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SubjectRe: [PATCH 3/8] SFI: core support
On Tue, 23 Jun 2009 20:32:56 +0800
Andi Kleen <andi@firstfloor.org> wrote:

> > +static void __iomem *sfi_map_memory(u32 phys, u32 size)
> > +{
> > + if (!phys || !size)
> > + return NULL;
> > +
> > + if (sfi_tbl_permanant_mapped)
>
>
>
> > + return ioremap((unsigned long)phys, size);
> > + else
> > + return arch_early_ioremap((unsigned long)phys,
> > size); +}
>
> imho it would be cleaner if the callers just called these functions
> directly. Are the !phys !size checks really needed?

Andi,

Thanks for many good comments, will address them.

For this question, this sfi_map_memory() may get called before and after
the ioremap() is ready, so we add a permanent flag to judge the
environment and chose the right API automatically. e.g. after system is
booted, cpu freq driver will implicitly call this API to get freq info
>
>
> > +
> > +void sfi_tb_install_table(u64 addr, u32 flags)
> > +{
> > + struct sfi_table_header *table;
> > + u32 length;
> > +
> > + /* only map table header before knowing actual length */
> > + table = sfi_map_memory(addr, sizeof(struct
> > sfi_table_header));
> > + if (!table)
> > + return;
> > +
> > + length = table->length;
> > + sfi_unmap_memory(table, sizeof(struct sfi_table_header));
> > +
> > + table = sfi_map_memory(addr, length);
> > + if (!table)
> > + return;
>
>
> Since the mappings are always 4K you would only need to remap
> if the size is > PAGE_SIZE

yes, some of the table may be in one page, but some may not start at page
boundary and cross pages, we do it this way as this map/unmap/remap/unmap
routine only happen few times in boot phase.

>
> > +
> > + if (sfi_tb_verify_checksum(table, length))
> > + goto unmap_and_exit;
> > +
> > + /* Initialize sfi_tblist entry */
> > + sfi_tblist.tables[sfi_tblist.count].flags = flags;
> > + sfi_tblist.tables[sfi_tblist.count].address = addr;
> > + sfi_tblist.tables[sfi_tblist.count].pointer = NULL;
> > + memcpy(&sfi_tblist.tables[sfi_tblist.count].header,
> > + table, sizeof(struct sfi_table_header));
>
> To be honest I'm not sure why this list exists at all.
> Is it that difficult to just rewalk the firmware supplied
> table as needed?

Currently, there are about 10 SFI tables (more are expected), and most of
them will be parsed in driver initialization phase, like timer/cpu idle/
cpu frequency/rtc/system wake driver. Using a global list may save some
system overhead

Thanks,
Feng
>
>
> -andi


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