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/*
* 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>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#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.h>
#include <linux/list.h>
#include <linux/of_device.h>
#include <linux/of_gpio.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 */
bool assert_falling_edge;
bool capture_clear;
unsigned int gpio_pin;
};
/*
* 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 = gpio_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, NULL);
else if (info->capture_clear &&
((rising_edge && info->assert_falling_edge) ||
(!rising_edge && !info->assert_falling_edge)))
pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL);
return IRQ_HANDLED;
}
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;
const char *gpio_label;
int ret;
int pps_default_params;
const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
struct device_node *np = pdev->dev.of_node;
/* allocate space for device info */
data = devm_kzalloc(&pdev->dev, sizeof(struct pps_gpio_device_data),
GFP_KERNEL);
if (!data)
return -ENOMEM;
if (pdata) {
data->gpio_pin = pdata->gpio_pin;
gpio_label = pdata->gpio_label;
data->assert_falling_edge = pdata->assert_falling_edge;
data->capture_clear = pdata->capture_clear;
} else {
ret = of_get_gpio(np, 0);
if (ret < 0) {
dev_err(&pdev->dev, "failed to get GPIO from device tree\n");
return ret;
}
data->gpio_pin = ret;
gpio_label = PPS_GPIO_NAME;
if (of_get_property(np, "assert-falling-edge", NULL))
data->assert_falling_edge = true;
}
/* GPIO setup */
ret = devm_gpio_request(&pdev->dev, data->gpio_pin, gpio_label);
if (ret) {
dev_err(&pdev->dev, "failed to request GPIO %u\n",
data->gpio_pin);
return ret;
}
ret = gpio_direction_input(data->gpio_pin);
if (ret) {
dev_err(&pdev->dev, "failed to set pin direction\n");
return -EINVAL;
}
/* IRQ setup */
ret = gpio_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);
/* 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 (data->pps == NULL) {
dev_err(&pdev->dev, "failed to register IRQ %d as PPS source\n",
data->irq);
return -EINVAL;
}
/* 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;
}
platform_set_drvdata(pdev, data);
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);
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("1.0.0");
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