diff options
Diffstat (limited to 'drivers/media/rc/pwm-ir-tx.c')
| -rw-r--r-- | drivers/media/rc/pwm-ir-tx.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/drivers/media/rc/pwm-ir-tx.c b/drivers/media/rc/pwm-ir-tx.c new file mode 100644 index 000000000000..047472dc9244 --- /dev/null +++ b/drivers/media/rc/pwm-ir-tx.c @@ -0,0 +1,200 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2017 Sean Young <sean@mess.org> + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/pwm.h> +#include <linux/delay.h> +#include <linux/slab.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/hrtimer.h> +#include <linux/completion.h> +#include <media/rc-core.h> + +#define DRIVER_NAME "pwm-ir-tx" +#define DEVICE_NAME "PWM IR Transmitter" + +struct pwm_ir { + struct pwm_device *pwm; + struct hrtimer timer; + struct completion tx_done; + struct pwm_state *state; + u32 carrier; + u32 duty_cycle; + const unsigned int *txbuf; + unsigned int txbuf_len; + unsigned int txbuf_index; +}; + +static const struct of_device_id pwm_ir_of_match[] = { + { .compatible = "pwm-ir-tx", }, + { .compatible = "nokia,n900-ir" }, + { }, +}; +MODULE_DEVICE_TABLE(of, pwm_ir_of_match); + +static int pwm_ir_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle) +{ + struct pwm_ir *pwm_ir = dev->priv; + + pwm_ir->duty_cycle = duty_cycle; + + return 0; +} + +static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier) +{ + struct pwm_ir *pwm_ir = dev->priv; + + if (!carrier) + return -EINVAL; + + pwm_ir->carrier = carrier; + + return 0; +} + +static int pwm_ir_tx_sleep(struct rc_dev *dev, unsigned int *txbuf, + unsigned int count) +{ + struct pwm_ir *pwm_ir = dev->priv; + struct pwm_device *pwm = pwm_ir->pwm; + struct pwm_state state; + int i; + ktime_t edge; + long delta; + + pwm_init_state(pwm, &state); + + state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier); + pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100); + + edge = ktime_get(); + + for (i = 0; i < count; i++) { + state.enabled = !(i % 2); + pwm_apply_might_sleep(pwm, &state); + + edge = ktime_add_us(edge, txbuf[i]); + delta = ktime_us_delta(edge, ktime_get()); + if (delta > 0) + usleep_range(delta, delta + 10); + } + + state.enabled = false; + pwm_apply_might_sleep(pwm, &state); + + return count; +} + +static int pwm_ir_tx_atomic(struct rc_dev *dev, unsigned int *txbuf, + unsigned int count) +{ + struct pwm_ir *pwm_ir = dev->priv; + struct pwm_device *pwm = pwm_ir->pwm; + struct pwm_state state; + + pwm_init_state(pwm, &state); + + state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier); + pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100); + + pwm_ir->txbuf = txbuf; + pwm_ir->txbuf_len = count; + pwm_ir->txbuf_index = 0; + pwm_ir->state = &state; + + hrtimer_start(&pwm_ir->timer, 0, HRTIMER_MODE_REL); + + wait_for_completion(&pwm_ir->tx_done); + + return count; +} + +static enum hrtimer_restart pwm_ir_timer(struct hrtimer *timer) +{ + struct pwm_ir *pwm_ir = container_of(timer, struct pwm_ir, timer); + + /* + * If we happen to hit an odd latency spike, loop through the + * pulses until we catch up. + */ + do { + u64 ns; + + pwm_ir->state->enabled = !(pwm_ir->txbuf_index % 2); + pwm_apply_atomic(pwm_ir->pwm, pwm_ir->state); + + if (pwm_ir->txbuf_index >= pwm_ir->txbuf_len) { + complete(&pwm_ir->tx_done); + + return HRTIMER_NORESTART; + } + + ns = US_TO_NS(pwm_ir->txbuf[pwm_ir->txbuf_index]); + hrtimer_add_expires_ns(timer, ns); + + pwm_ir->txbuf_index++; + } while (hrtimer_expires_remaining(timer) > 0); + + return HRTIMER_RESTART; +} + +static int pwm_ir_probe(struct platform_device *pdev) +{ + struct pwm_ir *pwm_ir; + struct rc_dev *rcdev; + int rc; + + pwm_ir = devm_kmalloc(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL); + if (!pwm_ir) + return -ENOMEM; + + pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL); + if (IS_ERR(pwm_ir->pwm)) + return PTR_ERR(pwm_ir->pwm); + + pwm_ir->carrier = 38000; + pwm_ir->duty_cycle = 50; + + rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX); + if (!rcdev) + return -ENOMEM; + + if (pwm_might_sleep(pwm_ir->pwm)) { + dev_info(&pdev->dev, "TX will not be accurate as PWM device might sleep\n"); + rcdev->tx_ir = pwm_ir_tx_sleep; + } else { + init_completion(&pwm_ir->tx_done); + hrtimer_setup(&pwm_ir->timer, pwm_ir_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + rcdev->tx_ir = pwm_ir_tx_atomic; + } + + rcdev->priv = pwm_ir; + rcdev->driver_name = DRIVER_NAME; + rcdev->device_name = DEVICE_NAME; + rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle; + rcdev->s_tx_carrier = pwm_ir_set_carrier; + + rc = devm_rc_register_device(&pdev->dev, rcdev); + if (rc < 0) + dev_err(&pdev->dev, "failed to register rc device\n"); + + return rc; +} + +static struct platform_driver pwm_ir_driver = { + .probe = pwm_ir_probe, + .driver = { + .name = DRIVER_NAME, + .of_match_table = pwm_ir_of_match, + }, +}; +module_platform_driver(pwm_ir_driver); + +MODULE_DESCRIPTION("PWM IR Transmitter"); +MODULE_AUTHOR("Sean Young <sean@mess.org>"); +MODULE_LICENSE("GPL"); |