drivers/pwm/pwm_sam.c

/*
 * Copyright (c) 2019 Aurelien Jarno
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <device.h>
#include <errno.h>
#include <pwm.h>
#include <soc.h>

#define LOG_LEVEL CONFIG_PWM_LOG_LEVEL
#include <logging/log.h>
LOG_MODULE_REGISTER(pwm_sam);

struct sam_pwm_config {
	Pwm *regs;
	u32_t id;
	u8_t prescaler;
	u8_t divider;
};

#define DEV_CFG(dev) \
	((const struct sam_pwm_config * const)(dev)->config->config_info)

static int sam_pwm_get_cycles_per_sec(struct device *dev, u32_t pwm,
				      u64_t *cycles)
{
	u8_t prescaler = DEV_CFG(dev)->prescaler;
	u8_t divider = DEV_CFG(dev)->divider;

	*cycles = SOC_ATMEL_SAM_MCK_FREQ_HZ /
		  ((1 << prescaler) * divider);

	return 0;
}

static int sam_pwm_pin_set(struct device *dev, u32_t ch,
			   u32_t period_cycles, u32_t pulse_cycles)
{
	Pwm *const pwm = DEV_CFG(dev)->regs;

	if (ch >= PWMCHNUM_NUMBER) {
		return -EINVAL;
	}

	if (period_cycles == 0U || pulse_cycles > period_cycles) {
		return -EINVAL;
	}

	if (period_cycles > 0xffff) {
		return -ENOTSUP;
	}

	/* Select clock A */
	pwm->PWM_CH_NUM[ch].PWM_CMR = PWM_CMR_CPRE_CLKA_Val;

	/* Update period and pulse using the update registers, so that the
	 * change is triggered at the next PWM period.
	 */
	pwm->PWM_CH_NUM[ch].PWM_CPRDUPD = period_cycles;
	pwm->PWM_CH_NUM[ch].PWM_CDTYUPD = pulse_cycles;

	/* Enable the output */
	pwm->PWM_ENA = 1 << ch;

	return 0;
}

static int sam_pwm_init(struct device *dev)
{
	Pwm *const pwm = DEV_CFG(dev)->regs;
	u32_t id = DEV_CFG(dev)->id;
	u8_t prescaler = DEV_CFG(dev)->prescaler;
	u8_t divider = DEV_CFG(dev)->divider;

	/* FIXME: way to validate prescaler & divider */

	/* Enable the PWM peripheral */
	soc_pmc_peripheral_enable(id);

	/* Configure the clock A that will be used by all 4 channels */
	pwm->PWM_CLK = PWM_CLK_PREA(prescaler) | PWM_CLK_DIVA(divider);

	return 0;
}

static const struct pwm_driver_api sam_pwm_driver_api = {
	.pin_set = sam_pwm_pin_set,
	.get_cycles_per_sec = sam_pwm_get_cycles_per_sec,
};

#ifdef DT_ATMEL_SAM_PWM_0
static const struct sam_pwm_config sam_pwm_config_0 = {
	.regs = (Pwm *)DT_ATMEL_SAM_PWM_0_BASE_ADDRESS,
	.id = DT_ATMEL_SAM_PWM_0_PERIPHERAL_ID,
	.prescaler = DT_ATMEL_SAM_PWM_0_PRESCALER,
	.divider = DT_ATMEL_SAM_PWM_0_DIVIDER,
};

DEVICE_AND_API_INIT(sam_pwm_0, DT_ATMEL_SAM_PWM_0_LABEL, &sam_pwm_init,
		    NULL, &sam_pwm_config_0,
		    POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
		    &sam_pwm_driver_api);
#endif /* DT_ATMEL_SAM_PWM_0 */

#ifdef DT_ATMEL_SAM_PWM_1
static const struct sam_pwm_config sam_pwm_config_1 = {
	.regs = (Pwm *)DT_ATMEL_SAM_PWM_1_BASE_ADDRESS,
	.id = DT_ATMEL_SAM_PWM_1_PERIPHERAL_ID,
	.prescaler = DT_ATMEL_SAM_PWM_1_PRESCALER,
	.divider = DT_ATMEL_SAM_PWM_1_DIVIDER,
};

DEVICE_AND_API_INIT(sam_pwm_1, DT_ATMEL_SAM_PWM_1_LABEL, &sam_pwm_init,
		    NULL, &sam_pwm_config_1,
		    POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
		    &sam_pwm_driver_api);
#endif /* DT_ATMEL_SAM_PWM_1 */