From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gabor Juhos <juhosg@openwrt.org>
Date: Sun, 03 Feb 2013 09:02:25 +0100
Subject: [U-Boot] [PATCH v2 02/10] MIPS: qemu-malta: add reset support
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2013.02.02. 20:35 keltez?ssel, Daniel Schwierzeck ?rta:

>> diff --git a/board/qemu-malta/qemu-malta.c b/board/qemu-malta/qemu-malta.c
>> index 9ba711d..9333242 100644
>> --- a/board/qemu-malta/qemu-malta.c
>> +++ b/board/qemu-malta/qemu-malta.c
>> @@ -8,6 +8,9 @@
>>
>>  #include <common.h>
>>
>> +#include <asm/io.h>
>> +#include <asm/malta.h>
>> +
>>  phys_size_t initdram(int board_type)
>>  {
>>         return CONFIG_SYS_MEM_SIZE;
>> @@ -18,3 +21,11 @@ int checkboard(void)
>>         puts("Board: MIPS Malta CoreLV (Qemu)\n");
>>         return 0;
>>  }
>> +
>> +void _machine_restart(void)
>> +{
>> +       void __iomem *reset_base;
>> +
>> +       reset_base = (void __iomem *) CKSEG1ADDR(MALTA_RESET_BASE);
>> +       __raw_writel(le32_to_cpu(GORESET), reset_base);
> 
> don't you need to swap from CPU endianess to register/bus endinaness?
> I think regisers/bus are always BE and only CPU changes between LE/BE.
> So we either need __raw_writel(cpu_to_be32(v),a) or writel_be32(v,a).

The register uses the same endianness as the CPU, so we have to write either a
LE or BE value depending on the CPU endianness.

This means that we should use the __raw_writel accessor with a plain GORESET
value. That method works in Linux but does not work in U-Boot.

The Malta board needs the CONFIG_SWAP_IO_SPACE for PCI device acccess. If this
config options is set then the __raw_writel accessor will swap the given value
on BE systems. So I have to pre-swap the value with le32_to_cpu to make it
working correctly.

The relevant definitions from 'arch/mips/include/asm/io.h':

> #if defined(CONFIG_SWAP_IO_SPACE) && defined(__MIPSEB__)
> 
> #define __ioswab8(x) (x)
> #define __ioswab16(x) swab16(x)
> #define __ioswab32(x) swab32(x)
> 
> #else
> ...
> #define writeb(b,addr) (*(volatile unsigned char *)(addr)) = (b)
> #define writew(b,addr) (*(volatile unsigned short *)(addr)) = (__ioswab16(b))
> #define writel(b,addr) (*(volatile unsigned int *)(addr)) = (__ioswab32(b))
> #define __raw_writeb writeb
> #define __raw_writew writew
> #define __raw_writel writel

Maybe here is the time to fix these accessors in asm/io.h?

-Gabor