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

DEFINITIONS

1. ir_spi_tx
2. ir_spi_set_tx_carrier
3. ir_spi_set_duty_cycle
4. ir_spi_probe
5. ir_spi_remove

   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 
  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 
  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 
  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 
 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 int ir_spi_remove(struct spi_device *spi)
 156 {
 157         return 0;
 158 }
 159 
 160 static const struct of_device_id ir_spi_of_match[] = {
 161         { .compatible = "ir-spi-led" },
 162         {},
 163 };
 164 MODULE_DEVICE_TABLE(of, ir_spi_of_match);
 165 
 166 static struct spi_driver ir_spi_driver = {
 167         .probe = ir_spi_probe,
 168         .remove = ir_spi_remove,
 169         .driver = {
 170                 .name = IR_SPI_DRIVER_NAME,
 171                 .of_match_table = ir_spi_of_match,
 172         },
 173 };
 174 
 175 module_spi_driver(ir_spi_driver);
 176 
 177 MODULE_AUTHOR("Andi Shyti <andi@etezian.org>");
 178 MODULE_DESCRIPTION("SPI IR LED");
 179 MODULE_LICENSE("GPL v2");