From 29bbb2a90fcdd46d9f12746deac4718082df325a Mon Sep 17 00:00:00 2001 From: Stafford Horne Date: Sun, 15 May 2022 13:33:14 +0900 Subject: [PATCH] openrisc: Add support for liteuart emergency printing 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 --- 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 7bfa6e4..21db505 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) -- 2.7.4