--- a/drivers/pwm/pwm-sun4i.c +++ b/drivers/pwm/pwm-sun4i.c @@ -3,6 +3,10 @@ * Driver for Allwinner sun4i Pulse Width Modulation Controller * * Copyright (C) 2014 Alexandre Belloni + * + * Limitations: + * - When outputing the source clock directly, the PWM logic will be bypassed + * and the currently running period is not guaranteed to be completed */ #include @@ -16,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -72,12 +77,15 @@ static const u32 prescaler_table[] = { struct sun4i_pwm_data { bool has_prescaler_bypass; + bool has_direct_mod_clk_output; unsigned int npwm; }; struct sun4i_pwm_chip { struct pwm_chip chip; + struct clk *bus_clk; struct clk *clk; + struct reset_control *rst; void __iomem *base; spinlock_t ctrl_lock; const struct sun4i_pwm_data *data; @@ -115,6 +123,20 @@ static void sun4i_pwm_get_state(struct p val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); + /* + * PWM chapter in H6 manual has a diagram which explains that if bypass + * bit is set, no other setting has any meaning. Even more, experiment + * proved that also enable bit is ignored in this case. + */ + if ((val & BIT_CH(PWM_BYPASS, pwm->hwpwm)) && + sun4i_pwm->data->has_direct_mod_clk_output) { + state->period = DIV_ROUND_UP_ULL(NSEC_PER_SEC, clk_rate); + state->duty_cycle = DIV_ROUND_UP_ULL(state->period, 2); + state->polarity = PWM_POLARITY_NORMAL; + state->enabled = true; + return; + } + if ((PWM_REG_PRESCAL(val, pwm->hwpwm) == PWM_PRESCAL_MASK) && sun4i_pwm->data->has_prescaler_bypass) prescaler = 1; @@ -146,13 +168,24 @@ static void sun4i_pwm_get_state(struct p static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm, const struct pwm_state *state, - u32 *dty, u32 *prd, unsigned int *prsclr) + u32 *dty, u32 *prd, unsigned int *prsclr, + bool *bypass) { u64 clk_rate, div = 0; unsigned int pval, prescaler = 0; clk_rate = clk_get_rate(sun4i_pwm->clk); + *bypass = sun4i_pwm->data->has_direct_mod_clk_output && + state->enabled && + (state->period * clk_rate >= NSEC_PER_SEC) && + (state->period * clk_rate < 2 * NSEC_PER_SEC) && + (state->duty_cycle * clk_rate * 2 >= NSEC_PER_SEC); + + /* Skip calculation of other parameters if we bypass them */ + if (*bypass) + return 0; + if (sun4i_pwm->data->has_prescaler_bypass) { /* First, test without any prescaler when available */ prescaler = PWM_PRESCAL_MASK; @@ -200,10 +233,11 @@ static int sun4i_pwm_apply(struct pwm_ch { struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip); struct pwm_state cstate; - u32 ctrl; + u32 ctrl, duty, period, val; int ret; - unsigned int delay_us; + unsigned int delay_us, prescaler; unsigned long now; + bool bypass; pwm_get_state(pwm, &cstate); @@ -218,43 +252,50 @@ static int sun4i_pwm_apply(struct pwm_ch spin_lock(&sun4i_pwm->ctrl_lock); ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); - if ((cstate.period != state->period) || - (cstate.duty_cycle != state->duty_cycle)) { - u32 period, duty, val; - unsigned int prescaler; + ret = sun4i_pwm_calculate(sun4i_pwm, state, &duty, &period, &prescaler, + &bypass); + 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; + } - ret = sun4i_pwm_calculate(sun4i_pwm, state, - &duty, &period, &prescaler); - if (ret) { - dev_err(chip->dev, "period exceeds the maximum value\n"); + if (sun4i_pwm->data->has_direct_mod_clk_output) { + if (bypass) { + ctrl |= BIT_CH(PWM_BYPASS, pwm->hwpwm); + /* We can skip other parameter */ + sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); spin_unlock(&sun4i_pwm->ctrl_lock); - if (!cstate.enabled) - clk_disable_unprepare(sun4i_pwm->clk); - return ret; + return 0; + } else { + ctrl &= ~BIT_CH(PWM_BYPASS, pwm->hwpwm); } + } - if (PWM_REG_PRESCAL(ctrl, pwm->hwpwm) != prescaler) { - /* 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); - - ctrl &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm); - ctrl |= BIT_CH(prescaler, pwm->hwpwm); - } + if (PWM_REG_PRESCAL(ctrl, pwm->hwpwm) != prescaler) { + /* 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); - val = (duty & PWM_DTY_MASK) | PWM_PRD(period); - sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm)); - sun4i_pwm->next_period[pwm->hwpwm] = jiffies + - usecs_to_jiffies(cstate.period / 1000 + 1); - sun4i_pwm->needs_delay[pwm->hwpwm] = true; + ctrl &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm); + ctrl |= BIT_CH(prescaler, pwm->hwpwm); } + val = (duty & PWM_DTY_MASK) | PWM_PRD(period); + sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm)); + sun4i_pwm->next_period[pwm->hwpwm] = jiffies + + usecs_to_jiffies(cstate.period / 1000 + 1); + sun4i_pwm->needs_delay[pwm->hwpwm] = true; + 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 (!sun4i_pwm->needs_delay[pwm->hwpwm]) { @@ -320,6 +361,12 @@ static const struct sun4i_pwm_data sun4i .npwm = 1, }; +static const struct sun4i_pwm_data sun50i_h6_pwm_data = { + .has_prescaler_bypass = true, + .has_direct_mod_clk_output = true, + .npwm = 2, +}; + static const struct of_device_id sun4i_pwm_dt_ids[] = { { .compatible = "allwinner,sun4i-a10-pwm", @@ -337,6 +384,9 @@ static const struct of_device_id sun4i_p .compatible = "allwinner,sun8i-h3-pwm", .data = &sun4i_pwm_single_bypass, }, { + .compatible = "allwinner,sun50i-h6-pwm", + .data = &sun50i_h6_pwm_data, + }, { /* sentinel */ }, }; @@ -361,9 +411,69 @@ static int sun4i_pwm_probe(struct platfo if (IS_ERR(pwm->base)) return PTR_ERR(pwm->base); - pwm->clk = devm_clk_get(&pdev->dev, NULL); - if (IS_ERR(pwm->clk)) + /* + * All hardware variants need a source clock that is divided and + * then feeds the counter that defines the output wave form. In the + * device tree this clock is either unnamed or called "mod". + * Some variants (e.g. H6) need another clock to access the + * hardware registers; this is called "bus". + * So we request "mod" first (and ignore the corner case that a + * parent provides a "mod" clock while the right one would be the + * unnamed one of the PWM device) and if this is not found we fall + * back to the first clock of the PWM. + */ + pwm->clk = devm_clk_get_optional(&pdev->dev, "mod"); + if (IS_ERR(pwm->clk)) { + if (PTR_ERR(pwm->rst) != -EPROBE_DEFER) + dev_err(&pdev->dev, "get mod clock failed %pe\n", + pwm->clk); return PTR_ERR(pwm->clk); + } + + if (!pwm->clk) { + pwm->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(pwm->clk)) { + if (PTR_ERR(pwm->rst) != -EPROBE_DEFER) + dev_err(&pdev->dev, "get unnamed clock failed %pe\n", + pwm->clk); + return PTR_ERR(pwm->clk); + } + } + + pwm->bus_clk = devm_clk_get_optional(&pdev->dev, "bus"); + if (IS_ERR(pwm->bus_clk)) { + if (PTR_ERR(pwm->rst) != -EPROBE_DEFER) + dev_err(&pdev->dev, "get bus clock failed %pe\n", + pwm->bus_clk); + return PTR_ERR(pwm->bus_clk); + } + + pwm->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL); + if (IS_ERR(pwm->rst)) { + if (PTR_ERR(pwm->rst) != -EPROBE_DEFER) + dev_err(&pdev->dev, "get reset failed %pe\n", + pwm->rst); + return PTR_ERR(pwm->rst); + } + + /* Deassert reset */ + ret = reset_control_deassert(pwm->rst); + if (ret) { + dev_err(&pdev->dev, "cannot deassert reset control: %pe\n", + ERR_PTR(ret)); + return ret; + } + + /* + * We're keeping the bus clock on for the sake of simplicity. + * Actually it only needs to be on for hardware register accesses. + */ + ret = clk_prepare_enable(pwm->bus_clk); + if (ret) { + dev_err(&pdev->dev, "cannot prepare and enable bus_clk %pe\n", + ERR_PTR(ret)); + goto err_bus; + } pwm->chip.dev = &pdev->dev; pwm->chip.ops = &sun4i_pwm_ops; @@ -377,19 +487,34 @@ static int sun4i_pwm_probe(struct platfo ret = pwmchip_add(&pwm->chip); if (ret < 0) { dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); - return ret; + goto err_pwm_add; } platform_set_drvdata(pdev, pwm); return 0; + +err_pwm_add: + clk_disable_unprepare(pwm->bus_clk); +err_bus: + reset_control_assert(pwm->rst); + + return ret; } static int sun4i_pwm_remove(struct platform_device *pdev) { struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev); + int ret; + + ret = pwmchip_remove(&pwm->chip); + if (ret) + return ret; - return pwmchip_remove(&pwm->chip); + clk_disable_unprepare(pwm->bus_clk); + reset_control_assert(pwm->rst); + + return 0; } static struct platform_driver sun4i_pwm_driver = {