Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 570d2910 authored by Jon Medhurst's avatar Jon Medhurst Committed by Greg Kroah-Hartman
Browse files

serial: amba-pl011: preseserve hardware settings during initialisation 



During initialisation, a UART may already be in use for a console, so
take care to preserve things like baud rate and data format to avoid
corrupting console output.

Signed-off-by: default avatarJon Medhurst <tixy@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b60f2f66

drivers/tty/serial/amba-pl011.c

+12 −2
Original line number Diff line number Diff line
@@ -1529,7 +1529,7 @@ static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h) 
static int pl011_startup(struct uart_port *port)

{

	struct uart_amba_port *uap = (struct uart_amba_port *)port;

	unsigned int cr;

	unsigned int cr, lcr_h, fbrd, ibrd;

	int retval;



	retval = pl011_hwinit(port);
@@ -1548,10 +1548,16 @@ static int pl011_startup(struct uart_port *port) 
	writew(uap->vendor->ifls, uap->port.membase + UART011_IFLS);



	/*

	 * Provoke TX FIFO interrupt into asserting.

	 * Provoke TX FIFO interrupt into asserting. Taking care to preserve

	 * baud rate and data format specified by FBRD, IBRD and LCRH as the

	 * UART may already be in use as a console.

	 */

	spin_lock_irq(&uap->port.lock);



	fbrd = readw(uap->port.membase + UART011_FBRD);

	ibrd = readw(uap->port.membase + UART011_IBRD);

	lcr_h = readw(uap->port.membase + uap->lcrh_rx);



	cr = UART01x_CR_UARTEN | UART011_CR_TXE | UART011_CR_LBE;

	writew(cr, uap->port.membase + UART011_CR);

	writew(0, uap->port.membase + UART011_FBRD);
@@ -1561,6 +1567,10 @@ static int pl011_startup(struct uart_port *port) 
	while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_BUSY)

		barrier();



	writew(fbrd, uap->port.membase + UART011_FBRD);

	writew(ibrd, uap->port.membase + UART011_IBRD);

	pl011_write_lcr_h(uap, lcr_h);



	/* restore RTS and DTR */

	cr = uap->old_cr & (UART011_CR_RTS | UART011_CR_DTR);

	cr |= UART01x_CR_UARTEN | UART011_CR_RXE | UART011_CR_TXE;