[Patch v2 1/2] firmware: dmi_scan: add symbol to get SMBIOS entry area

[Ivan Khoronzhuk]

There are situations when code needs to access SMBIOS entry table
area. For example, to pass it via sysfs to userspace when it's not
allowed to get SMBIOS info via /dev/mem.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronz...@linaro.org>
---
 drivers/firmware/dmi_scan.c | 26 ++++++++++++++++++++++++++
 include/linux/dmi.h         |  3 +++
 2 files changed, 29 insertions(+)

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 420c8d8..d94c6b7 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -113,6 +113,8 @@ static void dmi_table(u8 *buf, int len, int num,
        }
 }
 
+static unsigned char smbios_header[32];
+static int smbios_header_size;
 static phys_addr_t dmi_base;
 static u16 dmi_len;
 static u16 dmi_num;
@@ -474,6 +476,8 @@ static int __init dmi_present(const u8 *buf)
        if (memcmp(buf, "_SM_", 4) == 0 &&
            buf[5] < 32 && dmi_checksum(buf, buf[5])) {
                smbios_ver = get_unaligned_be16(buf + 6);
+               smbios_header_size = buf[5];
+               memcpy(smbios_header, buf, smbios_header_size);
 
                /* Some BIOS report weird SMBIOS version, fix that up */
                switch (smbios_ver) {
@@ -505,6 +509,8 @@ static int __init dmi_present(const u8 *buf)
                                pr_info("SMBIOS %d.%d present.\n",
                                       dmi_ver >> 8, dmi_ver & 0xFF);
                        } else {
+                               smbios_header_size = 15;
+                               memcpy(smbios_header, buf, smbios_header_size);
                                dmi_ver = (buf[14] & 0xF0) << 4 |
                                           (buf[14] & 0x0F);
                                pr_info("Legacy DMI %d.%d present.\n",
@@ -531,6 +537,8 @@ static int __init dmi_smbios3_present(const u8 *buf)
                dmi_ver &= 0xFFFFFF;
                dmi_len = get_unaligned_le32(buf + 12);
                dmi_base = get_unaligned_le64(buf + 16);
+               smbios_header_size = buf[6];
+               memcpy(smbios_header, buf, smbios_header_size);
 
                /*
                 * The 64-bit SMBIOS 3.0 entry point no longer has a field
@@ -944,3 +952,21 @@ void dmi_memdev_name(u16 handle, const char **bank, const 
char **device)
        }
 }
 EXPORT_SYMBOL_GPL(dmi_memdev_name);
+
+/**
+ * dmi_get_smbios_entry_area - copy SMBIOS entry point area to array.
+ * @size - pointer to assign actual size of SMBIOS entry point area.
+ *
+ * returns NULL if table is not available, otherwise returns pointer on
+ * SMBIOS entry point area array.
+ */
+const u8 *dmi_get_smbios_entry_area(int *size)
+{
+       if (!smbios_header_size || !dmi_available)
+               return NULL;
+
+       *size = smbios_header_size;
+
+       return smbios_header;
+}
+EXPORT_SYMBOL_GPL(dmi_get_smbios_entry_area);
diff --git a/include/linux/dmi.h b/include/linux/dmi.h
index f820f0a..8e1a28d 100644
--- a/include/linux/dmi.h
+++ b/include/linux/dmi.h
@@ -109,6 +109,7 @@ extern int dmi_walk(void (*decode)(const struct dmi_header 
*, void *),
        void *private_data);
 extern bool dmi_match(enum dmi_field f, const char *str);
 extern void dmi_memdev_name(u16 handle, const char **bank, const char 
**device);
+const u8 *dmi_get_smbios_entry_area(int *size);
 
 #else
 
@@ -140,6 +141,8 @@ static inline void dmi_memdev_name(u16 handle, const char 
**bank,
                const char **device) { }
 static inline const struct dmi_system_id *
        dmi_first_match(const struct dmi_system_id *list) { return NULL; }
+static inline const u8 *dmi_get_smbios_entry_area(int *size)
+       { return NULL; }
 
 #endif
 
-- 
1.9.1

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