spi: offload-trigger: add PWM trigger driver (ebb398ae) · Commits · git / linux-net

MAINTAINERS

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		@@ -22297,6 +22297,7 @@ F: include/linux/mtd/spi-nor.h

		SPI OFFLOAD
		R: David Lechner <dlechner@baylibre.com>
		F: drivers/spi/spi-offload-trigger-pwm.c
		F: drivers/spi/spi-offload.c
		F: include/linux/spi/spi-offload.h
		K: spi_offload

drivers/spi/Kconfig

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		@@ -1320,4 +1320,16 @@ endif # SPI_SLAVE
		config SPI_DYNAMIC
		def_bool ACPI \|\| OF_DYNAMIC \|\| SPI_SLAVE

		if SPI_OFFLOAD

		comment "SPI Offload triggers"

		config SPI_OFFLOAD_TRIGGER_PWM
		tristate "SPI offload trigger using PWM"
		depends on PWM
		help
		Generic SPI offload trigger implemented using PWM output.

		endif # SPI_OFFLOAD

		endif # SPI

drivers/spi/Makefile

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		@@ -164,3 +164,6 @@ obj-$(CONFIG_SPI_AMD) += spi-amd.o
		# SPI slave protocol handlers
		obj-$(CONFIG_SPI_SLAVE_TIME) += spi-slave-time.o
		obj-$(CONFIG_SPI_SLAVE_SYSTEM_CONTROL) += spi-slave-system-control.o

		# SPI offload triggers
		obj-$(CONFIG_SPI_OFFLOAD_TRIGGER_PWM) += spi-offload-trigger-pwm.o

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

0 → 100644

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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/platform_device.h>
		#include <linux/pwm.h>
		#include <linux/mod_devicetable.h>
		#include <linux/spi/offload/provider.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");