drivers/media/rc/ir-spi.c

   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/bits.h>
   8 #include <linux/device.h>
   9 #include <linux/err.h>
  10 #include <linux/math.h>
  11 #include <linux/mod_devicetable.h>
  12 #include <linux/module.h>
  13 #include <linux/property.h>
  14 #include <linux/regulator/consumer.h>
  15 #include <linux/spi/spi.h>
  16 #include <linux/string.h>
  17 #include <linux/types.h>
  18
  19 #include <media/rc-core.h>
  20
  21 #define IR_SPI_DRIVER_NAME              "ir-spi"
  22
  23 #define IR_SPI_DEFAULT_FREQUENCY        38000
  24 #define IR_SPI_MAX_BUFSIZE               4096
  25
  26 struct ir_spi_data {
  27         u32 freq;
  28         bool negated;
  29
  30         u16 tx_buf[IR_SPI_MAX_BUFSIZE];
  31         u16 pulse;
  32         u16 space;
  33
  34         struct rc_dev *rc;
  35         struct spi_device *spi;
  36         struct regulator *regulator;
  37 };
  38
  39 static int ir_spi_tx(struct rc_dev *dev, unsigned int *buffer, unsigned int count)
  40 {
  41         int i;
  42         int ret;
  43         unsigned int len = 0;
  44         struct ir_spi_data *idata = dev->priv;
  45         struct spi_transfer xfer;
  46
  47         /* convert the pulse/space signal to raw binary signal */
  48         for (i = 0; i < count; i++) {
  49                 unsigned int periods;
  50                 int j;
  51                 u16 val;
  52
  53                 periods = DIV_ROUND_CLOSEST(buffer[i] * idata->freq, 1000000);
  54
  55                 if (len + periods >= IR_SPI_MAX_BUFSIZE)
  56                         return -EINVAL;
  57
  58                 /*
  59                  * The first value in buffer is a pulse, so that 0, 2, 4, ...
  60                  * contain a pulse duration. On the contrary, 1, 3, 5, ...
  61                  * contain a space duration.
  62                  */
  63                 val = (i % 2) ? idata->space : idata->pulse;
  64                 for (j = 0; j < periods; j++)
  65                         idata->tx_buf[len++] = val;
  66         }
  67
  68         memset(&xfer, 0, sizeof(xfer));
  69
  70         xfer.speed_hz = idata->freq * 16;
  71         xfer.len = len * sizeof(*idata->tx_buf);
  72         xfer.tx_buf = idata->tx_buf;
  73
  74         ret = regulator_enable(idata->regulator);
  75         if (ret)
  76                 return ret;
  77
  78         ret = spi_sync_transfer(idata->spi, &xfer, 1);
  79         if (ret)
  80                 dev_err(&idata->spi->dev, "unable to deliver the signal\n");
  81
  82         regulator_disable(idata->regulator);
  83
  84         return ret ? ret : count;
  85 }
  86
  87 static int ir_spi_set_tx_carrier(struct rc_dev *dev, u32 carrier)
  88 {
  89         struct ir_spi_data *idata = dev->priv;
  90
  91         if (!carrier)
  92                 return -EINVAL;
  93
  94         idata->freq = carrier;
  95
  96         return 0;
  97 }
  98
  99 static int ir_spi_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
 100 {
 101         struct ir_spi_data *idata = dev->priv;
 102         int bits = (duty_cycle * 15) / 100;
 103
 104         idata->pulse = GENMASK(bits, 0);
 105
 106         if (idata->negated) {
 107                 idata->pulse = ~idata->pulse;
 108                 idata->space = 0xffff;
 109         } else {
 110                 idata->space = 0;
 111         }
 112
 113         return 0;
 114 }
 115
 116 static int ir_spi_probe(struct spi_device *spi)
 117 {
 118         struct device *dev = &spi->dev;
 119         int ret;
 120         u8 dc;
 121         struct ir_spi_data *idata;
 122
 123         idata = devm_kzalloc(dev, sizeof(*idata), GFP_KERNEL);
 124         if (!idata)
 125                 return -ENOMEM;
 126
 127         idata->regulator = devm_regulator_get(dev, "irda_regulator");
 128         if (IS_ERR(idata->regulator))
 129                 return PTR_ERR(idata->regulator);
 130
 131         idata->rc = devm_rc_allocate_device(&spi->dev, RC_DRIVER_IR_RAW_TX);
 132         if (!idata->rc)
 133                 return -ENOMEM;
 134
 135         idata->rc->tx_ir           = ir_spi_tx;
 136         idata->rc->s_tx_carrier    = ir_spi_set_tx_carrier;
 137         idata->rc->s_tx_duty_cycle = ir_spi_set_duty_cycle;
 138         idata->rc->device_name     = "IR SPI";
 139         idata->rc->driver_name     = IR_SPI_DRIVER_NAME;
 140         idata->rc->priv            = idata;
 141         idata->spi                 = spi;
 142
 143         idata->negated = device_property_read_bool(dev, "led-active-low");
 144         ret = device_property_read_u8(dev, "duty-cycle", &dc);
 145         if (ret)
 146                 dc = 50;
 147
 148         /*
 149          * ir_spi_set_duty_cycle() cannot fail, it returns int
 150          * to be compatible with the rc->s_tx_duty_cycle function.
 151          */
 152         ir_spi_set_duty_cycle(idata->rc, dc);
 153
 154         idata->freq = IR_SPI_DEFAULT_FREQUENCY;
 155
 156         return devm_rc_register_device(dev, idata->rc);
 157 }
 158
 159 static const struct of_device_id ir_spi_of_match[] = {
 160         { .compatible = "ir-spi-led" },
 161         {}
 162 };
 163 MODULE_DEVICE_TABLE(of, ir_spi_of_match);
 164
 165 static const struct spi_device_id ir_spi_ids[] = {
 166         { "ir-spi-led" },
 167         {}
 168 };
 169 MODULE_DEVICE_TABLE(spi, ir_spi_ids);
 170
 171 static struct spi_driver ir_spi_driver = {
 172         .probe = ir_spi_probe,
 173         .id_table = ir_spi_ids,
 174         .driver = {
 175                 .name = IR_SPI_DRIVER_NAME,
 176                 .of_match_table = ir_spi_of_match,
 177         },
 178 };
 179 module_spi_driver(ir_spi_driver);
 180
 181 MODULE_AUTHOR("Andi Shyti <andi@etezian.org>");
 182 MODULE_DESCRIPTION("SPI IR LED");
 183 MODULE_LICENSE("GPL v2");