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"); 205