rpi: Allow using PL011 UART for RPi3/RPi4

The Broadcom 283x SoCs feature multiple UARTs: the mostly used
"Mini-UART", which is an 8250 compatible IP, and at least one PL011.
While the 8250 is usually used for serial console purposes, it suffers
from a design flaw, where its clock depends on the VPU clock, which can
change at runtime. This will reliably mess up the baud rate.
To avoid this problem, people might choose to use the PL011 UART for
the serial console, which is pin-mux'ed to the very same GPIO pins.
This can be done by adding "miniuart-bt" to the "dtoverlay=" line in
config.txt.

To prepare for this situation, use the newly gained freedom of sharing
one console_t pointer across different UART drivers, to introduce the
option of choosing the PL011 for the console.

This is for now hard-coded to choose the Mini-UART by default.
A follow-up patch will introduce automatic detection.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: I8cf2522151e09ff4ff94a6d396aec6fc4b091a05

plat/rpi/common/rpi3_common.c

@@ -14,6 +14,7 @@
 #include <bl31/interrupt_mgmt.h>
 #include <drivers/console.h>
 #include <drivers/ti/uart/uart_16550.h>
+#include <drivers/arm/pl011.h>
 #include <lib/xlat_tables/xlat_tables_v2.h>
 
 #include <rpi_hw.h>
@@ -104,6 +105,11 @@ static const mmap_region_t plat_rpi3_mmap[] = {
  ******************************************************************************/
 static console_t rpi3_console;
 
+static bool rpi3_use_mini_uart(void)
+{
+	return true;
+}
+
 void rpi3_console_init(void)
 {
 	int console_scope = CONSOLE_FLAG_BOOT;
@@ -112,10 +118,16 @@ void rpi3_console_init(void)
 	if (RPI3_RUNTIME_UART != -1)
 		console_scope |= CONSOLE_FLAG_RUNTIME;
 
-	rc = console_16550_register(PLAT_RPI_MINI_UART_BASE,
-				    0,
-				    PLAT_RPI_UART_BAUDRATE,
-				    &rpi3_console);
+	if (rpi3_use_mini_uart())
+		rc = console_16550_register(PLAT_RPI_MINI_UART_BASE,
+					    0,
+					    PLAT_RPI_UART_BAUDRATE,
+					    &rpi3_console);
+	else
+		rc = console_pl011_register(PLAT_RPI_PL011_UART_BASE,
+					    PLAT_RPI_PL011_UART_CLOCK,
+					    PLAT_RPI_UART_BAUDRATE,
+					    &rpi3_console);
 
 	if (rc == 0) {
 		/*

plat/rpi/rpi3/include/platform_def.h

@@ -250,6 +250,8 @@
  * Serial-related constants.
  */
 #define PLAT_RPI_MINI_UART_BASE		RPI3_MINI_UART_BASE
+#define PLAT_RPI_PL011_UART_BASE	RPI3_PL011_UART_BASE
+#define PLAT_RPI_PL011_UART_CLOCK	RPI3_PL011_UART_CLOCK
 #define PLAT_RPI_UART_BAUDRATE		ULL(115200)
 
 /*

plat/rpi/rpi3/include/rpi_hw.h

@@ -77,10 +77,15 @@
 #define RPI3_RNG_INT_MASK_DISABLE	U(0x1)
 
 /*
- * Serial port (called 'Mini UART' in the BCM docucmentation).
+ * Serial ports:
+ * 'Mini UART' in the BCM docucmentation is the 8250 compatible UART.
+ * There is also a PL011 UART, multiplexed to the same pins.
  */
 #define RPI3_IO_MINI_UART_OFFSET	ULL(0x00215040)
 #define RPI3_MINI_UART_BASE		(RPI_IO_BASE + RPI3_IO_MINI_UART_OFFSET)
+#define RPI3_IO_PL011_UART_OFFSET	ULL(0x00201000)
+#define RPI3_PL011_UART_BASE		(RPI_IO_BASE + RPI3_IO_PL011_UART_OFFSET)
+#define RPI3_PL011_UART_CLOCK		ULL(48000000)
 
 /*
  * GPIO controller

plat/rpi/rpi3/platform.mk

@@ -11,6 +11,7 @@ PLAT_INCLUDES		:=	-Iplat/rpi/common/include		\
 				-Iplat/rpi/rpi3/include
 
 PLAT_BL_COMMON_SOURCES	:=	drivers/ti/uart/aarch64/16550_console.S	\
+				drivers/arm/pl011/aarch64/pl011_console.S \
 				plat/rpi/common/rpi3_common.c		\
 				${XLAT_TABLES_LIB_SRCS}
 

plat/rpi/rpi4/include/platform_def.h

@@ -127,6 +127,8 @@
  * Serial-related constants.
  */
 #define PLAT_RPI_MINI_UART_BASE		RPI4_MINI_UART_BASE
+#define PLAT_RPI_PL011_UART_BASE	RPI4_PL011_UART_BASE
+#define PLAT_RPI_PL011_UART_CLOCK       RPI4_PL011_UART_CLOCK
 #define PLAT_RPI_UART_BAUDRATE          ULL(115200)
 
 /*

plat/rpi/rpi4/include/rpi_hw.h

@@ -77,10 +77,15 @@
 #define RPI3_RNG_INT_MASK_DISABLE	U(0x1)
 
 /*
- * Serial port (called 'Mini UART' in the Broadcom documentation).
+ * Serial ports:
+ * 'Mini UART' in the BCM docucmentation is the 8250 compatible UART.
+ * There is also a PL011 UART, multiplexed to the same pins.
  */
 #define RPI4_IO_MINI_UART_OFFSET	ULL(0x00215040)
 #define RPI4_MINI_UART_BASE		(RPI_IO_BASE + RPI4_IO_MINI_UART_OFFSET)
+#define RPI4_IO_PL011_UART_OFFSET	ULL(0x00201000)
+#define RPI4_PL011_UART_BASE		(RPI_IO_BASE + RPI4_IO_PL011_UART_OFFSET)
+#define RPI4_PL011_UART_CLOCK		ULL(48000000)
 
 /*
  * GPIO controller

plat/rpi/rpi4/platform.mk

@@ -11,6 +11,7 @@ PLAT_INCLUDES		:=	-Iplat/rpi/common/include		\
 				-Iplat/rpi/rpi4/include
 
 PLAT_BL_COMMON_SOURCES	:=	drivers/ti/uart/aarch64/16550_console.S	\
+				drivers/arm/pl011/aarch64/pl011_console.S \
 				plat/rpi/common/rpi3_common.c		\
 				${XLAT_TABLES_LIB_SRCS}