linux-kernel - Re: [PATCH v9 2/4] power: reset: add reboot mode driver

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Message-id: <5767A4C0.3080902@samsung.com>
Date:	Mon, 20 Jun 2016 10:09:36 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Andy Yan <andy.yan@...k-chips.com>, robh+dt@...nel.org,
	heiko@...ech.de, john.stultz@...aro.org, arnd@...db.de,
	bjorn.andersson@...aro.org
Cc:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	alexandre.belloni@...e-electrons.com, dbaryshkov@...il.com,
	sre@...nel.org, matthias.bgg@...il.com, linux-pm@...r.kernel.org,
	mbrugger@...e.com, lorenzo.pieralisi@....com,
	moritz.fischer@...us.com, richard@....at
Subject: Re: [PATCH v9 2/4] power: reset: add reboot mode driver

On 06/20/2016 08:38 AM, Andy Yan wrote:
> This driver parses the reboot commands like "reboot bootloader"
> and "reboot recovery" to get a boot mode described in the
> device tree , then call the write interfae to store the boot
> mode in some place like special register or sram, which can
> be read by the bootloader after system reboot, then the bootloader
> can take different action according to the mode stored.
> 
> This is commonly used on Android based devices, in order to
> reboot the device into fastboot or recovery mode.
> 
> Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>
> Reviewed-by: Moritz Fischer <moritz.fischer@...us.com>
> Tested-by: John Stultz <john.stultz@...aro.org>
> Acked-by: John Stultz <john.stultz@...aro.org>
> Signed-off-by: Andy Yan <andy.yan@...k-chips.com>
> 
> ---
> 
> Changes in v9:
> - select MFD_SYSCON when syscon-reboot-mode driver enabled
> - refactoring error handling in reboot_mode_register
> 
> Changes in v8:
> - do some cleanup when driver ubind
> 
> Changes in v7:
> - address some suggestions from Krzysztof, make syscon-reboot-mode driver data self-contained.
> 
> Changes in v6: None
> Changes in v5:
> - use two blank space under help in Kconfig
> - use unsigned int instead of int for member magic in struct mode_info
> 
> Changes in v4:
> - make this driver depends on OF to avoid kbuild test error
> 
> Changes in v3:
> - scan multi properities
> - add mask value for some platform which only use some bits of the register
>   to store boot mode magic value
> 
> Changes in v2:
> - move to dir drivers/power/reset/
> - make syscon-reboot-mode a generic driver
> 
> Changes in v1:
> - fix the embarrassed compile warning
> - correct the maskrom magic number
> - check for the normal reboot
> 
>  drivers/power/reset/Kconfig              |  14 ++++
>  drivers/power/reset/Makefile             |   2 +
>  drivers/power/reset/reboot-mode.c        | 128 +++++++++++++++++++++++++++++++
>  drivers/power/reset/reboot-mode.h        |  14 ++++
>  drivers/power/reset/syscon-reboot-mode.c | 100 ++++++++++++++++++++++++
>  5 files changed, 258 insertions(+)
>  create mode 100644 drivers/power/reset/reboot-mode.c
>  create mode 100644 drivers/power/reset/reboot-mode.h
>  create mode 100644 drivers/power/reset/syscon-reboot-mode.c
> 
> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> index 9bb2622..4ceaf74 100644
> --- a/drivers/power/reset/Kconfig
> +++ b/drivers/power/reset/Kconfig
> @@ -183,5 +183,19 @@ config POWER_RESET_ZX
>  	help
>  	  Reboot support for ZTE SoCs.
>  
> +config REBOOT_MODE
> +	tristate
> +
> +config SYSCON_REBOOT_MODE
> +	bool "Generic SYSCON regmap reboot mode driver"

Why not tristate?

Beside that the patch looks good.

Best regards,
Krzysztof

> +	depends on OF
> +	select REBOOT_MODE
> +	select MFD_SYSCON
> +	help
> +	  Say y here will enable reboot mode driver. This will
> +	  get reboot mode arguments and store it in SYSCON mapped
> +	  register, then the bootloader can read it to take different
> +	  action according to the mode.
> +