LXR linux/drivers/acpi/ec

   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
  18MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>");
  19MODULE_DESCRIPTION("ACPI EC sysfs access driver");
  20MODULE_LICENSE("GPL");
  21
  22static bool write_support;
  23module_param(write_support, bool, 0644);
  24MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may "
  25                 "be needed.");
  26
  27#define EC_SPACE_SIZE 256
  28
  29static struct dentry *acpi_ec_debugfs_dir;
  30
  31static 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
  65static 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
 103static 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
 111static 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
 132static 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
 139static void __exit acpi_ec_sys_exit(void)
 140{
 141        debugfs_remove_recursive(acpi_ec_debugfs_dir);
 142}
 143
 144module_init(acpi_ec_sys_init);
 145module_exit(acpi_ec_sys_exit);
 146