rockchip: add early uart driver

add early uart driver so we can print debug message in
SPL stage

Signed-off-by: Lin Huang <hl@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>

2 files changed, 64 insertions, 0 deletions

diff --git a/arch/arm/mach-rockchip/Makefile b/arch/arm/mach-rockchip/Makefile
index 902235b867..a29675ddf1 100644
--- a/arch/arm/mach-rockchip/Makefile
+++ b/arch/arm/mach-rockchip/Makefile
@@ -10,5 +10,6 @@ else
 obj-y += board.o
 endif
 obj-y += rk_timer.o
+obj-y += rk_early_print.o
 obj-$(CONFIG_$(SPL_)ROCKCHIP_COMMON) += common.o
 obj-$(CONFIG_ROCKCHIP_RK3288) += rk3288/
diff --git a/arch/arm/mach-rockchip/rk_early_print.c b/arch/arm/mach-rockchip/rk_early_print.c
new file mode 100644
index 0000000000..a1c14b0210
--- /dev/null
+++ b/arch/arm/mach-rockchip/rk_early_print.c
@@ -0,0 +1,63 @@
+/*
+ * (C) Copyright 2015 Rockchip Electronics Co., Ltd
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <asm/io.h>
+#include <asm/arch/uart.h>
+#include <common.h>
+
+static struct rk_uart *uart_ptr;
+
+static void uart_wrtie_byte(char byte)
+{
+	writel(byte, &uart_ptr->rbr);
+	while (!(readl(&uart_ptr->lsr) & 0x40))
+		;
+}
+
+void print(char *s)
+{
+	while (*s) {
+		if (*s == '\n')
+			uart_wrtie_byte('\r');
+	    uart_wrtie_byte(*s);
+	    s++;
+	}
+}
+
+void print_hex(unsigned int n)
+{
+	int i;
+	int temp;
+
+	uart_wrtie_byte('0');
+	uart_wrtie_byte('x');
+
+	for (i = 8; i > 0; i--) {
+		temp = (n >> (i - 1) * 4) & 0x0f;
+		if (temp < 10)
+			uart_wrtie_byte((char)(temp + '0'));
+		else
+			uart_wrtie_byte((char)(temp - 10 + 'a'));
+	}
+	uart_wrtie_byte('\n');
+	uart_wrtie_byte('\r');
+}
+
+/*
+ * TODO: since rk3036 only 4K sram to use in SPL, for saving space,
+ * we implement uart driver this way, we should convert this to use
+ * ns16550 driver in future, which support DEBUG_UART in the standard way
+ */
+void rk_uart_init(void *base)
+{
+	uart_ptr = (struct rk_uart *)base;
+	writel(0x83, &uart_ptr->lcr);
+	writel(0x0d, &uart_ptr->rbr);
+	writel(0x03, &uart_ptr->lcr);
+
+	/* fifo enable, sfe is shadow register of FCR[0] */
+	writel(0x01, &uart_ptr->sfe);
+}