1/* The head-file for the Shark 2 * by Alexander Schulz 3 * 4 * Does the following: 5 * - get the memory layout from firmware. This can only be done as long as the mmu 6 * is still on. 7 * - switch the mmu off, so we have physical addresses 8 * - copy the kernel to 0x08508000. This is done to have a fixed address where the 9 * C-parts (misc.c) are executed. This address must be known at compile-time, 10 * but the load-address of the kernel depends on how much memory is installed. 11 * - Jump to this location. 12 * - Set r8 with 0, r7 with the architecture ID for head.S 13 */ 14 15#include <linux/linkage.h> 16 17#include <asm/assembler.h> 18 19 .section ".start", #alloc, #execinstr 20 21 b __beginning 22 23__ofw_data: .long 0 @ the number of memory blocks 24 .space 128 @ (startaddr,size) ... 25 .space 128 @ bootargs 26 .align 27 28__beginning: mov r4, r0 @ save the entry to the firmware 29 30 mov r0, #0xC0 @ disable irq and fiq 31 mov r1, r0 32 mrs r3, cpsr 33 bic r2, r3, r0 34 eor r2, r2, r1 35 msr cpsr_c, r2 36 37 mov r0, r4 @ get the Memory layout from firmware 38 adr r1, __ofw_data 39 add r2, r1, #4 40 mov lr, pc 41 b SYMBOL_NAME(ofw_init) 42 mov r1, #0 43 44 adr r2, __mmu_off @ calculate physical address 45 sub r2, r2, #0xf0000000 @ openprom maps us at f000 virt, 0e50 phys 46 adr r0, __ofw_data 47 ldr r0, [r0, #4] 48 add r2, r2, r0 49 add r2, r2, #0x00500000 50 51 mrc p15, 0, r3, c1, c0 52 bic r3, r3, #0xC @ Write Buffer and DCache 53 bic r3, r3, #0x1000 @ ICache 54 mcr p15, 0, r3, c1, c0 @ disabled 55 56 mov r0, #0 57 mcr p15, 0, r0, c7, c7 @ flush I,D caches on v4 58 mcr p15, 0, r0, c7, c10, 4 @ drain write buffer on v4 59 mcr p15, 0, r0, c8, c7 @ flush I,D TLBs on v4 60 61 bic r3, r3, #0x1 @ MMU 62 mcr p15, 0, r3, c1, c0 @ disabled 63 64 mov pc, r2 65 66__copy_target: .long 0x08508000 67__copy_end: .long 0x08608000 68 69 .word _start 70 .word __bss_start 71 72 .align 73__temp_stack: .space 128 74 75__mmu_off: 76 adr r0, __ofw_data 77 ldr r0, [r0, #4] 78 orr r0, r0, #0x00600000 79 80 ldr r1, __copy_end 81 ldr r3, __copy_target 82 83/* r0 = 0x0e600000 (current end of kernelcode) 84 * r3 = 0x08508000 (where it should begin) 85 * r1 = 0x08608000 (end of copying area, 1MB) 86 * The kernel is compressed, so 1 MB should be enough. 87 * copy the kernel to the beginning of physical memory 88 * We start from the highest address, so we can copy 89 * from 0x08500000 to 0x08508000 if we have only 8MB 90 */ 91 92 93__Copy: ldr r2, [r0], #-4 94 str r2, [r1], #-4 95 teq r1, r3 96 bne __Copy 97 /* and jump to it */ 98 adr r2, __go_on 99 adr r0, __ofw_data 100 ldr r0, [r0, #4] 101 sub r2, r2, r0 102 sub r2, r2, #0x00500000 103 ldr r0, __copy_target 104 add r2, r2, r0 105 mov pc, r2 106 107__go_on: 108 adr sp, __temp_stack 109 add sp, sp, #128 110 adr r0, __ofw_data 111 mov lr, pc 112 b SYMBOL_NAME(create_params) 113 114 mov r8, #0 115 mov r7, #15 116