drivers/media/rc/pwm-ir-tx.c

   1 /*
   2  * Copyright (C) 2017 Sean Young <sean@mess.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/pwm.h>
  17 #include <linux/delay.h>
  18 #include <linux/slab.h>
  19 #include <linux/of.h>
  20 #include <linux/platform_device.h>
  21 #include <media/rc-core.h>
  22
  23 #define DRIVER_NAME     "pwm-ir-tx"
  24 #define DEVICE_NAME     "PWM IR Transmitter"
  25
  26 struct pwm_ir {
  27         struct pwm_device *pwm;
  28         unsigned int carrier;
  29         unsigned int duty_cycle;
  30 };
  31
  32 static const struct of_device_id pwm_ir_of_match[] = {
  33         { .compatible = "pwm-ir-tx", },
  34         { },
  35 };
  36 MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
  37
  38 static int pwm_ir_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
  39 {
  40         struct pwm_ir *pwm_ir = dev->priv;
  41
  42         pwm_ir->duty_cycle = duty_cycle;
  43
  44         return 0;
  45 }
  46
  47 static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier)
  48 {
  49         struct pwm_ir *pwm_ir = dev->priv;
  50
  51         if (!carrier)
  52                 return -EINVAL;
  53
  54         pwm_ir->carrier = carrier;
  55
  56         return 0;
  57 }
  58
  59 static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
  60                      unsigned int count)
  61 {
  62         struct pwm_ir *pwm_ir = dev->priv;
  63         struct pwm_device *pwm = pwm_ir->pwm;
  64         int i, duty, period;
  65         ktime_t edge;
  66         long delta;
  67
  68         period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
  69         duty = DIV_ROUND_CLOSEST(pwm_ir->duty_cycle * period, 100);
  70
  71         pwm_config(pwm, duty, period);
  72
  73         edge = ktime_get();
  74
  75         for (i = 0; i < count; i++) {
  76                 if (i % 2) // space
  77                         pwm_disable(pwm);
  78                 else
  79                         pwm_enable(pwm);
  80
  81                 edge = ktime_add_us(edge, txbuf[i]);
  82                 delta = ktime_us_delta(edge, ktime_get());
  83                 if (delta > 0)
  84                         usleep_range(delta, delta + 10);
  85         }
  86
  87         pwm_disable(pwm);
  88
  89         return count;
  90 }
  91
  92 static int pwm_ir_probe(struct platform_device *pdev)
  93 {
  94         struct pwm_ir *pwm_ir;
  95         struct rc_dev *rcdev;
  96         int rc;
  97
  98         pwm_ir = devm_kmalloc(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL);
  99         if (!pwm_ir)
 100                 return -ENOMEM;
 101
 102         pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL);
 103         if (IS_ERR(pwm_ir->pwm))
 104                 return PTR_ERR(pwm_ir->pwm);
 105
 106         pwm_ir->carrier = 38000;
 107         pwm_ir->duty_cycle = 50;
 108
 109         rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
 110         if (!rcdev)
 111                 return -ENOMEM;
 112
 113         rcdev->priv = pwm_ir;
 114         rcdev->driver_name = DRIVER_NAME;
 115         rcdev->device_name = DEVICE_NAME;
 116         rcdev->tx_ir = pwm_ir_tx;
 117         rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
 118         rcdev->s_tx_carrier = pwm_ir_set_carrier;
 119
 120         rc = devm_rc_register_device(&pdev->dev, rcdev);
 121         if (rc < 0)
 122                 dev_err(&pdev->dev, "failed to register rc device\n");
 123
 124         return rc;
 125 }
 126
 127 static struct platform_driver pwm_ir_driver = {
 128         .probe = pwm_ir_probe,
 129         .driver = {
 130                 .name   = DRIVER_NAME,
 131                 .of_match_table = of_match_ptr(pwm_ir_of_match),
 132         },
 133 };
 134 module_platform_driver(pwm_ir_driver);
 135
 136 MODULE_DESCRIPTION("PWM IR Transmitter");
 137 MODULE_AUTHOR("Sean Young <sean@mess.org>");
 138 MODULE_LICENSE("GPL");