Re: [PATCH for-6.0 2/2] aspeed/smc: Add extra controls to request DMA

[Cédric Le Goater]

On 11/25/20 3:49 AM, Joel Stanley wrote:
> On Fri, 20 Nov 2020 at 16:16, Cédric Le Goater <clg@kaod.org> wrote:
>>
>> The controller has a set of hidden bits to request/grant DMA access.
> 
> Do you have the ast2600 datasheet? It describes these bits:
> 
> 31 RW DMA Request
> 
> Write SPIR80 = 0xAEED0000 to set this bit ot '1'.
> And hardware will clear the request to '0' after DMA done, or FW can
> clear to '0' by writing SPIR80 = 0xDEEA0000.
> 
> 30 RO DMA Grant
> 
> 0: DMA is not allowed to be used. All DMA related control registers
> are not allowed to be written.
> 1: DMA is granted to be used.

I see them now :) They are under the SPI controllers but not under 
the BMC SPI controller where I was looking. May be the datasheet 
was updated now ? 
 
> Do you want to add the magic behavior to your model?

Yes. The Aspeed SPI driver needs them. I think the model can be better.
I will send a v2.

Thanks,

C.

> 
>>
>> Cc: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
>> ---
>>  hw/ssi/aspeed_smc.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/hw/ssi/aspeed_smc.c b/hw/ssi/aspeed_smc.c
>> index e3d5e26058c0..c1557ef5d848 100644
>> --- a/hw/ssi/aspeed_smc.c
>> +++ b/hw/ssi/aspeed_smc.c
>> @@ -127,6 +127,8 @@
>>
>>  /* DMA Control/Status Register */
>>  #define R_DMA_CTRL        (0x80 / 4)
>> +#define   DMA_CTRL_REQUEST      (1 << 31)
>> +#define   DMA_CTRL_GRANT        (1 << 30)
>>  #define   DMA_CTRL_DELAY_MASK   0xf
>>  #define   DMA_CTRL_DELAY_SHIFT  8
>>  #define   DMA_CTRL_FREQ_MASK    0xf
>> @@ -1237,6 +1239,11 @@ static void aspeed_smc_dma_done(AspeedSMCState *s)
>>
>>  static void aspeed_smc_dma_ctrl(AspeedSMCState *s, uint64_t dma_ctrl)
>>  {
>> +    if (dma_ctrl & DMA_CTRL_REQUEST) {
>> +            s->regs[R_DMA_CTRL] = dma_ctrl | DMA_CTRL_GRANT;
>> +            return;
>> +    }
>> +
>>      if (!(dma_ctrl & DMA_CTRL_ENABLE)) {
>>          s->regs[R_DMA_CTRL] = dma_ctrl;
>>
>> --
>> 2.26.2
>>