1// SPDX-License-Identifier: GPL-2.0
  2// SPI driven IR LED device driver
  3//
  4// Copyright (c) 2016 Samsung Electronics Co., Ltd.
  5// Copyright (c) Andi Shyti <andi@etezian.org>
  6
  7#include <linux/delay.h>
  8#include <linux/fs.h>
  9#include <linux/module.h>
 10#include <linux/mutex.h>
 11#include <linux/of_gpio.h>
 12#include <linux/regulator/consumer.h>
 13#include <linux/spi/spi.h>
 14#include <media/rc-core.h>
 15
 16#define IR_SPI_DRIVER_NAME		"ir-spi"
 17
 18#define IR_SPI_DEFAULT_FREQUENCY	38000
 19#define IR_SPI_MAX_BUFSIZE		 4096
 20
 21struct ir_spi_data {
 22	u32 freq;
 23	bool negated;
 24
 25	u16 tx_buf[IR_SPI_MAX_BUFSIZE];
 26	u16 pulse;
 27	u16 space;
 28
 29	struct rc_dev *rc;
 30	struct spi_device *spi;
 31	struct regulator *regulator;
 32};
 33
 34static int ir_spi_tx(struct rc_dev *dev,
 35		     unsigned int *buffer, unsigned int count)
 36{
 37	int i;
 38	int ret;
 39	unsigned int len = 0;
 40	struct ir_spi_data *idata = dev->priv;
 41	struct spi_transfer xfer;
 42
 43	/* convert the pulse/space signal to raw binary signal */
 44	for (i = 0; i < count; i++) {
 45		unsigned int periods;
 46		int j;
 47		u16 val;
 48
 49		periods = DIV_ROUND_CLOSEST(buffer[i] * idata->freq, 1000000);
 50
 51		if (len + periods >= IR_SPI_MAX_BUFSIZE)
 52			return -EINVAL;
 53
 54		/*
 55		 * the first value in buffer is a pulse, so that 0, 2, 4, ...
 56		 * contain a pulse duration. On the contrary, 1, 3, 5, ...
 57		 * contain a space duration.
 58		 */
 59		val = (i % 2) ? idata->space : idata->pulse;
 60		for (j = 0; j < periods; j++)
 61			idata->tx_buf[len++] = val;
 62	}
 63
 64	memset(&xfer, 0, sizeof(xfer));
 65
 66	xfer.speed_hz = idata->freq * 16;
 67	xfer.len = len * sizeof(*idata->tx_buf);
 68	xfer.tx_buf = idata->tx_buf;
 69
 70	ret = regulator_enable(idata->regulator);
 71	if (ret)
 72		return ret;
 73
 74	ret = spi_sync_transfer(idata->spi, &xfer, 1);
 75	if (ret)
 76		dev_err(&idata->spi->dev, "unable to deliver the signal\n");
 77
 78	regulator_disable(idata->regulator);
 79
 80	return ret ? ret : count;
 81}
 82
 83static int ir_spi_set_tx_carrier(struct rc_dev *dev, u32 carrier)
 84{
 85	struct ir_spi_data *idata = dev->priv;
 86
 87	if (!carrier)
 88		return -EINVAL;
 89
 90	idata->freq = carrier;
 91
 92	return 0;
 93}
 94
 95static int ir_spi_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
 96{
 97	struct ir_spi_data *idata = dev->priv;
 98	int bits = (duty_cycle * 15) / 100;
 99
100	idata->pulse = GENMASK(bits, 0);
101
102	if (idata->negated) {
103		idata->pulse = ~idata->pulse;
104		idata->space = 0xffff;
105	} else {
106		idata->space = 0;
107	}
108
109	return 0;
110}
111
112static int ir_spi_probe(struct spi_device *spi)
113{
114	int ret;
115	u8 dc;
116	struct ir_spi_data *idata;
117
118	idata = devm_kzalloc(&spi->dev, sizeof(*idata), GFP_KERNEL);
119	if (!idata)
120		return -ENOMEM;
121
122	idata->regulator = devm_regulator_get(&spi->dev, "irda_regulator");
123	if (IS_ERR(idata->regulator))
124		return PTR_ERR(idata->regulator);
125
126	idata->rc = devm_rc_allocate_device(&spi->dev, RC_DRIVER_IR_RAW_TX);
127	if (!idata->rc)
128		return -ENOMEM;
129
130	idata->rc->tx_ir           = ir_spi_tx;
131	idata->rc->s_tx_carrier    = ir_spi_set_tx_carrier;
132	idata->rc->s_tx_duty_cycle = ir_spi_set_duty_cycle;
133	idata->rc->device_name	   = "IR SPI";
134	idata->rc->driver_name     = IR_SPI_DRIVER_NAME;
135	idata->rc->priv            = idata;
136	idata->spi                 = spi;
137
138	idata->negated = of_property_read_bool(spi->dev.of_node,
139							"led-active-low");
140	ret = of_property_read_u8(spi->dev.of_node, "duty-cycle", &dc);
141	if (ret)
142		dc = 50;
143
144	/* ir_spi_set_duty_cycle cannot fail,
145	 * it returns int to be compatible with the
146	 * rc->s_tx_duty_cycle function
147	 */
148	ir_spi_set_duty_cycle(idata->rc, dc);
149
150	idata->freq = IR_SPI_DEFAULT_FREQUENCY;
151
152	return devm_rc_register_device(&spi->dev, idata->rc);
153}
154
155static const struct of_device_id ir_spi_of_match[] = {
156	{ .compatible = "ir-spi-led" },
157	{},
158};
159MODULE_DEVICE_TABLE(of, ir_spi_of_match);
160
161static const struct spi_device_id ir_spi_ids[] = {
162	{ "ir-spi-led" },
163	{},
164};
165MODULE_DEVICE_TABLE(spi, ir_spi_ids);
166
167static struct spi_driver ir_spi_driver = {
168	.probe = ir_spi_probe,
169	.id_table = ir_spi_ids,
170	.driver = {
171		.name = IR_SPI_DRIVER_NAME,
172		.of_match_table = ir_spi_of_match,
173	},
174};
175
176module_spi_driver(ir_spi_driver);
177
178MODULE_AUTHOR("Andi Shyti <andi@etezian.org>");
179MODULE_DESCRIPTION("SPI IR LED");
180MODULE_LICENSE("GPL v2");