Re: [PATCH v2 12/16] hwmon: add support for the sl28cpld hardware monitoring controller

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On Thu, Apr 02, 2020 at 10:36:52PM +0200, Michael Walle wrote:
> This adds support for the hardware monitoring controller of the sl28cpld
> board management controller. This driver is part of a multi-function
> device.
> 
> Signed-off-by: Michael Walle <michael@xxxxxxxx>
> ---
>  Documentation/hwmon/sl28cpld.rst |  36 ++++++++

Needs to be added to Documentation.hwmon/index.rst.
Otherwise looks good. With that fixed, please feel free to add

Acked-by: Guenter Roeck <linux@xxxxxxxxxxxx>

in the next version.

Guenter

>  drivers/hwmon/Kconfig            |  10 ++
>  drivers/hwmon/Makefile           |   1 +
>  drivers/hwmon/sl28cpld-hwmon.c   | 151 +++++++++++++++++++++++++++++++
>  4 files changed, 198 insertions(+)
>  create mode 100644 Documentation/hwmon/sl28cpld.rst
>  create mode 100644 drivers/hwmon/sl28cpld-hwmon.c
> 
> diff --git a/Documentation/hwmon/sl28cpld.rst b/Documentation/hwmon/sl28cpld.rst
> new file mode 100644
> index 000000000000..7ed65f78250c
> --- /dev/null
> +++ b/Documentation/hwmon/sl28cpld.rst
> @@ -0,0 +1,36 @@
> +.. SPDX-License-Identifier: GPL-2.0-only
> +
> +Kernel driver sl28cpld
> +======================
> +
> +Supported chips:
> +
> +   * Kontron sl28cpld
> +
> +     Prefix: 'sl28cpld'
> +
> +     Datasheet: not available
> +
> +Authors: Michael Walle <michael@xxxxxxxx>
> +
> +Description
> +-----------
> +
> +The sl28cpld is a board management controller which also exposes a hardware
> +monitoring controller. At the moment this controller supports a single fan
> +supervisor. In the future there might be other flavours and additional
> +hardware monitoring might be supported.
> +
> +The fan supervisor has a 7 bit counter register and a counter period of 1
> +second. If the 7 bit counter overflows, the supervisor will automatically
> +switch to x8 mode to support a wider input range at the loss of
> +granularity.
> +
> +Sysfs entries
> +-------------
> +
> +The following attributes are supported.
> +
> +======================= ========================================================
> +fan1_input		Fan RPM. Assuming 2 pulses per revolution.
> +======================= ========================================================
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 05a30832c6ba..c98716f78cfa 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1412,6 +1412,16 @@ config SENSORS_RASPBERRYPI_HWMON
>  	  This driver can also be built as a module. If so, the module
>  	  will be called raspberrypi-hwmon.
>  
> +config SENSORS_SL28CPLD
> +	tristate "Kontron's SMARC-sAL28 hardware monitoring driver"
> +	depends on MFD_SL28CPLD
> +	help
> +	  If you say yes here you get support for a fan connected to the
> +	  input of the SMARC connector of Kontron's SMARC-sAL28 module.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called sl28cpld-hwmon.
> +
>  config SENSORS_SHT15
>  	tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
>  	depends on GPIOLIB || COMPILE_TEST
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index b0b9c8e57176..dfb0f8cda2dd 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -155,6 +155,7 @@ obj-$(CONFIG_SENSORS_S3C)	+= s3c-hwmon.o
>  obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
>  obj-$(CONFIG_SENSORS_SCH5627)	+= sch5627.o
>  obj-$(CONFIG_SENSORS_SCH5636)	+= sch5636.o
> +obj-$(CONFIG_SENSORS_SL28CPLD)	+= sl28cpld-hwmon.o
>  obj-$(CONFIG_SENSORS_SHT15)	+= sht15.o
>  obj-$(CONFIG_SENSORS_SHT21)	+= sht21.o
>  obj-$(CONFIG_SENSORS_SHT3x)	+= sht3x.o
> diff --git a/drivers/hwmon/sl28cpld-hwmon.c b/drivers/hwmon/sl28cpld-hwmon.c
> new file mode 100644
> index 000000000000..c79bdfed8332
> --- /dev/null
> +++ b/drivers/hwmon/sl28cpld-hwmon.c
> @@ -0,0 +1,151 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * sl28cpld hardware monitoring driver.
> + *
> + * Copyright 2019 Kontron Europe GmbH
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/hwmon.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#define FAN_INPUT		0x00
> +#define   FAN_SCALE_X8		BIT(7)
> +#define   FAN_VALUE_MASK	GENMASK(6, 0)
> +
> +struct sl28cpld_hwmon {
> +	struct regmap *regmap;
> +	u32 offset;
> +};
> +
> +static umode_t sl28cpld_hwmon_is_visible(const void *data,
> +					 enum hwmon_sensor_types type,
> +					 u32 attr, int channel)
> +{
> +	return 0444;
> +}
> +
> +static int sl28cpld_hwmon_read(struct device *dev,
> +			       enum hwmon_sensor_types type, u32 attr,
> +			       int channel, long *input)
> +{
> +	struct sl28cpld_hwmon *hwmon = dev_get_drvdata(dev);
> +	unsigned int value;
> +	int ret;
> +
> +	switch (attr) {
> +	case hwmon_fan_input:
> +		ret = regmap_read(hwmon->regmap, hwmon->offset + FAN_INPUT,
> +				  &value);
> +		if (ret)
> +			return ret;
> +		/*
> +		 * The register has a 7 bit value and 1 bit which indicates the
> +		 * scale. If the MSB is set, then the lower 7 bit has to be
> +		 * multiplied by 8, to get the correct reading.
> +		 */
> +		if (value & FAN_SCALE_X8)
> +			value = FIELD_GET(FAN_VALUE_MASK, value) << 3;
> +
> +		/*
> +		 * The counter period is 1000ms and the sysfs specification
> +		 * says we should asssume 2 pulses per revolution.
> +		 */
> +		value *= 60 / 2;
> +
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	*input = value;
> +	return 0;
> +}
> +
> +static const u32 sl28cpld_hwmon_fan_config[] = {
> +	HWMON_F_INPUT,
> +	0
> +};
> +
> +static const struct hwmon_channel_info sl28cpld_hwmon_fan = {
> +	.type = hwmon_fan,
> +	.config = sl28cpld_hwmon_fan_config,
> +};
> +
> +static const struct hwmon_channel_info *sl28cpld_hwmon_info[] = {
> +	&sl28cpld_hwmon_fan,
> +	NULL
> +};
> +
> +static const struct hwmon_ops sl28cpld_hwmon_ops = {
> +	.is_visible = sl28cpld_hwmon_is_visible,
> +	.read = sl28cpld_hwmon_read,
> +};
> +
> +static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = {
> +	.ops = &sl28cpld_hwmon_ops,
> +	.info = sl28cpld_hwmon_info,
> +};
> +
> +static int sl28cpld_hwmon_probe(struct platform_device *pdev)
> +{
> +	struct device *hwmon_dev;
> +	struct sl28cpld_hwmon *hwmon;
> +	struct resource *res;
> +
> +	if (!pdev->dev.parent)
> +		return -ENODEV;
> +
> +	hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
> +	if (!hwmon)
> +		return -ENOMEM;
> +
> +	hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!hwmon->regmap)
> +		return -ENODEV;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_REG, 0);
> +	if (!res)
> +		return -EINVAL;
> +	hwmon->offset = res->start;
> +
> +	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
> +				"sl28cpld_hwmon", hwmon,
> +				&sl28cpld_hwmon_chip_info, NULL);
> +	if (IS_ERR(hwmon_dev)) {
> +		dev_err(&pdev->dev, "failed to register as hwmon device");
> +		return PTR_ERR(hwmon_dev);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id sl28cpld_hwmon_of_match[] = {
> +	{ .compatible = "kontron,sl28cpld-fan" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match);
> +
> +static const struct platform_device_id sl28cpld_hwmon_id_table[] = {
> +	{ "sl28cpld-fan" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(platform, sl28cpld_hwmon_id_table);
> +
> +static struct platform_driver sl28cpld_hwmon_driver = {
> +	.probe = sl28cpld_hwmon_probe,
> +	.id_table = sl28cpld_hwmon_id_table,
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +		.of_match_table = sl28cpld_hwmon_of_match,
> +	},
> +};
> +module_platform_driver(sl28cpld_hwmon_driver);
> +
> +MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver");
> +MODULE_AUTHOR("Michael Walle <michael@xxxxxxxx>");
> +MODULE_LICENSE("GPL");