linux-kernel - Re: [PATCH v4 2/3] regulator: bd9571mwv: Add support for toggle power switches

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Date:   Tue, 17 Jul 2018 13:49:16 +0200
From:   Niklas Söderlund 
        <niklas.soderlund@...natech.se>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Marek Vasut <marek.vasut+renesas@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        linux-pm@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/3] regulator: bd9571mwv: Add support for toggle
 power switches

Hi Geert,

Thanks for your work.

On 2018-07-16 17:30:51 +0200, Geert Uytterhoeven wrote:
> Extend the existing support for backup mode to toggle power switches.
> With a toggle power switch (or level signal), the following steps must
> be followed exactly:
>    1. Configure PMIC for backup mode, to change the role of the
>       accessory power switch from a power switch to a wake-up switch,
>    2. Switch accessory power switch off, to prepare for system suspend,
>       which is a manual step not controlled by software,
>    3. Suspend system,
>    4. Switch accessory power switch on, to resume the system.
> 
> Hence the PMIC is configured for backup mode when "on" or "1" is written
> to the PMIC's "backup_mode" virtual file in sysfs.  Conversely, writing
> "off" or "0" reverts the role of the accessory switch to a power
> switch.
> 
> Unlike with momentary switches, backup mode is not enabled by default,
> as enabling it prevents the board from being powered off using the power
> switch, which may confuse the user.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>

> ---
> v4:
>   - Improve patch description and comment,
> 
> v3:
>   - Replace use of "wake_up" sysfs file and extra callback for wake-up
>     change notification by custom "backup_mode" sysfs file,
> 
> v2:
>   - Improve patch description,
>   - Drop "return;" at end of function.
> ---
>  drivers/regulator/bd9571mwv-regulator.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/regulator/bd9571mwv-regulator.c b/drivers/regulator/bd9571mwv-regulator.c
> index 1da36a6590c84ba4..c44613b9423baf07 100644
> --- a/drivers/regulator/bd9571mwv-regulator.c
> +++ b/drivers/regulator/bd9571mwv-regulator.c
> @@ -185,6 +185,7 @@ static ssize_t backup_mode_store(struct device *dev,
>  				 const char *buf, size_t count)
>  {
>  	struct bd9571mwv_reg *bdreg = dev_get_drvdata(dev);
> +	unsigned int mode;
>  	int ret;
>  
>  	if (!count)
> @@ -194,6 +195,25 @@ static ssize_t backup_mode_store(struct device *dev,
>  	if (ret)
>  		return ret;
>  
> +	if (!bdreg->rstbmode_level)
> +		return count;
> +
> +	/*
> +	 * Configure DDR Backup Mode, to change the role of the accessory power
> +	 * switch from a power switch to a wake-up switch, or vice versa
> +	 */
> +	ret = bd9571mwv_bkup_mode_read(bdreg->bd, &mode);
> +	if (ret)
> +		return ret;
> +
> +	mode &= ~BD9571MWV_BKUP_MODE_CNT_KEEPON_MASK;
> +	if (bdreg->bkup_mode_enabled)
> +		mode |= bdreg->bkup_mode_cnt_keepon;
> +
> +	ret = bd9571mwv_bkup_mode_write(bdreg->bd, mode);
> +	if (ret)
> +		return ret;
> +
>  	return count;
>  }
>  
> -- 
> 2.17.1
> 

-- 
Regards,
Niklas Söderlund