[PATCH v2 19/21] ARM: rpi: add debug_ll support for Raspberry Pi 4

[Ahmad Fatoum]

The mini uart (Pins 8/10) is the primary UART on the Raspberry Pi 4 and
can be set up in firmware by specifying enable_uart=1 in the config.txt.

Add a DEBUG_LL implementation to use this for early debugging.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 arch/arm/mach-bcm283x/include/mach/debug_ll.h | 20 +++++++++++++++++++
 arch/arm/mach-bcm283x/include/mach/platform.h |  1 +
 common/Kconfig                                |  7 +++++++
 3 files changed, 28 insertions(+)

diff --git a/arch/arm/mach-bcm283x/include/mach/debug_ll.h b/arch/arm/mach-bcm283x/include/mach/debug_ll.h
index db23112aa07e..fdb63b4f5a40 100644
--- a/arch/arm/mach-bcm283x/include/mach/debug_ll.h
+++ b/arch/arm/mach-bcm283x/include/mach/debug_ll.h
@@ -18,6 +18,7 @@
 #define __MACH_BCM2835_DEBUG_LL_H__
 
 #include <mach/platform.h>
+#include <io.h>
 
 #ifdef CONFIG_DEBUG_RPI1_UART
 
@@ -66,6 +67,25 @@ static inline void debug_ll_init(void)
 	debug_ll_ns16550_init(divisor);
 }
 
+#elif defined CONFIG_DEBUG_RPI4_MINI_UART
+
+static inline uint8_t debug_ll_read_reg(int reg)
+{
+	return readb(BCM2711_MINIUART_BASE + (reg << 2));
+}
+
+static inline void debug_ll_write_reg(int reg, uint8_t val)
+{
+	writeb(val, BCM2711_MINIUART_BASE + (reg << 2));
+}
+
+#include <debug_ll/ns16550.h>
+
+static inline void debug_ll_init(void)
+{
+	/* Configured by ROM */
+}
+
 #else
 
 static inline void debug_ll_init(void)
diff --git a/arch/arm/mach-bcm283x/include/mach/platform.h b/arch/arm/mach-bcm283x/include/mach/platform.h
index 6917e1f345d7..b957ac8de35e 100644
--- a/arch/arm/mach-bcm283x/include/mach/platform.h
+++ b/arch/arm/mach-bcm283x/include/mach/platform.h
@@ -34,6 +34,7 @@
 #define BCM2836_PL011_BASE 0x3f201000UL
 #define BCM2835_MINIUART_BASE 0x20215040
 #define BCM2836_MINIUART_BASE 0x3f215040UL
+#define BCM2711_MINIUART_BASE 0xfe215040UL
 
 #endif
 
diff --git a/common/Kconfig b/common/Kconfig
index f7a6a96e877c..4054bd838dec 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -1413,6 +1413,13 @@ config DEBUG_RPI3_MINI_UART
 	  Say Y here if you want low-level debugging support on
 	  RaspberryPi 3 board mini UART.
 
+config DEBUG_RPI4_MINI_UART
+	bool "RaspberryPi 4 mini UART"
+	depends on ARCH_BCM283X
+	help
+	  Say Y here if you want low-level debugging support on
+	  RaspberryPi 4 board mini UART.
+
 config DEBUG_ERIZO
 	bool "Erizo ns16550 port"
 	depends on SOC_ERIZO
-- 
2.30.2