[PATCH v1 08/10] pwm: atmel-tcb: Support backup mode

Romain Izard
2017-09-08T15:36:34Z

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>
---
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