target/linux/generic-2.6/files/drivers/gpio/gpio_dev.c

   1 /*
   2  * character device wrapper for generic gpio layer
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA
  17  *
  18  * Feedback, Bugs...  blogic@openwrt.org
  19  *
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/errno.h>
  24 #include <linux/init.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/io.h>
  27 #include <asm/gpio.h>
  28 #include <linux/init.h>
  29 #include <linux/genhd.h>
  30 #include <linux/device.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/gpio_dev.h>
  33
  34 #define DRVNAME         "gpiodev"
  35 #define DEVNAME         "gpio"
  36
  37 static int dev_major;
  38 static int gpio_is_open = 0;
  39 unsigned int gpio_access_mask = 0;
  40 static struct class *gpio_class;
  41
  42 static int
  43 gpio_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg)
  44 {
  45         int retval = 0;
  46
  47         if ((arg & gpio_access_mask) != arg)
  48         {
  49                 retval = -EINVAL;
  50                 goto out;
  51         }
  52
  53         switch (cmd)
  54         {
  55         case GPIO_GET:
  56                 retval = gpio_get_value(arg);
  57                 break;
  58
  59         case GPIO_SET:
  60                 gpio_set_value(arg, 0);
  61                 break;
  62
  63         case GPIO_CLEAR:
  64                 gpio_set_value(arg, 0);
  65                 break;
  66
  67         case GPIO_DIR_IN:
  68                 gpio_direction_input(arg);
  69                 break;
  70
  71         case GPIO_DIR_OUT:
  72                 gpio_direction_output(arg, 0);
  73                 break;
  74
  75         default:
  76                 retval = -EINVAL;
  77                 break;
  78         }
  79
  80 out:
  81         return retval;
  82 }
  83
  84 static int
  85 gpio_open(struct inode *inode, struct file *file)
  86 {
  87         int result = 0;
  88         unsigned int dev_minor = MINOR(inode->i_rdev);
  89
  90         if (dev_minor != 0)
  91         {
  92                 printk(KERN_ERR DRVNAME ": trying to access unknown minor device -> %d\n", dev_minor);
  93                 result = -ENODEV;
  94                 goto out;
  95         }
  96
  97         if (gpio_is_open)
  98         {
  99                 printk(KERN_ERR DRVNAME ": Device with minor ID %d already in use\n", dev_minor);
 100                 result = -EBUSY;
 101                 goto out;
 102         }
 103
 104         gpio_is_open = 1;
 105
 106 out:
 107         return result;
 108 }
 109
 110 static int
 111 gpio_close(struct inode * inode, struct file * file)
 112 {
 113         gpio_is_open = 0;
 114
 115         return 0;
 116 }
 117
 118 struct file_operations gpio_fops = {
 119         ioctl:          gpio_ioctl,
 120         open:           gpio_open,
 121         release:        gpio_close
 122 };
 123
 124 static int
 125 gpio_probe(struct platform_device *dev)
 126 {
 127         int result = 0;
 128
 129         dev_major = register_chrdev(0, DEVNAME, &gpio_fops);
 130         if (!dev_major)
 131         {
 132                 printk(KERN_ERR DRVNAME ": Error whilst opening %s \n", DEVNAME);
 133                 result = -ENODEV;
 134                 goto out;
 135         }
 136
 137         gpio_class = class_create(THIS_MODULE, DEVNAME);
 138         class_device_create(gpio_class, NULL, MKDEV(dev_major, 0), NULL, DEVNAME);
 139
 140         printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major);
 141
 142         if (dev->num_resources != 1)
 143         {
 144                 printk(KERN_ERR DRVNAME ": device may only have 1 resource\n");
 145                 result = -ENODEV;
 146                 goto out;
 147         }
 148
 149         gpio_access_mask = dev->resource[0].start;
 150
 151         printk(KERN_INFO DRVNAME ": gpio platform device registered with access mask %08X\n", gpio_access_mask);
 152 out:
 153         return result;
 154 }
 155
 156 static int
 157 gpio_remove(struct platform_device *dev)
 158 {
 159         unregister_chrdev(dev_major, DEVNAME);
 160         return 0;
 161 }
 162
 163 static struct
 164 platform_driver gpio_driver = {
 165         .probe = gpio_probe,
 166         .remove = gpio_remove,
 167         .driver = {
 168                 .name = "GPIODEV",
 169                 .owner = THIS_MODULE,
 170         },
 171 };
 172
 173 static int __init
 174 gpio_mod_init(void)
 175 {
 176         int ret = platform_driver_register(&gpio_driver);
 177         if (ret)
 178                 printk(KERN_INFO DRVNAME ": Error registering platfom driver!");
 179
 180         return ret;
 181 }
 182
 183 static void __exit
 184 gpio_mod_exit(void)
 185 {
 186         platform_driver_unregister(&gpio_driver);
 187 }
 188
 189 module_init (gpio_mod_init);
 190 module_exit (gpio_mod_exit);
 191
 192 MODULE_LICENSE("GPL");
 193 MODULE_AUTHOR("John Crispin / OpenWrt");
 194 MODULE_DESCRIPTION("Character device for for generic gpio api");