Commit a2f68c7e authored by Guiting Shen's avatar Guiting Shen Committed by Thierry Reding
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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: default avatarGuiting Shen <aarongt.shen@gmail.com>
Reviewed-by: default avatarClaudiu Beznea <claudiu.beznea@tuxon.dev>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 0a41b0c5

drivers/pwm/pwm-atmel.c

+45 −2
Original line number Diff line number Diff line
@@ -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;