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 
21 struct 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 
ir_spi_tx(struct rc_dev * dev,unsigned int * buffer,unsigned int count)34 static 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 
ir_spi_set_tx_carrier(struct rc_dev * dev,u32 carrier)83 static 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 
ir_spi_set_duty_cycle(struct rc_dev * dev,u32 duty_cycle)95 static 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 
ir_spi_probe(struct spi_device * spi)112 static 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 
155 static const struct of_device_id ir_spi_of_match[] = {
156 	{ .compatible = "ir-spi-led" },
157 	{},
158 };
159 MODULE_DEVICE_TABLE(of, ir_spi_of_match);
160 
161 static struct spi_driver ir_spi_driver = {
162 	.probe = ir_spi_probe,
163 	.driver = {
164 		.name = IR_SPI_DRIVER_NAME,
165 		.of_match_table = ir_spi_of_match,
166 	},
167 };
168 
169 module_spi_driver(ir_spi_driver);
170 
171 MODULE_AUTHOR("Andi Shyti <andi@etezian.org>");
172 MODULE_DESCRIPTION("SPI IR LED");
173 MODULE_LICENSE("GPL v2");
174