[PATCH v2 0/7] Tegra264 PWM support

[PATCH v2 0/7] Tegra264 PWM support

[Mikko Perttunen]

Hello,

this adds support for the PWM controller on Tegra264. The controller
is similar to previous generations, but the register fields are
widened, the depth is made configurable, and the enable bit moves
to a different spot.

This series adds only basic support with fixed depth -- configurable
depth will come later.

Patch 1 adds device tree bindings for the Tegra194 and Tegra264
compatible strings.

Patches 2 to 6 contain the PWM driver changes.

Patch 7 adds device tree nodes for the PWM controllers on Tegra264.

Thanks,
Mikko

---
Changes in v2:
- Added device tree binding and Tegra264 device tree patches by Thierry.
- Link to v1: https://lore.kernel.org/r/20260323-t264-pwm-v1-0-4c4ff743050f@nvidia.com

---
Mikko Perttunen (4):
      pwm: tegra: Modify read/write accessors for multi-register channel
      pwm: tegra: Parametrize enable register offset
      pwm: tegra: Parametrize duty and scale field widths
      pwm: tegra: Add support for Tegra264

Thierry Reding (2):
      dt-bindings: pwm: Document Tegra194 and Tegra264 controllers
      arm64: tegra: Add PWM controllers on Tegra264

Yi-Wei Wang (1):
      pwm: tegra: Avoid hard-coded max clock frequency

 .../bindings/pwm/nvidia,tegra20-pwm.yaml           |   2 +
 arch/arm64/boot/dts/nvidia/tegra264.dtsi           |  72 +++++++++++
 drivers/pwm/pwm-tegra.c                            | 141 ++++++++++++++-------
 3 files changed, 172 insertions(+), 43 deletions(-)
---
base-commit: 11439c4635edd669ae435eec308f4ab8a0804808
change-id: 20260303-t264-pwm-57e10d039df1

[PATCH v2 1/7] dt-bindings: pwm: Document Tegra194 and Tegra264 controllers

[Mikko Perttunen]

From: Thierry Reding <treding@nvidia.com>

The PWM controller found on Tegra264 is largely compatible with the one
on prior generations, but it comes with some extra features, hence a new
compatible string is needed.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
 Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
index 41cea4979132..15706d2a808d 100644
--- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
+++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
@@ -16,6 +16,8 @@ properties:
       - enum:
           - nvidia,tegra20-pwm
           - nvidia,tegra186-pwm
+          - nvidia,tegra194-pwm
+          - nvidia,tegra264-pwm
 
       - items:
           - enum:

-- 
2.53.0

[PATCH v2 2/7] pwm: tegra: Avoid hard-coded max clock frequency

[Mikko Perttunen]

From: Yi-Wei Wang <yiweiw@nvidia.com>

The clock driving the Tegra PWM IP can be sourced from different parent
clocks. Hence, let dev_pm_opp_set_rate() set the max clock rate based
upon the current parent clock that can be specified via device-tree.

After this, the Tegra194 SoC data becomes redundant, so get rid of it.

Signed-off-by: Yi-Wei Wang <yiweiw@nvidia.com>
Co-developed-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
 drivers/pwm/pwm-tegra.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index 172063b51d44..759b98b97b6e 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/drivers/pwm/pwm-tegra.c
@@ -59,9 +59,6 @@
 
 struct tegra_pwm_soc {
 	unsigned int num_channels;
-
-	/* Maximum IP frequency for given SoCs */
-	unsigned long max_frequency;
 };
 
 struct tegra_pwm_chip {
@@ -303,7 +300,7 @@ static int tegra_pwm_probe(struct platform_device *pdev)
 		return ret;
 
 	/* Set maximum frequency of the IP */
-	ret = dev_pm_opp_set_rate(&pdev->dev, pc->soc->max_frequency);
+	ret = dev_pm_opp_set_rate(&pdev->dev, S64_MAX);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Failed to set max frequency: %d\n", ret);
 		goto put_pm;
@@ -318,7 +315,7 @@ static int tegra_pwm_probe(struct platform_device *pdev)
 
 	/* Set minimum limit of PWM period for the IP */
 	pc->min_period_ns =
-	    (NSEC_PER_SEC / (pc->soc->max_frequency >> PWM_DUTY_WIDTH)) + 1;
+	    (NSEC_PER_SEC / (pc->clk_rate >> PWM_DUTY_WIDTH)) + 1;
 
 	pc->rst = devm_reset_control_get_exclusive(&pdev->dev, "pwm");
 	if (IS_ERR(pc->rst)) {
@@ -397,23 +394,16 @@ static int __maybe_unused tegra_pwm_runtime_resume(struct device *dev)
 
 static const struct tegra_pwm_soc tegra20_pwm_soc = {
 	.num_channels = 4,
-	.max_frequency = 48000000UL,
 };
 
 static const struct tegra_pwm_soc tegra186_pwm_soc = {
 	.num_channels = 1,
-	.max_frequency = 102000000UL,
-};
-
-static const struct tegra_pwm_soc tegra194_pwm_soc = {
-	.num_channels = 1,
-	.max_frequency = 408000000UL,
 };
 
 static const struct of_device_id tegra_pwm_of_match[] = {
 	{ .compatible = "nvidia,tegra20-pwm", .data = &tegra20_pwm_soc },
 	{ .compatible = "nvidia,tegra186-pwm", .data = &tegra186_pwm_soc },
-	{ .compatible = "nvidia,tegra194-pwm", .data = &tegra194_pwm_soc },
+	{ .compatible = "nvidia,tegra194-pwm", .data = &tegra186_pwm_soc },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);

-- 
2.53.0

[PATCH v2 3/7] pwm: tegra: Modify read/write accessors for multi-register channel

[Mikko Perttunen]

On Tegra264, each PWM instance has two registers (per channel, of which
there is one). Update the pwm_readl/pwm_writel helper functions to
take channel (as struct pwm_device *) and offset separately.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
 drivers/pwm/pwm-tegra.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index 759b98b97b6e..cf54f75d92a5 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/drivers/pwm/pwm-tegra.c
@@ -57,6 +57,8 @@
 #define PWM_SCALE_WIDTH	13
 #define PWM_SCALE_SHIFT	0
 
+#define PWM_CSR_0	0
+
 struct tegra_pwm_soc {
 	unsigned int num_channels;
 };
@@ -78,14 +80,18 @@ static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
 	return pwmchip_get_drvdata(chip);
 }
 
-static inline u32 pwm_readl(struct tegra_pwm_chip *pc, unsigned int offset)
+static inline u32 pwm_readl(struct pwm_device *dev, unsigned int offset)
 {
-	return readl(pc->regs + (offset << 4));
+	struct tegra_pwm_chip *chip = to_tegra_pwm_chip(dev->chip);
+
+	return readl(chip->regs + (dev->hwpwm * 16) + offset);
 }
 
-static inline void pwm_writel(struct tegra_pwm_chip *pc, unsigned int offset, u32 value)
+static inline void pwm_writel(struct pwm_device *dev, unsigned int offset, u32 value)
 {
-	writel(value, pc->regs + (offset << 4));
+	struct tegra_pwm_chip *chip = to_tegra_pwm_chip(dev->chip);
+
+	writel(value, chip->regs + (dev->hwpwm * 16) + offset);
 }
 
 static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
@@ -194,7 +200,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	} else
 		val |= PWM_ENABLE;
 
-	pwm_writel(pc, pwm->hwpwm, val);
+	pwm_writel(pwm, PWM_CSR_0, val);
 
 	/*
 	 * If the PWM is not enabled, turn the clock off again to save power.
@@ -207,7 +213,6 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
-	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 	int rc = 0;
 	u32 val;
 
@@ -215,21 +220,20 @@ static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	if (rc)
 		return rc;
 
-	val = pwm_readl(pc, pwm->hwpwm);
+	val = pwm_readl(pwm, PWM_CSR_0);
 	val |= PWM_ENABLE;
-	pwm_writel(pc, pwm->hwpwm, val);
+	pwm_writel(pwm, PWM_CSR_0, val);
 
 	return 0;
 }
 
 static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
-	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 	u32 val;
 
-	val = pwm_readl(pc, pwm->hwpwm);
+	val = pwm_readl(pwm, PWM_CSR_0);
 	val &= ~PWM_ENABLE;
-	pwm_writel(pc, pwm->hwpwm, val);
+	pwm_writel(pwm, PWM_CSR_0, val);
 
 	pm_runtime_put_sync(pwmchip_parent(chip));
 }

-- 
2.53.0

[PATCH v2 4/7] pwm: tegra: Parametrize enable register offset

[Mikko Perttunen]

On Tegra264, the PWM enablement bit is not located at the base address
of the PWM controller. Hence, introduce an enablement offset field in
the tegra_pwm_soc structure to describe the offset of the register.

Co-developed-by: Yi-Wei Wang <yiweiw@nvidia.com>
Signed-off-by: Yi-Wei Wang <yiweiw@nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
 drivers/pwm/pwm-tegra.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index cf54f75d92a5..22d709986e8c 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/drivers/pwm/pwm-tegra.c
@@ -61,6 +61,7 @@
 
 struct tegra_pwm_soc {
 	unsigned int num_channels;
+	unsigned int enable_reg;
 };
 
 struct tegra_pwm_chip {
@@ -197,8 +198,9 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		err = pm_runtime_resume_and_get(pwmchip_parent(chip));
 		if (err)
 			return err;
-	} else
+	} else if (pc->soc->enable_reg == PWM_CSR_0) {
 		val |= PWM_ENABLE;
+	}
 
 	pwm_writel(pwm, PWM_CSR_0, val);
 
@@ -213,6 +215,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
+	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 	int rc = 0;
 	u32 val;
 
@@ -220,20 +223,22 @@ static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	if (rc)
 		return rc;
 
-	val = pwm_readl(pwm, PWM_CSR_0);
+
+	val = pwm_readl(pwm, pc->soc->enable_reg);
 	val |= PWM_ENABLE;
-	pwm_writel(pwm, PWM_CSR_0, val);
+	pwm_writel(pwm, pc->soc->enable_reg, val);
 
 	return 0;
 }
 
 static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
+	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 	u32 val;
 
-	val = pwm_readl(pwm, PWM_CSR_0);
+	val = pwm_readl(pwm, pc->soc->enable_reg);
 	val &= ~PWM_ENABLE;
-	pwm_writel(pwm, PWM_CSR_0, val);
+	pwm_writel(pwm, pc->soc->enable_reg, val);
 
 	pm_runtime_put_sync(pwmchip_parent(chip));
 }
@@ -398,10 +403,12 @@ static int __maybe_unused tegra_pwm_runtime_resume(struct device *dev)
 
 static const struct tegra_pwm_soc tegra20_pwm_soc = {
 	.num_channels = 4,
+	.enable_reg = PWM_CSR_0,
 };
 
 static const struct tegra_pwm_soc tegra186_pwm_soc = {
 	.num_channels = 1,
+	.enable_reg = PWM_CSR_0,
 };
 
 static const struct of_device_id tegra_pwm_of_match[] = {

-- 
2.53.0

[PATCH v2 5/7] pwm: tegra: Parametrize duty and scale field widths

[Mikko Perttunen]

Tegra264 has wider fields for the duty and scale register fields.
Parameterize the driver in preparation. The depth value also
becomes disconnected from the width of the duty field, so define
it separately.

Co-developed-by: Yi-Wei Wang <yiweiw@nvidia.com>
Signed-off-by: Yi-Wei Wang <yiweiw@nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
 drivers/pwm/pwm-tegra.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index 22d709986e8c..857301baad51 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/drivers/pwm/pwm-tegra.c
@@ -52,16 +52,19 @@
 #include <soc/tegra/common.h>
 
 #define PWM_ENABLE	(1 << 31)
-#define PWM_DUTY_WIDTH	8
 #define PWM_DUTY_SHIFT	16
-#define PWM_SCALE_WIDTH	13
 #define PWM_SCALE_SHIFT	0
 
 #define PWM_CSR_0	0
 
+#define PWM_DEPTH	256
+
 struct tegra_pwm_soc {
 	unsigned int num_channels;
 	unsigned int enable_reg;
+
+	unsigned int duty_width;
+	unsigned int scale_width;
 };
 
 struct tegra_pwm_chip {
@@ -106,22 +109,22 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	/*
 	 * Convert from duty_ns / period_ns to a fixed number of duty ticks
-	 * per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
+	 * per PWM_DEPTH cycles and make sure to round to the
 	 * nearest integer during division.
 	 */
-	c *= (1 << PWM_DUTY_WIDTH);
+	c *= PWM_DEPTH;
 	c = DIV_ROUND_CLOSEST_ULL(c, period_ns);
 
 	val = (u32)c << PWM_DUTY_SHIFT;
 
 	/*
-	 *  min period = max clock limit >> PWM_DUTY_WIDTH
+	 *  min period = max clock limit / PWM_DEPTH
 	 */
 	if (period_ns < pc->min_period_ns)
 		return -EINVAL;
 
 	/*
-	 * Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
+	 * Compute the prescaler value for which PWM_DEPTH
 	 * cycles at the PWM clock rate will take period_ns nanoseconds.
 	 *
 	 * num_channels: If single instance of PWM controller has multiple
@@ -135,7 +138,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	 */
 	if (pc->soc->num_channels == 1) {
 		/*
-		 * Rate is multiplied with 2^PWM_DUTY_WIDTH so that it matches
+		 * Rate is multiplied with PWM_DEPTH so that it matches
 		 * with the maximum possible rate that the controller can
 		 * provide. Any further lower value can be derived by setting
 		 * PFM bits[0:12].
@@ -145,7 +148,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		 * source clock rate as required_clk_rate, PWM controller will
 		 * be able to configure the requested period.
 		 */
-		required_clk_rate = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC << PWM_DUTY_WIDTH,
+		required_clk_rate = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC * PWM_DEPTH,
 						     period_ns);
 
 		if (required_clk_rate > clk_round_rate(pc->clk, required_clk_rate))
@@ -169,7 +172,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	/* Consider precision in PWM_SCALE_WIDTH rate calculation */
 	rate = mul_u64_u64_div_u64(pc->clk_rate, period_ns,
-				   (u64)NSEC_PER_SEC << PWM_DUTY_WIDTH);
+				   (u64)NSEC_PER_SEC * PWM_DEPTH);
 
 	/*
 	 * Since the actual PWM divider is the register's frequency divider
@@ -185,7 +188,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * Make sure that the rate will fit in the register's frequency
 	 * divider field.
 	 */
-	if (rate >> PWM_SCALE_WIDTH)
+	if (rate >> pc->soc->scale_width)
 		return -EINVAL;
 
 	val |= rate << PWM_SCALE_SHIFT;
@@ -324,7 +327,7 @@ static int tegra_pwm_probe(struct platform_device *pdev)
 
 	/* Set minimum limit of PWM period for the IP */
 	pc->min_period_ns =
-	    (NSEC_PER_SEC / (pc->clk_rate >> PWM_DUTY_WIDTH)) + 1;
+	    (NSEC_PER_SEC / (pc->clk_rate / PWM_DEPTH)) + 1;
 
 	pc->rst = devm_reset_control_get_exclusive(&pdev->dev, "pwm");
 	if (IS_ERR(pc->rst)) {
@@ -404,11 +407,15 @@ static int __maybe_unused tegra_pwm_runtime_resume(struct device *dev)
 static const struct tegra_pwm_soc tegra20_pwm_soc = {
 	.num_channels = 4,
 	.enable_reg = PWM_CSR_0,
+	.duty_width = 8,
+	.scale_width = 13,
 };
 
 static const struct tegra_pwm_soc tegra186_pwm_soc = {
 	.num_channels = 1,
 	.enable_reg = PWM_CSR_0,
+	.duty_width = 8,
+	.scale_width = 13,
 };
 
 static const struct of_device_id tegra_pwm_of_match[] = {

-- 
2.53.0

[PATCH v2 6/7] pwm: tegra: Add support for Tegra264

[Mikko Perttunen]

Tegra264 changes the register layout to accommodate wider fields
for duty and scale, and adds configurable depth which will be
supported in a later patch.

Add SoC data and update top comment to describe register layout
in more detail.

Co-developed-by: Yi-Wei Wang <yiweiw@nvidia.com>
Signed-off-by: Yi-Wei Wang <yiweiw@nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
 drivers/pwm/pwm-tegra.c | 75 ++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 61 insertions(+), 14 deletions(-)

diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index 857301baad51..c1e8a804d783 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/drivers/pwm/pwm-tegra.c
@@ -7,22 +7,60 @@
  * Copyright (c) 2010-2020, NVIDIA Corporation.
  * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
  *
- * Overview of Tegra Pulse Width Modulator Register:
- * 1. 13-bit: Frequency division (SCALE)
- * 2. 8-bit : Pulse division (DUTY)
- * 3. 1-bit : Enable bit
+ * Overview of Tegra Pulse Width Modulator Register
+ * CSR_0 of Tegra20, Tegra186, and Tegra194:
+ * +-------+-------+-----------------------------------------------------------+
+ * | Bit   | Field | Description                                               |
+ * +-------+-------+-----------------------------------------------------------+
+ * | 31    | ENB   | Enable Pulse width modulator.                             |
+ * |       |       | 0 = DISABLE, 1 = ENABLE.                                  |
+ * +-------+-------+-----------------------------------------------------------+
+ * | 30:16 | PWM_0 | Pulse width that needs to be programmed.                  |
+ * |       |       | 0 = Always low.                                           |
+ * |       |       | 1 = 1 / 256 pulse high.                                   |
+ * |       |       | 2 = 2 / 256 pulse high.                                   |
+ * |       |       | N = N / 256 pulse high.                                   |
+ * |       |       | Only 8 bits are usable [23:16].                           |
+ * |       |       | Bit[24] can be programmed to 1 to achieve 100% duty       |
+ * |       |       | cycle. In this case the other bits [23:16] are set to     |
+ * |       |       | don’t care.                                               |
+ * +-------+-------+-----------------------------------------------------------+
+ * | 12:0  | PFM_0 | Frequency divider that needs to be programmed, also known |
+ * |       |       | as SCALE. Division by (1 + PFM_0).                        |
+ * +-------+-------+-----------------------------------------------------------+
  *
- * The PWM clock frequency is divided by 256 before subdividing it based
- * on the programmable frequency division value to generate the required
- * frequency for PWM output. The maximum output frequency that can be
- * achieved is (max rate of source clock) / 256.
- * e.g. if source clock rate is 408 MHz, maximum output frequency can be:
- * 408 MHz/256 = 1.6 MHz.
- * This 1.6 MHz frequency can further be divided using SCALE value in PWM.
+ * CSR_0 of Tegra264:
+ * +-------+-------+-----------------------------------------------------------+
+ * | Bit   | Field | Description                                               |
+ * +-------+-------+-----------------------------------------------------------+
+ * | 31:16 | PWM_0 | Pulse width that needs to be programmed.                  |
+ * |       |       | 0 = Always low.                                           |
+ * |       |       | 1 = 1 / (1 + CSR_1.DEPTH) pulse high.                     |
+ * |       |       | 2 = 2 / (1 + CSR_1.DEPTH) pulse high.                     |
+ * |       |       | N = N / (1 + CSR_1.DEPTH) pulse high.                     |
+ * +-------+-------+-----------------------------------------------------------+
+ * | 15:0  | PFM_0 | Frequency divider that needs to be programmed, also known |
+ * |       |       | as SCALE. Division by (1 + PFM_0).                        |
+ * +-------+-------+-----------------------------------------------------------+
+ *
+ * CSR_1 of Tegra264:
+ * +-------+-------+-----------------------------------------------------------+
+ * | Bit   | Field | Description                                               |
+ * +-------+-------+-----------------------------------------------------------+
+ * | 31    | ENB   | Enable Pulse width modulator.                             |
+ * |       |       | 0 = DISABLE, 1 = ENABLE.                                  |
+ * +-------+-------+-----------------------------------------------------------+
+ * | 30:15 | DEPTH | Depth for pulse width modulator. This controls the pulse  |
+ * |       |       | time generated. Division by (1 + CSR_1.DEPTH).            |
+ * +-------+-------+-----------------------------------------------------------+
  *
- * PWM pulse width: 8 bits are usable [23:16] for varying pulse width.
- * To achieve 100% duty cycle, program Bit [24] of this register to
- * 1’b1. In which case the other bits [23:16] are set to don't care.
+ * The PWM clock frequency is divided by DEPTH = (1 + CSR_1.DEPTH) before subdividing it
+ * based on the programmable frequency division value to generate the required frequency
+ * for PWM output. DEPTH is fixed to 256 before Tegra264. The maximum output frequency
+ * that can be achieved is (max rate of source clock) / DEPTH.
+ * e.g. if source clock rate is 408 MHz, and DEPTH = 256, maximum output frequency can be:
+ * 408 MHz / 256 ~= 1.6 MHz.
+ * This 1.6 MHz frequency can further be divided using SCALE value in PWM.
  *
  * Limitations:
  * -	When PWM is disabled, the output is driven to inactive.
@@ -56,6 +94,7 @@
 #define PWM_SCALE_SHIFT	0
 
 #define PWM_CSR_0	0
+#define PWM_CSR_1	4
 
 #define PWM_DEPTH	256
 
@@ -418,10 +457,18 @@ static const struct tegra_pwm_soc tegra186_pwm_soc = {
 	.scale_width = 13,
 };
 
+static const struct tegra_pwm_soc tegra264_pwm_soc = {
+	.num_channels = 1,
+	.enable_reg = PWM_CSR_1,
+	.duty_width = 16,
+	.scale_width = 16,
+};
+
 static const struct of_device_id tegra_pwm_of_match[] = {
 	{ .compatible = "nvidia,tegra20-pwm", .data = &tegra20_pwm_soc },
 	{ .compatible = "nvidia,tegra186-pwm", .data = &tegra186_pwm_soc },
 	{ .compatible = "nvidia,tegra194-pwm", .data = &tegra186_pwm_soc },
+	{ .compatible = "nvidia,tegra264-pwm", .data = &tegra264_pwm_soc },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);

-- 
2.53.0

[PATCH v2 7/7] arm64: tegra: Add PWM controllers on Tegra264

[Mikko Perttunen]

From: Thierry Reding <treding@nvidia.com>

Tegra264 has a number of PWM controller which are similar to those found
on earlier chips but with some added functionality.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
---
 arch/arm64/boot/dts/nvidia/tegra264.dtsi | 72 ++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/arch/arm64/boot/dts/nvidia/tegra264.dtsi b/arch/arm64/boot/dts/nvidia/tegra264.dtsi
index 7644a41d5f72..13fd04068016 100644
--- a/arch/arm64/boot/dts/nvidia/tegra264.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra264.dtsi
@@ -3336,6 +3336,18 @@ i2c3: i2c@c610000 {
 			status = "disabled";
 		};
 
+		pwm4: pwm@c6a0000 {
+			compatible = "nvidia,tegra264-pwm";
+			reg = <0x0 0xc6a0000 0x0 0x10000>;
+			status = "disabled";
+
+			clocks = <&bpmp TEGRA264_CLK_PWM4>;
+			resets = <&bpmp TEGRA264_RESET_PWM4>;
+			reset-names = "pwm";
+
+			#pwm-cells = <2>;
+		};
+
 		pmc: pmc@c800000 {
 			compatible = "nvidia,tegra264-pmc";
 			reg = <0x0 0x0c800000 0x0 0x100000>,
@@ -3538,6 +3550,66 @@ i2c16: i2c@c430000 {
 			status = "disabled";
 		};
 
+		pwm2: pwm@c5e0000 {
+			compatible = "nvidia,tegra264-pwm";
+			reg = <0x0 0xc5e0000 0x0 0x10000>;
+			status = "disabled";
+
+			clocks = <&bpmp TEGRA264_CLK_PWM2>;
+			resets = <&bpmp TEGRA264_RESET_PWM2>;
+			reset-names = "pwm";
+
+			#pwm-cells = <2>;
+		};
+
+		pwm3: pwm@c5f0000 {
+			compatible = "nvidia,tegra264-pwm";
+			reg = <0x0 0xc5f0000 0x0 0x10000>;
+			status = "disabled";
+
+			clocks = <&bpmp TEGRA264_CLK_PWM3>;
+			resets = <&bpmp TEGRA264_RESET_PWM3>;
+			reset-names = "pwm";
+
+			#pwm-cells = <2>;
+		};
+
+		pwm5: pwm@c600000 {
+			compatible = "nvidia,tegra264-pwm";
+			reg = <0x0 0xc600000 0x0 0x10000>;
+			status = "disabled";
+
+			clocks = <&bpmp TEGRA264_CLK_PWM5>;
+			resets = <&bpmp TEGRA264_RESET_PWM5>;
+			reset-names = "pwm";
+
+			#pwm-cells = <2>;
+		};
+
+		pwm9: pwm@c610000 {
+			compatible = "nvidia,tegra264-pwm";
+			reg = <0x0 0xc610000 0x0 0x10000>;
+			status = "disabled";
+
+			clocks = <&bpmp TEGRA264_CLK_PWM9>;
+			resets = <&bpmp TEGRA264_RESET_PWM9>;
+			reset-names = "pwm";
+
+			#pwm-cells = <2>;
+		};
+
+		pwm10: pwm@c620000 {
+			compatible = "nvidia,tegra264-pwm";
+			reg = <0x0 0xc620000 0x0 0x10000>;
+			status = "disabled";
+
+			clocks = <&bpmp TEGRA264_CLK_PWM10>;
+			resets = <&bpmp TEGRA264_RESET_PWM10>;
+			reset-names = "pwm";
+
+			#pwm-cells = <2>;
+		};
+
 		i2c0: i2c@c630000 {
 			compatible = "nvidia,tegra264-i2c";
 			reg = <0x00 0x0c630000 0x0 0x10000>;

-- 
2.53.0

Re: [PATCH v2 1/7] dt-bindings: pwm: Document Tegra194 and Tegra264 controllers

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 2074 bytes --]

On Wed, Mar 25, 2026 at 07:16:59PM +0900, Mikko Perttunen wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> The PWM controller found on Tegra264 is largely compatible with the one
> on prior generations, but it comes with some extra features, hence a new
> compatible string is needed.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> ---
>  Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> index 41cea4979132..15706d2a808d 100644
> --- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> +++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> @@ -16,6 +16,8 @@ properties:
>        - enum:
>            - nvidia,tegra20-pwm
>            - nvidia,tegra186-pwm
> +          - nvidia,tegra194-pwm
> +          - nvidia,tegra264-pwm

I think this was lost during the earlier conversation we had on the
split of these patches. Krzysztof had pointed out that tegra194-pwm is
now a duplicate entry. I don't know exactly how it ended up like this,
but I'm pretty sure what I meant was:

	- items:
	    - const: tegra264-pwm
	    - const: tegra194-pwm

This mirrors the fact that this is in fact backwards-compatible with
Tegra194 but also has additional features that we need the Tegra264
compatible string for.

Krzysztof also requested that we drop the latter part of, or reword, the
commit message because we always want the compatible string to be added,
regardless of backwards-compatibility, etc.

So I think maybe something like this would be better for the commit
message:

  The PWM controller found on Tegra264 is largely compatible with the one
  on prior generations, but it comes with some extra features. The new
  Tegra264-specific compatible string can be used to distinguish between
  the feature sets.

Thierry

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Re: [PATCH v2 1/7] dt-bindings: pwm: Document Tegra194 and Tegra264 controllers

[Mikko Perttunen]

On 2026-03-25 15:22 +0100, Thierry Reding wrote:
> On Wed, Mar 25, 2026 at 07:16:59PM +0900, Mikko Perttunen wrote:
> > From: Thierry Reding <treding@nvidia.com>
> > 
> > The PWM controller found on Tegra264 is largely compatible with the one
> > on prior generations, but it comes with some extra features, hence a new
> > compatible string is needed.
> > 
> > Signed-off-by: Thierry Reding <treding@nvidia.com>
> > Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> > ---
> >  Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > index 41cea4979132..15706d2a808d 100644
> > --- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > +++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > @@ -16,6 +16,8 @@ properties:
> >        - enum:
> >            - nvidia,tegra20-pwm
> >            - nvidia,tegra186-pwm
> > +          - nvidia,tegra194-pwm
> > +          - nvidia,tegra264-pwm
> 
> I think this was lost during the earlier conversation we had on the
> split of these patches. Krzysztof had pointed out that tegra194-pwm is
> now a duplicate entry. I don't know exactly how it ended up like this,
> but I'm pretty sure what I meant was:
> 
> 	- items:
> 	    - const: tegra264-pwm
> 	    - const: tegra194-pwm

Ah, I see now.

> 
> This mirrors the fact that this is in fact backwards-compatible with
> Tegra194 but also has additional features that we need the Tegra264
> compatible string for.

The Tegra264 PWM controller is in fact not backwards compatible with
Tegra194. It is close but not quite. I will drop the duplicate tegra194
compatible string and update the commit message accordingly.

Mikko

> 
> Krzysztof also requested that we drop the latter part of, or reword, the
> commit message because we always want the compatible string to be added,
> regardless of backwards-compatibility, etc.
> 
> So I think maybe something like this would be better for the commit
> message:
> 
>   The PWM controller found on Tegra264 is largely compatible with the one
>   on prior generations, but it comes with some extra features. The new
>   Tegra264-specific compatible string can be used to distinguish between
>   the feature sets.
> 
> Thierry

Re: [PATCH v2 1/7] dt-bindings: pwm: Document Tegra194 and Tegra264 controllers

[Krzysztof Kozlowski]

On Wed, Mar 25, 2026 at 07:16:59PM +0900, Mikko Perttunen wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> The PWM controller found on Tegra264 is largely compatible with the one
> on prior generations, but it comes with some extra features, hence a new
> compatible string is needed.

Same comments as before.

Best regards,
Krzysztof

Re: [PATCH v2 1/7] dt-bindings: pwm: Document Tegra194 and Tegra264 controllers

[Krzysztof Kozlowski]

On Wed, Mar 25, 2026 at 03:22:13PM +0100, Thierry Reding wrote:
> On Wed, Mar 25, 2026 at 07:16:59PM +0900, Mikko Perttunen wrote:
> > From: Thierry Reding <treding@nvidia.com>
> > 
> > The PWM controller found on Tegra264 is largely compatible with the one
> > on prior generations, but it comes with some extra features, hence a new
> > compatible string is needed.
> > 
> > Signed-off-by: Thierry Reding <treding@nvidia.com>
> > Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> > ---
> >  Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > index 41cea4979132..15706d2a808d 100644
> > --- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > +++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > @@ -16,6 +16,8 @@ properties:
> >        - enum:
> >            - nvidia,tegra20-pwm
> >            - nvidia,tegra186-pwm
> > +          - nvidia,tegra194-pwm
> > +          - nvidia,tegra264-pwm
> 
> I think this was lost during the earlier conversation we had on the
> split of these patches. Krzysztof had pointed out that tegra194-pwm is
> now a duplicate entry. I don't know exactly how it ended up like this,
> but I'm pretty sure what I meant was:
> 
> 	- items:
> 	    - const: tegra264-pwm
> 	    - const: tegra194-pwm
> 
> This mirrors the fact that this is in fact backwards-compatible with
> Tegra194 but also has additional features that we need the Tegra264
> compatible string for.

If the devices are compatible. You have quite a lot of differences in
the driver, so the question is whether driver will work fine when bound
via old interface.

This was EXACTLY explained in DTS101 last year. I really focused on that
because after repeating for few years and two previous speeches people
still claim compatibility is something else. :(

Best regards,
Krzysztof

Re: [PATCH v2 2/7] pwm: tegra: Avoid hard-coded max clock frequency

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 743 bytes --]

On Wed, Mar 25, 2026 at 07:17:00PM +0900, Mikko Perttunen wrote:
> From: Yi-Wei Wang <yiweiw@nvidia.com>
> 
> The clock driving the Tegra PWM IP can be sourced from different parent
> clocks. Hence, let dev_pm_opp_set_rate() set the max clock rate based
> upon the current parent clock that can be specified via device-tree.
> 
> After this, the Tegra194 SoC data becomes redundant, so get rid of it.
> 
> Signed-off-by: Yi-Wei Wang <yiweiw@nvidia.com>
> Co-developed-by: Mikko Perttunen <mperttunen@nvidia.com>
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> ---
>  drivers/pwm/pwm-tegra.c | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)

Reviewed-by: Thierry Reding <treding@nvidia.com>

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Re: [PATCH v2 3/7] pwm: tegra: Modify read/write accessors for multi-register channel

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 526 bytes --]

On Wed, Mar 25, 2026 at 07:17:01PM +0900, Mikko Perttunen wrote:
> On Tegra264, each PWM instance has two registers (per channel, of which
> there is one). Update the pwm_readl/pwm_writel helper functions to
> take channel (as struct pwm_device *) and offset separately.
> 
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> ---
>  drivers/pwm/pwm-tegra.c | 26 +++++++++++++++-----------
>  1 file changed, 15 insertions(+), 11 deletions(-)

Makes sense:

Reviewed-by: Thierry Reding <treding@nvidia.com>

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Re: [PATCH v2 1/7] dt-bindings: pwm: Document Tegra194 and Tegra264 controllers

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 2196 bytes --]

On Thu, Mar 26, 2026 at 09:47:30AM +0900, Mikko Perttunen wrote:
> On 2026-03-25 15:22 +0100, Thierry Reding wrote:
> > On Wed, Mar 25, 2026 at 07:16:59PM +0900, Mikko Perttunen wrote:
> > > From: Thierry Reding <treding@nvidia.com>
> > > 
> > > The PWM controller found on Tegra264 is largely compatible with the one
> > > on prior generations, but it comes with some extra features, hence a new
> > > compatible string is needed.
> > > 
> > > Signed-off-by: Thierry Reding <treding@nvidia.com>
> > > Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> > > ---
> > >  Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > > index 41cea4979132..15706d2a808d 100644
> > > --- a/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > > +++ b/Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.yaml
> > > @@ -16,6 +16,8 @@ properties:
> > >        - enum:
> > >            - nvidia,tegra20-pwm
> > >            - nvidia,tegra186-pwm
> > > +          - nvidia,tegra194-pwm
> > > +          - nvidia,tegra264-pwm
> > 
> > I think this was lost during the earlier conversation we had on the
> > split of these patches. Krzysztof had pointed out that tegra194-pwm is
> > now a duplicate entry. I don't know exactly how it ended up like this,
> > but I'm pretty sure what I meant was:
> > 
> > 	- items:
> > 	    - const: tegra264-pwm
> > 	    - const: tegra194-pwm
> 
> Ah, I see now.
> 
> > 
> > This mirrors the fact that this is in fact backwards-compatible with
> > Tegra194 but also has additional features that we need the Tegra264
> > compatible string for.
> 
> The Tegra264 PWM controller is in fact not backwards compatible with
> Tegra194. It is close but not quite. I will drop the duplicate tegra194
> compatible string and update the commit message accordingly.

Ah... I remembered this wrongly. Yes, since the enable bit was moved to
a different register, we cannot claim backwards-compatibility.

Thierry

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Re: [PATCH v2 5/7] pwm: tegra: Parametrize duty and scale field widths

[Thierry Reding]

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On Wed, Mar 25, 2026 at 07:17:03PM +0900, Mikko Perttunen wrote:
> Tegra264 has wider fields for the duty and scale register fields.
> Parameterize the driver in preparation. The depth value also
> becomes disconnected from the width of the duty field, so define
> it separately.
> 
> Co-developed-by: Yi-Wei Wang <yiweiw@nvidia.com>
> Signed-off-by: Yi-Wei Wang <yiweiw@nvidia.com>
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> ---
>  drivers/pwm/pwm-tegra.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)

Reviewed-by: Thierry Reding <treding@nvidia.com>

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Re: [PATCH v2 4/7] pwm: tegra: Parametrize enable register offset

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1462 bytes --]

On Wed, Mar 25, 2026 at 07:17:02PM +0900, Mikko Perttunen wrote:
> On Tegra264, the PWM enablement bit is not located at the base address
> of the PWM controller. Hence, introduce an enablement offset field in
> the tegra_pwm_soc structure to describe the offset of the register.
> 
> Co-developed-by: Yi-Wei Wang <yiweiw@nvidia.com>
> Signed-off-by: Yi-Wei Wang <yiweiw@nvidia.com>
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> ---
>  drivers/pwm/pwm-tegra.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
> index cf54f75d92a5..22d709986e8c 100644
> --- a/drivers/pwm/pwm-tegra.c
> +++ b/drivers/pwm/pwm-tegra.c
> @@ -61,6 +61,7 @@
>  
>  struct tegra_pwm_soc {
>  	unsigned int num_channels;
> +	unsigned int enable_reg;
>  };
>  
>  struct tegra_pwm_chip {
> @@ -197,8 +198,9 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>  		err = pm_runtime_resume_and_get(pwmchip_parent(chip));
>  		if (err)
>  			return err;
> -	} else
> +	} else if (pc->soc->enable_reg == PWM_CSR_0) {
>  		val |= PWM_ENABLE;
> +	}

This looks incomplete for the Tegra264 case where

	pc->soc->enable_reg == PWM_CSR_1

>  
>  	pwm_writel(pwm, PWM_CSR_0, val);

I think we need another write for PWM_CSR_1 here to properly toggle the
PWM_ENABLE bit on Tegra264.

Or am I missing something?

Thierry

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