WIP FPC-III support
[linux/fpc-iii.git] / drivers / platform / x86 / dell-smbios-smm.c
blob97c52a839a3e2671cda43960495772e5b10d4b60
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * SMI methods for use with dell-smbios
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
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"
21 static int da_command_address;
22 static int da_command_code;
23 static struct calling_interface_buffer *buffer;
24 static struct platform_device *platform_device;
25 static DEFINE_MUTEX(smm_mutex);
27 static const struct dmi_system_id dell_device_table[] __initconst = {
29 .ident = "Dell laptop",
30 .matches = {
31 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
32 DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
36 .matches = {
37 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
38 DMI_MATCH(DMI_CHASSIS_TYPE, "9"), /*Laptop*/
42 .matches = {
43 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
44 DMI_MATCH(DMI_CHASSIS_TYPE, "10"), /*Notebook*/
48 .ident = "Dell Computer Corporation",
49 .matches = {
50 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
51 DMI_MATCH(DMI_CHASSIS_TYPE, "8"),
54 { }
56 MODULE_DEVICE_TABLE(dmi, dell_device_table);
58 static void parse_da_table(const struct dmi_header *dm)
60 struct calling_interface_structure *table =
61 container_of(dm, struct calling_interface_structure, header);
63 /* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
64 * 6 bytes of entry
66 if (dm->length < 17)
67 return;
69 da_command_address = table->cmdIOAddress;
70 da_command_code = table->cmdIOCode;
73 static void find_cmd_address(const struct dmi_header *dm, void *dummy)
75 switch (dm->type) {
76 case 0xda: /* Calling interface */
77 parse_da_table(dm);
78 break;
82 static int dell_smbios_smm_call(struct calling_interface_buffer *input)
84 struct smi_cmd command;
85 size_t size;
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;
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;
102 /* When enabled this indicates that SMM won't work */
103 static bool test_wsmt_enabled(void)
105 struct calling_interface_token *wsmt;
107 /* if token doesn't exist, SMM will work */
108 wsmt = dell_smbios_find_token(WSMT_EN_TOKEN);
109 if (!wsmt)
110 return false;
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
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;
125 return false;
128 int init_dell_smbios_smm(void)
130 int ret;
132 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
133 * is passed to SMI handler.
135 buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
136 if (!buffer)
137 return -ENOMEM;
139 dmi_walk(find_cmd_address, NULL);
141 if (test_wsmt_enabled()) {
142 pr_debug("Disabling due to WSMT enabled\n");
143 ret = -ENODEV;
144 goto fail_wsmt;
147 platform_device = platform_device_alloc("dell-smbios", 1);
148 if (!platform_device) {
149 ret = -ENOMEM;
150 goto fail_platform_device_alloc;
153 ret = platform_device_add(platform_device);
154 if (ret)
155 goto fail_platform_device_add;
157 ret = dell_smbios_register_device(&platform_device->dev,
158 &dell_smbios_smm_call);
159 if (ret)
160 goto fail_register;
162 return 0;
164 fail_register:
165 platform_device_del(platform_device);
167 fail_platform_device_add:
168 platform_device_put(platform_device);
170 fail_wsmt:
171 fail_platform_device_alloc:
172 free_page((unsigned long)buffer);
173 return ret;
176 void exit_dell_smbios_smm(void)
178 if (platform_device) {
179 dell_smbios_unregister_device(&platform_device->dev);
180 platform_device_unregister(platform_device);
181 free_page((unsigned long)buffer);