Add RP1 PWM controller support

PATCH Superseded Andrea della Porta 3 participants 8 messages Apr 23 – May 28

Subsystems (4)

Device tree bindings Broadcom BCM2711/BCM2835 Arm architecture PWM Raspberry pi RP1 PCI driver

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Andrea della Porta

author maintainer

2026-04-23 08:27 UTC #0 lore raw

v3 cover Add RP1 PWM controller support

This patchset adds support for the PWM controller found on the Raspberry Pi RP1 southbridge. This is necessary to operate the cooling fan connected to one of the PWM channels.

The tachometer pin for the fan speed is managed by the firmware running on the RP1's M-core. It uses the PHASE2 register to report the RPM, which is then exported by this driver via syscon registers. A subsequent patch will add a new device and driver to read the RPM and export this value via hwmon.

Subsequent patches will also add the CPU thermal zone, which acts as a consumer of the PWM device.

Best regards,
Andrea

CHANGES in V3:

- Refactored all the register macros. They now have RP1_PWM_ prefix and follow the register name.
- Dropped the tab alignment in front of struct declarations (use a space instead).
- Added a check in tohw() to test (and bail out quickly) in case that period_length_ns is zero.
- Probing now returns an error if clk_rate > 1 GHz.
- Added a check on minimum period ticks. Return 1 to signal round-up.
- Fixed inverted polarity detection on edge cases.
- Fixed rounding errors (in both tohwi() and fromhw()) in inverted polarity calculations.
- Dropped a redundant check on period >= duty.
- Replaced memset by inline struct init.
- Disabling a channel now is faster, skipping the duty/period/polarity setup.
- Fixed an error string (s/Fail/Failed)
- Used %pe to signal error string instead of an integer.
- Added several new sections to the Limitations paragraph to better explain what will happen on edge cases.
- Maximum period is now U32_MAX-1 to allow 100% duty cycle on all selectable periods.
- The hw period register now takes into account for the extra tick at the end of the period (subtracted one to wfhw->period_ticks in tohw and added 1 in fromhw).
- Added .remove() callback to free resources even if the driver is not unbindable/unloadable, to avoid accumulating tech debt.

Naushir Patuck (2):
dt-bindings: pwm: Add Raspberry Pi RP1 PWM controller
pwm: rp1: Add RP1 PWM controller driver

Stanimir Varbanov (1):
arm64: dts: broadcom: rpi-5: Add RP1 PWM node

 .../bindings/pwm/raspberrypi,rp1-pwm.yaml     |  54 +++
 .../boot/dts/broadcom/bcm2712-rpi-5-b.dts     |  12 +
 arch/arm64/boot/dts/broadcom/rp1-common.dtsi  |  10 +
 drivers/pwm/Kconfig                           |   9 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-rp1.c                         | 414 ++++++++++++++++++
 6 files changed, 500 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/raspberrypi,rp1-pwm.yaml
 create mode 100644 drivers/pwm/pwm-rp1.c

Signature · 1 line

2.35.3

Andrea della Porta

author maintainer

2026-04-23 08:27 UTC #1 lore raw

PATCH v3 1/3 dt-bindings: pwm: Add Raspberry Pi RP1 PWM controller

From: Naushir Patuck <[email protected]>

Add the devicetree binding documentation for the PWM controller found in the Raspberry Pi RP1 chipset.

Signed-off-by Naushir Patuck <[email protected]>

Co-developed-by Stanimir Varbanov <[email protected]>

Signed-off-by Stanimir Varbanov <[email protected]>

Signed-off-by Andrea della Porta <[email protected]>

Reviewed-by Krzysztof Kozlowski <[email protected]>

---
 .../bindings/pwm/raspberrypi,rp1-pwm.yaml     | 54 +++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/raspberrypi,rp1-pwm.yaml

Documentation/devicetree/bindings/pwm/raspberrypi,rp1-pwm.yaml new file +54 -0

new file mode 100644
index 0000000000000..6f8461d0454f7
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/raspberrypi,rp1-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Raspberry Pi RP1 PWM controller
+
+maintainers:
+  - Naushir Patuck <[email protected]>
+
+allOf:
+  - $ref: pwm.yaml#
+
+description: |
+  The PWM peripheral is a flexible waveform generator with a
+  variety of operational modes. It has the following features:
+   - four independent output channels
+   - 32-bit counter widths
+   - Seven output generation modes
+   - Optional per-channel output inversion
+   - Optional duty-cycle data FIFO with DMA support
+   - Optional sigma-delta noise shaping engine
+  Serves as a fan speed provider to other nodes for a PWM-connected
+  fan using shared registers (syscon).
+
+properties:
+  compatible:
+    const: raspberrypi,rp1-pwm
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 3
+
+required:
+  - compatible
+  - reg
+  - clocks
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    pwm@98000 {
+      compatible = "raspberrypi,rp1-pwm";
+      reg = <0x98000 0x100>;
+      clocks = <&rp1_clocks 17>;
+      #pwm-cells = <3>;
+    };

Signature · 1 line

2.35.3

Andrea della Porta

author maintainer

2026-04-23 08:27 UTC #2 lore raw

PATCH v3 2/3 pwm: rp1: Add RP1 PWM controller driver

In reply to Andrea della Porta

From: Naushir Patuck <[email protected]>

The Raspberry Pi RP1 southbridge features an embedded PWM controller with 4 output channels, alongside an RPM interface to read the fan speed on the Raspberry Pi 5.

Add the supporting driver.

Signed-off-by Naushir Patuck <[email protected]>

Co-developed-by Stanimir Varbanov <[email protected]>

Signed-off-by Stanimir Varbanov <[email protected]>

Signed-off-by Andrea della Porta <[email protected]>

---
 drivers/pwm/Kconfig   |   9 +
 drivers/pwm/Makefile  |   1 +
 drivers/pwm/pwm-rp1.c | 414 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 424 insertions(+)
 create mode 100644 drivers/pwm/pwm-rp1.c

drivers/pwm/Kconfig +9 -0

index 6f3147518376a..32031f2af75af 100644
@@ -625,6 +625,15 @@ config PWM_ROCKCHIP
 	  Generic PWM framework driver for the PWM controller found on
 	  Rockchip SoCs.
 
+config PWM_RASPBERRYPI_RP1
+	bool "RP1 PWM support"
+	depends on MISC_RP1 || COMPILE_TEST
+	depends on HAS_IOMEM
+	select REGMAP_MMIO
+	select MFD_SYSCON
+	help
+	  PWM framework driver for Raspberry Pi RP1 controller.
+
 config PWM_SAMSUNG
 	tristate "Samsung PWM support"
 	depends on PLAT_SAMSUNG || ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST

drivers/pwm/Makefile +1 -0

index 0dc0d2b69025d..59f29f60f9123 100644
@@ -56,6 +56,7 @@ obj-$(CONFIG_PWM_RENESAS_RZG2L_GPT)	+= pwm-rzg2l-gpt.o
 obj-$(CONFIG_PWM_RENESAS_RZ_MTU3)	+= pwm-rz-mtu3.o
 obj-$(CONFIG_PWM_RENESAS_TPU)	+= pwm-renesas-tpu.o
 obj-$(CONFIG_PWM_ROCKCHIP)	+= pwm-rockchip.o
+obj-$(CONFIG_PWM_RASPBERRYPI_RP1)	+= pwm-rp1.o
 obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_SIFIVE)	+= pwm-sifive.o
 obj-$(CONFIG_PWM_SL28CPLD)	+= pwm-sl28cpld.o

drivers/pwm/pwm-rp1.c new file +414 -0

414 lines not on this page · raw message

Signature · 1 line

2.35.3

Andrea della Porta

author maintainer

2026-04-23 08:27 UTC #3 lore raw

PATCH v3 3/3 arm64: dts: broadcom: rpi-5: Add RP1 PWM node

In reply to Andrea della Porta

From: Stanimir Varbanov <[email protected]>

The RP1 chipset used on the Raspberry Pi 5 features an integrated PWM controller to drive the cooling fan.

Add the corresponding DT node for this PWM controller.

Signed-off-by Stanimir Varbanov <[email protected]>

Co-developed-by Andrea della Porta <[email protected]>

Signed-off-by Andrea della Porta <[email protected]>

---
 arch/arm64/boot/dts/broadcom/bcm2712-rpi-5-b.dts | 12 ++++++++++++
 arch/arm64/boot/dts/broadcom/rp1-common.dtsi     | 10 ++++++++++
 2 files changed, 22 insertions(+)

arch/arm64/boot/dts/broadcom/bcm2712-rpi-5-b.dts +12 -0

index 2856082814462..a4e5ba23bf536 100644
@@ -64,12 +64,24 @@ phy1: ethernet-phy@1 {
 };
 
 &rp1_gpio {
+	fan_pwm_default_state: fan-pwm-default-state {
+		function = "pwm1";
+		pins = "gpio45";
+		bias-pull-down;
+	};
+
 	usb_vbus_default_state: usb-vbus-default-state {
 		function = "vbus1";
 		groups = "vbus1";
 	};
 };
 
+&rp1_pwm {
+	pinctrl-0 = <&fan_pwm_default_state>;
+	pinctrl-names = "default";
+	status = "okay";
+};
+
 &rp1_usb0 {
 	pinctrl-0 = <&usb_vbus_default_state>;
 	pinctrl-names = "default";

arch/arm64/boot/dts/broadcom/rp1-common.dtsi +10 -0

index 5a815c3797945..d0f4d6be75500 100644
@@ -26,6 +26,16 @@ rp1_clocks: clocks@40018000 {
 				       <200000000>;  // RP1_CLK_SYS
 	};
 
+	rp1_pwm: pwm@4009c000 {
+		compatible = "raspberrypi,rp1-pwm";
+		reg = <0x00 0x4009c000  0x0 0x100>;
+		clocks = <&rp1_clocks RP1_CLK_PWM1>;
+		assigned-clocks = <&rp1_clocks RP1_CLK_PWM1>;
+		assigned-clock-rates = <50000000>;
+		#pwm-cells = <3>;
+		status = "disabled";
+	};
+
 	rp1_gpio: pinctrl@400d0000 {
 		compatible = "raspberrypi,rp1-gpio";
 		reg = <0x00 0x400d0000  0x0 0xc000>,

Signature · 1 line

2.35.3

Andrea della Porta

author maintainer

2026-05-08 08:12 UTC #4 lore raw

In reply to Andrea della Porta

Hi Uwe,

Quoted 53 lines · Andrea della Porta

This patchset adds support for the PWM controller found on the Raspberry Pi RP1 southbridge. This is necessary to operate the cooling fan connected to one of the PWM channels.
The tachometer pin for the fan speed is managed by the firmware running on the RP1's M-core. It uses the PHASE2 register to report the RPM, which is then exported by this driver via syscon registers. A subsequent patch will add a new device and driver to read the RPM and export this value via hwmon.
Subsequent patches will also add the CPU thermal zone, which acts as a consumer of the PWM device.
Best regards,
Andrea
CHANGES in V3:
- Refactored all the register macros. They now have RP1_PWM_ prefix and follow the register name.
- Dropped the tab alignment in front of struct declarations (use a space instead).
- Added a check in tohw() to test (and bail out quickly) in case that period_length_ns is zero.
- Probing now returns an error if clk_rate > 1 GHz.
- Added a check on minimum period ticks. Return 1 to signal round-up.
- Fixed inverted polarity detection on edge cases.
- Fixed rounding errors (in both tohwi() and fromhw()) in inverted polarity calculations.
- Dropped a redundant check on period >= duty.
- Replaced memset by inline struct init.
- Disabling a channel now is faster, skipping the duty/period/polarity setup.
- Fixed an error string (s/Fail/Failed)
- Used %pe to signal error string instead of an integer.
- Added several new sections to the Limitations paragraph to better explain what will happen on edge cases.
- Maximum period is now U32_MAX-1 to allow 100% duty cycle on all selectable periods.
- The hw period register now takes into account for the extra tick at the end of the period (subtracted one to wfhw->period_ticks in tohw and added 1 in fromhw).
- Added .remove() callback to free resources even if the driver is not unbindable/unloadable, to avoid accumulating tech debt.
Naushir Patuck (2):
dt-bindings: pwm: Add Raspberry Pi RP1 PWM controller
pwm: rp1: Add RP1 PWM controller driver
Stanimir Varbanov (1):
arm64: dts: broadcom: rpi-5: Add RP1 PWM node

Quoted 13 lines

 .../bindings/pwm/raspberrypi,rp1-pwm.yaml     |  54 +++
 .../boot/dts/broadcom/bcm2712-rpi-5-b.dts     |  12 +
 arch/arm64/boot/dts/broadcom/rp1-common.dtsi  |  10 +
 drivers/pwm/Kconfig                           |   9 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-rp1.c                         | 414 ++++++++++++++++++
 6 files changed, 500 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/raspberrypi,rp1-pwm.yaml
 create mode 100644 drivers/pwm/pwm-rp1.c

Signature · 1 line

2.35.3

A gentle reminder about this patchset :)

Many thanks,
Andrea

Florian Fainelli

maintainer

2026-05-20 23:31 UTC #5 lore raw

Quoted 66 lines · Andrea della Porta

Hi Uwe,
Quoted 63 lines · Andrea della Porta
This patchset adds support for the PWM controller found on the Raspberry Pi RP1 southbridge. This is necessary to operate the cooling fan connected to one of the PWM channels.
The tachometer pin for the fan speed is managed by the firmware running on the RP1's M-core. It uses the PHASE2 register to report the RPM, which is then exported by this driver via syscon registers. A subsequent patch will add a new device and driver to read the RPM and export this value via hwmon.
Subsequent patches will also add the CPU thermal zone, which acts as a consumer of the PWM device.
Best regards,
Andrea
CHANGES in V3:
- Refactored all the register macros. They now have RP1_PWM_ prefix and follow the register name.
- Dropped the tab alignment in front of struct declarations (use a space instead).
- Added a check in tohw() to test (and bail out quickly) in case that period_length_ns is zero.
- Probing now returns an error if clk_rate > 1 GHz.
- Added a check on minimum period ticks. Return 1 to signal round-up.
- Fixed inverted polarity detection on edge cases.
- Fixed rounding errors (in both tohwi() and fromhw()) in inverted polarity calculations.
- Dropped a redundant check on period >= duty.
- Replaced memset by inline struct init.
- Disabling a channel now is faster, skipping the duty/period/polarity setup.
- Fixed an error string (s/Fail/Failed)
- Used %pe to signal error string instead of an integer.
- Added several new sections to the Limitations paragraph to better explain what will happen on edge cases.
- Maximum period is now U32_MAX-1 to allow 100% duty cycle on all selectable periods.
- The hw period register now takes into account for the extra tick at the end of the period (subtracted one to wfhw->period_ticks in tohw and added 1 in fromhw).
- Added .remove() callback to free resources even if the driver is not unbindable/unloadable, to avoid accumulating tech debt.
Naushir Patuck (2):
dt-bindings: pwm: Add Raspberry Pi RP1 PWM controller
pwm: rp1: Add RP1 PWM controller driver
Stanimir Varbanov (1):
arm64: dts: broadcom: rpi-5: Add RP1 PWM node
  .../bindings/pwm/raspberrypi,rp1-pwm.yaml     |  54 +++
  .../boot/dts/broadcom/bcm2712-rpi-5-b.dts     |  12 +
  arch/arm64/boot/dts/broadcom/rp1-common.dtsi  |  10 +
  drivers/pwm/Kconfig                           |   9 +
  drivers/pwm/Makefile                          |   1 +
  drivers/pwm/pwm-rp1.c                         | 414 ++++++++++++++++++
  6 files changed, 500 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/raspberrypi,rp1-pwm.yaml create mode 100644 drivers/pwm/pwm-rp1.c

Quoted 5 lines

Quoted 3 lines
Signature · 1 line
2.35.3
A gentle reminder about this patchset :)

Hi Uwe,

I would prefer to take the DTS changes through the Broadcom ARM SoC tree to minimize conflicts on my end, are you going to take the PWM patches for 7.2? Thanks!

Signature · 1 line

Florian

Uwe Kleine-König

maintainer

2026-05-27 07:55 UTC #6 lore raw

Hello,

Quoted 2 lines · Florian Fainelli

I would prefer to take the DTS changes through the Broadcom ARM SoC tree to minimize conflicts on my end, are you going to take the PWM patches for 7.2?

I didn't find the time yet to look in detail, but skimming
https://sashiko.dev/#/patchset/cover.1776932336.git.andrea.porta%40suse.com
suggests that there is still something to do for Andrea.

Best regards
Uwe

Andrea della Porta

author maintainer

2026-05-28 18:06 UTC #7 lore raw

Hi,

Quoted 9 lines · Uwe Kleine-König

Hello,
Quoted 2 lines · Florian Fainelli
I would prefer to take the DTS changes through the Broadcom ARM SoC tree to minimize conflicts on my end, are you going to take the PWM patches for 7.2?
I didn't find the time yet to look in detail, but skimming
https://sashiko.dev/#/patchset/cover.1776932336.git.andrea.porta%40suse.com
suggests that there is still something to do for Andrea.

Right, so I guess a V4 is on the way soon...
specifically, about teh DTS, I will rename rp1_pwm to rp1_pwm1 to differentiate it from pwm0.

Thanks,
Andrea

Quoted 3 lines

Best regards
Uwe