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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2017 Sean Young <sean@mess.org>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/pwm.h>
   9 #include <linux/delay.h>
  10 #include <linux/slab.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13 #include <media/rc-core.h>
  14
  15 #define DRIVER_NAME     "pwm-ir-tx"
  16 #define DEVICE_NAME     "PWM IR Transmitter"
  17
  18 struct pwm_ir {
  19         struct pwm_device *pwm;
  20         unsigned int carrier;
  21         unsigned int duty_cycle;
  22 };
  23
  24 static const struct of_device_id pwm_ir_of_match[] = {
  25         { .compatible = "pwm-ir-tx", },
  26         { },
  27 };
  28 MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
  29
  30 static int pwm_ir_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
  31 {
  32         struct pwm_ir *pwm_ir = dev->priv;
  33
  34         pwm_ir->duty_cycle = duty_cycle;
  35
  36         return 0;
  37 }
  38
  39 static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier)
  40 {
  41         struct pwm_ir *pwm_ir = dev->priv;
  42
  43         if (!carrier)
  44                 return -EINVAL;
  45
  46         pwm_ir->carrier = carrier;
  47
  48         return 0;
  49 }
  50
  51 static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
  52                      unsigned int count)
  53 {
  54         struct pwm_ir *pwm_ir = dev->priv;
  55         struct pwm_device *pwm = pwm_ir->pwm;
  56         int i, duty, period;
  57         ktime_t edge;
  58         long delta;
  59
  60         period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
  61         duty = DIV_ROUND_CLOSEST(pwm_ir->duty_cycle * period, 100);
  62
  63         pwm_config(pwm, duty, period);
  64
  65         edge = ktime_get();
  66
  67         for (i = 0; i < count; i++) {
  68                 if (i % 2) // space
  69                         pwm_disable(pwm);
  70                 else
  71                         pwm_enable(pwm);
  72
  73                 edge = ktime_add_us(edge, txbuf[i]);
  74                 delta = ktime_us_delta(edge, ktime_get());
  75                 if (delta > 0)
  76                         usleep_range(delta, delta + 10);
  77         }
  78
  79         pwm_disable(pwm);
  80
  81         return count;
  82 }
  83
  84 static int pwm_ir_probe(struct platform_device *pdev)
  85 {
  86         struct pwm_ir *pwm_ir;
  87         struct rc_dev *rcdev;
  88         int rc;
  89
  90         pwm_ir = devm_kmalloc(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL);
  91         if (!pwm_ir)
  92                 return -ENOMEM;
  93
  94         pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL);
  95         if (IS_ERR(pwm_ir->pwm))
  96                 return PTR_ERR(pwm_ir->pwm);
  97
  98         pwm_ir->carrier = 38000;
  99         pwm_ir->duty_cycle = 50;
 100
 101         rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
 102         if (!rcdev)
 103                 return -ENOMEM;
 104
 105         rcdev->priv = pwm_ir;
 106         rcdev->driver_name = DRIVER_NAME;
 107         rcdev->device_name = DEVICE_NAME;
 108         rcdev->tx_ir = pwm_ir_tx;
 109         rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
 110         rcdev->s_tx_carrier = pwm_ir_set_carrier;
 111
 112         rc = devm_rc_register_device(&pdev->dev, rcdev);
 113         if (rc < 0)
 114                 dev_err(&pdev->dev, "failed to register rc device\n");
 115
 116         return rc;
 117 }
 118
 119 static struct platform_driver pwm_ir_driver = {
 120         .probe = pwm_ir_probe,
 121         .driver = {
 122                 .name   = DRIVER_NAME,
 123                 .of_match_table = of_match_ptr(pwm_ir_of_match),
 124         },
 125 };
 126 module_platform_driver(pwm_ir_driver);
 127
 128 MODULE_DESCRIPTION("PWM IR Transmitter");
 129 MODULE_AUTHOR("Sean Young <sean@mess.org>");
 130 MODULE_LICENSE("GPL");