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>

1 files 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,