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authorManfred Huber <man.huber@arcor.de>2013-03-29 02:52:36 +0000
committerTom Rini <trini@ti.com>2013-04-08 11:29:05 -0400
commitfd2aeac5606f8c706be5e07bead790c6cdee0f23 (patch)
tree4607f0485dbd0a8bf0fb4233584886eb9a04e06e
parent5aa014d613c561fb2e124acd60e4f6a34df17c21 (diff)
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omap3_beagle: Flush UART3 xmit on enable if TEMT is broken
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>
-rw-r--r--README8
-rw-r--r--drivers/serial/ns16550.c18
-rw-r--r--include/configs/igep00x0.h3
3 files changed, 16 insertions, 13 deletions
diff --git a/README b/README
index a35ef31..5c5cd18 100644
--- a/README
+++ b/README
@@ -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
diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index ed4e6b3..7f013ab 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -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)) || \
diff --git a/include/configs/igep00x0.h b/include/configs/igep00x0.h
index 849fb16..1d8090b 100644
--- a/include/configs/igep00x0.h
+++ b/include/configs/igep00x0.h
@@ -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