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 <linux/hrtimer.h>
  14 #include <linux/completion.h>
  15 #include <media/rc-core.h>
  16
  17 #define DRIVER_NAME     "pwm-ir-tx"
  18 #define DEVICE_NAME     "PWM IR Transmitter"
  19
  20 struct pwm_ir {
  21         struct pwm_device *pwm;
  22         struct hrtimer timer;
  23         struct completion tx_done;
  24         struct pwm_state *state;
  25         u32 carrier;
  26         u32 duty_cycle;
  27         const unsigned int *txbuf;
  28         unsigned int txbuf_len;
  29         unsigned int txbuf_index;
  30 };
  31
  32 static const struct of_device_id pwm_ir_of_match[] = {
  33         { .compatible = "pwm-ir-tx", },
  34         { .compatible = "nokia,n900-ir" },
  35         { },
  36 };
  37 MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
  38
  39 static int pwm_ir_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
  40 {
  41         struct pwm_ir *pwm_ir = dev->priv;
  42
  43         pwm_ir->duty_cycle = duty_cycle;
  44
  45         return 0;
  46 }
  47
  48 static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier)
  49 {
  50         struct pwm_ir *pwm_ir = dev->priv;
  51
  52         if (!carrier)
  53                 return -EINVAL;
  54
  55         pwm_ir->carrier = carrier;
  56
  57         return 0;
  58 }
  59
  60 static int pwm_ir_tx_sleep(struct rc_dev *dev, unsigned int *txbuf,
  61                            unsigned int count)
  62 {
  63         struct pwm_ir *pwm_ir = dev->priv;
  64         struct pwm_device *pwm = pwm_ir->pwm;
  65         struct pwm_state state;
  66         int i;
  67         ktime_t edge;
  68         long delta;
  69
  70         pwm_init_state(pwm, &state);
  71
  72         state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
  73         pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100);
  74
  75         edge = ktime_get();
  76
  77         for (i = 0; i < count; i++) {
  78                 state.enabled = !(i % 2);
  79                 pwm_apply_might_sleep(pwm, &state);
  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         state.enabled = false;
  88         pwm_apply_might_sleep(pwm, &state);
  89
  90         return count;
  91 }
  92
  93 static int pwm_ir_tx_atomic(struct rc_dev *dev, unsigned int *txbuf,
  94                             unsigned int count)
  95 {
  96         struct pwm_ir *pwm_ir = dev->priv;
  97         struct pwm_device *pwm = pwm_ir->pwm;
  98         struct pwm_state state;
  99
 100         pwm_init_state(pwm, &state);
 101
 102         state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
 103         pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100);
 104
 105         pwm_ir->txbuf = txbuf;
 106         pwm_ir->txbuf_len = count;
 107         pwm_ir->txbuf_index = 0;
 108         pwm_ir->state = &state;
 109
 110         hrtimer_start(&pwm_ir->timer, 0, HRTIMER_MODE_REL);
 111
 112         wait_for_completion(&pwm_ir->tx_done);
 113
 114         return count;
 115 }
 116
 117 static enum hrtimer_restart pwm_ir_timer(struct hrtimer *timer)
 118 {
 119         struct pwm_ir *pwm_ir = container_of(timer, struct pwm_ir, timer);
 120         ktime_t now;
 121
 122         /*
 123          * If we happen to hit an odd latency spike, loop through the
 124          * pulses until we catch up.
 125          */
 126         do {
 127                 u64 ns;
 128
 129                 pwm_ir->state->enabled = !(pwm_ir->txbuf_index % 2);
 130                 pwm_apply_atomic(pwm_ir->pwm, pwm_ir->state);
 131
 132                 if (pwm_ir->txbuf_index >= pwm_ir->txbuf_len) {
 133                         complete(&pwm_ir->tx_done);
 134
 135                         return HRTIMER_NORESTART;
 136                 }
 137
 138                 ns = US_TO_NS(pwm_ir->txbuf[pwm_ir->txbuf_index]);
 139                 hrtimer_add_expires_ns(timer, ns);
 140
 141                 pwm_ir->txbuf_index++;
 142
 143                 now = timer->base->get_time();
 144         } while (hrtimer_get_expires_tv64(timer) < now);
 145
 146         return HRTIMER_RESTART;
 147 }
 148
 149 static int pwm_ir_probe(struct platform_device *pdev)
 150 {
 151         struct pwm_ir *pwm_ir;
 152         struct rc_dev *rcdev;
 153         int rc;
 154
 155         pwm_ir = devm_kmalloc(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL);
 156         if (!pwm_ir)
 157                 return -ENOMEM;
 158
 159         pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL);
 160         if (IS_ERR(pwm_ir->pwm))
 161                 return PTR_ERR(pwm_ir->pwm);
 162
 163         pwm_ir->carrier = 38000;
 164         pwm_ir->duty_cycle = 50;
 165
 166         rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
 167         if (!rcdev)
 168                 return -ENOMEM;
 169
 170         if (pwm_might_sleep(pwm_ir->pwm)) {
 171                 dev_info(&pdev->dev, "TX will not be accurate as PWM device might sleep\n");
 172                 rcdev->tx_ir = pwm_ir_tx_sleep;
 173         } else {
 174                 init_completion(&pwm_ir->tx_done);
 175                 hrtimer_init(&pwm_ir->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 176                 pwm_ir->timer.function = pwm_ir_timer;
 177                 rcdev->tx_ir = pwm_ir_tx_atomic;
 178         }
 179
 180         rcdev->priv = pwm_ir;
 181         rcdev->driver_name = DRIVER_NAME;
 182         rcdev->device_name = DEVICE_NAME;
 183         rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
 184         rcdev->s_tx_carrier = pwm_ir_set_carrier;
 185
 186         rc = devm_rc_register_device(&pdev->dev, rcdev);
 187         if (rc < 0)
 188                 dev_err(&pdev->dev, "failed to register rc device\n");
 189
 190         return rc;
 191 }
 192
 193 static struct platform_driver pwm_ir_driver = {
 194         .probe = pwm_ir_probe,
 195         .driver = {
 196                 .name   = DRIVER_NAME,
 197                 .of_match_table = pwm_ir_of_match,
 198         },
 199 };
 200 module_platform_driver(pwm_ir_driver);
 201
 202 MODULE_DESCRIPTION("PWM IR Transmitter");
 203 MODULE_AUTHOR("Sean Young <sean@mess.org>");
 204 MODULE_LICENSE("GPL");