target/linux/generic/files/drivers/char/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  * dpg 20100106
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/errno.h>
  25 #include <linux/init.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/io.h>
  28 #include <asm/gpio.h>
  29 #include <asm/atomic.h>
  30 #include <linux/init.h>
  31 #include <linux/genhd.h>
  32 #include <linux/device.h>
  33 #include <linux/platform_device.h>
  34 #include <linux/gpio_dev.h>
  35 #include <linux/fs.h>
  36
  37 #define DRVNAME         "gpiodev"
  38 #define DEVNAME         "gpio"
  39
  40 static int dev_major;
  41 static struct class *gpiodev_class;
  42
  43
  44 /* third argument of user space ioctl ('arg' here) contains the <pin> */
  45 static int
  46 gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  47 {
  48         int retval = 0;
  49
  50         switch (cmd)
  51         {
  52         case GPIO_GET:
  53                 retval = gpio_get_value(arg);
  54                 break;
  55         case GPIO_SET:
  56                 gpio_set_value(arg, 1);
  57                 break;
  58         case GPIO_CLEAR:
  59                 gpio_set_value(arg, 0);
  60                 break;
  61         case GPIO_DIR_IN:
  62                 retval = gpio_direction_input(arg);
  63                 break;
  64         case GPIO_DIR_OUT:
  65                 retval = gpio_direction_output(arg, 0);
  66                 break;
  67         case GPIO_DIR_HIGH:
  68                 retval = gpio_direction_output(arg, 1);
  69                 break;
  70         case GPIO_REQUEST:
  71                 /* should be first ioctl operation on <pin> */
  72                 retval = gpio_request(arg, DRVNAME);
  73                 break;
  74         case GPIO_FREE:
  75                 /* should be last ioctl operation on <pin> */
  76                 /* may be needed first if previous user missed this ioctl */
  77                 gpio_free(arg);
  78                 break;
  79         case GPIO_CAN_SLEEP:
  80                 retval = gpio_cansleep(arg);
  81                 break;
  82         default:
  83                 retval = -EINVAL;
  84                 /* = -ENOTTY; // correct return but ... */
  85                 break;
  86         }
  87         return retval;
  88 }
  89
  90 /* Allow co-incident opens */
  91 static int
  92 gpio_open(struct inode *inode, struct file *file)
  93 {
  94         int result = 0;
  95         unsigned int dev_minor = MINOR(inode->i_rdev);
  96
  97         if (dev_minor != 0)
  98         {
  99                 printk(KERN_ERR DRVNAME ": trying to access unknown minor device -> %d\n", dev_minor);
 100                 result = -ENODEV;
 101                 goto out;
 102         }
 103 out:
 104         return result;
 105 }
 106
 107 static int
 108 gpio_close(struct inode * inode, struct file * file)
 109 {
 110         /* could track all <pin>s requested by this fd and gpio_free()
 111          * them here
 112          */
 113         return 0;
 114 }
 115
 116 struct file_operations gpio_fops = {
 117         unlocked_ioctl: gpio_ioctl,
 118         open:           gpio_open,
 119         release:        gpio_close
 120 };
 121
 122 static int
 123 gpio_probe(struct platform_device *dev)
 124 {
 125         int result = 0;
 126
 127         dev_major = register_chrdev(0, DEVNAME, &gpio_fops);
 128         if (!dev_major)
 129         {
 130                 printk(KERN_ERR DRVNAME ": Error whilst opening %s \n", DEVNAME);
 131                 result = -ENODEV;
 132                 goto out;
 133         }
 134         gpiodev_class = class_create(THIS_MODULE, DRVNAME);
 135         device_create(gpiodev_class, NULL, MKDEV(dev_major, 0), dev, DEVNAME);
 136         printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major);
 137 out:
 138         return result;
 139 }
 140
 141 static int
 142 gpio_remove(struct platform_device *dev)
 143 {
 144         unregister_chrdev(dev_major, DEVNAME);
 145         return 0;
 146 }
 147
 148 static struct
 149 platform_driver gpio_driver = {
 150         .probe = gpio_probe,
 151         .remove = gpio_remove,
 152         .driver = {
 153                 .name = "GPIODEV",
 154                 .owner = THIS_MODULE,
 155         },
 156 };
 157
 158 static int __init
 159 gpio_mod_init(void)
 160 {
 161         int ret = platform_driver_register(&gpio_driver);
 162         if (ret)
 163                 printk(KERN_INFO DRVNAME ": Error registering platfom driver!\n");
 164
 165         return ret;
 166 }
 167
 168 static void __exit
 169 gpio_mod_exit(void)
 170 {
 171         platform_driver_unregister(&gpio_driver);
 172 }
 173
 174 module_init (gpio_mod_init);
 175 module_exit (gpio_mod_exit);
 176
 177 MODULE_LICENSE("GPL");
 178 MODULE_AUTHOR("John Crispin / OpenWrt +");
 179 MODULE_DESCRIPTION("Character device for for generic gpio api");