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omap3_beagle: Flush UART3 xmit on enable if TEMT is broken

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Flush UART3 xmit on enable if TEMT is broken

On some OMAP3 devices when UART3 is configured for boot mode before SPL starts
only THRE bit is set. We have to empty the transmitter before initialization
starts. This patch avoids the use of CONFIG_SYS_NS16550_BROKEN_TEMT.

Signed-off-by: Manfred Huber <man.huber@arcor.de>
Tested-by: Javier Martinez Canillas <javier@dowhile0.org>
Tested-by: Andreas Bießmann <andreas.devel@googlemail.com>
This commit is contained in:
Manfred Huber 2013-03-29 02:52:36 +00:00 committed by Tom Rini
parent 5aa014d613
commit fd2aeac560
3 changed files with 16 additions and 13 deletions
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8
README
View File

@ -627,14 +627,6 @@ The following options need to be configured:
boot loader that has already initialized the UART. Define this
variable to flush the UART at init time.
CONFIG_SYS_NS16550_BROKEN_TEMT
16550 UART set the Transmitter Empty (TEMT) Bit when all output
has finished and the transmitter is totally empty. U-Boot waits
for this bit to be set to initialize the serial console. On some
broken platforms this bit is not set in SPL making U-Boot to
hang while waiting for TEMT. Define this option to avoid it.
- Console Interface:
Depending on board, define exactly one serial port

18
drivers/serial/ns16550.c
View File

@ -36,10 +36,24 @@
void NS16550_init(NS16550_t com_port, int baud_divisor)
{
#if (!defined(CONFIG_SYS_NS16550_BROKEN_TEMT))
#if (defined(CONFIG_SPL_BUILD) && defined(CONFIG_OMAP34XX))
/*
* On some OMAP3 devices when UART3 is configured for boot mode before
* SPL starts only THRE bit is set. We have to empty the transmitter
* before initialization starts.
*/
if ((serial_in(&com_port->lsr) & (UART_LSR_TEMT | UART_LSR_THRE))
== UART_LSR_THRE) {
serial_out(UART_LCR_DLAB, &com_port->lcr);
serial_out(baud_divisor & 0xff, &com_port->dll);
serial_out((baud_divisor >> 8) & 0xff, &com_port->dlm);
serial_out(UART_LCRVAL, &com_port->lcr);
serial_out(0, &com_port->mdr1);
}
#endif
while (!(serial_in(&com_port->lsr) & UART_LSR_TEMT))
;
#endif
serial_out(CONFIG_SYS_NS16550_IER, &com_port->ier);
#if (defined(CONFIG_OMAP) && !defined(CONFIG_OMAP3_ZOOM2)) || \

3
include/configs/igep00x0.h
View File

@ -69,9 +69,6 @@
#define CONFIG_SYS_NS16550_REG_SIZE (-4)
#define CONFIG_SYS_NS16550_CLK V_NS16550_CLK
/* define to avoid U-Boot to hang while waiting for TEMT */
#define CONFIG_SYS_NS16550_BROKEN_TEMT
/* select serial console configuration */
#define CONFIG_CONS_INDEX 3
#define CONFIG_SYS_NS16550_COM3 OMAP34XX_UART3