pwm: pwm_seesaw: new driver

Add new pwm driver for the Adafruit Seesaw

Signed-off-by: Titouan Christophe <[email protected]>

Author: titouanc

drivers/pwm/CMakeLists.txt

@@ -52,6 +52,7 @@ 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_PWM_SEESAW  pwm_seesaw.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

@@ -126,4 +126,6 @@ source "drivers/pwm/Kconfig.rts5912"
 
 source "drivers/pwm/Kconfig.neorv32"
 
+source "drivers/pwm/Kconfig.seesaw"
+
 endif # PWM

drivers/pwm/Kconfig.seesaw

@@ -0,0 +1,10 @@
+# Copyright 2025 Titouan Chrisotphe
+# SPDX-License-Identifier: Apache-2.0
+
+config PWM_SEESAW
+	bool "Adafruit Seesaw PWM over I2C"
+	default y
+	depends on MFD_SEESAW
+	depends on DT_HAS_ADAFRUIT_SEESAW_PWM_ENABLED
+	help
+	  Enable support for Adafruit Seesaw pwm

drivers/pwm/pwm_seesaw.c

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2025 Titouan Christophe
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT adafruit_seesaw_pwm
+
+#include <zephyr/drivers/mfd/mfd_seesaw.h>
+#include <zephyr/drivers/pwm.h>
+
+/* See https://learn.adafruit.com/adafruit-seesaw-atsamd09-breakout/pwm */
+
+#define FIXED_CYCLES 0xffff
+
+enum seesaw_mod_pwm {
+	PWM_VAL  = 0x01,
+	PWM_FREQ = 0x02,
+};
+
+struct seesaw_pwm_config {
+	const struct device *seesaw;
+};
+
+static int seesaw_pwm_get_cycles_per_sec(const struct device *dev,
+					 uint32_t channel, uint64_t *cycles)
+{
+	*cycles = FIXED_CYCLES;
+	return 0;
+}
+
+static inline int seesaw_pwm_write(const struct device *seesaw_dev, uint8_t reg,
+				   uint8_t channel, uint16_t value)
+{
+	const uint8_t buf[3] = {channel, (value >> 8), (value & 0xff)};
+
+	return seesaw_write(seesaw_dev, SEESAW_MOD_PWM, reg, buf, 3);
+}
+
+static int seesaw_pwm_set_cycles(const struct device *dev, uint32_t channel,
+				 uint32_t period, uint32_t pulse,
+				 pwm_flags_t flags)
+{
+	int ret;
+	const struct seesaw_pwm_config *const config = dev->config;
+	uint16_t freq = 0;
+	uint16_t val = 0;
+
+	if (period > 0) {
+		freq = FIXED_CYCLES / period;
+		val = 0xffff * pulse / period;
+	}
+
+	ret = seesaw_pwm_write(config->seesaw, PWM_VAL, channel, val);
+	if (ret) {
+		return ret;
+	}
+
+	return seesaw_pwm_write(config->seesaw, PWM_FREQ, channel, freq);
+}
+
+static DEVICE_API(pwm, seesaw_pwm_api) = {
+	.set_cycles = seesaw_pwm_set_cycles,
+	.get_cycles_per_sec = seesaw_pwm_get_cycles_per_sec,
+};
+
+static int seesaw_pwm_init(const struct device *dev)
+{
+	const struct seesaw_pwm_config *const config = dev->config;
+
+	return seesaw_claim_module(config->seesaw, SEESAW_MOD_PWM, dev);
+}
+
+#define SEESAW_PWM_INIT(inst)							 \
+	static const struct seesaw_pwm_config config_##inst = {			 \
+		.seesaw = DEVICE_DT_GET(DT_INST_PARENT(inst)),			 \
+	};									 \
+	DEVICE_DT_INST_DEFINE(inst, seesaw_pwm_init, NULL, NULL, &config_##inst, \
+			      POST_KERNEL, CONFIG_MFD_INIT_PRIORITY, &seesaw_pwm_api);
+
+DT_INST_FOREACH_STATUS_OKAY(SEESAW_PWM_INIT)

dts/bindings/pwm/adafruit,seesaw-pwm.yaml

@@ -0,0 +1,22 @@
+# Copyright (c) 2025 Titouan Christophe
+# SPDX-License-Identifier: Apache-2.0
+
+description: Adafruit Seesaw PWM
+
+compatible: "adafruit,seesaw-pwm"
+
+include: [pwm-controller.yaml]
+
+properties:
+  "#pwm-cells":
+    const: 3
+    description: |
+      Number of items to expect in a PWM
+      - channel
+      - period
+      - flags
+
+pwm-cells:
+  - channel
+  - period
+  - flags