linux/drivers/acpi/ec_sys.c
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   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 (*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
 100static 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
 108int 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
 141error:
 142        debugfs_remove_recursive(acpi_ec_debugfs_dir);
 143        return -ENOMEM;
 144}
 145
 146static 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
 156static void __exit acpi_ec_sys_exit(void)
 157{
 158        debugfs_remove_recursive(acpi_ec_debugfs_dir);
 159}
 160
 161module_init(acpi_ec_sys_init);
 162module_exit(acpi_ec_sys_exit);
 163
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