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

[Eduardo Valentin <edubezval@gmail.com>]

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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@csie.org> wrote:
> > Hi,
> >
> > On Tue, Jan 6, 2015 at 11:24 PM, Eduardo Valentin <edubezval@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@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@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?

Cheers,

> 
> >>> +     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
> >>>

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