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

   1 /*
   2  * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
   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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18
  19 #include <linux/device.h>
  20 #include <linux/fs.h>
  21 #include <linux/module.h>
  22 #include <linux/errno.h>
  23 #include <linux/kernel.h>
  24 #include <linux/init.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/io.h>
  28 #include <linux/types.h>
  29 #include <linux/cdev.h>
  30 #include <gpio.h>
  31
  32 #define DRVNAME "ar7_gpio"
  33 #define LONGNAME "TI AR7 GPIOs Driver"
  34
  35 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  36 MODULE_DESCRIPTION(LONGNAME);
  37 MODULE_LICENSE("GPL");
  38
  39 static int ar7_gpio_major;
  40
  41 static ssize_t ar7_gpio_write(struct file *file, const char __user *buf,
  42         size_t len, loff_t *ppos)
  43 {
  44         int pin = iminor(file->f_dentry->d_inode);
  45         size_t i;
  46
  47         for (i = 0; i < len; ++i) {
  48                 char c;
  49                 if (get_user(c, buf + i))
  50                         return -EFAULT;
  51                 switch (c) {
  52                 case '0':
  53                         gpio_set_value(pin, 0);
  54                         break;
  55                 case '1':
  56                         gpio_set_value(pin, 1);
  57                         break;
  58                 case 'd':
  59                 case 'D':
  60                         ar7_gpio_disable(pin);
  61                         break;
  62                 case 'e':
  63                 case 'E':
  64                         ar7_gpio_enable(pin);
  65                         break;
  66                 case 'i':
  67                 case 'I':
  68                 case '<':
  69                         gpio_direction_input(pin);
  70                         break;
  71                 case 'o':
  72                 case 'O':
  73                 case '>':
  74                         gpio_direction_output(pin, 0);
  75                         break;
  76                 default:
  77                         return -EINVAL;
  78                 }
  79         }
  80
  81         return len;
  82 }
  83
  84 static ssize_t ar7_gpio_read(struct file *file, char __user *buf,
  85         size_t len, loff_t *ppos)
  86 {
  87         int pin = iminor(file->f_dentry->d_inode);
  88         int value;
  89
  90         value = gpio_get_value(pin);
  91         if (put_user(value ? '1' : '0', buf))
  92                 return -EFAULT;
  93
  94         return 1;
  95 }
  96
  97 static int ar7_gpio_open(struct inode *inode, struct file *file)
  98 {
  99         int m = iminor(inode);
 100
 101         if (m >= AR7_GPIO_MAX)
 102                 return -EINVAL;
 103
 104         return nonseekable_open(inode, file);
 105 }
 106
 107 static int ar7_gpio_release(struct inode *inode, struct file *file)
 108 {
 109         return 0;
 110 }
 111
 112 static const struct file_operations ar7_gpio_fops = {
 113         .owner   = THIS_MODULE,
 114         .write   = ar7_gpio_write,
 115         .read    = ar7_gpio_read,
 116         .open    = ar7_gpio_open,
 117         .release = ar7_gpio_release,
 118         .llseek  = no_llseek,
 119 };
 120
 121 static struct platform_device *ar7_gpio_device;
 122
 123 static int __init ar7_gpio_init(void)
 124 {
 125         int rc;
 126
 127         ar7_gpio_device = platform_device_alloc(DRVNAME, -1);
 128         if (!ar7_gpio_device)
 129                 return -ENOMEM;
 130
 131         rc = platform_device_add(ar7_gpio_device);
 132         if (rc < 0)
 133                 goto out_put;
 134
 135         rc = register_chrdev(ar7_gpio_major, DRVNAME, &ar7_gpio_fops);
 136         if (rc < 0)
 137                 goto out_put;
 138
 139         ar7_gpio_major = rc;
 140
 141         rc = 0;
 142
 143         goto out;
 144
 145 out_put:
 146         platform_device_put(ar7_gpio_device);
 147 out:
 148         return rc;
 149 }
 150
 151 static void __exit ar7_gpio_exit(void)
 152 {
 153         unregister_chrdev(ar7_gpio_major, DRVNAME);
 154         platform_device_unregister(ar7_gpio_device);
 155 }
 156
 157 module_init(ar7_gpio_init);
 158 module_exit(ar7_gpio_exit);