[PATCH v6] pwm: atmel: Enable clk when pwm already enabled in bootloader

From: Guiting Shen
Date: Sat Jul 15 2023 - 22:07:52 EST


The driver would never call clk_enable() if the PWM channel was already
enabled in bootloader which lead to dump the warning message "the PWM
clock already disabled" when turning off the PWM channel.

Add atmel_pwm_enable_clk_if_on() in probe function to enable clock if
the PWM channel was already enabled in bootloader.

Signed-off-by: Guiting Shen <aarongt.shen@xxxxxxxxx>
---
drivers/pwm/pwm-atmel.c | 47 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 45 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index cdbc23649032..fc89282db645 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -36,7 +36,7 @@
#define PWM_SR 0x0C
#define PWM_ISR 0x1C
/* Bit field in SR */
-#define PWM_SR_ALL_CH_ON 0x0F
+#define PWM_SR_ALL_CH_MASK 0x0F

/* The following register is PWM channel related registers */
#define PWM_CH_REG_OFFSET 0x200
@@ -464,6 +464,42 @@ 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, bool on)
+{
+ unsigned int i, cnt = 0;
+ int ret = 0;
+ u32 sr;
+
+ sr = atmel_pwm_readl(atmel_pwm, PWM_SR) & PWM_SR_ALL_CH_MASK;
+ if (!sr)
+ return 0;
+
+ cnt = bitmap_weight((unsigned long *)&sr, atmel_pwm->chip.npwm);
+
+ if (!on)
+ goto disable_clk;
+
+ for (i = 0; i < cnt; i++) {
+ ret = clk_enable(atmel_pwm->clk);
+ if (ret) {
+ dev_err(atmel_pwm->chip.dev,
+ "failed to enable clock for pwm %pe\n",
+ ERR_PTR(ret));
+
+ cnt = i;
+ goto disable_clk;
+ }
+ }
+
+ return 0;
+
+disable_clk:
+ while (cnt--)
+ clk_disable(atmel_pwm->clk);
+
+ return ret;
+}
+
static int atmel_pwm_probe(struct platform_device *pdev)
{
struct atmel_pwm_chip *atmel_pwm;
@@ -496,16 +532,23 @@ static int atmel_pwm_probe(struct platform_device *pdev)
atmel_pwm->chip.ops = &atmel_pwm_ops;
atmel_pwm->chip.npwm = 4;

+ ret = atmel_pwm_enable_clk_if_on(atmel_pwm, true);
+ if (ret < 0)
+ goto unprepare_clk;
+
ret = pwmchip_add(&atmel_pwm->chip);
if (ret < 0) {
dev_err(&pdev->dev, "failed to add PWM chip %d\n", ret);
- goto unprepare_clk;
+ goto disable_clk;
}

platform_set_drvdata(pdev, atmel_pwm);

return ret;

+disable_clk:
+ atmel_pwm_enable_clk_if_on(atmel_pwm, false);
+
unprepare_clk:
clk_unprepare(atmel_pwm->clk);
return ret;
--
2.25.1