[coreboot] v2[PATCH]RCA RM4100 i82830 support

[joe at smittys.pointclark.net]

Quoting joe at smittys.pointclark.net:

> Quoting Corey Osgood <corey.osgood at gmail.com>:
>
>>
>> On Tue, 2008-02-26 at 16:19 -0500, joe at smittys.pointclark.net wrote:
>>> >> +static void do_ram_command(const struct mem_controller *ctrl,
>>> >> uint32_t command, uint32_t addr_offset)
>>> >> +{
>>> >> <snip>
>>> >> +
>>> >> +	/* Read from (DIMM start address + addr_offset). */
>>> >> +	read32(0 + addr_offset);	//first offset is always 0
>>> >> +}
>>> >
>>> > This isn't ready for multiple dimms yet. See the cn700 patch I
>>> > recently sent (but haven't committed yet, I think it was acked).
>>> >
>>> Oh you mean this? What do I need to do to adapt it for the i82830?
>>>
>>> +	/* NOTE: Dual-sided ready */
>>>   	read32(0 + addr_offset);
>>> +	for(i = 0; i < (ARRAY_SIZE(ctrl->channel0) * 2); i++) {
>>> +		reg8 = pci_read_config8(ctrl->d0f3, 0x40 + i);
>>> + 	if(reg8) read32((reg8 << 26) + addr_offset);
>>> + }
>>
>> This reads from register 0x40 + i, where 0x40 is the top of the first
>> dimm, and i counts to the max number of dimms.
>
> Why read this from a register?? Why not just use (i = 0; i <
> DIMM_SOCKETS; i++)
>
>> Reg 0x40 contains bits
>> 33:26 of the top address, hence the << 26. So you'd need to adjust both
>> of these to fit the i830's DRB mechanism. If the i830 uses an ugly
>> format like the i810 does, then it may be easier to store the size in
>> scratch registers somewhere after it's calculated, and then use those
>> values instead. Sorry I can't get more specific, I've got to head out to
>> my next service call.
>>
> The DRB i830 is not ugly it is very simple, simple, simple. So simple
> that it just calculates the memory size in ticks of 32 per side
(Sorry typo I meant) +
> the next side up to 4 sides. Like this:
>
> Example: 128MB SINGLE sided so-dimm in slot 1
>           128MB DOUBLE sided so-dimm in slot 2
>
> There are 4 DRB registers(actually 6 but but only 4 that are usable -
> Intel design glitch), 1 for each side. So in this example they would
> look like this:
>
> DRB1 = 0x04
> DRB2 = 0x04
> DRB3 = 0x06
> DRB4 = 0x08
>
> So if we needed to convert this we would do something like this (DRB *
> 32) * 1024 correct? But if we just need to calculate the end of
> so-dimm #1 and the start of so-dimm #2 the only important register
> would be DRB2 (side 2 of so-dimm #1) and DRB3(side 1 of so-dimm #2),
> correct?
>
> Thanks - Joe
>
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Thanks - Joe