[PATCH 1/3] ARM: CSR: Adding CSR SiRFprimaII board support

[Barry Song]

2011/7/6 Russell King - ARM Linux <linux at arm.linux.org.uk>:
> On Wed, Jul 06, 2011 at 02:47:56AM -0700, Barry Song wrote:
>> diff --git a/arch/arm/mach-prima2/include/mach/io.h b/arch/arm/mach-prima2/include/mach/io.h
>> new file mode 100644
>> index 0000000..fc54f16
>> --- /dev/null
>> +++ b/arch/arm/mach-prima2/include/mach/io.h
>> @@ -0,0 +1,21 @@
>> +/*
>> + * arch/arm/mach-prima2/include/mach/io.h
>> + *
>> + * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
>> + *
>> + * Licensed under GPLv2 or later.
>> + */
>> +
>> +#ifndef __MACH_PRIMA2_IO_H
>> +#define __MACH_PRIMA2_IO_H
>> +
>> +#define IO_SPACE_LIMIT 0xffffffff
>
> Can folk please start putting comments in their io.h file explaining their
> choice for this definition?  Looking through the existing files, it is
> almost impossible to infer the reason the value was picked, which makes
> future maintanence a headache.
>
> IO_SPACE_LIMIT sets the upper bound for the PCI/ISA style IO accessor
> macros (inb, et.al.)
>
> My guidance is:
>
> 1. If you have no support for ISA/PCI/PC card drivers, then set this to
>   zero to prevent ISA/PCI drivers reserving IO port space.  You should
>   be able to leave __io() set to __typesafe_io() without risking any
>   ISA driver stamping on memory as those drivers should no longer
>   successfully initialize with this set to zero.
>
> 2. If you have MMIO-mapped IO space (eg, a PCI bridge which forwards
>   MMIO accesses in a window to PCI IO space) or equivalent, then set
>   this to the size of the window, or 64K-1.  Explain this.
>
> 3. If you have MMIO-mapped IO space which is scattered (eg, multiple
>   PC cards with their IO space individually mapped as separate 64K
>   blocks) then explain this and set it to 0xffffffff for the time
>   being.
>
> In any case, having the chosen value documented, and if it is for
> specific devices on the board, documenting that too, would really
> help.
>
> I shall be making this change to asm/io.h shortly:
>
>  #include <mach/io.h>
>
> +/*
> + * This is the limit of PCI/ISA/PC card IO space, which is by default
> + * 64K if we have PC card, PCI or ISA support.  Otherwise, default to
> + * zero to prevent ISA/PCI drivers claiming IO space (and potentially
> + * oopsing.)
> + *
> + * Only set this larger if you really need inb() et.al. to operate over
> + * a larger address space (eg, for multiple MMIO-mapped PC card sockets
> + * as found on SA11x0 and PXA.)
> + */
> +#ifndef IO_SPACE_LIMIT
> +#if defined(CONFIG_PCI) || defined(CONFIG_ISA) || defined(CONFIG_PCCARD)
> +#define IO_SPACE_LIMIT ((resource_size_t)0xffff)
> +#else
> +#define IO_SPACE_LIMIT ((resource_size_t)0)
> +#endif
> +#endif

if you define that in asm/io.h as you said:

#ifndef IO_SPACE_LIMIT
#if defined(PCMCIA_SOC_COMMON)
#define  IO_SPACE_LIMIT ((resource_size_t)0xffffffff)
#else
#if defined(CONFIG_PCI) || defined(CONFIG_ISA) || defined(CONFIG_PCCARD)
#define IO_SPACE_LIMIT ((resource_size_t)0xffff)
#else
#define IO_SPACE_LIMIT ((resource_size_t)0)
#endif
#endif
#endif

i'd like to delete IO_SPACE_LIMIT in my io.h.

otherwise, i'd like to try "#define IO_SPACE_LIMIT
((resource_size_t)0)" in my io.h since i have no real
CONFIG_PCI/ISA/PCCARD/PCMCIA_SOC_COMMON.

>
> Thanks.
>
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