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}
133