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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>
/* 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 */
const struct pps_gpio_platform_data *pdata;
};
/*
* 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->pdata->gpio_pin);
if ((rising_edge && !info->pdata->assert_falling_edge) ||
(!rising_edge && info->pdata->assert_falling_edge))
pps_event(info->pps, &ts, PPS_CAPTUREASSERT, NULL);
else if (info->pdata->capture_clear &&
((rising_edge && info->pdata->assert_falling_edge) ||
(!rising_edge && !info->pdata->assert_falling_edge)))
pps_event(info->pps, &ts, PPS_CAPTURECLEAR, NULL);
return IRQ_HANDLED;
}
static int pps_gpio_setup(struct platform_device *pdev)
{
int ret;
const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
ret = gpio_request(pdata->gpio_pin, pdata->gpio_label);
if (ret) {
pr_warning("failed to request GPIO %u\n", pdata->gpio_pin);
return -EINVAL;
}
ret = gpio_direction_input(pdata->gpio_pin);
if (ret) {
pr_warning("failed to set pin direction\n");
gpio_free(pdata->gpio_pin);
return -EINVAL;
}
return 0;
}
static unsigned long
get_irqf_trigger_flags(const struct pps_gpio_platform_data *pdata)
{
unsigned long flags = pdata->assert_falling_edge ?
IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
if (pdata->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 irq;
int ret;
int err;
int pps_default_params;
const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
/* GPIO setup */
ret = pps_gpio_setup(pdev);
if (ret)
return -EINVAL;
/* IRQ setup */
irq = gpio_to_irq(pdata->gpio_pin);
if (irq < 0) {
pr_err("failed to map GPIO to IRQ: %d\n", irq);
err = -EINVAL;
goto return_error;
}
/* allocate space for device info */
data = kzalloc(sizeof(struct pps_gpio_device_data), GFP_KERNEL);
if (data == NULL) {
err = -ENOMEM;
goto return_error;
}
/* initialize PPS specific parts of the bookkeeping data structure. */
data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
if (pdata->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 (pdata->capture_clear)
pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
data->pps = pps_register_source(&data->info, pps_default_params);
if (data->pps == NULL) {
kfree(data);
pr_err("failed to register IRQ %d as PPS source\n", irq);
err = -EINVAL;
goto return_error;
}
data->irq = irq;
data->pdata = pdata;
/* register IRQ interrupt handler */
ret = request_irq(irq, pps_gpio_irq_handler,
get_irqf_trigger_flags(pdata), data->info.name, data);
if (ret) {
pps_unregister_source(data->pps);
kfree(data);
pr_err("failed to acquire IRQ %d\n", irq);
err = -EINVAL;
goto return_error;
}
platform_set_drvdata(pdev, data);
dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n", irq);
return 0;
return_error:
gpio_free(pdata->gpio_pin);
return err;
}
static int pps_gpio_remove(struct platform_device *pdev)
{
struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
const struct pps_gpio_platform_data *pdata = data->pdata;
platform_set_drvdata(pdev, NULL);
free_irq(data->irq, data);
gpio_free(pdata->gpio_pin);
pps_unregister_source(data->pps);
pr_info("removed IRQ %d as PPS source\n", data->irq);
kfree(data);
return 0;
}
static struct platform_driver pps_gpio_driver = {
.probe = pps_gpio_probe,
.remove = pps_gpio_remove,
.driver = {
.name = PPS_GPIO_NAME,
.owner = THIS_MODULE
},
};
static int __init pps_gpio_init(void)
{
int ret = platform_driver_register(&pps_gpio_driver);
if (ret < 0)
pr_err("failed to register platform driver\n");
return ret;
}
static void __exit pps_gpio_exit(void)
{
platform_driver_unregister(&pps_gpio_driver);
pr_debug("unregistered platform driver\n");
}
module_init(pps_gpio_init);
module_exit(pps_gpio_exit);
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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