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Message-ID: <20170703203957.03f3d1db@bbrezillon>
Date: Mon, 3 Jul 2017 20:39:57 +0200
From: Boris Brezillon <boris.brezillon@...e-electrons.com>
To: David Wu <david.wu@...k-chips.com>
Cc: thierry.reding@...il.com, heiko@...ech.de, robh+dt@...nel.org,
catalin.marinas@....com, briannorris@...omium.org,
dianders@...omium.org, mark.rutland@....com,
huangtao@...k-chips.com, linux-pwm@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] pwm: rockchip: Add atomic updated feature for
rk3328
On Thu, 29 Jun 2017 20:27:50 +0800
David Wu <david.wu@...k-chips.com> wrote:
> The rk3328 soc supports atomic update, we could lock the configuration
> of period and duty at first, after unlock is configured, the period and
> duty are effective at the same time.
>
> If the polarity, period and duty need to be configured together,
> the way for atomic update is "configure lock and old polarity" ->
> "configure period and duty" -> "configure unlock and new polarity".
>
> Signed-off-by: David Wu <david.wu@...k-chips.com>
> ---
> .../devicetree/bindings/pwm/pwm-rockchip.txt | 1 +
> drivers/pwm/pwm-rockchip.c | 50 +++++++++++++++++++---
> 2 files changed, 46 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt b/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
> index 2350ef9..152c736 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
> +++ b/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
> @@ -4,6 +4,7 @@ Required properties:
> - compatible: should be "rockchip,<name>-pwm"
> "rockchip,rk2928-pwm": found on RK29XX,RK3066 and RK3188 SoCs
> "rockchip,rk3288-pwm": found on RK3288 SoC
> + "rockchip,rk3328-pwm": found on RK3328 SoC
> "rockchip,vop-pwm": found integrated in VOP on RK3288 SoC
> - reg: physical base address and length of the controller's registers
> - clocks: See ../clock/clock-bindings.txt
> diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
> index eb630ff..d8801ae8 100644
> --- a/drivers/pwm/pwm-rockchip.c
> +++ b/drivers/pwm/pwm-rockchip.c
> @@ -29,6 +29,7 @@
> #define PWM_INACTIVE_POSITIVE (1 << 4)
> #define PWM_POLARITY_MASK (PWM_DUTY_POSITIVE | PWM_INACTIVE_POSITIVE)
> #define PWM_OUTPUT_LEFT (0 << 5)
> +#define PWM_LOCK_EN (1 << 6)
> #define PWM_LP_DISABLE (0 << 8)
>
> struct rockchip_pwm_chip {
> @@ -50,6 +51,7 @@ struct rockchip_pwm_data {
> struct rockchip_pwm_regs regs;
> unsigned int prescaler;
> bool supports_polarity;
> + bool supports_atomic_update;
Yet another customization. Don't you think we can extract common parts,
expose them as helpers and then have 3 different pwm_ops (with 3
different ->apply() implementation), one for each IP revision.
> const struct pwm_ops *ops;
>
> void (*set_enable)(struct pwm_chip *chip,
> @@ -201,6 +203,14 @@ static void rockchip_pwm_config_v2(struct pwm_chip *chip,
> clk_rate = clk_get_rate(pc->clk);
>
> /*
> + * Lock the period and duty of previous configuration, then
> + * change the duty and period, that would not be effective.
> + */
> + ctrl = readl_relaxed(pc->base + pc->data->regs.ctrl);
> + ctrl |= PWM_LOCK_EN;
> + writel_relaxed(ctrl, pc->base + pc->data->regs.ctrl);
> +
> + /*
> * Since period and duty cycle registers have a width of 32
> * bits, every possible input period can be obtained using the
> * default prescaler value for all practical clock rate values.
> @@ -222,6 +232,12 @@ static void rockchip_pwm_config_v2(struct pwm_chip *chip,
> else
> ctrl |= PWM_DUTY_POSITIVE | PWM_INACTIVE_NEGATIVE;
>
> + /*
> + * Unlock and set polarity at the same time,
> + * the configuration of duty, period and polarity
> + * would be effective together at next period.
> + */
> + ctrl &= ~PWM_LOCK_EN;
> writel(ctrl, pc->base + pc->data->regs.ctrl);
> }
>
> @@ -261,11 +277,18 @@ static int rockchip_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> if (ret)
> return ret;
>
> - if (state->polarity != curstate.polarity && enabled) {
> - ret = rockchip_pwm_enable(chip, pwm, false);
> - if (ret)
> - goto out;
> - enabled = false;
> + /*
> + * If the atomic update is supported, then go to the pwm config,
> + * no need to do this, it could ensure the atomic update for polarity
> + * changed.
> + */
> + if (pc->data->supports_atomic_update) {
> + if (state->polarity != curstate.polarity && enabled) {
> + ret = rockchip_pwm_enable(chip, pwm, false);
> + if (ret)
> + goto out;
> + enabled = false;
> + }
> }
>
> pc->data->pwm_config(chip, pwm, state->duty_cycle,
> @@ -345,9 +368,26 @@ static int rockchip_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> .pwm_config = rockchip_pwm_config_v2,
> };
>
> +static const struct rockchip_pwm_data pwm_data_v3 = {
> + .regs = {
> + .duty = 0x08,
> + .period = 0x04,
> + .cntr = 0x00,
> + .ctrl = 0x0c,
> + },
> + .prescaler = 1,
> + .supports_polarity = true,
> + .supports_atomic_update = true,
> + .ops = &rockchip_pwm_ops_v2,
> + .set_enable = rockchip_pwm_set_enable_v2,
> + .get_state = rockchip_pwm_get_state_v2,
> + .pwm_config = rockchip_pwm_config_v2,
> +};
> +
> static const struct of_device_id rockchip_pwm_dt_ids[] = {
> { .compatible = "rockchip,rk2928-pwm", .data = &pwm_data_v1},
> { .compatible = "rockchip,rk3288-pwm", .data = &pwm_data_v2},
> + { .compatible = "rockchip,rk3328-pwm", .data = &pwm_data_v3},
> { .compatible = "rockchip,vop-pwm", .data = &pwm_data_vop},
> { /* sentinel */ }
> };
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