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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2024 Analog Devices Inc.
* Copyright (C) 2024 BayLibre, SAS
*
* Generic PWM trigger for SPI offload.
*/
#include <linux/device.h>
#include <linux/err.h>
#include <linux/math.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/pwm.h>
#include <linux/spi/offload/provider.h>
#include <linux/spi/offload/types.h>
#include <linux/time.h>
#include <linux/types.h>
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;
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);
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;
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,
};
static void spi_offload_trigger_pwm_release(void *data)
{
pwm_disable(data);
}
static int spi_offload_trigger_pwm_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct spi_offload_trigger_info info = {
.fwnode = dev_fwnode(dev),
.ops = &spi_offload_trigger_pwm_ops,
};
struct spi_offload_trigger_pwm_state *st;
struct pwm_state state;
int ret;
st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
if (!st)
return -ENOMEM;
info.priv = st;
st->dev = dev;
st->pwm = devm_pwm_get(dev, NULL);
if (IS_ERR(st->pwm))
return dev_err_probe(dev, PTR_ERR(st->pwm), "failed to get PWM\n");
/* init with duty_cycle = 0, output enabled to ensure trigger off */
pwm_init_state(st->pwm, &state);
state.enabled = true;
ret = pwm_apply_might_sleep(st->pwm, &state);
if (ret < 0)
return dev_err_probe(dev, ret, "failed to apply PWM state\n");
ret = devm_add_action_or_reset(dev, spi_offload_trigger_pwm_release, st->pwm);
if (ret)
return ret;
return devm_spi_offload_trigger_register(dev, &info);
}
static const struct of_device_id spi_offload_trigger_pwm_of_match_table[] = {
{ .compatible = "pwm-trigger" },
{ }
};
MODULE_DEVICE_TABLE(of, spi_offload_trigger_pwm_of_match_table);
static struct platform_driver spi_offload_trigger_pwm_driver = {
.driver = {
.name = "pwm-trigger",
.of_match_table = spi_offload_trigger_pwm_of_match_table,
},
.probe = spi_offload_trigger_pwm_probe,
};
module_platform_driver(spi_offload_trigger_pwm_driver);
MODULE_AUTHOR("David Lechner <dlechner@baylibre.com>");
MODULE_DESCRIPTION("Generic PWM trigger");
MODULE_LICENSE("GPL");
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