Build binaries that will run bare metal. Add enough syscall library to init the uart and write text.

--HG--
branch : dtrg-videocore
rename : plat/rpi/libsys/libsys.h => plat/rpi/libsys/libsysasm.h
rename : plat/rpi/libsys/_sys_rawread.s => plat/rpi/libsys/phys_to_user.s
rename : plat/rpi/libsys/_sys_rawread.s => plat/rpi/libsys/uart.s
rename : plat/rpi/libsys/_sys_rawread.s => plat/rpi/libsys/user_to_phys.s

plat/rpi/boot.s

@@ -19,14 +19,17 @@
 #define STACKSIZE 16*1024
 
 ! MAIN ENTRY POINT
-!
-! When running as a kernel, our parameters are passed in in r0-r5, so
-! the startup sequence mustn't disturb these.
 
 begtext:
+	! This empty space is required by the boot loader.
+
+	b start
+	.space 508 ! 512 minus space needed for branch instruction
+
 	! Wipe the bss. This must happen absolutely first, because we need
 	! to store the old system registers into it.
-	
+
+start:
 	lea r6, begbss
 	lea r7, endbss
 	mov r8, #0
@@ -79,6 +82,7 @@ _1:
 
 .define __exit
 __exit:
+	mov r0, sr
 	ld fp, .returnfp
 	ld sp, .returnsp
 	ld lr, .returnlr

plat/rpi/build.mk

@@ -13,10 +13,15 @@ D := plat/rpi/
 
 platform-headers := \
 	unistd.h \
+	pi.h \
 	ack/config.h
 
 platform-libsys := \
 	_hol0.s \
+	phys_to_user.s \
+	user_to_phys.s \
+	uart.s \
+	write.c \
 
 ifeq (x,y)
 	errno.s \
@@ -26,7 +31,6 @@ ifeq (x,y)
 	creat.c \
 	close.c \
 	read.c \
-	write.c \
 	brk.c \
 	getpid.c \
 	kill.c \

plat/rpi/include/pi.h

@@ -0,0 +1,21 @@
+/*
+ * Raspberry Pi support library for the ACK
+ * © 2013 David Given
+ * This file is redistributable under the terms of the 3-clause BSD license.
+ * See the file 'Copying' in the root of the distribution for the full text.
+ */
+
+#ifndef PI_H
+#define PI_H
+
+/* Initialise the mini UART (only do this if running on bare metal! */
+extern void init_uart(void);
+
+/* Converts a pointer from a physical address to a user address. */
+extern void* phys_to_user(void* ptr);
+
+/* Converts a pointer from a user address to a physical address. */
+extern void* user_to_phys(void* ptr);
+
+#endif
+

plat/rpi/libsys/libsysasm.h

@@ -0,0 +1,20 @@
+/*
+ * Raspberry Pi support library for the ACK
+ * © 2013 David Given
+ * This file is redistributable under the terms of the 3-clause BSD license.
+ * See the file 'Copying' in the root of the distribution for the full text.
+ */
+
+#ifndef LIBSYSASM_H
+#define LIBSYSASM_H
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+#define gp r15
+
+#endif

plat/rpi/libsys/phys_to_user.s

@@ -0,0 +1,20 @@
+#
+/*
+ * Raspberry Pi support library for the ACK
+ * © 2013 David Given
+ * This file is redistributable under the terms of the 3-clause BSD license.
+ * See the file 'Copying' in the root of the distribution for the full text.
+ */
+
+#include "libsysasm.h"
+
+.sect .text
+
+! Transforms a physical address into a user address.
+
+.define _phys_to_user
+_phys_to_user:
+	ld r0, 0 (sp)
+	sub r0, gp
+	b lr
+

plat/rpi/libsys/uart.s

@@ -0,0 +1,135 @@
+#
+/*
+ * Raspberry Pi support library for the ACK
+ * © 2013 David Given
+ * This file is redistributable under the terms of the 3-clause BSD license.
+ * See the file 'Copying' in the root of the distribution for the full text.
+ */
+
+#include "libsysasm.h"
+
+.sect .text
+
+! Because of the low system clock rate, this baud rate might be inaccurate
+! So be careful with your serial/terminal, some adjustment may be necessary.
+TARGET_BAUD_RATE = 115200
+
+! System clock is running directly off the 19.2MHz crystal at initial reset
+SYSTEM_CLOCK = 19200000
+
+GPFSEL1 = 0x7e200004
+GPSET0 = 0x7e20001C
+GPCLR0 = 0x7e200028
+GPPUD = 0x7e200094
+GPPUDCLK0 = 0x7e200098
+
+AUX_ENABLES = 0x7e215004
+AUX_MU_IO_REG = 0x7e215040
+AUX_MU_IER_REG = 0x7e215044
+AUX_MU_IIR_REG = 0x7e215048
+AUX_MU_LCR_REG = 0x7e21504C
+AUX_MU_MCR_REG = 0x7e215050
+AUX_MU_LSR_REG = 0x7e215054
+AUX_MU_MSR_REG = 0x7e215058
+AUX_MU_SCRATCH = 0x7e21505C
+AUX_MU_CNTL_REG = 0x7e215060
+AUX_MU_STAT_REG = 0x7e215064
+AUX_MU_BAUD_REG = 0x7e215068
+
+! Sets up the mini UART for use as a console.
+
+.define _init_uart
+_init_uart:
+	! Configure TX and RX GPIO pins for Mini Uart function.
+	mov	r1, #GPFSEL1
+	ld	r0, (r1)
+	and	r0, #~[7<<12]
+	or	r0, #2<<12
+	and	r0, #~[7<<15]
+	or	r0, #2<<15
+	st	r0, (r1)
+
+	mov	r1, #GPPUD
+	mov	r0, #0
+	st	r0, (r1)
+
+delay1:
+	add	r0, #1
+	cmp	r0, #150
+	b.ne delay1
+
+	mov	r1, #GPPUDCLK0
+	mov	r0, #[1<<14]|[1<<15]
+	st	r0, (r1)
+
+	mov	r0, #0
+delay2:
+	add	r0, #1
+	cmp	r0, #150
+	b.ne delay2
+
+	mov	r1, #GPPUDCLK0
+	mov	r0, #0
+	st	r0, (r1)
+
+	! Set up serial port
+	mov	r1, #AUX_ENABLES
+	mov	r0, #1
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_IER_REG
+	mov	r0, #0
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_CNTL_REG
+	mov	r0, #0
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_LCR_REG
+	mov	r0, #3
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_MCR_REG
+	mov	r0, #0
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_IER_REG
+	mov	r0, #0
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_IIR_REG
+	mov	r0, #0xC6
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_BAUD_REG
+	mov	r0, #[[SYSTEM_CLOCK/[TARGET_BAUD_RATE*8]]-1]
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_LCR_REG
+	mov	r0, #3
+	st	r0, (r1)
+
+	mov	r1, #AUX_MU_CNTL_REG
+	mov	r0, #3
+	st	r0, (r1)
+
+	b lr
+
+! Send a single byte.
+
+.define __sys_rawwrite
+__sys_rawwrite:
+	ld r0, (sp)
+	mov r1, #AUX_MU_LSR_REG
+	! loop until space available in Tx buffer
+sendwait:
+	ld	r2, (r1)
+	and	r2, #0x20
+	cmp	r2, #0x20
+	b.ne sendwait
+
+	mov	r1, #AUX_MU_IO_REG
+	stb	r0, (r1)
+
+	b lr
+

plat/rpi/libsys/user_to_phys.s

@@ -0,0 +1,20 @@
+#
+/*
+ * Raspberry Pi support library for the ACK
+ * © 2013 David Given
+ * This file is redistributable under the terms of the 3-clause BSD license.
+ * See the file 'Copying' in the root of the distribution for the full text.
+ */
+
+#include "libsysasm.h"
+
+.sect .text
+
+! Transforms a user address into a physical address.
+
+.define _user_to_phys
+_user_to_phys:
+	ld r0, 0 (sp)
+	add r0, gp
+	b lr
+