pwm: atmel: Enable clk when pwm already enabled in bootloader

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@gmail.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index 4b243c0e8490962f5685ea7386ec851237692ef8..03c7810416b845318e9e17fc831eada2bf7b87fc 100644 (file)
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -35,7 +35,7 @@
 #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
@@ -463,6 +463,42 @@ 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;
+       unsigned long sr;
+       int ret = 0;
+
+       sr = atmel_pwm_readl(atmel_pwm, PWM_SR) & PWM_SR_ALL_CH_MASK;
+       if (!sr)
+               return 0;
+
+       cnt = bitmap_weight(&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;
@@ -495,16 +531,23 @@ 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;