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/*
* character device wrapper for generic gpio layer
*
* 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., 59 Temple Place, Suite 330, Boston, MA02111-1307USA
*
* Feedback, Bugs... blogic@openwrt.org
*
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/gpio.h>
#include <asm/atomic.h>
#include <linux/init.h>
#include <linux/genhd.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/gpio_dev.h>
#define DRVNAME "gpiodev"
#define DEVNAME "gpio"
static int dev_major;
static unsigned int gpio_access_mask;
static struct class *gpiodev_class;
/* Counter is 1, if the device is not opened and zero (or less) if opened. */
static atomic_t gpio_open_cnt = ATOMIC_INIT(1);
static int
gpio_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg)
{
int retval = 0;
if (((1 << arg) & gpio_access_mask) != (1 << arg))
{
retval = -EINVAL;
goto out;
}
switch (cmd)
{
case GPIO_GET:
retval = gpio_get_value(arg);
break;
case GPIO_SET:
gpio_set_value(arg, 1);
break;
case GPIO_CLEAR:
gpio_set_value(arg, 0);
break;
case GPIO_DIR_IN:
gpio_direction_input(arg);
break;
case GPIO_DIR_OUT:
gpio_direction_output(arg, 0);
break;
default:
retval = -EINVAL;
break;
}
out:
return retval;
}
static int
gpio_open(struct inode *inode, struct file *file)
{
int result = 0;
unsigned int dev_minor = MINOR(inode->i_rdev);
if (dev_minor != 0)
{
printk(KERN_ERR DRVNAME ": trying to access unknown minor device -> %d\n", dev_minor);
result = -ENODEV;
goto out;
}
/* FIXME: We should really allow multiple applications to open the device
* at the same time, as long as the apps access different IO pins.
* The generic gpio-registration functions can be used for that.
* Two new IOCTLs have to be introduced for that. Need to check userspace
* compatibility first. --mb */
if (!atomic_dec_and_test(&gpio_open_cnt)) {
atomic_inc(&gpio_open_cnt);
printk(KERN_ERR DRVNAME ": Device with minor ID %d already in use\n", dev_minor);
result = -EBUSY;
goto out;
}
out:
return result;
}
static int
gpio_close(struct inode * inode, struct file * file)
{
smp_mb__before_atomic_inc();
atomic_inc(&gpio_open_cnt);
return 0;
}
struct file_operations gpio_fops = {
ioctl: gpio_ioctl,
open: gpio_open,
release: gpio_close
};
static int
gpio_probe(struct platform_device *dev)
{
int result = 0;
dev_major = register_chrdev(0, DEVNAME, &gpio_fops);
if (!dev_major)
{
printk(KERN_ERR DRVNAME ": Error whilst opening %s \n", DEVNAME);
result = -ENODEV;
goto out;
}
gpiodev_class = class_create(THIS_MODULE, DRVNAME);
device_create(gpiodev_class, NULL, MKDEV(dev_major, 0), dev, DEVNAME);
printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major);
if (dev->num_resources != 1)
{
printk(KERN_ERR DRVNAME ": device may only have 1 resource\n");
result = -ENODEV;
goto out;
}
gpio_access_mask = dev->resource[0].start;
printk(KERN_INFO DRVNAME ": gpio platform device registered with access mask %08X\n", gpio_access_mask);
out:
return result;
}
static int
gpio_remove(struct platform_device *dev)
{
unregister_chrdev(dev_major, DEVNAME);
return 0;
}
static struct
platform_driver gpio_driver = {
.probe = gpio_probe,
.remove = gpio_remove,
.driver = {
.name = "GPIODEV",
.owner = THIS_MODULE,
},
};
static int __init
gpio_mod_init(void)
{
int ret = platform_driver_register(&gpio_driver);
if (ret)
printk(KERN_INFO DRVNAME ": Error registering platfom driver!");
return ret;
}
static void __exit
gpio_mod_exit(void)
{
platform_driver_unregister(&gpio_driver);
}
module_init (gpio_mod_init);
module_exit (gpio_mod_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Crispin / OpenWrt");
MODULE_DESCRIPTION("Character device for for generic gpio api");
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