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>

arch/arm/cpu/armv7/uniphier/lowlevel_init.S

@@ -26,6 +26,10 @@ ENTRY(lowlevel_init)
 	orr	r0, r0, #(CR_C | CR_M)		@ enable MMU and Dcache
 	mcr	p15, 0, r0, c1, c0, 0
 
+#ifdef CONFIG_DEBUG_LL
+	bl	setup_lowlevel_debug
+#endif
+
 	/*
 	 * Now we are using the page table embedded in the Boot ROM.
 	 * It is not handy since it is not a straight mapped table for sLD3.

arch/arm/cpu/armv7/uniphier/ph1-ld4/Makefile

@@ -5,6 +5,7 @@
 obj-$(CONFIG_DISPLAY_BOARDINFO) += board_info.o
 obj-$(if $(CONFIG_OF_CONTROL),,y) += platdevice.o
 obj-y += boot-mode.o
+obj-$(CONFIG_DEBUG_LL) += lowlevel_debug.o
 obj-$(CONFIG_SOC_INIT) += bcu_init.o sbc_init.o sg_init.o pll_init.o \
 								clkrst_init.o
 obj-$(CONFIG_BOARD_POSTCLK_INIT) += pinctrl.o

arch/arm/cpu/armv7/uniphier/ph1-ld4/lowlevel_debug.S

@@ -0,0 +1,29 @@
+/*
+ * 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/sg-regs.h>
+
+#define UART_CLK		36864000
+#include <asm/arch/debug-uart.S>
+
+ENTRY(setup_lowlevel_debug)
+		init_debug_uart	r0, r1, r2
+
+		/* UART Port 0 */
+		set_pinsel	85, 1, r0, r1
+		set_pinsel	88, 1, r0, r1
+
+		ldr		r0, =SG_IECTRL
+		ldr		r1, [r0]
+		orr		r1, r1, #1
+		str		r1, [r0]
+
+		mov		pc, lr
+ENDPROC(setup_lowlevel_debug)

arch/arm/cpu/armv7/uniphier/ph1-pro4/Makefile

@@ -5,6 +5,7 @@
 obj-$(CONFIG_DISPLAY_BOARDINFO) += board_info.o
 obj-$(if $(CONFIG_OF_CONTROL),,y) += platdevice.o
 obj-y += boot-mode.o
+obj-$(CONFIG_DEBUG_LL) += lowlevel_debug.o
 obj-$(CONFIG_SOC_INIT) += sbc_init.o sg_init.o pll_init.o clkrst_init.o
 obj-$(CONFIG_BOARD_POSTCLK_INIT) += pinctrl.o
 obj-$(CONFIG_DRAM_INIT) += pll_spectrum.o umc_init.o ddrphy_init.o

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)

arch/arm/cpu/armv7/uniphier/ph1-sld8/Makefile

@@ -5,6 +5,7 @@
 obj-$(CONFIG_DISPLAY_BOARDINFO) += board_info.o
 obj-$(if $(CONFIG_OF_CONTROL),,y) += platdevice.o
 obj-y += boot-mode.o
+obj-$(CONFIG_DEBUG_LL) += lowlevel_debug.o
 obj-$(CONFIG_SOC_INIT) += bcu_init.o sbc_init.o sg_init.o pll_init.o \
 								clkrst_init.o
 obj-$(CONFIG_BOARD_POSTCLK_INIT) += pinctrl.o

arch/arm/cpu/armv7/uniphier/ph1-sld8/lowlevel_debug.S

@@ -0,0 +1,29 @@
+/*
+ * 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/sg-regs.h>
+
+#define UART_CLK		80000000
+#include <asm/arch/debug-uart.S>
+
+ENTRY(setup_lowlevel_debug)
+		init_debug_uart	r0, r1, r2
+
+		/* UART Port 0 */
+		set_pinsel	70, 3, r0, r1
+		set_pinsel	71, 3, r0, r1
+
+		ldr		r0, =SG_IECTRL
+		ldr		r1, [r0]
+		orr		r1, r1, #1
+		str		r1, [r0]
+
+		mov		pc, lr
+ENDPROC(setup_lowlevel_debug)

arch/arm/include/asm/arch-uniphier/debug-uart.S

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2014 Panasonic Corporation
+ *   Author: Masahiro Yamada <yamada.m@jp.panasonic.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <linux/serial_reg.h>
+
+#if !defined(CONFIG_DEBUG_SEMIHOSTING)
+#include CONFIG_DEBUG_LL_INCLUDE
+#endif
+
+#define BAUDRATE		115200
+#define DIV_ROUND(x, d)		(((x) + ((d) / 2)) / (d))
+#define DIVISOR			DIV_ROUND(UART_CLK, 16 * BAUDRATE)
+
+	.macro		init_debug_uart, ra, rb, rc
+	addruart	\ra, \rb, \rc
+	mov		\rb, #UART_LCR_WLEN8
+	strb		\rb, [\ra, #0x11]
+	ldr		\rb, =DIVISOR
+	str		\rb, [\ra, #0x24]
+	.endm