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

From: [email-masked] (Eduardo Valentin)
Date: Tue, 6 Jan 2015 11:24:28 -0400

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 <[email-masked]>
> ---
>  .../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>;
	};

>  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?

> +	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);
			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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