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/sysfs.h>
  11 #include <linux/kobject.h>
  12 #include <linux/module.h>
  13
  14 #include "memconsole.h"
  15
  16 static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
  17                                struct bin_attribute *bin_attr, char *buf,
  18                                loff_t pos, size_t count)
  19 {
  20         ssize_t (*memconsole_read_func)(char *, loff_t, size_t);
  21
  22         memconsole_read_func = bin_attr->private;
  23         if (WARN_ON_ONCE(!memconsole_read_func))
  24                 return -EIO;
  25
  26         return memconsole_read_func(buf, pos, count);
  27 }
  28
  29 static struct bin_attribute memconsole_bin_attr = {
  30         .attr = {.name = "log", .mode = 0444},
  31         .read = memconsole_read,
  32 };
  33
  34 void memconsole_setup(ssize_t (*read_func)(char *, loff_t, size_t))
  35 {
  36         memconsole_bin_attr.private = read_func;
  37 }
  38 EXPORT_SYMBOL(memconsole_setup);
  39
  40 int memconsole_sysfs_init(void)
  41 {
  42         return sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
  43 }
  44 EXPORT_SYMBOL(memconsole_sysfs_init);
  45
  46 void memconsole_exit(void)
  47 {
  48         sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
  49 }
  50 EXPORT_SYMBOL(memconsole_exit);
  51
  52 MODULE_AUTHOR("Google, Inc.");
  53 MODULE_LICENSE("GPL");