ARM: uniphier: support Debug UART

For ARM32 architecture, CONFIG_DEBUG_LL is available for early
low-level debugging (and actually UniPhier 32bit SoCs use it), but
ARM64 architecture does not support it.  Instead, CONFIG_DEBUG_UART
is available as an architecture-independent debug facility.

This commit supports it on all the UniPhier SoCs (including the new
ARMv8 SoCs), which is very useful for new SoC bringups.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/arch/arm/mach-uniphier/debug-uart/debug-uart-pxs2.c b/arch/arm/mach-uniphier/debug-uart/debug-uart-pxs2.c
new file mode 100644
index 0000000000..22a200a5d6
--- /dev/null
+++ b/arch/arm/mach-uniphier/debug-uart/debug-uart-pxs2.c
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2016 Masahiro Yamada <yamada.masahiro@socionext.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <config.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+
+#include "../sc-regs.h"
+#include "../sg-regs.h"
+#include "debug-uart.h"
+
+#define UNIPHIER_PXS2_UART_CLK		88888888
+
+unsigned int uniphier_pxs2_debug_uart_init(void)
+{
+	u32 tmp;
+
+	sg_set_iectrl(0);
+	sg_set_pinsel(217, 8, 8, 4);	/* TXD0 -> TXD0 */
+	sg_set_pinsel(115, 8, 8, 4);	/* TXD1 -> TXD1 */
+	sg_set_pinsel(113, 8, 8, 4);	/* TXD2 -> TXD2 */
+	sg_set_pinsel(219, 8, 8, 4);	/* TXD3 -> TXD3 */
+
+	tmp = readl(SC_CLKCTRL);
+	tmp |= SC_CLKCTRL_CEN_PERI;
+	writel(tmp, SC_CLKCTRL);
+
+	return DIV_ROUND_CLOSEST(UNIPHIER_PXS2_UART_CLK, 16 * CONFIG_BAUDRATE);
+}