Commit 12c956c4 authored by Stuart Hayes's avatar Stuart Hayes Committed by Andy Shevchenko

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: default avatarStuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
parent 6aecee6a
......@@ -21,6 +21,7 @@
*/
#include <linux/platform_device.h>
#include <linux/acpi.h>
#include <linux/dma-mapping.h>
#include <linux/errno.h>
#include <linux/cpu.h>
......@@ -41,7 +42,7 @@
#include "dcdbas.h"
#define DRIVER_NAME "dcdbas"
#define DRIVER_VERSION "5.6.0-3.2"
#define DRIVER_VERSION "5.6.0-3.3"
#define DRIVER_DESCRIPTION "Dell Systems Management Base Driver"
static struct platform_device *dcdbas_pdev;
......@@ -49,19 +50,23 @@ static struct platform_device *dcdbas_pdev;
static u8 *smi_data_buf;
static dma_addr_t smi_data_buf_handle;
static unsigned long smi_data_buf_size;
static unsigned long max_smi_data_buf_size = MAX_SMI_DATA_BUF_SIZE;
static u32 smi_data_buf_phys_addr;
static DEFINE_MUTEX(smi_data_lock);
static u8 *eps_buffer;
static unsigned int host_control_action;
static unsigned int host_control_smi_type;
static unsigned int host_control_on_shutdown;
static bool wsmt_enabled;
/**
* smi_data_buf_free: free SMI data buffer
*/
static void smi_data_buf_free(void)
{
if (!smi_data_buf)
if (!smi_data_buf || wsmt_enabled)
return;
dev_dbg(&dcdbas_pdev->dev, "%s: phys: %x size: %lu\n",
......@@ -86,7 +91,7 @@ static int smi_data_buf_realloc(unsigned long size)
if (smi_data_buf_size >= size)
return 0;
if (size > MAX_SMI_DATA_BUF_SIZE)
if (size > max_smi_data_buf_size)
return -EINVAL;
/* new buffer is needed */
......@@ -169,7 +174,7 @@ static ssize_t smi_data_write(struct file *filp, struct kobject *kobj,
{
ssize_t ret;
if ((pos + count) > MAX_SMI_DATA_BUF_SIZE)
if ((pos + count) > max_smi_data_buf_size)
return -EINVAL;
mutex_lock(&smi_data_lock);
......@@ -322,8 +327,20 @@ static ssize_t smi_request_store(struct device *dev,
ret = count;
break;
case 1:
/* Calling Interface SMI */
smi_cmd->ebx = (u32) virt_to_phys(smi_cmd->command_buffer);
/*
* Calling Interface SMI
*
* Provide physical address of command buffer field within
* the struct smi_cmd to BIOS.
*
* Because the address that smi_cmd (smi_data_buf) points to
* will be from memremap() of a non-memory address if WSMT
* is present, we can't use virt_to_phys() on smi_cmd, so
* we have to use the physical address that was saved when
* the virtual address for smi_cmd was received.
*/
smi_cmd->ebx = smi_data_buf_phys_addr +
offsetof(struct smi_cmd, command_buffer);
ret = dcdbas_smi_request(smi_cmd);
if (!ret)
ret = count;
......@@ -482,6 +499,93 @@ static void dcdbas_host_control(void)
}
}
/* WSMT */
static u8 checksum(u8 *buffer, u8 length)
{
u8 sum = 0;
u8 *end = buffer + length;
while (buffer < end)
sum += *buffer++;
return sum;
}
static inline struct smm_eps_table *check_eps_table(u8 *addr)
{
struct smm_eps_table *eps = (struct smm_eps_table *)addr;
if (strncmp(eps->smm_comm_buff_anchor, SMM_EPS_SIG, 4) != 0)
return NULL;
if (checksum(addr, eps->length) != 0)
return NULL;
return eps;
}
static int dcdbas_check_wsmt(void)
{
struct acpi_table_wsmt *wsmt = NULL;
struct smm_eps_table *eps = NULL;
u64 remap_size;
u8 *addr;
acpi_get_table(ACPI_SIG_WSMT, 0, (struct acpi_table_header **)&wsmt);
if (!wsmt)
return 0;
/* Check if WSMT ACPI table shows that protection is enabled */
if (!(wsmt->protection_flags & ACPI_WSMT_FIXED_COMM_BUFFERS) ||
!(wsmt->protection_flags & ACPI_WSMT_COMM_BUFFER_NESTED_PTR_PROTECTION))
return 0;
/* Scan for EPS (entry point structure) */
for (addr = (u8 *)__va(0xf0000);
addr < (u8 *)__va(0x100000 - sizeof(struct smm_eps_table));
addr += 16) {
eps = check_eps_table(addr);
if (eps)
break;
}
if (!eps) {
dev_dbg(&dcdbas_pdev->dev, "found WSMT, but no EPS found\n");
return -ENODEV;
}
/*
* Get physical address of buffer and map to virtual address.
* Table gives size in 4K pages, regardless of actual system page size.
*/
if (upper_32_bits(eps->smm_comm_buff_addr + 8)) {
dev_warn(&dcdbas_pdev->dev, "found WSMT, but EPS buffer address is above 4GB\n");
return -EINVAL;
}
/*
* Limit remap size to MAX_SMI_DATA_BUF_SIZE + 8 (since the first 8
* bytes are used for a semaphore, not the data buffer itself).
*/
remap_size = eps->num_of_4k_pages * PAGE_SIZE;
if (remap_size > MAX_SMI_DATA_BUF_SIZE + 8)
remap_size = MAX_SMI_DATA_BUF_SIZE + 8;
eps_buffer = memremap(eps->smm_comm_buff_addr, remap_size, MEMREMAP_WB);
if (!eps_buffer) {
dev_warn(&dcdbas_pdev->dev, "found WSMT, but failed to map EPS buffer\n");
return -ENOMEM;
}
/* First 8 bytes is for a semaphore, not part of the smi_data_buf */
smi_data_buf_phys_addr = eps->smm_comm_buff_addr + 8;
smi_data_buf = eps_buffer + 8;
smi_data_buf_size = remap_size - 8;
max_smi_data_buf_size = smi_data_buf_size;
wsmt_enabled = true;
dev_info(&dcdbas_pdev->dev,
"WSMT found, using firmware-provided SMI buffer.\n");
return 1;
}
/**
* dcdbas_reboot_notify: handle reboot notification for host control
*/
......@@ -548,6 +652,11 @@ static int dcdbas_probe(struct platform_device *dev)
dcdbas_pdev = dev;
/* Check if ACPI WSMT table specifies protected SMI buffer address */
error = dcdbas_check_wsmt();
if (error < 0)
return error;
/*
* BIOS SMI calls require buffer addresses be in 32-bit address space.
* This is done by setting the DMA mask below.
......@@ -635,6 +744,8 @@ static void __exit dcdbas_exit(void)
*/
if (dcdbas_pdev)
smi_data_buf_free();
if (eps_buffer)
memunmap(eps_buffer);
platform_device_unregister(dcdbas_pdev_reg);
platform_driver_unregister(&dcdbas_driver);
}
......
......@@ -53,6 +53,7 @@
#define EXPIRED_TIMER (0)
#define SMI_CMD_MAGIC (0x534D4931)
#define SMM_EPS_SIG "$SCB"
#define DCDBAS_DEV_ATTR_RW(_name) \
DEVICE_ATTR(_name,0600,_name##_show,_name##_store);
......@@ -103,5 +104,14 @@ struct apm_cmd {
int dcdbas_smi_request(struct smi_cmd *smi_cmd);
struct smm_eps_table {
char smm_comm_buff_anchor[4];
u8 length;
u8 checksum;
u8 version;
u64 smm_comm_buff_addr;
u64 num_of_4k_pages;
} __packed;
#endif /* _DCDBAS_H_ */
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment