blob: 8c5065d565054f1907a07835991378562d5507bb [file] [log] [blame]
* arch/ppc/platforms/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 <linux/config.h>
#include <asm/reg.h>
#include <asm/page.h>
#include <platforms/gemini.h>
#include <asm/ppc_asm.h>
* 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.
/* Since the MMU's on, get stuff in rom space that we'll need */
ori r4,r4,GEMINI_CPUSTAT@l
lbz r5,0(r4)
andi. r5,r5,3
mr r24,r5 /* cpu # used later on */
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 */
li r3,0
mtspr SPRN_IBAT0U,r3
mtspr SPRN_IBAT0L,r3
mtspr SPRN_IBAT1U,r3
mtspr SPRN_IBAT1L,r3
mtspr SPRN_IBAT2U,r3
mtspr SPRN_IBAT2L,r3
mtspr SPRN_IBAT3U,r3
mtspr SPRN_IBAT3L,r3
mtspr SPRN_DBAT0U,r3
mtspr SPRN_DBAT0L,r3
mtspr SPRN_DBAT1U,r3
mtspr SPRN_DBAT1L,r3
mtspr SPRN_DBAT2U,r3
mtspr SPRN_DBAT2L,r3
mtspr SPRN_DBAT3U,r3
mtspr SPRN_DBAT3L,r3
/* 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 SPRN_SDR1,r4
li r4,16
mtctr r4
li r3,0
li r4,0
3: mtsrin r3,r4
addi r3,r3,1
bdnz 3b
/* 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,SPRN_HID0
ori r4,r4,HID0_ABE
mtspr SPRN_HID0,r4
#endif /* CONFIG_SMP */
/* apparently, SMon doesn't pay attention to HID0[SRST]. Disable the MMU and
branch to 0xfff00100 */
ori r5,r5,GEMINI_BOOT_INIT@l
li r6,MSR_IP
mtspr SPRN_SRR0,r5
mtspr SPRN_SRR1,r6