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SubjectRe: [PATCH 14/18] hwmon: add support for the sl28cpld hardware monitoring controller
Hi Guenter,

thanks for the review

Am 2020-03-18 04:27, schrieb Guenter Roeck:
> On 3/17/20 1:50 PM, 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@walle.cc>
>> ---
>> drivers/hwmon/Kconfig | 10 +++
>> drivers/hwmon/Makefile | 1 +
>> drivers/hwmon/sl28cpld-hwmon.c | 146
>> +++++++++++++++++++++++++++++++++
>
> Please also provide Documentation/hwmon/sl28cpld.
>
>> 3 files changed, 157 insertions(+)
>> create mode 100644 drivers/hwmon/sl28cpld-hwmon.c
>>
>> 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..7ac42bb0a48c
>> --- /dev/null
>> +++ b/drivers/hwmon/sl28cpld-hwmon.c
>> @@ -0,0 +1,146 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * SMARC-sAL28 fan hardware monitoring driver.
>> + *
>> + * Copyright 2019 Kontron Europe GmbH
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/bitfield.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_address.h>
>> +#include <linux/regmap.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/hwmon.h>
>> +
> Alphabetic order of include files, please.

ok, I guess that applies to all of the new files.


>> +#define FAN_INPUT 0
>> +#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;
>> +
>> + hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
>> + if (!hwmon)
>> + return -ENOMEM;
>> +
>> + if (!pdev->dev.parent)
>> + return -ENODEV;
>> +
> Maybe do this first ?

ok. like explained on another patch review comment, I had that
together with the following dev_get_regmap() which uses this.
But I was already not sure while writing the code whether I
should do it first and don't have to undo the devm_ in case of
an error. Well since already two reviewers stumbled on this,
I'll do it first on all the patches.


>> + 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 platform_device_id sl28cpld_hwmon_id_table[] = {
>> + {"sl28cpld-fan", 0},
>> +};
>> +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,
>
> I'd have expected an of_match_table.

There was one, but, since I use mfd_add_devices() which uses the
platform driver name (or the id_table) I removed it. While it
doesn't really matter here in the hwmon part for now, the GPIO
driver uses the id_table data to distinguish between different
flavors of the GPIO controller. So there I'd have to duplicate
data in the tables (eg. the id_table as well as the
of_match_table) and get that data in the _probe(), although only
the id_table data is used.

-michael

>
>> + .driver = {
>> + .name = "sl28cpld-hwmon",
>> + },
>> +};
>> +module_platform_driver(sl28cpld_hwmon_driver);
>> +
>> +MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver");
>> +MODULE_LICENSE("GPL");
>>

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