firmware/dmi_scan: generalize for use by other archs

This patch makes a couple of changes to the SMBIOS/DMI scanning
code so it can be used on other archs (such as ARM and arm64):
(a) wrap the calls to ioremap()/iounmap(), this allows the use of a
    flavor of ioremap() more suitable for random unaligned access;
(b) allow the non-EFI fallback probe into hardcoded physical address
    0xF0000 to be disabled.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 13 insertions, 10 deletions

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 074787281c94..5a29fac951ec 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -108,6 +108,9 @@ config DMI_SYSFS
           under /sys/firmware/dmi when this option is enabled and
           loaded.
 
+config DMI_SCAN_MACHINE_NON_EFI_FALLBACK
+        bool
+
 config ISCSI_IBFT_FIND
         bool "iSCSI Boot Firmware Table Attributes"
         depends on X86
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index c7e81ff8f3ef..17afc51f3054 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -116,7 +116,7 @@ static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,
 {
         u8 *buf;
 
-        buf = dmi_ioremap(dmi_base, dmi_len);
+        buf = dmi_early_remap(dmi_base, dmi_len);
         if (buf == NULL)
                 return -1;
 
@@ -124,7 +124,7 @@ static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,
 
         add_device_randomness(buf, dmi_len);
 
-        dmi_iounmap(buf, dmi_len);
+        dmi_early_unmap(buf, dmi_len);
         return 0;
 }
 
@@ -527,18 +527,18 @@ void __init dmi_scan_machine(void)
                  * needed during early boot.  This also means we can
                  * iounmap the space when we're done with it.
                  */
-                p = dmi_ioremap(efi.smbios, 32);
+                p = dmi_early_remap(efi.smbios, 32);
                 if (p == NULL)
                         goto error;
                 memcpy_fromio(buf, p, 32);
-                dmi_iounmap(p, 32);
+                dmi_early_unmap(p, 32);
 
                 if (!dmi_present(buf)) {
                         dmi_available = 1;
                         goto out;
                 }
-        } else {
-                p = dmi_ioremap(0xF0000, 0x10000);
+        } else if (IS_ENABLED(CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK)) {
+                p = dmi_early_remap(0xF0000, 0x10000);
                 if (p == NULL)
                         goto error;
 
@@ -554,12 +554,12 @@ void __init dmi_scan_machine(void)
                         memcpy_fromio(buf + 16, q, 16);
                         if (!dmi_present(buf)) {
                                 dmi_available = 1;
-                                dmi_iounmap(p, 0x10000);
+                                dmi_early_unmap(p, 0x10000);
                                 goto out;
                         }
                         memcpy(buf, buf + 16, 16);
                 }
-                dmi_iounmap(p, 0x10000);
+                dmi_early_unmap(p, 0x10000);
         }
  error:
         pr_info("DMI not present or invalid.\n");
@@ -831,13 +831,13 @@ int dmi_walk(void (*decode)(const struct dmi_header *, void *),
         if (!dmi_available)
                 return -1;
 
-        buf = ioremap(dmi_base, dmi_len);
+        buf = dmi_remap(dmi_base, dmi_len);
         if (buf == NULL)
                 return -1;
 
         dmi_table(buf, dmi_len, dmi_num, decode, private_data);
 
-        iounmap(buf);
+        dmi_unmap(buf);
         return 0;
 }
 EXPORT_SYMBOL_GPL(dmi_walk);