MFC: r260889, r260890, r260911:

	r260911 | imp | 2014-01-20 10:45:36 -0700 (Mon, 20 Jan 2014) | 5 lines

	Don't lock in the generic grab just to lock again in the specific grabs.

	r260890 | imp | 2014-01-19 12:39:13 -0700 (Sun, 19 Jan 2014) | 11 lines

	Introduce grab and ungrab upcalls. When the kernel desires to grab the
	console, it calls the grab functions. These functions should turn off
	the RX interrupts, and any others that interfere. This makes mountroot
	prompt work again. If there's more generalized need other than
	prompting, many of these routines should be expanded to do those new
	things.

	Reviewed by:    bde (with reservations)

1 files changed, 35 insertions, 0 deletions

diff --git a/sys/dev/uart/uart_dev_lpc.c b/sys/dev/uart/uart_dev_lpc.c
index fc981ec..ba87a17 100644
--- a/sys/dev/uart/uart_dev_lpc.c
+++ b/sys/dev/uart/uart_dev_lpc.c
@@ -400,6 +400,8 @@ static int lpc_ns8250_bus_probe(struct uart_softc *);
 static int lpc_ns8250_bus_receive(struct uart_softc *);
 static int lpc_ns8250_bus_setsig(struct uart_softc *, int);
 static int lpc_ns8250_bus_transmit(struct uart_softc *);
+static void lpc_ns8250_bus_grab(struct uart_softc *);
+static void lpc_ns8250_bus_ungrab(struct uart_softc *);
 
 static kobj_method_t lpc_ns8250_methods[] = {
 	KOBJMETHOD(uart_attach,		lpc_ns8250_bus_attach),
@@ -413,6 +415,8 @@ static kobj_method_t lpc_ns8250_methods[] = {
 	KOBJMETHOD(uart_receive,	lpc_ns8250_bus_receive),
 	KOBJMETHOD(uart_setsig,		lpc_ns8250_bus_setsig),
 	KOBJMETHOD(uart_transmit,	lpc_ns8250_bus_transmit),
+	KOBJMETHOD(uart_grab,		lpc_ns8250_bus_grab),
+	KOBJMETHOD(uart_ungrab,		lpc_ns8250_bus_ungrab),
 	{ 0, 0 }
 };
 
@@ -889,3 +893,34 @@ lpc_ns8250_bus_transmit(struct uart_softc *sc)
 	uart_unlock(sc->sc_hwmtx);
 	return (0);
 }
+
+void
+lpc_ns8250_bus_grab(struct uart_softc *sc)
+{
+	struct uart_bas *bas = &sc->sc_bas;
+
+	/*
+	 * turn off all interrupts to enter polling mode. Leave the
+	 * saved mask alone. We'll restore whatever it was in ungrab.
+	 * All pending interupt signals are reset when IER is set to 0.
+	 */
+	uart_lock(sc->sc_hwmtx);
+	uart_setreg(bas, REG_IER, 0);
+	uart_barrier(bas);
+	uart_unlock(sc->sc_hwmtx);
+}
+
+void
+lpc_ns8250_bus_ungrab(struct uart_softc *sc)
+{
+	struct lpc_ns8250_softc *lpc_ns8250 = (struct lpc_ns8250_softc*)sc;
+	struct uart_bas *bas = &sc->sc_bas;
+
+	/*
+	 * Restore previous interrupt mask
+	 */
+	uart_lock(sc->sc_hwmtx);
+	uart_setreg(bas, REG_IER, lpc_ns8250->ier);
+	uart_barrier(bas);
+	uart_unlock(sc->sc_hwmtx);
+}