[PATCH v2 2/3] pwm: pwm-samsung: fix suspend/resume support

[Bartlomiej Zolnierkiewicz]

Fix suspend/resume support:

- add disabled_mask to struct samsung_pwm_chip to track PWM
  disabled state information in pwm_samsung_{disable,enable}()

- rename pwm_samsung_config() to __pwm_samsung_config() and
  add extra force_period parameter to be used during resume
  (to force tin_ns and tcnt recalculation)

- add pwm_samsung_config() wrapper for preserving old behavior

- properly restore PWM configuration in pwm_samsung_resume()

- remove no longer needed pwm_samsung_suspend()

- update Copyrights

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
---
 drivers/pwm/pwm-samsung.c | 67 +++++++++++++++++++++++++----------------------
 1 file changed, 35 insertions(+), 32 deletions(-)

diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c
index 9ea7638..062f2cf 100644
--- a/drivers/pwm/pwm-samsung.c
+++ b/drivers/pwm/pwm-samsung.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2008 Simtec Electronics
  *     Ben Dooks <ben@xxxxxxxxxxxx>, <ben-linux@xxxxxxxxx>
  * Copyright (c) 2013 Tomasz Figa <tomasz.figa@xxxxxxxxx>
+ * Copyright (c) 2017 Samsung Electronics Co., Ltd.
  *
  * PWM driver for Samsung SoCs
  *
@@ -74,6 +75,7 @@ struct samsung_pwm_channel {
  * @chip:		generic PWM chip
  * @variant:		local copy of hardware variant data
  * @inverter_mask:	inverter status for all channels - one bit per channel
+ * @disabled_mask:	disabled status for all channels - one bit per channel
  * @base:		base address of mapped PWM registers
  * @base_clk:		base clock used to drive the timers
  * @tclk0:		external clock 0 (can be ERR_PTR if not present)
@@ -83,6 +85,7 @@ struct samsung_pwm_chip {
 	struct pwm_chip chip;
 	struct samsung_pwm_variant variant;
 	u8 inverter_mask;
+	u8 disabled_mask;
 
 	void __iomem *base;
 	struct clk *base_clk;
@@ -257,6 +260,8 @@ static int pwm_samsung_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	tcon |= TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan);
 	writel(tcon, our_chip->base + REG_TCON);
 
+	our_chip->disabled_mask &= ~BIT(pwm->hwpwm);
+
 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 
 	return 0;
@@ -275,6 +280,8 @@ static void pwm_samsung_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	tcon &= ~TCON_AUTORELOAD(tcon_chan);
 	writel(tcon, our_chip->base + REG_TCON);
 
+	our_chip->disabled_mask |= BIT(pwm->hwpwm);
+
 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }
 
@@ -297,8 +304,8 @@ static void pwm_samsung_manual_update(struct samsung_pwm_chip *chip,
 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }
 
-static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
-			      int duty_ns, int period_ns)
+static int __pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
+				int duty_ns, int period_ns, bool force_period)
 {
 	struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
 	struct samsung_pwm_channel *chan = pwm_get_chip_data(pwm);
@@ -319,7 +326,7 @@ static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	++tcnt;
 
 	/* Check to see if we are changing the clock rate of the PWM. */
-	if (chan->period_ns != period_ns) {
+	if (chan->period_ns != period_ns || force_period) {
 		unsigned long tin_rate;
 		u32 period;
 
@@ -378,6 +385,12 @@ static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
+static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			      int duty_ns, int period_ns)
+{
+	return __pwm_samsung_config(chip, pwm, duty_ns, period_ns, false);
+}
+
 static void pwm_samsung_set_invert(struct samsung_pwm_chip *chip,
 				   unsigned int channel, bool invert)
 {
@@ -589,51 +602,41 @@ static int pwm_samsung_remove(struct platform_device *pdev)
 }
 
 #ifdef CONFIG_PM_SLEEP
-static int pwm_samsung_suspend(struct device *dev)
+static int pwm_samsung_resume(struct device *dev)
 {
-	struct samsung_pwm_chip *chip = dev_get_drvdata(dev);
+	struct samsung_pwm_chip *our_chip = dev_get_drvdata(dev);
+	struct pwm_chip *chip = &our_chip->chip;
 	unsigned int i;
 
-	/*
-	 * No one preserves these values during suspend so reset them.
-	 * Otherwise driver leaves PWM unconfigured if same values are
-	 * passed to pwm_config() next time.
-	 */
-	for (i = 0; i < SAMSUNG_PWM_NUM; ++i) {
-		struct pwm_device *pwm = &chip->chip.pwms[i];
+	for (i = 0; i < SAMSUNG_PWM_NUM; i++) {
+		struct pwm_device *pwm = &chip->pwms[i];
 		struct samsung_pwm_channel *chan = pwm_get_chip_data(pwm);
 
 		if (!chan)
 			continue;
 
-		chan->period_ns = 0;
-		chan->duty_ns = 0;
-	}
-
-	return 0;
-}
+		if (our_chip->variant.output_mask & BIT(i))
+			pwm_samsung_set_invert(our_chip, i,
+					our_chip->inverter_mask & BIT(i));
 
-static int pwm_samsung_resume(struct device *dev)
-{
-	struct samsung_pwm_chip *chip = dev_get_drvdata(dev);
-	unsigned int chan;
+		if (chan->period_ns) {
+			__pwm_samsung_config(chip, pwm, chan->duty_ns,
+					     chan->period_ns, true);
+			/* needed to make PWM disable work on Odroid-XU3 */
+			pwm_samsung_manual_update(our_chip, pwm);
+		}
 
-	/*
-	 * Inverter setting must be preserved across suspend/resume
-	 * as nobody really seems to configure it more than once.
-	 */
-	for (chan = 0; chan < SAMSUNG_PWM_NUM; ++chan) {
-		if (chip->variant.output_mask & BIT(chan))
-			pwm_samsung_set_invert(chip, chan,
-					chip->inverter_mask & BIT(chan));
+		if (our_chip->disabled_mask & BIT(i))
+			pwm_samsung_disable(chip, pwm);
+		else
+			pwm_samsung_enable(chip, pwm);
 	}
 
 	return 0;
 }
 #endif
 
-static SIMPLE_DEV_PM_OPS(pwm_samsung_pm_ops, pwm_samsung_suspend,
-			 pwm_samsung_resume);
+static SIMPLE_DEV_PM_OPS(pwm_samsung_pm_ops, NULL, pwm_samsung_resume);
 
 static struct platform_driver pwm_samsung_driver = {
 	.driver		= {
-- 
1.9.1