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Subject: Re: [PATCH REPLY] MIPS: Scan the DMI system information
To:     Jiaxun Yang <jiaxun.yang@flygoat.com>
References: <20191107112801.7037-1-jiaxun.yang@flygoat.com>
Cc:     linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        yangyinglu@loongson.cn, jdelvare@suse.de,
        Xuefeng Li <lixuefeng@loongson.cn>
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
Message-ID: <acd64ec9-e471-6fee-6505-ae3286a2972e@loongson.cn>
Date:   Fri, 8 Nov 2019 08:16:41 +0800
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On 11/07/2019 07:28 PM, Jiaxun Yang wrote:
> Hi Tiezhu and Jean,
>
> What about do like this?
> We shouldn't follow x86's Kconfig as most of MIPS devices
> don't support DMI.
>
> And, we can reuse map/unmap from io.h to reduce
> maintinance overhead.

Hi Jiaxun,

Thanks for your modification, it looks better, let me verify and test it,
and then I will send a v2 patch.

Thanks,

Tiezhu Yang

>
> Thanks
>
> Jiaxun
>
>> 8------------------------------------------------------8<
> 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@loongson.cn>
> Signed-off-by: Yinglu Yang <yangyinglu@loongson.cn>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> [jiaxun.yang@flygoat.com: Refine definitions and Kconfig]
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
>   arch/mips/Kconfig           |  9 +++++++++
>   arch/mips/include/asm/dmi.h | 20 ++++++++++++++++++++
>   arch/mips/kernel/setup.c    |  2 ++
>   drivers/firmware/dmi_scan.c |  6 +++++-
>   4 files changed, 36 insertions(+), 1 deletion(-)
>   create mode 100644 arch/mips/include/asm/dmi.h
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index c3a022ca3345..414f3a0ea397 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -2759,6 +2759,15 @@ 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.
> +
>   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 000000000000..5153ef6fe8a2
> --- /dev/null
> +++ b/arch/mips/include/asm/dmi.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_MIPS_DMI_H
> +#define _ASM_MIPS_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_MIPS_DMI_H */
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index c3d4212b5f1d..da7d312e20eb 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 35ed56b9c34f..ee2dbebf2063 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;
>