tls@ wrote:
> On Fri, Apr 12, 2024 at 09:13:17AM -0400, Thor Lancelot Simon wrote:
> > On Sat, Apr 06, 2024 at 11:56:27PM +0900, Izumi Tsutsui wrote:
> > >
> > > I'd like to add new APIs to use wskbd(4) input on non-wsdisplay
> > > tty devices, especially news68k that can use a putchar function
> > > provided by firmware PROM as a kernel console device.
> >
> > Wouldn't a tty be a better abstraction for this? Lots of minicomputers
> > had incredibly dumb serial consoles.
>
> I think the above is not clear. To rephrase my question: what is the
> wscons layer actually adding here? Would it not be simpler to interface
> at the tty layer instead?
- The tty layer requires both getchar() and putchar().
- For a glass console, completely different two drivers are necessary,
i.e. keyboard driver for getchar() and display driver for putchar().
- On news68k, it's not easy to implement framebuffer driver due to
lack of information, but we can use a putchar() function provided
by a NEWS PROM firmware because it also supports VT emulation.
- On the other hand, we cannot use getchar() function provided by a
NEWS PROM firmware for useland because it uses busy loop to wait
keyboard input. But we already has a wskbd driver for NEWS machines.
- So I would like propose adding APIs "to use wskbd driver just for
keyboard inputs" for non-wscons(4) tty drivers
See sys/arch/sun3/dev/kd.c for another example that use
"PROM function for putchar() to display and
sys/dev/sun/kbd.c via zs(4) for getchar() from keyboard".
https://github.com/NetBSD/src/blob/6053b8d/sys/arch/sun3/dev/kd.c
---
static void
kdstart(struct tty *tp)
{
struct clist *cl;
int s1, s2;
s1 = splsoftclock();
s2 = spltty();
if (tp->t_state & (TS_BUSY|TS_TTSTOP|TS_TIMEOUT))
goto out;
cl = >t_outq;
if (ttypull(tp)) {
if (kd_is_console) {
tp->t_state |= TS_BUSY;
if ((s1 & PSL_IPL) == 0) {
/* called at level zero - update screen now. */
splx(s2);
kd_putfb(tp);
[...]
}
[...]
/*
* Put text on the screen using the PROM monitor.
* This can take a while, so to avoid missing
* interrupts, this is called at splsoftclock.
*/
static void
kd_putfb(struct tty *tp)
{
char buf[PUT_WSIZE];
struct clist *cl = >t_outq;
char *p, *end;
int len;
while ((len = q_to_b(cl, buf, PUT_WSIZE-1)) > 0) {
/* PROM will barf if high bits are set. */
p = buf;
end = buf + len;
while (p < end)
*p++ &= 0x7f;
(romVectorPtr->fbWriteStr)(buf, len);
}
}
[...]
/*
* Our "interrupt" routine for input. This is called by
* the keyboard driver (dev/sun/kbd.c) at spltty.
*/
void
kd_cons_input(int c)
{
struct kd_softc *kd = _softc;
struct tty *tp;
/* XXX: Make sure the device is open. */
tp = kd->kd_tty;
if (tp == NULL)
return;
if ((tp->t_state & TS_ISOPEN) == 0)
return;
(*tp->t_linesw->l_rint)(c, tp);
}
---
sys/arch/news68k/news68k/romcons.c has the similar implementation:
https://github.com/tsutsui/netbsd-src/blob/c74b64a/sys/arch/news68k/news68k/romcons.c
---
static void
romcons_start(struct tty *tp)
{
int s, len;
uint8_t buf[BURSTLEN];
s = spltty();
if (tp->t_state & (TS_TIMEOUT | TS_BUSY | TS_TTSTOP)) {
splx(s);
return;
}
tp->t_state |= TS_BUSY;
splx(s);
len = q_to_b(>t_outq, buf, BURSTLEN);
s = splhigh();
rom_write(1, buf, len);
splx(s);
s = spltty();
tp->t_state &= ~TS_BUSY;
if (ttypull(tp)) {
tp->t_state |= TS_TIMEOUT;
callout_schedule(>t_rstrt_ch, 1);
}
splx(s);
}
[...]
#if NWSKBD > 0
static void
romcons_kbdinput(device_t self, int ks)
{
struct romcons_softc *sc = device_private(self);
struct tty *tp;
KASSERT(sc != NULL);
tp = sc->sc_tty;
if (tp && (tp->t_state & TS_ISOPEN))
(*tp->t_linesw->l_rint)(ks, tp);
}
#endif
---
Izumi Tsutsui
