[PATCH v2] MIPS: Scan the DMI system information

[Tiezhu Yang <yangtiezhu@loongson.cn>]

Enable DMI scanning on the MIPS architecture, this setups DMI identifiers
(dmi_system_id) for printing it out on task dumps and prepares DIMM entry
information (dmi_memdev_info) from the SMBIOS table. With this patch, the
driver can easily match various of mainboards.

In the SMBIOS reference specification, the table anchor string "_SM_" is
present in the address range 0xF0000 to 0xFFFFF on a 16-byte boundary,
but there exists a special case for Loongson platform, when call function
dmi_early_remap, it should specify the start address to 0xFFFE000 due to
it is reserved for SMBIOS and can be normally access in the BIOS.

This patch works fine on the Loongson 3A3000 platform which belongs to
MIPS architecture and has no influence on the other architectures such
as x86 and ARM.

Co-developed-by: Yinglu Yang <yangyinglu@loongson.cn>
Signed-off-by: Yinglu Yang <yangyinglu@loongson.cn>
[jiaxun.yang@flygoat.com: Refine definitions and Kconfig]
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---

v2:
  - add SMBIOS_ENTRY_POINT_SCAN_START suggested by Jean
  - refine definitions and Kconfig by Jiaxun

 arch/mips/Kconfig           | 10 ++++++++++
 arch/mips/include/asm/dmi.h | 20 ++++++++++++++++++++
 arch/mips/kernel/setup.c    |  2 ++
 drivers/firmware/dmi_scan.c |  6 +++++-
 4 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 arch/mips/include/asm/dmi.h

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 7cb8947..6393551 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2757,6 +2757,16 @@ config HW_PERF_EVENTS
 	  Enable hardware performance counter support for perf events. If
 	  disabled, perf events will use software events only.
 
+config DMI
+	default y if MACH_LOONGSON64
+	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
+	bool "Enable DMI scanning"
+	help
+	  Enabled scanning of DMI to identify machine quirks. Say Y
+	  here unless you have verified that your setup is not
+	  affected by entries in the DMI blacklist. Required by PNP
+	  BIOS code.
+
 config SMP
 	bool "Multi-Processing support"
 	depends on SYS_SUPPORTS_SMP
diff --git a/arch/mips/include/asm/dmi.h b/arch/mips/include/asm/dmi.h
new file mode 100644
index 0000000..27415a2
--- /dev/null
+++ b/arch/mips/include/asm/dmi.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_DMI_H
+#define _ASM_DMI_H
+
+#include <linux/io.h>
+#include <linux/memblock.h>
+
+#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)
+
+/* MIPS initialize DMI scan before SLAB is ready, so we use memblock here */
+#define dmi_alloc(l)			memblock_alloc_low(l, PAGE_SIZE)
+
+#if defined(CONFIG_MACH_LOONGSON64)
+#define SMBIOS_ENTRY_POINT_SCAN_START	0xFFFE000
+#endif
+
+#endif /* _ASM_DMI_H */
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index c3d4212..da7d312 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -28,6 +28,7 @@
 #include <linux/decompress/generic.h>
 #include <linux/of_fdt.h>
 #include <linux/of_reserved_mem.h>
+#include <linux/dmi.h>
 
 #include <asm/addrspace.h>
 #include <asm/bootinfo.h>
@@ -802,6 +803,7 @@ void __init setup_arch(char **cmdline_p)
 #endif
 
 	arch_mem_init(cmdline_p);
+	dmi_setup();
 
 	resource_init();
 	plat_smp_setup();
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 35ed56b..161bbf1 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -11,6 +11,10 @@
 #include <asm/dmi.h>
 #include <asm/unaligned.h>
 
+#ifndef SMBIOS_ENTRY_POINT_SCAN_START
+#define SMBIOS_ENTRY_POINT_SCAN_START 0xF0000
+#endif
+
 struct kobject *dmi_kobj;
 EXPORT_SYMBOL_GPL(dmi_kobj);
 
@@ -661,7 +665,7 @@ static void __init dmi_scan_machine(void)
 			return;
 		}
 	} else if (IS_ENABLED(CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK)) {
-		p = dmi_early_remap(0xF0000, 0x10000);
+		p = dmi_early_remap(SMBIOS_ENTRY_POINT_SCAN_START, 0x10000);
 		if (p == NULL)
 			goto error;
 
-- 
2.1.0