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SubjectRe: [PATCH v6] pwm: atmel: Enable clk when pwm already enabled in bootloader
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On 16.07.2023 05:06, Guiting Shen wrote:
> 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>

> ---
> 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;

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