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@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-atmel-tcb.c b/drivers/pwm/pwm-atmel-tcb.c
index 75db585..acd3ce8 100644 (file)
--- 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,