drivers: pwm: add pwm driver for rpi_pico

Add pwm driver implementation for rpi pico family.
Adds myself as codeowner of drivers/pwm/*rpi_pico*

Signed-off-by: Joep Buruma <burumaj50@gmail.com>

CODEOWNERS

@@ -344,6 +344,7 @@
 /drivers/ps2/*xec*                        @franciscomunoz @sjvasanth1
 /drivers/ps2/*npcx*                       @MulinChao @WealianLiao @ChiHuaL
 /drivers/pwm/*b91*                        @andy-liu-telink
+/drivers/pwm/*rpi_pico*                   @burumaj
 /drivers/pwm/*rv32m1*                     @henrikbrixandersen
 /drivers/pwm/*sam0*                       @nzmichaelh
 /drivers/pwm/*stm32*                      @gmarull

drivers/pwm/CMakeLists.txt

@@ -25,6 +25,7 @@ zephyr_library_sources_ifdef(CONFIG_PWM_MCUX_PWT 	pwm_mcux_pwt.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_GECKO		pwm_gecko.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_GD32		pwm_gd32.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_TEST		pwm_test.c)
+zephyr_library_sources_ifdef(CONFIG_PWM_RPI_PICO	pwm_rpi_pico.c)
 
 zephyr_library_sources_ifdef(CONFIG_USERSPACE   pwm_handlers.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_CAPTURE pwm_capture.c)

drivers/pwm/Kconfig

@@ -73,4 +73,6 @@ source "drivers/pwm/Kconfig.gd32"
 
 source "drivers/pwm/Kconfig.test"
 
+source "drivers/pwm/Kconfig.rpi_pico"
+
 endif # PWM

drivers/pwm/Kconfig.rpi_pico

@@ -0,0 +1,14 @@
+# Copyright (c) 2022, Joep Buruma
+# SPDX-License-Identifier: Apache-2.0
+
+# Workaround for not being able to have commas in macro arguments
+DT_COMPAT_RPI_PICO_PWM := raspberrypi,pico-pwm
+
+config PWM_RPI_PICO
+	bool "RPi Pico PWM"
+	default $(dt_compat_enabled,$(DT_COMPAT_RPI_PICO_PWM))
+	depends on SOC_SERIES_RP2XXX
+	depends on RESET
+	select PICOSDK_USE_PWM
+	help
+	  Enable PWM driver for RPi Pico family of MCUs

drivers/pwm/pwm_rpi_pico.c

@@ -0,0 +1,182 @@
+/*
+ * Copyright (c) 2022, Joep Buruma
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#define DT_DRV_COMPAT raspberrypi_pico_pwm
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/pwm.h>
+#include <zephyr/drivers/pinctrl.h>
+#include <zephyr/drivers/reset.h>
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(pwm_rpi_pico, CONFIG_PWM_LOG_LEVEL);
+
+/* pico-sdk includes */
+#include <hardware/pwm.h>
+#include <hardware/structs/pwm.h>
+
+#define PWM_RPI_PICO_COUNTER_TOP_MAX    UINT16_MAX
+#define PWM_RPI_NUM_CHANNELS            (16U)
+
+struct pwm_rpi_slice_config {
+	uint8_t integral;
+	uint8_t frac;
+	bool phase_correct;
+};
+
+struct pwm_rpi_config {
+	/*
+	 * pwm_controller is the start address of the pwm peripheral.
+	 */
+	pwm_hw_t *pwm_controller;
+	struct pwm_rpi_slice_config slice_configs[NUM_PWM_SLICES];
+	const struct pinctrl_dev_config *pcfg;
+	const struct reset_dt_spec reset;
+};
+
+static float pwm_rpi_get_clkdiv(const struct device *dev, int slice)
+{
+	const struct pwm_rpi_config *cfg = dev->config;
+
+	/* the divider is a fixed point 8.4 convert to float for use in pico-sdk */
+	return (float)cfg->slice_configs[slice].integral +
+		(float)cfg->slice_configs[slice].frac / 16.0;
+}
+
+static inline uint32_t pwm_rpi_channel_to_slice(uint32_t channel)
+{
+	return channel / 2;
+}
+
+static inline uint32_t pwm_rpi_channel_to_pico_channel(uint32_t channel)
+{
+	return channel % 2;
+}
+
+static int pwm_rpi_get_cycles_per_sec(const struct device *dev, uint32_t ch, uint64_t *cycles)
+{
+	float f_clock_in;
+	int slice = pwm_rpi_channel_to_slice(ch);
+
+	if (ch >= PWM_RPI_NUM_CHANNELS) {
+		return -EINVAL;
+	}
+
+	f_clock_in = (float)sys_clock_hw_cycles_per_sec();
+
+	/* No need to check for divide by 0 since the minimum value of
+	 * pwm_rpi_get_clkdiv is 1
+	 */
+	*cycles = (uint64_t)(f_clock_in / pwm_rpi_get_clkdiv(dev, slice));
+	return 0;
+}
+
+/* The pico_sdk only allows setting the polarity of both channels at once.
+ * This is a convenience function to make setting the polarity of a single
+ * channel easier.
+ */
+static void pwm_rpi_set_channel_polarity(const struct device *dev, int slice,
+					 int pico_channel, bool inverted)
+{
+	const struct pwm_rpi_config *cfg = dev->config;
+
+	bool pwm_polarity_a = (cfg->pwm_controller->slice[slice].csr & PWM_CH0_CSR_A_INV_BITS) > 0;
+	bool pwm_polarity_b = (cfg->pwm_controller->slice[slice].csr & PWM_CH0_CSR_B_INV_BITS) > 0;
+
+	if (pico_channel == PWM_CHAN_A) {
+		pwm_polarity_a = inverted;
+	} else if (pico_channel == PWM_CHAN_B) {
+		pwm_polarity_b = inverted;
+	}
+
+	pwm_set_output_polarity(slice, pwm_polarity_a, pwm_polarity_b);
+}
+
+static int pwm_rpi_set_cycles(const struct device *dev, uint32_t ch, uint32_t period_cycles,
+			   uint32_t pulse_cycles, pwm_flags_t flags)
+{
+	if (ch >= PWM_RPI_NUM_CHANNELS) {
+		return -EINVAL;
+	}
+
+	if (period_cycles > PWM_RPI_PICO_COUNTER_TOP_MAX ||
+	    pulse_cycles > PWM_RPI_PICO_COUNTER_TOP_MAX) {
+		return -EINVAL;
+	}
+
+	int slice = pwm_rpi_channel_to_slice(ch);
+
+	/* this is the channel within a pwm slice */
+	int pico_channel = pwm_rpi_channel_to_pico_channel(ch);
+
+	pwm_rpi_set_channel_polarity(dev, slice, pico_channel,
+				     (flags & PWM_POLARITY_MASK) == PWM_POLARITY_INVERTED);
+	pwm_set_wrap(slice, period_cycles);
+	pwm_set_chan_level(slice, ch, pulse_cycles);
+
+	return 0;
+};
+
+struct pwm_driver_api pwm_rpi_driver_api = {
+	.get_cycles_per_sec = pwm_rpi_get_cycles_per_sec,
+	.set_cycles = pwm_rpi_set_cycles,
+};
+
+static int pwm_rpi_init(const struct device *dev)
+{
+	const struct pwm_rpi_config *cfg = dev->config;
+	pwm_config slice_cfg;
+	size_t slice_idx;
+	int err;
+
+	err = pinctrl_apply_state(cfg->pcfg, PINCTRL_STATE_DEFAULT);
+	if (err) {
+		LOG_ERR("Failed to configure pins for PWM. err=%d", err);
+		return err;
+	}
+
+	for (slice_idx = 0; slice_idx < NUM_PWM_SLICES; slice_idx++) {
+		slice_cfg = pwm_get_default_config();
+		pwm_config_set_clkdiv_mode(&slice_cfg, PWM_DIV_FREE_RUNNING);
+
+		pwm_init(slice_idx, &slice_cfg, false);
+
+		pwm_set_clkdiv_int_frac(slice_idx,
+					cfg->slice_configs[slice_idx].integral,
+					cfg->slice_configs[slice_idx].frac);
+		pwm_set_enabled(slice_idx, true);
+	}
+
+	return 0;
+}
+
+#define PWM_INST_RPI_SLICE_DIVIDER(idx, n)				   \
+	{								   \
+		.integral = DT_INST_PROP(idx, UTIL_CAT(divider_int_, n)), \
+		.frac = DT_INST_PROP(idx, UTIL_CAT(divider_frac_, n)),	   \
+	}
+
+#define PWM_RPI_INIT(idx)									   \
+												   \
+	PINCTRL_DT_INST_DEFINE(idx);								   \
+	static const struct pwm_rpi_config pwm_rpi_config_##idx = {				   \
+		.pwm_controller = (pwm_hw_t *)DT_INST_REG_ADDR(idx),				   \
+		.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(idx),					   \
+		.slice_configs = {								   \
+			PWM_INST_RPI_SLICE_DIVIDER(idx, 0),					   \
+			PWM_INST_RPI_SLICE_DIVIDER(idx, 1),					   \
+			PWM_INST_RPI_SLICE_DIVIDER(idx, 2),					   \
+			PWM_INST_RPI_SLICE_DIVIDER(idx, 3),					   \
+			PWM_INST_RPI_SLICE_DIVIDER(idx, 4),					   \
+			PWM_INST_RPI_SLICE_DIVIDER(idx, 5),					   \
+			PWM_INST_RPI_SLICE_DIVIDER(idx, 6),					   \
+			PWM_INST_RPI_SLICE_DIVIDER(idx, 7),					   \
+		},										   \
+		.reset = RESET_DT_SPEC_INST_GET(idx),						   \
+	};											   \
+												   \
+	DEVICE_DT_INST_DEFINE(idx, pwm_rpi_init, NULL, NULL, &pwm_rpi_config_##idx, POST_KERNEL,   \
+			      CONFIG_KERNEL_INIT_PRIORITY_DEVICE, &pwm_rpi_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(PWM_RPI_INIT);

dts/arm/rpi_pico/rp2040.dtsi

@@ -151,7 +151,7 @@
 			clocks = <&system_clk>;
 			interrupts = <4 RPI_PICO_DEFAULT_IRQ_PRIORITY>;
 			interrupt-names = "PWM_IRQ_WRAP";
-			label = "PWM_CTRL_0";
+			label = "PWM_0";
 			status = "disabled";
 			#pwm-cells = <3>;
 		};

modules/hal_rpi_pico/CMakeLists.txt

@@ -93,6 +93,9 @@ if(CONFIG_HAS_RPI_PICO)
   zephyr_include_directories_ifdef(CONFIG_PICOSDK_USE_FLASH
           ${rp2_common_dir}/hardware_flash/include)
 
+  zephyr_include_directories_ifdef(CONFIG_PICOSDK_USE_PWM
+          ${rp2_common_dir}/hardware_pwm/include)
+
   # Some flash driver functions must be executed from the RAM.
   # Originally pico-sdk places them in the RW data section, so this
   # implementation does the same.
@@ -104,4 +107,5 @@ if(CONFIG_HAS_RPI_PICO)
     PROPERTIES
     COMPILE_FLAGS $<TARGET_PROPERTY:compiler,warning_no_pointer_arithmetic>
   )
+
 endif()

modules/hal_rpi_pico/Kconfig

@@ -18,3 +18,8 @@ config PICOSDK_USE_FLASH
 	bool
 	help
 	  Use the flash driver from pico-sdk
+
+config PICOSDK_USE_PWM
+	bool
+	help
+	  Use the PWM driver from pico-sdk

soc/arm/rpi_pico/rp2/soc.c

@@ -41,7 +41,7 @@ static int rp2040_init(const struct device *arg)
 			   ~(RESETS_RESET_ADC_BITS | RESETS_RESET_RTC_BITS |
 			     RESETS_RESET_SPI0_BITS | RESETS_RESET_SPI1_BITS |
 			     RESETS_RESET_UART0_BITS | RESETS_RESET_UART1_BITS |
-			     RESETS_RESET_USBCTRL_BITS));
+			     RESETS_RESET_USBCTRL_BITS | RESETS_RESET_PWM_BITS));
 
 	clocks_init();