[PATCH v1 1/2] arm: npcm: add low-level debug support for NPCM7XX

[Brendan Higgins]

Enable low-level debug support for Nuvoton NPCM7XX family by adding the
debug port definitions for the SoC.

Signed-off-by: Brendan Higgins <brendanhiggins at google.com>
---
 arch/arm/Kconfig.debug           | 11 +++++++++++
 arch/arm/include/debug/npcm7xx.S | 30 ++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100644 arch/arm/include/debug/npcm7xx.S

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index 447629d89884..d8f925cb8872 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -595,6 +595,12 @@ choice
 		  Say Y here if you want kernel low-level debugging support
 		  on Hilscher NetX based platforms.
 
+	config DEBUG_NPCM7XX_UART
+		bool "Kernel low-level debugging messages via Nuvoton NPCMx50 UART"
+		help
+		  Say Y here if you want kernel low-level debugging support
+		  on Nuvoton based platforms.
+
 	config DEBUG_NOMADIK_UART
 		bool "Kernel low-level debugging messages via NOMADIK UART"
 		depends on ARCH_NOMADIK
@@ -1444,6 +1450,7 @@ config DEBUG_LL_INCLUDE
 	default "debug/ks8695.S" if DEBUG_KS8695_UART
 	default "debug/msm.S" if DEBUG_QCOM_UARTDM
 	default "debug/netx.S" if DEBUG_NETX_UART
+	default "debug/npcm7xx.S" if DEBUG_NPCM7XX_UART
 	default "debug/omap2plus.S" if DEBUG_OMAP2PLUS_UART
 	default "debug/renesas-scif.S" if DEBUG_R7S72100_SCIF2
 	default "debug/renesas-scif.S" if DEBUG_RCAR_GEN1_SCIF0
@@ -1481,6 +1488,7 @@ config DEBUG_UART_8250
 config DEBUG_UART_PHYS
 	hex "Physical base address of debug UART"
 	default 0x00100a00 if DEBUG_NETX_UART
+	default 0xf0004000 if DEBUG_NPCM7XX_UART
 	default 0x01c20000 if DEBUG_DAVINCI_DMx_UART0
 	default 0x01c28000 if DEBUG_SUNXI_UART0
 	default 0x01c28400 if DEBUG_SUNXI_UART1
@@ -1589,6 +1597,7 @@ config DEBUG_UART_PHYS
 		DEBUG_LL_UART_EFM32 || \
 		DEBUG_UART_8250 || DEBUG_UART_PL01X || DEBUG_MESON_UARTAO || \
 		DEBUG_NETX_UART || \
+		DEBUG_NPCM7XX_UART || \
 		DEBUG_QCOM_UARTDM || DEBUG_R7S72100_SCIF2 || \
 		DEBUG_RCAR_GEN1_SCIF0 || DEBUG_RCAR_GEN1_SCIF2 || \
 		DEBUG_RCAR_GEN2_SCIF0 || DEBUG_RCAR_GEN2_SCIF2 || \
@@ -1605,6 +1614,7 @@ config DEBUG_UART_VIRT
 	default 0xc8821000 if DEBUG_RV1108_UART1
 	default 0xc8912000 if DEBUG_RV1108_UART0
 	default 0xe0000a00 if DEBUG_NETX_UART
+	default 0xf0001000 if DEBUG_NPCM7XX_UART
 	default 0xe0010fe0 if ARCH_RPC
 	default 0xf0000be0 if ARCH_EBSA110
 	default 0xf0010000 if DEBUG_ASM9260_UART
@@ -1695,6 +1705,7 @@ config DEBUG_UART_VIRT
 	depends on DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || \
 		DEBUG_UART_8250 || DEBUG_UART_PL01X || DEBUG_MESON_UARTAO || \
 		DEBUG_NETX_UART || \
+		DEBUG_NPCM7XX_UART || \
 		DEBUG_QCOM_UARTDM || DEBUG_S3C24XX_UART || \
 		DEBUG_S3C64XX_UART || \
 		DEBUG_BCM63XX_UART || DEBUG_ASM9260_UART || \
diff --git a/arch/arm/include/debug/npcm7xx.S b/arch/arm/include/debug/npcm7xx.S
new file mode 100644
index 000000000000..d08e14e73d79
--- /dev/null
+++ b/arch/arm/include/debug/npcm7xx.S
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright 2018 Google, Inc.
+// This is heavily based on arch/arm/include/debug/at91.S
+
+#define NPCM7XX_SR	(0x14)	/* Status Register */
+#define NPCM7XX_THR	(0x00)	/* Transmitter Holding Register */
+#define NPCM7XX_TXRDY	(1 << 6)	/* Transmitter Ready */
+#define NPCM7XX_TXEMPTY	(1 << 6)	/* Transmitter Empty */
+
+	.macro	addruart, rp, rv, tmp
+	ldr	\rp, =CONFIG_DEBUG_UART_PHYS	@ System peripherals (phys)
+	ldr	\rv, =CONFIG_DEBUG_UART_VIRT	@ System peripherals (virt)
+	.endm
+
+	.macro	senduart,rd,rx
+	strb	\rd, [\rx, #(NPCM7XX_THR)]	@ Write to Transmit Holding Reg
+	.endm
+
+	.macro	waituart,rd,rx
+1001:	ldr	\rd, [\rx, #(NPCM7XX_SR)]	@ Read Status Register
+	tst	\rd, #NPCM7XX_TXRDY		@ TXRDY = 1 when ready to tx
+	beq	1001b
+	.endm
+
+	.macro	busyuart,rd,rx
+1001:	ldr	\rd, [\rx, #(NPCM7XX_SR)]	@ Read Status Register
+	tst	\rd, #NPCM7XX_TXEMPTY		@ TXEMPTY = 1 when tx complete
+	beq	1001b
+	.endm
+
-- 
2.16.0.rc1.238.g530d649a79-goog