| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * arch/ppc/boot/simple/head.S |
| 3 | * |
| 4 | * Initial board bringup code for many different boards. |
| 5 | * |
| 6 | * Author: Tom Rini |
| 7 | * trini@mvista.com |
| 8 | * Derived from arch/ppc/boot/prep/head.S (Cort Dougan, many others). |
| 9 | * |
| 10 | * 2001-2004 (c) MontaVista, Software, Inc. This file is licensed under |
| 11 | * the terms of the GNU General Public License version 2. This program |
| 12 | * is licensed "as is" without any warranty of any kind, whether express |
| 13 | * or implied. |
| 14 | */ |
| 15 | |
| 16 | #include <linux/config.h> |
| 17 | #include <asm/reg.h> |
| 18 | #include <asm/cache.h> |
| 19 | #include <asm/ppc_asm.h> |
| 20 | |
| 21 | .text |
| 22 | |
| 23 | /* |
| 24 | * Begin at some arbitrary location in RAM or Flash |
| 25 | * Initialize core registers |
| 26 | * Configure memory controller (Not executing from RAM) |
| 27 | * Move the boot code to the link address (8M) |
| 28 | * Setup C stack |
| 29 | * Initialize UART |
| 30 | * Decompress the kernel to 0x0 |
| 31 | * Jump to the kernel entry |
| 32 | * |
| 33 | */ |
| 34 | |
| 35 | .globl start |
| 36 | start: |
| 37 | bl start_ |
| 38 | #ifdef CONFIG_IBM_OPENBIOS |
| 39 | /* The IBM "Tree" bootrom knows that the address of the bootrom |
| 40 | * read only structure is 4 bytes after _start. |
| 41 | */ |
| 42 | .long 0x62726f6d # structure ID - "brom" |
| 43 | .long 0x5f726f00 # - "_ro\0" |
| 44 | .long 1 # structure version |
| 45 | .long bootrom_cmdline # address of *bootrom_cmdline |
| 46 | #endif |
| 47 | |
| 48 | start_: |
| 49 | #ifdef CONFIG_FORCE |
| 50 | /* We have some really bad firmware. We must disable the L1 |
| 51 | * icache/dcache now or the board won't boot. |
| 52 | */ |
| 53 | li r4,0x0000 |
| 54 | isync |
| 55 | mtspr SPRN_HID0,r4 |
| 56 | sync |
| 57 | isync |
| 58 | #endif |
| 59 | |
| 60 | #if defined(CONFIG_MBX) || defined(CONFIG_RPX8260) || defined(CONFIG_PPC_PREP) |
| 61 | mr r29,r3 /* On the MBX860, r3 is the board info pointer. |
| 62 | * On the RPXSUPER, r3 points to the NVRAM |
| 63 | * configuration keys. |
| 64 | * On PReP, r3 is the pointer to the residual data. |
| 65 | */ |
| 66 | #endif |
| 67 | |
| 68 | mflr r3 /* Save our actual starting address. */ |
| 69 | |
| 70 | /* The following functions we call must not modify r3 or r4..... |
| 71 | */ |
| 72 | #ifdef CONFIG_6xx |
| 73 | /* On PReP we must look at the OpenFirmware pointer and sanity |
| 74 | * test it. On other platforms, we disable the MMU right now |
| 75 | * and other bits. |
| 76 | */ |
| 77 | #ifdef CONFIG_PPC_PREP |
| 78 | /* |
| 79 | * Save the OF pointer to r25, but only if the entry point is in a sane |
| 80 | * location; if not we store 0. If there is no entry point, or it is |
| 81 | * invalid, we establish the default MSR value immediately. Otherwise, |
| 82 | * we defer doing that, to allow OF functions to be called, until we |
| 83 | * begin uncompressing the kernel. |
| 84 | */ |
| 85 | lis r8,0x0fff /* r8 = 0x0fffffff */ |
| 86 | ori r8,r8,0xffff |
| 87 | |
| 88 | subc r8,r8,r5 /* r8 = (r5 <= r8) ? ~0 : 0 */ |
| 89 | subfe r8,r8,r8 |
| 90 | nand r8,r8,r8 |
| 91 | |
| 92 | and. r5,r5,r8 /* r5 will be cleared if (r5 > r8) */ |
| 93 | bne+ haveOF |
| 94 | |
| 95 | li r8,MSR_IP|MSR_FP /* Not OF: set MSR immediately */ |
| 96 | mtmsr r8 |
| 97 | isync |
| 98 | haveOF: |
| 99 | mr r25,r5 |
| 100 | #else |
| 101 | bl disable_6xx_mmu |
| 102 | #endif |
| 103 | bl disable_6xx_l1cache |
| 104 | |
| 105 | CLEAR_CACHES |
| 106 | #endif |
| 107 | |
| 108 | #ifdef CONFIG_8xx |
| 109 | mfmsr r8 /* Turn off interrupts */ |
| 110 | li r9,0 |
| 111 | ori r9,r9,MSR_EE |
| 112 | andc r8,r8,r9 |
| 113 | mtmsr r8 |
| 114 | |
| 115 | /* We do this because some boot roms don't initialize the |
| 116 | * processor correctly. Don't do this if you want to debug |
| 117 | * using a BDM device. |
| 118 | */ |
| 119 | li r4,0 /* Zero DER to prevent FRZ */ |
| 120 | mtspr SPRN_DER,r4 |
| 121 | #endif |
| 122 | |
| 123 | #ifdef CONFIG_REDWOOD_4 |
| 124 | /* All of this Redwood 4 stuff will soon disappear when the |
| 125 | * boot rom is straightened out. |
| 126 | */ |
| 127 | mr r29, r3 /* Easier than changing the other code */ |
| 128 | bl HdwInit |
| 129 | mr r3, r29 |
| 130 | #endif |
| 131 | |
| 132 | #if defined(CONFIG_MBX) || defined(CONFIG_RPX8260) || defined(CONFIG_PPC_PREP) |
| 133 | mr r4,r29 /* put the board info pointer where the relocate |
| 134 | * routine will find it |
| 135 | */ |
| 136 | #endif |
| 137 | |
| 138 | /* Get the load address. |
| 139 | */ |
| 140 | subi r3, r3, 4 /* Get the actual IP, not NIP */ |
| 141 | b relocate |
| 142 | |