surestart-attributes.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Functions corresponding to sure start object type attributes under
  4 * BIOS for use with hp-bioscfg driver
  5 *
  6 * Copyright (c) 2022 HP Development Company, L.P.
  7 */
  8
  9#include "bioscfg.h"
 10#include <linux/types.h>
 11
 12/* Maximum number of log entries supported when log entry size is 16
 13 * bytes. This value is calculated by dividing 4096 (page size) by
 14 * log entry size.
 15 */
 16#define LOG_MAX_ENTRIES		254
 17
 18/*
 19 * Current Log entry size. This value size will change in the
 20 * future. The driver reads a total of 128 bytes for each log entry
 21 * provided by BIOS but only the first 16 bytes are used/read.
 22 */
 23#define LOG_ENTRY_SIZE		16
 24
 25/*
 26 * audit_log_entry_count_show - Reports the number of
 27 *				existing audit log entries available
 28 *				to be read
 29 */
 30static ssize_t audit_log_entry_count_show(struct kobject *kobj,
 31					  struct kobj_attribute *attr, char *buf)
 32{
 33	int ret;
 34	u32 count = 0;
 35
 36	ret = hp_wmi_perform_query(HPWMI_SURESTART_GET_LOG_COUNT,
 37				   HPWMI_SURESTART,
 38				   &count, 1, sizeof(count));
 39
 40	if (ret < 0)
 41		return ret;
 42
 43	return sysfs_emit(buf, "%d,%d,%d\n", count, LOG_ENTRY_SIZE,
 44			  LOG_MAX_ENTRIES);
 45}
 46
 47/*
 48 * audit_log_entries_show() - Return all entries found in log file
 49 */
 50static ssize_t audit_log_entries_show(struct kobject *kobj,
 51				      struct kobj_attribute *attr, char *buf)
 52{
 53	int ret;
 54	int i;
 55	u32 count = 0;
 56	u8 audit_log_buffer[128];
 57
 58	// Get the number of event logs
 59	ret = hp_wmi_perform_query(HPWMI_SURESTART_GET_LOG_COUNT,
 60				   HPWMI_SURESTART,
 61				   &count, 1, sizeof(count));
 62
 63	if (ret < 0)
 64		return ret;
 65
 66	/*
 67	 * The show() api will not work if the audit logs ever go
 68	 * beyond 4KB
 69	 */
 70	if (count * LOG_ENTRY_SIZE > PAGE_SIZE)
 71		return -EIO;
 72
 73	/*
 74	 * We are guaranteed the buffer is 4KB so today all the event
 75	 * logs will fit
 76	 */
 77	for (i = 0; i < count; i++) {
 78		audit_log_buffer[0] = i + 1;
 79
 80		/*
 81		 * read audit log entry at a time. 'buf' input value
 82		 * provides the audit log entry to be read. On
 83		 * input, Byte 0 = Audit Log entry number from
 84		 * beginning (1..254)
 85		 * Entry number 1 is the newest entry whereas the
 86		 * highest entry number (number of entries) is the
 87		 * oldest entry.
 88		 */
 89		ret = hp_wmi_perform_query(HPWMI_SURESTART_GET_LOG,
 90					   HPWMI_SURESTART,
 91					   audit_log_buffer, 1, 128);
 92
 93		if (ret < 0 || (LOG_ENTRY_SIZE * i) > PAGE_SIZE) {
 94			/*
 95			 * Encountered a failure while reading
 96			 * individual logs. Only a partial list of
 97			 * audit log will be returned.
 98			 */
 99			break;
100		} else {
101			memcpy(buf, audit_log_buffer, LOG_ENTRY_SIZE);
102			buf += LOG_ENTRY_SIZE;
103		}
104	}
105
106	return i * LOG_ENTRY_SIZE;
107}
108
109static struct kobj_attribute sure_start_audit_log_entry_count = __ATTR_RO(audit_log_entry_count);
110static struct kobj_attribute sure_start_audit_log_entries = __ATTR_RO(audit_log_entries);
111
112static struct attribute *sure_start_attrs[] = {
113	&sure_start_audit_log_entry_count.attr,
114	&sure_start_audit_log_entries.attr,
115	NULL
116};
117
118static const struct attribute_group sure_start_attr_group = {
119	.attrs = sure_start_attrs,
120};
121
122void hp_exit_sure_start_attributes(void)
123{
124	sysfs_remove_group(bioscfg_drv.sure_start_attr_kobj,
125			   &sure_start_attr_group);
126}
127
128int hp_populate_sure_start_data(struct kobject *attr_name_kobj)
129{
130	bioscfg_drv.sure_start_attr_kobj = attr_name_kobj;
131	return sysfs_create_group(attr_name_kobj, &sure_start_attr_group);
132}