[POWERPC] Add bootwrapper support for Motorola PrPMC2800 platform

The Motorola PrPMC280 and PrPMC2800 processor modules sit on an F101 or
PrPMC2800 baseboard, respectively.  There are several variants of each
type of processor module which can have different amounts of memory,
amounts of FLASH, cpu frequencies, and an mv64360 or an mv64362.

The bootwrapper code for that platform reads VPD from an I2C EEPROM
to determine the processor module variant.  From the variant, the
amount of memory, etc. is determined and the device tree is updated
accordingly.  If the variant cannot be determined (e.g., corrupted
VPD or a previously unknown variant), the property values already
in the device tree are used.

Also, the firmware for those platforms does not completely configure
the mv64x60 host bridge so that configuration is done here.

Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 579 insertions, 1 deletions

diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index 12fd57e11fa5..d4f9fef7f9e9 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -45,7 +45,7 @@ src-wlib := string.S crt0.S stdio.c main.c flatdevtree.c flatdevtree_misc.c \
                 gunzip_util.c elf_util.c $(zlib) devtree.c \
                 44x.c ebony.c mv64x60.c mpsc.c mv64x60_i2c.c
 src-plat := of.c cuboot-83xx.c cuboot-85xx.c holly.c \
-                cuboot-ebony.c treeboot-ebony.c
+                cuboot-ebony.c treeboot-ebony.c prpmc2800.c
 src-boot := $(src-wlib) $(src-plat) empty.c
 
 src-boot := $(addprefix $(obj)/, $(src-boot))
@@ -132,6 +132,7 @@ image-$(CONFIG_PPC_CHRP)		+= zImage.chrp
 image-$(CONFIG_PPC_EFIKA)               += zImage.chrp
 image-$(CONFIG_PPC_PMAC)                += zImage.pmac
 image-$(CONFIG_PPC_HOLLY)               += zImage.holly-elf
+image-$(CONFIG_PPC_PRPMC2800)           += zImage.prpmc2800
 image-$(CONFIG_DEFAULT_UIMAGE)          += uImage
 
 ifneq ($(CONFIG_DEVICE_TREE),"")
diff --git a/arch/powerpc/boot/prpmc2800.c b/arch/powerpc/boot/prpmc2800.c
new file mode 100644
index 000000000000..f428bac10d4a
--- /dev/null
+++ b/arch/powerpc/boot/prpmc2800.c
@@ -0,0 +1,577 @@
+/*
+ * Motorola ECC prpmc280/f101 & prpmc2800/f101e platform code.
+ *
+ * Author: Mark A. Greer <mgreer@mvista.com>
+ *
+ * 2007 (c) MontaVista, Software, Inc.  This file is licensed under
+ * the terms of the GNU General Public License version 2.  This program
+ * is licensed "as is" without any warranty of any kind, whether express
+ * or implied.
+ */
+
+#include <stdarg.h>
+#include <stddef.h>
+#include "types.h"
+#include "elf.h"
+#include "page.h"
+#include "string.h"
+#include "stdio.h"
+#include "io.h"
+#include "ops.h"
+#include "gunzip_util.h"
+#include "mv64x60.h"
+
+extern char _end[];
+extern char _vmlinux_start[], _vmlinux_end[];
+extern char _dtb_start[], _dtb_end[];
+
+extern void udelay(long delay);
+
+#define KB      1024U
+#define MB      (KB*KB)
+#define GB      (KB*MB)
+#define MHz     (1000U*1000U)
+#define GHz     (1000U*MHz)
+
+#define BOARD_MODEL     "PrPMC2800"
+#define BOARD_MODEL_MAX 32 /* max strlen(BOARD_MODEL) + 1 */
+
+#define EEPROM2_ADDR    0xa4
+#define EEPROM3_ADDR    0xa8
+
+BSS_STACK(16*KB);
+
+static u8 *bridge_base;
+
+typedef enum {
+        BOARD_MODEL_PRPMC280,
+        BOARD_MODEL_PRPMC2800,
+} prpmc2800_board_model;
+
+typedef enum {
+        BRIDGE_TYPE_MV64360,
+        BRIDGE_TYPE_MV64362,
+} prpmc2800_bridge_type;
+
+struct prpmc2800_board_info {
+        prpmc2800_board_model model;
+        char variant;
+        prpmc2800_bridge_type bridge_type;
+        u8 subsys0;
+        u8 subsys1;
+        u8 vpd4;
+        u8 vpd4_mask;
+        u32 core_speed;
+        u32 mem_size;
+        u32 boot_flash;
+        u32 user_flash;
+};
+
+static struct prpmc2800_board_info prpmc2800_board_info[] = {
+        {
+                .model          = BOARD_MODEL_PRPMC280,
+                .variant        = 'a',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xff,
+                .subsys1        = 0xff,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x0f,
+                .core_speed     = 1*GHz,
+                .mem_size       = 512*MB,
+                .boot_flash     = 1*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC280,
+                .variant        = 'b',
+                .bridge_type    = BRIDGE_TYPE_MV64362,
+                .subsys0        = 0xff,
+                .subsys1        = 0xff,
+                .vpd4           = 0x01,
+                .vpd4_mask      = 0x0f,
+                .core_speed     = 1*GHz,
+                .mem_size       = 512*MB,
+                .boot_flash     = 0,
+                .user_flash     = 0,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC280,
+                .variant        = 'c',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xff,
+                .subsys1        = 0xff,
+                .vpd4           = 0x02,
+                .vpd4_mask      = 0x0f,
+                .core_speed     = 733*MHz,
+                .mem_size       = 512*MB,
+                .boot_flash     = 1*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC280,
+                .variant        = 'd',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xff,
+                .subsys1        = 0xff,
+                .vpd4           = 0x03,
+                .vpd4_mask      = 0x0f,
+                .core_speed     = 1*GHz,
+                .mem_size       = 1*GB,
+                .boot_flash     = 1*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC280,
+                .variant        = 'e',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xff,
+                .subsys1        = 0xff,
+                .vpd4           = 0x04,
+                .vpd4_mask      = 0x0f,
+                .core_speed     = 1*GHz,
+                .mem_size       = 512*MB,
+                .boot_flash     = 1*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC280,
+                .variant        = 'f',
+                .bridge_type    = BRIDGE_TYPE_MV64362,
+                .subsys0        = 0xff,
+                .subsys1        = 0xff,
+                .vpd4           = 0x05,
+                .vpd4_mask      = 0x0f,
+                .core_speed     = 733*MHz,
+                .mem_size       = 128*MB,
+                .boot_flash     = 1*MB,
+                .user_flash     = 0,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC280,
+                .variant        = 'g',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xff,
+                .subsys1        = 0xff,
+                .vpd4           = 0x06,
+                .vpd4_mask      = 0x0f,
+                .core_speed     = 1*GHz,
+                .mem_size       = 256*MB,
+                .boot_flash     = 1*MB,
+                .user_flash     = 0,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC280,
+                .variant        = 'h',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xff,
+                .subsys1        = 0xff,
+                .vpd4           = 0x07,
+                .vpd4_mask      = 0x0f,
+                .core_speed     = 1*GHz,
+                .mem_size       = 1*GB,
+                .boot_flash     = 1*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC2800,
+                .variant        = 'a',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xb2,
+                .subsys1        = 0x8c,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x00,
+                .core_speed     = 1*GHz,
+                .mem_size       = 512*MB,
+                .boot_flash     = 2*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC2800,
+                .variant        = 'b',
+                .bridge_type    = BRIDGE_TYPE_MV64362,
+                .subsys0        = 0xb2,
+                .subsys1        = 0x8d,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x00,
+                .core_speed     = 1*GHz,
+                .mem_size       = 512*MB,
+                .boot_flash     = 0,
+                .user_flash     = 0,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC2800,
+                .variant        = 'c',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xb2,
+                .subsys1        = 0x8e,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x00,
+                .core_speed     = 733*MHz,
+                .mem_size       = 512*MB,
+                .boot_flash     = 2*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC2800,
+                .variant        = 'd',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xb2,
+                .subsys1        = 0x8f,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x00,
+                .core_speed     = 1*GHz,
+                .mem_size       = 1*GB,
+                .boot_flash     = 2*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC2800,
+                .variant        = 'e',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xa2,
+                .subsys1        = 0x8a,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x00,
+                .core_speed     = 1*GHz,
+                .mem_size       = 512*MB,
+                .boot_flash     = 2*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC2800,
+                .variant        = 'f',
+                .bridge_type    = BRIDGE_TYPE_MV64362,
+                .subsys0        = 0xa2,
+                .subsys1        = 0x8b,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x00,
+                .core_speed     = 733*MHz,
+                .mem_size       = 128*MB,
+                .boot_flash     = 2*MB,
+                .user_flash     = 0,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC2800,
+                .variant        = 'g',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xa2,
+                .subsys1        = 0x8c,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x00,
+                .core_speed     = 1*GHz,
+                .mem_size       = 2*GB,
+                .boot_flash     = 2*MB,
+                .user_flash     = 64*MB,
+        },
+        {
+                .model          = BOARD_MODEL_PRPMC2800,
+                .variant        = 'h',
+                .bridge_type    = BRIDGE_TYPE_MV64360,
+                .subsys0        = 0xa2,
+                .subsys1        = 0x8d,
+                .vpd4           = 0x00,
+                .vpd4_mask      = 0x00,
+                .core_speed     = 733*MHz,
+                .mem_size       = 1*GB,
+                .boot_flash     = 2*MB,
+                .user_flash     = 64*MB,
+        },
+};
+
+static struct prpmc2800_board_info *prpmc2800_get_board_info(u8 *vpd)
+{
+        struct prpmc2800_board_info *bip;
+        int i;
+
+        for (i=0,bip=prpmc2800_board_info; i<ARRAY_SIZE(prpmc2800_board_info);
+                        i++,bip++)
+                if ((vpd[0] == bip->subsys0) && (vpd[1] == bip->subsys1)
+                                && ((vpd[4] & bip->vpd4_mask) == bip->vpd4))
+                        return bip;
+
+        return NULL;
+}
+
+/* Get VPD from i2c eeprom 2, then match it to a board info entry */
+static struct prpmc2800_board_info *prpmc2800_get_bip(void)
+{
+        struct prpmc2800_board_info *bip;
+        u8 vpd[5];
+        int rc;
+
+        if (mv64x60_i2c_open())
+                fatal("Error: Can't open i2c device\n\r");
+
+        /* Get VPD from i2c eeprom-2 */
+        memset(vpd, 0, sizeof(vpd));
+        rc = mv64x60_i2c_read(EEPROM2_ADDR, vpd, 0x1fde, 2, sizeof(vpd));
+        if (rc < 0)
+                fatal("Error: Couldn't read eeprom2\n\r");
+        mv64x60_i2c_close();
+
+        /* Get board type & related info */
+        bip = prpmc2800_get_board_info(vpd);
+        if (bip == NULL) {
+                printf("Error: Unsupported board or corrupted VPD:\n\r");
+                printf("  0x%x 0x%x 0x%x 0x%x 0x%x\n\r",
+                                vpd[0], vpd[1], vpd[2], vpd[3], vpd[4]);
+                printf("Using device tree defaults...\n\r");
+        }
+
+        return bip;
+}
+
+static void prpmc2800_bridge_setup(u32 mem_size)
+{
+        u32 i, v[12], enables, acc_bits;
+        u32 pci_base_hi, pci_base_lo, size, buf[2];
+        unsigned long cpu_base;
+        int rc;
+        void *devp;
+        u8 *bridge_pbase, is_coherent;
+        struct mv64x60_cpu2pci_win *tbl;
+
+        bridge_pbase = mv64x60_get_bridge_pbase();
+        is_coherent = mv64x60_is_coherent();
+
+        if (is_coherent)
+                acc_bits = MV64x60_PCI_ACC_CNTL_SNOOP_WB
+                        | MV64x60_PCI_ACC_CNTL_SWAP_NONE
+                        | MV64x60_PCI_ACC_CNTL_MBURST_32_BYTES
+                        | MV64x60_PCI_ACC_CNTL_RDSIZE_32_BYTES;
+        else
+                acc_bits = MV64x60_PCI_ACC_CNTL_SNOOP_NONE
+                        | MV64x60_PCI_ACC_CNTL_SWAP_NONE
+                        | MV64x60_PCI_ACC_CNTL_MBURST_128_BYTES
+                        | MV64x60_PCI_ACC_CNTL_RDSIZE_256_BYTES;
+
+        mv64x60_config_ctlr_windows(bridge_base, bridge_pbase, is_coherent);
+        mv64x60_config_pci_windows(bridge_base, bridge_pbase, 0, 0, mem_size,
+                        acc_bits);
+
+        /* Get the cpu -> pci i/o & mem mappings from the device tree */
+        devp = finddevice("/mv64x60/pci@80000000");
+        if (devp == NULL)
+                fatal("Error: Missing /mv64x60/pci@80000000"
+                                " device tree node\n\r");
+
+        rc = getprop(devp, "ranges", v, sizeof(v));
+        if (rc != sizeof(v))
+                fatal("Error: Can't find /mv64x60/pci@80000000/ranges"
+                                " property\n\r");
+
+        /* Get the cpu -> pci i/o & mem mappings from the device tree */
+        devp = finddevice("/mv64x60");
+        if (devp == NULL)
+                fatal("Error: Missing /mv64x60 device tree node\n\r");
+
+        enables = in_le32((u32 *)(bridge_base + MV64x60_CPU_BAR_ENABLE));
+        enables |= 0x0007fe00; /* Disable all cpu->pci windows */
+        out_le32((u32 *)(bridge_base + MV64x60_CPU_BAR_ENABLE), enables);
+
+        for (i=0; i<12; i+=6) {
+                switch (v[i] & 0xff000000) {
+                case 0x01000000: /* PCI I/O Space */
+                        tbl = mv64x60_cpu2pci_io;
+                        break;
+                case 0x02000000: /* PCI MEM Space */
+                        tbl = mv64x60_cpu2pci_mem;
+                        break;
+                default:
+                        continue;
+                }
+
+                pci_base_hi = v[i+1];
+                pci_base_lo = v[i+2];
+                cpu_base = v[i+3];
+                size = v[i+5];
+
+                buf[0] = cpu_base;
+                buf[1] = size;
+
+                if (!dt_xlate_addr(devp, buf, sizeof(buf), &cpu_base))
+                        fatal("Error: Can't translate PCI address 0x%x\n\r",
+                                        (u32)cpu_base);
+
+                mv64x60_config_cpu2pci_window(bridge_base, 0, pci_base_hi,
+                                pci_base_lo, cpu_base, size, tbl);
+        }
+
+        enables &= ~0x00000600; /* Enable cpu->pci0 i/o, cpu->pci0 mem0 */
+        out_le32((u32 *)(bridge_base + MV64x60_CPU_BAR_ENABLE), enables);
+}
+
+static void prpmc2800_fixups(void)
+{
+        u32 v[2], l, mem_size;
+        int rc;
+        void *devp;
+        char model[BOARD_MODEL_MAX];
+        struct prpmc2800_board_info *bip;
+
+        bip = prpmc2800_get_bip(); /* Get board info based on VPD */
+
+        mem_size = (bip) ? bip->mem_size : mv64x60_get_mem_size(bridge_base);
+        prpmc2800_bridge_setup(mem_size); /* Do necessary bridge setup */
+
+        /* If the VPD doesn't match what we know about, just use the
+         * defaults already in the device tree.
+         */
+        if (!bip)
+                return;
+
+        /* Know the board type so override device tree defaults */
+        /* Set /model appropriately */
+        devp = finddevice("/");
+        if (devp == NULL)
+                fatal("Error: Missing '/' device tree node\n\r");
+        memset(model, 0, BOARD_MODEL_MAX);
+        strncpy(model, BOARD_MODEL, BOARD_MODEL_MAX - 2);
+        l = strlen(model);
+        if (bip->model == BOARD_MODEL_PRPMC280)
+                l--;
+        model[l++] = bip->variant;
+        model[l++] = '\0';
+        setprop(devp, "model", model, l);
+
+        /* Set /cpus/PowerPC,7447/clock-frequency */
+        devp = finddevice("/cpus/PowerPC,7447");
+        if (devp == NULL)
+                fatal("Error: Missing proper /cpus device tree node\n\r");
+        v[0] = bip->core_speed;
+        setprop(devp, "clock-frequency", &v[0], sizeof(v[0]));
+
+        /* Set /memory/reg size */
+        devp = finddevice("/memory");
+        if (devp == NULL)
+                fatal("Error: Missing /memory device tree node\n\r");
+        v[0] = 0;
+        v[1] = bip->mem_size;
+        setprop(devp, "reg", v, sizeof(v));
+
+        /* Update /mv64x60/model, if this is a mv64362 */
+        if (bip->bridge_type == BRIDGE_TYPE_MV64362) {
+                devp = finddevice("/mv64x60");
+                if (devp == NULL)
+                        fatal("Error: Missing /mv64x60 device tree node\n\r");
+                setprop(devp, "model", "mv64362", strlen("mv64362") + 1);
+        }
+
+        /* Set User FLASH size */
+        devp = finddevice("/mv64x60/flash@a0000000");
+        if (devp == NULL)
+                fatal("Error: Missing User FLASH device tree node\n\r");
+        rc = getprop(devp, "reg", v, sizeof(v));
+        if (rc != sizeof(v))
+                fatal("Error: Can't find User FLASH reg property\n\r");
+        v[1] = bip->user_flash;
+        setprop(devp, "reg", v, sizeof(v));
+}
+
+#define MV64x60_MPP_CNTL_0      0xf000
+#define MV64x60_MPP_CNTL_2      0xf008
+#define MV64x60_GPP_IO_CNTL     0xf100
+#define MV64x60_GPP_LEVEL_CNTL  0xf110
+#define MV64x60_GPP_VALUE_SET   0xf118
+
+static void prpmc2800_reset(void)
+{
+        u32 temp;
+
+        udelay(5000000);
+
+        if (bridge_base != 0) {
+                temp = in_le32((u32 *)(bridge_base + MV64x60_MPP_CNTL_0));
+                temp &= 0xFFFF0FFF;
+                out_le32((u32 *)(bridge_base + MV64x60_MPP_CNTL_0), temp);
+
+                temp = in_le32((u32 *)(bridge_base + MV64x60_GPP_LEVEL_CNTL));
+                temp |= 0x00000004;
+                out_le32((u32 *)(bridge_base + MV64x60_GPP_LEVEL_CNTL), temp);
+
+                temp = in_le32((u32 *)(bridge_base + MV64x60_GPP_IO_CNTL));
+                temp |= 0x00000004;
+                out_le32((u32 *)(bridge_base + MV64x60_GPP_IO_CNTL), temp);
+
+                temp = in_le32((u32 *)(bridge_base + MV64x60_MPP_CNTL_2));
+                temp &= 0xFFFF0FFF;
+                out_le32((u32 *)(bridge_base + MV64x60_MPP_CNTL_2), temp);
+
+                temp = in_le32((u32 *)(bridge_base + MV64x60_GPP_LEVEL_CNTL));
+                temp |= 0x00080000;
+                out_le32((u32 *)(bridge_base + MV64x60_GPP_LEVEL_CNTL), temp);
+
+                temp = in_le32((u32 *)(bridge_base + MV64x60_GPP_IO_CNTL));
+                temp |= 0x00080000;
+                out_le32((u32 *)(bridge_base + MV64x60_GPP_IO_CNTL), temp);
+
+                out_le32((u32 *)(bridge_base + MV64x60_GPP_VALUE_SET),
+                                0x00080004);
+        }
+
+        for (;;);
+}
+
+#define HEAP_SIZE       (16*MB)
+static struct gunzip_state gzstate;
+
+void platform_init(unsigned long r3, unsigned long r4, unsigned long r5,
+                   unsigned long r6, unsigned long r7)
+{
+        struct elf_info ei;
+        char *heap_start, *dtb;
+        int dt_size = _dtb_end - _dtb_start;
+        void *vmlinuz_addr = _vmlinux_start;
+        unsigned long vmlinuz_size = _vmlinux_end - _vmlinux_start;
+        char elfheader[256];
+
+        if (dt_size <= 0) /* No fdt */
+                exit();
+
+        /*
+         * Start heap after end of the kernel (after decompressed to
+         * address 0) or the end of the zImage, whichever is higher.
+         * That's so things allocated by simple_alloc won't overwrite
+         * any part of the zImage and the kernel won't overwrite the dtb
+         * when decompressed & relocated.
+         */
+        gunzip_start(&gzstate, vmlinuz_addr, vmlinuz_size);
+        gunzip_exactly(&gzstate, elfheader, sizeof(elfheader));
+
+        if (!parse_elf32(elfheader, &ei))
+                exit();
+
+        heap_start = (char *)(ei.memsize + ei.elfoffset); /* end of kernel*/
+        heap_start = max(heap_start, (char *)_end); /* end of zImage */
+
+        if ((unsigned)simple_alloc_init(heap_start, HEAP_SIZE, 2*KB, 16)
+                        > (128*MB))
+                exit();
+
+        /* Relocate dtb to safe area past end of zImage & kernel */
+        dtb = malloc(dt_size);
+        if (!dtb)
+                exit();
+        memmove(dtb, _dtb_start, dt_size);
+        if (ft_init(dtb, dt_size, 16))
+                exit();
+
+        bridge_base = mv64x60_get_bridge_base();
+
+        platform_ops.fixups = prpmc2800_fixups;
+        platform_ops.exit = prpmc2800_reset;
+
+        if (serial_console_init() < 0)
+                exit();
+}
+
+/* _zimage_start called very early--need to turn off external interrupts */
+asm ("  .globl _zimage_start\n\
+        _zimage_start:\n\
+                mfmsr   10\n\
+                rlwinm  10,10,0,~(1<<15)        /* Clear MSR_EE */\n\
+                sync\n\
+                mtmsr   10\n\
+                isync\n\
+                b _zimage_start_lib\n\
+");