target/linux/ar7-2.6/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
  34 #include <asm/gpio.h>
  35
  36 #define DRVNAME "ar7_gpio"
  37 #define LONGNAME "TI AR7 GPIOs Driver"
  38
  39 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  40 MODULE_DESCRIPTION(LONGNAME);
  41 MODULE_LICENSE("GPL");
  42
  43 static int ar7_gpio_major = 0;
  44
  45 static ssize_t ar7_gpio_write(struct file *file, const char __user *buf,
  46         size_t len, loff_t *ppos)
  47 {
  48         int pin = iminor(file->f_dentry->d_inode);
  49         size_t i;
  50
  51         for (i = 0; i < len; ++i) {
  52                 char c;
  53                 if (get_user(c, buf + i))
  54                         return -EFAULT;
  55                 switch (c) {
  56                 case '0':
  57                         gpio_set_value(pin, 0);
  58                         break;
  59                 case '1':
  60                         gpio_set_value(pin, 1);
  61                         break;
  62                 case 'd':
  63                 case 'D':
  64                         ar7_gpio_disable(pin);
  65                         break;
  66                 case 'e':
  67                 case 'E':
  68                         ar7_gpio_enable(pin);
  69                         break;
  70                 case 'i':
  71                 case 'I':
  72                 case '<':
  73                         gpio_direction_input(pin);
  74                         break;
  75                 case 'o':
  76                 case 'O':
  77                 case '>':
  78                         gpio_direction_output(pin);
  79                         break;
  80                 default:
  81                         return -EINVAL;
  82                 }
  83         }
  84
  85         return len;
  86 }
  87
  88 static ssize_t ar7_gpio_read(struct file *file, char __user * buf,
  89         size_t len, loff_t * ppos)
  90 {
  91         int pin = iminor(file->f_dentry->d_inode);
  92         int value;
  93
  94         value = gpio_get_value(pin);
  95         if (put_user(value ? '1' : '0', buf))
  96                 return -EFAULT;
  97
  98         return 1;
  99 }
 100
 101 static int ar7_gpio_open(struct inode *inode, struct file *file)
 102 {
 103         int m = iminor(inode);
 104
 105         if (m >= AR7_GPIO_MAX)
 106                 return -EINVAL;
 107
 108         return nonseekable_open(inode, file);
 109 }
 110
 111 static int ar7_gpio_release(struct inode *inode, struct file *file)
 112 {
 113         return 0;
 114 }
 115
 116 static const struct file_operations ar7_gpio_fops = {
 117         .owner   = THIS_MODULE,
 118         .write   = ar7_gpio_write,
 119         .read    = ar7_gpio_read,
 120         .open    = ar7_gpio_open,
 121         .release = ar7_gpio_release,
 122         .llseek  = no_llseek,
 123 };
 124
 125 static struct platform_device *ar7_gpio_device;
 126
 127 static int __init ar7_gpio_init(void)
 128 {
 129         int rc;
 130
 131         ar7_gpio_device = platform_device_alloc(DRVNAME, -1);
 132         if (!ar7_gpio_device)
 133                 return -ENOMEM;
 134
 135         rc = platform_device_add(ar7_gpio_device);
 136         if (rc < 0)
 137                 goto out_put;
 138
 139         rc = register_chrdev(ar7_gpio_major, DRVNAME, &ar7_gpio_fops);
 140         if (rc < 0)
 141                 goto out_put;
 142
 143         ar7_gpio_major = rc;
 144
 145         goto out;
 146
 147 out_put:
 148         platform_device_put(ar7_gpio_device);
 149 out:
 150         return rc;
 151 }
 152
 153 static void __exit ar7_gpio_exit(void)
 154 {
 155         unregister_chrdev(ar7_gpio_major, DRVNAME);
 156         platform_device_unregister(ar7_gpio_device);
 157 }
 158
 159 module_init(ar7_gpio_init);
 160 module_exit(ar7_gpio_exit);