Merge 530c28df03 ("Merge tag 'pwm/for-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm") into android-mainline

Steps on the way to 6.0-rc1

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I42b5b68e2e53ea06316c320d54fb9e3a869d2712

Documentation/devicetree/bindings/pwm/clk-pwm.yaml

@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/clk-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Clock based PWM controller
+
+maintainers:
+  - Nikita Travkin <nikita@trvn.ru>
+
+description: |
+  Some systems have clocks that can be exposed to external devices.
+  (e.g. by muxing them to GPIO pins)
+  It's often possible to control duty-cycle of such clocks which makes them
+  suitable for generating PWM signal.
+
+allOf:
+  - $ref: pwm.yaml#
+
+properties:
+  compatible:
+    const: clk-pwm
+
+  clocks:
+    description: Clock used to generate the signal.
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 2
+
+unevaluatedProperties: false
+
+required:
+  - compatible
+  - clocks
+
+examples:
+  - |
+    pwm {
+      compatible = "clk-pwm";
+      #pwm-cells = <2>;
+      clocks = <&gcc 0>;
+      pinctrl-names = "default";
+      pinctrl-0 = <&pwm_clk_flash_default>;
+    };

Documentation/devicetree/bindings/pwm/pwm-mediatek.txt

@@ -9,6 +9,8 @@ Required properties:
    - "mediatek,mt7628-pwm": found on mt7628 SoC.
    - "mediatek,mt7629-pwm": found on mt7629 SoC.
    - "mediatek,mt8183-pwm": found on mt8183 SoC.
+   - "mediatek,mt8195-pwm", "mediatek,mt8183-pwm": found on mt8195 SoC.
+   - "mediatek,mt8365-pwm": found on mt8365 SoC.
    - "mediatek,mt8516-pwm": found on mt8516 SoC.
  - reg: physical base address and length of the controller's registers.
  - #pwm-cells: must be 2. See pwm.yaml in this directory for a description of
@@ -18,6 +20,7 @@ Required properties:
                 has no clocks
    - "top": the top clock generator
    - "main": clock used by the PWM core
+   - "pwm1-3": the three per PWM clocks for mt8365
    - "pwm1-8": the eight per PWM clocks for mt2712
    - "pwm1-6": the six per PWM clocks for mt7622
    - "pwm1-5": the five per PWM clocks for mt7623

MAINTAINERS

@@ -16384,7 +16384,6 @@ F:	drivers/media/rc/pwm-ir-tx.c
 PWM SUBSYSTEM
 M:	Thierry Reding <thierry.reding@gmail.com>
 R:	Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
-M:	Lee Jones <lee.jones@linaro.org>
 L:	linux-pwm@vger.kernel.org
 S:	Maintained
 Q:	https://patchwork.ozlabs.org/project/linux-pwm/list/
@@ -16395,6 +16394,7 @@ F:	Documentation/driver-api/pwm.rst
 F:	drivers/gpio/gpio-mvebu.c
 F:	drivers/pwm/
 F:	drivers/video/backlight/pwm_bl.c
+F:	include/dt-bindings/pwm/
 F:	include/linux/pwm.h
 F:	include/linux/pwm_backlight.h
 K:	pwm_(config|apply_state|ops)

drivers/pwm/Kconfig

@@ -140,6 +140,16 @@ config PWM_BRCMSTB
 	  To compile this driver as a module, choose M Here: the module
 	  will be called pwm-brcmstb.c.
 
+config PWM_CLK
+	tristate "Clock based PWM support"
+	depends on HAVE_CLK || COMPILE_TEST
+	help
+	  Generic PWM framework driver for outputs that can be
+	  muxed to clocks.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-clk.
+
 config PWM_CLPS711X
 	tristate "CLPS711X PWM support"
 	depends on ARCH_CLPS711X || COMPILE_TEST

drivers/pwm/Makefile

@@ -10,6 +10,7 @@ obj-$(CONFIG_PWM_BCM_KONA)	+= pwm-bcm-kona.o
 obj-$(CONFIG_PWM_BCM2835)	+= pwm-bcm2835.o
 obj-$(CONFIG_PWM_BERLIN)	+= pwm-berlin.o
 obj-$(CONFIG_PWM_BRCMSTB)	+= pwm-brcmstb.o
+obj-$(CONFIG_PWM_CLK)		+= pwm-clk.o
 obj-$(CONFIG_PWM_CLPS711X)	+= pwm-clps711x.o
 obj-$(CONFIG_PWM_CRC)		+= pwm-crc.o
 obj-$(CONFIG_PWM_CROS_EC)	+= pwm-cros-ec.o

drivers/pwm/core.c

@@ -235,18 +235,8 @@ EXPORT_SYMBOL_GPL(pwm_get_chip_data);
 
 static bool pwm_ops_check(const struct pwm_chip *chip)
 {
-
 	const struct pwm_ops *ops = chip->ops;
 
-	/* driver supports legacy, non-atomic operation */
-	if (ops->config && ops->enable && ops->disable) {
-		if (IS_ENABLED(CONFIG_PWM_DEBUG))
-			dev_warn(chip->dev,
-				 "Driver needs updating to atomic API\n");
-
-		return true;
-	}
-
 	if (!ops->apply)
 		return false;
 
@@ -548,73 +538,6 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 	}
 }
 
-static int pwm_apply_legacy(struct pwm_chip *chip, struct pwm_device *pwm,
-			    const struct pwm_state *state)
-{
-	int err;
-	struct pwm_state initial_state = pwm->state;
-
-	if (state->polarity != pwm->state.polarity) {
-		if (!chip->ops->set_polarity)
-			return -EINVAL;
-
-		/*
-		 * Changing the polarity of a running PWM is only allowed when
-		 * the PWM driver implements ->apply().
-		 */
-		if (pwm->state.enabled) {
-			chip->ops->disable(chip, pwm);
-
-			/*
-			 * Update pwm->state already here in case
-			 * .set_polarity() or another callback depend on that.
-			 */
-			pwm->state.enabled = false;
-		}
-
-		err = chip->ops->set_polarity(chip, pwm, state->polarity);
-		if (err)
-			goto rollback;
-
-		pwm->state.polarity = state->polarity;
-	}
-
-	if (!state->enabled) {
-		if (pwm->state.enabled)
-			chip->ops->disable(chip, pwm);
-
-		return 0;
-	}
-
-	/*
-	 * We cannot skip calling ->config even if state->period ==
-	 * pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
-	 * because we might have exited early in the last call to
-	 * pwm_apply_state because of !state->enabled and so the two values in
-	 * pwm->state might not be configured in hardware.
-	 */
-	err = chip->ops->config(pwm->chip, pwm,
-				state->duty_cycle,
-				state->period);
-	if (err)
-		goto rollback;
-
-	pwm->state.period = state->period;
-	pwm->state.duty_cycle = state->duty_cycle;
-
-	if (!pwm->state.enabled) {
-		err = chip->ops->enable(chip, pwm);
-		if (err)
-			goto rollback;
-	}
-
-	return 0;
-
-rollback:
-	pwm->state = initial_state;
-	return err;
-}
-
 /**
  * pwm_apply_state() - atomically apply a new state to a PWM device
  * @pwm: PWM device
@@ -647,10 +570,7 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
 	    state->usage_power == pwm->state.usage_power)
 		return 0;
 
-	if (chip->ops->apply)
-		err = chip->ops->apply(chip, pwm, state);
-	else
-		err = pwm_apply_legacy(chip, pwm, state);
+	err = chip->ops->apply(chip, pwm, state);
 	if (err)
 		return err;
 

drivers/pwm/pwm-atmel-tcb.c

@@ -304,7 +304,7 @@ static int atmel_tcb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	/*
 	 * Find best clk divisor:
 	 * the smallest divisor which can fulfill the period_ns requirements.
-	 * If there is a gclk, the first divisor is actuallly the gclk selector
+	 * If there is a gclk, the first divisor is actually the gclk selector
 	 */
 	if (tcbpwmc->gclk)
 		i = 1;

drivers/pwm/pwm-clk.c

@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Clock based PWM controller
+ *
+ * Copyright (c) 2021 Nikita Travkin <nikita@trvn.ru>
+ *
+ * This is an "adapter" driver that allows PWM consumers to use
+ * system clocks with duty cycle control as PWM outputs.
+ *
+ * Limitations:
+ * - Due to the fact that exact behavior depends on the underlying
+ *   clock driver, various limitations are possible.
+ * - Underlying clock may not be able to give 0% or 100% duty cycle
+ *   (constant off or on), exact behavior will depend on the clock.
+ * - When the PWM is disabled, the clock will be disabled as well,
+ *   line state will depend on the clock.
+ * - The clk API doesn't expose the necessary calls to implement
+ *   .get_state().
+ */
+
+#include <linux/kernel.h>
+#include <linux/math64.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/pwm.h>
+
+struct pwm_clk_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	bool clk_enabled;
+};
+
+#define to_pwm_clk_chip(_chip) container_of(_chip, struct pwm_clk_chip, chip)
+
+static int pwm_clk_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			 const struct pwm_state *state)
+{
+	struct pwm_clk_chip *pcchip = to_pwm_clk_chip(chip);
+	int ret;
+	u32 rate;
+	u64 period = state->period;
+	u64 duty_cycle = state->duty_cycle;
+
+	if (!state->enabled) {
+		if (pwm->state.enabled) {
+			clk_disable(pcchip->clk);
+			pcchip->clk_enabled = false;
+		}
+		return 0;
+	} else if (!pwm->state.enabled) {
+		ret = clk_enable(pcchip->clk);
+		if (ret)
+			return ret;
+		pcchip->clk_enabled = true;
+	}
+
+	/*
+	 * We have to enable the clk before setting the rate and duty_cycle,
+	 * that however results in a window where the clk is on with a
+	 * (potentially) different setting. Also setting period and duty_cycle
+	 * are two separate calls, so that probably isn't atomic either.
+	 */
+
+	rate = DIV64_U64_ROUND_UP(NSEC_PER_SEC, period);
+	ret = clk_set_rate(pcchip->clk, rate);
+	if (ret)
+		return ret;
+
+	if (state->polarity == PWM_POLARITY_INVERSED)
+		duty_cycle = period - duty_cycle;
+
+	return clk_set_duty_cycle(pcchip->clk, duty_cycle, period);
+}
+
+static const struct pwm_ops pwm_clk_ops = {
+	.apply = pwm_clk_apply,
+	.owner = THIS_MODULE,
+};
+
+static int pwm_clk_probe(struct platform_device *pdev)
+{
+	struct pwm_clk_chip *pcchip;
+	int ret;
+
+	pcchip = devm_kzalloc(&pdev->dev, sizeof(*pcchip), GFP_KERNEL);
+	if (!pcchip)
+		return -ENOMEM;
+
+	pcchip->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(pcchip->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(pcchip->clk),
+				     "Failed to get clock\n");
+
+	pcchip->chip.dev = &pdev->dev;
+	pcchip->chip.ops = &pwm_clk_ops;
+	pcchip->chip.npwm = 1;
+
+	ret = clk_prepare(pcchip->clk);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "Failed to prepare clock\n");
+
+	ret = pwmchip_add(&pcchip->chip);
+	if (ret < 0) {
+		clk_unprepare(pcchip->clk);
+		return dev_err_probe(&pdev->dev, ret, "Failed to add pwm chip\n");
+	}
+
+	platform_set_drvdata(pdev, pcchip);
+	return 0;
+}
+
+static int pwm_clk_remove(struct platform_device *pdev)
+{
+	struct pwm_clk_chip *pcchip = platform_get_drvdata(pdev);
+
+	pwmchip_remove(&pcchip->chip);
+
+	if (pcchip->clk_enabled)
+		clk_disable(pcchip->clk);
+
+	clk_unprepare(pcchip->clk);
+
+	return 0;
+}
+
+static const struct of_device_id pwm_clk_dt_ids[] = {
+	{ .compatible = "clk-pwm", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pwm_clk_dt_ids);
+
+static struct platform_driver pwm_clk_driver = {
+	.driver = {
+		.name = "pwm-clk",
+		.of_match_table = pwm_clk_dt_ids,
+	},
+	.probe = pwm_clk_probe,
+	.remove = pwm_clk_remove,
+};
+module_platform_driver(pwm_clk_driver);
+
+MODULE_ALIAS("platform:pwm-clk");
+MODULE_AUTHOR("Nikita Travkin <nikita@trvn.ru>");
+MODULE_DESCRIPTION("Clock based PWM driver");
+MODULE_LICENSE("GPL");

drivers/pwm/pwm-lpc18xx-sct.c

@@ -98,7 +98,7 @@ struct lpc18xx_pwm_chip {
 	unsigned long clk_rate;
 	unsigned int period_ns;
 	unsigned int min_period_ns;
-	unsigned int max_period_ns;
+	u64 max_period_ns;
 	unsigned int period_event;
 	unsigned long event_map;
 	struct mutex res_lock;
@@ -145,40 +145,48 @@ static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 	mutex_unlock(&lpc18xx_pwm->res_lock);
 }
 
-static void lpc18xx_pwm_config_period(struct pwm_chip *chip, int period_ns)
+static void lpc18xx_pwm_config_period(struct pwm_chip *chip, u64 period_ns)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
-	u64 val;
+	u32 val;
 
-	val = (u64)period_ns * lpc18xx_pwm->clk_rate;
-	do_div(val, NSEC_PER_SEC);
+	/*
+	 * With clk_rate < NSEC_PER_SEC this cannot overflow.
+	 * With period_ns < max_period_ns this also fits into an u32.
+	 * As period_ns >= min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC, lpc18xx_pwm->clk_rate);
+	 * we have val >= 1.
+	 */
+	val = mul_u64_u64_div_u64(period_ns, lpc18xx_pwm->clk_rate, NSEC_PER_SEC);
 
 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
-			   (u32)val - 1);
+			   val - 1);
 
 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
-			   (u32)val - 1);
+			   val - 1);
 }
 
 static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
-				    struct pwm_device *pwm, int duty_ns)
+				    struct pwm_device *pwm, u64 duty_ns)
 {
 	struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 	struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
-	u64 val;
+	u32 val;
 
-	val = (u64)duty_ns * lpc18xx_pwm->clk_rate;
-	do_div(val, NSEC_PER_SEC);
+	/*
+	 * With clk_rate < NSEC_PER_SEC this cannot overflow.
+	 * With duty_ns <= period_ns < max_period_ns this also fits into an u32.
+	 */
+	val = mul_u64_u64_div_u64(duty_ns, lpc18xx_pwm->clk_rate, NSEC_PER_SEC);
 
 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
-			   (u32)val);
+			   val);
 
 	lpc18xx_pwm_writel(lpc18xx_pwm,
 			   LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
-			   (u32)val);
+			   val);
 }
 
 static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
@@ -359,30 +367,35 @@ static int lpc18xx_pwm_probe(struct platform_device *pdev)
 		return PTR_ERR(lpc18xx_pwm->base);
 
 	lpc18xx_pwm->pwm_clk = devm_clk_get(&pdev->dev, "pwm");
-	if (IS_ERR(lpc18xx_pwm->pwm_clk)) {
-		dev_err(&pdev->dev, "failed to get pwm clock\n");
-		return PTR_ERR(lpc18xx_pwm->pwm_clk);
-	}
+	if (IS_ERR(lpc18xx_pwm->pwm_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(lpc18xx_pwm->pwm_clk),
+				     "failed to get pwm clock\n");
 
 	ret = clk_prepare_enable(lpc18xx_pwm->pwm_clk);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "could not prepare or enable pwm clock\n");
-		return ret;
-	}
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret,
+				     "could not prepare or enable pwm clock\n");
 
 	lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
 	if (!lpc18xx_pwm->clk_rate) {
-		dev_err(&pdev->dev, "pwm clock has no frequency\n");
-		ret = -EINVAL;
+		ret = dev_err_probe(&pdev->dev,
+				    -EINVAL, "pwm clock has no frequency\n");
+		goto disable_pwmclk;
+	}
+
+	/*
+	 * If clkrate is too fast, the calculations in .apply() might overflow.
+	 */
+	if (lpc18xx_pwm->clk_rate > NSEC_PER_SEC) {
+		ret = dev_err_probe(&pdev->dev, -EINVAL, "pwm clock to fast\n");
 		goto disable_pwmclk;
 	}
 
 	mutex_init(&lpc18xx_pwm->res_lock);
 	mutex_init(&lpc18xx_pwm->period_lock);
 
-	val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX;
-	do_div(val, lpc18xx_pwm->clk_rate);
-	lpc18xx_pwm->max_period_ns = val;
+	lpc18xx_pwm->max_period_ns =
+		mul_u64_u64_div_u64(NSEC_PER_SEC, LPC18XX_PWM_TIMER_MAX, lpc18xx_pwm->clk_rate);
 
 	lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
 						  lpc18xx_pwm->clk_rate);
@@ -423,7 +436,7 @@ static int lpc18xx_pwm_probe(struct platform_device *pdev)
 
 	ret = pwmchip_add(&lpc18xx_pwm->chip);
 	if (ret < 0) {
-		dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
+		dev_err_probe(&pdev->dev, ret, "pwmchip_add failed\n");
 		goto disable_pwmclk;
 	}
 

drivers/pwm/pwm-mediatek.c

@@ -323,6 +323,12 @@ static const struct pwm_mediatek_of_data mt8183_pwm_data = {
 	.has_ck_26m_sel = true,
 };
 
+static const struct pwm_mediatek_of_data mt8365_pwm_data = {
+	.num_pwms = 3,
+	.pwm45_fixup = false,
+	.has_ck_26m_sel = true,
+};
+
 static const struct pwm_mediatek_of_data mt8516_pwm_data = {
 	.num_pwms = 5,
 	.pwm45_fixup = false,
@@ -337,6 +343,7 @@ static const struct of_device_id pwm_mediatek_of_match[] = {
 	{ .compatible = "mediatek,mt7628-pwm", .data = &mt7628_pwm_data },
 	{ .compatible = "mediatek,mt7629-pwm", .data = &mt7629_pwm_data },
 	{ .compatible = "mediatek,mt8183-pwm", .data = &mt8183_pwm_data },
+	{ .compatible = "mediatek,mt8365-pwm", .data = &mt8365_pwm_data },
 	{ .compatible = "mediatek,mt8516-pwm", .data = &mt8516_pwm_data },
 	{ },
 };

drivers/pwm/pwm-sifive.c

@@ -23,7 +23,7 @@
 #define PWM_SIFIVE_PWMCFG		0x0
 #define PWM_SIFIVE_PWMCOUNT		0x8
 #define PWM_SIFIVE_PWMS			0x10
-#define PWM_SIFIVE_PWMCMP0		0x20
+#define PWM_SIFIVE_PWMCMP(i)		(0x20 + 4 * (i))
 
 /* PWMCFG fields */
 #define PWM_SIFIVE_PWMCFG_SCALE		GENMASK(3, 0)
@@ -36,14 +36,12 @@
 #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 mutex lock; /* lock to protect user_count and approx_period */
 	struct notifier_block notifier;
 	struct clk *clk;
 	void __iomem *regs;
@@ -78,6 +76,7 @@ static void pwm_sifive_free(struct pwm_chip *chip, struct pwm_device *pwm)
 	mutex_unlock(&ddata->lock);
 }
 
+/* Called holding ddata->lock */
 static void pwm_sifive_update_clock(struct pwm_sifive_ddata *ddata,
 				    unsigned long rate)
 {
@@ -112,8 +111,7 @@ static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	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);
+	duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
 
 	state->enabled = duty > 0;
 
@@ -127,24 +125,6 @@ static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	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;
-		}
-	} else {
-		clk_disable(ddata->clk);
-	}
-
-	return 0;
-}
-
 static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			    const struct pwm_state *state)
 {
@@ -159,13 +139,6 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	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;
 
@@ -184,25 +157,36 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	/* The hardware cannot generate a 100% duty cycle */
 	frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
 
+	mutex_lock(&ddata->lock);
 	if (state->period != ddata->approx_period) {
 		if (ddata->user_count != 1) {
-			ret = -EBUSY;
-			goto exit;
+			mutex_unlock(&ddata->lock);
+			return -EBUSY;
 		}
 		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;
+
+	/*
+	 * If the PWM is enabled the clk is already on. So only enable it
+	 * conditionally to have it on exactly once afterwards independent of
+	 * the PWM state.
+	 */
+	if (!enabled) {
+		ret = clk_enable(ddata->clk);
+		if (ret) {
+			dev_err(ddata->chip.dev, "Enable clk failed\n");
+			return ret;
+		}
+	}
+
+	writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
+
+	if (!state->enabled)
+		clk_disable(ddata->clk);
+
+	return 0;
 }
 
 static const struct pwm_ops pwm_sifive_ops = {
@@ -232,6 +216,8 @@ static int pwm_sifive_probe(struct platform_device *pdev)
 	struct pwm_sifive_ddata *ddata;
 	struct pwm_chip *chip;
 	int ret;
+	u32 val;
+	unsigned int enabled_pwms = 0, enabled_clks = 1;
 
 	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
 	if (!ddata)
@@ -258,6 +244,33 @@ static int pwm_sifive_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	val = readl(ddata->regs + PWM_SIFIVE_PWMCFG);
+	if (val & PWM_SIFIVE_PWMCFG_EN_ALWAYS) {
+		unsigned int i;
+
+		for (i = 0; i < chip->npwm; ++i) {
+			val = readl(ddata->regs + PWM_SIFIVE_PWMCMP(i));
+			if (val > 0)
+				++enabled_pwms;
+		}
+	}
+
+	/* The clk should be on once for each running PWM. */
+	if (enabled_pwms) {
+		while (enabled_clks < enabled_pwms) {
+			/* This is not expected to fail as the clk is already on */
+			ret = clk_enable(ddata->clk);
+			if (unlikely(ret)) {
+				dev_err_probe(dev, ret, "Failed to enable clk\n");
+				goto disable_clk;
+			}
+			++enabled_clks;
+		}
+	} else {
+		clk_disable(ddata->clk);
+		enabled_clks = 0;
+	}
+
 	/* Watch for changes to underlying clock frequency */
 	ddata->notifier.notifier_call = pwm_sifive_clock_notifier;
 	ret = clk_notifier_register(ddata->clk, &ddata->notifier);
@@ -280,7 +293,11 @@ static int pwm_sifive_probe(struct platform_device *pdev)
 unregister_clk:
 	clk_notifier_unregister(ddata->clk, &ddata->notifier);
 disable_clk:
-	clk_disable_unprepare(ddata->clk);
+	while (enabled_clks) {
+		clk_disable(ddata->clk);
+		--enabled_clks;
+	}
+	clk_unprepare(ddata->clk);
 
 	return ret;
 }
@@ -288,24 +305,20 @@ disable_clk:
 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 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);
 	pwmchip_remove(&ddata->chip);
 	clk_notifier_unregister(ddata->clk, &ddata->notifier);
 
+	for (ch = 0; ch < ddata->chip.npwm; ch++) {
+		pwm = &ddata->chip.pwms[ch];
+		if (pwm->state.enabled)
+			clk_disable(ddata->clk);
+	}
+
+	clk_unprepare(ddata->clk);
+
 	return 0;
 }
 

drivers/pwm/pwm-twl-led.c

@@ -7,6 +7,22 @@
  *
  * This driver is a complete rewrite of the former pwm-twl6030.c authorded by:
  * Hemanth V <hemanthv@ti.com>
+ *
+ * Reference manual for the twl6030 is available at:
+ * https://www.ti.com/lit/ds/symlink/twl6030.pdf
+ *
+ * Limitations:
+ * - The twl6030 hardware only supports two period lengths (128 clock ticks and
+ *   64 clock ticks), the driver only uses 128 ticks
+ * - The hardware doesn't support ON = 0, so the active part of a period doesn't
+ *   start at its beginning.
+ * - The hardware could support inverted polarity (with a similar limitation as
+ *   for normal: the last clock tick is always inactive).
+ * - The hardware emits a constant low output when disabled.
+ * - A request for .duty_cycle = 0 results in an output wave with one active
+ *   clock tick per period. This should better use the disabled state.
+ * - The driver only implements setting the relative duty cycle.
+ * - The driver doesn't implement .get_state().
  */
 
 #include <linux/module.h>

include/linux/pwm.h

@@ -6,9 +6,6 @@
 #include <linux/mutex.h>
 #include <linux/of.h>
 
-struct pwm_capture;
-struct seq_file;
-
 struct pwm_chip;
 
 /**
@@ -251,6 +248,16 @@ pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
 	return 0;
 }
 
+/**
+ * struct pwm_capture - PWM capture data
+ * @period: period of the PWM signal (in nanoseconds)
+ * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
+ */
+struct pwm_capture {
+	unsigned int period;
+	unsigned int duty_cycle;
+};
+
 /**
  * struct pwm_ops - PWM controller operations
  * @request: optional hook for requesting a PWM
@@ -261,10 +268,6 @@ pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
  *	       called once per PWM device when the PWM chip is
  *	       registered.
  * @owner: helps prevent removal of modules exporting active PWMs
- * @config: configure duty cycles and period length for this PWM
- * @set_polarity: configure the polarity of this PWM
- * @enable: enable PWM output toggling
- * @disable: disable PWM output toggling
  */
 struct pwm_ops {
 	int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
@@ -276,14 +279,6 @@ struct pwm_ops {
 	void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
 			  struct pwm_state *state);
 	struct module *owner;
-
-	/* Only used by legacy drivers */
-	int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
-		      int duty_ns, int period_ns);
-	int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
-			    enum pwm_polarity polarity);
-	int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
-	void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
 };
 
 /**
@@ -312,16 +307,6 @@ struct pwm_chip {
 	struct pwm_device *pwms;
 };
 
-/**
- * struct pwm_capture - PWM capture data
- * @period: period of the PWM signal (in nanoseconds)
- * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
- */
-struct pwm_capture {
-	unsigned int period;
-	unsigned int duty_cycle;
-};
-
 #if IS_ENABLED(CONFIG_PWM)
 /* PWM user APIs */
 struct pwm_device *pwm_request(int pwm_id, const char *label);