drivers: pwm: add driver for the NEORV32 PWM controller

Add driver for the NEORV32 PWM controller.

Signed-off-by: Henrik Brix Andersen <[email protected]>

Author: henrikbrixandersen

drivers/pwm/CMakeLists.txt

@@ -51,6 +51,7 @@ zephyr_library_sources_ifdef(CONFIG_PWM_RENESAS_RA	pwm_renesas_ra.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_INFINEON_CAT1	pwm_ifx_cat1.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_FAKE	pwm_fake.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_RENESAS_RZ_GPT	pwm_renesas_rz_gpt.c)
+zephyr_library_sources_ifdef(CONFIG_PWM_NEORV32	pwm_neorv32.c)
 zephyr_library_sources_ifdef(CONFIG_USERSPACE   pwm_handlers.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_CAPTURE pwm_capture.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_SHELL   pwm_shell.c)

drivers/pwm/Kconfig

@@ -124,4 +124,6 @@ source "drivers/pwm/Kconfig.renesas_rz"
 
 source "drivers/pwm/Kconfig.rts5912"
 
+source "drivers/pwm/Kconfig.neorv32"
+
 endif # PWM

drivers/pwm/Kconfig.neorv32

@@ -0,0 +1,12 @@
+# NEORV32 PWM configuration options
+
+# Copyright (c) 2025 Henrik Brix Andersen <[email protected]>
+# SPDX-License-Identifier: Apache-2.0
+
+config PWM_NEORV32
+	bool "NEORV32 PWM driver"
+	default y
+	depends on DT_HAS_NEORV32_PWM_ENABLED
+	depends on SYSCON
+	help
+	  Enable NEORV32 PWM driver.

drivers/pwm/pwm_neorv32.c

@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 2025 Henrik Brix Andersen <[email protected]>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT neorv32_pwm
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/pwm.h>
+#include <zephyr/drivers/syscon.h>
+#include <zephyr/sys/sys_io.h>
+#include <zephyr/sys/util.h>
+#include <zephyr/logging/log.h>
+
+#include <soc.h>
+
+LOG_MODULE_REGISTER(pwm_neorv32, CONFIG_PWM_LOG_LEVEL);
+
+/* NEORV32 PWM CHANNEL_CFG[0..15] register bits */
+#define NEORV32_PWM_CFG_EN   BIT(31)
+#define NEORV32_PWM_CFG_PRSC GENMASK(30, 28)
+#define NEORV32_PWM_CFG_POL  BIT(27)
+#define NEORV32_PWM_CFG_CDIV GENMASK(17, 8)
+#define NEORV32_PWM_CFG_DUTY GENMASK(7, 0)
+
+/* Maximum number of PWMs supported */
+#define NEORV32_PWM_CHANNELS 16
+
+struct neorv32_pwm_config {
+	const struct device *syscon;
+	mm_reg_t base;
+};
+
+static inline void neorv32_pwm_write_channel_cfg(const struct device *dev, uint8_t channel,
+						 uint32_t cfg)
+{
+	const struct neorv32_pwm_config *config = dev->config;
+
+	__ASSERT_NO_MSG(channel < NEORV32_PWM_CHANNELS);
+
+	sys_write32(cfg, config->base + (channel * sizeof(uint32_t)));
+}
+
+static int neorv32_pwm_set_cycles(const struct device *dev, uint32_t channel,
+				  uint32_t period_cycles, uint32_t pulse_cycles, pwm_flags_t flags)
+{
+	static const uint16_t cdiv_max = FIELD_GET(NEORV32_PWM_CFG_CDIV, NEORV32_PWM_CFG_CDIV);
+	static const uint16_t steps = FIELD_GET(NEORV32_PWM_CFG_DUTY, NEORV32_PWM_CFG_DUTY) + 1U;
+	static const uint16_t prsc_tbl[] = {2, 4, 8, 64, 128, 1024, 2048, 4096};
+	uint32_t cfg = 0U;
+	uint8_t duty = 0U;
+	uint16_t cdiv;
+	uint8_t prsc;
+
+	if (channel >= NEORV32_PWM_CHANNELS) {
+		LOG_ERR("invalid PWM channel %u", channel);
+		return -EINVAL;
+	}
+
+	if (pulse_cycles == 0U) {
+		/* Constant inactive level */
+		if ((flags & PWM_POLARITY_INVERTED) != 0U) {
+			cfg |= NEORV32_PWM_CFG_POL;
+		}
+	} else if (pulse_cycles == period_cycles) {
+		/* Constant active level */
+		if ((flags & PWM_POLARITY_INVERTED) == 0U) {
+			cfg |= NEORV32_PWM_CFG_POL;
+		}
+	} else {
+		/* PWM enabled */
+		if ((flags & PWM_POLARITY_INVERTED) != 0U) {
+			cfg |= NEORV32_PWM_CFG_POL;
+		}
+
+		for (prsc = 0; prsc < ARRAY_SIZE(prsc_tbl); prsc++) {
+			if (period_cycles / prsc_tbl[prsc] <= steps * (1U + cdiv_max)) {
+				break;
+			}
+		}
+
+		cdiv = DIV_ROUND_CLOSEST(DIV_ROUND_CLOSEST(period_cycles, prsc_tbl[prsc]), steps) -
+		       1U;
+
+		duty = CLAMP(DIV_ROUND_CLOSEST((uint64_t)(pulse_cycles * steps), period_cycles),
+			     1U, steps - 1U);
+
+		cfg |= NEORV32_PWM_CFG_EN | FIELD_PREP(NEORV32_PWM_CFG_PRSC, prsc) |
+		       FIELD_PREP(NEORV32_PWM_CFG_CDIV, cdiv) |
+		       FIELD_PREP(NEORV32_PWM_CFG_DUTY, duty);
+	}
+
+	neorv32_pwm_write_channel_cfg(dev, channel, cfg);
+
+	return 0;
+}
+
+static int neorv32_pwm_get_cycles_per_sec(const struct device *dev, uint32_t channel,
+					  uint64_t *cycles)
+{
+	const struct neorv32_pwm_config *config = dev->config;
+	uint32_t clk;
+	int err;
+
+	if (channel >= NEORV32_PWM_CHANNELS) {
+		LOG_ERR("invalid PWM channel %u", channel);
+		return -EINVAL;
+	}
+
+	err = syscon_read_reg(config->syscon, NEORV32_SYSINFO_CLK, &clk);
+	if (err < 0) {
+		LOG_ERR("failed to determine clock rate (err %d)", err);
+		return -EIO;
+	}
+
+	*cycles = clk;
+
+	return 0;
+}
+
+static int neorv32_pwm_init(const struct device *dev)
+{
+	const struct neorv32_pwm_config *config = dev->config;
+	uint32_t features;
+	int err;
+
+	if (!device_is_ready(config->syscon)) {
+		LOG_ERR("syscon device not ready");
+		return -EINVAL;
+	}
+
+	err = syscon_read_reg(config->syscon, NEORV32_SYSINFO_SOC, &features);
+	if (err < 0) {
+		LOG_ERR("failed to determine implemented features (err %d)", err);
+		return -EIO;
+	}
+
+	if ((features & NEORV32_SYSINFO_SOC_IO_PWM) == 0) {
+		LOG_ERR("neorv32 pwm not supported");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static DEVICE_API(pwm, neorv32_pwm_driver_api) = {
+	.set_cycles = neorv32_pwm_set_cycles,
+	.get_cycles_per_sec = neorv32_pwm_get_cycles_per_sec,
+};
+
+#define NEORV32_PWM_INIT(n)                                                                        \
+	static const struct neorv32_pwm_config neorv32_pwm_##n##_config = {                        \
+		.syscon = DEVICE_DT_GET(DT_INST_PHANDLE(n, syscon)),                               \
+		.base = DT_INST_REG_ADDR(n),                                                       \
+	};                                                                                         \
+                                                                                                   \
+	DEVICE_DT_INST_DEFINE(n, neorv32_pwm_init, NULL, NULL, &neorv32_pwm_##n##_config,          \
+			      POST_KERNEL, CONFIG_PWM_INIT_PRIORITY, &neorv32_pwm_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(NEORV32_PWM_INIT)