From patchwork Thu Apr 27 22:00:02 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandre Belloni X-Patchwork-Id: 756158 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3wDW8T5Srlz9sDC for ; Fri, 28 Apr 2017 08:00:09 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034178AbdD0WAI (ORCPT ); Thu, 27 Apr 2017 18:00:08 -0400 Received: from mail.free-electrons.com ([62.4.15.54]:49380 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1034173AbdD0WAH (ORCPT ); Thu, 27 Apr 2017 18:00:07 -0400 Received: by mail.free-electrons.com (Postfix, from userid 110) id D350E20C7C; Fri, 28 Apr 2017 00:00:05 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on mail.free-electrons.com X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,SHORTCIRCUIT shortcircuit=ham autolearn=disabled version=3.4.0 Received: from localhost (unknown [88.191.26.124]) by mail.free-electrons.com (Postfix) with ESMTPSA id 9E51F2076E; Fri, 28 Apr 2017 00:00:05 +0200 (CEST) From: Alexandre Belloni To: Thierry Reding , Olliver Schinagl Cc: Maxime Ripard , Chen-Yu Tsai , Boris Brezillon , linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Alexandre Belloni Subject: [PATCH] pwm: sun4i: switch to atomic PWM Date: Fri, 28 Apr 2017 00:00:02 +0200 Message-Id: <20170427220002.20266-1-alexandre.belloni@free-electrons.com> X-Mailer: git-send-email 2.11.0 Sender: linux-pwm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org Switch the driver to atomic PWM. This makes it easier to wait a proper amount of time when changing the duty cycle before disabling the channel (main use case is switching the duty cycle to 0 before disabling). Also, the hardware read out is now greatly improved as it was formerly only handling PWM polarity. Signed-off-by: Alexandre Belloni --- drivers/pwm/pwm-sun4i.c | 272 ++++++++++++++++++++++++++---------------------- 1 file changed, 150 insertions(+), 122 deletions(-) diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c index b0803f6c64d9..de300779c811 100644 --- a/drivers/pwm/pwm-sun4i.c +++ b/drivers/pwm/pwm-sun4i.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -27,7 +28,6 @@ #define PWMCH_OFFSET 15 #define PWM_PRESCAL_MASK GENMASK(3, 0) -#define PWM_PRESCAL_OFF 0 #define PWM_EN BIT(4) #define PWM_ACT_STATE BIT(5) #define PWM_CLK_GATING BIT(6) @@ -44,6 +44,11 @@ #define PWM_DTY_MASK GENMASK(15, 0) +#define PWM_MAX_PRD_US 198000000 +#define PWM_REG_PRD(reg) (((reg >> 16) & PWM_PRD_MASK) + 1) +#define PWM_REG_DTY(reg) (reg & PWM_DTY_MASK) +#define PWM_REG_PRESCAL(reg, chan) ((reg >> ((chan) * PWMCH_OFFSET)) & PWM_PRESCAL_MASK) + #define BIT_CH(bit, chan) ((bit) << ((chan) * PWMCH_OFFSET)) static const u32 prescaler_table[] = { @@ -96,26 +101,65 @@ static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip, writel(val, chip->base + offset); } -static int sun4i_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, - int duty_ns, int period_ns) +static void sun4i_pwm_get_state(struct pwm_chip *chip, + struct pwm_device *pwm, + struct pwm_state *state) { struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip); - u32 prd, dty, val, clk_gate; + u64 clk_rate, tmp; + u32 val; + unsigned int prescaler; + + clk_rate = clk_get_rate(sun4i_pwm->clk); + + val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); + + if ((val == PWM_PRESCAL_MASK) && sun4i_pwm->data->has_prescaler_bypass) + prescaler = 1; + else + prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)]; + + if (prescaler == 0) + return; + + if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm)) + state->polarity = PWM_POLARITY_NORMAL; + else + state->polarity = PWM_POLARITY_INVERSED; + + if (val & BIT_CH(PWM_CLK_GATING | PWM_EN, pwm->hwpwm)) + state->enabled = true; + else + state->enabled = false; + + val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm)); + + tmp = prescaler * NSEC_PER_SEC * PWM_REG_DTY(val); + state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); + + tmp = prescaler * NSEC_PER_SEC * PWM_REG_PRD(val); + state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); +} + +static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm, + struct pwm_state *state, + u32 *dty, u32 *prd, unsigned int *prsclr) +{ u64 clk_rate, div = 0; - unsigned int prescaler = 0; - int err; + unsigned int pval, prescaler = 0; clk_rate = clk_get_rate(sun4i_pwm->clk); if (sun4i_pwm->data->has_prescaler_bypass) { /* First, test without any prescaler when available */ prescaler = PWM_PRESCAL_MASK; + pval = 1; /* * When not using any prescaler, the clock period in nanoseconds * is not an integer so round it half up instead of * truncating to get less surprising values. */ - div = clk_rate * period_ns + NSEC_PER_SEC / 2; + div = clk_rate * state->period + NSEC_PER_SEC / 2; do_div(div, NSEC_PER_SEC); if (div - 1 > PWM_PRD_MASK) prescaler = 0; @@ -126,137 +170,139 @@ static int sun4i_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) { if (!prescaler_table[prescaler]) continue; + pval = prescaler_table[prescaler]; div = clk_rate; - do_div(div, prescaler_table[prescaler]); - div = div * period_ns; + do_div(div, pval); + div = div * state->period; do_div(div, NSEC_PER_SEC); if (div - 1 <= PWM_PRD_MASK) break; } - if (div - 1 > PWM_PRD_MASK) { - dev_err(chip->dev, "period exceeds the maximum value\n"); + if (div - 1 > PWM_PRD_MASK) return -EINVAL; - } - } - - prd = div; - div *= duty_ns; - do_div(div, period_ns); - dty = div; - - err = clk_prepare_enable(sun4i_pwm->clk); - if (err) { - dev_err(chip->dev, "failed to enable PWM clock\n"); - return err; - } - - spin_lock(&sun4i_pwm->ctrl_lock); - val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); - - if (sun4i_pwm->data->has_rdy && (val & PWM_RDY(pwm->hwpwm))) { - spin_unlock(&sun4i_pwm->ctrl_lock); - clk_disable_unprepare(sun4i_pwm->clk); - return -EBUSY; - } - - clk_gate = val & BIT_CH(PWM_CLK_GATING, pwm->hwpwm); - if (clk_gate) { - val &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); - sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG); } - val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); - val &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm); - val |= BIT_CH(prescaler, pwm->hwpwm); - sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG); - - val = (dty & PWM_DTY_MASK) | PWM_PRD(prd); - sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm)); + *prd = div; + div *= state->duty_cycle; + do_div(div, state->period); + *dty = div; + *prsclr = prescaler; - if (clk_gate) { - val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); - val |= clk_gate; - sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG); - } + div = (u64)pval * NSEC_PER_SEC * *prd; + state->period = DIV_ROUND_CLOSEST_ULL(div, clk_rate); - spin_unlock(&sun4i_pwm->ctrl_lock); - clk_disable_unprepare(sun4i_pwm->clk); + div = (u64)pval * NSEC_PER_SEC * *dty; + state->duty_cycle = DIV_ROUND_CLOSEST_ULL(div, clk_rate); return 0; } -static int sun4i_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, - enum pwm_polarity polarity) +static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) { struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip); - u32 val; - int ret; - - ret = clk_prepare_enable(sun4i_pwm->clk); - if (ret) { - dev_err(chip->dev, "failed to enable PWM clock\n"); - return ret; + struct pwm_state cstate; + u32 ctrl; + int delay_us, ret; + bool needs_delay = false, prescaler_changed = false; + + pwm_get_state(pwm, &cstate); + + if (!cstate.enabled) { + ret = clk_prepare_enable(sun4i_pwm->clk); + if (ret) { + dev_err(chip->dev, "failed to enable PWM clock\n"); + return ret; + } } spin_lock(&sun4i_pwm->ctrl_lock); - val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); + ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); - if (polarity != PWM_POLARITY_NORMAL) - val &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm); - else - val |= BIT_CH(PWM_ACT_STATE, pwm->hwpwm); + if ((cstate.period != state->period) || + (cstate.duty_cycle != state->duty_cycle)) { + u32 period, duty, val; + unsigned int prescaler; - sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG); + needs_delay = true; - spin_unlock(&sun4i_pwm->ctrl_lock); - clk_disable_unprepare(sun4i_pwm->clk); + ret = sun4i_pwm_calculate(sun4i_pwm, state, + &duty, &period, &prescaler); + if (ret) { + dev_err(chip->dev, "period exceeds the maximum value\n"); + spin_unlock(&sun4i_pwm->ctrl_lock); + if (!cstate.enabled) + clk_disable_unprepare(sun4i_pwm->clk); + return ret; + } - return 0; -} + if (PWM_REG_PRESCAL(ctrl, pwm->hwpwm) != prescaler) { + prescaler_changed = true; + /* Prescaler changed, the clock has to be gated */ + ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); + sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); -static int sun4i_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) -{ - struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip); - u32 val; - int ret; + ctrl &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm); + ctrl |= BIT_CH(prescaler, pwm->hwpwm); + } - ret = clk_prepare_enable(sun4i_pwm->clk); - if (ret) { - dev_err(chip->dev, "failed to enable PWM clock\n"); - return ret; + val = (duty & PWM_DTY_MASK) | PWM_PRD(period); + sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm)); } - spin_lock(&sun4i_pwm->ctrl_lock); - val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); - val |= BIT_CH(PWM_EN, pwm->hwpwm); - val |= BIT_CH(PWM_CLK_GATING, pwm->hwpwm); - sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG); - spin_unlock(&sun4i_pwm->ctrl_lock); - - return 0; -} + if (state->polarity != PWM_POLARITY_NORMAL) + ctrl &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm); + else + ctrl |= BIT_CH(PWM_ACT_STATE, pwm->hwpwm); + + ctrl |= BIT_CH(PWM_CLK_GATING, pwm->hwpwm); + if (state->enabled) { + ctrl |= BIT_CH(PWM_EN, pwm->hwpwm); + } else if (!needs_delay) { + ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm); + ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); + } -static void sun4i_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) -{ - struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip); - u32 val; + sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); - spin_lock(&sun4i_pwm->ctrl_lock); - val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); - val &= ~BIT_CH(PWM_EN, pwm->hwpwm); - val &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); - sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG); spin_unlock(&sun4i_pwm->ctrl_lock); - clk_disable_unprepare(sun4i_pwm->clk); + if (!needs_delay) + return 0; + + /* We need a full (previous) period to elapse before disabling the + * channel. If a ready bit is available, wait for it instead of waiting + * for a full period. + * + * If the new period is greater than the previous one, the prescaler may + * have changed and the previous period may go slower. + * + */ + delay_us = max(state->period / 1000 + 1, cstate.period / 1000 + 1); + if ((cstate.enabled && !state->enabled) || !sun4i_pwm->data->has_rdy) + usleep_range(delay_us, delay_us * 2); + else + readl_poll_timeout(sun4i_pwm->base + PWM_CTRL_REG, ctrl, + !(ctrl & PWM_RDY(pwm->hwpwm)), + delay_us / 4, PWM_MAX_PRD_US); + + if (!state->enabled) { + spin_lock(&sun4i_pwm->ctrl_lock); + ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); + ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); + sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); + spin_unlock(&sun4i_pwm->ctrl_lock); + + clk_disable_unprepare(sun4i_pwm->clk); + } + + return 0; } static const struct pwm_ops sun4i_pwm_ops = { - .config = sun4i_pwm_config, - .set_polarity = sun4i_pwm_set_polarity, - .enable = sun4i_pwm_enable, - .disable = sun4i_pwm_disable, + .apply = sun4i_pwm_apply, + .get_state = sun4i_pwm_get_state, .owner = THIS_MODULE, }; @@ -316,8 +362,7 @@ static int sun4i_pwm_probe(struct platform_device *pdev) { struct sun4i_pwm_chip *pwm; struct resource *res; - u32 val; - int i, ret; + int ret; const struct of_device_id *match; match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev); @@ -354,24 +399,7 @@ static int sun4i_pwm_probe(struct platform_device *pdev) platform_set_drvdata(pdev, pwm); - ret = clk_prepare_enable(pwm->clk); - if (ret) { - dev_err(&pdev->dev, "failed to enable PWM clock\n"); - goto clk_error; - } - - val = sun4i_pwm_readl(pwm, PWM_CTRL_REG); - for (i = 0; i < pwm->chip.npwm; i++) - if (!(val & BIT_CH(PWM_ACT_STATE, i))) - pwm_set_polarity(&pwm->chip.pwms[i], - PWM_POLARITY_INVERSED); - clk_disable_unprepare(pwm->clk); - return 0; - -clk_error: - pwmchip_remove(&pwm->chip); - return ret; } static int sun4i_pwm_remove(struct platform_device *pdev)