[PATCH] PowerPC: Remove hardcoded BAT configuration of IMMR in CPM early debug console

[Martyn Welch]

Martyn Welch wrote:
> Scott Wood wrote:
>   
>> On 05/28/2010 10:18 AM, Martyn Welch wrote:
>>     
>>> The CPM early debug console hardcodes the BAT to cover the IMMR at
>>> 0xf0000000. The IMMR (on the mpc8270 at the very least) can be set to a
>>> number of locations with bootstrap configuration, which are outside the
>>> hardcoded BAT configuration.
>>>
>>> This patch determines the correct location at which to configure a BAT
>>> during the boot process from the supplied PPC_EARLY_DEBUG_CPM_ADDR.
>>>
>>> Signed-off-by: Martyn Welch<martyn.welch at ge.com>
>>> ---
>>>
>>>   arch/powerpc/kernel/head_32.S    |    5 +++--
>>>   arch/powerpc/sysdev/cpm_common.c |    4 +++-
>>>   2 files changed, 6 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/arch/powerpc/kernel/head_32.S
>>> b/arch/powerpc/kernel/head_32.S
>>> index e025e89..861cace 100644
>>> --- a/arch/powerpc/kernel/head_32.S
>>> +++ b/arch/powerpc/kernel/head_32.S
>>> @@ -1194,12 +1194,13 @@ setup_disp_bat:
>>>   #endif /* CONFIG_BOOTX_TEXT */
>>>
>>>   #ifdef CONFIG_PPC_EARLY_DEBUG_CPM
>>> +#define PPC_EARLY_DEBUG_CPM_ADDR
>>> ASM_CONST(CONFIG_PPC_EARLY_DEBUG_CPM_ADDR)
>>>   setup_cpm_bat:
>>> -    lis    r8, 0xf000
>>> +    lis    r8, PPC_EARLY_DEBUG_CPM_ADDR at ha
>>>       ori    r8, r8,    0x002a
>>>       mtspr    SPRN_DBAT1L, r8
>>>
>>> -    lis    r11, 0xf000
>>> +    lis    r11, PPC_EARLY_DEBUG_CPM_ADDR at ha
>>>       ori    r11, r11, (BL_1M << 2) | 2
>>>       mtspr    SPRN_DBAT1U, r11
>>>       
>> Only the physical address should depend on where IMMR is.  We should
>> use fixmap instead of an arbitrary address for the effective address.
>> There's a existing FIX_EARLY_DEBUG_BASE, but it's only 128 KiB so
>> we'll have to either grow it, or map only a subset of IMMR.
>>
>>     
>
> I think that's a more fundamental change to CPM early debug than I can
> handle right now.
>
>   
>> Plus, CONFIG_PPC_EARLY_DEBUG_CPM_ADDR points to the TX descriptor, not
>> to the beginning of IMMR, so you should mask off the lower 20 bits
>> (the offset is probably less than 64K, and the BAT might just ignore
>> the extra bits anyway, but why take chances?).
>>
>>     
>
> I assume that an extra instruction "andi   r8, r8, 0xfff0" after each
> "lis" instruction  would be what you are looking for?
>
>   
"andis" even.

Martyn

> Martyn
>
>   
>> -Scott
>>     
>
>
>   


-- 
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