1 files changed, 559 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
new file mode 100644
index 0000000000..1f73325d1b
--- /dev/null
+++ b/drivers/pwm/pwm-atmel.c
@@ -0,0 +1,559 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for Atmel Pulse Width Modulation Controller
+ *
+ * Copyright (C) 2013 Atmel Corporation
+ *		 Bo Shen <voice.shen@atmel.com>
+ *
+ * Links to reference manuals for the supported PWM chips can be found in
+ * Documentation/arch/arm/microchip.rst.
+ *
+ * Limitations:
+ * - Periods start with the inactive level.
+ * - Hardware has to be stopped in general to update settings.
+ *
+ * Software bugs/possible improvements:
+ * - When atmel_pwm_apply() is called with state->enabled=false a change in
+ *   state->polarity isn't honored.
+ * - Instead of sleeping to wait for a completed period, the interrupt
+ *   functionality could be used.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+/* The following is global registers for PWM controller */
+#define PWM_ENA			0x04
+#define PWM_DIS			0x08
+#define PWM_SR			0x0C
+#define PWM_ISR			0x1C
+/* Bit field in SR */
+#define PWM_SR_ALL_CH_MASK	0x0F
+
+/* The following register is PWM channel related registers */
+#define PWM_CH_REG_OFFSET	0x200
+#define PWM_CH_REG_SIZE		0x20
+
+#define PWM_CMR			0x0
+/* Bit field in CMR */
+#define PWM_CMR_CPOL		(1 << 9)
+#define PWM_CMR_UPD_CDTY	(1 << 10)
+#define PWM_CMR_CPRE_MSK	0xF
+
+/* The following registers for PWM v1 */
+#define PWMV1_CDTY		0x04
+#define PWMV1_CPRD		0x08
+#define PWMV1_CUPD		0x10
+
+/* The following registers for PWM v2 */
+#define PWMV2_CDTY		0x04
+#define PWMV2_CDTYUPD		0x08
+#define PWMV2_CPRD		0x0C
+#define PWMV2_CPRDUPD		0x10
+
+#define PWM_MAX_PRES		10
+
+struct atmel_pwm_registers {
+	u8 period;
+	u8 period_upd;
+	u8 duty;
+	u8 duty_upd;
+};
+
+struct atmel_pwm_config {
+	u32 period_bits;
+};
+
+struct atmel_pwm_data {
+	struct atmel_pwm_registers regs;
+	struct atmel_pwm_config cfg;
+};
+
+struct atmel_pwm_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	void __iomem *base;
+	const struct atmel_pwm_data *data;
+
+	/*
+	 * The hardware supports a mechanism to update a channel's duty cycle at
+	 * the end of the currently running period. When such an update is
+	 * pending we delay disabling the PWM until the new configuration is
+	 * active because otherwise pmw_config(duty_cycle=0); pwm_disable();
+	 * might not result in an inactive output.
+	 * This bitmask tracks for which channels an update is pending in
+	 * hardware.
+	 */
+	u32 update_pending;
+
+	/* Protects .update_pending */
+	spinlock_t lock;
+};
+
+static inline struct atmel_pwm_chip *to_atmel_pwm_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct atmel_pwm_chip, chip);
+}
+
+static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip,
+				  unsigned long offset)
+{
+	return readl_relaxed(chip->base + offset);
+}
+
+static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip,
+				    unsigned long offset, unsigned long val)
+{
+	writel_relaxed(val, chip->base + offset);
+}
+
+static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip,
+				     unsigned int ch, unsigned long offset)
+{
+	unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE;
+
+	return atmel_pwm_readl(chip, base + offset);
+}
+
+static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip,
+				       unsigned int ch, unsigned long offset,
+				       unsigned long val)
+{
+	unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE;
+
+	atmel_pwm_writel(chip, base + offset, val);
+}
+
+static void atmel_pwm_update_pending(struct atmel_pwm_chip *chip)
+{
+	/*
+	 * Each channel that has its bit in ISR set started a new period since
+	 * ISR was cleared and so there is no more update pending.  Note that
+	 * reading ISR clears it, so this needs to handle all channels to not
+	 * loose information.
+	 */
+	u32 isr = atmel_pwm_readl(chip, PWM_ISR);
+
+	chip->update_pending &= ~isr;
+}
+
+static void atmel_pwm_set_pending(struct atmel_pwm_chip *chip, unsigned int ch)
+{
+	spin_lock(&chip->lock);
+
+	/*
+	 * Clear pending flags in hardware because otherwise there might still
+	 * be a stale flag in ISR.
+	 */
+	atmel_pwm_update_pending(chip);
+
+	chip->update_pending |= (1 << ch);
+
+	spin_unlock(&chip->lock);
+}
+
+static int atmel_pwm_test_pending(struct atmel_pwm_chip *chip, unsigned int ch)
+{
+	int ret = 0;
+
+	spin_lock(&chip->lock);
+
+	if (chip->update_pending & (1 << ch)) {
+		atmel_pwm_update_pending(chip);
+
+		if (chip->update_pending & (1 << ch))
+			ret = 1;
+	}
+
+	spin_unlock(&chip->lock);
+
+	return ret;
+}
+
+static int atmel_pwm_wait_nonpending(struct atmel_pwm_chip *chip, unsigned int ch)
+{
+	unsigned long timeout = jiffies + 2 * HZ;
+	int ret;
+
+	while ((ret = atmel_pwm_test_pending(chip, ch)) &&
+	       time_before(jiffies, timeout))
+		usleep_range(10, 100);
+
+	return ret ? -ETIMEDOUT : 0;
+}
+
+static int atmel_pwm_calculate_cprd_and_pres(struct pwm_chip *chip,
+					     unsigned long clkrate,
+					     const struct pwm_state *state,
+					     unsigned long *cprd, u32 *pres)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	unsigned long long cycles = state->period;
+	int shift;
+
+	/* Calculate the period cycles and prescale value */
+	cycles *= clkrate;
+	do_div(cycles, NSEC_PER_SEC);
+
+	/*
+	 * The register for the period length is cfg.period_bits bits wide.
+	 * So for each bit the number of clock cycles is wider divide the input
+	 * clock frequency by two using pres and shift cprd accordingly.
+	 */
+	shift = fls(cycles) - atmel_pwm->data->cfg.period_bits;
+
+	if (shift > PWM_MAX_PRES) {
+		dev_err(chip->dev, "pres exceeds the maximum value\n");
+		return -EINVAL;
+	} else if (shift > 0) {
+		*pres = shift;
+		cycles >>= *pres;
+	} else {
+		*pres = 0;
+	}
+
+	*cprd = cycles;
+
+	return 0;
+}
+
+static void atmel_pwm_calculate_cdty(const struct pwm_state *state,
+				     unsigned long clkrate, unsigned long cprd,
+				     u32 pres, unsigned long *cdty)
+{
+	unsigned long long cycles = state->duty_cycle;
+
+	cycles *= clkrate;
+	do_div(cycles, NSEC_PER_SEC);
+	cycles >>= pres;
+	*cdty = cprd - cycles;
+}
+
+static void atmel_pwm_update_cdty(struct pwm_chip *chip, struct pwm_device *pwm,
+				  unsigned long cdty)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	u32 val;
+
+	if (atmel_pwm->data->regs.duty_upd ==
+	    atmel_pwm->data->regs.period_upd) {
+		val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
+		val &= ~PWM_CMR_UPD_CDTY;
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
+	}
+
+	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
+			    atmel_pwm->data->regs.duty_upd, cdty);
+	atmel_pwm_set_pending(atmel_pwm, pwm->hwpwm);
+}
+
+static void atmel_pwm_set_cprd_cdty(struct pwm_chip *chip,
+				    struct pwm_device *pwm,
+				    unsigned long cprd, unsigned long cdty)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+
+	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
+			    atmel_pwm->data->regs.duty, cdty);
+	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
+			    atmel_pwm->data->regs.period, cprd);
+}
+
+static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm,
+			      bool disable_clk)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	unsigned long timeout;
+
+	atmel_pwm_wait_nonpending(atmel_pwm, pwm->hwpwm);
+
+	atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
+
+	/*
+	 * Wait for the PWM channel disable operation to be effective before
+	 * stopping the clock.
+	 */
+	timeout = jiffies + 2 * HZ;
+
+	while ((atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm)) &&
+	       time_before(jiffies, timeout))
+		usleep_range(10, 100);
+
+	if (disable_clk)
+		clk_disable(atmel_pwm->clk);
+}
+
+static int atmel_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			   const struct pwm_state *state)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	struct pwm_state cstate;
+	unsigned long cprd, cdty;
+	u32 pres, val;
+	int ret;
+
+	pwm_get_state(pwm, &cstate);
+
+	if (state->enabled) {
+		unsigned long clkrate = clk_get_rate(atmel_pwm->clk);
+
+		if (cstate.enabled &&
+		    cstate.polarity == state->polarity &&
+		    cstate.period == state->period) {
+			u32 cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
+
+			cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
+						  atmel_pwm->data->regs.period);
+			pres = cmr & PWM_CMR_CPRE_MSK;
+
+			atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty);
+			atmel_pwm_update_cdty(chip, pwm, cdty);
+			return 0;
+		}
+
+		ret = atmel_pwm_calculate_cprd_and_pres(chip, clkrate, state, &cprd,
+							&pres);
+		if (ret) {
+			dev_err(chip->dev,
+				"failed to calculate cprd and prescaler\n");
+			return ret;
+		}
+
+		atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty);
+
+		if (cstate.enabled) {
+			atmel_pwm_disable(chip, pwm, false);
+		} else {
+			ret = clk_enable(atmel_pwm->clk);
+			if (ret) {
+				dev_err(chip->dev, "failed to enable clock\n");
+				return ret;
+			}
+		}
+
+		/* It is necessary to preserve CPOL, inside CMR */
+		val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
+		val = (val & ~PWM_CMR_CPRE_MSK) | (pres & PWM_CMR_CPRE_MSK);
+		if (state->polarity == PWM_POLARITY_NORMAL)
+			val &= ~PWM_CMR_CPOL;
+		else
+			val |= PWM_CMR_CPOL;
+		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
+		atmel_pwm_set_cprd_cdty(chip, pwm, cprd, cdty);
+		atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
+	} else if (cstate.enabled) {
+		atmel_pwm_disable(chip, pwm, true);
+	}
+
+	return 0;
+}
+
+static int atmel_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			       struct pwm_state *state)
+{
+	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
+	u32 sr, cmr;
+
+	sr = atmel_pwm_readl(atmel_pwm, PWM_SR);
+	cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
+
+	if (sr & (1 << pwm->hwpwm)) {
+		unsigned long rate = clk_get_rate(atmel_pwm->clk);
+		u32 cdty, cprd, pres;
+		u64 tmp;
+
+		pres = cmr & PWM_CMR_CPRE_MSK;
+
+		cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
+					  atmel_pwm->data->regs.period);
+		tmp = (u64)cprd * NSEC_PER_SEC;
+		tmp <<= pres;
+		state->period = DIV64_U64_ROUND_UP(tmp, rate);
+
+		/* Wait for an updated duty_cycle queued in hardware */
+		atmel_pwm_wait_nonpending(atmel_pwm, pwm->hwpwm);
+
+		cdty = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
+					  atmel_pwm->data->regs.duty);
+		tmp = (u64)(cprd - cdty) * NSEC_PER_SEC;
+		tmp <<= pres;
+		state->duty_cycle = DIV64_U64_ROUND_UP(tmp, rate);
+
+		state->enabled = true;
+	} else {
+		state->enabled = false;
+	}
+
+	if (cmr & PWM_CMR_CPOL)
+		state->polarity = PWM_POLARITY_INVERSED;
+	else
+		state->polarity = PWM_POLARITY_NORMAL;
+
+	return 0;
+}
+
+static const struct pwm_ops atmel_pwm_ops = {
+	.apply = atmel_pwm_apply,
+	.get_state = atmel_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
+static const struct atmel_pwm_data atmel_sam9rl_pwm_data = {
+	.regs = {
+		.period		= PWMV1_CPRD,
+		.period_upd	= PWMV1_CUPD,
+		.duty		= PWMV1_CDTY,
+		.duty_upd	= PWMV1_CUPD,
+	},
+	.cfg = {
+		/* 16 bits to keep period and duty. */
+		.period_bits	= 16,
+	},
+};
+
+static const struct atmel_pwm_data atmel_sama5_pwm_data = {
+	.regs = {
+		.period		= PWMV2_CPRD,
+		.period_upd	= PWMV2_CPRDUPD,
+		.duty		= PWMV2_CDTY,
+		.duty_upd	= PWMV2_CDTYUPD,
+	},
+	.cfg = {
+		/* 16 bits to keep period and duty. */
+		.period_bits	= 16,
+	},
+};
+
+static const struct atmel_pwm_data mchp_sam9x60_pwm_data = {
+	.regs = {
+		.period		= PWMV1_CPRD,
+		.period_upd	= PWMV1_CUPD,
+		.duty		= PWMV1_CDTY,
+		.duty_upd	= PWMV1_CUPD,
+	},
+	.cfg = {
+		/* 32 bits to keep period and duty. */
+		.period_bits	= 32,
+	},
+};
+
+static const struct of_device_id atmel_pwm_dt_ids[] = {
+	{
+		.compatible = "atmel,at91sam9rl-pwm",
+		.data = &atmel_sam9rl_pwm_data,
+	}, {
+		.compatible = "atmel,sama5d3-pwm",
+		.data = &atmel_sama5_pwm_data,
+	}, {
+		.compatible = "atmel,sama5d2-pwm",
+		.data = &atmel_sama5_pwm_data,
+	}, {
+		.compatible = "microchip,sam9x60-pwm",
+		.data = &mchp_sam9x60_pwm_data,
+	}, {
+		/* sentinel */
+	},
+};
+MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
+
+static int atmel_pwm_enable_clk_if_on(struct atmel_pwm_chip *atmel_pwm, bool on)
+{
+	unsigned int i, cnt = 0;
+	unsigned long sr;
+	int ret = 0;
+
+	sr = atmel_pwm_readl(atmel_pwm, PWM_SR) & PWM_SR_ALL_CH_MASK;
+	if (!sr)
+		return 0;
+
+	cnt = bitmap_weight(&sr, atmel_pwm->chip.npwm);
+
+	if (!on)
+		goto disable_clk;
+
+	for (i = 0; i < cnt; i++) {
+		ret = clk_enable(atmel_pwm->clk);
+		if (ret) {
+			dev_err(atmel_pwm->chip.dev,
+				"failed to enable clock for pwm %pe\n",
+				ERR_PTR(ret));
+
+			cnt = i;
+			goto disable_clk;
+		}
+	}
+
+	return 0;
+
+disable_clk:
+	while (cnt--)
+		clk_disable(atmel_pwm->clk);
+
+	return ret;
+}
+
+static int atmel_pwm_probe(struct platform_device *pdev)
+{
+	struct atmel_pwm_chip *atmel_pwm;
+	int ret;
+
+	atmel_pwm = devm_kzalloc(&pdev->dev, sizeof(*atmel_pwm), GFP_KERNEL);
+	if (!atmel_pwm)
+		return -ENOMEM;
+
+	atmel_pwm->data = of_device_get_match_data(&pdev->dev);
+
+	atmel_pwm->update_pending = 0;
+	spin_lock_init(&atmel_pwm->lock);
+
+	atmel_pwm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(atmel_pwm->base))
+		return PTR_ERR(atmel_pwm->base);
+
+	atmel_pwm->clk = devm_clk_get_prepared(&pdev->dev, NULL);
+	if (IS_ERR(atmel_pwm->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(atmel_pwm->clk),
+				     "failed to get prepared PWM clock\n");
+
+	atmel_pwm->chip.dev = &pdev->dev;
+	atmel_pwm->chip.ops = &atmel_pwm_ops;
+	atmel_pwm->chip.npwm = 4;
+
+	ret = atmel_pwm_enable_clk_if_on(atmel_pwm, true);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_pwmchip_add(&pdev->dev, &atmel_pwm->chip);
+	if (ret < 0) {
+		dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n");
+		goto disable_clk;
+	}
+
+	return 0;
+
+disable_clk:
+	atmel_pwm_enable_clk_if_on(atmel_pwm, false);
+
+	return ret;
+}
+
+static struct platform_driver atmel_pwm_driver = {
+	.driver = {
+		.name = "atmel-pwm",
+		.of_match_table = of_match_ptr(atmel_pwm_dt_ids),
+	},
+	.probe = atmel_pwm_probe,
+};
+module_platform_driver(atmel_pwm_driver);
+
+MODULE_ALIAS("platform:atmel-pwm");
+MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>");
+MODULE_DESCRIPTION("Atmel PWM driver");
+MODULE_LICENSE("GPL v2");