Date:   Thu, 31 Aug 2017 23:17:49 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Tao Wang <kevin.wangtao@...ilicon.com>, rui.zhang@...el.com,
        edubezval@...il.com, robh+dt@...nel.org, mark.rutland@....com,
        xuwei5@...ilicon.com, catalin.marinas@....com, will.deacon@....com
Cc:     leo.yan@...aro.org, kevin.wangtao@...aro.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        sunzhaosheng@...ilicon.com, gengyanping@...ilicon.com
Subject: Re: [PATCH v4 2/3] thermal: hisilicon: add thermal sensor driver for
 Hi3660


Hi Kevin,


On 29/08/2017 10:17, Tao Wang wrote:
> From: Tao Wang <kevin.wangtao@...aro.org>
> 
> This patch adds the support for thermal sensor of Hi3660 SoC.

for the Hi3660 SoC thermal sensor.

> this will register sensors for thermal framework and use device
> tree to bind cooling device.

Is it possible to give a pointer to some documentation or to describe
the hardware?

An explanation of the adc min max coef[] range[] conversion would be nice.

In addition, having the rational behind the average and the max would be
nice. Do we really need both avg and max as virtual sensor?

> Signed-off-by: Tao Wang <kevin.wangtao@...aro.org>
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> ---
>  drivers/thermal/Kconfig        |  13 +++
>  drivers/thermal/Makefile       |   1 +
>  drivers/thermal/hisi_tsensor.c | 209 +++++++++++++++++++++++++++++++++++++++++


IMO, we don't need a new file, but merge this code with the current
hisi_thermal.c driver. BTW, the hi6220 has also a tsensor which is
different from this one.

I suggest to base the hi3660 thermal driver on top of the cleanup I sent
for the hi6220.

>  3 files changed, 223 insertions(+)
>  create mode 100644 drivers/thermal/hisi_tsensor.c
> 
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index b5b5fac..32f582d 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -203,6 +203,19 @@ config HISI_THERMAL
>  	  thermal framework. cpufreq is used as the cooling device to throttle
>  	  CPUs when the passive trip is crossed.
>  
> +config HISI_TSENSOR
> +	tristate "Hisilicon tsensor driver"
> +	depends on ARCH_HISI || COMPILE_TEST
> +	depends on HAS_IOMEM
> +	depends on OF
> +	default y
> +	help
> +	  Enable this to plug Hisilicon's tsensor driver into the Linux thermal
> +	  framework. Besides all the hardware sensors, this also support two
> +	  virtual sensors, one for maximum of all the hardware sensor, and
> +	  one for average of all the hardware sensor.
> +	  Compitable with Hi3660 or higher.

s/Compitable/Compatible/

> +
>  config IMX_THERMAL
>  	tristate "Temperature sensor driver for Freescale i.MX SoCs"
>  	depends on (ARCH_MXC && CPU_THERMAL) || COMPILE_TEST
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index 094d703..8a16bd4 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -56,6 +56,7 @@ obj-$(CONFIG_ST_THERMAL)	+= st/
>  obj-$(CONFIG_QCOM_TSENS)	+= qcom/
>  obj-$(CONFIG_TEGRA_SOCTHERM)	+= tegra/
>  obj-$(CONFIG_HISI_THERMAL)     += hisi_thermal.o
> +obj-$(CONFIG_HISI_TSENSOR)	+= hisi_tsensor.o
>  obj-$(CONFIG_MTK_THERMAL)	+= mtk_thermal.o
>  obj-$(CONFIG_GENERIC_ADC_THERMAL)	+= thermal-generic-adc.o
>  obj-$(CONFIG_ZX2967_THERMAL)	+= zx2967_thermal.o
> diff --git a/drivers/thermal/hisi_tsensor.c b/drivers/thermal/hisi_tsensor.c
> new file mode 100644
> index 0000000..34cf2ba
> --- /dev/null
> +++ b/drivers/thermal/hisi_tsensor.c
> @@ -0,0 +1,209 @@
> +/*
> + *  linux/drivers/thermal/hisi_tsensor.c
> + *
> + *  Copyright (c) 2017 Hisilicon Limited.
> + *  Copyright (c) 2017 Linaro Limited.
> + *
> + *  Author: Tao Wang <kevin.wangtao@...aro.org>
> + *  Author: Leo Yan <leo.yan@...aro.org>
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; version 2 of the License.
> + *
> + *  This program is distributed in the hope that it will be useful,
> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *  GNU General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/thermal.h>
> +
> +#include "thermal_core.h"
> +
> +#define VIRTUAL_SENSORS		2
> +
> +/* hisi Thermal Sensor Dev Structure */
> +struct hisi_thermal_sensor {
> +	struct hisi_thermal_data *thermal;
> +	struct thermal_zone_device *tzd;
> +	void __iomem *sensor_reg;
> +	unsigned int id;
> +};
> +
> +struct hisi_thermal_data {
> +	struct platform_device *pdev;
> +	struct hisi_thermal_sensor *sensors;
> +	unsigned int range[2];
> +	unsigned int coef[2];
> +	unsigned int max_hw_sensor;
> +};
> +
> +static int hisi_thermal_get_temp(void *_sensor, int *temp)
> +{
> +	struct hisi_thermal_sensor *sensor = _sensor;
> +	struct hisi_thermal_data *data = sensor->thermal;
> +	unsigned int idx, adc_min, adc_max, max_sensor;
> +	int val, average = 0, max = 0;
> +
> +	adc_min = data->range[0];
> +	adc_max = data->range[1];
> +	max_sensor = data->max_hw_sensor;
> +
> +	if (sensor->id < max_sensor) {
> +		val = readl(sensor->sensor_reg);
> +		val = clamp_val(val, adc_min, adc_max);

That looks a bit fuzzy. Why not create a get_temp for physical sensor
and another one for the virtual? So there will be a clear distinction
between both.

> +	} else {
> +		for (idx = 0; idx < max_sensor; idx++) {
> +			val = readl(data->sensors[idx].sensor_reg);

Below, it is assumed thermal_zone_of_sensor_register() can fail and
sensor->tzd becomes NULL. But no check is done here with the sensor's
tzd. Shall the code assume we take all the sensors even if a thermal
zone failed to register ?

> +			val = clamp_val(val, adc_min, adc_max);
> +			average += val;
> +			if (val > max)
> +				max = val;
> +		}
> +
> +		if (sensor->id == max_sensor)
> +			val = max;
> +		else
> +			val = average / max_sensor;
> +	}
>
> +	*temp = ((val - adc_min) * data->coef[0]) / (adc_max - adc_min)
> +		+ data->coef[1];

Pre-compute (adc_max - adc_min) at init time and check it is greater
than zero, otherwise for a bad DT configuration we can end up with
division by zero and crash the kernel (assuming having adc ranges in the
DT is what we want).

> +	return 0;
> +}
> +
> +static struct thermal_zone_of_device_ops hisi_of_thermal_ops = {
> +	.get_temp = hisi_thermal_get_temp,
> +};
> +
> +static void hisi_thermal_toggle_sensor(struct hisi_thermal_sensor *sensor,
> +				       bool on)
> +{
> +	struct thermal_zone_device *tzd = sensor->tzd;
> +
> +	tzd->ops->set_mode(tzd,
> +		on ? THERMAL_DEVICE_ENABLED : THERMAL_DEVICE_DISABLED);
> +}
> +
> +static int hisi_thermal_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct hisi_thermal_data *data;
> +	struct hisi_thermal_sensor *sensor;
> +	struct resource *res;
> +	unsigned int max_sensor;
> +	int ret, i;
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->pdev = pdev;
> +	ret = of_property_read_u32(np, "hisi,tsensors", &max_sensor);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to get max sensor\n");
> +		return -EINVAL;
> +	}
> +	data->max_hw_sensor = max_sensor;

Do we really need a max sensor definition in the DT? Isn't it something
we can deduce by looping with platform_get_resource below ?

eg.

while ((res = platform_get_resource(..., num_sensor++)) {
	...
}

That said, I think we can assume there are 3 sensors always, no?

> +	data->sensors = devm_kzalloc(dev,
> +		sizeof(*data->sensors) * (max_sensor + VIRTUAL_SENSORS),
> +		GFP_KERNEL);
> +	if (IS_ERR(data->sensors)) {

s/IS_ERR(data->sensors)/!data->sensors/

> +		dev_err(dev, "failed to alloc sensors\n");

No message on memory allocation failure, there is already one from the
mm framework.

> +		return -ENOMEM;
> +	}
> +
> +	ret = of_property_read_u32_array(np, "hisi,coef", data->coef, 2);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to get coef\n");
> +		return -EINVAL;

return ret;

> +	}
> +
> +	ret = of_property_read_u32_array(np, "hisi,adc-range", data->range, 2);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to get range\n");
> +		return -EINVAL;

return ret;

> +	}

Are these data really needed through DT? Isn't it something we can hardcode?

> +	platform_set_drvdata(pdev, data);
> +
> +	for (i = 0; i < max_sensor + VIRTUAL_SENSORS; ++i) {
> +		sensor = &data->sensors[i];
> +		if (i < max_sensor) {
> +			res = platform_get_resource(pdev, IORESOURCE_MEM, i);

Error check?

> +			sensor->sensor_reg = devm_ioremap_resource(dev, res);
> +			if (IS_ERR(sensor->sensor_reg)) {
> +				dev_err(dev, "failed to get reg base\n");
> +				return -ENOMEM;

s/-ENOMEM/PTR_ERR(sensor->sensor_reg)/

> +			}
> +		}
> +
> +		sensor->id = i;

How can we deal with holes in the DT?

> +		sensor->thermal = data;
> +		sensor->tzd = thermal_zone_of_sensor_register(dev,
> +				i, sensor, &hisi_of_thermal_ops);
> +		if (IS_ERR(sensor->tzd)) {
> +			sensor->tzd = NULL;
> +		} else {
> +			hisi_thermal_toggle_sensor(sensor, true);
> +			dev_info(dev, "thermal sensor%d registered\n", i);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int hisi_thermal_exit(struct platform_device *pdev)
> +{
> +	struct hisi_thermal_data *data = platform_get_drvdata(pdev);
> +	int i;
> +
> +	for (i = 0; i < data->max_hw_sensor + VIRTUAL_SENSORS; i++) {
> +		struct hisi_thermal_sensor *sensor = &data->sensors[i];
> +
> +		if (!sensor->tzd)
> +			continue;
> +
> +		hisi_thermal_toggle_sensor(sensor, false);
> +		thermal_zone_of_sensor_unregister(&pdev->dev, sensor->tzd);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id hisi_thermal_id_table[] = {
> +	{ .compatible = "hisilicon,hi3660-tsensor" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, hisi_thermal_id_table);
> +
> +static struct platform_driver hisi_thermal_driver = {
> +	.probe = hisi_thermal_probe,
> +	.remove = hisi_thermal_exit,
> +	.driver = {
> +		.name = "hisi_tsensor",
> +		.of_match_table = hisi_thermal_id_table,
> +	},
> +};
> +
> +module_platform_driver(hisi_thermal_driver);
> +
> +MODULE_AUTHOR("Tao Wang <kevin.wangtao@...aro.org>");
> +MODULE_AUTHOR("Leo Yan <leo.yan@...aro.org>");
> +MODULE_DESCRIPTION("hisi tsensor driver");
> +MODULE_LICENSE("GPL v2");
> 


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