diff options
Diffstat (limited to 'sys/dev/uart/uart_dev_ns8250.c')
| -rw-r--r-- | sys/dev/uart/uart_dev_ns8250.c | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/sys/dev/uart/uart_dev_ns8250.c b/sys/dev/uart/uart_dev_ns8250.c index 31b1aba..47a61bf 100644 --- a/sys/dev/uart/uart_dev_ns8250.c +++ b/sys/dev/uart/uart_dev_ns8250.c @@ -649,11 +649,35 @@ int ns8250_bus_param(struct uart_softc *sc, int baudrate, int databits, int stopbits, int parity) { + struct ns8250_softc *ns8250; struct uart_bas *bas; - int error; + int error, limit; + ns8250 = (struct ns8250_softc*)sc; bas = &sc->sc_bas; uart_lock(sc->sc_hwmtx); + /* + * When using DW UART with BUSY detection it is necessary to wait + * until all serial transfers are finished before manipulating the + * line control. LCR will not be affected when UART is busy. + */ + if (ns8250->busy_detect != 0) { + /* + * Pick an arbitrary high limit to avoid getting stuck in + * an infinite loop in case when the hardware is broken. + */ + limit = 10 * 1024; + while (((uart_getreg(bas, DW_REG_USR) & USR_BUSY) != 0) && + --limit) + DELAY(4); + + if (limit <= 0) { + /* UART appears to be stuck */ + uart_unlock(sc->sc_hwmtx); + return (EIO); + } + } + error = ns8250_param(bas, baudrate, databits, stopbits, parity); uart_unlock(sc->sc_hwmtx); return (error); |
