LXR linux/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
  26struct pwm_ir {
  27        struct pwm_device *pwm;
  28        unsigned int carrier;
  29        unsigned int duty_cycle;
  30};
  31
  32static const struct of_device_id pwm_ir_of_match[] = {
  33        { .compatible = "pwm-ir-tx", },
  34        { },
  35};
  36MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
  37
  38static 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
  47static 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
  59static 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
  92static 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
 127static 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};
 134module_platform_driver(pwm_ir_driver);
 135
 136MODULE_DESCRIPTION("PWM IR Transmitter");
 137MODULE_AUTHOR("Sean Young <sean@mess.org>");
 138MODULE_LICENSE("GPL");
 139