pwm: Add Allwinner SoC support

This adds a generic PWM framework driver for the PWM controller
found on Allwinner SoCs.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/Kconfig

@@ -284,6 +284,16 @@ config PWM_STI
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-sti.
 
+config PWM_SUN4I
+	tristate "Allwinner PWM support"
+	depends on ARCH_SUNXI || COMPILE_TEST
+	depends on HAS_IOMEM && COMMON_CLK
+	help
+	  Generic PWM framework driver for Allwinner SoCs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-sun4i.
+
 config PWM_TEGRA
 	tristate "NVIDIA Tegra PWM support"
 	depends on ARCH_TEGRA

drivers/pwm/Makefile

@@ -26,6 +26,7 @@ obj-$(CONFIG_PWM_ROCKCHIP)	+= pwm-rockchip.o
 obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_SPEAR)		+= pwm-spear.o
 obj-$(CONFIG_PWM_STI)		+= pwm-sti.o
+obj-$(CONFIG_PWM_SUN4I)		+= pwm-sun4i.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o
 obj-$(CONFIG_PWM_TIECAP)	+= pwm-tiecap.o
 obj-$(CONFIG_PWM_TIEHRPWM)	+= pwm-tiehrpwm.o

drivers/pwm/pwm-sun4i.c

+/*
+ * Driver for Allwinner sun4i Pulse Width Modulation Controller
+ *
+ * Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@free-electrons.com>
+ *
+ * Licensed under GPLv2.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.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/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 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_rdy;
+};
+
+struct sun4i_pwm_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	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_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			    int duty_ns, int period_ns)
+{
+	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
+	u32 prd, dty, val, clk_gate;
+	u64 clk_rate, div = 0;
+	unsigned int prescaler = 0;
+	int err;
+
+	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;
+		/*
+		 * 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;
+		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++) {
+			if (!prescaler_table[prescaler])
+				continue;
+			div = clk_rate;
+			do_div(div, prescaler_table[prescaler]);
+			div = div * period_ns;
+			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");
+			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));
+
+	if (clk_gate) {
+		val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
+		val |= clk_gate;
+		sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
+	}
+
+	spin_unlock(&sun4i_pwm->ctrl_lock);
+	clk_disable_unprepare(sun4i_pwm->clk);
+
+	return 0;
+}
+
+static int sun4i_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+				  enum pwm_polarity polarity)
+{
+	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;
+	}
+
+	spin_lock(&sun4i_pwm->ctrl_lock);
+	val = 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);
+
+	sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
+
+	spin_unlock(&sun4i_pwm->ctrl_lock);
+	clk_disable_unprepare(sun4i_pwm->clk);
+
+	return 0;
+}
+
+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;
+
+	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);
+	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;
+}
+
+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;
+
+	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);
+}
+
+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,
+	.owner = THIS_MODULE,
+};
+
+static const struct sun4i_pwm_data sun4i_pwm_data_a10 = {
+	.has_prescaler_bypass = false,
+	.has_rdy = false,
+};
+
+static const struct sun4i_pwm_data sun4i_pwm_data_a20 = {
+	.has_prescaler_bypass = true,
+	.has_rdy = true,
+};
+
+static const struct of_device_id sun4i_pwm_dt_ids[] = {
+	{
+		.compatible = "allwinner,sun4i-a10-pwm",
+		.data = &sun4i_pwm_data_a10,
+	}, {
+		.compatible = "allwinner,sun7i-a20-pwm",
+		.data = &sun4i_pwm_data_a20,
+	}, {
+		/* 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;
+	u32 val;
+	int i, ret;
+	const struct of_device_id *match;
+
+	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
+
+	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+	if (!pwm)
+		return -ENOMEM;
+
+	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);
+
+	pwm->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(pwm->clk))
+		return PTR_ERR(pwm->clk);
+
+	pwm->chip.dev = &pdev->dev;
+	pwm->chip.ops = &sun4i_pwm_ops;
+	pwm->chip.base = -1;
+	pwm->chip.npwm = 2;
+	pwm->chip.can_sleep = true;
+	pwm->chip.of_xlate = of_pwm_xlate_with_flags;
+	pwm->chip.of_pwm_n_cells = 3;
+	pwm->data = match->data;
+
+	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);
+		return ret;
+	}
+
+	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->chip.pwms[i].polarity = 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)
+{
+	struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&pwm->chip);
+}
+
+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");