linux_kernel/drivers/media/rc/ir-spi.c

/*
 * Copyright (c) 2016 Samsung Electronics Co., Ltd.
 * Author: Andi Shyti <andi.shyti@samsung.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * SPI driven IR LED device driver
 */

#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of_gpio.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#include <media/rc-core.h>

#define IR_SPI_DRIVER_NAME		"ir-spi"

/* pulse value for different duty cycles */
#define IR_SPI_PULSE_DC_50		0xff00
#define IR_SPI_PULSE_DC_60		0xfc00
#define IR_SPI_PULSE_DC_70		0xf800
#define IR_SPI_PULSE_DC_75		0xf000
#define IR_SPI_PULSE_DC_80		0xc000
#define IR_SPI_PULSE_DC_90		0x8000

#define IR_SPI_DEFAULT_FREQUENCY	38000
#define IR_SPI_BIT_PER_WORD		    8
#define IR_SPI_MAX_BUFSIZE		 4096

struct ir_spi_data {
	u32 freq;
	u8 duty_cycle;
	bool negated;

	u16 tx_buf[IR_SPI_MAX_BUFSIZE];
	u16 pulse;
	u16 space;

	struct rc_dev *rc;
	struct spi_device *spi;
	struct regulator *regulator;
};

static int ir_spi_tx(struct rc_dev *dev,
		     unsigned int *buffer, unsigned int count)
{
	int i;
	int ret;
	unsigned int len = 0;
	struct ir_spi_data *idata = dev->priv;
	struct spi_transfer xfer;

	/* convert the pulse/space signal to raw binary signal */
	for (i = 0; i < count; i++) {
		int j;
		u16 val = ((i + 1) % 2) ? idata->pulse : idata->space;

		if (len + buffer[i] >= IR_SPI_MAX_BUFSIZE)
			return -EINVAL;

		/*
		 * the first value in buffer is a pulse, so that 0, 2, 4, ...
		 * contain a pulse duration. On the contrary, 1, 3, 5, ...
		 * contain a space duration.
		 */
		val = (i % 2) ? idata->space : idata->pulse;
		for (j = 0; j < buffer[i]; j++)
			idata->tx_buf[len++] = val;
	}

	memset(&xfer, 0, sizeof(xfer));

	xfer.speed_hz = idata->freq;
	xfer.len = len * sizeof(*idata->tx_buf);
	xfer.tx_buf = idata->tx_buf;

	ret = regulator_enable(idata->regulator);
	if (ret)
		return ret;

	ret = spi_sync_transfer(idata->spi, &xfer, 1);
	if (ret)
		dev_err(&idata->spi->dev, "unable to deliver the signal\n");

	regulator_disable(idata->regulator);

	return ret ? ret : count;
}

static int ir_spi_set_tx_carrier(struct rc_dev *dev, u32 carrier)
{
	struct ir_spi_data *idata = dev->priv;

	if (!carrier)
		return -EINVAL;

	idata->freq = carrier;

	return 0;
}

static int ir_spi_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
{
	struct ir_spi_data *idata = dev->priv;

	if (duty_cycle >= 90)
		idata->pulse = IR_SPI_PULSE_DC_90;
	else if (duty_cycle >= 80)
		idata->pulse = IR_SPI_PULSE_DC_80;
	else if (duty_cycle >= 75)
		idata->pulse = IR_SPI_PULSE_DC_75;
	else if (duty_cycle >= 70)
		idata->pulse = IR_SPI_PULSE_DC_70;
	else if (duty_cycle >= 60)
		idata->pulse = IR_SPI_PULSE_DC_60;
	else
		idata->pulse = IR_SPI_PULSE_DC_50;

	if (idata->negated) {
		idata->pulse = ~idata->pulse;
		idata->space = 0xffff;
	} else {
		idata->space = 0;
	}

	return 0;
}

static int ir_spi_probe(struct spi_device *spi)
{
	int ret;
	u8 dc;
	struct ir_spi_data *idata;

	idata = devm_kzalloc(&spi->dev, sizeof(*idata), GFP_KERNEL);
	if (!idata)
		return -ENOMEM;

	idata->regulator = devm_regulator_get(&spi->dev, "irda_regulator");
	if (IS_ERR(idata->regulator))
		return PTR_ERR(idata->regulator);

	idata->rc = devm_rc_allocate_device(&spi->dev, RC_DRIVER_IR_RAW_TX);
	if (!idata->rc)
		return -ENOMEM;

	idata->rc->tx_ir           = ir_spi_tx;
	idata->rc->s_tx_carrier    = ir_spi_set_tx_carrier;
	idata->rc->s_tx_duty_cycle = ir_spi_set_duty_cycle;
	idata->rc->driver_name     = IR_SPI_DRIVER_NAME;
	idata->rc->priv            = idata;
	idata->spi                 = spi;

	idata->negated = of_property_read_bool(spi->dev.of_node,
							"led-active-low");
	ret = of_property_read_u8(spi->dev.of_node, "duty-cycle", &dc);
	if (ret)
		dc = 50;

	/* ir_spi_set_duty_cycle cannot fail,
	 * it returns int to be compatible with the
	 * rc->s_tx_duty_cycle function
	 */
	ir_spi_set_duty_cycle(idata->rc, dc);

	idata->freq = IR_SPI_DEFAULT_FREQUENCY;

	return devm_rc_register_device(&spi->dev, idata->rc);
}

static int ir_spi_remove(struct spi_device *spi)
{
	return 0;
}

static const struct of_device_id ir_spi_of_match[] = {
	{ .compatible = "ir-spi-led" },
	{},
};

static struct spi_driver ir_spi_driver = {
	.probe = ir_spi_probe,
	.remove = ir_spi_remove,
	.driver = {
		.name = IR_SPI_DRIVER_NAME,
		.of_match_table = ir_spi_of_match,
	},
};

module_spi_driver(ir_spi_driver);

MODULE_AUTHOR("Andi Shyti <andi.shyti@samsung.com>");
MODULE_DESCRIPTION("SPI IR LED");
MODULE_LICENSE("GPL v2");