diff options
| author | Jon Medhurst <tixy@linaro.org> | 2013-12-10 10:19:00 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-17 09:35:38 -0800 |
| commit | 570d291048aecc02271884f6a5f50ad555f271a5 (patch) | |
| tree | 9d9e47b193b44c5550cbdd24b93a687d3a8b6d56 /drivers/tty | |
| parent | b60f2f66a58c43e8c928336ec72f64e72f1237ea (diff) | |
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: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/amba-pl011.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 844bfba9d0ab..182a922e1942 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -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; |