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

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

drivers/firmware/dcdbas.c

+117 −6
Original line number Diff line number Diff line
@@ -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);

}

drivers/firmware/dcdbas.h

+10 −0
Original line number Diff line number Diff line
@@ -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_ */

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