[PATCH v2 0/2] Update designware pwm driver

[PATCH v2 0/2] Update designware pwm driver

[dongxuyang]

From: Xuyang Dong <dongxuyang@eswincomputing.com>

There is already a patch [1] for the DesignWare PWM driver, 
which is posted by Ben and still under review. 
Based on this patch, this series is a continuation of [1] 
to add support for IP versions 2.11a and later, which 
includes support for "Pulse Width Modulation with 0% 
and 100% Duty Cycle".

Supported chips:
ESWIN EIC7700 series SoC.

Test:
Tested this patch on the Sifive HiFive Premier P550 (which uses the EIC7700
SoC).

[1] https://lore.kernel.org/lkml/20230907161242.67190-1-ben.dooks@codethink.co.uk/

Updates:
  Change in v2:
  - YAML:
    - Remove eswin,eic7700-pwm.yaml. Use snps,dw-apb-timers-pwm2.yaml.
      The description in snps,dw-apb-timers-pwm2.yaml is better.
    - Add the resets property as optional, as defined in the databook.
    - Remove snps,pwm-full-range-enable as no additional property is needed.
  - Driver:
    - Change the file from pwm-dwc-eic7700.c to pwm-dwc-of.c from [1].
    - Define DWC_TIM_VERSION_ID_2_11A 2.11a as the baseline version.
    - Enable the 0% and 100% duty cycle mode by setting dwc->feature if
      the version read from the TIMERS_COMP_VERSION register is later
      than or equal to DWC_TIM_VERSION_ID_2_11A.
    - Use the DIV_ROUND_UP_ULL() to calculate width in the .apply and
      .get_state.
    - Additionally, Power Management (PM) support has been added to the
      pwm-dwc-of.c driver.
    - Drop the headers that are not used.
    - Use devm_clk_get_enabled() instead of devm_clk_get().
    - Drop of_match_ptr.
    - Fix build error with 1ULL << 32.
      Reported-by: kernel test robot <lkp@intel.com>
      Closes: https://lore.kernel.org/oe-kbuild-all/202512061720.j31AsgM7-lkp@intel.com/

  - Link to v1: https://lore.kernel.org/all/20251205090411.1388-1-dongxuyang@eswincomputing.com/
  - Link to v9: https://lore.kernel.org/lkml/20230907161242.67190-1-ben.dooks@codethink.co.uk/

Xuyang Dong (2):
  dt-bindings: pwm: dwc: add reset optional
  pwm: dwc: add of/platform support

 .../bindings/pwm/snps,dw-apb-timers-pwm2.yaml |   3 +
 drivers/pwm/Kconfig                           |  10 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-dwc-core.c                    | 101 ++++++--
 drivers/pwm/pwm-dwc-of.c                      | 216 ++++++++++++++++++
 drivers/pwm/pwm-dwc.h                         |  25 +-
 6 files changed, 327 insertions(+), 29 deletions(-)
 create mode 100644 drivers/pwm/pwm-dwc-of.c

--
2.34.1

[PATCH v2 1/2] dt-bindings: pwm: dwc: add reset optional

[dongxuyang]

From: Xuyang Dong <dongxuyang@eswincomputing.com>

Add the optional resets property.

Signed-off-by: Xuyang Dong <dongxuyang@eswincomputing.com>
---
 .../devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml       | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml b/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
index 7523a89a1773..fd9f73c75121 100644
--- a/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
+++ b/Documentation/devicetree/bindings/pwm/snps,dw-apb-timers-pwm2.yaml
@@ -43,6 +43,9 @@ properties:
       - const: bus
       - const: timer
 
+  resets:
+    maxItems: 1
+
   snps,pwm-number:
     $ref: /schemas/types.yaml#/definitions/uint32
     description: The number of PWM channels configured for this instance
-- 
2.34.1

[PATCH v2 2/2] pwm: dwc: add of/platform support

[dongxuyang]

From: Xuyang Dong <dongxuyang@eswincomputing.com>

The dwc pwm controller can be used in non-PCI systems, so allow
either platform or OF based probing.

Co-developed-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Xiang Xu <xuxiang@eswincomputing.com>
Signed-off-by: Guosheng Wang <wangguosheng@eswincomputing.com>
Signed-off-by: Xuyang Dong <dongxuyang@eswincomputing.com>
---
 drivers/pwm/Kconfig        |  10 ++
 drivers/pwm/Makefile       |   1 +
 drivers/pwm/pwm-dwc-core.c | 101 +++++++++++++----
 drivers/pwm/pwm-dwc-of.c   | 216 +++++++++++++++++++++++++++++++++++++
 drivers/pwm/pwm-dwc.h      |  25 +++--
 5 files changed, 324 insertions(+), 29 deletions(-)
 create mode 100644 drivers/pwm/pwm-dwc-of.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 6f3147518376..50aea24b6168 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -249,6 +249,16 @@ config PWM_DWC
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-dwc.
 
+config PWM_DWC_OF
+	tristate "DesignWare PWM Controller (OF bus)"
+	depends on HAS_IOMEM && (OF || COMPILE_TEST)
+	select PWM_DWC_CORE
+	help
+	  PWM driver for Synopsys DWC PWM Controller on an OF bus or
+	  a platform bus.
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-dwc-of.
+
 config PWM_EP93XX
 	tristate "Cirrus Logic EP93xx PWM support"
 	depends on ARCH_EP93XX || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 0dc0d2b69025..470411a7e5ea 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_PWM_CRC)		+= pwm-crc.o
 obj-$(CONFIG_PWM_CROS_EC)	+= pwm-cros-ec.o
 obj-$(CONFIG_PWM_DWC_CORE)	+= pwm-dwc-core.o
 obj-$(CONFIG_PWM_DWC)		+= pwm-dwc.o
+obj-$(CONFIG_PWM_DWC_OF)	+= pwm-dwc-of.o
 obj-$(CONFIG_PWM_EP93XX)	+= pwm-ep93xx.o
 obj-$(CONFIG_PWM_FSL_FTM)	+= pwm-fsl-ftm.o
 obj-$(CONFIG_PWM_GPIO)		+= pwm-gpio.o
diff --git a/drivers/pwm/pwm-dwc-core.c b/drivers/pwm/pwm-dwc-core.c
index 6dabec93a3c6..93b77dcde8d0 100644
--- a/drivers/pwm/pwm-dwc-core.c
+++ b/drivers/pwm/pwm-dwc-core.c
@@ -12,6 +12,7 @@
 #define DEFAULT_SYMBOL_NAMESPACE "dwc_pwm"
 
 #include <linux/bitops.h>
+#include <linux/clk.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -44,21 +45,52 @@ static int __dwc_pwm_configure_timer(struct dwc_pwm *dwc,
 	u32 high;
 	u32 low;
 
-	/*
-	 * Calculate width of low and high period in terms of input clock
-	 * periods and check are the result within HW limits between 1 and
-	 * 2^32 periods.
-	 */
-	tmp = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, dwc->clk_ns);
-	if (tmp < 1 || tmp > (1ULL << 32))
-		return -ERANGE;
-	low = tmp - 1;
-
-	tmp = DIV_ROUND_CLOSEST_ULL(state->period - state->duty_cycle,
-				    dwc->clk_ns);
-	if (tmp < 1 || tmp > (1ULL << 32))
-		return -ERANGE;
-	high = tmp - 1;
+	if (dwc->clk)
+		dwc->clk_rate = clk_get_rate(dwc->clk);
+
+	if (dwc->features & DWC_TIM_CTRL_0N100PWM_EN) {
+		/*
+		 * Calculate width of low and high period in terms of input
+		 * clock periods and check are the result within HW limits
+		 * between 0 and 2^32 periods.
+		 */
+		tmp = state->duty_cycle * dwc->clk_rate;
+		tmp = DIV_ROUND_UP_ULL(tmp, NSEC_PER_SEC);
+		if (tmp > (1ULL << 32))
+			return -ERANGE;
+
+		if (pwm->args.polarity == PWM_POLARITY_INVERSED)
+			high = tmp;
+		else
+			low = tmp;
+
+		tmp = (state->period - state->duty_cycle) * dwc->clk_rate;
+		tmp = DIV_ROUND_UP_ULL(tmp, NSEC_PER_SEC);
+		if (tmp > (1ULL << 32))
+			return -ERANGE;
+
+		if (pwm->args.polarity == PWM_POLARITY_INVERSED)
+			low = tmp;
+		else
+			high = tmp;
+	} else {
+		/*
+		 * Calculate width of low and high period in terms of input
+		 * clock periods and check are the result within HW limits
+		 * between 1 and 2^32 periods.
+		 */
+		tmp = state->duty_cycle * dwc->clk_rate;
+		tmp = DIV_ROUND_UP_ULL(tmp, NSEC_PER_SEC);
+		if (tmp < 1 || tmp > (1ULL << 32))
+			return -ERANGE;
+		low = tmp - 1;
+
+		tmp = (state->period - state->duty_cycle) * dwc->clk_rate;
+		tmp = DIV_ROUND_UP_ULL(tmp, NSEC_PER_SEC);
+		if (tmp < 1 || tmp > (1ULL << 32))
+			return -ERANGE;
+		high = tmp - 1;
+	}
 
 	/*
 	 * Specification says timer usage flow is to disable timer, then
@@ -74,6 +106,7 @@ static int __dwc_pwm_configure_timer(struct dwc_pwm *dwc,
 	 * width of low period and latter the width of high period in terms
 	 * multiple of input clock periods:
 	 * Width = ((Count + 1) * input clock period).
+	 * Width = (Count * input clock period) : supported 0% and 100%).
 	 */
 	dwc_pwm_writel(dwc, low, DWC_TIM_LD_CNT(pwm->hwpwm));
 	dwc_pwm_writel(dwc, high, DWC_TIM_LD_CNT2(pwm->hwpwm));
@@ -85,6 +118,9 @@ static int __dwc_pwm_configure_timer(struct dwc_pwm *dwc,
 	 * periods are set by Load Count registers.
 	 */
 	ctrl = DWC_TIM_CTRL_MODE_USER | DWC_TIM_CTRL_PWM;
+	if (dwc->features & DWC_TIM_CTRL_0N100PWM_EN)
+		ctrl |= DWC_TIM_CTRL_0N100PWM_EN;
+
 	dwc_pwm_writel(dwc, ctrl, DWC_TIM_CTRL(pwm->hwpwm));
 
 	/*
@@ -121,11 +157,17 @@ static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 			     struct pwm_state *state)
 {
 	struct dwc_pwm *dwc = to_dwc_pwm(chip);
+	unsigned long clk_rate;
 	u64 duty, period;
 	u32 ctrl, ld, ld2;
 
 	pm_runtime_get_sync(pwmchip_parent(chip));
 
+	if (dwc->clk)
+		dwc->clk_rate = clk_get_rate(dwc->clk);
+
+	clk_rate = dwc->clk_rate;
+
 	ctrl = dwc_pwm_readl(dwc, DWC_TIM_CTRL(pwm->hwpwm));
 	ld = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(pwm->hwpwm));
 	ld2 = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(pwm->hwpwm));
@@ -137,17 +179,32 @@ static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * based on the timer load-count only.
 	 */
 	if (ctrl & DWC_TIM_CTRL_PWM) {
-		duty = (ld + 1) * dwc->clk_ns;
-		period = (ld2 + 1)  * dwc->clk_ns;
-		period += duty;
+		if (dwc->features & DWC_TIM_CTRL_0N100PWM_EN) {
+			if (pwm->args.polarity == PWM_POLARITY_INVERSED)
+				duty = ld2;
+			else
+				duty = ld;
+			period = ld + ld2;
+		} else {
+			duty = ld + 1;
+			period = ld2 + 1;
+			period += duty;
+		}
 	} else {
-		duty = (ld + 1) * dwc->clk_ns;
+		duty = ld + 1;
 		period = duty * 2;
 	}
 
 	state->polarity = PWM_POLARITY_INVERSED;
-	state->period = period;
-	state->duty_cycle = duty;
+	/*
+	 * If the ld register is at its maximum value. The duty value is
+	 * 4,294,967,295 (0xFFFF FFFF). The product (duty * NSEC_PER_SEC)
+	 * is guaranteed to be less than 2^64.
+	 */
+	duty *= NSEC_PER_SEC;
+	period *= NSEC_PER_SEC;
+	state->period = DIV_ROUND_UP_ULL(period, clk_rate);
+	state->duty_cycle = DIV_ROUND_UP_ULL(duty, clk_rate);
 
 	pm_runtime_put_sync(pwmchip_parent(chip));
 
@@ -169,7 +226,7 @@ struct pwm_chip *dwc_pwm_alloc(struct device *dev)
 		return chip;
 	dwc = to_dwc_pwm(chip);
 
-	dwc->clk_ns = 10;
+	dwc->clk_rate = NSEC_PER_SEC / 10;
 	chip->ops = &dwc_pwm_ops;
 
 	return chip;
diff --git a/drivers/pwm/pwm-dwc-of.c b/drivers/pwm/pwm-dwc-of.c
new file mode 100644
index 000000000000..df3b733b2c36
--- /dev/null
+++ b/drivers/pwm/pwm-dwc-of.c
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DesignWare PWM Controller driver OF
+ *
+ * Copyright (C) 2026 SiFive, Inc.
+ */
+
+#define DEFAULT_SYMBOL_NAMESPACE "dwc_pwm_of"
+
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pwm.h>
+#include <linux/reset.h>
+
+#include "pwm-dwc.h"
+
+static int dwc_pwm_plat_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct dwc_pwm_drvdata *data;
+	struct pwm_chip *chip;
+	struct dwc_pwm *dwc;
+	u32 nr_pwm, tim_id;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(struct dwc_pwm_drvdata), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	chip = dwc_pwm_alloc(dev);
+	if (IS_ERR(chip))
+		return dev_err_probe(dev, -ENOMEM, "failed to alloc pwm\n");
+
+	dwc = to_dwc_pwm(chip);
+
+	dwc->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(dwc->base))
+		return PTR_ERR(dwc->base);
+
+	if (!device_property_read_u32(dev, "snps,pwm-number", &nr_pwm)) {
+		if (nr_pwm > DWC_TIMERS_TOTAL)
+			dev_warn
+			(dev, "too many PWMs (%d) specified, capping at %d\n",
+			nr_pwm, chip->npwm);
+		else
+			chip->npwm = nr_pwm;
+	}
+
+	dwc->bus_clk = devm_clk_get_enabled(dev, "bus");
+	if (IS_ERR(dwc->bus_clk))
+		return dev_err_probe(dev, PTR_ERR(dwc->bus_clk),
+				     "failed to get bus clock\n");
+
+	dwc->clk = devm_clk_get_enabled(dev, "timer");
+	if (IS_ERR(dwc->clk))
+		return dev_err_probe(dev, PTR_ERR(dwc->clk),
+				     "failed to get timer clock\n");
+
+	ret = devm_clk_rate_exclusive_get(dev, dwc->clk);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to get exclusive rate\n");
+
+	dwc->clk_rate = clk_get_rate(dwc->clk);
+
+	dwc->rst = devm_reset_control_get_optional_exclusive_deasserted(dev,
+									NULL);
+	if (IS_ERR(dwc->rst))
+		return dev_err_probe(dev, PTR_ERR(dwc->rst),
+				     "failed to get reset control\n");
+
+	/* init PWM feature */
+	dwc->features = 0;
+	/*
+	 * Support for 0% and 100% duty cycle mode was added in version 2.11a
+	 * and later.
+	 */
+	tim_id = dwc_pwm_readl(dwc, DWC_TIMERS_COMP_VERSION);
+	if (tim_id >= DWC_TIM_VERSION_ID_2_11A)
+		dwc->features |= DWC_TIM_CTRL_0N100PWM_EN;
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to add pwmchip\n");
+
+	data->chips[0] = chip;
+	dev_set_drvdata(dev, data);
+
+	pm_runtime_set_autosuspend_delay(dev, 5000);
+	pm_runtime_use_autosuspend(dev);
+	devm_pm_runtime_enable(dev);
+
+	return 0;
+}
+
+static void dwc_pwm_plat_remove(struct platform_device *pdev)
+{
+	struct dwc_pwm_drvdata *data = platform_get_drvdata(pdev);
+	struct pwm_chip *chip = data->chips[0];
+
+	for (int idx = 0; idx < chip->npwm; idx++) {
+		if (chip->pwms[idx].state.enabled)
+			pwm_disable(&chip->pwms[idx]);
+	}
+}
+
+static int dwc_pwm_runtime_suspend(struct device *dev)
+{
+	struct dwc_pwm_drvdata *data = dev_get_drvdata(dev);
+	struct pwm_chip *chip = data->chips[0];
+	struct dwc_pwm *dwc = to_dwc_pwm(chip);
+
+	clk_disable_unprepare(dwc->clk);
+	clk_disable_unprepare(dwc->bus_clk);
+
+	return 0;
+}
+
+static int dwc_pwm_runtime_resume(struct device *dev)
+{
+	struct dwc_pwm_drvdata *data = dev_get_drvdata(dev);
+	struct pwm_chip *chip = data->chips[0];
+	struct dwc_pwm *dwc = to_dwc_pwm(chip);
+	int ret;
+
+	ret = clk_prepare_enable(dwc->bus_clk);
+	if (ret) {
+		dev_err(dev, "failed to enable bus clock: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(dwc->clk);
+	if (ret) {
+		dev_err(dev, "failed to enable timer clock: %d\n", ret);
+		clk_disable_unprepare(dwc->bus_clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int dwc_pwm_suspend(struct device *dev)
+{
+	struct dwc_pwm_drvdata *data = dev_get_drvdata(dev);
+	struct pwm_chip *chip = data->chips[0];
+	struct dwc_pwm *dwc = to_dwc_pwm(chip);
+	int idx, ret;
+
+	for (idx = 0; idx < chip->npwm; idx++) {
+		if (chip->pwms[idx].state.enabled)
+			return -EBUSY;
+
+		dwc->ctx[idx].cnt = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(idx));
+		dwc->ctx[idx].cnt2 = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(idx));
+		dwc->ctx[idx].ctrl = dwc_pwm_readl(dwc, DWC_TIM_CTRL(idx));
+	}
+
+	if (!pm_runtime_status_suspended(dev)) {
+		ret = dwc_pwm_runtime_suspend(dev);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int dwc_pwm_resume(struct device *dev)
+{
+	struct dwc_pwm_drvdata *data = dev_get_drvdata(dev);
+	struct pwm_chip *chip = data->chips[0];
+	struct dwc_pwm *dwc = to_dwc_pwm(chip);
+	int idx, ret;
+
+	if (!pm_runtime_status_suspended(dev)) {
+		ret = dwc_pwm_runtime_resume(dev);
+		if (ret)
+			return ret;
+	}
+
+	for (idx = 0; idx < chip->npwm; idx++) {
+		dwc_pwm_writel(dwc, dwc->ctx[idx].cnt, DWC_TIM_LD_CNT(idx));
+		dwc_pwm_writel(dwc, dwc->ctx[idx].cnt2, DWC_TIM_LD_CNT2(idx));
+		dwc_pwm_writel(dwc, dwc->ctx[idx].ctrl, DWC_TIM_CTRL(idx));
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops dwc_pwm_pm_ops = {
+	RUNTIME_PM_OPS(dwc_pwm_runtime_suspend, dwc_pwm_runtime_resume, NULL)
+	SYSTEM_SLEEP_PM_OPS(dwc_pwm_suspend, dwc_pwm_resume)
+};
+
+static const struct of_device_id dwc_pwm_dt_ids[] = {
+	{ .compatible = "snps,dw-apb-timers-pwm2" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, dwc_pwm_dt_ids);
+
+static struct platform_driver dwc_pwm_plat_driver = {
+	.driver = {
+		.name = "dwc-pwm",
+		.pm = pm_sleep_ptr(&dwc_pwm_pm_ops),
+		.of_match_table = dwc_pwm_dt_ids,
+	},
+	.probe = dwc_pwm_plat_probe,
+	.remove = dwc_pwm_plat_remove,
+};
+
+module_platform_driver(dwc_pwm_plat_driver);
+
+MODULE_ALIAS("platform:dwc-pwm-of");
+MODULE_AUTHOR("Ben Dooks <ben.dooks@codethink.co.uk>");
+MODULE_DESCRIPTION("DesignWare PWM Controller");
+MODULE_LICENSE("GPL");
diff --git a/drivers/pwm/pwm-dwc.h b/drivers/pwm/pwm-dwc.h
index 1562594e7f85..75f7c2d031c4 100644
--- a/drivers/pwm/pwm-dwc.h
+++ b/drivers/pwm/pwm-dwc.h
@@ -26,12 +26,19 @@ MODULE_IMPORT_NS("dwc_pwm");
 #define DWC_TIMERS_TOTAL	8
 
 /* Timer Control Register */
-#define DWC_TIM_CTRL_EN		BIT(0)
-#define DWC_TIM_CTRL_MODE	BIT(1)
-#define DWC_TIM_CTRL_MODE_FREE	(0 << 1)
-#define DWC_TIM_CTRL_MODE_USER	(1 << 1)
-#define DWC_TIM_CTRL_INT_MASK	BIT(2)
-#define DWC_TIM_CTRL_PWM	BIT(3)
+#define DWC_TIM_CTRL_EN			BIT(0)
+#define DWC_TIM_CTRL_MODE		BIT(1)
+#define DWC_TIM_CTRL_MODE_FREE		(0 << 1)
+#define DWC_TIM_CTRL_MODE_USER		BIT(1)
+#define DWC_TIM_CTRL_INT_MASK		BIT(2)
+#define DWC_TIM_CTRL_PWM		BIT(3)
+#define DWC_TIM_CTRL_0N100PWM_EN	BIT(4)
+
+/*
+ * The version 2.11a and later add "Pulse Width Modulation with
+ * 0% and 100% Duty Cycle".
+ */
+#define DWC_TIM_VERSION_ID_2_11A	0x3231312a
 
 struct dwc_pwm_info {
 	unsigned int nr;
@@ -52,8 +59,12 @@ struct dwc_pwm_ctx {
 
 struct dwc_pwm {
 	void __iomem *base;
-	unsigned int clk_ns;
+	struct clk *bus_clk;
+	struct clk *clk;
+	unsigned long clk_rate;
+	struct reset_control *rst;
 	struct dwc_pwm_ctx ctx[DWC_TIMERS_TOTAL];
+	u32 features;
 };
 
 static inline struct dwc_pwm *to_dwc_pwm(struct pwm_chip *chip)
-- 
2.34.1

Re: [PATCH v2 1/2] dt-bindings: pwm: dwc: add reset optional

[Krzysztof Kozlowski]

On Fri, Mar 06, 2026 at 05:30:58PM +0800, dongxuyang@eswincomputing.com wrote:
> From: Xuyang Dong <dongxuyang@eswincomputing.com>
> 
> Add the optional resets property.

Why?

> 
> Signed-off-by: Xuyang Dong <dongxuyang@eswincomputing.com>

Best regards,
Krzysztof

Re: [PATCH v2 0/2] Update designware pwm driver

[Krzysztof Kozlowski]

On Fri, Mar 06, 2026 at 05:30:00PM +0800, dongxuyang@eswincomputing.com wrote:
> From: Xuyang Dong <dongxuyang@eswincomputing.com>
> 
> There is already a patch [1] for the DesignWare PWM driver, 

So provide review there instead of allowing Ben to post incomplete
hardware description which you want to correct here...

I don't understand why posting this change.



> which is posted by Ben and still under review. 
> Based on this patch, this series is a continuation of [1] 
> to add support for IP versions 2.11a and later, which 
> includes support for "Pulse Width Modulation with 0% 
> and 100% Duty Cycle".

Best regards,
Krzysztof

Re: [PATCH v2 0/2] Update designware pwm driver

[Krzysztof Kozlowski]

On 07/03/2026 14:24, Krzysztof Kozlowski wrote:
> On Fri, Mar 06, 2026 at 05:30:00PM +0800, dongxuyang@eswincomputing.com wrote:
>> From: Xuyang Dong <dongxuyang@eswincomputing.com>
>>
>> There is already a patch [1] for the DesignWare PWM driver, 
> 
> So provide review there instead of allowing Ben to post incomplete
> hardware description which you want to correct here...
> 
> I don't understand why posting this change.

I see now Ben did not post the bindings change, so this message here
just confused me.

> 
> 
> 
>> which is posted by Ben and still under review. 
>> Based on this patch, this series is a continuation of [1] 
>> to add support for IP versions 2.11a and later, which 
>> includes support for "Pulse Width Modulation with 0% 
>> and 100% Duty Cycle".

But does this mean the patchset cannot be even tested?

> 
> Best regards,
> Krzysztof
> 


Best regards,
Krzysztof

Re: Re: [PATCH v2 1/2] dt-bindings: pwm: dwc: add reset optional

[Xuyang Dong]

> > 
> > Add the optional resets property.
> 
> Why?
> 

Hi Krzysztof,

The DesignWare PWM controller provides separate reset signals dedicated 
to each clock domain, as specified in the hardware documentation. 
Without asserting and deasserting these resets during probe, the PWM 
output may remain in an undefined state after system reboot.

Add optional reset control handling to ensure the controller is
properly initialized.

We will update the commit message in the next version.

Best regards,
Xuyang Dong

> > 
> > Signed-off-by: Xuyang Dong <dongxuyang@eswincomputing.com>
> 
> Best regards,
> Krzysztof

Re: Re: [PATCH v2 0/2] Update designware pwm driver

[Xuyang Dong]

Hi Krzysztof,

> >>
> >> There is already a patch [1] for the DesignWare PWM driver, 
> > 
> > So provide review there instead of allowing Ben to post incomplete
> > hardware description which you want to correct here...
> > 
> > I don't understand why posting this change.
> 
> I see now Ben did not post the bindings change, so this message here
> just confused me.

We noticed Ben’s DesignWare PWM driver series on lore [1]. The patches for 
the DT bindings, pwm-dwc.c and pwm-dwc-core.c have already been merged into 
the kernel, for example, patches 1/6, 2/6, and 3/6. 
However, the pwm-dwc-of.c patch has not yet been accepted, for example, 
patches 4/6, 5/6, and 6/6.
We discussed the status of this PWM series with Ben on lore. Given the lack 
of recent updates following Ben’s message in [2], we’d like to step in and 
help move this forward.

This series is based on v9 and includes the following updates:
1. Migrated to the latest PWM subsystem structure and APIs.
2. Added support for 0% and 100% duty cycle modes.
3. Implemented basic power management (runtime PM) support.

The previous series (v1) has been deprecated. Would it be more 
appropriate to send this as v2 rather than v10?

[1] https://lore.kernel.org/lkml/20230907161242.67190-1-ben.dooks@codethink.co.uk/
[2] https://lore.kernel.org/lkml/0bdd6ab6-bfdd-400e-99b6-cfb186dfcc3e@codethink.co.uk/

The binding file 'snps,dw-apb-timers-pwm2.yaml' has already been merged, 
but the current driver lacks reset support.  
Therefore, patch 1 adds an optional reset property to address this.

We will update the commit message in the next version.

> > 
> > 
> > 
> >> which is posted by Ben and still under review. 
> >> Based on this patch, this series is a continuation of [1] 
> >> to add support for IP versions 2.11a and later, which 
> >> includes support for "Pulse Width Modulation with 0% 
> >> and 100% Duty Cycle".
> 
> But does this mean the patchset cannot be even tested?

Support for 0% and 100% duty cycle mode (available in DesignWare PWM IP
version 2.11a and later) has been tested on the EIC7700 SoC, which
integrates IP version 2.13a.

For Ben's implementation, which does not support this mode, testing can
still be done by setting dwc->features to 0 after reading the version
register, effectively disabling 0% and 100% duty cycle support.

Regards,
Xuyang Dong

Re: [PATCH v2 1/2] dt-bindings: pwm: dwc: add reset optional

[Uwe Kleine-König]

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Hello,

On Mon, Mar 09, 2026 at 05:23:45PM +0800, Xuyang Dong wrote:
> The DesignWare PWM controller provides separate reset signals dedicated 
> to each clock domain, as specified in the hardware documentation. 
> Without asserting and deasserting these resets during probe, the PWM 
> output may remain in an undefined state after system reboot.

Note there is an additional difficulty: A usual wish for machines with a
display is that the bootloader sets up a splash screen that is smoothly
taken over by Linux during boot. A reset of the PWM driving the
backlight then most probably results in a short dark display which
doesn't qualify for smooth.

So if you have a way to distinguish between "random state after
power-on" and "already programmed by the bootloader" this would be
great.

Best regards
Uwe

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Re: [PATCH v2 0/2] Update designware pwm driver

[Ben Dooks]

On 07/03/2026 13:24, Krzysztof Kozlowski wrote:
> On Fri, Mar 06, 2026 at 05:30:00PM +0800, dongxuyang@eswincomputing.com wrote:
>> From: Xuyang Dong <dongxuyang@eswincomputing.com>
>>
>> There is already a patch [1] for the DesignWare PWM driver,
> 
> So provide review there instead of allowing Ben to post incomplete
> hardware description which you want to correct here...
> 
> I don't understand why posting this change.

I think the binding got merged a while ago whilst we ended up never
getting the go-ahead to finish the driver changes. Unfortunately
all the client hardware was returned and we had to destroy all the
data from them.

-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

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