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

[Philippe Mathieu-Daudé]

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 <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).

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

Regards,

Phil.