Re: [PATCH v6 3/3] hwmon: add Gateworks System Controller support

[Guenter Roeck <linux@roeck-us.net>]

On 3/17/20 10:00 AM, Tim Harvey wrote:
> The Gateworks System Controller has a hwmon sub-component that exposes
> up to 16 ADC's, some of which are temperature sensors, others which are
> voltage inputs. The ADC configuration (register mapping and name) is
> configured via device-tree and varies board to board.
> 
> Cc: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Tim Harvey <tharvey@gateworks.com>
> ---
> v6:
> - fix size of info field
> - improve pwm output control documentation
> - include unit suffix in divider and offset
> - change adc subnode name to gsc-adc
> - change fan base to fan subnode
> - change adc type to mode
> - fix voltage offset scaling
> 
> v5:
> - fix various checkpatch issues
> - correct gsc-hwmon.rst in MAINTAINERS
> - encorporate Gunter's feedback:
>  - switch to SENSOR_DEVICE_ATTR_{RW,RO}
>  - use tmp value to avoid excessive pointer deference
>  - simplify shift operation
>  - scale voffset once
>  - simplify is_visible function
>  - remove empty line at end of file
> 
> v4:
> - adjust for uV offset from device-tree
> - remove unnecessary optional write function
> - remove register range check
> - change dev_err prints to use gsc dev
> - hard-code resolution/scaling for raw adcs
> - describe units of ADC resolution
> - move to using pwm<n>_auto_point<m>_{pwm,temp} for FAN PWM
> - ensure space before/after operators
> - remove unnecessary parens
> - remove more debugging
> - add default case and comment for type_voltage
> - remove unnecessary index bounds checks for channel
> - remove unnecessary clearing of struct fields
> - added Documentation/hwmon/gsc-hwmon.rst
> 
> v3:
> - add voltage_raw input type and supporting fields
> - add channel validation to is_visible function
> - remove unnecessary channel validation from read/write functions
> 
> v2:
> - change license comment style
> - remove DEBUG
> - simplify regmap_bulk_read err check
> - remove break after returns in switch statement
> - fix fan setpoint buffer address
> - remove unnecessary parens
> - consistently use struct device *dev pointer
> - change license/comment block
> - add validation for hwmon child node props
> - move parsing of of to own function
> - use strlcpy to ensure null termination
> - fix static array sizes and removed unnecessary initializers
> - dynamically allocate channels
> - fix fan input label
> - support platform data
> - fixed whitespace issues
> ---
>  Documentation/hwmon/gsc-hwmon.rst       |  53 +++++
>  Documentation/hwmon/index.rst           |   1 +
>  MAINTAINERS                             |   3 +
>  drivers/hwmon/Kconfig                   |   9 +
>  drivers/hwmon/Makefile                  |   1 +
>  drivers/hwmon/gsc-hwmon.c               | 372 ++++++++++++++++++++++++++++++++
>  include/linux/platform_data/gsc_hwmon.h |  44 ++++
>  7 files changed, 483 insertions(+)
>  create mode 100644 Documentation/hwmon/gsc-hwmon.rst
>  create mode 100644 drivers/hwmon/gsc-hwmon.c
>  create mode 100644 include/linux/platform_data/gsc_hwmon.h
> 
> diff --git a/Documentation/hwmon/gsc-hwmon.rst b/Documentation/hwmon/gsc-hwmon.rst
> new file mode 100644
> index 00000000..ffac392
> --- /dev/null
> +++ b/Documentation/hwmon/gsc-hwmon.rst
> @@ -0,0 +1,53 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver gsc-hwmon
> +=======================
> +
> +Supported chips: Gateworks GSC
> +Datasheet: http://trac.gateworks.com/wiki/gsc
> +Author: Tim Harvey <tharvey@gateworks.com>
> +
> +Description:
> +------------
> +
> +This driver supports hardware monitoring for the temperature sensor,
> +various ADC's connected to the GSC, and optional FAN controller available
> +on some boards.
> +
> +
> +Voltage Monitoring
> +------------------
> +
> +The voltage inputs are scaled either internally or by the driver depending
> +on the GSC version and firmware. The values returned by the driver do not need
> +further scaling. The voltage input labels provide the voltage rail name:
> +
> +inX_input                  Measured voltage (mV).
> +inX_label                  Name of voltage rail.
> +
> +
> +Temperature Monitoring
> +----------------------
> +
> +Temperatures are measured with 12-bit or 10-bit resolution and are scaled
> +either internally or by the driver depending on the GSC version and firmware.
> +The values returned by the driver reflect millidegree Celcius:
> +
> +tempX_input                Measured temperature.
> +tempX_label                Name of temperature input.
> +
> +
> +PWM Output Control
> +------------------
> +
> +The GSC features 1 PWM output that operates in automatic mode where the
> +PWM value will be scalled depending on 6 temperature boundaries.
> +The tempeature boundaries are read-write and in millidegree Celcius and the
> +read-only PWM values range from 0 (off) to 255 (full speed).
> +Fan speed will be set to minimum (off) when the temperature sensor reads
> +less than pwm1_auto_point1_temp and maximum when the temperature sensor
> +equals or exceeds pwm1_auto_point6_temp.
> +
> +pwm1_auto_point[1-6]_pwm       PWM value.
> +pwm1_auto_point[1-6]_temp      Temperature boundary.
> +
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 43cc605..a4fab69 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -58,6 +58,7 @@ Hardware Monitoring Kernel Drivers
>     ftsteutates
>     g760a
>     g762
> +   gsc-hwmon
>     gl518sm
>     hih6130
>     ibmaem
> diff --git a/MAINTAINERS b/MAINTAINERS
> index bb79b60..3f15542 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6846,6 +6846,9 @@ S:	Maintained
>  F:	Documentation/devicetree/bindings/mfd/gateworks-gsc.yaml
>  F:	drivers/mfd/gateworks-gsc.c
>  F:	include/linux/mfd/gsc.h
> +F:	Documentation/hwmon/gsc-hwmon.rst
> +F:	drivers/hwmon/gsc-hwmon.c
> +F:	include/linux/platform_data/gsc_hwmon.h
>  
>  GCC PLUGINS
>  M:	Kees Cook <keescook@chromium.org>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 23dfe84..99dae13 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -494,6 +494,15 @@ config SENSORS_F75375S
>  	  This driver can also be built as a module. If so, the module
>  	  will be called f75375s.
>  
> +config SENSORS_GSC
> +        tristate "Gateworks System Controller ADC"
> +        depends on MFD_GATEWORKS_GSC
> +        help
> +          Support for the Gateworks System Controller A/D converters.
> +
> +	  To compile this driver as a module, choose M here:
> +	  the module will be called gsc-hwmon.
> +
>  config SENSORS_MC13783_ADC
>          tristate "Freescale MC13783/MC13892 ADC"
>          depends on MFD_MC13XXX
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 6db5db9..259cba7 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -71,6 +71,7 @@ obj-$(CONFIG_SENSORS_G760A)	+= g760a.o
>  obj-$(CONFIG_SENSORS_G762)	+= g762.o
>  obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
>  obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
> +obj-$(CONFIG_SENSORS_GSC)	+= gsc-hwmon.o
>  obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
>  obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
>  obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
> diff --git a/drivers/hwmon/gsc-hwmon.c b/drivers/hwmon/gsc-hwmon.c
> new file mode 100644
> index 00000000..c498786
> --- /dev/null
> +++ b/drivers/hwmon/gsc-hwmon.c
> @@ -0,0 +1,372 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for Gateworks System Controller Hardware Monitor module
> + *
> + * Copyright (C) 2020 Gateworks Corporation
> + */
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/mfd/gsc.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +
> +#include <linux/platform_data/gsc_hwmon.h>
> +
> +#define GSC_HWMON_MAX_TEMP_CH	16
> +#define GSC_HWMON_MAX_IN_CH	16
> +
> +#define GSC_HWMON_RESOLUTION	12
> +#define GSC_HWMON_VREF		2500
> +
> +struct gsc_hwmon_data {
> +	struct gsc_dev *gsc;
> +	struct device *dev;

What is 'dev' used for ? I don't think it is necessary.

Guenter