1 files changed, 418 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
new file mode 100644
index 000000000000..b95115cdaea7
--- /dev/null
+++ b/drivers/pwm/pwm-sti.c
@@ -0,0 +1,418 @@
+/*
+ * PWM device driver for ST SoCs.
+ * Author: Ajit Pal Singh <[email protected]>
+ *
+ * Copyright (C) 2013-2014 STMicroelectronics (R&D) Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/math64.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+
+#define STI_DS_REG(ch)	(4 * (ch))	/* Channel's Duty Cycle register */
+#define STI_PWMCR	0x50		/* Control/Config register */
+#define STI_INTEN	0x54		/* Interrupt Enable/Disable register */
+#define PWM_PRESCALE_LOW_MASK		0x0f
+#define PWM_PRESCALE_HIGH_MASK		0xf0
+
+/* Regfield IDs */
+enum {
+	PWMCLK_PRESCALE_LOW,
+	PWMCLK_PRESCALE_HIGH,
+	PWM_EN,
+	PWM_INT_EN,
+
+	/* Keep last */
+	MAX_REGFIELDS
+};
+
+struct sti_pwm_compat_data {
+	const struct reg_field *reg_fields;
+	unsigned int num_chan;
+	unsigned int max_pwm_cnt;
+	unsigned int max_prescale;
+};
+
+struct sti_pwm_chip {
+	struct device *dev;
+	struct clk *clk;
+	unsigned long clk_rate;
+	struct regmap *regmap;
+	struct sti_pwm_compat_data *cdata;
+	struct regmap_field *prescale_low;
+	struct regmap_field *prescale_high;
+	struct regmap_field *pwm_en;
+	struct regmap_field *pwm_int_en;
+	struct pwm_chip chip;
+	struct pwm_device *cur;
+	unsigned int en_count;
+	struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
+	void __iomem *mmio;
+};
+
+static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
+	[PWMCLK_PRESCALE_LOW]	= REG_FIELD(STI_PWMCR, 0, 3),
+	[PWMCLK_PRESCALE_HIGH]	= REG_FIELD(STI_PWMCR, 11, 14),
+	[PWM_EN]		= REG_FIELD(STI_PWMCR, 9, 9),
+	[PWM_INT_EN]		= REG_FIELD(STI_INTEN, 0, 0),
+};
+
+static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct sti_pwm_chip, chip);
+}
+
+/*
+ * Calculate the prescaler value corresponding to the period.
+ */
+static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
+				unsigned int *prescale)
+{
+	struct sti_pwm_compat_data *cdata = pc->cdata;
+	unsigned long val;
+	unsigned int ps;
+
+	/*
+	 * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
+	 */
+	val = NSEC_PER_SEC / pc->clk_rate;
+	val *= cdata->max_pwm_cnt + 1;
+
+	if (period % val) {
+		return -EINVAL;
+	} else {
+		ps  = period / val - 1;
+		if (ps > cdata->max_prescale)
+			return -EINVAL;
+	}
+	*prescale = ps;
+
+	return 0;
+}
+
+/* Calculate the number of PWM devices configured with a period. */
+static unsigned int sti_pwm_count_configured(struct pwm_chip *chip)
+{
+	struct pwm_device *pwm;
+	unsigned int ncfg = 0;
+	unsigned int i;
+
+	for (i = 0; i < chip->npwm; i++) {
+		pwm = &chip->pwms[i];
+		if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
+			if (pwm_get_period(pwm))
+				ncfg++;
+		}
+	}
+
+	return ncfg;
+}
+
+/*
+ * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
+ * The only way to change the period (apart from changing the PWM input clock)
+ * is to change the PWM clock prescaler.
+ * The prescaler is of 8 bits, so 256 prescaler values and hence
+ * 256 possible period values are supported (for a particular clock rate).
+ * The requested period will be applied only if it matches one of these
+ * 256 values.
+ */
+static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			 int duty_ns, int period_ns)
+{
+	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+	struct sti_pwm_compat_data *cdata = pc->cdata;
+	struct pwm_device *cur = pc->cur;
+	struct device *dev = pc->dev;
+	unsigned int prescale = 0, pwmvalx;
+	int ret;
+	unsigned int ncfg;
+	bool period_same = false;
+
+	ncfg = sti_pwm_count_configured(chip);
+	if (ncfg)
+		period_same = (period_ns == pwm_get_period(cur));
+
+	/* Allow configuration changes if one of the
+	 * following conditions satisfy.
+	 * 1. No channels have been configured.
+	 * 2. Only one channel has been configured and the new request
+	 *    is for the same channel.
+	 * 3. Only one channel has been configured and the new request is
+	 *    for a new channel and period of the new channel is same as
+	 *    the current configured period.
+	 * 4. More than one channels are configured and period of the new
+	 *    requestis the same as the current period.
+	 */
+	if (!ncfg ||
+	    ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
+	    ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
+	    ((ncfg > 1) && period_same)) {
+		/* Enable clock before writing to PWM registers. */
+		ret = clk_enable(pc->clk);
+		if (ret)
+			return ret;
+
+		if (!period_same) {
+			ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
+			if (ret)
+				goto clk_dis;
+
+			ret =
+			regmap_field_write(pc->prescale_low,
+					   prescale & PWM_PRESCALE_LOW_MASK);
+			if (ret)
+				goto clk_dis;
+
+			ret =
+			regmap_field_write(pc->prescale_high,
+				(prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
+			if (ret)
+				goto clk_dis;
+		}
+
+		/*
+		 * When PWMVal == 0, PWM pulse = 1 local clock cycle.
+		 * When PWMVal == max_pwm_count,
+		 * PWM pulse = (max_pwm_count + 1) local cycles,
+		 * that is continuous pulse: signal never goes low.
+		 */
+		pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
+
+		ret = regmap_write(pc->regmap, STI_DS_REG(pwm->hwpwm), pwmvalx);
+		if (ret)
+			goto clk_dis;
+
+		ret = regmap_field_write(pc->pwm_int_en, 0);
+
+		pc->cur = pwm;
+
+		dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
+			prescale, period_ns, duty_ns, pwmvalx);
+	} else {
+		return -EINVAL;
+	}
+
+clk_dis:
+	clk_disable(pc->clk);
+	return ret;
+}
+
+static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+	struct device *dev = pc->dev;
+	int ret = 0;
+
+	/*
+	 * Since we have a common enable for all PWM channels,
+	 * do not enable if already enabled.
+	 */
+	mutex_lock(&pc->sti_pwm_lock);
+	if (!pc->en_count) {
+		ret = clk_enable(pc->clk);
+		if (ret)
+			goto out;
+
+		ret = regmap_field_write(pc->pwm_en, 1);
+		if (ret) {
+			dev_err(dev, "failed to enable PWM device:%d\n",
+				pwm->hwpwm);
+			goto out;
+		}
+	}
+	pc->en_count++;
+out:
+	mutex_unlock(&pc->sti_pwm_lock);
+	return ret;
+}
+
+static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+
+	mutex_lock(&pc->sti_pwm_lock);
+	if (--pc->en_count) {
+		mutex_unlock(&pc->sti_pwm_lock);
+		return;
+	}
+	regmap_field_write(pc->pwm_en, 0);
+
+	clk_disable(pc->clk);
+	mutex_unlock(&pc->sti_pwm_lock);
+}
+
+static const struct pwm_ops sti_pwm_ops = {
+	.config = sti_pwm_config,
+	.enable = sti_pwm_enable,
+	.disable = sti_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
+{
+	struct device *dev = pc->dev;
+	const struct reg_field *reg_fields;
+	struct device_node *np = dev->of_node;
+	struct sti_pwm_compat_data *cdata = pc->cdata;
+	u32 num_chan;
+
+	of_property_read_u32(np, "st,pwm-num-chan", &num_chan);
+	if (num_chan)
+		cdata->num_chan = num_chan;
+
+	reg_fields = cdata->reg_fields;
+
+	pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
+					reg_fields[PWMCLK_PRESCALE_LOW]);
+	if (IS_ERR(pc->prescale_low))
+		return PTR_ERR(pc->prescale_low);
+
+	pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
+					reg_fields[PWMCLK_PRESCALE_HIGH]);
+	if (IS_ERR(pc->prescale_high))
+		return PTR_ERR(pc->prescale_high);
+
+	pc->pwm_en = devm_regmap_field_alloc(dev, pc->regmap,
+					     reg_fields[PWM_EN]);
+	if (IS_ERR(pc->pwm_en))
+		return PTR_ERR(pc->pwm_en);
+
+	pc->pwm_int_en = devm_regmap_field_alloc(dev, pc->regmap,
+						 reg_fields[PWM_INT_EN]);
+	if (IS_ERR(pc->pwm_int_en))
+		return PTR_ERR(pc->pwm_int_en);
+
+	return 0;
+}
+
+static const struct regmap_config sti_pwm_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+};
+
+static int sti_pwm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct sti_pwm_compat_data *cdata;
+	struct sti_pwm_chip *pc;
+	struct resource *res;
+	int ret;
+
+	pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
+	if (!pc)
+		return -ENOMEM;
+
+	cdata = devm_kzalloc(dev, sizeof(*cdata), GFP_KERNEL);
+	if (!cdata)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	pc->mmio = devm_ioremap_resource(dev, res);
+	if (IS_ERR(pc->mmio))
+		return PTR_ERR(pc->mmio);
+
+	pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
+					   &sti_pwm_regmap_config);
+	if (IS_ERR(pc->regmap))
+		return PTR_ERR(pc->regmap);
+
+	/*
+	 * Setup PWM data with default values: some values could be replaced
+	 * with specific ones provided from Device Tree.
+	 */
+	cdata->reg_fields   = &sti_pwm_regfields[0];
+	cdata->max_prescale = 0xff;
+	cdata->max_pwm_cnt  = 255;
+	cdata->num_chan     = 1;
+
+	pc->cdata = cdata;
+	pc->dev = dev;
+	pc->en_count = 0;
+	mutex_init(&pc->sti_pwm_lock);
+
+	ret = sti_pwm_probe_dt(pc);
+	if (ret)
+		return ret;
+
+	pc->clk = of_clk_get_by_name(dev->of_node, "pwm");
+	if (IS_ERR(pc->clk)) {
+		dev_err(dev, "failed to get PWM clock\n");
+		return PTR_ERR(pc->clk);
+	}
+
+	pc->clk_rate = clk_get_rate(pc->clk);
+	if (!pc->clk_rate) {
+		dev_err(dev, "failed to get clock rate\n");
+		return -EINVAL;
+	}
+
+	ret = clk_prepare(pc->clk);
+	if (ret) {
+		dev_err(dev, "failed to prepare clock\n");
+		return ret;
+	}
+
+	pc->chip.dev = dev;
+	pc->chip.ops = &sti_pwm_ops;
+	pc->chip.base = -1;
+	pc->chip.npwm = pc->cdata->num_chan;
+	pc->chip.can_sleep = true;
+
+	ret = pwmchip_add(&pc->chip);
+	if (ret < 0) {
+		clk_unprepare(pc->clk);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, pc);
+
+	return 0;
+}
+
+static int sti_pwm_remove(struct platform_device *pdev)
+{
+	struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
+	unsigned int i;
+
+	for (i = 0; i < pc->cdata->num_chan; i++)
+		pwm_disable(&pc->chip.pwms[i]);
+
+	clk_unprepare(pc->clk);
+
+	return pwmchip_remove(&pc->chip);
+}
+
+static const struct of_device_id sti_pwm_of_match[] = {
+	{ .compatible = "st,sti-pwm", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sti_pwm_of_match);
+
+static struct platform_driver sti_pwm_driver = {
+	.driver = {
+		.name = "sti-pwm",
+		.of_match_table = sti_pwm_of_match,
+	},
+	.probe = sti_pwm_probe,
+	.remove = sti_pwm_remove,
+};
+module_platform_driver(sti_pwm_driver);
+
+MODULE_AUTHOR("Ajit Pal Singh <[email protected]>");
+MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
+MODULE_LICENSE("GPL");