Re: [PATCH v2] thermal: add temperature sensor support for tango SoC

[Eduardo Valentin <edubezval@gmail.com>]

Hello Marc,

First of all, thanks for keeping this driver simple.

A couple of extra documentation needed to add the driver. Please see
comments as follows.

On Fri, Mar 04, 2016 at 04:52:47PM +0100, Mason wrote:
> From: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
> 
> There are three temperature sensors in SMP8758.
> 
> Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
> ---
>  drivers/thermal/Kconfig         |   6 +++
>  drivers/thermal/Makefile        |   1 +
>  drivers/thermal/tango_thermal.c | 113 ++++++++++++++++++++++++++++++++++++++++

Can you please add a device tree binding entry under

Documentation/devicetree/bindings/thermal/ 
?


>  3 files changed, 120 insertions(+)
>  create mode 100644 drivers/thermal/tango_thermal.c
> 
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 7c92c09be213..b63298276532 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -254,6 +254,12 @@ config ARMADA_THERMAL
>  	  Enable this option if you want to have support for thermal management
>  	  controller present in Armada 370 and Armada XP SoC.
>  
> +config TANGO_THERMAL
> +	tristate "Tango4 thermal management"
> +	depends on ARCH_TANGO || COMPILE_TEST
> +	help
> +	  Enable SMP8758 temperature sensor driver.

checkpatch.pl --strict complains about this, could you please improve
the description of your drivers help entry?

> +
>  config TEGRA_SOCTHERM
>  	tristate "Tegra SOCTHERM thermal management"
>  	depends on ARCH_TEGRA
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index cfae6a654793..8bfea2b7e722 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -35,6 +35,7 @@ obj-y				+= samsung/
>  obj-$(CONFIG_DOVE_THERMAL)  	+= dove_thermal.o
>  obj-$(CONFIG_DB8500_THERMAL)	+= db8500_thermal.o
>  obj-$(CONFIG_ARMADA_THERMAL)	+= armada_thermal.o
> +obj-$(CONFIG_TANGO_THERMAL)	+= tango_thermal.o
>  obj-$(CONFIG_IMX_THERMAL)	+= imx_thermal.o
>  obj-$(CONFIG_DB8500_CPUFREQ_COOLING)	+= db8500_cpufreq_cooling.o
>  obj-$(CONFIG_INTEL_POWERCLAMP)	+= intel_powerclamp.o
> diff --git a/drivers/thermal/tango_thermal.c b/drivers/thermal/tango_thermal.c
> new file mode 100644
> index 000000000000..eeccb6b0894e
> --- /dev/null
> +++ b/drivers/thermal/tango_thermal.c
> @@ -0,0 +1,113 @@
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/thermal.h>
> +#include <linux/platform_device.h>
> +
> +#define TEMPSI_CMD	0
> +#define TEMPSI_RES	4
> +#define TEMPSI_CFG	8
> +
> +#define CMD_OFF		0
> +#define CMD_ON		1
> +#define CMD_READ	2
> +
> +#define INDEX_OFFSET	18
> +
> +#define sensor_idle(x)		(readl_relaxed(x + TEMPSI_CMD) & BIT(7))
> +#define temp_above_thresh(x)	(readl_relaxed(x + TEMPSI_RES))
> +
> +static const u8 temperature[] = {
> +	 37,  41,  46,  51,  55,  60,  64,  69,
> +	 74,  79,  83,  88,  93,  97, 101, 106,
> +	110, 115, 120, 124, 129, 133, 137, 142,
> +};
> +
> +static int tango_get_temp(void *arg, int *res)
> +{
> +	int i;
> +	void __iomem *base = arg;
> +
> +	for (i = INDEX_OFFSET; i < 41; ++i)
> +	{

Please follow kernel coding style.


Also, can you please add a comment on the logic here? Where the 41
constant came from?

> +		writel_relaxed(i << 8 | CMD_READ, base + TEMPSI_CMD);
> +
> +		while (!sensor_idle(base))
> +			cpu_relax();
> +
> +		if (!temp_above_thresh(base))
> +			break;
> +	}
> +
> +	writel_relaxed(INDEX_OFFSET << 8 | CMD_READ, base + TEMPSI_CMD);
> +	*res = temperature[i - INDEX_OFFSET] * 1000;
> +	return 0;
> +}
> +
> +static const struct thermal_zone_of_device_ops ops = {
> +	.get_temp	= tango_get_temp,
> +};
> +
> +struct tango_thermal_priv {
> +	struct thermal_zone_device *zone;
> +	void __iomem *base;
> +};
> +
> +static int tango_thermal_probe(struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	struct tango_thermal_priv *priv;
> +	struct device *dev = &pdev->dev;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	priv->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(priv->base))
> +		return PTR_ERR(priv->base);
> +
> +	writel_relaxed(CMD_ON, priv->base + TEMPSI_CMD);
> +	writel_relaxed(    50, priv->base + TEMPSI_CFG);
> +
> +	priv->zone = thermal_zone_of_sensor_register(dev, 0, priv->base, &ops);

Why registering only for id 0 when you mentioned this device has three
sensors?

> +	if (IS_ERR(priv->zone))
> +		return PTR_ERR(priv->zone);
> +
> +	platform_set_drvdata(pdev, priv);
> +	return 0;
> +}
> +
> +static int tango_thermal_remove(struct platform_device *pdev)
> +{
> +	struct tango_thermal_priv *priv = platform_get_drvdata(pdev);
> +
> +	thermal_zone_of_sensor_unregister(&pdev->dev, priv->zone);
> +
> +	writel_relaxed(      0, priv->base + TEMPSI_CFG);
> +	writel_relaxed(CMD_OFF, priv->base + TEMPSI_CMD);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id tango_sensor_ids[] = {
> +	{
> +		.compatible = "sigma,smp8758-sensor",
> +	},
> +	{ /* sentinel */ }
> +};
> +
> +static struct platform_driver tango_thermal_driver = {
> +	.probe	= tango_thermal_probe,
> +	.remove	= tango_thermal_remove,
> +	.driver	= {
> +		.name		= "tango-thermal",
> +		.of_match_table	= tango_sensor_ids,
> +	},
> +};
> +
> +module_platform_driver(tango_thermal_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Sigma Designs");
> +MODULE_DESCRIPTION("Tango temperature sensor");
> -- 
> 2.7.0