drivers/acpi/ec_sys.c

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