diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/pwm/pwm-sun4i.c | 517 |
1 files changed, 517 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c new file mode 100644 index 000000000..482d5b9ce --- /dev/null +++ b/drivers/pwm/pwm-sun4i.c @@ -0,0 +1,517 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for Allwinner sun4i Pulse Width Modulation Controller + * + * Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@free-electrons.com> + * + * 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 <linux/bitops.h> +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/jiffies.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/reset.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/time.h> + +#define PWM_CTRL_REG 0x0 + +#define PWM_CH_PRD_BASE 0x4 +#define PWM_CH_PRD_OFFSET 0x4 +#define PWM_CH_PRD(ch) (PWM_CH_PRD_BASE + PWM_CH_PRD_OFFSET * (ch)) + +#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) +#define PWM_MODE BIT(7) +#define PWM_PULSE BIT(8) +#define PWM_BYPASS BIT(9) + +#define PWM_RDY_BASE 28 +#define PWM_RDY_OFFSET 1 +#define PWM_RDY(ch) BIT(PWM_RDY_BASE + PWM_RDY_OFFSET * (ch)) + +#define PWM_PRD(prd) (((prd) - 1) << 16) +#define PWM_PRD_MASK GENMASK(15, 0) + +#define PWM_DTY_MASK GENMASK(15, 0) + +#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[] = { + 120, + 180, + 240, + 360, + 480, + 0, + 0, + 0, + 12000, + 24000, + 36000, + 48000, + 72000, + 0, + 0, + 0, /* Actually 1 but tested separately */ +}; + +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; + unsigned long next_period[2]; +}; + +static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct sun4i_pwm_chip, chip); +} + +static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip, + unsigned long offset) +{ + return readl(chip->base + offset); +} + +static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip, + u32 val, unsigned long offset) +{ + writel(val, chip->base + offset); +} + +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); + 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); + + /* + * 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; + 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)) == + 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 = (u64)prescaler * NSEC_PER_SEC * PWM_REG_DTY(val); + state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); + + tmp = (u64)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, + const struct pwm_state *state, + u32 *dty, u32 *prd, unsigned int *prsclr, + bool *bypass) +{ + u64 clk_rate, div = 0; + unsigned int 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; + /* + * 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 * state->period + NSEC_PER_SEC / 2; + do_div(div, NSEC_PER_SEC); + if (div - 1 > PWM_PRD_MASK) + prescaler = 0; + } + + if (prescaler == 0) { + /* Go up from the first divider */ + for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) { + unsigned int pval = prescaler_table[prescaler]; + + if (!pval) + continue; + + div = clk_rate; + 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) + return -EINVAL; + } + + *prd = div; + div *= state->duty_cycle; + do_div(div, state->period); + *dty = div; + *prsclr = prescaler; + + return 0; +} + +static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip); + struct pwm_state cstate; + u32 ctrl, duty = 0, period = 0, val; + int ret; + unsigned int delay_us, prescaler = 0; + unsigned long now; + bool bypass; + + 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; + } + } + + ret = sun4i_pwm_calculate(sun4i_pwm, state, &duty, &period, &prescaler, + &bypass); + if (ret) { + dev_err(chip->dev, "period exceeds the maximum value\n"); + if (!cstate.enabled) + clk_disable_unprepare(sun4i_pwm->clk); + return ret; + } + + spin_lock(&sun4i_pwm->ctrl_lock); + ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); + + 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); + return 0; + } + + 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); + } + + 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 + + nsecs_to_jiffies(cstate.period + 1000); + + 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); + + sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); + + spin_unlock(&sun4i_pwm->ctrl_lock); + + if (state->enabled) + return 0; + + /* We need a full period to elapse before disabling the channel. */ + now = jiffies; + if (time_before(now, sun4i_pwm->next_period[pwm->hwpwm])) { + delay_us = jiffies_to_usecs(sun4i_pwm->next_period[pwm->hwpwm] - + now); + if ((delay_us / 500) > MAX_UDELAY_MS) + msleep(delay_us / 1000 + 1); + else + usleep_range(delay_us, delay_us * 2); + } + + spin_lock(&sun4i_pwm->ctrl_lock); + ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); + ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); + ctrl &= ~BIT_CH(PWM_EN, 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 = { + .apply = sun4i_pwm_apply, + .get_state = sun4i_pwm_get_state, + .owner = THIS_MODULE, +}; + +static const struct sun4i_pwm_data sun4i_pwm_dual_nobypass = { + .has_prescaler_bypass = false, + .npwm = 2, +}; + +static const struct sun4i_pwm_data sun4i_pwm_dual_bypass = { + .has_prescaler_bypass = true, + .npwm = 2, +}; + +static const struct sun4i_pwm_data sun4i_pwm_single_bypass = { + .has_prescaler_bypass = true, + .npwm = 1, +}; + +static const struct sun4i_pwm_data sun50i_a64_pwm_data = { + .has_prescaler_bypass = true, + .has_direct_mod_clk_output = true, + .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", + .data = &sun4i_pwm_dual_nobypass, + }, { + .compatible = "allwinner,sun5i-a10s-pwm", + .data = &sun4i_pwm_dual_bypass, + }, { + .compatible = "allwinner,sun5i-a13-pwm", + .data = &sun4i_pwm_single_bypass, + }, { + .compatible = "allwinner,sun7i-a20-pwm", + .data = &sun4i_pwm_dual_bypass, + }, { + .compatible = "allwinner,sun8i-h3-pwm", + .data = &sun4i_pwm_single_bypass, + }, { + .compatible = "allwinner,sun50i-a64-pwm", + .data = &sun50i_a64_pwm_data, + }, { + .compatible = "allwinner,sun50i-h6-pwm", + .data = &sun50i_h6_pwm_data, + }, { + /* sentinel */ + }, +}; +MODULE_DEVICE_TABLE(of, sun4i_pwm_dt_ids); + +static int sun4i_pwm_probe(struct platform_device *pdev) +{ + struct sun4i_pwm_chip *pwm; + struct resource *res; + int ret; + + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); + if (!pwm) + return -ENOMEM; + + pwm->data = of_device_get_match_data(&pdev->dev); + if (!pwm->data) + return -ENODEV; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + pwm->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(pwm->base)) + return PTR_ERR(pwm->base); + + /* + * 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)) + return dev_err_probe(&pdev->dev, PTR_ERR(pwm->clk), + "get mod clock failed\n"); + + if (!pwm->clk) { + pwm->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(pwm->clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(pwm->clk), + "get unnamed clock failed\n"); + } + + pwm->bus_clk = devm_clk_get_optional(&pdev->dev, "bus"); + if (IS_ERR(pwm->bus_clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(pwm->bus_clk), + "get bus clock failed\n"); + + pwm->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL); + if (IS_ERR(pwm->rst)) + return dev_err_probe(&pdev->dev, PTR_ERR(pwm->rst), + "get reset failed\n"); + + /* 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; + pwm->chip.base = -1; + pwm->chip.npwm = pwm->data->npwm; + pwm->chip.of_xlate = of_pwm_xlate_with_flags; + pwm->chip.of_pwm_n_cells = 3; + + spin_lock_init(&pwm->ctrl_lock); + + ret = pwmchip_add(&pwm->chip); + if (ret < 0) { + dev_err(&pdev->dev, "failed to add PWM chip: %d\n", 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; + + clk_disable_unprepare(pwm->bus_clk); + reset_control_assert(pwm->rst); + + return 0; +} + +static struct platform_driver sun4i_pwm_driver = { + .driver = { + .name = "sun4i-pwm", + .of_match_table = sun4i_pwm_dt_ids, + }, + .probe = sun4i_pwm_probe, + .remove = sun4i_pwm_remove, +}; +module_platform_driver(sun4i_pwm_driver); + +MODULE_ALIAS("platform:sun4i-pwm"); +MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>"); +MODULE_DESCRIPTION("Allwinner sun4i PWM driver"); +MODULE_LICENSE("GPL v2"); |