linux-kernel - [PATCH] MIPS: Scan the DMI system information

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Date:   Thu,  7 Nov 2019 00:05:41 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        James Hogan <jhogan@...nel.org>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yinglu Yang <yangyinglu@...ngson.cn>
Subject: [PATCH] MIPS: Scan the DMI system information

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.

Co-developed-by: Yinglu Yang <yangyinglu@...ngson.cn>
Signed-off-by: Yinglu Yang <yangyinglu@...ngson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
 arch/mips/Kconfig           | 12 ++++++++++++
 arch/mips/include/asm/dmi.h | 43 +++++++++++++++++++++++++++++++++++++++++++
 arch/mips/kernel/setup.c    |  2 ++
 3 files changed, 57 insertions(+)
 create mode 100644 arch/mips/include/asm/dmi.h

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 7cb8947..0a67b18 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2757,6 +2757,18 @@ config HW_PERF_EVENTS
 	  Enable hardware performance counter support for perf events. If
 	  disabled, perf events will use software events only.
 
+# Mark as expert because too many people got it wrong.
+# The code disables itself when not needed.
+config DMI
+	default y
+	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
+	bool "Enable DMI scanning" if EXPERT
+	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..1f3da37
--- /dev/null
+++ b/arch/mips/include/asm/dmi.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_MIPS_DMI_H
+#define _ASM_MIPS_DMI_H
+
+#define dmi_early_remap		mips_early_memremap
+#define dmi_early_unmap		mips_early_memunmap
+#define dmi_remap(_x, _l)	mips_memremap(_x, _l, MEMREMAP_WB)
+#define dmi_unmap(_x)		mips_memunmap(_x)
+
+#define dmi_alloc(l)		memblock_alloc_low(l, PAGE_SIZE)
+
+void __init *mips_early_memremap(resource_size_t phys_addr, unsigned long size)
+{
+#if defined(CONFIG_MACH_LOONGSON64)
+	if (phys_addr == 0xF0000)
+		phys_addr = 0xFFFE000;
+
+	return (void *)TO_CAC(phys_addr);
+#else
+	return NULL;
+#endif
+}
+
+void __init mips_early_memunmap(void *addr, unsigned long size)
+{
+
+}
+
+void *mips_memremap(resource_size_t offset, size_t size, unsigned long flags)
+{
+#if defined(CONFIG_MACH_LOONGSON64)
+	return (void *)TO_CAC(offset);
+#else
+	return NULL;
+#endif
+}
+
+void mips_memunmap(void *addr)
+{
+
+}
+
+#endif /* _ASM_MIPS_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();
-- 
2.1.0