>         };
>> >
>> > Ok.
>> >
>> >>
>> >>
>> >>>  Optional properties:
>> >>>   - allwinner,ts-attached: boolean indicating that an actual touchscreen is
>> >>> diff --git a/drivers/input/touchscreen/sun4i-ts.c b/drivers/input/touchscreen/sun4i-ts.c
>> >>> index 28a06749ae42..b6e9043446d6 100644
>> >>> --- a/drivers/input/touchscreen/sun4i-ts.c
>> >>> +++ b/drivers/input/touchscreen/sun4i-ts.c
>> >>> @@ -34,6 +34,7 @@
>> >>>
>> >>>  #include <linux/err.h>
>> >>>  #include <linux/hwmon.h>
>> >>> +#include <linux/thermal.h>
>> >>>  #include <linux/init.h>
>> >>>  #include <linux/input.h>
>> >>>  #include <linux/interrupt.h>
>> >>> @@ -107,6 +108,7 @@
>> >>>  struct sun4i_ts_data {
>> >>>       struct device *dev;
>> >>>       struct input_dev *input;
>> >>> +     struct thermal_zone_device *tz;
>> >>>       void __iomem *base;
>> >>>       unsigned int irq;
>> >>>       bool ignore_fifo_data;
>> >>> @@ -180,6 +182,23 @@ static void sun4i_ts_close(struct input_dev *dev)
>> >>>       writel(TEMP_IRQ_EN(1), ts->base + TP_INT_FIFOC);
>> >>>  }
>> >>>
>> >>> +static int get_temp(void *data, long *temp)
>> >>> +{
>> >>> +     struct sun4i_ts_data *ts = data;
>> >>> +
>> >>> +     /* No temp_data until the first irq */
>> >>> +     if (ts->temp_data == -1)
>> >>> +             return -EAGAIN;
>> >>> +
>> >>> +     *temp = (ts->temp_data - 1447) * 100;
>> >>> +
>> >>
>> >> Care to explain the formula in a simple comment?
>> >
>> > This was just copied from the hwmon section. AFAIK there is no documentation
>> > for the formula. It was probably copied from Allwinner's SDK code.
>> >
>> > Hans? Do you remember where you got this?
>>
>> So this is from the AXP209 datasheet. The Allwinner SoC datasheets don't
>> mention the formula to calculate the temperature. But since Allwinner
>> and X-powers are affiliated, it's possible they use the same formula.
>>
>> http://comments.gmane.org/gmane.comp.hardware.netbook.arm.sunxi/3838
>
> Ok. We use in the thermal framework  miliCelsius as the temperature
> unit. Can you make sure the resulting temperature is in miliCelsius?

Yes the result is in miliCelsius.

>>
>> >>> +     return 0;
>> >>> +}
>> >>> +
>> >>> +static struct thermal_zone_of_device_ops sun4i_ts_tz_ops = {
>> >>> +     .get_temp = get_temp,
>> >>> +};
>> >>> +
>> >>>  static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
>> >>>                        char *buf)
>> >>>  {
>> >>> @@ -288,6 +307,11 @@ static int sun4i_ts_probe(struct platform_device *pdev)
>> >>>       if (IS_ERR(hwmon))
>> >>>               return PTR_ERR(hwmon);
>> >>>
>> >>> +     ts->tz = thermal_zone_of_sensor_register(ts->dev, 0, ts,
>> >>> +                                              &sun4i_ts_tz_ops);
>> >>> +     if (IS_ERR(ts->tz))
>> >>> +             ts->tz = NULL;
>> >>> +
>> >>>       writel(TEMP_IRQ_EN(1), ts->base + TP_INT_FIFOC);
>> >>>
>> >>>       if (ts_attached) {
>> >>
>> >> here.. if input_register_device fails, you will keep an orphan thermal zone
>> >> registered in your system:
>> >>
>> >>                 error = input_register_device(ts->input);
>> >>                 if (error) {
>> >>                         writel(0, ts->base + TP_INT_FIFOC);
>> >
>> > Will add an unregister call here.
>> >
>> >
>> > Thanks for the review.
>> >
>> > ChenYu
>> >
>> >>                         return error;
>> >>                 }
>> >>                 ...
>> >>
>> >>
>> >>> @@ -310,6 +334,9 @@ static int sun4i_ts_remove(struct platform_device *pdev)
>> >>>       if (ts->input)
>> >>>               input_unregister_device(ts->input);
>> >>>
>> >>> +     if (ts->tz)
>> >>> +             thermal_zone_of_sensor_unregister(ts->dev, ts->tz);
>> >>> +
>> >>>       /* Deactivate all IRQs */
>> >>>       writel(0, ts->base + TP_INT_FIFOC);
>> >>>
>> >>> --
>> >>> 2.1.4
>> >>>