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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * SMI methods for use with dell-smbios
4 *
5 * Copyright (c) Red Hat <mjg@redhat.com>
6 * Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
7 * Copyright (c) 2014 Pali Rohár <pali@kernel.org>
8 * Copyright (c) 2017 Dell Inc.
9 */
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/dmi.h>
13#include <linux/gfp.h>
14#include <linux/io.h>
15#include <linux/module.h>
16#include <linux/mutex.h>
17#include <linux/platform_device.h>
18#include "dcdbas.h"
19#include "dell-smbios.h"
20
21static int da_command_address;
22static int da_command_code;
23static struct smi_buffer smi_buf;
24static struct calling_interface_buffer *buffer;
25static struct platform_device *platform_device;
26static DEFINE_MUTEX(smm_mutex);
27
28static void parse_da_table(const struct dmi_header *dm)
29{
30 struct calling_interface_structure *table =
31 container_of(dm, struct calling_interface_structure, header);
32
33 /* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
34 * 6 bytes of entry
35 */
36 if (dm->length < 17)
37 return;
38
39 da_command_address = table->cmdIOAddress;
40 da_command_code = table->cmdIOCode;
41}
42
43static void find_cmd_address(const struct dmi_header *dm, void *dummy)
44{
45 switch (dm->type) {
46 case 0xda: /* Calling interface */
47 parse_da_table(dm);
48 break;
49 }
50}
51
52static int dell_smbios_smm_call(struct calling_interface_buffer *input)
53{
54 struct smi_cmd command;
55 size_t size;
56
57 size = sizeof(struct calling_interface_buffer);
58 command.magic = SMI_CMD_MAGIC;
59 command.command_address = da_command_address;
60 command.command_code = da_command_code;
61 command.ebx = smi_buf.dma;
62 command.ecx = 0x42534931;
63
64 mutex_lock(&smm_mutex);
65 memcpy(buffer, input, size);
66 dcdbas_smi_request(&command);
67 memcpy(input, buffer, size);
68 mutex_unlock(&smm_mutex);
69 return 0;
70}
71
72/* When enabled this indicates that SMM won't work */
73static bool test_wsmt_enabled(void)
74{
75 struct calling_interface_token *wsmt;
76
77 /* if token doesn't exist, SMM will work */
78 wsmt = dell_smbios_find_token(WSMT_EN_TOKEN);
79 if (!wsmt)
80 return false;
81
82 /* If token exists, try to access over SMM but set a dummy return.
83 * - If WSMT disabled it will be overwritten by SMM
84 * - If WSMT enabled then dummy value will remain
85 */
86 buffer->cmd_class = CLASS_TOKEN_READ;
87 buffer->cmd_select = SELECT_TOKEN_STD;
88 memset(buffer, 0, sizeof(struct calling_interface_buffer));
89 buffer->input[0] = wsmt->location;
90 buffer->output[0] = 99;
91 dell_smbios_smm_call(buffer);
92 if (buffer->output[0] == 99)
93 return true;
94
95 return false;
96}
97
98int init_dell_smbios_smm(void)
99{
100 int ret;
101 /*
102 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
103 * is passed to SMI handler.
104 */
105 ret = dcdbas_smi_alloc(&smi_buf, PAGE_SIZE);
106 if (ret)
107 return ret;
108 buffer = (void *)smi_buf.virt;
109
110 dmi_walk(find_cmd_address, NULL);
111
112 if (test_wsmt_enabled()) {
113 pr_debug("Disabling due to WSMT enabled\n");
114 ret = -ENODEV;
115 goto fail_wsmt;
116 }
117
118 platform_device = platform_device_alloc("dell-smbios", 1);
119 if (!platform_device) {
120 ret = -ENOMEM;
121 goto fail_platform_device_alloc;
122 }
123
124 ret = platform_device_add(platform_device);
125 if (ret)
126 goto fail_platform_device_add;
127
128 ret = dell_smbios_register_device(&platform_device->dev,
129 &dell_smbios_smm_call);
130 if (ret)
131 goto fail_register;
132
133 return 0;
134
135fail_register:
136 platform_device_del(platform_device);
137
138fail_platform_device_add:
139 platform_device_put(platform_device);
140
141fail_wsmt:
142fail_platform_device_alloc:
143 dcdbas_smi_free(&smi_buf);
144 return ret;
145}
146
147void exit_dell_smbios_smm(void)
148{
149 if (platform_device) {
150 dell_smbios_unregister_device(&platform_device->dev);
151 platform_device_unregister(platform_device);
152 dcdbas_smi_free(&smi_buf);
153 }
154}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * SMI methods for use with dell-smbios
4 *
5 * Copyright (c) Red Hat <mjg@redhat.com>
6 * Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
7 * Copyright (c) 2014 Pali Rohár <pali@kernel.org>
8 * Copyright (c) 2017 Dell Inc.
9 */
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/dmi.h>
13#include <linux/gfp.h>
14#include <linux/io.h>
15#include <linux/module.h>
16#include <linux/mutex.h>
17#include <linux/platform_device.h>
18#include "dcdbas.h"
19#include "dell-smbios.h"
20
21static int da_command_address;
22static int da_command_code;
23static struct calling_interface_buffer *buffer;
24static struct platform_device *platform_device;
25static DEFINE_MUTEX(smm_mutex);
26
27static const struct dmi_system_id dell_device_table[] __initconst = {
28 {
29 .ident = "Dell laptop",
30 .matches = {
31 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
32 DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
33 },
34 },
35 {
36 .matches = {
37 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
38 DMI_MATCH(DMI_CHASSIS_TYPE, "9"), /*Laptop*/
39 },
40 },
41 {
42 .matches = {
43 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
44 DMI_MATCH(DMI_CHASSIS_TYPE, "10"), /*Notebook*/
45 },
46 },
47 {
48 .ident = "Dell Computer Corporation",
49 .matches = {
50 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
51 DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
52 },
53 },
54 { }
55};
56MODULE_DEVICE_TABLE(dmi, dell_device_table);
57
58static void parse_da_table(const struct dmi_header *dm)
59{
60 struct calling_interface_structure *table =
61 container_of(dm, struct calling_interface_structure, header);
62
63 /* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
64 * 6 bytes of entry
65 */
66 if (dm->length < 17)
67 return;
68
69 da_command_address = table->cmdIOAddress;
70 da_command_code = table->cmdIOCode;
71}
72
73static void find_cmd_address(const struct dmi_header *dm, void *dummy)
74{
75 switch (dm->type) {
76 case 0xda: /* Calling interface */
77 parse_da_table(dm);
78 break;
79 }
80}
81
82static int dell_smbios_smm_call(struct calling_interface_buffer *input)
83{
84 struct smi_cmd command;
85 size_t size;
86
87 size = sizeof(struct calling_interface_buffer);
88 command.magic = SMI_CMD_MAGIC;
89 command.command_address = da_command_address;
90 command.command_code = da_command_code;
91 command.ebx = virt_to_phys(buffer);
92 command.ecx = 0x42534931;
93
94 mutex_lock(&smm_mutex);
95 memcpy(buffer, input, size);
96 dcdbas_smi_request(&command);
97 memcpy(input, buffer, size);
98 mutex_unlock(&smm_mutex);
99 return 0;
100}
101
102/* When enabled this indicates that SMM won't work */
103static bool test_wsmt_enabled(void)
104{
105 struct calling_interface_token *wsmt;
106
107 /* if token doesn't exist, SMM will work */
108 wsmt = dell_smbios_find_token(WSMT_EN_TOKEN);
109 if (!wsmt)
110 return false;
111
112 /* If token exists, try to access over SMM but set a dummy return.
113 * - If WSMT disabled it will be overwritten by SMM
114 * - If WSMT enabled then dummy value will remain
115 */
116 buffer->cmd_class = CLASS_TOKEN_READ;
117 buffer->cmd_select = SELECT_TOKEN_STD;
118 memset(buffer, 0, sizeof(struct calling_interface_buffer));
119 buffer->input[0] = wsmt->location;
120 buffer->output[0] = 99;
121 dell_smbios_smm_call(buffer);
122 if (buffer->output[0] == 99)
123 return true;
124
125 return false;
126}
127
128int init_dell_smbios_smm(void)
129{
130 int ret;
131 /*
132 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
133 * is passed to SMI handler.
134 */
135 buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
136 if (!buffer)
137 return -ENOMEM;
138
139 dmi_walk(find_cmd_address, NULL);
140
141 if (test_wsmt_enabled()) {
142 pr_debug("Disabling due to WSMT enabled\n");
143 ret = -ENODEV;
144 goto fail_wsmt;
145 }
146
147 platform_device = platform_device_alloc("dell-smbios", 1);
148 if (!platform_device) {
149 ret = -ENOMEM;
150 goto fail_platform_device_alloc;
151 }
152
153 ret = platform_device_add(platform_device);
154 if (ret)
155 goto fail_platform_device_add;
156
157 ret = dell_smbios_register_device(&platform_device->dev,
158 &dell_smbios_smm_call);
159 if (ret)
160 goto fail_register;
161
162 return 0;
163
164fail_register:
165 platform_device_del(platform_device);
166
167fail_platform_device_add:
168 platform_device_put(platform_device);
169
170fail_wsmt:
171fail_platform_device_alloc:
172 free_page((unsigned long)buffer);
173 return ret;
174}
175
176void exit_dell_smbios_smm(void)
177{
178 if (platform_device) {
179 dell_smbios_unregister_device(&platform_device->dev);
180 platform_device_unregister(platform_device);
181 free_page((unsigned long)buffer);
182 }
183}