Message-ID: <20210617150740.GA2676642@roeck-us.net>
Date:   Thu, 17 Jun 2021 08:07:40 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Emil Renner Berthing <kernel@...il.dk>
Cc:     Jean Delvare <jdelvare@...e.com>, Rob Herring <robh+dt@...nel.org>,
        Samin Guo <samin.guo@...rfivetech.com>,
        linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] hwmon: (sfctemp) Add StarFive JH7100 temperature
 sensor

On Wed, Jun 16, 2021 at 08:15:45PM +0200, Emil Renner Berthing wrote:
> Register definitions based on sfctemp driver in the StarFive
> 5.10 kernel by Samin Guo <samin.guo@...rfivetech.com>.
> 
> Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
> ---
> 
> @Samin: Only the register definitions and conversion constants are left
> from your driver, but still it would be really nice if you could reply
> to this mail with your Signed-off-by. Thanks!
> 
> 
>  drivers/hwmon/Kconfig   |   9 ++
>  drivers/hwmon/Makefile  |   1 +
>  drivers/hwmon/sfctemp.c | 309 ++++++++++++++++++++++++++++++++++++++++

Documentation/hwmon/sfctemp is missing.

>  3 files changed, 319 insertions(+)
>  create mode 100644 drivers/hwmon/sfctemp.c
> 
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 87624902ea80..fa7562920dfa 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1751,6 +1751,15 @@ config SENSORS_STTS751
>  	  This driver can also be built as a module. If so, the module
>  	  will be called stts751.
>  
> +config SENSORS_SFCTEMP
> +	tristate "Starfive JH7100 temperature sensor"
> +	help
> +	  If you say yes here you get support for temperature sensor
> +	  on the Starfive JH7100 SoC.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called sfctemp.
> +
>  config SENSORS_SMM665
>  	tristate "Summit Microelectronics SMM665"
>  	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 59e78bc212cf..3723eb580bf3 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_SBTSI)	+= sbtsi_temp.o
>  obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
>  obj-$(CONFIG_SENSORS_SCH5627)	+= sch5627.o
>  obj-$(CONFIG_SENSORS_SCH5636)	+= sch5636.o
> +obj-$(CONFIG_SENSORS_SFCTEMP)	+= sfctemp.o
>  obj-$(CONFIG_SENSORS_SL28CPLD)	+= sl28cpld-hwmon.o
>  obj-$(CONFIG_SENSORS_SHT15)	+= sht15.o
>  obj-$(CONFIG_SENSORS_SHT21)	+= sht21.o
> diff --git a/drivers/hwmon/sfctemp.c b/drivers/hwmon/sfctemp.c
> new file mode 100644
> index 000000000000..62a838063e4e
> --- /dev/null
> +++ b/drivers/hwmon/sfctemp.c
> @@ -0,0 +1,309 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021 Emil Renner Berthing <kernel@...il.dk>
> + * Copyright (C) 2021 Samin Guo <samin.guo@...rfivetech.com>
> + */
> +#include <linux/completion.h>
> +#include <linux/delay.h>
> +#include <linux/hwmon.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>

This may work on some systems, but on others it will result in:

drivers/hwmon/sfctemp.c: In function ‘sfctemp_power_up’:
drivers/hwmon/sfctemp.c:76:2: error: implicit declaration of function ‘writel’

drivers/hwmon/sfctemp.c: In function ‘sfctemp_convert’:
drivers/hwmon/sfctemp.c:144:17: error: implicit declaration of function ‘readl’

It is necessary to include <linux/io.h>.

> +
> +/* TempSensor reset. The RSTN can be de-asserted once the analog core has
> + * powered up. Trst(min 100ns)
> + * 0:reset  1:de-assert */

/*
 * Please use standard multi-line comments.
 * checkpatch would tell you, plus it has other complaints.
 * Please run checkpatch --strict and fix what it reports.
 */
> +#define SFCTEMP_RSTN     BIT(0)
> +
> +/* TempSensor analog core power down. The analog core will be powered up
> + * Tpu(min 50us) after PD is de-asserted. RSTN should be held low until the
> + * analog core is powered up.
> + * 0:power up  1:power down */
> +#define SFCTEMP_PD       BIT(1)
> +
> +/* TempSensor start conversion enable.
> + * 0:disable  1:enable */
> +#define SFCTEMP_RUN      BIT(2)
> +
> +/* TempSensor calibration mode enable.
> + * 0:disable  1:enable */
> +#define SFCTEMP_CAL      BIT(4)
> +
> +/* TempSensor signature enable. Generate a toggle value outputting on DOUT for
> + * test purpose.
> + * 0:disable  1:enable */
> +#define SFCTEMP_SGN      BIT(5)
> +
> +/* TempSensor test access control.
> + * 0000:normal 0001:Test1  0010:Test2  0011:Test3
> + * 0100:Test4  1000:Test8  1001:Test9 */
> +#define SFCTEMP_TM_Pos   12
> +#define SFCTEMP_TM_Msk   GENMASK(15, 12)

Defines should upper case. Besides, the above defines are not
used. Please remove unused defines, and please rename the others
to be upper case only.

> +
> +/* TempSensor conversion value output.
> + * Temp(c)=DOUT*Y/4094 - K */
> +#define SFCTEMP_DOUT_Pos 16
> +#define SFCTEMP_DOUT_Msk GENMASK(27, 16)
> +
> +/* TempSensor digital test output. */
> +#define SFCTEMP_DIGO     BIT(31)
> +
> +/* DOUT to Celcius conversion constants */
> +#define SFCTEMP_Y1000 237500L
> +#define SFCTEMP_Z       4094L

Please use

#define<space><definition><tab><value>, eg

#define SFCTEMP_Y1000	237500L
#define SFCTEMP_Z	4094L

for all defines.

> +#define SFCTEMP_K1000  81100L
> +
> +struct sfctemp {
> +	struct mutex lock;
> +	struct completion conversion_done;
> +	void __iomem *regs;
> +	bool enabled;
> +};
> +
> +static irqreturn_t sfctemp_isr(int irq, void *data)
> +{
> +	struct sfctemp *sfctemp = data;
> +
> +	complete(&sfctemp->conversion_done);
> +	return IRQ_HANDLED;
> +}
> +
> +static void sfctemp_power_up(struct sfctemp *sfctemp)
> +{
> +	/* make sure we're powered down first */
> +	writel(SFCTEMP_PD, sfctemp->regs);
> +	udelay(1);
> +
> +	writel(0, sfctemp->regs);
> +	/* wait t_pu(50us) + t_rst(100ns) */
> +	usleep_range(60, 200);
> +
> +	/* de-assert reset */
> +	writel(SFCTEMP_RSTN, sfctemp->regs);
> +	udelay(1); /* wait t_su(500ps) */
> +}
> +
> +static void sfctemp_power_down(struct sfctemp *sfctemp)
> +{
> +	writel(SFCTEMP_PD, sfctemp->regs);
> +}
> +
> +static void sfctemp_run_single(struct sfctemp *sfctemp)
> +{
> +	writel(SFCTEMP_RSTN | SFCTEMP_RUN, sfctemp->regs);
> +	udelay(1);
> +	writel(SFCTEMP_RSTN, sfctemp->regs);
> +}
> +
> +static int sfctemp_enable(struct sfctemp *sfctemp)
> +{
> +	mutex_lock(&sfctemp->lock);
> +	if (sfctemp->enabled)
> +		goto done;
> +
> +	sfctemp_power_up(sfctemp);
> +	sfctemp->enabled = true;
> +done:
> +	mutex_unlock(&sfctemp->lock);
> +	return 0;
> +}
> +
> +static int sfctemp_disable(struct sfctemp *sfctemp)
> +{
> +	mutex_lock(&sfctemp->lock);
> +	if (!sfctemp->enabled)
> +		goto done;
> +
> +	sfctemp_power_down(sfctemp);
> +	sfctemp->enabled = false;
> +done:
> +	mutex_unlock(&sfctemp->lock);
> +	return 0;
> +}
> +
> +static int sfctemp_convert(struct sfctemp *sfctemp, long *val)
> +{
> +	long ret;

Why long ? Sure, wait_for_completion_interruptible_timeout()
returns a long, but it will never return a value large enough to warrant
a long here.

> +
> +	mutex_lock(&sfctemp->lock);
> +	if (!sfctemp->enabled) {
> +		ret = -ENODATA;
> +		goto out;
> +	}
> +
> +	sfctemp_run_single(sfctemp);
> +
> +	ret = wait_for_completion_interruptible_timeout(&sfctemp->conversion_done,
> +			                                msecs_to_jiffies(10));
> +	if (ret < 0)
> +		goto out;
> +
> +	/* calculate temperature in milli Celcius */
> +	*val = (long)((readl(sfctemp->regs) & SFCTEMP_DOUT_Msk) >> SFCTEMP_DOUT_Pos)
> +		* SFCTEMP_Y1000 / SFCTEMP_Z - SFCTEMP_K1000;
> +
> +	ret = 0;
> +out:
> +	mutex_unlock(&sfctemp->lock);
> +	return ret;
> +}
> +
> +static umode_t sfctemp_is_visible(const void *data, enum hwmon_sensor_types type,
> +				  u32 attr, int channel)
> +{
> +	switch (type) {
> +	case hwmon_temp:
> +		switch (attr) {
> +		case hwmon_temp_enable:
> +			return 0644;
> +		case hwmon_temp_input:
> +			return 0444;
> +		}
> +		return 0;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static int sfctemp_read(struct device *dev, enum hwmon_sensor_types type,
> +			u32 attr, int channel, long *val)
> +{
> +	struct sfctemp *sfctemp = dev_get_drvdata(dev);
> +
> +	switch (type) {
> +	case hwmon_temp:
> +		switch (attr) {
> +		case hwmon_temp_enable:
> +			*val = sfctemp->enabled;
> +			return 0;
> +		case hwmon_temp_input:
> +			return sfctemp_convert(sfctemp, val);
> +		}
> +		return -EINVAL;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int sfctemp_write(struct device *dev, enum hwmon_sensor_types type,
> +			 u32 attr, int channel, long val)
> +{
> +	struct sfctemp *sfctemp = dev_get_drvdata(dev);
> +
> +	switch (type) {
> +	case hwmon_temp:
> +		switch (attr) {
> +		case hwmon_temp_enable:
> +			if (val == 0)
> +				return sfctemp_disable(sfctemp);
> +			if (val == 1)
> +				return sfctemp_enable(sfctemp);
> +			break;
> +		}
> +		return -EINVAL;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct hwmon_channel_info *sfctemp_info[] = {
> +	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
> +	HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT),
> +	NULL
> +};
> +
> +static const struct hwmon_ops sfctemp_hwmon_ops = {
> +	.is_visible = sfctemp_is_visible,
> +	.read = sfctemp_read,
> +	.write = sfctemp_write,
> +};
> +
> +static const struct hwmon_chip_info sfctemp_chip_info = {
> +	.ops = &sfctemp_hwmon_ops,
> +	.info = sfctemp_info,
> +};
> +
> +static int sfctemp_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device *hwmon_dev;
> +	struct resource *mem;
> +	struct sfctemp *sfctemp;
> +	long val;
> +	int ret;
> +
> +	sfctemp = devm_kzalloc(dev, sizeof(*sfctemp), GFP_KERNEL);
> +	if (!sfctemp)
> +		return -ENOMEM;
> +
> +	dev_set_drvdata(dev, sfctemp);
> +	mutex_init(&sfctemp->lock);
> +	init_completion(&sfctemp->conversion_done);
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	sfctemp->regs = devm_ioremap_resource(dev, mem);
> +	if (IS_ERR(sfctemp->regs))
> +		return PTR_ERR(sfctemp->regs);
> +
> +	ret = platform_get_irq(pdev, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = devm_request_irq(dev, ret, sfctemp_isr,
> +			       IRQF_SHARED, pdev->name, sfctemp);
> +	if (ret) {
> +		dev_err(dev, "request irq failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = sfctemp_enable(sfctemp);
> +	if (ret)
> +		return ret;

Please consider adding devm_add_action_or_reset() to disable the sensor.
Then you can use devm_hwmon_device_register_with_info(), and there is
no need for a remove function.
> +
> +	hwmon_dev = hwmon_device_register_with_info(dev, pdev->name, sfctemp,
> +						    &sfctemp_chip_info, NULL);
> +	if (IS_ERR(hwmon_dev))
> +		return PTR_ERR(hwmon_dev);
> +
> +	/* do a conversion to check everything works */
> +	ret = sfctemp_convert(sfctemp, &val);

Please drop this check; it will result in substantial boot delays.
The assumption is the the hardware works; the system should not be
optimized (slowed down) to handle a potential and hopefully rare
failure case.

> +	if (ret) {
> +		hwmon_device_unregister(hwmon_dev);
> +		return ret;
> +	}
> +
> +	dev_info(dev, "%ld.%03ld C\n", val / 1000, val % 1000);

Please drop this message. Anyone interested in boot-time temperature
readings can add a script and get it from sysfs attributes as needed.

> +	return 0;
> +}
> +
> +static int sfctemp_remove(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct sfctemp *sfctemp = dev_get_drvdata(dev);
> +
> +	hwmon_device_unregister(dev);
> +	return sfctemp_disable(sfctemp);
> +}
> +
> +static const struct of_device_id sfctemp_of_match[] = {
> +	{ .compatible = "starfive,jh7100-temp" },
> +	{ /* sentinel */ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, sfctemp_of_match);
> +
> +static struct platform_driver sfctemp_driver = {
> +	.driver = {
> +		.name = "sfctemp",
> +		.of_match_table = of_match_ptr(sfctemp_of_match),
> +	},
> +	.probe  = sfctemp_probe,
> +	.remove = sfctemp_remove,
> +};
> +module_platform_driver(sfctemp_driver);
> +
> +MODULE_AUTHOR("Emil Renner Berthing");
> +MODULE_DESCRIPTION("StarFive JH7100 temperature sensor driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.32.0
> 

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