-/*
- * 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");
projects / openwrt.git / blobdiff