1 files changed, 275 insertions, 0 deletions

diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c
new file mode 100644
index 000000000..e0de1df2e
--- /dev/null
+++ b/drivers/pps/clients/pps-gpio.c
@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * pps-gpio.c -- PPS client driver using GPIO
+ *
+ * Copyright (C) 2010 Ricardo Martins <rasm@fe.up.pt>
+ * Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
+ */
+
+#define PPS_GPIO_NAME "pps-gpio"
+#define pr_fmt(fmt) PPS_GPIO_NAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/pps_kernel.h>
+#include <linux/pps-gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/list.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+
+/* Info for each registered platform device */
+struct pps_gpio_device_data {
+	int irq;			/* IRQ used as PPS source */
+	struct pps_device *pps;		/* PPS source device */
+	struct pps_source_info info;	/* PPS source information */
+	struct gpio_desc *gpio_pin;	/* GPIO port descriptors */
+	struct gpio_desc *echo_pin;
+	struct timer_list echo_timer;	/* timer to reset echo active state */
+	bool assert_falling_edge;
+	bool capture_clear;
+	unsigned int echo_active_ms;	/* PPS echo active duration */
+	unsigned long echo_timeout;	/* timer timeout value in jiffies */
+};
+
+/*
+ * Report the PPS event
+ */
+
+static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
+{
+	const struct pps_gpio_device_data *info;
+	struct pps_event_time ts;
+	int rising_edge;
+
+	/* Get the time stamp first */
+	pps_get_ts(&ts);
+
+	info = data;
+
+	rising_edge = gpiod_get_value(info->gpio_pin);
+	if ((rising_edge && !info->assert_falling_edge) ||
+			(!rising_edge && info->assert_falling_edge))
+		pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
+	else if (info->capture_clear &&
+			((rising_edge && info->assert_falling_edge) ||
+			(!rising_edge && !info->assert_falling_edge)))
+		pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
+
+	return IRQ_HANDLED;
+}
+
+/* This function will only be called when an ECHO GPIO is defined */
+static void pps_gpio_echo(struct pps_device *pps, int event, void *data)
+{
+	/* add_timer() needs to write into info->echo_timer */
+	struct pps_gpio_device_data *info = data;
+
+	switch (event) {
+	case PPS_CAPTUREASSERT:
+		if (pps->params.mode & PPS_ECHOASSERT)
+			gpiod_set_value(info->echo_pin, 1);
+		break;
+
+	case PPS_CAPTURECLEAR:
+		if (pps->params.mode & PPS_ECHOCLEAR)
+			gpiod_set_value(info->echo_pin, 1);
+		break;
+	}
+
+	/* fire the timer */
+	if (info->pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) {
+		info->echo_timer.expires = jiffies + info->echo_timeout;
+		add_timer(&info->echo_timer);
+	}
+}
+
+/* Timer callback to reset the echo pin to the inactive state */
+static void pps_gpio_echo_timer_callback(struct timer_list *t)
+{
+	const struct pps_gpio_device_data *info;
+
+	info = from_timer(info, t, echo_timer);
+
+	gpiod_set_value(info->echo_pin, 0);
+}
+
+static int pps_gpio_setup(struct platform_device *pdev)
+{
+	struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
+	struct device_node *np = pdev->dev.of_node;
+	int ret;
+	u32 value;
+
+	data->gpio_pin = devm_gpiod_get(&pdev->dev,
+		NULL,	/* request "gpios" */
+		GPIOD_IN);
+	if (IS_ERR(data->gpio_pin)) {
+		dev_err(&pdev->dev,
+			"failed to request PPS GPIO\n");
+		return PTR_ERR(data->gpio_pin);
+	}
+
+	data->echo_pin = devm_gpiod_get_optional(&pdev->dev,
+			"echo",
+			GPIOD_OUT_LOW);
+	if (data->echo_pin) {
+		if (IS_ERR(data->echo_pin)) {
+			dev_err(&pdev->dev, "failed to request ECHO GPIO\n");
+			return PTR_ERR(data->echo_pin);
+		}
+
+		ret = of_property_read_u32(np,
+			"echo-active-ms",
+			&value);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"failed to get echo-active-ms from OF\n");
+			return ret;
+		}
+		data->echo_active_ms = value;
+		/* sanity check on echo_active_ms */
+		if (!data->echo_active_ms || data->echo_active_ms > 999) {
+			dev_err(&pdev->dev,
+				"echo-active-ms: %u - bad value from OF\n",
+				data->echo_active_ms);
+			return -EINVAL;
+		}
+	}
+
+	if (of_property_read_bool(np, "assert-falling-edge"))
+		data->assert_falling_edge = true;
+	return 0;
+}
+
+static unsigned long
+get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
+{
+	unsigned long flags = data->assert_falling_edge ?
+		IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
+
+	if (data->capture_clear) {
+		flags |= ((flags & IRQF_TRIGGER_RISING) ?
+				IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
+	}
+
+	return flags;
+}
+
+static int pps_gpio_probe(struct platform_device *pdev)
+{
+	struct pps_gpio_device_data *data;
+	int ret;
+	int pps_default_params;
+	const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
+
+	/* allocate space for device info */
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, data);
+
+	/* GPIO setup */
+	if (pdata) {
+		data->gpio_pin = pdata->gpio_pin;
+		data->echo_pin = pdata->echo_pin;
+
+		data->assert_falling_edge = pdata->assert_falling_edge;
+		data->capture_clear = pdata->capture_clear;
+		data->echo_active_ms = pdata->echo_active_ms;
+	} else {
+		ret = pps_gpio_setup(pdev);
+		if (ret)
+			return -EINVAL;
+	}
+
+	/* IRQ setup */
+	ret = gpiod_to_irq(data->gpio_pin);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret);
+		return -EINVAL;
+	}
+	data->irq = ret;
+
+	/* initialize PPS specific parts of the bookkeeping data structure. */
+	data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
+		PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
+	if (data->capture_clear)
+		data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
+			PPS_ECHOCLEAR;
+	data->info.owner = THIS_MODULE;
+	snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
+		 pdev->name, pdev->id);
+	if (data->echo_pin) {
+		data->info.echo = pps_gpio_echo;
+		data->echo_timeout = msecs_to_jiffies(data->echo_active_ms);
+		timer_setup(&data->echo_timer, pps_gpio_echo_timer_callback, 0);
+	}
+
+	/* register PPS source */
+	pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
+	if (data->capture_clear)
+		pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
+	data->pps = pps_register_source(&data->info, pps_default_params);
+	if (IS_ERR(data->pps)) {
+		dev_err(&pdev->dev, "failed to register IRQ %d as PPS source\n",
+			data->irq);
+		return PTR_ERR(data->pps);
+	}
+
+	/* register IRQ interrupt handler */
+	ret = devm_request_irq(&pdev->dev, data->irq, pps_gpio_irq_handler,
+			get_irqf_trigger_flags(data), data->info.name, data);
+	if (ret) {
+		pps_unregister_source(data->pps);
+		dev_err(&pdev->dev, "failed to acquire IRQ %d\n", data->irq);
+		return -EINVAL;
+	}
+
+	dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n",
+		 data->irq);
+
+	return 0;
+}
+
+static int pps_gpio_remove(struct platform_device *pdev)
+{
+	struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
+
+	pps_unregister_source(data->pps);
+	if (data->echo_pin) {
+		del_timer_sync(&data->echo_timer);
+		/* reset echo pin in any case */
+		gpiod_set_value(data->echo_pin, 0);
+	}
+	dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
+	return 0;
+}
+
+static const struct of_device_id pps_gpio_dt_ids[] = {
+	{ .compatible = "pps-gpio", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
+
+static struct platform_driver pps_gpio_driver = {
+	.probe		= pps_gpio_probe,
+	.remove		= pps_gpio_remove,
+	.driver		= {
+		.name	= PPS_GPIO_NAME,
+		.of_match_table	= pps_gpio_dt_ids,
+	},
+};
+
+module_platform_driver(pps_gpio_driver);
+MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
+MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
+MODULE_DESCRIPTION("Use GPIO pin as PPS source");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.2.0");