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

On Sat, Jan 10, 2015 at 2:07 AM, Eduardo Valentin [off-list ref] wrote:

On Thu, Jan 08, 2015 at 09:33:54PM +0800, Chen-Yu Tsai wrote:

quoted

On Thu, Jan 8, 2015 at 12:24 AM, Chen-Yu Tsai [off-list ref] wrote:

quoted

Hi,

On Tue, Jan 6, 2015 at 11:24 PM, Eduardo Valentin [off-list ref] wrote:

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Hello Chen-Yu,


On Tue, Jan 06, 2015 at 10:35:13AM +0800, Chen-Yu Tsai wrote:

quoted

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 <redacted>
---
 .../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.

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 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.

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+     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

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                        return error;
                }
                ...

quoted

@@ -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