drivers/firmware/google/memconsole.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * memconsole.c
   4  *
   5  * Architecture-independent parts of the memory based BIOS console.
   6  *
   7  * Copyright 2017 Google Inc.
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/sysfs.h>
  12 #include <linux/kobject.h>
  13 #include <linux/module.h>
  14
  15 #include "memconsole.h"
  16
  17 static ssize_t (*memconsole_read_func)(char *, loff_t, size_t);
  18
  19 static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
  20                                struct bin_attribute *bin_attr, char *buf,
  21                                loff_t pos, size_t count)
  22 {
  23         if (WARN_ON_ONCE(!memconsole_read_func))
  24                 return -EIO;
  25         return memconsole_read_func(buf, pos, count);
  26 }
  27
  28 static struct bin_attribute memconsole_bin_attr = {
  29         .attr = {.name = "log", .mode = 0444},
  30         .read = memconsole_read,
  31 };
  32
  33 void memconsole_setup(ssize_t (*read_func)(char *, loff_t, size_t))
  34 {
  35         memconsole_read_func = read_func;
  36 }
  37 EXPORT_SYMBOL(memconsole_setup);
  38
  39 int memconsole_sysfs_init(void)
  40 {
  41         return sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
  42 }
  43 EXPORT_SYMBOL(memconsole_sysfs_init);
  44
  45 void memconsole_exit(void)
  46 {
  47         sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
  48 }
  49 EXPORT_SYMBOL(memconsole_exit);
  50
  51 MODULE_AUTHOR("Google, Inc.");
  52 MODULE_LICENSE("GPL");