powerpc/44x: Kexec support for PPC440X chipsets

This patch adds kexec support for PPC440 based chipsets.  This work is based
on the KEXEC patches for FSL BookE.

The FSL BookE patch and the code flow could be found at the link below:

	http://patchwork.ozlabs.org/patch/49359/

Steps:

1) Invalidate all the TLB entries except the one this code is run from
2) Create a tmp mapping for our code in the other address space and jump to it
3) Invalidate the entry we used
4) Create a 1:1 mapping for 0-2GiB in blocks of 256M
5) Jump to the new 1:1 mapping and invalidate the tmp mapping

I have tested this patches on Ebony, Sequoia boards and Virtex on QEMU.

You need kexec-tools commit e8b7939b1e or newer for ppc440x support, 
available at:

 git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git

Signed-off-by: 	Suzuki Poulose <suzuki@in.ibm.com>
Cc:	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>

3 files changed, 173 insertions, 2 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6926b61acfea..0a3d5560c9be 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -345,7 +345,7 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
 
 config KEXEC
         bool "kexec system call (EXPERIMENTAL)"
-        depends on (PPC_BOOK3S || FSL_BOOKE) && EXPERIMENTAL
+        depends on (PPC_BOOK3S || FSL_BOOKE || (44x && !SMP && !47x)) && EXPERIMENTAL
         help
           kexec is a system call that implements the ability to shutdown your
           current kernel, and to start another kernel.  It is like a reboot
diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 8a33698c61bd..f921eb121d39 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -2,7 +2,7 @@
 #define _ASM_POWERPC_KEXEC_H
 #ifdef __KERNEL__
 
-#ifdef CONFIG_FSL_BOOKE
+#if defined(CONFIG_FSL_BOOKE) || defined(CONFIG_44x)
 
 /*
  * On FSL-BookE we setup a 1:1 mapping which covers the first 2GiB of memory
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 998a10028608..f7d760ab5ca1 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -8,6 +8,8 @@
  * kexec bits:
  * Copyright (C) 2002-2003 Eric Biederman  <ebiederm@xmission.com>
  * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz
+ * PPC44x port. Copyright (C) 2011,  IBM Corporation
+ *              Author: Suzuki Poulose <suzuki@in.ibm.com>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -736,6 +738,175 @@ relocate_new_kernel:
         mr      r5, r31
 
         li      r0, 0
+#elif defined(CONFIG_44x)  && !defined(CONFIG_47x)
+
+/*
+ * Code for setting up 1:1 mapping for PPC440x for KEXEC
+ *
+ * We cannot switch off the MMU on PPC44x.
+ * So we:
+ * 1) Invalidate all the mappings except the one we are running from.
+ * 2) Create a tmp mapping for our code in the other address space(TS) and
+ *    jump to it. Invalidate the entry we started in.
+ * 3) Create a 1:1 mapping for 0-2GiB in chunks of 256M in original TS.
+ * 4) Jump to the 1:1 mapping in original TS.
+ * 5) Invalidate the tmp mapping.
+ *
+ * - Based on the kexec support code for FSL BookE
+ * - Doesn't support 47x yet.
+ *
+ */
+        /* Save our parameters */
+        mr      r29, r3
+        mr      r30, r4
+        mr      r31, r5
+
+        /* Load our MSR_IS and TID to MMUCR for TLB search */
+        mfspr   r3,SPRN_PID
+        mfmsr   r4
+        andi.   r4,r4,MSR_IS@l
+        beq     wmmucr
+        oris    r3,r3,PPC44x_MMUCR_STS@h
+wmmucr:
+        mtspr   SPRN_MMUCR,r3
+        sync
+
+        /*
+         * Invalidate all the TLB entries except the current entry
+         * where we are running from
+         */
+        bl      0f                              /* Find our address */
+0:      mflr    r5                              /* Make it accessible */
+        tlbsx   r23,0,r5                        /* Find entry we are in */
+        li      r4,0                            /* Start at TLB entry 0 */
+        li      r3,0                            /* Set PAGEID inval value */
+1:      cmpw    r23,r4                          /* Is this our entry? */
+        beq     skip                            /* If so, skip the inval */
+        tlbwe   r3,r4,PPC44x_TLB_PAGEID         /* If not, inval the entry */
+skip:
+        addi    r4,r4,1                         /* Increment */
+        cmpwi   r4,64                           /* Are we done? */
+        bne     1b                              /* If not, repeat */
+        isync
+
+        /* Create a temp mapping and jump to it */
+        andi.   r6, r23, 1              /* Find the index to use */
+        addi    r24, r6, 1              /* r24 will contain 1 or 2 */
+
+        mfmsr   r9                      /* get the MSR */
+        rlwinm  r5, r9, 27, 31, 31      /* Extract the MSR[IS] */
+        xori    r7, r5, 1               /* Use the other address space */
+
+        /* Read the current mapping entries */
+        tlbre   r3, r23, PPC44x_TLB_PAGEID
+        tlbre   r4, r23, PPC44x_TLB_XLAT
+        tlbre   r5, r23, PPC44x_TLB_ATTRIB
+
+        /* Save our current XLAT entry */
+        mr      r25, r4
+
+        /* Extract the TLB PageSize */
+        li      r10, 1                  /* r10 will hold PageSize */
+        rlwinm  r11, r3, 0, 24, 27      /* bits 24-27 */
+
+        /* XXX: As of now we use 256M, 4K pages */
+        cmpwi   r11, PPC44x_TLB_256M
+        bne     tlb_4k
+        rotlwi  r10, r10, 28            /* r10 = 256M */
+        b       write_out
+tlb_4k:
+        cmpwi   r11, PPC44x_TLB_4K
+        bne     default
+        rotlwi  r10, r10, 12            /* r10 = 4K */
+        b       write_out
+default:
+        rotlwi  r10, r10, 10            /* r10 = 1K */
+
+write_out:
+        /*
+         * Write out the tmp 1:1 mapping for this code in other address space
+         * Fixup  EPN = RPN , TS=other address space
+         */
+        insrwi  r3, r7, 1, 23           /* Bit 23 is TS for PAGEID field */
+
+        /* Write out the tmp mapping entries */
+        tlbwe   r3, r24, PPC44x_TLB_PAGEID
+        tlbwe   r4, r24, PPC44x_TLB_XLAT
+        tlbwe   r5, r24, PPC44x_TLB_ATTRIB
+
+        subi    r11, r10, 1             /* PageOffset Mask = PageSize - 1 */
+        not     r10, r11                /* Mask for PageNum */
+
+        /* Switch to other address space in MSR */
+        insrwi  r9, r7, 1, 26           /* Set MSR[IS] = r7 */
+
+        bl      1f
+1:      mflr    r8
+        addi    r8, r8, (2f-1b)         /* Find the target offset */
+
+        /* Jump to the tmp mapping */
+        mtspr   SPRN_SRR0, r8
+        mtspr   SPRN_SRR1, r9
+        rfi
+
+2:
+        /* Invalidate the entry we were executing from */
+        li      r3, 0
+        tlbwe   r3, r23, PPC44x_TLB_PAGEID
+
+        /* attribute fields. rwx for SUPERVISOR mode */
+        li      r5, 0
+        ori     r5, r5, (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G)
+
+        /* Create 1:1 mapping in 256M pages */
+        xori    r7, r7, 1                       /* Revert back to Original TS */
+
+        li      r8, 0                           /* PageNumber */
+        li      r6, 3                           /* TLB Index, start at 3  */
+
+next_tlb:
+        rotlwi  r3, r8, 28                      /* Create EPN (bits 0-3) */
+        mr      r4, r3                          /* RPN = EPN  */
+        ori     r3, r3, (PPC44x_TLB_VALID | PPC44x_TLB_256M) /* SIZE = 256M, Valid */
+        insrwi  r3, r7, 1, 23                   /* Set TS from r7 */
+
+        tlbwe   r3, r6, PPC44x_TLB_PAGEID       /* PageID field : EPN, V, SIZE */
+        tlbwe   r4, r6, PPC44x_TLB_XLAT         /* Address translation : RPN   */
+        tlbwe   r5, r6, PPC44x_TLB_ATTRIB       /* Attributes */
+
+        addi    r8, r8, 1                       /* Increment PN */
+        addi    r6, r6, 1                       /* Increment TLB Index */
+        cmpwi   r8, 8                           /* Are we done ? */
+        bne     next_tlb
+        isync
+
+        /* Jump to the new mapping 1:1 */
+        li      r9,0
+        insrwi  r9, r7, 1, 26                   /* Set MSR[IS] = r7 */
+
+        bl      1f
+1:      mflr    r8
+        and     r8, r8, r11                     /* Get our offset within page */
+        addi    r8, r8, (2f-1b)
+
+        and     r5, r25, r10                    /* Get our target PageNum */
+        or      r8, r8, r5                      /* Target jump address */
+
+        mtspr   SPRN_SRR0, r8
+        mtspr   SPRN_SRR1, r9
+        rfi
+2:
+        /* Invalidate the tmp entry we used */
+        li      r3, 0
+        tlbwe   r3, r24, PPC44x_TLB_PAGEID
+        sync
+
+        /* Restore the parameters */
+        mr      r3, r29
+        mr      r4, r30
+        mr      r5, r31
+
+        li      r0, 0
 #else
         li      r0, 0