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Diffstat (limited to 'arch/ppc/kernel/gemini_prom.S')
| -rw-r--r-- | arch/ppc/kernel/gemini_prom.S | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/arch/ppc/kernel/gemini_prom.S b/arch/ppc/kernel/gemini_prom.S new file mode 100644 index 000000000..095f50e8f --- /dev/null +++ b/arch/ppc/kernel/gemini_prom.S @@ -0,0 +1,94 @@ +/* + * arch/ppc/kernel/gemini_prom.S + * + * Not really prom support code (yet), but sort of anti-prom code. The current + * bootloader does a number of things it shouldn't and doesn't do things that it + * should. The stuff in here is mainly a hodge-podge collection of setup code + * to get the board up and running. + * ---Dan + */ + +#include "ppc_asm.tmpl" +#include "ppc_defs.h" +#include <asm/processor.h> +#include <asm/page.h> +#include <asm/gemini.h> + +#define HID0_ABE (1<<3) + +/* + * On 750's the MMU is on when Linux is booted, so we need to clear out the + * bootloader's BAT settings, make sure we're in supervisor state (gotcha!), + * and turn off the MMU. + * + */ + +_GLOBAL(gemini_prom_init) +#ifdef __SMP__ + /* Since the MMU's on, get stuff in rom space that we'll need */ + lis r4,GEMINI_CPUSTAT@h + ori r4,r4,GEMINI_CPUSTAT@l + lbz r5,0(r4) + andi. r5,r5,3 + mr r24,r5 /* cpu # used later on */ +#endif + mfmsr r4 + li r3,MSR_PR /* ensure supervisor! */ + ori r3,r3,MSR_IR|MSR_DR + andc r4,r4,r3 + mtmsr r4 +#if 0 + /* zero out the bats now that the MMU is off */ +prom_no_mmu: + li r3,0 + mtspr IBAT0U,r3 + mtspr IBAT0L,r3 + mtspr IBAT1U,r3 + mtspr IBAT1L,r3 + mtspr IBAT2U,r3 + mtspr IBAT2L,r3 + mtspr IBAT3U,r3 + mtspr IBAT3L,r3 + + mtspr DBAT0U,r3 + mtspr DBAT0L,r3 + mtspr DBAT1U,r3 + mtspr DBAT1L,r3 + mtspr DBAT2U,r3 + mtspr DBAT2L,r3 + mtspr DBAT3U,r3 + mtspr DBAT3L,r3 +#endif + + /* the bootloader (as far as I'm currently aware) doesn't mess with page + tables, but since we're already here, might as well zap these, too */ + li r4,0 + mtspr SDR1,r4 + + li r4,16 + mtctr r4 + li r3,0 + li r4,0 +3: mtsrin r3,r4 + addi r3,r3,1 + bdnz 3b + +#ifdef __SMP__ + /* The 750 book (and Mot/IBM support) says that this will "assist" snooping + when in SMP. Not sure yet whether this should stay or leave... */ + mfspr r4,HID0 + ori r4,r4,HID0_ABE + mtspr HID0,r4 + sync +#endif /* __SMP__ */ + blr + +/* apparently, SMon doesn't pay attention to HID0[SRST]. Disable the MMU and + branch to 0xfff00100 */ +_GLOBAL(_gemini_reboot) + lis r5,GEMINI_BOOT_INIT@h + ori r5,r5,GEMINI_BOOT_INIT@l + li r6,MSR_IP + mtspr SRR0,r5 + mtspr SRR1,r6 + rfi |