1 files changed, 503 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
new file mode 100644
index 000000000..37d75e252
--- /dev/null
+++ b/drivers/pwm/pwm-sun4i.c
@@ -0,0 +1,503 @@
+// 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;
+};
+
+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 int 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 0;
+	}
+
+	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 0;
+
+	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);
+
+	return 0;
+}
+
+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;
+	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));
+
+	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. */
+	delay_us = DIV_ROUND_UP_ULL(cstate.period, NSEC_PER_USEC);
+	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 *sun4ichip;
+	int ret;
+
+	sun4ichip = devm_kzalloc(&pdev->dev, sizeof(*sun4ichip), GFP_KERNEL);
+	if (!sun4ichip)
+		return -ENOMEM;
+
+	sun4ichip->data = of_device_get_match_data(&pdev->dev);
+	if (!sun4ichip->data)
+		return -ENODEV;
+
+	sun4ichip->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(sun4ichip->base))
+		return PTR_ERR(sun4ichip->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.
+	 */
+	sun4ichip->clk = devm_clk_get_optional(&pdev->dev, "mod");
+	if (IS_ERR(sun4ichip->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(sun4ichip->clk),
+				     "get mod clock failed\n");
+
+	if (!sun4ichip->clk) {
+		sun4ichip->clk = devm_clk_get(&pdev->dev, NULL);
+		if (IS_ERR(sun4ichip->clk))
+			return dev_err_probe(&pdev->dev, PTR_ERR(sun4ichip->clk),
+					     "get unnamed clock failed\n");
+	}
+
+	sun4ichip->bus_clk = devm_clk_get_optional(&pdev->dev, "bus");
+	if (IS_ERR(sun4ichip->bus_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(sun4ichip->bus_clk),
+				     "get bus clock failed\n");
+
+	sun4ichip->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
+	if (IS_ERR(sun4ichip->rst))
+		return dev_err_probe(&pdev->dev, PTR_ERR(sun4ichip->rst),
+				     "get reset failed\n");
+
+	/* Deassert reset */
+	ret = reset_control_deassert(sun4ichip->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(sun4ichip->bus_clk);
+	if (ret) {
+		dev_err(&pdev->dev, "cannot prepare and enable bus_clk %pe\n",
+			ERR_PTR(ret));
+		goto err_bus;
+	}
+
+	sun4ichip->chip.dev = &pdev->dev;
+	sun4ichip->chip.ops = &sun4i_pwm_ops;
+	sun4ichip->chip.npwm = sun4ichip->data->npwm;
+
+	spin_lock_init(&sun4ichip->ctrl_lock);
+
+	ret = pwmchip_add(&sun4ichip->chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
+		goto err_pwm_add;
+	}
+
+	platform_set_drvdata(pdev, sun4ichip);
+
+	return 0;
+
+err_pwm_add:
+	clk_disable_unprepare(sun4ichip->bus_clk);
+err_bus:
+	reset_control_assert(sun4ichip->rst);
+
+	return ret;
+}
+
+static int sun4i_pwm_remove(struct platform_device *pdev)
+{
+	struct sun4i_pwm_chip *sun4ichip = platform_get_drvdata(pdev);
+
+	pwmchip_remove(&sun4ichip->chip);
+
+	clk_disable_unprepare(sun4ichip->bus_clk);
+	reset_control_assert(sun4ichip->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");