Re: [PATCH] MIPS: Scan the DMI system information

[Tiezhu Yang]

On 11/07/2019 08:35 AM, Jiaxun Yang wrote:
> ä 2019å11æ7æ GMT+08:00 äå12:05:41, Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> åå:
> > 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@xxxxxxxxxxx>
> > Signed-off-by: Yinglu Yang <yangyinglu@xxxxxxxxxxx>
> > Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> > ---
> > 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
> > +}
> Hi Tiezhu,
>
> It is really tricky to hijack dmi address here during remap.
> I think we should set the dmi table address at  dmi_scan.c by a marco or something else rather than hijack it during remap.

Hi Jiaxun,

Thanks for your review. I agree with you, let me think about it and try to
find a proper way, and then I will send a v2 patch.

> Btw: Probably we should set DMI default y when MACH_LOONGSON64 is set?

CONFIG_DMI is set to y by default, I think there is no need to select 
DMI when
set CONFIG_MACH_LOONGSON64.

Thanks,

Tiezhu Yang

> Thanks.