target/linux/ar7/files/drivers/char/ar7_gpio.c

   1 /*
   2  * linux/drivers/char/ar7_gpio.c
   3  *
   4  * Copyright (C) 2007 OpenWrt.org
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  */
  20
  21 #include <linux/device.h>
  22 #include <linux/fs.h>
  23 #include <linux/module.h>
  24 #include <linux/errno.h>
  25 #include <linux/kernel.h>
  26 #include <linux/init.h>
  27 #include <linux/platform_device.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/io.h>
  30
  31 #include <linux/types.h>
  32 #include <linux/cdev.h>
  33 #include <gpio.h>
  34
  35 #define DRVNAME "ar7_gpio"
  36 #define LONGNAME "TI AR7 GPIOs Driver"
  37
  38 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  39 MODULE_DESCRIPTION(LONGNAME);
  40 MODULE_LICENSE("GPL");
  41
  42 static int ar7_gpio_major = 0;
  43
  44 static ssize_t ar7_gpio_write(struct file *file, const char __user *buf,
  45         size_t len, loff_t *ppos)
  46 {
  47         int pin = iminor(file->f_dentry->d_inode);
  48         size_t i;
  49
  50         for (i = 0; i < len; ++i) {
  51                 char c;
  52                 if (get_user(c, buf + i))
  53                         return -EFAULT;
  54                 switch (c) {
  55                 case '0':
  56                         gpio_set_value(pin, 0);
  57                         break;
  58                 case '1':
  59                         gpio_set_value(pin, 1);
  60                         break;
  61                 case 'd':
  62                 case 'D':
  63                         ar7_gpio_disable(pin);
  64                         break;
  65                 case 'e':
  66                 case 'E':
  67                         ar7_gpio_enable(pin);
  68                         break;
  69                 case 'i':
  70                 case 'I':
  71                 case '<':
  72                         gpio_direction_input(pin);
  73                         break;
  74                 case 'o':
  75                 case 'O':
  76                 case '>':
  77                         gpio_direction_output(pin);
  78                         break;
  79                 default:
  80                         return -EINVAL;
  81                 }
  82         }
  83
  84         return len;
  85 }
  86
  87 static ssize_t ar7_gpio_read(struct file *file, char __user * buf,
  88         size_t len, loff_t * ppos)
  89 {
  90         int pin = iminor(file->f_dentry->d_inode);
  91         int value;
  92
  93         value = gpio_get_value(pin);
  94         if (put_user(value ? '1' : '0', buf))
  95                 return -EFAULT;
  96
  97         return 1;
  98 }
  99
 100 static int ar7_gpio_open(struct inode *inode, struct file *file)
 101 {
 102         int m = iminor(inode);
 103
 104         if (m >= AR7_GPIO_MAX)
 105                 return -EINVAL;
 106
 107         return nonseekable_open(inode, file);
 108 }
 109
 110 static int ar7_gpio_release(struct inode *inode, struct file *file)
 111 {
 112         return 0;
 113 }
 114
 115 static const struct file_operations ar7_gpio_fops = {
 116         .owner   = THIS_MODULE,
 117         .write   = ar7_gpio_write,
 118         .read    = ar7_gpio_read,
 119         .open    = ar7_gpio_open,
 120         .release = ar7_gpio_release,
 121         .llseek  = no_llseek,
 122 };
 123
 124 static struct platform_device *ar7_gpio_device;
 125
 126 static int __init ar7_gpio_init(void)
 127 {
 128         int rc;
 129
 130         ar7_gpio_device = platform_device_alloc(DRVNAME, -1);
 131         if (!ar7_gpio_device)
 132                 return -ENOMEM;
 133
 134         rc = platform_device_add(ar7_gpio_device);
 135         if (rc < 0)
 136                 goto out_put;
 137
 138         rc = register_chrdev(ar7_gpio_major, DRVNAME, &ar7_gpio_fops);
 139         if (rc < 0)
 140                 goto out_put;
 141
 142         ar7_gpio_major = rc;
 143
 144         rc = 0;
 145
 146         goto out;
 147
 148 out_put:
 149         platform_device_put(ar7_gpio_device);
 150 out:
 151         return rc;
 152 }
 153
 154 static void __exit ar7_gpio_exit(void)
 155 {
 156         unregister_chrdev(ar7_gpio_major, DRVNAME);
 157         platform_device_unregister(ar7_gpio_device);
 158 }
 159
 160 module_init(ar7_gpio_init);
 161 module_exit(ar7_gpio_exit);