Merge tag 'pwm/for-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm

Pull pwm updates from Thierry Reding:
 "This set of changes contains a new driver for SiFive SoCs as well as
  enhancements to the core (device links are used to track dependencies
  between PWM providers and consumers, support for PWM controllers via
  ACPI, sysfs will now suspend/resume PWMs that it has claimed) and
  various existing drivers"

* tag 'pwm/for-5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: (37 commits)
  pwm: fsl-ftm: Make sure to unlock mutex on failure
  pwm: fsl-ftm: Use write protection for prescaler & polarity
  pwm: fsl-ftm: More relaxed permissions for updating period
  pwm: atmel-hlcdc: Add compatible for SAM9X60 HLCDC's PWM
  pwm: bcm2835: Improve precision of PWM
  leds: pwm: Support ACPI via firmware-node framework
  pwm: Add support referencing PWMs from ACPI
  pwm: rcar: Remove suspend/resume support
  pwm: sysfs: Add suspend/resume support
  pwm: Add power management descriptions
  pwm: meson: Add documentation to the driver
  pwm: meson: Add support PWM_POLARITY_INVERSED when disabling
  pwm: meson: Don't cache struct pwm_state internally
  pwm: meson: Read the full hardware state in meson_pwm_get_state()
  pwm: meson: Simplify the calculation of the pre-divider and count
  pwm: meson: Move pwm_set_chip_data() to meson_pwm_request()
  pwm: meson: Add the per-channel register offsets and bits in a struct
  pwm: meson: Add the meson_pwm_channel data to struct meson_pwm
  pwm: meson: Pass struct pwm_device to meson_pwm_calc()
  pwm: meson: Don't duplicate the polarity internally
  ...

1 files changed, 339 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
new file mode 100644
index 000000000000..a7c107f19e66
--- /dev/null
+++ b/drivers/pwm/pwm-sifive.c
@@ -0,0 +1,339 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017-2018 SiFive
+ * For SiFive's PWM IP block documentation please refer Chapter 14 of
+ * Reference Manual : https://static.dev.sifive.com/FU540-C000-v1.0.pdf
+ *
+ * Limitations:
+ * - When changing both duty cycle and period, we cannot prevent in
+ *   software that the output might produce a period with mixed
+ *   settings (new period length and old duty cycle).
+ * - The hardware cannot generate a 100% duty cycle.
+ * - The hardware generates only inverted output.
+ */
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+#include <linux/bitfield.h>
+
+/* Register offsets */
+#define PWM_SIFIVE_PWMCFG		0x0
+#define PWM_SIFIVE_PWMCOUNT		0x8
+#define PWM_SIFIVE_PWMS			0x10
+#define PWM_SIFIVE_PWMCMP0		0x20
+
+/* PWMCFG fields */
+#define PWM_SIFIVE_PWMCFG_SCALE		GENMASK(3, 0)
+#define PWM_SIFIVE_PWMCFG_STICKY	BIT(8)
+#define PWM_SIFIVE_PWMCFG_ZERO_CMP	BIT(9)
+#define PWM_SIFIVE_PWMCFG_DEGLITCH	BIT(10)
+#define PWM_SIFIVE_PWMCFG_EN_ALWAYS	BIT(12)
+#define PWM_SIFIVE_PWMCFG_EN_ONCE	BIT(13)
+#define PWM_SIFIVE_PWMCFG_CENTER	BIT(16)
+#define PWM_SIFIVE_PWMCFG_GANG		BIT(24)
+#define PWM_SIFIVE_PWMCFG_IP		BIT(28)
+
+/* PWM_SIFIVE_SIZE_PWMCMP is used to calculate offset for pwmcmpX registers */
+#define PWM_SIFIVE_SIZE_PWMCMP		4
+#define PWM_SIFIVE_CMPWIDTH		16
+#define PWM_SIFIVE_DEFAULT_PERIOD	10000000
+
+struct pwm_sifive_ddata {
+	struct pwm_chip	chip;
+	struct mutex lock; /* lock to protect user_count */
+	struct notifier_block notifier;
+	struct clk *clk;
+	void __iomem *regs;
+	unsigned int real_period;
+	unsigned int approx_period;
+	int user_count;
+};
+
+static inline
+struct pwm_sifive_ddata *pwm_sifive_chip_to_ddata(struct pwm_chip *c)
+{
+	return container_of(c, struct pwm_sifive_ddata, chip);
+}
+
+static int pwm_sifive_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
+
+	mutex_lock(&ddata->lock);
+	ddata->user_count++;
+	mutex_unlock(&ddata->lock);
+
+	return 0;
+}
+
+static void pwm_sifive_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
+
+	mutex_lock(&ddata->lock);
+	ddata->user_count--;
+	mutex_unlock(&ddata->lock);
+}
+
+static void pwm_sifive_update_clock(struct pwm_sifive_ddata *ddata,
+				    unsigned long rate)
+{
+	unsigned long long num;
+	unsigned long scale_pow;
+	int scale;
+	u32 val;
+	/*
+	 * The PWM unit is used with pwmzerocmp=0, so the only way to modify the
+	 * period length is using pwmscale which provides the number of bits the
+	 * counter is shifted before being feed to the comparators. A period
+	 * lasts (1 << (PWM_SIFIVE_CMPWIDTH + pwmscale)) clock ticks.
+	 * (1 << (PWM_SIFIVE_CMPWIDTH + scale)) * 10^9/rate = period
+	 */
+	scale_pow = div64_ul(ddata->approx_period * (u64)rate, NSEC_PER_SEC);
+	scale = clamp(ilog2(scale_pow) - PWM_SIFIVE_CMPWIDTH, 0, 0xf);
+
+	val = PWM_SIFIVE_PWMCFG_EN_ALWAYS |
+	      FIELD_PREP(PWM_SIFIVE_PWMCFG_SCALE, scale);
+	writel(val, ddata->regs + PWM_SIFIVE_PWMCFG);
+
+	/* As scale <= 15 the shift operation cannot overflow. */
+	num = (unsigned long long)NSEC_PER_SEC << (PWM_SIFIVE_CMPWIDTH + scale);
+	ddata->real_period = div64_ul(num, rate);
+	dev_dbg(ddata->chip.dev,
+		"New real_period = %u ns\n", ddata->real_period);
+}
+
+static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				 struct pwm_state *state)
+{
+	struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
+	u32 duty, val;
+
+	duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP0 +
+		     pwm->hwpwm * PWM_SIFIVE_SIZE_PWMCMP);
+
+	state->enabled = duty > 0;
+
+	val = readl(ddata->regs + PWM_SIFIVE_PWMCFG);
+	if (!(val & PWM_SIFIVE_PWMCFG_EN_ALWAYS))
+		state->enabled = false;
+
+	state->period = ddata->real_period;
+	state->duty_cycle =
+		(u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH;
+	state->polarity = PWM_POLARITY_INVERSED;
+}
+
+static int pwm_sifive_enable(struct pwm_chip *chip, bool enable)
+{
+	struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
+	int ret;
+
+	if (enable) {
+		ret = clk_enable(ddata->clk);
+		if (ret) {
+			dev_err(ddata->chip.dev, "Enable clk failed\n");
+			return ret;
+		}
+	}
+
+	if (!enable)
+		clk_disable(ddata->clk);
+
+	return 0;
+}
+
+static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			    struct pwm_state *state)
+{
+	struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
+	struct pwm_state cur_state;
+	unsigned int duty_cycle;
+	unsigned long long num;
+	bool enabled;
+	int ret = 0;
+	u32 frac;
+
+	if (state->polarity != PWM_POLARITY_INVERSED)
+		return -EINVAL;
+
+	ret = clk_enable(ddata->clk);
+	if (ret) {
+		dev_err(ddata->chip.dev, "Enable clk failed\n");
+		return ret;
+	}
+
+	mutex_lock(&ddata->lock);
+	cur_state = pwm->state;
+	enabled = cur_state.enabled;
+
+	duty_cycle = state->duty_cycle;
+	if (!state->enabled)
+		duty_cycle = 0;
+
+	/*
+	 * The problem of output producing mixed setting as mentioned at top,
+	 * occurs here. To minimize the window for this problem, we are
+	 * calculating the register values first and then writing them
+	 * consecutively
+	 */
+	num = (u64)duty_cycle * (1U << PWM_SIFIVE_CMPWIDTH);
+	frac = DIV_ROUND_CLOSEST_ULL(num, state->period);
+	/* The hardware cannot generate a 100% duty cycle */
+	frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
+
+	if (state->period != ddata->approx_period) {
+		if (ddata->user_count != 1) {
+			ret = -EBUSY;
+			goto exit;
+		}
+		ddata->approx_period = state->period;
+		pwm_sifive_update_clock(ddata, clk_get_rate(ddata->clk));
+	}
+
+	writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP0 +
+	       pwm->hwpwm * PWM_SIFIVE_SIZE_PWMCMP);
+
+	if (state->enabled != enabled)
+		pwm_sifive_enable(chip, state->enabled);
+
+exit:
+	clk_disable(ddata->clk);
+	mutex_unlock(&ddata->lock);
+	return ret;
+}
+
+static const struct pwm_ops pwm_sifive_ops = {
+	.request = pwm_sifive_request,
+	.free = pwm_sifive_free,
+	.get_state = pwm_sifive_get_state,
+	.apply = pwm_sifive_apply,
+	.owner = THIS_MODULE,
+};
+
+static int pwm_sifive_clock_notifier(struct notifier_block *nb,
+				     unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct pwm_sifive_ddata *ddata =
+		container_of(nb, struct pwm_sifive_ddata, notifier);
+
+	if (event == POST_RATE_CHANGE)
+		pwm_sifive_update_clock(ddata, ndata->new_rate);
+
+	return NOTIFY_OK;
+}
+
+static int pwm_sifive_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct pwm_sifive_ddata *ddata;
+	struct pwm_chip *chip;
+	struct resource *res;
+	int ret;
+
+	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	mutex_init(&ddata->lock);
+	chip = &ddata->chip;
+	chip->dev = dev;
+	chip->ops = &pwm_sifive_ops;
+	chip->of_xlate = of_pwm_xlate_with_flags;
+	chip->of_pwm_n_cells = 3;
+	chip->base = -1;
+	chip->npwm = 4;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ddata->regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(ddata->regs)) {
+		dev_err(dev, "Unable to map IO resources\n");
+		return PTR_ERR(ddata->regs);
+	}
+
+	ddata->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(ddata->clk)) {
+		if (PTR_ERR(ddata->clk) != -EPROBE_DEFER)
+			dev_err(dev, "Unable to find controller clock\n");
+		return PTR_ERR(ddata->clk);
+	}
+
+	ret = clk_prepare_enable(ddata->clk);
+	if (ret) {
+		dev_err(dev, "failed to enable clock for pwm: %d\n", ret);
+		return ret;
+	}
+
+	/* Watch for changes to underlying clock frequency */
+	ddata->notifier.notifier_call = pwm_sifive_clock_notifier;
+	ret = clk_notifier_register(ddata->clk, &ddata->notifier);
+	if (ret) {
+		dev_err(dev, "failed to register clock notifier: %d\n", ret);
+		goto disable_clk;
+	}
+
+	ret = pwmchip_add(chip);
+	if (ret < 0) {
+		dev_err(dev, "cannot register PWM: %d\n", ret);
+		goto unregister_clk;
+	}
+
+	platform_set_drvdata(pdev, ddata);
+	dev_dbg(dev, "SiFive PWM chip registered %d PWMs\n", chip->npwm);
+
+	return 0;
+
+unregister_clk:
+	clk_notifier_unregister(ddata->clk, &ddata->notifier);
+disable_clk:
+	clk_disable_unprepare(ddata->clk);
+
+	return ret;
+}
+
+static int pwm_sifive_remove(struct platform_device *dev)
+{
+	struct pwm_sifive_ddata *ddata = platform_get_drvdata(dev);
+	bool is_enabled = false;
+	struct pwm_device *pwm;
+	int ret, ch;
+
+	for (ch = 0; ch < ddata->chip.npwm; ch++) {
+		pwm = &ddata->chip.pwms[ch];
+		if (pwm->state.enabled) {
+			is_enabled = true;
+			break;
+		}
+	}
+	if (is_enabled)
+		clk_disable(ddata->clk);
+
+	clk_disable_unprepare(ddata->clk);
+	ret = pwmchip_remove(&ddata->chip);
+	clk_notifier_unregister(ddata->clk, &ddata->notifier);
+
+	return ret;
+}
+
+static const struct of_device_id pwm_sifive_of_match[] = {
+	{ .compatible = "sifive,pwm0" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, pwm_sifive_of_match);
+
+static struct platform_driver pwm_sifive_driver = {
+	.probe = pwm_sifive_probe,
+	.remove = pwm_sifive_remove,
+	.driver = {
+		.name = "pwm-sifive",
+		.of_match_table = pwm_sifive_of_match,
+	},
+};
+module_platform_driver(pwm_sifive_driver);
+
+MODULE_DESCRIPTION("SiFive PWM driver");
+MODULE_LICENSE("GPL v2");