[PATCH] pwm: atmel: enable clk when pwm already enabled in bootloader

[Guiting Shen]

The driver would never call clk_eanble() if the pwm channel already
enable in bootloader which lead to dump the warning message of "the pwm
clk already disabled" when poweroff the pwm channel.

Add atmel_pwm_enanle_clk_if_on() in probe function to enable clk if the
pwm channel already enabled in bootloader.

Signed-off-by: Guiting Shen <aarongt.shen at gmail.com>
---
 drivers/pwm/pwm-atmel.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index cdbc23649032..385f12eb604c 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -464,6 +464,29 @@ static const struct of_device_id atmel_pwm_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
 
+static int atmel_pwm_enable_clk_if_on(struct atmel_pwm_chip *atmel_pwm)
+{
+	u32 sr, i;
+	int err;
+
+	sr = atmel_pwm_readl(atmel_pwm, PWM_SR);
+	if (!sr)
+		return 0;
+
+	for (i = 0; i < atmel_pwm->chip.npwm; i++) {
+		if (!(sr & (1 << i)))
+			continue;
+
+		err = clk_enable(atmel_pwm->clk);
+		if (err) {
+			dev_err(atmel_pwm->chip.dev, "enable clock error\n");
+			return err;
+		}
+	}
+
+	return 0;
+}
+
 static int atmel_pwm_probe(struct platform_device *pdev)
 {
 	struct atmel_pwm_chip *atmel_pwm;
@@ -504,6 +527,10 @@ static int atmel_pwm_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, atmel_pwm);
 
+	ret = atmel_pwm_enable_clk_if_on(atmel_pwm);
+	if (ret < 0)
+		goto unprepare_clk;
+
 	return ret;
 
 unprepare_clk:
-- 
2.25.1