linux/drivers/acpi/ec_sys.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * ec_sys.c
   4 *
   5 * Copyright (C) 2010 SUSE Products GmbH/Novell
   6 * Author:
   7 *      Thomas Renninger <trenn@suse.de>
   8 */
   9
  10#include <linux/kernel.h>
  11#include <linux/acpi.h>
  12#include <linux/debugfs.h>
  13#include <linux/module.h>
  14#include <linux/uaccess.h>
  15#include "internal.h"
  16
  17MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>");
  18MODULE_DESCRIPTION("ACPI EC sysfs access driver");
  19MODULE_LICENSE("GPL");
  20
  21static bool write_support;
  22module_param(write_support, bool, 0644);
  23MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may "
  24                 "be needed.");
  25
  26#define EC_SPACE_SIZE 256
  27
  28static struct dentry *acpi_ec_debugfs_dir;
  29
  30static ssize_t acpi_ec_read_io(struct file *f, char __user *buf,
  31                               size_t count, loff_t *off)
  32{
  33        /* Use this if support reading/writing multiple ECs exists in ec.c:
  34         * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
  35         */
  36        unsigned int size = EC_SPACE_SIZE;
  37        loff_t init_off = *off;
  38        int err = 0;
  39
  40        if (*off >= size)
  41                return 0;
  42        if (*off + count >= size) {
  43                size -= *off;
  44                count = size;
  45        } else
  46                size = count;
  47
  48        while (size) {
  49                u8 byte_read;
  50                err = ec_read(*off, &byte_read);
  51                if (err)
  52                        return err;
  53                if (put_user(byte_read, buf + *off - init_off)) {
  54                        if (*off - init_off)
  55                                return *off - init_off; /* partial read */
  56                        return -EFAULT;
  57                }
  58                *off += 1;
  59                size--;
  60        }
  61        return count;
  62}
  63
  64static ssize_t acpi_ec_write_io(struct file *f, const char __user *buf,
  65                                size_t count, loff_t *off)
  66{
  67        /* Use this if support reading/writing multiple ECs exists in ec.c:
  68         * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
  69         */
  70
  71        unsigned int size = count;
  72        loff_t init_off = *off;
  73        int err = 0;
  74
  75        if (!write_support)
  76                return -EINVAL;
  77
  78        if (*off >= EC_SPACE_SIZE)
  79                return 0;
  80        if (*off + count >= EC_SPACE_SIZE) {
  81                size = EC_SPACE_SIZE - *off;
  82                count = size;
  83        }
  84
  85        while (size) {
  86                u8 byte_write;
  87                if (get_user(byte_write, buf + *off - init_off)) {
  88                        if (*off - init_off)
  89                                return *off - init_off; /* partial write */
  90                        return -EFAULT;
  91                }
  92                err = ec_write(*off, byte_write);
  93                if (err)
  94                        return err;
  95
  96                *off += 1;
  97                size--;
  98        }
  99        return count;
 100}
 101
 102static const struct file_operations acpi_ec_io_ops = {
 103        .owner = THIS_MODULE,
 104        .open  = simple_open,
 105        .read  = acpi_ec_read_io,
 106        .write = acpi_ec_write_io,
 107        .llseek = default_llseek,
 108};
 109
 110static void acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count)
 111{
 112        struct dentry *dev_dir;
 113        char name[64];
 114        umode_t mode = 0400;
 115
 116        if (ec_device_count == 0)
 117                acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);
 118
 119        sprintf(name, "ec%u", ec_device_count);
 120        dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir);
 121
 122        debugfs_create_x32("gpe", 0444, dev_dir, &first_ec->gpe);
 123        debugfs_create_bool("use_global_lock", 0444, dev_dir,
 124                            &first_ec->global_lock);
 125
 126        if (write_support)
 127                mode = 0600;
 128        debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops);
 129}
 130
 131static int __init acpi_ec_sys_init(void)
 132{
 133        if (first_ec)
 134                acpi_ec_add_debugfs(first_ec, 0);
 135        return 0;
 136}
 137
 138static void __exit acpi_ec_sys_exit(void)
 139{
 140        debugfs_remove_recursive(acpi_ec_debugfs_dir);
 141}
 142
 143module_init(acpi_ec_sys_init);
 144module_exit(acpi_ec_sys_exit);
 145