linux-kernel - [PATCH v2 7/9] MIPS: debug_ll: Implement support for AR933X uarts

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Message-Id: <20240326-mips_debug_ll-v2-7-b64abc76f2a1@flygoat.com>
Date: Tue, 26 Mar 2024 20:35:39 +0000
From: Jiaxun Yang <jiaxun.yang@...goat.com>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jiaxun Yang <jiaxun.yang@...goat.com>
Subject: [PATCH v2 7/9] MIPS: debug_ll: Implement support for AR933X uarts

Implement support for AR933X uarts which has it's own register
definition.

Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
---
 arch/mips/Kconfig.debug          |  9 +++++++++
 arch/mips/include/debug/ar933x.S | 41 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index aef116058654..a6687c503c34 100644
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -265,6 +265,14 @@ choice
 		  Say Y here if you want kernel low-level debugging support
 		  on uart of alchemy SoCs.
 
+	config DEBUG_AR933X_UART
+		bool "Kernel low-level debugging messages via Alchemy UART"
+		depends on MIPS_ALCHEMY
+		select DEBUG_LL_UART
+		help
+		  Say Y here if you want kernel low-level debugging support
+		  on uart of AR933X SoCs.
+
 endchoice
 
 config DEBUG_LL_INCLUDE
@@ -303,6 +311,7 @@ config DEBUG_UART_PHYS
 	default 0x1fe00000 if DEBUG_LOONGSON2K_UART
 	default 0x10030000 if DEBUG_INGENIC_UART
 	default 0x11100000 if DEBUG_ALCHEMY_UART
+	default 0x18020000 if DEBUG_AR933X_UART
 	help
 	  This is the physical base address of the debug UART. It must be
 	  accessible from unmapped kernel space (i.e. KSEG1 for 32bit kernels
diff --git a/arch/mips/include/debug/ar933x.S b/arch/mips/include/debug/ar933x.S
new file mode 100644
index 000000000000..1a0449082080
--- /dev/null
+++ b/arch/mips/include/debug/ar933x.S
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023, Jiaxun Yang <jiaxun.yang@...goat.com>
+ * MIPS Low level debug include file for ar933x UART
+ */
+
+#include <asm/addrspace.h>
+#include <asm/asm.h>
+#include <asm/mach-ath79/ar933x_uart.h>
+
+#define DEBUG_LL_UART
+
+#define UART_BASE	CKSEG1ADDR(CONFIG_DEBUG_UART_PHYS)
+
+# define UART_L		lw
+# define UART_S		sw
+
+		.macro	addruart,rd,rx
+		PTR_LA	\rd, UART_BASE
+		.endm
+
+		.macro	senduart,rd,rx
+		UART_S   \rd, AR933X_UART_DATA_REG(\rx)
+		.endm
+
+        /* CTS and RDY are handled by AR933X_UART_DATA_TX_CSR as well */
+		.macro	busyuart,rd,rx
+1002:
+		UART_L	\rd, AR933X_UART_DATA_REG(\rx)
+		andi	\rd, \rd, (AR933X_UART_DATA_TX_CSR)
+		xori	\rd, (AR933X_UART_DATA_TX_CSR)
+		bnez	\rd, 1002b
+		.endm
+
+		.macro	waituarttxrdy,rd,rx
+        busyuart \rd, \rx
+		.endm
+
+		.macro	waituartcts,rd,rx
+        busyuart \rd, \rx
+		.endm

-- 
2.34.1