/* $NetBSD: ofw_subr.S,v 1.20 2021/02/28 19:01:11 thorpej Exp $ */

/* $NetBSD: ofw_subr.S,v 1.20 2021/02/28 19:01:11 thorpej Exp $ */

/*
* Copyright (C) 1995, 1996 Wolfgang Solfrank.
* Copyright (C) 1995, 1996 TooLs GmbH.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by TooLs GmbH.
* 4. The name of TooLs GmbH may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#ifdef _KERNEL_OPT
#include "opt_ppcarch.h"
#endif

/* Stack used to call into OpenFirmware. */
.lcomm firmstk,NBPG,16

/* Buffer used to pass data to/from OpenFirmware. */
.lcomm OF_buffer,NBPG + 36,4

/* The OpenFirmware entry point, provided by OpenFirmware. */
.lcomm ofentry,4,4

/* Entry trampoline used by openfirmware(). */
.lcomm oftramp,4,4

/* Client SR save area */
.lcomm clsrsave,64,4

/* MSR used in OpenFirmware */
.globl ofwmsr
.comm ofwmsr,4,4

#ifdef FIRMWORKSBUGS
.lcomm ofwreal_incharge,4,4
#endif

/*
* Called by start to save the initial OFW state so we can restore it
* when call back to OFW.
*
* We expect the registers to be as for the entry point into the kernel:
*
* %r1 Stack provided by OpenFirmware / boot loader
* %r5 OpenFirmware client entry point
*
* (others -- don't care)
*/
ENTRY_NOPROFILE(ofwinit)
/* Save return address, Push a stack frame. */
mflr %r0
stw %r0,4(%r1)
stwu %r1,-16(%r1)

#ifdef FIRMWORKSBUGS
mfmsr %r0
andi. %r0,%r0,PSL_IR|PSL_DR
beq 1f

li %r8,1
lis %r9,ofwreal_incharge@ha
stw %r8,ofwreal_incharge@l(%r9)

bl _C_LABEL(ofwr_init)
1:
#endif

lis %r8,ofentry@ha
stw %r5,ofentry@l(%r8) /* save client interface handler */

/*
* Call directly into OpenFirmware until we're ready to use
* the trampoline.
*/
lis %r8,oftramp@ha
stw %r5,oftramp@l(%r8)

/* Save the MSR that OpenFirmware is using. */
mfmsr %r0
lis %r9,ofwmsr@ha
stw %r0,ofwmsr@l(%r9)

lis %r8,OF_buffer@ha
addi %r8,%r8,OF_buffer@l
lis %r9,_C_LABEL(OF_buf)@ha
stw %r8,_C_LABEL(OF_buf)@l(%r9)

/*
* Call into C code to perform additional early initialization.
*/
lis %r8,_C_LABEL(ofw_bootstrap)@ha
addi %r8,%r8,_C_LABEL(ofw_bootstrap)@l
mtctr %r8
bctrl

/*
* Jump off the trampoline for all subsequent calls
* into OpenFirmware.
*/
lis %r5,_C_LABEL(openfirmware_trampoline)@ha
addi %r5,%r5,_C_LABEL(openfirmware_trampoline)@l
lis %r8,oftramp@ha
stw %r5,oftramp@l(%r8)

/* Retrieve LR, pop stack frame. */
addi %r1,%r1,16
lwz %r0,4(%r1)
mtlr %r0

blr

/*
* OpenFirmware trampoline. We are already on the OpenFirmware stack.
*/
ENTRY_NOPROFILE(openfirmware_trampoline)
mflr %r0
stw %r0,4(%r1) /* save return address */

/*
* Push stack frame and save area:
*
* [SP+8 save area]
* [SP+4 slot for saved LR in callee]
* [SP+0 saved SP]
*/
stwu %r1,-48(%r1)

#ifdef FIRMWORKSBUGS
lis %r4,ofwreal_incharge@ha
lwz %r4,ofwreal_incharge@l(%r4)
cmpwi %r4,1
bne 1f
blrl
b 4f
1:
#endif
mfmsr %r4 /* save msr */
stw %r4,8(%r1)

li %r0,0 /* disable MMU */
mtmsr %r0
isync

#if defined (PPC_OEA) || defined (PPC_OEA64_BRIDGE)
/* clear BAT translations */
mtdbatu 2,%r0
mtdbatu 3,%r0
mtibatu 2,%r0
mtibatu 3,%r0
#endif /* PPC_OEA */

lis %r4,clsrsave@ha /* save current SRs */
addi %r4,%r4,clsrsave@l
li %r5,0
1: mfsrin %r0,%r5
stw %r0,0(%r4)
addi %r4,%r4,4
addis %r5,%r5,0x10000000@h
cmpwi %r5,0
bne 1b

lis %r4,_C_LABEL(ofw_pmap)@ha /* load OFW SR */
addi %r4,%r4,_C_LABEL(ofw_pmap)@l
lwz %r0,PM_KERNELSR(%r4)
cmpwi %r0,0 /* pm_sr[KERNEL_SR] == 0? */
beq 2f /* then skip (not initialized yet) */
li %r5,0
1: lwz %r0,0(%r4)
mtsrin %r0,%r5
addi %r4,%r4,4
addis %r5,%r5,0x10000000@h
cmpwi %r5,0
bne 1b
2:
/* curcpu()->ci_battable = &ofw_battable */
GET_CPUINFO(%r4)
lis %r5,_C_LABEL(ofw_battable)@ha
addi %r5,%r5,_C_LABEL(ofw_battable)@l
stw %r5,CI_BATTABLE(%r4)

lis %r4,ofentry@ha /* get firmware entry point */
lwz %r4,ofentry@l(%r4)
mtlr %r4

lis %r4,ofwmsr@ha /* load Open Firmware MSR */
lwz %r5,ofwmsr@l(%r4)
mtmsr %r5
isync

blrl /* call Open Firmware */

li %r0,0 /* ensure disable MMU is disabled */
mtmsr %r0
isync

/* curcpu()->ci_battable = &battable */
GET_CPUINFO(%r4)
lis %r5,_C_LABEL(battable)@ha
addi %r5,%r5,_C_LABEL(battable)@l
stw %r5,CI_BATTABLE(%r4)

lis %r4,clsrsave@ha /* restore saved SRs */
addi %r4,%r4,clsrsave@l
li %r5,0
1: lwz %r0,0(%r4)
mtsrin %r0,%r5
addi %r4,%r4,4
addis %r5,%r5,0x10000000@h
cmpwi %r5,0
bne 1b

lwz %r4,8(%r1) /* restore msr */
mtmsr %r4
isync
4:
addi %r1,%r1,48 /* pop stack frame and save area */
lwz %r0,4(%r1) /* return address */
mtlr %r0
blr

/*
* Call into OpenFirmware.
*/
ENTRY_NOPROFILE(openfirmware)
mflr %r0
stw %r0,4(%r1) /* save return address */

/* Switch to OpenFirmware stack. */
lis %r7,firmstk+NBPG-16@ha
addi %r7,%r7,firmstk+NBPG-16@l
stw %r1,0(%r7) /* stash away prev stack pointer */
mr %r1,%r7

lis %r4,oftramp@ha
lwz %r4,oftramp@l(%r4)

mtctr %r4
bctrl

lwz %r1,0(%r1) /* restore previous stack pointer */
lwz %r0,4(%r1) /* return address */
mtlr %r0
blr