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Date:   Sun, 12 May 2019 15:39:30 +0200
From:   Maxime Ripard <maxime.ripard@bootlin.com>
To:     Yangtao Li <tiny.windzz@gmail.com>
Cc:     rui.zhang@intel.com, edubezval@gmail.com,
        daniel.lezcano@linaro.org, robh+dt@kernel.org,
        mark.rutland@arm.com, wens@csie.org, catalin.marinas@arm.com,
        will.deacon@arm.com, davem@davemloft.net,
        mchehab+samsung@kernel.org, gregkh@linuxfoundation.org,
        Jonathan.Cameron@huawei.com, nicolas.ferre@microchip.com,
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        marc.w.gonzalez@free.fr, stefan.wahren@i2se.com,
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        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] thermal: sun50i: add thermal driver for h6
Message-ID: <20190512133930.t5txssl7mou2gljt@flea>
References: <20190512082614.9045-1-tiny.windzz@gmail.com>
 <20190512082614.9045-3-tiny.windzz@gmail.com>
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Hi,

Thanks a lot for working on this!

On Sun, May 12, 2019 at 04:26:13AM -0400, Yangtao Li wrote:
> This patch adds the support for allwinner thermal sensor, within
> allwinner SoC. It will register sensors for thermal framework
> and use device tree to bind cooling device.
>
> Based on driver code found here:
> https://megous.com/git/linux and https://github.com/Allwinner-Homlet/H6-BSP4.9-linux

I wouldn't place the URL in the commit log. The commit log stays
forever in the linux history. Git repos and branches are going away
over time.

> Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
> ---
>  MAINTAINERS                      |   7 +
>  drivers/thermal/Kconfig          |  14 ++
>  drivers/thermal/Makefile         |   1 +
>  drivers/thermal/sun50i_thermal.c | 357 +++++++++++++++++++++++++++++++

The long term goal is to support all the thermal sensors, not just the
H6. Since that controller was introduced with the sun8i family, it
makes more sense to use that prefix for the driver and the functions.

>  4 files changed, 379 insertions(+)
>  create mode 100644 drivers/thermal/sun50i_thermal.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3c65228e93c5..8da56582e72a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -674,6 +674,13 @@ L:	linux-crypto@vger.kernel.org
>  S:	Maintained
>  F:	drivers/crypto/sunxi-ss/
>
> +ALLWINNER THERMAL DRIVER
> +M:	Yangtao Li <tiny.windzz@gmail.com>
> +L:	linux-pm@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/thermal/sun50i-thermal.txt
> +F:	drivers/thermal/sun50i_thermal.c
> +
>  ALLWINNER VPU DRIVER
>  M:	Maxime Ripard <maxime.ripard@bootlin.com>
>  M:	Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 653aa27a25a4..2a8d1c98c6ca 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -252,6 +252,20 @@ config SPEAR_THERMAL
>  	  Enable this to plug the SPEAr thermal sensor driver into the Linux
>  	  thermal framework.
>
> +config SUN50I_THERMAL
> +	tristate "Allwinner sun50i thermal driver"
> +	depends on ARCH_SUNXI || COMPILE_TEST
> +	depends on HAS_IOMEM
> +	depends on NVMEM
> +	depends on OF
> +	depends on RESET_CONTROLLER
> +	help
> +	  Support for the sun50i thermal sensor driver into the Linux thermal
> +	  framework.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called sun50i-thermal.
> +
>  config ROCKCHIP_THERMAL
>  	tristate "Rockchip thermal driver"
>  	depends on ARCH_ROCKCHIP || COMPILE_TEST
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index 486d682be047..a09b30b90003 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -30,6 +30,7 @@ thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
>  # platform thermal drivers
>  obj-y				+= broadcom/
>  obj-$(CONFIG_SPEAR_THERMAL)	+= spear_thermal.o
> +obj-$(CONFIG_SUN50I_THERMAL)	+= sun50i_thermal.o
>  obj-$(CONFIG_ROCKCHIP_THERMAL)	+= rockchip_thermal.o
>  obj-$(CONFIG_RCAR_THERMAL)	+= rcar_thermal.o
>  obj-$(CONFIG_RCAR_GEN3_THERMAL)	+= rcar_gen3_thermal.o
> diff --git a/drivers/thermal/sun50i_thermal.c b/drivers/thermal/sun50i_thermal.c
> new file mode 100644
> index 000000000000..3bdb3677b3d4
> --- /dev/null
> +++ b/drivers/thermal/sun50i_thermal.c
> @@ -0,0 +1,357 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Thermal sensor driver for Allwinner SOC
> + * Copyright (C) 2019 Yangtao Li
> + *
> + * Based on the work of Icenowy Zheng <icenowy@aosc.io>
> + * Based on the work of Ondrej Jirman <megous@megous.com>
> + * Based on the work of Josef Gajdusek <atx@atx.name>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/nvmem-consumer.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/reset.h>
> +#include <linux/slab.h>
> +#include <linux/thermal.h>
> +
> +#define MAX_SENSOR_NUM	4
> +
> +#define FT_TEMP_MASK				GENMASK(11, 0)
> +#define TEMP_CALIB_MASK				GENMASK(11, 0)
> +#define TEMP_TO_REG				672
> +#define CALIBRATE_DEFAULT			0x800
> +
> +#define SUN50I_THS_CTRL0			0x00
> +#define SUN50I_H6_THS_ENABLE			0x04
> +#define SUN50I_H6_THS_PC			0x08
> +#define SUN50I_H6_THS_MFC			0x30
> +#define SUN50I_H6_TEMP_CALIB			0xa0
> +#define SUN50I_H6_TEMP_DATA			0xc0
> +
> +#define SUN50I_THS_CTRL0_T_ACQ(x)		((GENMASK(15, 0) & (x)) << 16)
> +#define SUN50I_THS_FILTER_EN			BIT(2)
> +#define SUN50I_THS_FILTER_TYPE(x)		(GENMASK(1, 0) & (x))
> +#define SUN50I_H6_THS_PC_TEMP_PERIOD(x)		((GENMASK(19, 0) & (x)) << 12)
> +
> +/* millidegree celsius */
> +#define SUN50I_H6_FT_DEVIATION			7000
> +
> +struct tsens_device;
> +
> +struct tsensor {
> +	struct tsens_device		*tmdev;
> +	struct thermal_zone_device	*tzd;
> +	int				id;
> +};
> +
> +struct sun50i_thermal_chip {
> +	int	sensor_num;
> +	int	offset;
> +	int	scale;
> +	int	ft_deviation;
> +	int	temp_calib_base;
> +	int	temp_data_base;
> +	int	(*enable)(struct tsens_device *tmdev);
> +	int	(*disable)(struct tsens_device *tmdev);
> +};

I'm not super fond of having a lot of quirks that are not needed. If
we ever need those quirks when adding support for a new SoC, then
yeah, we should totally have some, but only when and if it's needed.

Otherwise, the driver is more complicated for no particular reason.

> +
> +struct tsens_device {

IIRC the acronym used by allwinner is THS, maybe we can just use that
as a prefix?

> +	const struct sun50i_thermal_chip	*chip;
> +	struct device				*dev;
> +	struct regmap				*regmap;
> +	struct reset_control			*reset;
> +	struct clk				*bus_clk;
> +	struct tsensor				sensor[MAX_SENSOR_NUM];
> +};
> +
> +/* Temp Unit: millidegree Celsius */
> +static int tsens_reg2temp(struct tsens_device *tmdev,
> +			      int reg)
> +{
> +	return (reg + tmdev->chip->offset) * tmdev->chip->scale;
> +}
> +
> +static int tsens_get_temp(void *data, int *temp)
> +{
> +	struct tsensor *s = data;
> +	struct tsens_device *tmdev = s->tmdev;
> +	int val;
> +
> +	regmap_read(tmdev->regmap, tmdev->chip->temp_data_base +
> +		    0x4 * s->id, &val);
> +
> +	if (unlikely(val == 0))
> +		return -EBUSY;

I'm not sure why a val equals to 0 would be associated with EBUSY?

Also, it's not in a fast path, so you can drop the unlikely. Chances
are it's not that unlikely anyway.

> +	*temp = tsens_reg2temp(tmdev, val);
> +	if (tmdev->chip->ft_deviation)
> +		*temp += tmdev->chip->ft_deviation;
> +
> +	return 0;
> +}
> +
> +static const struct thermal_zone_of_device_ops tsens_ops = {
> +	.get_temp = tsens_get_temp,
> +};
> +
> +static const struct regmap_config config = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.fast_io = true,
> +};
> +
> +static int tsens_init(struct tsens_device *tmdev)
> +{
> +	struct device *dev = tmdev->dev;
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct resource *mem;
> +	void __iomem *base;
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(dev, mem);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	tmdev->regmap = devm_regmap_init_mmio_clk(dev, "bus",
> +						  base,
> +						  &config);
> +	if (IS_ERR(tmdev->regmap))
> +		return PTR_ERR(tmdev->regmap);
> +
> +	tmdev->reset = devm_reset_control_get(dev, "bus");
> +	if (IS_ERR(tmdev->reset))
> +		return PTR_ERR(tmdev->reset);
> +
> +	tmdev->bus_clk = devm_clk_get(&pdev->dev, "bus");
> +	if (IS_ERR(tmdev->bus_clk))
> +		return PTR_ERR(tmdev->bus_clk);

You don't need to get that clock if regmap has it already.

> +	return 0;
> +}
> +
> +/*
> + * Even if the external calibration data stored in sid is not accessible,
> + * the THS hardware can still work, although the data won't be so accurate.
> + * The default value of calibration register is 0x800 for every sensor,
> + * and the calibration value is usually 0x7xx or 0x8xx, so they won't be
> + * away from the default value for a lot.
> + *
> + * So here we do not return error if the calibartion data is
> + * not available, except the probe needs deferring.
> + */
> +static int tsens_calibrate(struct tsens_device *tmdev)
> +{
> +	struct nvmem_cell *calcell;
> +	struct device *dev = tmdev->dev;
> +	u16 *caldata;
> +	size_t callen;
> +	int ft_temp;
> +	int i = 0;
> +
> +	calcell = devm_nvmem_cell_get(dev, "calib");
> +	if (IS_ERR(calcell)) {
> +		if (PTR_ERR(calcell) == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +
> +		goto out;
> +	}
> +
> +	caldata = nvmem_cell_read(calcell, &callen);
> +	if (IS_ERR(caldata))
> +		goto out;
> +
> +	if (!caldata[0] || callen < 2 + 2 * tmdev->chip->sensor_num)
> +		goto out_free;

The first part of your or isn't obvious and should have a comment.

The second part shouldn't return 0 but an error

> +
> +	/*
> +	 * The calbration data on H6 is stored as temperature-value
> +	 * pair when being filled at factory test stage.
> +	 * The unit of stored FT temperature is 0.1 degreee celusis.
> +	 */
> +	ft_temp = caldata[0] & FT_TEMP_MASK;
> +
> +	for (; i < tmdev->chip->sensor_num; i++) {

Usually you would initialize i here, and not when declared.

> +		int reg = (int)caldata[i + 1];
> +		int sensor_temp = tsens_reg2temp(tmdev, reg);
> +		int delta, cdata, calib_offest;
> +
> +		/*
> +		 * To calculate the calibration value:
> +		 *
> +		 * X(in Celsius) = Ts - ft_temp
> +		 * delta = X * 10000 / TEMP_TO_REG
> +		 * cdata = CALIBRATE_DEFAULT - delta
> +		 *
> +		 * cdata: calibration value
> +		 */
> +		delta = (sensor_temp - ft_temp * 100) * 10 / TEMP_TO_REG;
> +		cdata = CALIBRATE_DEFAULT - delta;
> +		if (cdata & ~TEMP_CALIB_MASK) {
> +			dev_warn(dev, "sensor%d calibration value error", i);
> +
> +			continue;
> +		}
> +
> +		calib_offest = tmdev->chip->temp_calib_base + (i / 2) * 0x4;
> +
> +		if (i % 2) {
> +			int val;
> +
> +			regmap_read(tmdev->regmap, calib_offest, &val);
> +			val = (val & TEMP_CALIB_MASK) | (cdata << 16);
> +			regmap_write(tmdev->regmap, calib_offest, val);
> +		} else
> +			regmap_write(tmdev->regmap, calib_offest, cdata);

This should have brackets as well

> +	}
> +
> +out_free:
> +	kfree(caldata);
> +out:
> +	return 0;
> +}
> +
> +static int tsens_register(struct tsens_device *tmdev)
> +{
> +	struct thermal_zone_device *tzd;
> +	int i = 0;
> +
> +	for (; i < tmdev->chip->sensor_num; i++) {

Ditto

> +		tmdev->sensor[i].tmdev = tmdev;
> +		tmdev->sensor[i].id = i;
> +		tmdev->sensor[i].tzd = devm_thermal_zone_of_sensor_register(
> +					tmdev->dev, i, &tmdev->sensor[i],
> +					&tsens_ops);
> +		if (IS_ERR(tmdev->sensor[i].tzd))
> +			return PTR_ERR(tzd);
> +	}
> +
> +	return 0;
> +}
> +
> +static int tsens_probe(struct platform_device *pdev)
> +{
> +	struct tsens_device *tmdev;
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	tmdev = devm_kzalloc(dev, sizeof(*tmdev), GFP_KERNEL);
> +	if (!tmdev)
> +		return -ENOMEM;
> +
> +	tmdev->dev = dev;
> +	tmdev->chip = of_device_get_match_data(&pdev->dev);
> +	if (!tmdev->chip)
> +		return -EINVAL;
> +
> +	ret = tsens_init(tmdev);
> +	if (ret)
> +		return ret;
> +
> +	ret = tsens_register(tmdev);
> +	if (ret)
> +		return ret;
> +
> +	ret = tmdev->chip->enable(tmdev);
> +	if (ret)
> +		return ret;
>
> +	platform_set_drvdata(pdev, tmdev);

Your registration should be the very last thing you do. Otherwise, you
have a small window where the get_temp callback can be called, but the
driver will not be functional yet.

> +	return ret;
> +}
> +
> +static int tsens_remove(struct platform_device *pdev)
> +{
> +	struct tsens_device *tmdev = platform_get_drvdata(pdev);
> +
> +	tmdev->chip->disable(tmdev);
> +
> +	return 0;
> +}
> +
> +static int sun50i_thermal_enable(struct tsens_device *tmdev)
> +{
> +	int ret, val;
> +
> +	ret = reset_control_deassert(tmdev->reset);
> +	if (ret)
> +		return ret;
> +
> +	ret = clk_prepare_enable(tmdev->bus_clk);
> +	if (ret)
> +		goto assert_reset;

This is done by regmap as well

> +	ret = tsens_calibrate(tmdev);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * clkin = 24MHz
> +	 * T acquire = clkin / (SUN50I_THS_CTRL0_T_ACQ + 1)
> +	 *           = 20us
> +	 */
> +	regmap_write(tmdev->regmap, SUN50I_THS_CTRL0,
> +		     SUN50I_THS_CTRL0_T_ACQ(479));
> +	/* average over 4 samples */
> +	regmap_write(tmdev->regmap, SUN50I_H6_THS_MFC,
> +		     SUN50I_THS_FILTER_EN |
> +		     SUN50I_THS_FILTER_TYPE(1));
> +	/* period = (SUN50I_H6_THS_PC_TEMP_PERIOD + 1) * 4096 / clkin; ~10ms */
> +	regmap_write(tmdev->regmap, SUN50I_H6_THS_PC,
> +		     SUN50I_H6_THS_PC_TEMP_PERIOD(58));
> +	/* enable sensor */
> +	val = GENMASK(tmdev->chip->sensor_num - 1, 0);
> +	regmap_write(tmdev->regmap, SUN50I_H6_THS_ENABLE, val);
> +
> +	return 0;
> +
> +assert_reset:
> +	reset_control_assert(tmdev->reset);
> +
> +	return ret;

Can't we do that with runtime_pm?

Thanks!
Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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