pwm: Add support for RP1 PWM

Add a driver for the RP1 PWM block.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

Documentation/devicetree/bindings/pwm/pwm-rp1.yaml

@@ -0,0 +1,38 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/pwm-rp1.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Raspberry Pi RP1 PWM controller
+
+maintainers:
+  - Naushir Patuck <naush@raspberrypi.com>
+
+properties:
+  compatible:
+    enum:
+      - raspberrypi,rp1-pwm
+
+  reg:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 3
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - "#pwm-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    pwm0: pwm@98000 {
+      compatible = "raspberrypi,rp1-pwm";
+      reg = <0x0 0x98000  0x0 0x100>;
+      clocks = <&rp1_sys>;
+      #pwm-cells = <3>;
+    };

drivers/pwm/Kconfig

@@ -483,6 +483,15 @@ config PWM_RASPBERRYPI_POE
 	  Enable Raspberry Pi firmware controller PWM bus used to control the
 	  official RPI PoE hat
 
+config PWM_RP1
+	tristate "RP1 PWM support"
+	depends on ARCH_BCM2835 || COMPILE_TEST
+	help
+	  PWM framework driver for Raspberry Pi RP1 controller
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-rp1.
+
 config PWM_RCAR
 	tristate "Renesas R-Car PWM support"
 	depends on ARCH_RENESAS || COMPILE_TEST

drivers/pwm/Makefile

@@ -44,6 +44,7 @@ obj-$(CONFIG_PWM_OMAP_DMTIMER)	+= pwm-omap-dmtimer.o
 obj-$(CONFIG_PWM_PCA9685)	+= pwm-pca9685.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
 obj-$(CONFIG_PWM_RASPBERRYPI_POE)	+= pwm-raspberrypi-poe.o
+obj-$(CONFIG_PWM_RP1)		+= pwm-rp1.o
 obj-$(CONFIG_PWM_RCAR)		+= pwm-rcar.o
 obj-$(CONFIG_PWM_RENESAS_TPU)	+= pwm-renesas-tpu.o
 obj-$(CONFIG_PWM_ROCKCHIP)	+= pwm-rockchip.o

drivers/pwm/pwm-rp1.c

@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * pwm-rp1.c
+ *
+ * Raspberry Pi RP1 PWM.
+ *
+ * Copyright © 2023 Raspberry Pi Ltd.
+ *
+ * Author: Naushir Patuck (naush@raspberrypi.com)
+ *
+ * Based on the pwm-bcm2835 driver by:
+ * Bart Tanghe <bart.tanghe@thomasmore.be>
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#define PWM_GLOBAL_CTRL		0x000
+#define PWM_CHANNEL_CTRL(x)	(0x014 + ((x) * 16))
+#define PWM_RANGE(x)		(0x018 + ((x) * 16))
+#define PWM_DUTY(x)		(0x020 + ((x) * 16))
+
+/* 8:FIFO_POP_MASK + 0:Trailing edge M/S modulation */
+#define PWM_CHANNEL_DEFAULT	(BIT(8) + BIT(0))
+#define PWM_CHANNEL_ENABLE(x)	BIT(x)
+#define PWM_POLARITY		BIT(3)
+#define SET_UPDATE		BIT(31)
+#define PWM_MODE_MASK		GENMASK(1, 0)
+
+struct rp1_pwm {
+	struct pwm_chip chip;
+	struct device *dev;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static inline struct rp1_pwm *to_rp1_pwm(struct pwm_chip *chip)
+{
+	return container_of(chip, struct rp1_pwm, chip);
+}
+
+static void rp1_pwm_apply_config(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct rp1_pwm *pc = to_rp1_pwm(chip);
+	u32 value;
+
+	value = readl(pc->base + PWM_GLOBAL_CTRL);
+	value |= SET_UPDATE;
+	writel(value, pc->base + PWM_GLOBAL_CTRL);
+}
+
+static int rp1_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct rp1_pwm *pc = to_rp1_pwm(chip);
+
+	writel(PWM_CHANNEL_DEFAULT, pc->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
+	return 0;
+}
+
+static void rp1_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct rp1_pwm *pc = to_rp1_pwm(chip);
+	u32 value;
+
+	value = readl(pc->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
+	value &= ~PWM_MODE_MASK;
+	writel(value, pc->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
+	rp1_pwm_apply_config(chip, pwm);
+}
+
+static int rp1_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			 const struct pwm_state *state)
+{
+	struct rp1_pwm *pc = to_rp1_pwm(chip);
+	unsigned long clk_rate = clk_get_rate(pc->clk);
+	unsigned long clk_period;
+	u32 value;
+
+	if (!clk_rate) {
+		dev_err(pc->dev, "failed to get clock rate\n");
+		return -EINVAL;
+	}
+
+	/* set period */
+	clk_period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, clk_rate);
+
+	writel(DIV_ROUND_CLOSEST(state->duty_cycle, clk_period),
+	       pc->base + PWM_DUTY(pwm->hwpwm));
+
+	/* set duty cycle */
+	writel(DIV_ROUND_CLOSEST(state->period, clk_period),
+	       pc->base + PWM_RANGE(pwm->hwpwm));
+
+	/* set polarity */
+	value = readl(pc->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
+	if (state->polarity == PWM_POLARITY_NORMAL)
+		value &= ~PWM_POLARITY;
+	else
+		value |= PWM_POLARITY;
+	writel(value, pc->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
+
+	/* enable/disable */
+	value = readl(pc->base + PWM_GLOBAL_CTRL);
+	if (state->enabled)
+		value |= PWM_CHANNEL_ENABLE(pwm->hwpwm);
+	else
+		value &= ~PWM_CHANNEL_ENABLE(pwm->hwpwm);
+	writel(value, pc->base + PWM_GLOBAL_CTRL);
+
+	rp1_pwm_apply_config(chip, pwm);
+
+	return 0;
+}
+
+static const struct pwm_ops rp1_pwm_ops = {
+	.request = rp1_pwm_request,
+	.free = rp1_pwm_free,
+	.apply = rp1_pwm_apply,
+};
+
+static int rp1_pwm_probe(struct platform_device *pdev)
+{
+	struct rp1_pwm *pc;
+	struct resource *res;
+	int ret;
+
+	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
+	if (!pc)
+		return -ENOMEM;
+
+	pc->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	pc->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(pc->base))
+		return PTR_ERR(pc->base);
+
+	pc->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(pc->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk),
+				     "clock not found\n");
+
+	ret = clk_prepare_enable(pc->clk);
+	if (ret)
+		return ret;
+
+	pc->chip.dev = &pdev->dev;
+	pc->chip.ops = &rp1_pwm_ops;
+	pc->chip.npwm = 4;
+	pc->chip.of_xlate = of_pwm_xlate_with_flags;
+
+	platform_set_drvdata(pdev, pc);
+
+	ret = pwmchip_add(&pc->chip);
+	if (ret < 0)
+		goto add_fail;
+
+	return 0;
+
+add_fail:
+	clk_disable_unprepare(pc->clk);
+	return ret;
+}
+
+static int rp1_pwm_remove(struct platform_device *pdev)
+{
+	struct rp1_pwm *pc = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(pc->clk);
+
+	pwmchip_remove(&pc->chip);
+
+	return 0;
+}
+
+static const struct of_device_id rp1_pwm_of_match[] = {
+	{ .compatible = "raspberrypi,rp1-pwm" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rp1_pwm_of_match);
+
+static struct platform_driver rp1_pwm_driver = {
+	.driver = {
+		.name = "rpi-pwm",
+		.of_match_table = rp1_pwm_of_match,
+	},
+	.probe = rp1_pwm_probe,
+	.remove = rp1_pwm_remove,
+};
+module_platform_driver(rp1_pwm_driver);
+
+MODULE_AUTHOR("Naushir Patuck <naush@raspberrypi.com");
+MODULE_DESCRIPTION("RP1 PWM driver");
+MODULE_LICENSE("GPL");