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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright (C) 2017 Sean Young <sean@mess.org>4 */5 6#include <linux/kernel.h>7#include <linux/module.h>8#include <linux/gpio/consumer.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 "gpio-ir-tx"16#define DEVICE_NAME "GPIO IR Bit Banging Transmitter"17 18struct gpio_ir {19 struct gpio_desc *gpio;20 unsigned int carrier;21 unsigned int duty_cycle;22};23 24static const struct of_device_id gpio_ir_tx_of_match[] = {25 { .compatible = "gpio-ir-tx", },26 { },27};28MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match);29 30static int gpio_ir_tx_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)31{32 struct gpio_ir *gpio_ir = dev->priv;33 34 gpio_ir->duty_cycle = duty_cycle;35 36 return 0;37}38 39static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)40{41 struct gpio_ir *gpio_ir = dev->priv;42 43 if (carrier > 500000)44 return -EINVAL;45 46 gpio_ir->carrier = carrier;47 48 return 0;49}50 51static void delay_until(ktime_t until)52{53 /*54 * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on55 * m68k ndelay(s64) does not compile; so use s32 rather than s64.56 */57 s32 delta;58 59 while (true) {60 delta = ktime_us_delta(until, ktime_get());61 if (delta <= 0)62 return;63 64 /* udelay more than 1ms may not work */65 if (delta >= 1000) {66 mdelay(delta / 1000);67 continue;68 }69 70 udelay(delta);71 break;72 }73}74 75static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,76 uint count)77{78 ktime_t edge;79 int i;80 81 local_irq_disable();82 83 edge = ktime_get();84 85 for (i = 0; i < count; i++) {86 gpiod_set_value(gpio_ir->gpio, !(i % 2));87 88 edge = ktime_add_us(edge, txbuf[i]);89 delay_until(edge);90 }91 92 gpiod_set_value(gpio_ir->gpio, 0);93}94 95static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,96 uint count)97{98 ktime_t edge;99 /*100 * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on101 * m68k ndelay(s64) does not compile; so use s32 rather than s64.102 */103 s32 delta;104 int i;105 unsigned int pulse, space;106 107 /* Ensure the dividend fits into 32 bit */108 pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100),109 gpio_ir->carrier);110 space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *111 (NSEC_PER_SEC / 100), gpio_ir->carrier);112 113 local_irq_disable();114 115 edge = ktime_get();116 117 for (i = 0; i < count; i++) {118 if (i % 2) {119 // space120 edge = ktime_add_us(edge, txbuf[i]);121 delay_until(edge);122 } else {123 // pulse124 ktime_t last = ktime_add_us(edge, txbuf[i]);125 126 while (ktime_before(ktime_get(), last)) {127 gpiod_set_value(gpio_ir->gpio, 1);128 edge = ktime_add_ns(edge, pulse);129 delta = ktime_to_ns(ktime_sub(edge,130 ktime_get()));131 if (delta > 0)132 ndelay(delta);133 gpiod_set_value(gpio_ir->gpio, 0);134 edge = ktime_add_ns(edge, space);135 delta = ktime_to_ns(ktime_sub(edge,136 ktime_get()));137 if (delta > 0)138 ndelay(delta);139 }140 141 edge = last;142 }143 }144}145 146static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,147 unsigned int count)148{149 struct gpio_ir *gpio_ir = dev->priv;150 unsigned long flags;151 152 local_irq_save(flags);153 if (gpio_ir->carrier)154 gpio_ir_tx_modulated(gpio_ir, txbuf, count);155 else156 gpio_ir_tx_unmodulated(gpio_ir, txbuf, count);157 local_irq_restore(flags);158 159 return count;160}161 162static int gpio_ir_tx_probe(struct platform_device *pdev)163{164 struct gpio_ir *gpio_ir;165 struct rc_dev *rcdev;166 int rc;167 168 gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);169 if (!gpio_ir)170 return -ENOMEM;171 172 rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);173 if (!rcdev)174 return -ENOMEM;175 176 gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);177 if (IS_ERR(gpio_ir->gpio))178 return dev_err_probe(&pdev->dev, PTR_ERR(gpio_ir->gpio),179 "Failed to get gpio\n");180 181 rcdev->priv = gpio_ir;182 rcdev->driver_name = DRIVER_NAME;183 rcdev->device_name = DEVICE_NAME;184 rcdev->tx_ir = gpio_ir_tx;185 rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;186 rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;187 188 gpio_ir->carrier = 38000;189 gpio_ir->duty_cycle = 50;190 191 rc = devm_rc_register_device(&pdev->dev, rcdev);192 if (rc < 0)193 dev_err(&pdev->dev, "failed to register rc device\n");194 195 return rc;196}197 198static struct platform_driver gpio_ir_tx_driver = {199 .probe = gpio_ir_tx_probe,200 .driver = {201 .name = DRIVER_NAME,202 .of_match_table = gpio_ir_tx_of_match,203 },204};205module_platform_driver(gpio_ir_tx_driver);206 207MODULE_DESCRIPTION("GPIO IR Bit Banging Transmitter");208MODULE_AUTHOR("Sean Young <sean@mess.org>");209MODULE_LICENSE("GPL");210