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

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Message-Id: <20170915140411.31716-8-romain.izard.pro@gmail.com>
Date:   Fri, 15 Sep 2017 16:04:09 +0200
From:   Romain Izard <romain.izard.pro@...il.com>
To:     Nicolas Ferre <nicolas.ferre@...rochip.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,
        Romain Izard <romain.izard.pro@...il.com>
Subject: [PATCH v2 7/9] pwm: atmel-tcb: Support backup mode

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>
---
 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,
-- 
2.11.0