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 <linux/uaccess.h>
  29 #include <linux/io.h>
  30 #include <linux/types.h>
  31 #include <linux/cdev.h>
  32 #include <gpio.h>
  33
  34 #define DRVNAME "ar7_gpio"
  35 #define LONGNAME "TI AR7 GPIOs Driver"
  36
  37 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  38 MODULE_DESCRIPTION(LONGNAME);
  39 MODULE_LICENSE("GPL");
  40
  41 static int ar7_gpio_major;
  42
  43 static ssize_t ar7_gpio_write(struct file *file, const char __user *buf,
  44         size_t len, loff_t *ppos)
  45 {
  46         int pin = iminor(file->f_dentry->d_inode);
  47         size_t i;
  48
  49         for (i = 0; i < len; ++i) {
  50                 char c;
  51                 if (get_user(c, buf + i))
  52                         return -EFAULT;
  53                 switch (c) {
  54                 case '0':
  55                         gpio_set_value(pin, 0);
  56                         break;
  57                 case '1':
  58                         gpio_set_value(pin, 1);
  59                         break;
  60                 case 'd':
  61                 case 'D':
  62                         ar7_gpio_disable(pin);
  63                         break;
  64                 case 'e':
  65                 case 'E':
  66                         ar7_gpio_enable(pin);
  67                         break;
  68                 case 'i':
  69                 case 'I':
  70                 case '<':
  71                         gpio_direction_input(pin);
  72                         break;
  73                 case 'o':
  74                 case 'O':
  75                 case '>':
  76                         gpio_direction_output(pin);
  77                         break;
  78                 default:
  79                         return -EINVAL;
  80                 }
  81         }
  82
  83         return len;
  84 }
  85
  86 static ssize_t ar7_gpio_read(struct file *file, char __user *buf,
  87         size_t len, loff_t *ppos)
  88 {
  89         int pin = iminor(file->f_dentry->d_inode);
  90         int value;
  91
  92         value = gpio_get_value(pin);
  93         if (put_user(value ? '1' : '0', buf))
  94                 return -EFAULT;
  95
  96         return 1;
  97 }
  98
  99 static int ar7_gpio_open(struct inode *inode, struct file *file)
 100 {
 101         int m = iminor(inode);
 102
 103         if (m >= AR7_GPIO_MAX)
 104                 return -EINVAL;
 105
 106         return nonseekable_open(inode, file);
 107 }
 108
 109 static int ar7_gpio_release(struct inode *inode, struct file *file)
 110 {
 111         return 0;
 112 }
 113
 114 static const struct file_operations ar7_gpio_fops = {
 115         .owner   = THIS_MODULE,
 116         .write   = ar7_gpio_write,
 117         .read    = ar7_gpio_read,
 118         .open    = ar7_gpio_open,
 119         .release = ar7_gpio_release,
 120         .llseek  = no_llseek,
 121 };
 122
 123 static struct platform_device *ar7_gpio_device;
 124
 125 static int __init ar7_gpio_init(void)
 126 {
 127         int rc;
 128
 129         ar7_gpio_device = platform_device_alloc(DRVNAME, -1);
 130         if (!ar7_gpio_device)
 131                 return -ENOMEM;
 132
 133         rc = platform_device_add(ar7_gpio_device);
 134         if (rc < 0)
 135                 goto out_put;
 136
 137         rc = register_chrdev(ar7_gpio_major, DRVNAME, &ar7_gpio_fops);
 138         if (rc < 0)
 139                 goto out_put;
 140
 141         ar7_gpio_major = rc;
 142
 143         rc = 0;
 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);