media/rc/pwm-ir-tx.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Copyright (C) 2017 Sean Young <sean@mess.org>
0004  */
0005
0006 #include <linux/kernel.h>
0007 #include <linux/module.h>
0008 #include <linux/pwm.h>
0009 #include <linux/delay.h>
0010 #include <linux/slab.h>
0011 #include <linux/of.h>
0012 #include <linux/platform_device.h>
0013 #include <media/rc-core.h>
0014
0015 #define DRIVER_NAME "pwm-ir-tx"
0016 #define DEVICE_NAME "PWM IR Transmitter"
0017
0018 struct pwm_ir {
0019     struct pwm_device *pwm;
0020     unsigned int carrier;
0021     unsigned int duty_cycle;
0022 };
0023
0024 static const struct of_device_id pwm_ir_of_match[] = {
0025     { .compatible = "pwm-ir-tx", },
0026     { },
0027 };
0028 MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
0029
0030 static int pwm_ir_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
0031 {
0032     struct pwm_ir *pwm_ir = dev->priv;
0033
0034     pwm_ir->duty_cycle = duty_cycle;
0035
0036     return 0;
0037 }
0038
0039 static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier)
0040 {
0041     struct pwm_ir *pwm_ir = dev->priv;
0042
0043     if (!carrier)
0044         return -EINVAL;
0045
0046     pwm_ir->carrier = carrier;
0047
0048     return 0;
0049 }
0050
0051 static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
0052              unsigned int count)
0053 {
0054     struct pwm_ir *pwm_ir = dev->priv;
0055     struct pwm_device *pwm = pwm_ir->pwm;
0056     struct pwm_state state;
0057     int i;
0058     ktime_t edge;
0059     long delta;
0060
0061     pwm_init_state(pwm, &state);
0062
0063     state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
0064     pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100);
0065
0066     edge = ktime_get();
0067
0068     for (i = 0; i < count; i++) {
0069         state.enabled = !(i % 2);
0070         pwm_apply_state(pwm, &state);
0071
0072         edge = ktime_add_us(edge, txbuf[i]);
0073         delta = ktime_us_delta(edge, ktime_get());
0074         if (delta > 0)
0075             usleep_range(delta, delta + 10);
0076     }
0077
0078     state.enabled = false;
0079     pwm_apply_state(pwm, &state);
0080
0081     return count;
0082 }
0083
0084 static int pwm_ir_probe(struct platform_device *pdev)
0085 {
0086     struct pwm_ir *pwm_ir;
0087     struct rc_dev *rcdev;
0088     int rc;
0089
0090     pwm_ir = devm_kmalloc(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL);
0091     if (!pwm_ir)
0092         return -ENOMEM;
0093
0094     pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL);
0095     if (IS_ERR(pwm_ir->pwm))
0096         return PTR_ERR(pwm_ir->pwm);
0097
0098     pwm_ir->carrier = 38000;
0099     pwm_ir->duty_cycle = 50;
0100
0101     rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
0102     if (!rcdev)
0103         return -ENOMEM;
0104
0105     rcdev->priv = pwm_ir;
0106     rcdev->driver_name = DRIVER_NAME;
0107     rcdev->device_name = DEVICE_NAME;
0108     rcdev->tx_ir = pwm_ir_tx;
0109     rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
0110     rcdev->s_tx_carrier = pwm_ir_set_carrier;
0111
0112     rc = devm_rc_register_device(&pdev->dev, rcdev);
0113     if (rc < 0)
0114         dev_err(&pdev->dev, "failed to register rc device\n");
0115
0116     return rc;
0117 }
0118
0119 static struct platform_driver pwm_ir_driver = {
0120     .probe = pwm_ir_probe,
0121     .driver = {
0122         .name   = DRIVER_NAME,
0123         .of_match_table = of_match_ptr(pwm_ir_of_match),
0124     },
0125 };
0126 module_platform_driver(pwm_ir_driver);
0127
0128 MODULE_DESCRIPTION("PWM IR Transmitter");
0129 MODULE_AUTHOR("Sean Young <sean@mess.org>");
0130 MODULE_LICENSE("GPL");