#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
.define __exit
__exit:
+ mov r0, sr
ld fp, .returnfp
ld sp, .returnsp
ld lr, .returnlr
--- /dev/null
+/*
+ * 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
+
--- /dev/null
+#
+/*
+ * 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
+
public / ack.git / commitdiff