In message <[email protected]>,
John Baldwin ([email protected]) wrote:
[snip]
>
> Ah, uart_puc_probe() always uses the 'uart_ns8250_class' uart driver which
> is defined in uart_dev_ns8250.c. ns8250_bus_probe() is what you want to
> instrument I think.
ns8250_bus_probe() is called twice for each of the working devices as
follows:
UART2:
------
ns8250_bus_probe:: entry
ns8250_probe::uart_getreg REG_IIR = 1
ns8250_probe::uart_getreg REG_MCR = 0
ns8250_bus_probe:: exit
...
ns8250_bus_probe:: entry
ns8250_probe::uart_getreg REG_IIR = 193
ns8250_probe::uart_getreg REG_MCR = 8
ns8250_bus_probe:: exit
UART3
-----
ns8250_bus_probe:: entry
ns8250_probe::uart_getreg REG_IIR = 1
ns8250_probe::uart_getreg REG_MCR = 0
ns8250_bus_probe:: exit
...
ns8250_bus_probe:: entry
ns8250_probe::uart_getreg REG_IIR = 193
ns8250_probe::uart_getreg REG_MCR = 8
ns8250_bus_probe:: exit
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'?
Many thanks.
Cheers,
Nick
--
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hardware
To unsubscribe, send any mail to "[email protected]"
