ARM: bcm: Support BCMBCA debug UART

The debug UART on the BCMBCA SoCs are in a different place
than on the other BCM platforms. Support this with a static
map when debugging is explicitly configured.

Right now I can only test this on BCM6846 so this is the
only compatible I list for the debug boardfile, but other
compatibles from the BCMBCA family can be added to get
LL_DEBUG support.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: William Zhang <william.zhang@broadcom.com>
Link: https://lore.kernel.org/r/20240923-bcm-arm-bcm6846-v2-1-f4a7191b501a@linaro.org
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>

Author: Linus Walleij

arch/arm/Kconfig.debug

@@ -242,6 +242,10 @@ choice
 		depends on ARCH_BCM_5301X || ARCH_BCM_NSP
 		select DEBUG_UART_8250
 
+	config DEBUG_BCMBCA
+		bool "Kernel low-level debugging on BCMBCA UART0"
+		depends on ARCH_BCMBCA
+
 	config DEBUG_BCM_HR2
 		bool "Kernel low-level debugging on Hurricane 2 UART2"
 		depends on ARCH_BCM_HR2
@@ -1526,7 +1530,7 @@ config DEBUG_LL_INCLUDE
 	default "debug/vf.S" if DEBUG_VF_UART
 	default "debug/vt8500.S" if DEBUG_VT8500_UART0
 	default "debug/zynq.S" if DEBUG_ZYNQ_UART0 || DEBUG_ZYNQ_UART1
-	default "debug/bcm63xx.S" if DEBUG_BCM63XX_UART
+	default "debug/bcm63xx.S" if DEBUG_BCM63XX_UART || DEBUG_BCMBCA
 	default "debug/digicolor.S" if DEBUG_DIGICOLOR_UA0
 	default "debug/brcmstb.S" if DEBUG_BRCMSTB_UART
 	default "mach/debug-macro.S"
@@ -1640,6 +1644,7 @@ config DEBUG_UART_PHYS
 	default 0xfe531000 if DEBUG_STIH41X_SBC_ASC1
 	default 0xfed32000 if DEBUG_STIH41X_ASC2
 	default 0xff690000 if DEBUG_RK32_UART2
+	default 0xff800640 if DEBUG_BCMBCA
 	default 0xffc02000 if DEBUG_SOCFPGA_UART0
 	default 0xffc02100 if DEBUG_SOCFPGA_ARRIA10_UART1
 	default 0xffc03000 if DEBUG_SOCFPGA_CYCLONE5_UART1
@@ -1664,7 +1669,7 @@ config DEBUG_UART_PHYS
 		DEBUG_RMOBILE_SCIFA0 || DEBUG_RMOBILE_SCIFA1 || \
 		DEBUG_RMOBILE_SCIFA4 || \
 		DEBUG_S3C64XX_UART || \
-		DEBUG_BCM63XX_UART || DEBUG_ASM9260_UART || \
+		DEBUG_BCM63XX_UART || DEBUG_BCMBCA || DEBUG_ASM9260_UART || \
 		DEBUG_DIGICOLOR_UA0 || \
 		DEBUG_AT91_UART || DEBUG_STM32_UART || \
 		DEBUG_STIH41X_ASC2 || DEBUG_STIH41X_SBC_ASC1 || \
@@ -1734,6 +1739,7 @@ config DEBUG_UART_VIRT
 	default 0xfe018000 if DEBUG_MMP_UART3
 	default 0xfe100000 if DEBUG_IMX23_UART || DEBUG_IMX28_UART
 	default 0xfe300000 if DEBUG_BCM_KONA_UART
+	default 0xfe300640 if DEBUG_BCMBCA
 	default 0xfeb00000 if DEBUG_HI3620_UART || DEBUG_HIX5HD2_UART
 	default 0xfeb24000 if DEBUG_RK3X_UART0
 	default 0xfeb26000 if DEBUG_RK3X_UART1
@@ -1765,7 +1771,7 @@ config DEBUG_UART_VIRT
 		DEBUG_UART_8250 || DEBUG_UART_PL01X || DEBUG_MESON_UARTAO || \
 		DEBUG_QCOM_UARTDM || \
 		DEBUG_S3C64XX_UART || \
-		DEBUG_BCM63XX_UART || DEBUG_ASM9260_UART || \
+		DEBUG_BCM63XX_UART || DEBUG_BCMBCA || DEBUG_ASM9260_UART || \
 		DEBUG_DIGICOLOR_UA0 || \
 		DEBUG_AT91_UART || DEBUG_STM32_UART || \
 		DEBUG_STIH41X_ASC2 || DEBUG_STIH41X_SBC_ASC1 || \

arch/arm/mach-bcm/Makefile

@@ -58,5 +58,6 @@ endif
 
 # BCMBCA
 ifeq ($(CONFIG_ARCH_BCMBCA),y)
+obj-$(CONFIG_DEBUG_BCMBCA)	+= board_bcmbca.o
 obj-$(CONFIG_SMP)		+= bcm63xx_smp.o bcm63xx_pmb.o
 endif

arch/arm/mach-bcm/board_bcmbca.c

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2024 Linus Walleij <linus.walleij@linaro.org>
+
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+
+/* This is needed for LL-debug/earlyprintk/debug-macro.S */
+static struct map_desc bcmbca_io_desc[] __initdata = {
+	{
+		.virtual = CONFIG_DEBUG_UART_VIRT,
+		.pfn = __phys_to_pfn(CONFIG_DEBUG_UART_PHYS),
+		.length = SZ_4K,
+		.type = MT_DEVICE,
+	},
+};
+
+static void __init bcmbca_map_io(void)
+{
+	iotable_init(bcmbca_io_desc, ARRAY_SIZE(bcmbca_io_desc));
+}
+
+static const char * const bcmbca_dt_compat[] = {
+	/* TODO: Add other BCMBCA SoCs here to get debug UART support */
+	"brcm,bcm6846",
+	NULL,
+};
+
+DT_MACHINE_START(BCMBCA_DT, "BCMBCA Broadband Access Processors")
+	.map_io = bcmbca_map_io,
+	.dt_compat = bcmbca_dt_compat,
+MACHINE_END