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Subject[PATCH v2 03/13] openrisc: Add support for liteuart emergency printing
Date
This patch adds support for sending emergency print output, such as
unhandled exception details, to a liteuart serial device. This is the
default device available on litex platforms.

If a developer want to use this they should update UART_BASE_ADD
to the address of liteuart.

Signed-off-by: Stafford Horne <shorne@gmail.com>
---
Changes since v1:
- Update for patch 2/12 ifdef changes

arch/openrisc/kernel/head.S | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/openrisc/kernel/head.S b/arch/openrisc/kernel/head.S
index 7bfa6e4b60c5..21db50563f97 100644
--- a/arch/openrisc/kernel/head.S
+++ b/arch/openrisc/kernel/head.S
@@ -1555,7 +1555,18 @@ ENTRY(_emergency_putc)
l.movhi r4,hi(UART_BASE_ADD)
l.ori r4,r4,lo(UART_BASE_ADD)

-#if defined(CONFIG_SERIAL_8250)
+#if defined(CONFIG_SERIAL_LITEUART)
+ /* Check OFF_TXFULL status */
+1: l.lwz r5,4(r4)
+ l.andi r5,r5,0xff
+ l.sfnei r5,0
+ l.bf 1b
+ l.nop
+
+ /* Write character */
+ l.andi r7,r7,0xff
+ l.sw 0(r4),r7
+#elif defined(CONFIG_SERIAL_8250)
/* Check UART LSR THRE (hold) bit */
l.addi r6,r0,0x20
1: l.lbz r5,5(r4)
--
2.31.1
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