diff options
Diffstat (limited to 'drivers/platform/x86/dell-smbios-smm.c')
| -rw-r--r-- | drivers/platform/x86/dell-smbios-smm.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/drivers/platform/x86/dell-smbios-smm.c b/drivers/platform/x86/dell-smbios-smm.c new file mode 100644 index 000000000..97a90bebc --- /dev/null +++ b/drivers/platform/x86/dell-smbios-smm.c @@ -0,0 +1,186 @@ +/* + * SMI methods for use with dell-smbios + * + * Copyright (c) Red Hat <mjg@redhat.com> + * Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com> + * Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com> + * Copyright (c) 2017 Dell Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/dmi.h> +#include <linux/gfp.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/platform_device.h> +#include "../../firmware/dcdbas.h" +#include "dell-smbios.h" + +static int da_command_address; +static int da_command_code; +static struct calling_interface_buffer *buffer; +static struct platform_device *platform_device; +static DEFINE_MUTEX(smm_mutex); + +static const struct dmi_system_id dell_device_table[] __initconst = { + { + .ident = "Dell laptop", + .matches = { + DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), + DMI_MATCH(DMI_CHASSIS_TYPE, "8"), + }, + }, + { + .matches = { + DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), + DMI_MATCH(DMI_CHASSIS_TYPE, "9"), /*Laptop*/ + }, + }, + { + .matches = { + DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), + DMI_MATCH(DMI_CHASSIS_TYPE, "10"), /*Notebook*/ + }, + }, + { + .ident = "Dell Computer Corporation", + .matches = { + DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"), + DMI_MATCH(DMI_CHASSIS_TYPE, "8"), + }, + }, + { } +}; +MODULE_DEVICE_TABLE(dmi, dell_device_table); + +static void parse_da_table(const struct dmi_header *dm) +{ + struct calling_interface_structure *table = + container_of(dm, struct calling_interface_structure, header); + + /* 4 bytes of table header, plus 7 bytes of Dell header, plus at least + * 6 bytes of entry + */ + if (dm->length < 17) + return; + + da_command_address = table->cmdIOAddress; + da_command_code = table->cmdIOCode; +} + +static void find_cmd_address(const struct dmi_header *dm, void *dummy) +{ + switch (dm->type) { + case 0xda: /* Calling interface */ + parse_da_table(dm); + break; + } +} + +static int dell_smbios_smm_call(struct calling_interface_buffer *input) +{ + struct smi_cmd command; + size_t size; + + size = sizeof(struct calling_interface_buffer); + command.magic = SMI_CMD_MAGIC; + command.command_address = da_command_address; + command.command_code = da_command_code; + command.ebx = virt_to_phys(buffer); + command.ecx = 0x42534931; + + mutex_lock(&smm_mutex); + memcpy(buffer, input, size); + dcdbas_smi_request(&command); + memcpy(input, buffer, size); + mutex_unlock(&smm_mutex); + return 0; +} + +/* When enabled this indicates that SMM won't work */ +static bool test_wsmt_enabled(void) +{ + struct calling_interface_token *wsmt; + + /* if token doesn't exist, SMM will work */ + wsmt = dell_smbios_find_token(WSMT_EN_TOKEN); + if (!wsmt) + return false; + + /* If token exists, try to access over SMM but set a dummy return. + * - If WSMT disabled it will be overwritten by SMM + * - If WSMT enabled then dummy value will remain + */ + buffer->cmd_class = CLASS_TOKEN_READ; + buffer->cmd_select = SELECT_TOKEN_STD; + memset(buffer, 0, sizeof(struct calling_interface_buffer)); + buffer->input[0] = wsmt->location; + buffer->output[0] = 99; + dell_smbios_smm_call(buffer); + if (buffer->output[0] == 99) + return true; + + return false; +} + +int init_dell_smbios_smm(void) +{ + int ret; + /* + * Allocate buffer below 4GB for SMI data--only 32-bit physical addr + * is passed to SMI handler. + */ + buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32); + if (!buffer) + return -ENOMEM; + + dmi_walk(find_cmd_address, NULL); + + if (test_wsmt_enabled()) { + pr_debug("Disabling due to WSMT enabled\n"); + ret = -ENODEV; + goto fail_wsmt; + } + + platform_device = platform_device_alloc("dell-smbios", 1); + if (!platform_device) { + ret = -ENOMEM; + goto fail_platform_device_alloc; + } + + ret = platform_device_add(platform_device); + if (ret) + goto fail_platform_device_add; + + ret = dell_smbios_register_device(&platform_device->dev, + &dell_smbios_smm_call); + if (ret) + goto fail_register; + + return 0; + +fail_register: + platform_device_del(platform_device); + +fail_platform_device_add: + platform_device_put(platform_device); + +fail_wsmt: +fail_platform_device_alloc: + free_page((unsigned long)buffer); + return ret; +} + +void exit_dell_smbios_smm(void) +{ + if (platform_device) { + dell_smbios_unregister_device(&platform_device->dev); + platform_device_unregister(platform_device); + free_page((unsigned long)buffer); + } +} |