Hello,
On Fri, Oct 04, 2019 at 03:32:02PM +0200, Rasmus Villemoes wrote:
> In preparation for supporting setting the polarity, switch the driver
> to support the ->apply method.
>
> Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/pwm/pwm-mxs.c | 70 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 70 insertions(+)
>
> diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
> index b14376b47ac8..10efd3de0bb3 100644
> --- a/drivers/pwm/pwm-mxs.c
> +++ b/drivers/pwm/pwm-mxs.c
> @@ -26,6 +26,7 @@
> #define PERIOD_PERIOD_MAX 0x10000
> #define PERIOD_ACTIVE_HIGH (3 << 16)
> #define PERIOD_INACTIVE_LOW (2 << 18)
> +#define PERIOD_POLARITY_NORMAL (PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW)
> #define PERIOD_CDIV(div) (((div) & 0x7) << 20)
> #define PERIOD_CDIV_MAX 8
>
> @@ -41,6 +42,74 @@ struct mxs_pwm_chip {
>
> #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
>
> +static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> +{
> + struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
> + int ret, div = 0;
> + unsigned int period_cycles, duty_cycles;
> + unsigned long rate;
> + unsigned long long c;
> +
> + if (state->polarity != PWM_POLARITY_NORMAL)
> + return -ENOTSUPP;
> +
> + /*
> + * If the PWM channel is disabled, make sure to turn on the
> + * clock before calling clk_get_rate() and writing to the
> + * registers. Otherwise, just keep it enabled.
> + */
> + if (!pwm_is_enabled(pwm)) {
> + ret = clk_prepare_enable(mxs->clk);
> + if (ret)
> + return ret;
> + }
> +
> + if (!state->enabled && pwm_is_enabled(pwm))
> + writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
@Thierry: I wonder if it would be beneficial to stop the calculation of
register contents if !state->enabled here. The only drawback (I'm aware)
is that pwm_get_state won't return the previously set .period and
.duty_cycle. (I also wonder if we should return (e.g.) .duty = 0,
.period = 1 in pwm_get_state() if the PWM is off.)
For the patch (which is orthogonal regarding the above question):
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
