media: rc: pwm-ir-tx: add new driver

This is new driver which uses pwm, so it is more power-efficient
than the bit banging gpio-ir-tx driver.

Signed-off-by: Sean Young <[e-mail]>
Reviewed-by: Pavel Machek <[e-mail]>
Tested-by: Matthias Reichl <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

MAINTAINERS

···
 F:	Documentation/hwmon/pwm-fan
 F:	drivers/hwmon/pwm-fan.c
 
+PWM IR Transmitter
+M:	Sean Young <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	drivers/media/rc/pwm-ir-tx.c
+
 PWM SUBSYSTEM
 M:	Thierry Reding <[e-mail]>
 L:	[e-mail]

drivers/media/rc/Kconfig

···
 	   To compile this driver as a module, choose M here: the module will
 	   be called gpio-ir-tx.
 
+config IR_PWM_TX
+	tristate "PWM IR transmitter"
+	depends on RC_CORE
+	depends on LIRC
+	depends on PWM
+	---help---
+	   Say Y if you want to use a PWM based IR transmitter. This is
+	   more power efficient than the bit banging gpio driver.
+
+	   To compile this driver as a module, choose M here: the module will
+	   be called pwm-ir-tx.
+
 config RC_ST
 	tristate "ST remote control receiver"
 	depends on RC_CORE

drivers/media/rc/Makefile

···
 obj-$(CONFIG_RC_LOOPBACK) += rc-loopback.o
 obj-$(CONFIG_IR_GPIO_CIR) += gpio-ir-recv.o
 obj-$(CONFIG_IR_GPIO_TX) += gpio-ir-tx.o
+obj-$(CONFIG_IR_PWM_TX) += pwm-ir-tx.o
 obj-$(CONFIG_IR_IGORPLUGUSB) += igorplugusb.o
 obj-$(CONFIG_IR_IGUANA) += iguanair.o
 obj-$(CONFIG_IR_TTUSBIR) += ttusbir.o

drivers/media/rc/pwm-ir-tx.c

···
+/*
+ * Copyright (C) 2017 Sean Young <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#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 <media/rc-core.h>
+
+#define DRIVER_NAME	"pwm-ir-tx"
+#define DEVICE_NAME	"PWM IR Transmitter"
+
+struct pwm_ir {
+	struct pwm_device *pwm;
+	unsigned int carrier;
+	unsigned int duty_cycle;
+};
+
+static const struct of_device_id pwm_ir_of_match[] = {
+	{ .compatible = "pwm-ir-tx", },
+	{ },
+};
+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(struct rc_dev *dev, unsigned int *txbuf,
+		     unsigned int count)
+{
+	struct pwm_ir *pwm_ir = dev->priv;
+	struct pwm_device *pwm = pwm_ir->pwm;
+	int i, duty, period;
+	ktime_t edge;
+	long delta;
+
+	period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
+	duty = DIV_ROUND_CLOSEST(pwm_ir->duty_cycle * period, 100);
+
+	pwm_config(pwm, duty, period);
+
+	edge = ktime_get();
+
+	for (i = 0; i < count; i++) {
+		if (i % 2) // space
+			pwm_disable(pwm);
+		else
+			pwm_enable(pwm);
+
+		edge = ktime_add_us(edge, txbuf[i]);
+		delta = ktime_us_delta(edge, ktime_get());
+		if (delta > 0)
+			usleep_range(delta, delta + 10);
+	}
+
+	pwm_disable(pwm);
+
+	return count;
+}
+
+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;
+
+	rcdev->priv = pwm_ir;
+	rcdev->driver_name = DRIVER_NAME;
+	rcdev->device_name = DEVICE_NAME;
+	rcdev->tx_ir = pwm_ir_tx;
+	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 = of_match_ptr(pwm_ir_of_match),
+	},
+};
+module_platform_driver(pwm_ir_driver);
+
+MODULE_DESCRIPTION("PWM IR Transmitter");
+MODULE_AUTHOR("Sean Young <[e-mail]>");
+MODULE_LICENSE("GPL");