ARM: UniPhier: add UART initialization routine for low-level debug

The low-level debugging functions are useful to debug the early boot
stage where the full UART driver is not available.

UniPhier SoCs need to initialize the UART port 0 to use this feature.
The initialization routine is called at the very entry of the
lowlevel_init().

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/uniphier/ph1-pro4/lowlevel_debug.S b/arch/arm/cpu/armv7/uniphier/ph1-pro4/lowlevel_debug.S
new file mode 100644
index 0000000000..a793b7c118
--- /dev/null
+++ b/arch/arm/cpu/armv7/uniphier/ph1-pro4/lowlevel_debug.S
@@ -0,0 +1,39 @@
+/*
+ * On-chip UART initializaion for low-level debugging
+ *
+ * Copyright (C) 2014 Panasonic Corporation
+ *   Author: Masahiro Yamada <yamada.m@jp.panasonic.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <linux/linkage.h>
+#include <asm/arch/sc-regs.h>
+#include <asm/arch/sg-regs.h>
+
+#define UART_CLK		73728000
+#include <asm/arch/debug-uart.S>
+
+ENTRY(setup_lowlevel_debug)
+		ldr		r0, =SC_CLKCTRL
+		ldr		r1, [r0]
+		orr		r1, r1, #SC_CLKCTRL_CLK_PERI
+		str		r1, [r0]
+
+		init_debug_uart	r0, r1, r2
+
+		/* UART Port 0 */
+		set_pinsel	127, 0, r0, r1
+		set_pinsel	128, 0, r0, r1
+
+		ldr		r0, =SG_LOADPINCTRL
+		mov		r1, #1
+		str		r1, [r0]
+
+		ldr		r0, =SG_IECTRL
+		ldr		r1, [r0]
+		orr		r1, r1, #1
+		str		r1, [r0]
+
+		mov		pc, lr
+ENDPROC(setup_lowlevel_debug)