Re: [PATCH 04/14] pwm: rockchip: Add support for hardware readout

Boris Brezillon
2016-06-04T06:24:26Z

On Fri, 3 Jun 2016 13:20:06 -0700
Brian Norris <briannorris@chromium.org> wrote:

> On Fri, Jun 03, 2016 at 10:23:02AM +0200, Boris Brezillon wrote:
> > Implement the ->get_state() function to expose initial state.
> >
> > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > ---
> > drivers/pwm/pwm-rockchip.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 67 insertions(+)
> >
> > diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
> > index 68d72ce..dfacf7d 100644
> > --- a/drivers/pwm/pwm-rockchip.c
> > +++ b/drivers/pwm/pwm-rockchip.c
> > @@ -51,6 +51,8 @@ struct rockchip_pwm_data {
> >
> > void (*set_enable)(struct pwm_chip *chip,
> > struct pwm_device *pwm, bool enable);
> > + void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
> > + struct pwm_state *state);
> > };
> >
> > static inline struct rockchip_pwm_chip *to_rockchip_pwm_chip(struct pwm_chip *c)
> > @@ -75,6 +77,19 @@ static void rockchip_pwm_set_enable_v1(struct pwm_chip *chip,
> > writel_relaxed(val, pc->base + pc->data->regs.ctrl);
> > }
> >
> > +static void rockchip_pwm_get_state_v1(struct pwm_chip *chip,
> > + struct pwm_device *pwm,
> > + struct pwm_state *state)
> > +{
> > + struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
> > + u32 enable_conf = PWM_CTRL_OUTPUT_EN | PWM_CTRL_TIMER_EN;
> > + u32 val;
> > +
> > + val = readl(pc->base + pc->data->regs.ctrl);
>
> Nit: I just noticed you've been starting to use readl()/writel() in this
> series, where previously {readl,writel}_relaxed() were being used. Any
> reason?

Because I'm lazy and usually don't take the time to think whether it's
safe of not to use the _relaxed() versions :-). Not sure you'll have a
noticeable improvement by using _relaxed() for a PWM device by the
way, but I can change that ;-).

>
> Anyway, LGTM:
>
> Reviewed-by: Brian Norris <briannorris@chromium.org>
> Tested-by: Brian Norris <briannorris@chromium.org>
>
> > + if ((val & enable_conf) == enable_conf)
> > + state->enabled = true;
> > +}
> > +
> > static void rockchip_pwm_set_enable_v2(struct pwm_chip *chip,
> > struct pwm_device *pwm, bool enable)
> > {
> > @@ -98,6 +113,53 @@ static void rockchip_pwm_set_enable_v2(struct pwm_chip *chip,
> > writel_relaxed(val, pc->base + pc->data->regs.ctrl);
> > }
> >
> > +static void rockchip_pwm_get_state_v2(struct pwm_chip *chip,
> > + struct pwm_device *pwm,
> > + struct pwm_state *state)
> > +{
> > + struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
> > + u32 enable_conf = PWM_OUTPUT_LEFT | PWM_LP_DISABLE | PWM_ENABLE |
> > + PWM_CONTINUOUS;
> > + u32 val;
> > +
> > + val = readl(pc->base + pc->data->regs.ctrl);
> > + if ((val & enable_conf) != enable_conf)
> > + return;
> > +
> > + state->enabled = true;
> > +
> > + if (!(val & PWM_DUTY_POSITIVE))
> > + state->polarity = PWM_POLARITY_INVERSED;
> > +}
> > +
> > +static void rockchip_pwm_get_state(struct pwm_chip *chip,
> > + struct pwm_device *pwm,
> > + struct pwm_state *state)
> > +{
> > + struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
> > + unsigned long clk_rate;
> > + u64 tmp;
> > + int ret;
> > +
> > + ret = clk_enable(pc->clk);
> > + if (ret)
> > + return;
> > +
> > + clk_rate = clk_get_rate(pc->clk);
> > +
> > + tmp = readl(pc->base + pc->data->regs.period);
> > + tmp *= pc->data->prescaler * NSEC_PER_SEC;
> > + state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
> > +
> > + tmp = readl(pc->base + pc->data->regs.duty);
> > + tmp *= pc->data->prescaler * NSEC_PER_SEC;
> > + state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
> > +
> > + pc->data->get_state(chip, pwm, state);
> > +
> > + clk_disable(pc->clk);
> > +}
> > +
> > static int rockchip_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > int duty_ns, int period_ns)
> > {
> > @@ -170,6 +232,7 @@ static void rockchip_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> > }
> >
> > static const struct pwm_ops rockchip_pwm_ops_v1 = {
> > + .get_state = rockchip_pwm_get_state,
> > .config = rockchip_pwm_config,
> > .enable = rockchip_pwm_enable,
> > .disable = rockchip_pwm_disable,
> > @@ -177,6 +240,7 @@ static const struct pwm_ops rockchip_pwm_ops_v1 = {
> > };
> >
> > static const struct pwm_ops rockchip_pwm_ops_v2 = {
> > + .get_state = rockchip_pwm_get_state,
> > .config = rockchip_pwm_config,
> > .set_polarity = rockchip_pwm_set_polarity,
> > .enable = rockchip_pwm_enable,
> > @@ -194,6 +258,7 @@ static const struct rockchip_pwm_data pwm_data_v1 = {
> > .prescaler = 2,
> > .ops = &rockchip_pwm_ops_v1,
> > .set_enable = rockchip_pwm_set_enable_v1,
> > + .get_state = rockchip_pwm_get_state_v1,
> > };
> >
> > static const struct rockchip_pwm_data pwm_data_v2 = {
> > @@ -206,6 +271,7 @@ static const struct rockchip_pwm_data pwm_data_v2 = {
> > .prescaler = 1,
> > .ops = &rockchip_pwm_ops_v2,
> > .set_enable = rockchip_pwm_set_enable_v2,
> > + .get_state = rockchip_pwm_get_state_v2,
> > };
> >
> > static const struct rockchip_pwm_data pwm_data_vop = {
> > @@ -218,6 +284,7 @@ static const struct rockchip_pwm_data pwm_data_vop = {
> > .prescaler = 1,
> > .ops = &rockchip_pwm_ops_v2,
> > .set_enable = rockchip_pwm_set_enable_v2,
> > + .get_state = rockchip_pwm_get_state_v2,
> > };
> >
> > static const struct of_device_id rockchip_pwm_dt_ids[] = {
> > --
> > 2.7.4
> >

--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering