Re: [PATCH v9 2/3] mfd: add Gateworks System Controller core driver

[Lee Jones <lee.jones@linaro.org>]

On Thu, 30 Apr 2020, Tim Harvey wrote:

> The Gateworks System Controller (GSC) is an I2C slave controller
> implemented with an MSP430 micro-controller whose firmware embeds the
> following features:
>  - I/O expander (16 GPIO's) using PCA955x protocol
>  - Real Time Clock using DS1672 protocol
>  - User EEPROM using AT24 protocol
>  - HWMON using custom protocol
>  - Interrupt controller with tamper detect, user pushbotton
>  - Watchdog controller capable of full board power-cycle
>  - Power Control capable of full board power-cycle
> 
> see http://trac.gateworks.com/wiki/gsc for more details
> 
> Signed-off-by: Tim Harvey <tharvey@gateworks.com>
> ---
> v9:
> - rebase against 5.7-rc2
> - cleanup gsc_powerdown() by using BIT(), put_unaligned_le32(), and avoid
>   unnecessary assignments
> - rename GSC_CTRL_1 SLEEP related defines to simplify
> - add better description and sub-module info to driver description
> - whitespace changes per review
> - remove unused irq_data pointer in ddata
> - remove unnecesary i2c_set_clientdata
> - use devm_i2c_new_dummy_device to avoid need of free's
> - change regsiter definitions to enum
> - export gsc_{read,write} instead of sharing them via ddata
> 
> v8:
> - whitespace fixes
> - describe sub-devices in Kconfig
> - add error print for invalid command
> - update copyright
> - use devm_of_platform_populate
> - use probe_new
> - move hwmon's regmap init to hwmon
> 
> v7:
> - remove irq from private data struct
> 
> v6:
> - remove duplicate signature and fix commit log
> 
> v5:
> - simplify powerdown function
> 
> v4:
> - remove hwmon max reg check/define
> - fix powerdown function
> 
> v3:
> - rename gsc->gateworks-gsc
> - remove uncecessary include for linux/mfd/core.h
> - upercase I2C in comments
> - remove i2c debug
> - remove uncecessary comments
> - don't use KBUILD_MODNAME for name
> - remove unnecessary v1/v2/v3 tracking
> - unregister hwmon i2c adapter on remove
> 
> v2:
> - change license comment block style
> - remove COMPILE_TEST (Randy)
> - fixed whitespace issues
> - replaced a printk with dev_err
> ---
>  MAINTAINERS                 |   8 ++
>  drivers/mfd/Kconfig         |  16 +++
>  drivers/mfd/Makefile        |   1 +
>  drivers/mfd/gateworks-gsc.c | 284 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/gsc.h     |  76 ++++++++++++
>  5 files changed, 385 insertions(+)
>  create mode 100644 drivers/mfd/gateworks-gsc.c
>  create mode 100644 include/linux/mfd/gsc.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b816a45..035dfb9 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7032,6 +7032,14 @@ F:	kernel/futex.c
>  F:	tools/perf/bench/futex*
>  F:	tools/testing/selftests/futex/
>  
> +GATEWORKS SYSTEM CONTROLLER (GSC) DRIVER
> +M:	Tim Harvey <tharvey@gateworks.com>
> +M:	Robert Jones <rjones@gateworks.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/mfd/gateworks-gsc.yaml
> +F:	drivers/mfd/gateworks-gsc.c
> +F:	include/linux/mfd/gsc.h
> +
>  GASKET DRIVER FRAMEWORK
>  M:	Rob Springer <rspringer@google.com>
>  M:	Todd Poynor <toddpoynor@google.com>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 0a59249..d7546cd 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -407,6 +407,22 @@ config MFD_EXYNOS_LPASS
>  	  Select this option to enable support for Samsung Exynos Low Power
>  	  Audio Subsystem.
>  
> +config MFD_GATEWORKS_GSC
> +	tristate "Gateworks System Controller"
> +	depends on (I2C && OF)
> +	select MFD_CORE
> +	select REGMAP_I2C
> +	select REGMAP_IRQ
> +	help
> +	  Enable support for the Gateworks System Controller (GSC) found
> +	  on Gateworks Single Board Computers supporting system system

"system"

> +	  functions such as pushbutton monitor, multiple ADC's for voltage

"push-button"

> +	  and temperature, fan controller, and watchdog monitor. This

"voltage and temperature" what?

Monitoring, adjusting, guessing, mixing, matching?

I'd drop the pre-and comma myself.

> +	  driver provides common support for accessing the device and

Turn the "and" into a full-stop.

> +	  additional drivers must be enabled in order to use the
> +	  functionality of the device:
> +		gsc-hwmon for ADC readings and fan controller support

What does this line represent?  Is it an example?

>  config MFD_MC13XXX
>  	tristate
>  	depends on (SPI_MASTER || I2C)
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index f935d10..ed433ae 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
>  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
>  obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
>  obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
> +obj-$(CONFIG_MFD_GATEWORKS_GSC)	+= gateworks-gsc.o
>  
>  obj-$(CONFIG_HTC_PASIC3)	+= htc-pasic3.o
>  obj-$(CONFIG_HTC_I2CPLD)	+= htc-i2cpld.o
> diff --git a/drivers/mfd/gateworks-gsc.c b/drivers/mfd/gateworks-gsc.c
> new file mode 100644
> index 00000000..796effb
> --- /dev/null
> +++ b/drivers/mfd/gateworks-gsc.c
> @@ -0,0 +1,284 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * The Gateworks System Controller (GSC) is a multi-function
> + * device designed for use in Gateworks Single Board Computers.
> + * The control interface is I2C, with an interrupt. The device supports
> + * system functions such as pushbutton monitoring, multiple ADC's for
> + * voltage and temperature, fan controller, and watchdog monitor.

As above.

> + * Copyright (C) 2020 Gateworks Corporation
> + */
> +
> +#include <linux/device.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/gsc.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include <asm/unaligned.h>

[...]

> +static const struct i2c_device_id gsc_id_table[] = {
> +	{ "gsc", GSC_MISC },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, gsc_id_table);

Using probe_new means you can omit this unused table.

Once all of the above has been fixed, please add my:


For my own reference (apply this as-is to your sign-off block):

  Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>

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