Date: Thu, 26 May 2011 21:22:01 +0100 From: "N.J. Mann" <njm@njm.me.uk> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-hardware@freebsd.org, Marcel Moolenaar <marcel@xcllnt.net> Subject: Re: Sunix 4056A PCI 4 port RS-232 card - only 2 ports configured Message-ID: <20110526202201.GA29605@titania.njm.me.uk> In-Reply-To: <201105261139.16839.jhb@freebsd.org> References: <20110522110002.GB91694@titania.njm.me.uk> <803C09E5-8E10-4289-A8B3-952E8A72C7A1@xcllnt.net> <20110526134211.GB9481@titania.njm.me.uk> <201105261139.16839.jhb@freebsd.org>
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In message <201105261139.16839.jhb@freebsd.org>,
John Baldwin (jhb@freebsd.org) wrote:
> On Thursday, May 26, 2011 9:42:11 am N.J. Mann wrote:
> > Hi Marcel,
> >
> >
> > In message <803C09E5-8E10-4289-A8B3-952E8A72C7A1@xcllnt.net>,
> > Marcel Moolenaar (marcel@xcllnt.net) wrote:
> > >
> > > On May 25, 2011, at 6:46 AM, John Baldwin wrote:
> > >
> > > *snip*
> > >
> > > >> For the two devices that fail, ns8250_bus_probe() fails on the first
> > > >> call:
> > > >>
> > > >> UART4
> > > >> -----
> > > >> ns8250_bus_probe:: entry
> > > >> ns8250_probe::uart_getreg REG_IIR = 1
> > > >> ns8250_probe::uart_getreg REG_MCR = 64
> > > >> ns8250_bus_probe::ns8250_probe returned 6
> > > >>
> > > >> UART5
> > > >> -----
> > > >> ns8250_bus_probe:: entry
> > > >> ns8250_probe::uart_getreg REG_IIR = 1
> > > >> ns8250_probe::uart_getreg REG_MCR = 64
> > > >> ns8250_bus_probe::ns8250_probe returned 6
> > > >>
> > > >> The value returned for the read of REG_MCR is 64, or 0x40, which causes
> > > >> the premature exit:
> > > >>
> > > >> static int
> > > >> ns8250_probe(struct uart_bas *bas)
> > > >> {
> > > >> u_char val;
> > > >>
> > > >> /* Check known 0 bits that don't depend on DLAB. */
> > > >> val = uart_getreg(bas, REG_IIR);
> > > >> if (val & 0x30)
> > > >> return (ENXIO);
> > > >> val = uart_getreg(bas, REG_MCR);
> > > >> if (val & 0xe0)
> > > >> return (ENXIO);
> > > >>
> > > >> return (0);
> > > >> }
> > > >>
> > > >> Do you need to know the contents of 'bas'?
> > > >
> > > > This goes beyond my level of knowledge. I've cc'd Marcel (author of
> uart) who
> > > > can hopefully help with this more.
> > >
> > > The ns8250 family of UARTs typically have bits 5, 6 and 7 of the
> > > MCR register reserved and thus hardwired to 0. The probe function
> > > checks for that to make sure that the hardware looks enough like
> > > a UART that we can claim it without hosing the box.
> > >
> > > That said: newer chips in the family, like the ST16C850/XR16C850,
> > > have given those bits a function:
> > > bit 5 - Xon-Any enable
> > > bit 6 - Infrared enable
> > > bit 7 - Clock pre-scaler
> > >
> > > It's unclear to me whether those bits are consistently defined
> > > across the different implementations (for some reason I think
> > > not) and it's also unclear to me whether the device will work
> > > correctly with FreeBSD if we simply ignore those bits (again I
> > > don't think this is always the case).
> > >
> > > I think the first order of business from an architectural point
> > > of view is to determine how much value register probing still has
> > > on modern hardware. In the good old days, this was needed. If
> > > we think it's not really needed anymore, then it makes sense to
> > > loosen the grip so to speak.
> > >
> > > For you, the first thing is to see whether the UART ports work
> > > if you tweak the probe functions, like so:
> > >
> > > Index: uart_dev_ns8250.c
> > > ===================================================================
> > > --- uart_dev_ns8250.c (revision 222217)
> > > +++ uart_dev_ns8250.c (working copy)
> > > @@ -243,7 +243,7 @@
> > > if (val & 0x30)
> > > return (ENXIO);
> > > val = uart_getreg(bas, REG_MCR);
> > > - if (val & 0xe0)
> > > + if (val & 0xa0)
> > > return (ENXIO);
> > >
> > > return (0);
> >
> > I tried this and the result is that ports 3 and 4 now attach okay.
> > However, the baud rate of these two is wrong. If I select 9600 they
> > actually send and receive at 1200, i.e. eight times slower. The speed
> > setting for the first two ports is correct. (I checked all four ports at
> > 9600, 38400 and 115200.)
>
> Ah, there are other reports of this:
>
> http://lists.freebsd.org/pipermail/freebsd-stable/2010-April/056533.html
>
> I think this patch should fix the timing issue:
>
> Index: pucdata.c
> ===================================================================
> --- pucdata.c (revision 222285)
> +++ pucdata.c (working copy)
> @@ -1292,6 +1292,12 @@ puc_config_timedia(struct puc_softc *sc, enum puc_
> uint16_t subdev;
>
> switch (cmd) {
> + case PUC_CFG_GET_CLOCK:
> + if (port < 2)
> + *res = DEFAULT_RCLK * 8;
> + else
> + *res = DEFAULT_RCLK;
> + return (0);
> case PUC_CFG_GET_DESC:
> snprintf(desc, sizeof(desc),
> "Timedia technology %d Port Serial", (int)sc->sc_cfg_data);
>
Yes, that fixed it. All ports are working correctly now.
Many thanks.
Cheers,
Nick.
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