linux-kernel - Re: [PATCH v2 7/9] pwm: atmel-tcb: Support backup mode

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Date:   Fri, 22 Sep 2017 14:42:37 +0200
From:   Nicolas Ferre <nicolas.ferre@...rochip.com>
To:     Romain Izard <romain.izard.pro@...il.com>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Wenyou Yang <wenyou.yang@...el.com>,
        Josh Wu <rainyfeeling@...look.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        Thierry Reding <thierry.reding@...il.com>,
        Richard Genoud <richard.genoud@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>
CC:     <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mtd@...ts.infradead.org>, <linux-pwm@...r.kernel.org>,
        <linux-serial@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 7/9] pwm: atmel-tcb: Support backup mode

On 15/09/2017 at 16:04, Romain Izard wrote:
> Save and restore registers for the PWM on suspend and resume, which
> makes hibernation and backup modes possible.
> 
> Signed-off-by: Romain Izard <romain.izard.pro@...il.com>

Seems good to me:
Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>

> ---
>  drivers/pwm/pwm-atmel-tcb.c | 63 +++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 61 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-atmel-tcb.c b/drivers/pwm/pwm-atmel-tcb.c
> index 75db585a2a94..acd3ce8ecf3f 100644
> --- a/drivers/pwm/pwm-atmel-tcb.c
> +++ b/drivers/pwm/pwm-atmel-tcb.c
> @@ -37,11 +37,20 @@ struct atmel_tcb_pwm_device {
>  	unsigned period;		/* PWM period expressed in clk cycles */
>  };
>  
> +struct atmel_tcb_channel {
> +	u32 enabled;
> +	u32 cmr;
> +	u32 ra;
> +	u32 rb;
> +	u32 rc;
> +};
> +
>  struct atmel_tcb_pwm_chip {
>  	struct pwm_chip chip;
>  	spinlock_t lock;
>  	struct atmel_tc *tc;
>  	struct atmel_tcb_pwm_device *pwms[NPWM];
> +	struct atmel_tcb_channel bkup[NPWM / 2];
>  };
>  
>  static inline struct atmel_tcb_pwm_chip *to_tcb_chip(struct pwm_chip *chip)
> @@ -175,12 +184,15 @@ static void atmel_tcb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>  	 * Use software trigger to apply the new setting.
>  	 * If both PWM devices in this group are disabled we stop the clock.
>  	 */
> -	if (!(cmr & (ATMEL_TC_ACPC | ATMEL_TC_BCPC)))
> +	if (!(cmr & (ATMEL_TC_ACPC | ATMEL_TC_BCPC))) {
>  		__raw_writel(ATMEL_TC_SWTRG | ATMEL_TC_CLKDIS,
>  			     regs + ATMEL_TC_REG(group, CCR));
> -	else
> +		tcbpwmc->bkup[group].enabled = 1;
> +	} else {
>  		__raw_writel(ATMEL_TC_SWTRG, regs +
>  			     ATMEL_TC_REG(group, CCR));
> +		tcbpwmc->bkup[group].enabled = 0;
> +	}
>  
>  	spin_unlock(&tcbpwmc->lock);
>  }
> @@ -263,6 +275,7 @@ static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>  	/* Use software trigger to apply the new setting */
>  	__raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
>  		     regs + ATMEL_TC_REG(group, CCR));
> +	tcbpwmc->bkup[group].enabled = 1;
>  	spin_unlock(&tcbpwmc->lock);
>  	return 0;
>  }
> @@ -445,10 +458,56 @@ static const struct of_device_id atmel_tcb_pwm_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, atmel_tcb_pwm_dt_ids);
>  
> +#ifdef CONFIG_PM_SLEEP
> +static int atmel_tcb_pwm_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct atmel_tcb_pwm_chip *tcbpwm = platform_get_drvdata(pdev);
> +	void __iomem *base = tcbpwm->tc->regs;
> +	int i;
> +
> +	for (i = 0; i < (NPWM / 2); i++) {
> +		struct atmel_tcb_channel *chan = &tcbpwm->bkup[i];
> +
> +		chan->cmr = readl(base + ATMEL_TC_REG(i, CMR));
> +		chan->ra = readl(base + ATMEL_TC_REG(i, RA));
> +		chan->rb = readl(base + ATMEL_TC_REG(i, RB));
> +		chan->rc = readl(base + ATMEL_TC_REG(i, RC));
> +	}
> +	return 0;
> +}
> +
> +static int atmel_tcb_pwm_resume(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct atmel_tcb_pwm_chip *tcbpwm = platform_get_drvdata(pdev);
> +	void __iomem *base = tcbpwm->tc->regs;
> +	int i;
> +
> +	for (i = 0; i < (NPWM / 2); i++) {
> +		struct atmel_tcb_channel *chan = &tcbpwm->bkup[i];
> +
> +		writel(chan->cmr, base + ATMEL_TC_REG(i, CMR));
> +		writel(chan->ra, base + ATMEL_TC_REG(i, RA));
> +		writel(chan->rb, base + ATMEL_TC_REG(i, RB));
> +		writel(chan->rc, base + ATMEL_TC_REG(i, RC));
> +		if (chan->enabled) {
> +			writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
> +				base + ATMEL_TC_REG(i, CCR));
> +		}
> +	}
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(atmel_tcb_pwm_pm_ops, atmel_tcb_pwm_suspend,
> +			 atmel_tcb_pwm_resume);
> +
>  static struct platform_driver atmel_tcb_pwm_driver = {
>  	.driver = {
>  		.name = "atmel-tcb-pwm",
>  		.of_match_table = atmel_tcb_pwm_dt_ids,
> +		.pm = &atmel_tcb_pwm_pm_ops,
>  	},
>  	.probe = atmel_tcb_pwm_probe,
>  	.remove = atmel_tcb_pwm_remove,
> 


-- 
Nicolas Ferre