| Message ID | 20210829100103.1950-4-mark.cave-ayland@ilande.co.uk |
|---|---|
| State | New |
| Headers | show |
| Series | escc: fix R_STATUS when SDLC mode is enabled | expand |
On Sun, 29 Aug 2021 at 11:04, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> wrote: > > After an SDLC "Enter hunt" command has been sent the STATUS_SYNC bit should remain > high until the flag byte has been detected. Whilst the ESCC device doesn't yet > implement SDLC mode, without this change the active low STATUS_SYNC is constantly > asserted causing the MacOS OpenTransport extension to hang on startup as it thinks > it is constantly receiving LocalTalk responses during its initial negotiation > phase. > > Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> > --- > hw/char/escc.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/hw/char/escc.c b/hw/char/escc.c > index 0f6957ba8b..eba6b45baa 100644 > --- a/hw/char/escc.c > +++ b/hw/char/escc.c > @@ -92,6 +92,7 @@ > #define W_IVEC 2 > #define W_RXCTRL 3 > #define RXCTRL_RXEN 0x01 > +#define RXCTRL_HUNT 0x10 > #define W_TXCTRL1 4 > #define TXCTRL1_PAREN 0x01 > #define TXCTRL1_PAREV 0x02 > @@ -508,7 +509,13 @@ static void escc_mem_write(void *opaque, hwaddr addr, > break; > } > break; > - case W_INTR ... W_RXCTRL: > + case W_RXCTRL: > + s->wregs[s->reg] = val; > + if (val & RXCTRL_HUNT) { > + s->rregs[R_STATUS] |= STATUS_SYNC; > + } > + break; > + case W_INTR ... W_IVEC: > case W_SYNC1 ... W_TXBUF: > case W_MISC1 ... W_CLOCK: > case W_MISC2 ... W_EXTINT: If I read the manual correctly I think strictly speaking if this is a 0->1 transition for the SYNC bit it is supposed to generate an interrupt. But I guess since we don't implement any of this stuff we can ignore that... Reviewed-by: Peter Maydell <peter.maydell@linaro.org> thanks -- PMM
diff --git a/hw/char/escc.c b/hw/char/escc.c index 0f6957ba8b..eba6b45baa 100644 --- a/hw/char/escc.c +++ b/hw/char/escc.c @@ -92,6 +92,7 @@ #define W_IVEC 2 #define W_RXCTRL 3 #define RXCTRL_RXEN 0x01 +#define RXCTRL_HUNT 0x10 #define W_TXCTRL1 4 #define TXCTRL1_PAREN 0x01 #define TXCTRL1_PAREV 0x02 @@ -508,7 +509,13 @@ static void escc_mem_write(void *opaque, hwaddr addr, break; } break; - case W_INTR ... W_RXCTRL: + case W_RXCTRL: + s->wregs[s->reg] = val; + if (val & RXCTRL_HUNT) { + s->rregs[R_STATUS] |= STATUS_SYNC; + } + break; + case W_INTR ... W_IVEC: case W_SYNC1 ... W_TXBUF: case W_MISC1 ... W_CLOCK: case W_MISC2 ... W_EXTINT:
After an SDLC "Enter hunt" command has been sent the STATUS_SYNC bit should remain high until the flag byte has been detected. Whilst the ESCC device doesn't yet implement SDLC mode, without this change the active low STATUS_SYNC is constantly asserted causing the MacOS OpenTransport extension to hang on startup as it thinks it is constantly receiving LocalTalk responses during its initial negotiation phase. Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> --- hw/char/escc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)