| 1 | ################################################################################# |
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| 2 | # File : reset.s |
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| 3 | # Author : Alain Greiner |
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| 4 | # Date : 15/04/2011 |
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| 5 | ################################################################################# |
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| 6 | # This is a boot code for a generic multi-clusters / multi-processors |
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| 7 | # TSAR architecture (up to 256 clusters / up to 4 processors per cluster). |
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| 8 | # There is one XICU, one TTY, one DMA and one stack segment per cluster. |
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| 9 | # segment base adresses = base + cluster_segment_increment*cluster_id |
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| 10 | # - Each processor initializes the stack pointer ($29) depending on pid. |
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| 11 | # - Only processor 0 initializes the Interrupt vector (TTY, DMA & IOC). |
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| 12 | # - Each processor initialises its private ICU mask register. |
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| 13 | # - Each processor initializes the Status Register (SR) |
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| 14 | # - Each processor initializes the EPC register, and jumps to the main |
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| 15 | # address in kernel mode... |
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| 16 | ################################################################################# |
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| 17 | |
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| 18 | #include <defs.h> |
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| 19 | .section .boot,"ax",@progbits |
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| 20 | |
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| 21 | .extern seg_stack_base |
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| 22 | .extern _boot_loader_entry |
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| 23 | |
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| 24 | .extern dtb_addr |
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| 25 | .extern boot_putc |
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| 26 | .extern boot_getc |
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| 27 | .extern _ioc_read |
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| 28 | |
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| 29 | .globl boot # makes reset an external symbol |
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| 30 | .ent boot |
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| 31 | .align 2 |
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| 32 | .set noreorder |
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| 33 | |
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| 34 | boot: |
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| 35 | b _boot #0xbfc0000 |
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| 36 | nop #0xbfc0004 |
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| 37 | .word BOOT_VERSION #0xbfc0008 |
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| 38 | .word dtb_addr #0xbfc000c |
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| 39 | .word boot_putc #0xbfc0010 |
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| 40 | .word boot_getc #0xbfc0014 |
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| 41 | .word _ioc_read #0xbfc0018 |
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| 42 | |
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| 43 | _boot: |
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| 44 | # Disable interruptions, keep STATUSbev enabled |
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| 45 | |
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| 46 | la $4, (1 << 22) |
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| 47 | mtc0 $4, $12 |
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| 48 | |
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| 49 | # computes proc_id, local_id, cluster_id, and cluster_increment |
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| 50 | |
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| 51 | mfc0 $26, $15, 1 |
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| 52 | andi $10, $26, 0x3FF # $10 <= proc_id (at most 1024 processors) |
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| 53 | la $26, NB_PROCS # $26 <= number of processors per cluster |
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| 54 | divu $10, $26 |
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| 55 | mfhi $11 # $11 <= local_id = proc_id % NB_PROCS |
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| 56 | mflo $12 # $12 <= cluster_id = proc_id / NB_PROCS |
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| 57 | |
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| 58 | mfc0 $26, $15, 1 |
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| 59 | andi $10, $26, 0x3FF # $10 <= proc_id (at most 1024 processors) |
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| 60 | |
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| 61 | la $26, NB_CLUSTERS |
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| 62 | li $13, 0x80000000 |
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| 63 | divu $13, $26 |
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| 64 | mflo $14 |
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| 65 | sll $14, 1 # $14 <= cluster_increment = 4G / NB_CLUSTERS |
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| 66 | mult $14, $12 |
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| 67 | mflo $13 # $13 <= cluster_id * cluster_increment |
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| 68 | |
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| 69 | # Initialization of the count register in the coprocessor 0 |
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| 70 | |
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| 71 | mtc0 $0 , $9 |
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| 72 | |
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| 73 | # in each cluster, the ICU base address depends on the cluster_id |
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| 74 | |
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| 75 | la $20, ICU_BASE |
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| 76 | addu $20, $20, $13 # $20 <= ICU_BASE + cluster_id*cluster_increment |
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| 77 | # we have: |
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| 78 | # $20 xicu base address |
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| 79 | # $12 cluster id |
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| 80 | # $11 local id |
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| 81 | # $10 global id |
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| 82 | # |
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| 83 | # only processor 0 in cluster 0 executes the boot loader |
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| 84 | bne $0, $10, _reset_wait |
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| 85 | nop |
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| 86 | # initializes stack pointer |
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| 87 | |
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| 88 | la $27, seg_stack_base |
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| 89 | li $26, 0x10000 # $26 <= 0x10000 |
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| 90 | addu $29, $27, $26 # $29 <= seg_stack_base + 0x10000 |
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| 91 | |
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| 92 | # Jump to the boot loader routine |
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| 93 | la $26, _boot_loader_entry |
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| 94 | jalr $26 |
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| 95 | nop |
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| 96 | |
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| 97 | # We jump to the main function, which is the entry point in the |
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| 98 | # ELF file. The address is returned by _boot_loader_entry |
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| 99 | # all arguments are 0 |
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| 100 | |
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| 101 | move $4, $0 |
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| 102 | move $5, $0 |
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| 103 | move $6, $0 |
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| 104 | move $7, $0 |
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| 105 | jr $2 |
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| 106 | nop |
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| 107 | |
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| 108 | |
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| 109 | # Wait until the application wakes us. |
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| 110 | # The application wakes up the non-boot CPUs with a IPI with a non-0 |
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| 111 | # value in the mailbox. This non-0 value is the address to jump to. |
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| 112 | _reset_wait: |
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| 113 | # we have: |
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| 114 | # $20 xicu base address |
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| 115 | # $12 cluster id |
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| 116 | # $11 local id |
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| 117 | # $10 global id |
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| 118 | |
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| 119 | sll $13, $11, 2 # $13 = local_id * 4 |
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| 120 | addu $21, $13, $20 # $21 = XICU_WTI_REG(local_id) |
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| 121 | 1: |
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| 122 | lw $2, 0($21) |
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| 123 | beq $0, $2, 1b |
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| 124 | nop |
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| 125 | jr $2 |
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| 126 | |
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| 127 | # exeption entry point |
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| 128 | .org 0x0380 |
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| 129 | _exep: |
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| 130 | mfc0 $4, $12, 0 # first arg is status |
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| 131 | mfc0 $5, $13, 0 # second arg is cause |
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| 132 | mfc0 $6, $14, 0 # third argc is epc |
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| 133 | nop |
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| 134 | j handle_exept |
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| 135 | nop |
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| 136 | |
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| 137 | .end boot |
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| 138 | |
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| 139 | .set reorder |
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