1 files changed, 340 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-bcm-kona.c b/drivers/pwm/pwm-bcm-kona.c
new file mode 100644
index 0000000000..e5b00cc9f7
--- /dev/null
+++ b/drivers/pwm/pwm-bcm-kona.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2014 Broadcom Corporation
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+/*
+ * The Kona PWM has some unusual characteristics.  Here are the main points.
+ *
+ * 1) There is no disable bit and the hardware docs advise programming a zero
+ *    duty to achieve output equivalent to that of a normal disable operation.
+ *
+ * 2) Changes to prescale, duty, period, and polarity do not take effect until
+ *    a subsequent rising edge of the trigger bit.
+ *
+ * 3) If the smooth bit and trigger bit are both low, the output is a constant
+ *    high signal.  Otherwise, the earlier waveform continues to be output.
+ *
+ * 4) If the smooth bit is set on the rising edge of the trigger bit, output
+ *    will transition to the new settings on a period boundary (which could be
+ *    seconds away).  If the smooth bit is clear, new settings will be applied
+ *    as soon as possible (the hardware always has a 400ns delay).
+ *
+ * 5) When the external clock that feeds the PWM is disabled, output is pegged
+ *    high or low depending on its state at that exact instant.
+ */
+
+#define PWM_CONTROL_OFFSET			0x00000000
+#define PWM_CONTROL_SMOOTH_SHIFT(chan)		(24 + (chan))
+#define PWM_CONTROL_TYPE_SHIFT(chan)		(16 + (chan))
+#define PWM_CONTROL_POLARITY_SHIFT(chan)	(8 + (chan))
+#define PWM_CONTROL_TRIGGER_SHIFT(chan)		(chan)
+
+#define PRESCALE_OFFSET				0x00000004
+#define PRESCALE_SHIFT(chan)			((chan) << 2)
+#define PRESCALE_MASK(chan)			(0x7 << PRESCALE_SHIFT(chan))
+#define PRESCALE_MIN				0x00000000
+#define PRESCALE_MAX				0x00000007
+
+#define PERIOD_COUNT_OFFSET(chan)		(0x00000008 + ((chan) << 3))
+#define PERIOD_COUNT_MIN			0x00000002
+#define PERIOD_COUNT_MAX			0x00ffffff
+
+#define DUTY_CYCLE_HIGH_OFFSET(chan)		(0x0000000c + ((chan) << 3))
+#define DUTY_CYCLE_HIGH_MIN			0x00000000
+#define DUTY_CYCLE_HIGH_MAX			0x00ffffff
+
+struct kona_pwmc {
+	struct pwm_chip chip;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static inline struct kona_pwmc *to_kona_pwmc(struct pwm_chip *chip)
+{
+	return container_of(chip, struct kona_pwmc, chip);
+}
+
+/*
+ * Clear trigger bit but set smooth bit to maintain old output.
+ */
+static void kona_pwmc_prepare_for_settings(struct kona_pwmc *kp,
+	unsigned int chan)
+{
+	unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
+
+	value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan);
+	value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan));
+	writel(value, kp->base + PWM_CONTROL_OFFSET);
+
+	/*
+	 * There must be a min 400ns delay between clearing trigger and setting
+	 * it. Failing to do this may result in no PWM signal.
+	 */
+	ndelay(400);
+}
+
+static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan)
+{
+	unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
+
+	/* Set trigger bit and clear smooth bit to apply new settings */
+	value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan));
+	value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan);
+	writel(value, kp->base + PWM_CONTROL_OFFSET);
+
+	/* Trigger bit must be held high for at least 400 ns. */
+	ndelay(400);
+}
+
+static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			    u64 duty_ns, u64 period_ns)
+{
+	struct kona_pwmc *kp = to_kona_pwmc(chip);
+	u64 div, rate;
+	unsigned long prescale = PRESCALE_MIN, pc, dc;
+	unsigned int value, chan = pwm->hwpwm;
+
+	/*
+	 * Find period count, duty count and prescale to suit duty_ns and
+	 * period_ns. This is done according to formulas described below:
+	 *
+	 * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE
+	 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
+	 *
+	 * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
+	 * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
+	 */
+
+	rate = clk_get_rate(kp->clk);
+
+	while (1) {
+		div = 1000000000;
+		div *= 1 + prescale;
+		pc = mul_u64_u64_div_u64(rate, period_ns, div);
+		dc = mul_u64_u64_div_u64(rate, duty_ns, div);
+
+		/* If duty_ns or period_ns are not achievable then return */
+		if (pc < PERIOD_COUNT_MIN)
+			return -EINVAL;
+
+		/* If pc and dc are in bounds, the calculation is done */
+		if (pc <= PERIOD_COUNT_MAX && dc <= DUTY_CYCLE_HIGH_MAX)
+			break;
+
+		/* Otherwise, increase prescale and recalculate pc and dc */
+		if (++prescale > PRESCALE_MAX)
+			return -EINVAL;
+	}
+
+	kona_pwmc_prepare_for_settings(kp, chan);
+
+	value = readl(kp->base + PRESCALE_OFFSET);
+	value &= ~PRESCALE_MASK(chan);
+	value |= prescale << PRESCALE_SHIFT(chan);
+	writel(value, kp->base + PRESCALE_OFFSET);
+
+	writel(pc, kp->base + PERIOD_COUNT_OFFSET(chan));
+
+	writel(dc, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
+
+	kona_pwmc_apply_settings(kp, chan);
+
+	return 0;
+}
+
+static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+				  enum pwm_polarity polarity)
+{
+	struct kona_pwmc *kp = to_kona_pwmc(chip);
+	unsigned int chan = pwm->hwpwm;
+	unsigned int value;
+	int ret;
+
+	ret = clk_prepare_enable(kp->clk);
+	if (ret < 0) {
+		dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+		return ret;
+	}
+
+	kona_pwmc_prepare_for_settings(kp, chan);
+
+	value = readl(kp->base + PWM_CONTROL_OFFSET);
+
+	if (polarity == PWM_POLARITY_NORMAL)
+		value |= 1 << PWM_CONTROL_POLARITY_SHIFT(chan);
+	else
+		value &= ~(1 << PWM_CONTROL_POLARITY_SHIFT(chan));
+
+	writel(value, kp->base + PWM_CONTROL_OFFSET);
+
+	kona_pwmc_apply_settings(kp, chan);
+
+	clk_disable_unprepare(kp->clk);
+
+	return 0;
+}
+
+static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct kona_pwmc *kp = to_kona_pwmc(chip);
+	int ret;
+
+	ret = clk_prepare_enable(kp->clk);
+	if (ret < 0) {
+		dev_err(chip->dev, "failed to enable clock: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct kona_pwmc *kp = to_kona_pwmc(chip);
+	unsigned int chan = pwm->hwpwm;
+	unsigned int value;
+
+	kona_pwmc_prepare_for_settings(kp, chan);
+
+	/* Simulate a disable by configuring for zero duty */
+	writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
+	writel(0, kp->base + PERIOD_COUNT_OFFSET(chan));
+
+	/* Set prescale to 0 for this channel */
+	value = readl(kp->base + PRESCALE_OFFSET);
+	value &= ~PRESCALE_MASK(chan);
+	writel(value, kp->base + PRESCALE_OFFSET);
+
+	kona_pwmc_apply_settings(kp, chan);
+
+	clk_disable_unprepare(kp->clk);
+}
+
+static int kona_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			   const struct pwm_state *state)
+{
+	int err;
+	struct kona_pwmc *kp = to_kona_pwmc(chip);
+	bool enabled = pwm->state.enabled;
+
+	if (state->polarity != pwm->state.polarity) {
+		if (enabled) {
+			kona_pwmc_disable(chip, pwm);
+			enabled = false;
+		}
+
+		err = kona_pwmc_set_polarity(chip, pwm, state->polarity);
+		if (err)
+			return err;
+
+		pwm->state.polarity = state->polarity;
+	}
+
+	if (!state->enabled) {
+		if (enabled)
+			kona_pwmc_disable(chip, pwm);
+		return 0;
+	} else if (!enabled) {
+		/*
+		 * This is a bit special here, usually the PWM should only be
+		 * enabled when duty and period are setup. But before this
+		 * driver was converted to .apply it was done the other way
+		 * around and so this behaviour was kept even though this might
+		 * result in a glitch. This might be improvable by someone with
+		 * hardware and/or documentation.
+		 */
+		err = kona_pwmc_enable(chip, pwm);
+		if (err)
+			return err;
+	}
+
+	err = kona_pwmc_config(pwm->chip, pwm, state->duty_cycle, state->period);
+	if (err && !pwm->state.enabled)
+		clk_disable_unprepare(kp->clk);
+
+	return err;
+}
+
+static const struct pwm_ops kona_pwm_ops = {
+	.apply = kona_pwmc_apply,
+	.owner = THIS_MODULE,
+};
+
+static int kona_pwmc_probe(struct platform_device *pdev)
+{
+	struct kona_pwmc *kp;
+	unsigned int chan;
+	unsigned int value = 0;
+	int ret = 0;
+
+	kp = devm_kzalloc(&pdev->dev, sizeof(*kp), GFP_KERNEL);
+	if (kp == NULL)
+		return -ENOMEM;
+
+	kp->chip.dev = &pdev->dev;
+	kp->chip.ops = &kona_pwm_ops;
+	kp->chip.npwm = 6;
+
+	kp->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(kp->base))
+		return PTR_ERR(kp->base);
+
+	kp->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(kp->clk)) {
+		dev_err(&pdev->dev, "failed to get clock: %ld\n",
+			PTR_ERR(kp->clk));
+		return PTR_ERR(kp->clk);
+	}
+
+	ret = clk_prepare_enable(kp->clk);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
+		return ret;
+	}
+
+	/* Set push/pull for all channels */
+	for (chan = 0; chan < kp->chip.npwm; chan++)
+		value |= (1 << PWM_CONTROL_TYPE_SHIFT(chan));
+
+	writel(value, kp->base + PWM_CONTROL_OFFSET);
+
+	clk_disable_unprepare(kp->clk);
+
+	ret = devm_pwmchip_add(&pdev->dev, &kp->chip);
+	if (ret < 0)
+		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
+
+	return ret;
+}
+
+static const struct of_device_id bcm_kona_pwmc_dt[] = {
+	{ .compatible = "brcm,kona-pwm" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, bcm_kona_pwmc_dt);
+
+static struct platform_driver kona_pwmc_driver = {
+	.driver = {
+		.name = "bcm-kona-pwm",
+		.of_match_table = bcm_kona_pwmc_dt,
+	},
+	.probe = kona_pwmc_probe,
+};
+module_platform_driver(kona_pwmc_driver);
+
+MODULE_AUTHOR("Broadcom Corporation <bcm-kernel-feedback-list@broadcom.com>");
+MODULE_AUTHOR("Tim Kryger <tkryger@broadcom.com>");
+MODULE_DESCRIPTION("Broadcom Kona PWM driver");
+MODULE_LICENSE("GPL v2");