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

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 10/2/19 2:33 PM, Laurent Vivier wrote:
> 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 <dgilbert@redhat.com>
>>> Co-developed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
>>> ---
>>>    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).

Yes you are correct, I didn't check this was a migrated enum.

Regards,

Phil.