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 (!write_support)
  77                 return -EINVAL;
  78
  79         if (*off >= EC_SPACE_SIZE)
  80                 return 0;
  81         if (*off + count >= EC_SPACE_SIZE) {
  82                 size = EC_SPACE_SIZE - *off;
  83                 count = size;
  84         }
  85
  86         while (size) {
  87                 u8 byte_write;
  88                 if (get_user(byte_write, buf + *off - init_off)) {
  89                         if (*off - init_off)
  90                                 return *off - init_off; /* partial write */
  91                         return -EFAULT;
  92                 }
  93                 err = ec_write(*off, byte_write);
  94                 if (err)
  95                         return err;
  96
  97                 *off += 1;
  98                 size--;
  99         }
 100         return count;
 101 }
 102
 103 static const struct file_operations acpi_ec_io_ops = {
 104         .owner = THIS_MODULE,
 105         .open  = simple_open,
 106         .read  = acpi_ec_read_io,
 107         .write = acpi_ec_write_io,
 108         .llseek = default_llseek,
 109 };
 110
 111 static void acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count)
 112 {
 113         struct dentry *dev_dir;
 114         char name[64];
 115         umode_t mode = 0400;
 116
 117         if (ec_device_count == 0)
 118                 acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);
 119
 120         sprintf(name, "ec%u", ec_device_count);
 121         dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir);
 122
 123         debugfs_create_x32("gpe", 0444, dev_dir, &first_ec->gpe);
 124         debugfs_create_bool("use_global_lock", 0444, dev_dir,
 125                             &first_ec->global_lock);
 126
 127         if (write_support)
 128                 mode = 0600;
 129         debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops);
 130 }
 131
 132 static int __init acpi_ec_sys_init(void)
 133 {
 134         if (first_ec)
 135                 acpi_ec_add_debugfs(first_ec, 0);
 136         return 0;
 137 }
 138
 139 static void __exit acpi_ec_sys_exit(void)
 140 {
 141         debugfs_remove_recursive(acpi_ec_debugfs_dir);
 142 }
 143
 144 module_init(acpi_ec_sys_init);
 145 module_exit(acpi_ec_sys_exit);