drivers: pwm: add a SAM0 TCC based PWM driver

This runs the Timer/Counter for Control in 'normal' PWM mode.  The
number of channels and counter width depends on the device and is
imported from DeviceTree.

Signed-off-by: Michael Hope <mlhx@google.com>

CODEOWNERS

@@ -198,6 +198,7 @@
 /drivers/pinmux/stm32/                    @idlethread
 /drivers/pinmux/*hsdk*                    @iriszzw
 /drivers/pwm/*litex*                      @mateusz-holenko @kgugala @pgielda
+/drivers/pwm/*sam0*                       @nzmichaelh
 /drivers/sensor/                          @MaureenHelm
 /drivers/sensor/ams_iAQcore/              @alexanderwachter
 /drivers/sensor/ens210/                   @alexanderwachter

drivers/pwm/CMakeLists.txt

@@ -17,6 +17,7 @@ zephyr_library_sources_ifdef(CONFIG_PWM_XEC		pwm_mchp_xec.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_LITEX		pwm_litex.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_RV32M1_TPM	pwm_rv32m1_tpm.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_MCUX_TPM	pwm_mcux_tpm.c)
+zephyr_library_sources_ifdef(CONFIG_PWM_SAM0_TCC	pwm_sam0_tcc.c)
 
 zephyr_library_sources_ifdef(CONFIG_USERSPACE   pwm_handlers.c)
 zephyr_library_sources_ifdef(CONFIG_PWM_SHELL   pwm_shell.c)

drivers/pwm/Kconfig

@@ -51,4 +51,6 @@ source "drivers/pwm/Kconfig.rv32m1_tpm"
 
 source "drivers/pwm/Kconfig.mcux_tpm"
 
+source "drivers/pwm/Kconfig.sam0"
+
 endif # PWM

drivers/pwm/Kconfig.sam0

@@ -0,0 +1,10 @@
+# Atmel SAM0 TCC as PWM configuration
+
+# Copyright (c) 2020 Google LLC
+# SPDX-License-Identifier: Apache-2.0
+
+config PWM_SAM0_TCC
+	bool "Atmel SAM0 MCU Family TCC PWM Driver"
+	depends on SOC_FAMILY_SAM0
+	help
+	  Enable PWM driver for Atmel SAM0 MCUs using the TCC timer/counter.

drivers/pwm/pwm_sam0_tcc.c

@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2020 Google LLC.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * PWM driver using the SAM0 Timer/Counter (TCC) in Normal PWM (NPWM) mode.
+ * Supports the SAMD21 and SAMD5x series.
+ */
+
+#define DT_DRV_COMPAT atmel_sam0_tcc_pwm
+
+#include <device.h>
+#include <errno.h>
+#include <drivers/pwm.h>
+#include <soc.h>
+
+/* Static configuration */
+struct pwm_sam0_config {
+	Tcc *regs;
+	uint8_t channels;
+	uint8_t counter_size;
+	uint16_t prescaler;
+	uint32_t freq;
+
+#ifdef MCLK
+	volatile uint32_t *mclk;
+	uint32_t mclk_mask;
+	uint16_t gclk_id;
+#else
+	uint32_t pm_apbcmask;
+	uint16_t gclk_clkctrl_id;
+#endif
+};
+
+#define DEV_CFG(dev) ((const struct pwm_sam0_config *const)(dev)->config_info)
+
+/* Wait for the peripheral to finish all commands */
+static void wait_synchronization(Tcc *regs)
+{
+	while (regs->SYNCBUSY.reg != 0) {
+	}
+}
+
+static int pwm_sam0_get_cycles_per_sec(struct device *dev, uint32_t ch,
+				       uint64_t *cycles)
+{
+	const struct pwm_sam0_config *const cfg = DEV_CFG(dev);
+
+	if (ch >= cfg->channels) {
+		return -EINVAL;
+	}
+	*cycles = cfg->freq;
+
+	return 0;
+}
+
+static int pwm_sam0_pin_set(struct device *dev, uint32_t ch,
+			    uint32_t period_cycles, uint32_t pulse_cycles,
+			    pwm_flags_t flags)
+{
+	const struct pwm_sam0_config *const cfg = DEV_CFG(dev);
+	Tcc *regs = cfg->regs;
+	uint32_t top = 1 << cfg->counter_size;
+	uint32_t invert_mask = 1 << ch;
+	bool invert = ((flags & PWM_POLARITY_INVERTED) != 0);
+	bool inverted = ((regs->DRVCTRL.vec.INVEN & invert_mask) != 0);
+
+	if (ch >= cfg->channels) {
+		return -EINVAL;
+	}
+	if (period_cycles >= top || pulse_cycles >= top) {
+		return -EINVAL;
+	}
+
+	/*
+	 * Update the buffered width and period.  These will be automatically
+	 * loaded on the next cycle.
+	 */
+#ifdef TCC_PERBUF_PERBUF
+	/* SAME51 naming */
+	regs->CCBUF[ch].reg = TCC_CCBUF_CCBUF(pulse_cycles);
+	regs->PERBUF.reg = TCC_PERBUF_PERBUF(period_cycles);
+#else
+	/* SAMD21 naming */
+	regs->CCB[ch].reg = TCC_CCB_CCB(pulse_cycles);
+	regs->PERB.reg = TCC_PERB_PERB(period_cycles);
+#endif
+
+	if (invert != inverted) {
+		regs->CTRLA.bit.ENABLE = 0;
+		wait_synchronization(regs);
+
+		regs->DRVCTRL.vec.INVEN ^= invert_mask;
+		regs->CTRLA.bit.ENABLE = 1;
+		wait_synchronization(regs);
+	}
+
+	return 0;
+}
+
+static int pwm_sam0_init(struct device *dev)
+{
+	const struct pwm_sam0_config *const cfg = DEV_CFG(dev);
+	Tcc *regs = cfg->regs;
+
+	/* Enable the clocks */
+#ifdef MCLK
+	GCLK->PCHCTRL[cfg->gclk_id].reg =
+		GCLK_PCHCTRL_GEN_GCLK0 | GCLK_PCHCTRL_CHEN;
+	*cfg->mclk |= cfg->mclk_mask;
+#else
+	GCLK->CLKCTRL.reg = cfg->gclk_clkctrl_id | GCLK_CLKCTRL_GEN_GCLK0 |
+			    GCLK_CLKCTRL_CLKEN;
+	PM->APBCMASK.reg |= cfg->pm_apbcmask;
+#endif
+
+	regs->CTRLA.bit.SWRST = 1;
+	wait_synchronization(regs);
+
+	regs->CTRLA.reg = cfg->prescaler;
+	regs->WAVE.reg = TCC_WAVE_WAVEGEN_NPWM;
+	regs->PER.reg = TCC_PER_PER(1);
+
+	regs->CTRLA.bit.ENABLE = 1;
+	wait_synchronization(regs);
+
+	return 0;
+}
+
+static const struct pwm_driver_api pwm_sam0_driver_api = {
+	.pin_set = pwm_sam0_pin_set,
+	.get_cycles_per_sec = pwm_sam0_get_cycles_per_sec,
+};
+
+#ifdef MCLK
+#define PWM_SAM0_INIT_CLOCKS(inst)					       \
+	.mclk = (volatile uint32_t *)MCLK_MASK_DT_INT_REG_ADDR(inst),	       \
+	.mclk_mask = BIT(DT_INST_CLOCKS_CELL_BY_NAME(inst, mclk, bit)),	       \
+	.gclk_id = DT_INST_CLOCKS_CELL_BY_NAME(inst, gclk, periph_ch)
+#else
+#define PWM_SAM0_INIT_CLOCKS(inst)					       \
+	.pm_apbcmask = BIT(DT_INST_CLOCKS_CELL_BY_NAME(inst, pm, bit)),	       \
+	.gclk_clkctrl_id = DT_INST_CLOCKS_CELL_BY_NAME(inst, gclk, clkctrl_id)
+#endif
+
+#define PWM_SAM0_INIT(inst)						       \
+	static const struct pwm_sam0_config pwm_sam0_config_##inst = {	       \
+		.regs = (Tcc *)DT_INST_REG_ADDR(inst),			       \
+		.channels = DT_INST_PROP(inst, channels),		       \
+		.counter_size = DT_INST_PROP(inst, counter_size),	       \
+		.prescaler = UTIL_CAT(TCC_CTRLA_PRESCALER_DIV,		       \
+				      DT_INST_PROP(inst, prescaler)),	       \
+		.freq = SOC_ATMEL_SAM0_GCLK0_FREQ_HZ /			       \
+			DT_INST_PROP(inst, prescaler),			       \
+		PWM_SAM0_INIT_CLOCKS(inst),				       \
+	};								       \
+									       \
+	DEVICE_AND_API_INIT(pwm_sam0_##inst, DT_INST_LABEL(inst),	       \
+			    &pwm_sam0_init, NULL, &pwm_sam0_config_##inst,     \
+			    POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,   \
+			    &pwm_sam0_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(PWM_SAM0_INIT)