kernel/drivers/acpi/ec_sys.c

   1 /*
   2  * ec_sys.c
   3  *
   4  * Copyright (C) 2010 SUSE Products GmbH/Novell
   5  * Author:
   6  *      Thomas Renninger <trenn@suse.de>
   7  *
   8  * This work is licensed under the terms of the GNU GPL, version 2.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/acpi.h>
  13 #include <linux/debugfs.h>
  14 #include <linux/module.h>
  15 #include <linux/uaccess.h>
  16 #include "internal.h"
  17
  18 MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>");
  19 MODULE_DESCRIPTION("ACPI EC sysfs access driver");
  20 MODULE_LICENSE("GPL");
  21
  22 static bool write_support;
  23 module_param(write_support, bool, 0644);
  24 MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may "
  25                  "be needed.");
  26
  27 #define EC_SPACE_SIZE 256
  28
  29 static struct dentry *acpi_ec_debugfs_dir;
  30
  31 static ssize_t acpi_ec_read_io(struct file *f, char __user *buf,
  32                                size_t count, loff_t *off)
  33 {
  34         /* Use this if support reading/writing multiple ECs exists in ec.c:
  35          * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
  36          */
  37         unsigned int size = EC_SPACE_SIZE;
  38         loff_t init_off = *off;
  39         int err = 0;
  40
  41         if (*off >= size)
  42                 return 0;
  43         if (*off + count >= size) {
  44                 size -= *off;
  45                 count = size;
  46         } else
  47                 size = count;
  48
  49         while (size) {
  50                 u8 byte_read;
  51                 err = ec_read(*off, &byte_read);
  52                 if (err)
  53                         return err;
  54                 if (put_user(byte_read, buf + *off - init_off)) {
  55                         if (*off - init_off)
  56                                 return *off - init_off; /* partial read */
  57                         return -EFAULT;
  58                 }
  59                 *off += 1;
  60                 size--;
  61         }
  62         return count;
  63 }
  64
  65 static ssize_t acpi_ec_write_io(struct file *f, const char __user *buf,
  66                                 size_t count, loff_t *off)
  67 {
  68         /* Use this if support reading/writing multiple ECs exists in ec.c:
  69          * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
  70          */
  71
  72         unsigned int size = count;
  73         loff_t init_off = *off;
  74         int err = 0;
  75
  76         if (*off >= EC_SPACE_SIZE)
  77                 return 0;
  78         if (*off + count >= EC_SPACE_SIZE) {
  79                 size = EC_SPACE_SIZE - *off;
  80                 count = size;
  81         }
  82
  83         while (size) {
  84                 u8 byte_write;
  85                 if (get_user(byte_write, buf + *off - init_off)) {
  86                         if (*off - init_off)
  87                                 return *off - init_off; /* partial write */
  88                         return -EFAULT;
  89                 }
  90                 err = ec_write(*off, byte_write);
  91                 if (err)
  92                         return err;
  93
  94                 *off += 1;
  95                 size--;
  96         }
  97         return count;
  98 }
  99
 100 static const struct file_operations acpi_ec_io_ops = {
 101         .owner = THIS_MODULE,
 102         .open  = simple_open,
 103         .read  = acpi_ec_read_io,
 104         .write = acpi_ec_write_io,
 105         .llseek = default_llseek,
 106 };
 107
 108 static int acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count)
 109 {
 110         struct dentry *dev_dir;
 111         char name[64];
 112         umode_t mode = 0400;
 113
 114         if (ec_device_count == 0) {
 115                 acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);
 116                 if (!acpi_ec_debugfs_dir)
 117                         return -ENOMEM;
 118         }
 119
 120         sprintf(name, "ec%u", ec_device_count);
 121         dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir);
 122         if (!dev_dir) {
 123                 if (ec_device_count != 0)
 124                         goto error;
 125                 return -ENOMEM;
 126         }
 127
 128         if (!debugfs_create_x32("gpe", 0444, dev_dir, (u32 *)&first_ec->gpe))
 129                 goto error;
 130         if (!debugfs_create_bool("use_global_lock", 0444, dev_dir,
 131                                  (u32 *)&first_ec->global_lock))
 132                 goto error;
 133
 134         if (write_support)
 135                 mode = 0600;
 136         if (!debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops))
 137                 goto error;
 138
 139         return 0;
 140
 141 error:
 142         debugfs_remove_recursive(acpi_ec_debugfs_dir);
 143         return -ENOMEM;
 144 }
 145
 146 static int __init acpi_ec_sys_init(void)
 147 {
 148         int err = 0;
 149         if (first_ec)
 150                 err = acpi_ec_add_debugfs(first_ec, 0);
 151         else
 152                 err = -ENODEV;
 153         return err;
 154 }
 155
 156 static void __exit acpi_ec_sys_exit(void)
 157 {
 158         debugfs_remove_recursive(acpi_ec_debugfs_dir);
 159 }
 160
 161 module_init(acpi_ec_sys_init);
 162 module_exit(acpi_ec_sys_exit);