Re: [PATCH v13 1/9] esp: add pseudo-DMA as used by Macintosh

[Laurent Vivier]

Le 02/10/2019 à 13:10, Philippe Mathieu-Daudé a écrit :
> On 9/27/19 11:04 AM, Laurent Vivier wrote:
>> There is no DMA in Quadra 800, so the CPU reads/writes the data from the
>> PDMA register (offset 0x100, ESP_PDMA in hw/m68k/q800.c) and copies them
>> to/from the memory.
>>
>> There is a nice assembly loop in the kernel to do that, see
>> linux/drivers/scsi/mac_esp.c:MAC_ESP_PDMA_LOOP().
>>
>> The start of the transfer is triggered by the DREQ interrupt (see linux
>> mac_esp_send_pdma_cmd()), the CPU polls on the IRQ flag to start the
>> transfer after a SCSI command has been sent (in Quadra 800 it goes
>> through the VIA2, the via2-irq line and the vIFR register)
>>
>> The Macintosh hardware includes hardware handshaking to prevent the CPU
>> from reading invalid data or writing data faster than the peripheral
>> device can accept it.
>>
>> This is the "blind mode", and from the doc:
>> "Approximate maximum SCSI transfer rates within a blocks are 1.4 MB per
>> second for blind transfers in the Macintosh II"
>>
>> Some references can be found in:
>>    Apple Macintosh Family Hardware Reference, ISBN 0-201-19255-1
>>    Guide to the Macintosh Family Hardware, ISBN-0-201-52405-8
>>
>> Acked-by: Dr. David Alan Gilbert <address@hidden>
>> Co-developed-by: Mark Cave-Ayland <address@hidden>
>> Signed-off-by: Mark Cave-Ayland <address@hidden>
>> Signed-off-by: Laurent Vivier <address@hidden>
>> ---
>>   hw/scsi/esp.c         | 338 ++++++++++++++++++++++++++++++++++++++----
>>   include/hw/scsi/esp.h |  15 ++
> 
> I recommend you to install the scripts/git.orderfile file.

done

> 
>>   2 files changed, 324 insertions(+), 29 deletions(-)
>>
...
>> --- a/include/hw/scsi/esp.h
>> +++ b/include/hw/scsi/esp.h
>> @@ -14,10 +14,18 @@ typedef void (*ESPDMAMemoryReadWriteFunc)(void
>> *opaque, uint8_t *buf, int len);
>>     typedef struct ESPState ESPState;
>>   +enum pdma_origin_id {
>> +    PDMA,
>> +    TI,
>> +    CMD,
>> +    ASYNC,
>> +};
>> +
>>   struct ESPState {
>>       uint8_t rregs[ESP_REGS];
>>       uint8_t wregs[ESP_REGS];
>>       qemu_irq irq;
>> +    qemu_irq irq_data;
>>       uint8_t chip_id;
>>       bool tchi_written;
>>       int32_t ti_size;
>> @@ -48,6 +56,12 @@ struct ESPState {
>>       ESPDMAMemoryReadWriteFunc dma_memory_write;
>>       void *dma_opaque;
>>       void (*dma_cb)(ESPState *s);
>> +    uint8_t pdma_buf[32];
>> +    int pdma_origin;
> 
> 'int' -> 'enum pdma_origin_id'
> 
> You can also declare the enum in place:
> 
>        enum pdma_origin_id {
>            PDMA,
>            TI,
>            CMD,
>            ASYNC,
>        } pdma_origin;

If I remember correctly I put an "int" here because I didn't find the
VMSTATE_XXX() to use and VMSTATE_INT32() doesn't like the enum type
(which should be treated as an int).

Thanks,
Laurent