[PATCH] arm64: dmi: Add SMBIOS/DMI support

* [PATCH] arm64: dmi: Add SMBIOS/DMI support
@ 2014-07-31 12:47 Ard Biesheuvel
  2014-07-31 12:48 ` Ard Biesheuvel
  0 siblings, 1 reply; 10+ messages in thread
From: Ard Biesheuvel @ 2014-07-31 12:47 UTC (permalink / raw)
  To: linux-arm-kernel

From: Yi Li <yi.li@linaro.org>

SMbios is important for server hardware vendors. It implements a spec for
providing descriptive information about the platform. Things like serial
numbers, physical layout of the ports, build configuration data, and the like.

This has been tested by dmidecode and lshw tools.

Signed-off-by: Yi Li <yi.li@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---

It turns out that efi_lookup_mapped_addr() is not appropriate after all for
remapping the address of the SMBIOS tables. The reason is that the UEFI spec
forbids virtual mappings being requested for configuration tables (which is not
currently honored by Tianocore/EDK2)


 arch/arm64/Kconfig           | 11 +++++++++++
 arch/arm64/include/asm/dmi.h | 33 +++++++++++++++++++++++++++++++++
 arch/arm64/kernel/setup.c    |  2 ++
 3 files changed, 46 insertions(+)
 create mode 100644 arch/arm64/include/asm/dmi.h

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 839f48c26ef0..0b2350470ac9 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -308,6 +308,17 @@ config EFI
 	  allow the kernel to be booted as an EFI application. This
 	  is only useful on systems that have UEFI firmware.
 
+config DMI
+	bool "Enable support for SMBIOS (DMI) tables"
+	depends on EFI
+	default y
+	help
+	  This enables SMBIOS/DMI feature for systems.
+
+	  This option is only useful on systems that have UEFI firmware.
+	  However, even with this option, the resultant kernel should
+	  continue to boot on existing non-UEFI platforms.
+
 endmenu
 
 menu "Userspace binary formats"
diff --git a/arch/arm64/include/asm/dmi.h b/arch/arm64/include/asm/dmi.h
new file mode 100644
index 000000000000..0a07357bb776
--- /dev/null
+++ b/arch/arm64/include/asm/dmi.h
@@ -0,0 +1,33 @@
+/*
+ * arch/arm64/include/asm/dmi.h
+ *
+ * Copyright (C) 2013 Linaro Limited.
+ * Written by: Yi Li (yi.li at linaro.org)
+ *
+ * based on arch/ia64/include/asm/dmi.h
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef __ASM_DMI_H
+#define __ASM_DMI_H
+
+#include <linux/io.h>
+#include <linux/slab.h>
+
+/*
+ * According to section 2.3.6 of the UEFI spec, the firmware must not request
+ * a virtual mapping for configuration tables such as SMBIOS. This means we have
+ * to map them before use. As SMBIOS tables are typed as EfiRuntimeServicesData,
+ * they should always reside in DRAM, so we can use ioremap_cache() here, which
+ * will give us the existing linear mapping if the address is covered by it.
+ */
+#define dmi_early_remap(x, l)		ioremap_cache(x, l)
+#define dmi_early_unmap(x, l)		iounmap(x)
+#define dmi_remap(x, l)			ioremap_cache(x, l)
+#define dmi_unmap(x)			iounmap(x)
+#define dmi_alloc(l)			kzalloc(l, GFP_KERNEL)
+
+#endif
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 46d1125571f6..4075e46282b1 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -43,6 +43,7 @@
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
 #include <linux/efi.h>
+#include <linux/dmi.h>
 
 #include <asm/fixmap.h>
 #include <asm/cputype.h>
@@ -413,6 +414,7 @@ void __init setup_arch(char **cmdline_p)
 static int __init arm64_device_init(void)
 {
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
+	dmi_scan_machine();
 	return 0;
 }
 arch_initcall_sync(arm64_device_init);
-- 
1.8.3.2

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