drivers/firmware/google/memconsole.c

   1 /*
   2  * memconsole.c
   3  *
   4  * Architecture-independent parts of the memory based BIOS console.
   5  *
   6  * Copyright 2017 Google Inc.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License v2.0 as published by
  10  * the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #include <linux/init.h>
  19 #include <linux/sysfs.h>
  20 #include <linux/kobject.h>
  21 #include <linux/module.h>
  22
  23 #include "memconsole.h"
  24
  25 static ssize_t (*memconsole_read_func)(char *, loff_t, size_t);
  26
  27 static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
  28                                struct bin_attribute *bin_attr, char *buf,
  29                                loff_t pos, size_t count)
  30 {
  31         if (WARN_ON_ONCE(!memconsole_read_func))
  32                 return -EIO;
  33         return memconsole_read_func(buf, pos, count);
  34 }
  35
  36 static struct bin_attribute memconsole_bin_attr = {
  37         .attr = {.name = "log", .mode = 0444},
  38         .read = memconsole_read,
  39 };
  40
  41 void memconsole_setup(ssize_t (*read_func)(char *, loff_t, size_t))
  42 {
  43         memconsole_read_func = read_func;
  44 }
  45 EXPORT_SYMBOL(memconsole_setup);
  46
  47 int memconsole_sysfs_init(void)
  48 {
  49         return sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
  50 }
  51 EXPORT_SYMBOL(memconsole_sysfs_init);
  52
  53 void memconsole_exit(void)
  54 {
  55         sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
  56 }
  57 EXPORT_SYMBOL(memconsole_exit);
  58
  59 MODULE_AUTHOR("Google, Inc.");
  60 MODULE_LICENSE("GPL");