drivers/spi/spi-offload-trigger-pwm.c

Source file repositories/reference/linux-study-clean/drivers/spi/spi-offload-trigger-pwm.c

File Facts

System
Linux kernel
Corpus path
drivers/spi/spi-offload-trigger-pwm.c
Extension
.c
Size
4846 bytes
Lines
173
Domain
Driver Families
Bucket
drivers/spi
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct spi_offload_trigger_pwm_state {
	struct device *dev;
	struct pwm_device *pwm;
};

static bool spi_offload_trigger_pwm_match(struct spi_offload_trigger *trigger,
					  enum spi_offload_trigger_type type,
					  u64 *args, u32 nargs)
{
	if (nargs)
		return false;

	return type == SPI_OFFLOAD_TRIGGER_PERIODIC;
}

static int spi_offload_trigger_pwm_validate(struct spi_offload_trigger *trigger,
					    struct spi_offload_trigger_config *config)
{
	struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
	struct spi_offload_trigger_periodic *periodic = &config->periodic;
	struct pwm_waveform wf = { };
	int ret;

	if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
		return -EINVAL;

	if (!periodic->frequency_hz)
		return -EINVAL;

	wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
	/* REVISIT: 50% duty-cycle for now - may add config parameter later */
	wf.duty_length_ns = wf.period_length_ns / 2;
	wf.duty_offset_ns = periodic->offset_ns;

	ret = pwm_round_waveform_might_sleep(st->pwm, &wf);
	if (ret < 0)
		return ret;

	periodic->frequency_hz = DIV_ROUND_UP_ULL(NSEC_PER_SEC, wf.period_length_ns);
	periodic->offset_ns = wf.duty_offset_ns;

	return 0;
}

static int spi_offload_trigger_pwm_enable(struct spi_offload_trigger *trigger,
					  struct spi_offload_trigger_config *config)
{
	struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
	struct spi_offload_trigger_periodic *periodic = &config->periodic;
	struct pwm_waveform wf = { };

	if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
		return -EINVAL;

	if (!periodic->frequency_hz)
		return -EINVAL;

	wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
	/* REVISIT: 50% duty-cycle for now - may add config parameter later */
	wf.duty_length_ns = wf.period_length_ns / 2;
	wf.duty_offset_ns = periodic->offset_ns;

	return pwm_set_waveform_might_sleep(st->pwm, &wf, false);
}

static void spi_offload_trigger_pwm_disable(struct spi_offload_trigger *trigger)
{
	struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
	struct pwm_waveform wf;
	int ret;

	ret = pwm_get_waveform_might_sleep(st->pwm, &wf);
	if (ret < 0) {
		dev_err(st->dev, "failed to get waveform: %d\n", ret);
		return;
	}

	wf.duty_length_ns = 0;

	ret = pwm_set_waveform_might_sleep(st->pwm, &wf, false);
	if (ret < 0)
		dev_err(st->dev, "failed to disable PWM: %d\n", ret);
}

static const struct spi_offload_trigger_ops spi_offload_trigger_pwm_ops = {
	.match = spi_offload_trigger_pwm_match,
	.validate = spi_offload_trigger_pwm_validate,
	.enable = spi_offload_trigger_pwm_enable,
	.disable = spi_offload_trigger_pwm_disable,
};

Annotation

Implementation Notes