[PATCH v9 0/5] PWM and keyboard backlight driver for ARM Macs

[PATCH v9 0/5] PWM and keyboard backlight driver for ARM Macs

[Sasha Finkelstein via B4 Relay]

Hi,

This is the v9 of the patch series to add PWM and keyboard
backlight driver for ARM macs.

Changes in v1:
Addressing the review comments.

Changes in v2:
Added the reviewed-by and acked-by tags.
Addressing a review comment.

Changes in v3 and v4:
Addressing the review comments.

Changes in v5:
Added t600x device tree changes

Changes in v8:
Changed the overflow handling to clamp instead of erroring.

Changes in v9:
Missed a spot where clamping should be applied. Fixed that.

v1: https://www.spinics.net/lists/linux-pwm/msg19500.html
v2: https://www.spinics.net/lists/linux-pwm/msg19562.html
v3: https://www.spinics.net/lists/linux-pwm/msg19901.html
v4: https://www.spinics.net/lists/linux-pwm/msg20093.html
v5: https://www.spinics.net/lists/linux-pwm/msg20150.html
v6: https://www.spinics.net/lists/linux-pwm/msg20190.html
v7: https://lore.kernel.org/r/20230214-fpwm-v7-0-fb0a6bfbd037@gmail.com
v8: https://lore.kernel.org/r/20230214-fpwm-v8-0-65518a0d4944@gmail.com

---
Sasha Finkelstein (5):
      dt-bindings: pwm: Add Apple PWM controller
      pwm: Add Apple PWM controller
      arm64: dts: apple: t8103: Add PWM controller
      arm64: dts: apple: t600x: Add PWM controller
      MAINTAINERS: Add entries for Apple PWM driver

 .../devicetree/bindings/pwm/apple,s5l-fpwm.yaml    |  51 +++++++
 MAINTAINERS                                        |   2 +
 arch/arm64/boot/dts/apple/t600x-die0.dtsi          |   9 ++
 arch/arm64/boot/dts/apple/t600x-j314-j316.dtsi     |  18 +++
 arch/arm64/boot/dts/apple/t8103-j293.dts           |  17 +++
 arch/arm64/boot/dts/apple/t8103-j313.dts           |  17 +++
 arch/arm64/boot/dts/apple/t8103.dtsi               |   9 ++
 drivers/pwm/Kconfig                                |  12 ++
 drivers/pwm/Makefile                               |   1 +
 drivers/pwm/pwm-apple.c                            | 159 +++++++++++++++++++++
 10 files changed, 295 insertions(+)
---
base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
change-id: 20230214-fpwm-d8f76bc8ddc1

Best regards,
-- 
Sasha Finkelstein <fnkl.kernel@gmail.com>

[PATCH v9 1/5] dt-bindings: pwm: Add Apple PWM controller

[Sasha Finkelstein via B4 Relay]

From: Sasha Finkelstein <fnkl.kernel@gmail.com>

Apple SoCs such as the M1 contain a PWM controller used
among other things to control the keyboard backlight.

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Sven Peter <sven@svenpeter.dev>
---
 .../devicetree/bindings/pwm/apple,s5l-fpwm.yaml    | 51 ++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/Documentation/devicetree/bindings/pwm/apple,s5l-fpwm.yaml b/Documentation/devicetree/bindings/pwm/apple,s5l-fpwm.yaml
new file mode 100644
index 000000000000..142157bff0cd
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/apple,s5l-fpwm.yaml
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/apple,s5l-fpwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple FPWM controller
+
+maintainers:
+  - asahi@lists.linux.dev
+  - Sasha Finkelstein <fnkl.kernel@gmail.com>
+
+description: PWM controller used for keyboard backlight on ARM Macs
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - apple,t8103-fpwm
+          - apple,t6000-fpwm
+          - apple,t8112-fpwm
+      - const: apple,s5l-fpwm
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  power-domains:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 2
+
+required:
+  - compatible
+  - reg
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    pwm@235044000 {
+      compatible = "apple,t8103-fpwm", "apple,s5l-fpwm";
+      reg = <0x35044000 0x4000>;
+      power-domains = <&ps_fpwm1>;
+      clocks = <&clkref>;
+      #pwm-cells = <2>;
+    };

-- 
Git-137.1)

[PATCH v9 2/5] pwm: Add Apple PWM controller

[Sasha Finkelstein via B4 Relay]

From: Sasha Finkelstein <fnkl.kernel@gmail.com>

Adds the Apple PWM controller driver.

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Acked-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/Kconfig     |  12 ++++
 drivers/pwm/Makefile    |   1 +
 drivers/pwm/pwm-apple.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 172 insertions(+)

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index dae023d783a2..8df861b1f4a3 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -51,6 +51,18 @@ config PWM_AB8500
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-ab8500.
 
+config PWM_APPLE
+	tristate "Apple SoC PWM support"
+	depends on ARCH_APPLE || COMPILE_TEST
+	help
+	  Generic PWM framework driver for PWM controller present on
+	  Apple SoCs
+
+	  Say Y here if you have an ARM Apple laptop, otherwise say N
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-apple.
+
 config PWM_ATMEL
 	tristate "Atmel PWM support"
 	depends on ARCH_AT91 || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 7bf1a29f02b8..19899b912e00 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -2,6 +2,7 @@
 obj-$(CONFIG_PWM)		+= core.o
 obj-$(CONFIG_PWM_SYSFS)		+= sysfs.o
 obj-$(CONFIG_PWM_AB8500)	+= pwm-ab8500.o
+obj-$(CONFIG_PWM_APPLE)		+= pwm-apple.o
 obj-$(CONFIG_PWM_ATMEL)		+= pwm-atmel.o
 obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM)	+= pwm-atmel-hlcdc.o
 obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
diff --git a/drivers/pwm/pwm-apple.c b/drivers/pwm/pwm-apple.c
new file mode 100644
index 000000000000..a38a62edd713
--- /dev/null
+++ b/drivers/pwm/pwm-apple.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/*
+ * Driver for the Apple SoC PWM controller
+ *
+ * Copyright The Asahi Linux Contributors
+ *
+ * Limitations:
+ * - The writes to cycle registers are shadowed until a write to
+ *   the control register.
+ * - If both OFF_CYCLES and ON_CYCLES are set to 0, the output
+ *   is a constant off signal.
+ * - When APPLE_PWM_CTRL is set to 0, the output is constant low
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/math64.h>
+
+#define APPLE_PWM_CTRL        0x00
+#define APPLE_PWM_ON_CYCLES   0x1c
+#define APPLE_PWM_OFF_CYCLES  0x18
+
+#define APPLE_PWM_CTRL_ENABLE        BIT(0)
+#define APPLE_PWM_CTRL_MODE          BIT(2)
+#define APPLE_PWM_CTRL_UPDATE        BIT(5)
+#define APPLE_PWM_CTRL_TRIGGER       BIT(9)
+#define APPLE_PWM_CTRL_INVERT        BIT(10)
+#define APPLE_PWM_CTRL_OUTPUT_ENABLE BIT(14)
+
+struct apple_pwm {
+	struct pwm_chip chip;
+	void __iomem *base;
+	u64 clkrate;
+};
+
+static inline struct apple_pwm *to_apple_pwm(struct pwm_chip *chip)
+{
+	return container_of(chip, struct apple_pwm, chip);
+}
+
+static int apple_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			   const struct pwm_state *state)
+{
+	struct apple_pwm *fpwm;
+
+	if (state->polarity == PWM_POLARITY_INVERSED)
+		return -EINVAL;
+
+	fpwm = to_apple_pwm(chip);
+	if (state->enabled) {
+		u64 on_cycles, off_cycles;
+
+		on_cycles = mul_u64_u64_div_u64(fpwm->clkrate,
+						state->duty_cycle, NSEC_PER_SEC);
+		if (on_cycles > 0xFFFFFFFF)
+			on_cycles = 0xFFFFFFFF;
+
+		off_cycles = mul_u64_u64_div_u64(fpwm->clkrate,
+						 state->period, NSEC_PER_SEC) - on_cycles;
+		if (off_cycles > 0xFFFFFFFF)
+			off_cycles = 0xFFFFFFFF;
+
+		writel(on_cycles, fpwm->base + APPLE_PWM_ON_CYCLES);
+		writel(off_cycles, fpwm->base + APPLE_PWM_OFF_CYCLES);
+		writel(APPLE_PWM_CTRL_ENABLE | APPLE_PWM_CTRL_OUTPUT_ENABLE | APPLE_PWM_CTRL_UPDATE,
+		       fpwm->base + APPLE_PWM_CTRL);
+	} else {
+		writel(0, fpwm->base + APPLE_PWM_CTRL);
+	}
+	return 0;
+}
+
+static int apple_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			   struct pwm_state *state)
+{
+	struct apple_pwm *fpwm;
+	u32 on_cycles, off_cycles, ctrl;
+
+	fpwm = to_apple_pwm(chip);
+
+	ctrl = readl(fpwm->base + APPLE_PWM_CTRL);
+	on_cycles = readl(fpwm->base + APPLE_PWM_ON_CYCLES);
+	off_cycles = readl(fpwm->base + APPLE_PWM_OFF_CYCLES);
+
+	state->enabled = (ctrl & APPLE_PWM_CTRL_ENABLE) && (ctrl & APPLE_PWM_CTRL_OUTPUT_ENABLE);
+	state->polarity = PWM_POLARITY_NORMAL;
+	// on_cycles + off_cycles is 33 bits, NSEC_PER_SEC is 30, there is no overflow
+	state->duty_cycle = DIV64_U64_ROUND_UP((u64)on_cycles * NSEC_PER_SEC, fpwm->clkrate);
+	state->period = DIV64_U64_ROUND_UP(((u64)off_cycles + (u64)on_cycles) *
+					    NSEC_PER_SEC, fpwm->clkrate);
+
+	return 0;
+}
+
+static const struct pwm_ops apple_pwm_ops = {
+	.apply = apple_pwm_apply,
+	.get_state = apple_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
+static int apple_pwm_probe(struct platform_device *pdev)
+{
+	struct apple_pwm *fpwm;
+	struct clk *clk;
+	int ret;
+
+	fpwm = devm_kzalloc(&pdev->dev, sizeof(*fpwm), GFP_KERNEL);
+	if (!fpwm)
+		return -ENOMEM;
+
+	fpwm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(fpwm->base))
+		return PTR_ERR(fpwm->base);
+
+	clk = devm_clk_get_enabled(&pdev->dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(clk), "unable to get the clock");
+
+	/*
+	 * Uses the 24MHz system clock on all existing devices, can only
+	 * happen if the device tree is broken
+	 *
+	 * This check is done to prevent an overflow in .apply
+	 */
+	fpwm->clkrate = clk_get_rate(clk);
+	if (fpwm->clkrate > NSEC_PER_SEC)
+		return dev_err_probe(&pdev->dev, -EINVAL, "pwm clock out of range");
+
+	fpwm->chip.dev = &pdev->dev;
+	fpwm->chip.npwm = 1;
+	fpwm->chip.ops = &apple_pwm_ops;
+
+	ret = devm_pwmchip_add(&pdev->dev, &fpwm->chip);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "unable to add pwm chip");
+
+	return 0;
+}
+
+static const struct of_device_id apple_pwm_of_match[] = {
+	{ .compatible = "apple,s5l-fpwm" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, apple_pwm_of_match);
+
+static struct platform_driver apple_pwm_driver = {
+	.probe = apple_pwm_probe,
+	.driver = {
+		.name = "apple-pwm",
+		.of_match_table = apple_pwm_of_match,
+	},
+};
+module_platform_driver(apple_pwm_driver);
+
+MODULE_DESCRIPTION("Apple SoC PWM driver");
+MODULE_LICENSE("Dual MIT/GPL");

-- 
Git-137.1)

[PATCH v9 3/5] arm64: dts: apple: t8103: Add PWM controller

[Sasha Finkelstein via B4 Relay]

From: Sasha Finkelstein <fnkl.kernel@gmail.com>

Adds PWM controller and keyboard backlight bindings for M1 MacBooks

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Acked-by: Sven Peter <sven@svenpeter.dev>
---
 arch/arm64/boot/dts/apple/t8103-j293.dts | 17 +++++++++++++++++
 arch/arm64/boot/dts/apple/t8103-j313.dts | 17 +++++++++++++++++
 arch/arm64/boot/dts/apple/t8103.dtsi     |  9 +++++++++
 3 files changed, 43 insertions(+)

diff --git a/arch/arm64/boot/dts/apple/t8103-j293.dts b/arch/arm64/boot/dts/apple/t8103-j293.dts
index 151074109a11..fc55ce0fa40d 100644
--- a/arch/arm64/boot/dts/apple/t8103-j293.dts
+++ b/arch/arm64/boot/dts/apple/t8103-j293.dts
@@ -11,10 +11,23 @@
 
 #include "t8103.dtsi"
 #include "t8103-jxxx.dtsi"
+#include <dt-bindings/leds/common.h>
 
 / {
 	compatible = "apple,j293", "apple,t8103", "apple,arm-platform";
 	model = "Apple MacBook Pro (13-inch, M1, 2020)";
+
+	led-controller {
+		compatible = "pwm-leds";
+		led-0 {
+			pwms = <&fpwm1 0 40000>;
+			label = "kbd_backlight";
+			function = LED_FUNCTION_KBD_BACKLIGHT;
+			color = <LED_COLOR_ID_WHITE>;
+			max-brightness = <255>;
+			default-state = "keep";
+		};
+	};
 };
 
 &bluetooth0 {
@@ -47,3 +60,7 @@ &i2c2 {
 &i2c4 {
 	status = "okay";
 };
+
+&fpwm1 {
+	status = "okay";
+};
diff --git a/arch/arm64/boot/dts/apple/t8103-j313.dts b/arch/arm64/boot/dts/apple/t8103-j313.dts
index bc1f865aa790..1e26aa1ef525 100644
--- a/arch/arm64/boot/dts/apple/t8103-j313.dts
+++ b/arch/arm64/boot/dts/apple/t8103-j313.dts
@@ -11,10 +11,23 @@
 
 #include "t8103.dtsi"
 #include "t8103-jxxx.dtsi"
+#include <dt-bindings/leds/common.h>
 
 / {
 	compatible = "apple,j313", "apple,t8103", "apple,arm-platform";
 	model = "Apple MacBook Air (M1, 2020)";
+
+	led-controller {
+		compatible = "pwm-leds";
+		led-0 {
+			pwms = <&fpwm1 0 40000>;
+			label = "kbd_backlight";
+			function = LED_FUNCTION_KBD_BACKLIGHT;
+			color = <LED_COLOR_ID_WHITE>;
+			max-brightness = <255>;
+			default-state = "keep";
+		};
+	};
 };
 
 &bluetooth0 {
@@ -39,3 +52,7 @@ &pcie0_dart_2 {
 
 /delete-node/ &port01;
 /delete-node/ &port02;
+
+&fpwm1 {
+	status = "okay";
+};
diff --git a/arch/arm64/boot/dts/apple/t8103.dtsi b/arch/arm64/boot/dts/apple/t8103.dtsi
index 9859219699f4..5300fd115561 100644
--- a/arch/arm64/boot/dts/apple/t8103.dtsi
+++ b/arch/arm64/boot/dts/apple/t8103.dtsi
@@ -432,6 +432,15 @@ i2c4: i2c@235020000 {
 			status = "disabled"; /* only used in J293 */
 		};
 
+		fpwm1: pwm@235044000 {
+			compatible = "apple,t8103-fpwm", "apple,s5l-fpwm";
+			reg = <0x2 0x35044000 0x0 0x4000>;
+			power-domains = <&ps_fpwm1>;
+			clocks = <&clkref>;
+			#pwm-cells = <2>;
+			status = "disabled";
+		};
+
 		serial0: serial@235200000 {
 			compatible = "apple,s5l-uart";
 			reg = <0x2 0x35200000 0x0 0x1000>;

-- 
Git-137.1)

[PATCH v9 4/5] arm64: dts: apple: t600x: Add PWM controller

[Sasha Finkelstein via B4 Relay]

From: Sasha Finkelstein <7d578vix8hzw@opayq.net>

Adds PWM controller and keyboard backlight bindings for M1 Pro/Max MacBook Pros

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Acked-by: Hector Martin <marcan@marcan.st>
---
 arch/arm64/boot/dts/apple/t600x-die0.dtsi      |  9 +++++++++
 arch/arm64/boot/dts/apple/t600x-j314-j316.dtsi | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/arch/arm64/boot/dts/apple/t600x-die0.dtsi b/arch/arm64/boot/dts/apple/t600x-die0.dtsi
index 1c41954e3899..9157ae2a9f7f 100644
--- a/arch/arm64/boot/dts/apple/t600x-die0.dtsi
+++ b/arch/arm64/boot/dts/apple/t600x-die0.dtsi
@@ -71,6 +71,15 @@ sio_dart_1: iommu@39b008000 {
 		power-domains = <&ps_sio_cpu>;
 	};
 
+	fpwm0: pwm@39b030000 {
+		compatible = "apple,t6000-fpwm", "apple,s5l-fpwm";
+		reg = <0x3 0x9b030000 0x0 0x4000>;
+		power-domains = <&ps_fpwm0>;
+		clocks = <&clkref>;
+		#pwm-cells = <2>;
+		status = "disabled";
+	};
+
 	i2c0: i2c@39b040000 {
 		compatible = "apple,t6000-i2c", "apple,i2c";
 		reg = <0x3 0x9b040000 0x0 0x4000>;
diff --git a/arch/arm64/boot/dts/apple/t600x-j314-j316.dtsi b/arch/arm64/boot/dts/apple/t600x-j314-j316.dtsi
index 34906d522f0a..96de7165df6d 100644
--- a/arch/arm64/boot/dts/apple/t600x-j314-j316.dtsi
+++ b/arch/arm64/boot/dts/apple/t600x-j314-j316.dtsi
@@ -9,6 +9,8 @@
  * Copyright The Asahi Linux Contributors
  */
 
+#include <dt-bindings/leds/common.h>
+
 / {
 	aliases {
 		serial0 = &serial0;
@@ -34,6 +36,18 @@ memory@10000000000 {
 		device_type = "memory";
 		reg = <0x100 0 0x2 0>; /* To be filled by loader */
 	};
+
+	led-controller {
+		compatible = "pwm-leds";
+		led-0 {
+			pwms = <&fpwm0 0 40000>;
+			label = "kbd_backlight";
+			function = LED_FUNCTION_KBD_BACKLIGHT;
+			color = <LED_COLOR_ID_WHITE>;
+			max-brightness = <255>;
+			default-state = "keep";
+		};
+	};
 };
 
 &serial0 {
@@ -110,5 +124,9 @@ &pcie0_dart_3 {
 	status = "disabled";
 };
 
+&fpwm0 {
+	status = "okay";
+};
+
 /delete-node/ &port02;
 /delete-node/ &port03;

-- 
Git-137.1)

[PATCH v9 5/5] MAINTAINERS: Add entries for Apple PWM driver

[Sasha Finkelstein via B4 Relay]

From: Sasha Finkelstein <fnkl.kernel@gmail.com>

Add the MAINTAINERS entries for the driver

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Acked-by: Sven Peter <sven@svenpeter.dev>
---
 MAINTAINERS | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 8d5bc223f305..7c0b7c2bb55f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1955,6 +1955,7 @@ F:	Documentation/devicetree/bindings/nvmem/apple,efuses.yaml
 F:	Documentation/devicetree/bindings/pci/apple,pcie.yaml
 F:	Documentation/devicetree/bindings/pinctrl/apple,pinctrl.yaml
 F:	Documentation/devicetree/bindings/power/apple*
+F:	Documentation/devicetree/bindings/pwm/pwm-apple.yaml
 F:	Documentation/devicetree/bindings/watchdog/apple,wdt.yaml
 F:	arch/arm64/boot/dts/apple/
 F:	drivers/bluetooth/hci_bcm4377.c
@@ -1970,6 +1971,7 @@ F:	drivers/mailbox/apple-mailbox.c
 F:	drivers/nvme/host/apple.c
 F:	drivers/nvmem/apple-efuses.c
 F:	drivers/pinctrl/pinctrl-apple-gpio.c
+F:	drivers/pwm/pwm-apple.c
 F:	drivers/soc/apple/*
 F:	drivers/watchdog/apple_wdt.c
 F:	include/dt-bindings/interrupt-controller/apple-aic.h

-- 
Git-137.1)

[PATCH v9 1/5] dt-bindings: pwm: Add Apple PWM controller

[Sasha Finkelstein via B4 Relay]

From: Sasha Finkelstein <fnkl.kernel@gmail.com>

Apple SoCs such as the M1 contain a PWM controller used
among other things to control the keyboard backlight.

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Sven Peter <sven@svenpeter.dev>
---
 .../devicetree/bindings/pwm/apple,s5l-fpwm.yaml    | 51 ++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/Documentation/devicetree/bindings/pwm/apple,s5l-fpwm.yaml b/Documentation/devicetree/bindings/pwm/apple,s5l-fpwm.yaml
new file mode 100644
index 000000000000..142157bff0cd
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/apple,s5l-fpwm.yaml
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/apple,s5l-fpwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple FPWM controller
+
+maintainers:
+  - asahi@lists.linux.dev
+  - Sasha Finkelstein <fnkl.kernel@gmail.com>
+
+description: PWM controller used for keyboard backlight on ARM Macs
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - apple,t8103-fpwm
+          - apple,t6000-fpwm
+          - apple,t8112-fpwm
+      - const: apple,s5l-fpwm
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  power-domains:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 2
+
+required:
+  - compatible
+  - reg
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    pwm@235044000 {
+      compatible = "apple,t8103-fpwm", "apple,s5l-fpwm";
+      reg = <0x35044000 0x4000>;
+      power-domains = <&ps_fpwm1>;
+      clocks = <&clkref>;
+      #pwm-cells = <2>;
+    };

-- 
Git-137.1)