firmware: dcdbas: Add support for WSMT ACPI table
If the WSMT ACPI table is present and indicates that a fixed communication buffer should be used, use the firmware-specified buffer instead of allocating a buffer in memory for communications between the dcdbas driver and firmare. Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Stuart Hayes
Andy Shevchenko
parent
6aecee6ad4
commit
12c956c4f3
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@ -21,6 +21,7 @@
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*/
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#include <linux/platform_device.h>
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#include <linux/acpi.h>
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#include <linux/dma-mapping.h>
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#include <linux/errno.h>
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#include <linux/cpu.h>
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@ -41,7 +42,7 @@
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#include "dcdbas.h"
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#define DRIVER_NAME "dcdbas"
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#define DRIVER_VERSION "5.6.0-3.2"
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#define DRIVER_VERSION "5.6.0-3.3"
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#define DRIVER_DESCRIPTION "Dell Systems Management Base Driver"
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static struct platform_device *dcdbas_pdev;
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@ -49,19 +50,23 @@ static struct platform_device *dcdbas_pdev;
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static u8 *smi_data_buf;
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static dma_addr_t smi_data_buf_handle;
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static unsigned long smi_data_buf_size;
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static unsigned long max_smi_data_buf_size = MAX_SMI_DATA_BUF_SIZE;
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static u32 smi_data_buf_phys_addr;
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static DEFINE_MUTEX(smi_data_lock);
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static u8 *eps_buffer;
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static unsigned int host_control_action;
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static unsigned int host_control_smi_type;
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static unsigned int host_control_on_shutdown;
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static bool wsmt_enabled;
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/**
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* smi_data_buf_free: free SMI data buffer
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*/
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static void smi_data_buf_free(void)
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{
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if (!smi_data_buf)
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if (!smi_data_buf || wsmt_enabled)
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return;
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dev_dbg(&dcdbas_pdev->dev, "%s: phys: %x size: %lu\n",
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@ -86,7 +91,7 @@ static int smi_data_buf_realloc(unsigned long size)
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if (smi_data_buf_size >= size)
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return 0;
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if (size > MAX_SMI_DATA_BUF_SIZE)
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if (size > max_smi_data_buf_size)
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return -EINVAL;
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/* new buffer is needed */
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@ -169,7 +174,7 @@ static ssize_t smi_data_write(struct file *filp, struct kobject *kobj,
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{
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ssize_t ret;
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if ((pos + count) > MAX_SMI_DATA_BUF_SIZE)
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if ((pos + count) > max_smi_data_buf_size)
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return -EINVAL;
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mutex_lock(&smi_data_lock);
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@ -322,8 +327,20 @@ static ssize_t smi_request_store(struct device *dev,
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ret = count;
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break;
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case 1:
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/* Calling Interface SMI */
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smi_cmd->ebx = (u32) virt_to_phys(smi_cmd->command_buffer);
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/*
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* Calling Interface SMI
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*
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* Provide physical address of command buffer field within
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* the struct smi_cmd to BIOS.
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*
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* Because the address that smi_cmd (smi_data_buf) points to
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* will be from memremap() of a non-memory address if WSMT
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* is present, we can't use virt_to_phys() on smi_cmd, so
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* we have to use the physical address that was saved when
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* the virtual address for smi_cmd was received.
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*/
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smi_cmd->ebx = smi_data_buf_phys_addr +
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offsetof(struct smi_cmd, command_buffer);
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ret = dcdbas_smi_request(smi_cmd);
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if (!ret)
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ret = count;
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@ -482,6 +499,93 @@ static void dcdbas_host_control(void)
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}
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}
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/* WSMT */
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static u8 checksum(u8 *buffer, u8 length)
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{
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u8 sum = 0;
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u8 *end = buffer + length;
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while (buffer < end)
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sum += *buffer++;
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return sum;
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}
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static inline struct smm_eps_table *check_eps_table(u8 *addr)
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{
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struct smm_eps_table *eps = (struct smm_eps_table *)addr;
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if (strncmp(eps->smm_comm_buff_anchor, SMM_EPS_SIG, 4) != 0)
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return NULL;
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if (checksum(addr, eps->length) != 0)
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return NULL;
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return eps;
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}
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static int dcdbas_check_wsmt(void)
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{
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struct acpi_table_wsmt *wsmt = NULL;
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struct smm_eps_table *eps = NULL;
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u64 remap_size;
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u8 *addr;
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acpi_get_table(ACPI_SIG_WSMT, 0, (struct acpi_table_header **)&wsmt);
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if (!wsmt)
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return 0;
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/* Check if WSMT ACPI table shows that protection is enabled */
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if (!(wsmt->protection_flags & ACPI_WSMT_FIXED_COMM_BUFFERS) ||
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!(wsmt->protection_flags & ACPI_WSMT_COMM_BUFFER_NESTED_PTR_PROTECTION))
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return 0;
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/* Scan for EPS (entry point structure) */
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for (addr = (u8 *)__va(0xf0000);
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addr < (u8 *)__va(0x100000 - sizeof(struct smm_eps_table));
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addr += 16) {
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eps = check_eps_table(addr);
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if (eps)
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break;
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}
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if (!eps) {
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dev_dbg(&dcdbas_pdev->dev, "found WSMT, but no EPS found\n");
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return -ENODEV;
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}
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/*
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* Get physical address of buffer and map to virtual address.
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* Table gives size in 4K pages, regardless of actual system page size.
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*/
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if (upper_32_bits(eps->smm_comm_buff_addr + 8)) {
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dev_warn(&dcdbas_pdev->dev, "found WSMT, but EPS buffer address is above 4GB\n");
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return -EINVAL;
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}
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/*
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* Limit remap size to MAX_SMI_DATA_BUF_SIZE + 8 (since the first 8
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* bytes are used for a semaphore, not the data buffer itself).
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*/
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remap_size = eps->num_of_4k_pages * PAGE_SIZE;
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if (remap_size > MAX_SMI_DATA_BUF_SIZE + 8)
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remap_size = MAX_SMI_DATA_BUF_SIZE + 8;
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eps_buffer = memremap(eps->smm_comm_buff_addr, remap_size, MEMREMAP_WB);
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if (!eps_buffer) {
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dev_warn(&dcdbas_pdev->dev, "found WSMT, but failed to map EPS buffer\n");
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return -ENOMEM;
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}
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/* First 8 bytes is for a semaphore, not part of the smi_data_buf */
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smi_data_buf_phys_addr = eps->smm_comm_buff_addr + 8;
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smi_data_buf = eps_buffer + 8;
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smi_data_buf_size = remap_size - 8;
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max_smi_data_buf_size = smi_data_buf_size;
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wsmt_enabled = true;
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dev_info(&dcdbas_pdev->dev,
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"WSMT found, using firmware-provided SMI buffer.\n");
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return 1;
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}
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/**
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* dcdbas_reboot_notify: handle reboot notification for host control
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*/
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@ -548,6 +652,11 @@ static int dcdbas_probe(struct platform_device *dev)
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dcdbas_pdev = dev;
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/* Check if ACPI WSMT table specifies protected SMI buffer address */
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error = dcdbas_check_wsmt();
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if (error < 0)
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return error;
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/*
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* BIOS SMI calls require buffer addresses be in 32-bit address space.
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* This is done by setting the DMA mask below.
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@ -635,6 +744,8 @@ static void __exit dcdbas_exit(void)
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*/
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if (dcdbas_pdev)
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smi_data_buf_free();
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if (eps_buffer)
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memunmap(eps_buffer);
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platform_device_unregister(dcdbas_pdev_reg);
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platform_driver_unregister(&dcdbas_driver);
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}
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@ -53,6 +53,7 @@
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#define EXPIRED_TIMER (0)
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#define SMI_CMD_MAGIC (0x534D4931)
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#define SMM_EPS_SIG "$SCB"
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#define DCDBAS_DEV_ATTR_RW(_name) \
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DEVICE_ATTR(_name,0600,_name##_show,_name##_store);
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@ -103,5 +104,14 @@ struct apm_cmd {
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int dcdbas_smi_request(struct smi_cmd *smi_cmd);
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struct smm_eps_table {
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char smm_comm_buff_anchor[4];
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u8 length;
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u8 checksum;
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u8 version;
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u64 smm_comm_buff_addr;
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u64 num_of_4k_pages;
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} __packed;
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#endif /* _DCDBAS_H_ */
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