Re: [PATCH v7 3/6] hwmon: sy7636a: Add temperature driver for sy7636a

From: Lee Jones
Date: Tue Jul 20 2021 - 11:17:03 EST


On Thu, 08 Jul 2021, Alistair Francis wrote:

> This is a multi-function device to interface with the sy7636a
> EPD PMIC chip from Silergy.
>
> Signed-off-by: Alistair Francis <alistair@xxxxxxxxxxxxx>
> ---
> arch/arm/configs/imx_v6_v7_defconfig | 1 +
> drivers/hwmon/Kconfig | 10 +++
> drivers/hwmon/Makefile | 1 +
> drivers/hwmon/sy7636a-hwmon.c | 106 +++++++++++++++++++++++++++
> 4 files changed, 118 insertions(+)
> create mode 100644 drivers/hwmon/sy7636a-hwmon.c
>
> diff --git a/arch/arm/configs/imx_v6_v7_defconfig b/arch/arm/configs/imx_v6_v7_defconfig
> index cd80e85d37cf..e9c0be5629c6 100644
> --- a/arch/arm/configs/imx_v6_v7_defconfig
> +++ b/arch/arm/configs/imx_v6_v7_defconfig
> @@ -227,6 +227,7 @@ CONFIG_RN5T618_POWER=m
> CONFIG_SENSORS_MC13783_ADC=y
> CONFIG_SENSORS_GPIO_FAN=y
> CONFIG_SENSORS_IIO_HWMON=y
> +CONFIG_SENSORS_SY7636A=y
> CONFIG_THERMAL_STATISTICS=y
> CONFIG_THERMAL_WRITABLE_TRIPS=y
> CONFIG_CPU_THERMAL=y
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index e3675377bc5d..6cae12de59cd 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1631,6 +1631,16 @@ config SENSORS_SIS5595
> This driver can also be built as a module. If so, the module
> will be called sis5595.
>
> +config SENSORS_SY7636A
> + tristate "Silergy SY7636A"
> + depends on I2C
> + help
> + If you say yes here you get support for the thermistor readout of
> + the Silergy SY7636A PMIC.
> +
> + This driver can also be built as a module. If so, the module
> + will be called sy7636a-hwmon.
> +
> config SENSORS_DME1737
> tristate "SMSC DME1737, SCH311x and compatibles"
> depends on I2C && !PPC
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index d712c61c1f5e..8b2e09e25b24 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -180,6 +180,7 @@ obj-$(CONFIG_SENSORS_SMSC47M1) += smsc47m1.o
> obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
> obj-$(CONFIG_SENSORS_SPARX5) += sparx5-temp.o
> obj-$(CONFIG_SENSORS_STTS751) += stts751.o
> +obj-$(CONFIG_SENSORS_SY7636A) += sy7636a-hwmon.o
> obj-$(CONFIG_SENSORS_AMC6821) += amc6821.o
> obj-$(CONFIG_SENSORS_TC74) += tc74.o
> obj-$(CONFIG_SENSORS_THMC50) += thmc50.o
> diff --git a/drivers/hwmon/sy7636a-hwmon.c b/drivers/hwmon/sy7636a-hwmon.c
> new file mode 100644
> index 000000000000..4edbee99b693
> --- /dev/null
> +++ b/drivers/hwmon/sy7636a-hwmon.c
> @@ -0,0 +1,106 @@
> +/*
> + * Functions to access SY3686A power management chip temperature
> + *
> + * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/
> + *
> + * Author: Lars Ivar Miljeteig <lars.ivar.miljeteig@xxxxxxxxxxxxxx>
> + *
> + * 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.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.

The long form isn't usually accepted anymore.

Please replace with SPDX.

> + */
> +
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/jiffies.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/err.h>
> +#include <linux/sysfs.h>
> +#include <linux/platform_device.h>
> +
> +#include <linux/mfd/sy7636a.h>
> +
> +struct sy7636a_data {
> + struct sy7636a *sy7636a;
> + struct device *hwmon_dev;
> +};
> +
> +static ssize_t show_temp(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + unsigned int reg_val;
> + signed char temp;
> + int ret;
> + struct sy7636a_data *data = dev_get_drvdata(dev);
> +
> + ret = regmap_read(data->sy7636a->regmap,
> + SY7636A_REG_TERMISTOR_READOUT, &reg_val);
> + if (ret)
> + return ret;
> +
> + temp = *((signed char*)&reg_val);

Whoa! What's going on here?

You also need to run checkpatch.pl.

> + return snprintf(buf, PAGE_SIZE, "%d\n", temp);
> +}
> +
> +static SENSOR_DEVICE_ATTR(temp0, S_IRUGO, show_temp, NULL, 0);
> +
> +static struct attribute *sy7636a_attrs[] = {
> + &sensor_dev_attr_temp0.dev_attr.attr,
> + NULL
> +};
> +
> +ATTRIBUTE_GROUPS(sy7636a);
> +
> +static int sy7636a_sensor_probe(struct platform_device *pdev)
> +{
> + struct sy7636a *sy7636a = dev_get_drvdata(pdev->dev.parent);
> + struct sy7636a_data *data;
> + int err;
> +
> + if (!sy7636a)
> + return -EPROBE_DEFER;
> +
> + data = devm_kzalloc(&pdev->dev, sizeof(struct sy7636a_data), GFP_KERNEL);

Where is this used, outside of this function?

Not sure I see a good reason for having it around?

> + if (!data) {
> + return -ENOMEM;
> + }
> +
> + data->sy7636a = sy7636a;
> + data->hwmon_dev = devm_hwmon_device_register_with_groups(&pdev->dev,

Why is this being stored into a struct?

> + "sy7636a_temperature", data, sy7636a_groups);
> + if (IS_ERR(data->hwmon_dev)) {
> + err = PTR_ERR(data->hwmon_dev);
> + dev_err(&pdev->dev, "Unable to register hwmon device, returned %d", err);
> + return err;
> + }
> +
> + return 0;
> +}
> +
> +static const struct platform_device_id sy7636a_sensor_id[] = {
> + { "sy7636a-temperature", 0},
> + { },
> +};
> +MODULE_DEVICE_TABLE(platform, sy7636a_sensor_id);
> +
> +static struct platform_driver sy7636a_sensor_driver = {
> + .probe = sy7636a_sensor_probe,
> + .id_table = sy7636a_sensor_id,

What does this do?

Where is the 'device' being registered?

> + .driver = {
> + .name = "sy7636a-temperature",
> + },
> +};
> +module_platform_driver(sy7636a_sensor_driver);
> +
> +MODULE_DESCRIPTION("SY7636A sensor driver");
> +MODULE_LICENSE("GPL");
> +

--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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