[PATCH] ppc64: firmware workaround

[linux-2.6] / arch / ppc64 / kernel / prom_init.c

/*
 * 
 *
 * Procedures for interfacing to Open Firmware.
 *
 * Paul Mackerras       August 1996.
 * Copyright (C) 1996 Paul Mackerras.
 * 
 *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
 *    {engebret|bergner}@us.ibm.com 
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#undef DEBUG_PROM

#include <stdarg.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/version.h>
#include <linux/threads.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/pci.h>
#include <linux/proc_fs.h>
#include <linux/stringify.h>
#include <linux/delay.h>
#include <linux/initrd.h>
#include <linux/bitops.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/abs_addr.h>
#include <asm/page.h>
#include <asm/processor.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/pci.h>
#include <asm/iommu.h>
#include <asm/bootinfo.h>
#include <asm/ppcdebug.h>
#include <asm/btext.h>
#include <asm/sections.h>
#include <asm/machdep.h>

#ifdef CONFIG_LOGO_LINUX_CLUT224
#include <linux/linux_logo.h>
extern const struct linux_logo logo_linux_clut224;
#endif

/*
 * Properties whose value is longer than this get excluded from our
 * copy of the device tree. This value does need to be big enough to
 * ensure that we don't lose things like the interrupt-map property
 * on a PCI-PCI bridge.
 */
#define MAX_PROPERTY_LENGTH     (1UL * 1024 * 1024)

/*
 * Eventually bump that one up
 */
#define DEVTREE_CHUNK_SIZE      0x100000

/*
 * This is the size of the local memory reserve map that gets copied
 * into the boot params passed to the kernel. That size is totally
 * flexible as the kernel just reads the list until it encounters an
 * entry with size 0, so it can be changed without breaking binary
 * compatibility
 */
#define MEM_RESERVE_MAP_SIZE    8

/*
 * prom_init() is called very early on, before the kernel text
 * and data have been mapped to KERNELBASE.  At this point the code
 * is running at whatever address it has been loaded at, so
 * references to extern and static variables must be relocated
 * explicitly.  The procedure reloc_offset() returns the address
 * we're currently running at minus the address we were linked at.
 * (Note that strings count as static variables.)
 *
 * Because OF may have mapped I/O devices into the area starting at
 * KERNELBASE, particularly on CHRP machines, we can't safely call
 * OF once the kernel has been mapped to KERNELBASE.  Therefore all
 * OF calls should be done within prom_init(), and prom_init()
 * and all routines called within it must be careful to relocate
 * references as necessary.
 *
 * Note that the bss is cleared *after* prom_init runs, so we have
 * to make sure that any static or extern variables it accesses
 * are put in the data segment.
 */


#define PROM_BUG() do {                                         \
        prom_printf("kernel BUG at %s line 0x%x!\n",            \
                    RELOC(__FILE__), __LINE__);                 \
        __asm__ __volatile__(".long " BUG_ILLEGAL_INSTR);       \
} while (0)

#ifdef DEBUG_PROM
#define prom_debug(x...)        prom_printf(x)
#else
#define prom_debug(x...)
#endif


typedef u32 prom_arg_t;

struct prom_args {
        u32 service;
        u32 nargs;
        u32 nret;
        prom_arg_t args[10];
        prom_arg_t *rets;     /* Pointer to return values in args[16]. */
};

struct prom_t {
        unsigned long entry;
        ihandle root;
        ihandle chosen;
        int cpu;
        ihandle stdout;
        ihandle disp_node;
        struct prom_args args;
        unsigned long version;
        unsigned long root_size_cells;
        unsigned long root_addr_cells;
};

struct pci_reg_property {
        struct pci_address addr;
        u32 size_hi;
        u32 size_lo;
};

struct mem_map_entry {
        u64     base;
        u64     size;
};

typedef u32 cell_t;

extern void __start(unsigned long r3, unsigned long r4, unsigned long r5);

extern void enter_prom(struct prom_args *args, unsigned long entry);
extern void copy_and_flush(unsigned long dest, unsigned long src,
                           unsigned long size, unsigned long offset);

extern unsigned long klimit;

/* prom structure */
static struct prom_t __initdata prom;

#define PROM_SCRATCH_SIZE 256

static char __initdata of_stdout_device[256];
static char __initdata prom_scratch[PROM_SCRATCH_SIZE];

static unsigned long __initdata dt_header_start;
static unsigned long __initdata dt_struct_start, dt_struct_end;
static unsigned long __initdata dt_string_start, dt_string_end;

static unsigned long __initdata prom_initrd_start, prom_initrd_end;

static int __initdata iommu_force_on;
static int __initdata ppc64_iommu_off;
static int __initdata of_platform;

static char __initdata prom_cmd_line[COMMAND_LINE_SIZE];

static unsigned long __initdata prom_memory_limit;
static unsigned long __initdata prom_tce_alloc_start;
static unsigned long __initdata prom_tce_alloc_end;

static unsigned long __initdata alloc_top;
static unsigned long __initdata alloc_top_high;
static unsigned long __initdata alloc_bottom;
static unsigned long __initdata rmo_top;
static unsigned long __initdata ram_top;

static struct mem_map_entry __initdata mem_reserve_map[MEM_RESERVE_MAP_SIZE];
static int __initdata mem_reserve_cnt;

static cell_t __initdata regbuf[1024];


#define MAX_CPU_THREADS 2

/* TO GO */
#ifdef CONFIG_HMT
struct {
        unsigned int pir;
        unsigned int threadid;
} hmt_thread_data[NR_CPUS];
#endif /* CONFIG_HMT */

/*
 * This are used in calls to call_prom.  The 4th and following
 * arguments to call_prom should be 32-bit values.  64 bit values
 * are truncated to 32 bits (and fortunately don't get interpreted
 * as two arguments).
 */
#define ADDR(x)         (u32) ((unsigned long)(x) - offset)

/* This is the one and *ONLY* place where we actually call open
 * firmware from, since we need to make sure we're running in 32b
 * mode when we do.  We switch back to 64b mode upon return.
 */

#define PROM_ERROR      (-1)

static int __init call_prom(const char *service, int nargs, int nret, ...)
{
        int i;
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        va_list list;

        _prom->args.service = ADDR(service);
        _prom->args.nargs = nargs;
        _prom->args.nret = nret;
        _prom->args.rets = (prom_arg_t *)&(_prom->args.args[nargs]);

        va_start(list, nret);
        for (i=0; i < nargs; i++)
                _prom->args.args[i] = va_arg(list, prom_arg_t);
        va_end(list);

        for (i=0; i < nret ;i++)
                _prom->args.rets[i] = 0;

        enter_prom(&_prom->args, _prom->entry);

        return (nret > 0) ? _prom->args.rets[0] : 0;
}


static unsigned int __init prom_claim(unsigned long virt, unsigned long size,
                                unsigned long align)
{
        return (unsigned int)call_prom("claim", 3, 1,
                                       (prom_arg_t)virt, (prom_arg_t)size,
                                       (prom_arg_t)align);
}

static void __init prom_print(const char *msg)
{
        const char *p, *q;
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);

        if (_prom->stdout == 0)
                return;

        for (p = msg; *p != 0; p = q) {
                for (q = p; *q != 0 && *q != '\n'; ++q)
                        ;
                if (q > p)
                        call_prom("write", 3, 1, _prom->stdout, p, q - p);
                if (*q == 0)
                        break;
                ++q;
                call_prom("write", 3, 1, _prom->stdout, ADDR("\r\n"), 2);
        }
}


static void __init prom_print_hex(unsigned long val)
{
        unsigned long offset = reloc_offset();
        int i, nibbles = sizeof(val)*2;
        char buf[sizeof(val)*2+1];
        struct prom_t *_prom = PTRRELOC(&prom);

        for (i = nibbles-1;  i >= 0;  i--) {
                buf[i] = (val & 0xf) + '0';
                if (buf[i] > '9')
                        buf[i] += ('a'-'0'-10);
                val >>= 4;
        }
        buf[nibbles] = '\0';
        call_prom("write", 3, 1, _prom->stdout, buf, nibbles);
}


static void __init prom_printf(const char *format, ...)
{
        unsigned long offset = reloc_offset();
        const char *p, *q, *s;
        va_list args;
        unsigned long v;
        struct prom_t *_prom = PTRRELOC(&prom);

        va_start(args, format);
        for (p = PTRRELOC(format); *p != 0; p = q) {
                for (q = p; *q != 0 && *q != '\n' && *q != '%'; ++q)
                        ;
                if (q > p)
                        call_prom("write", 3, 1, _prom->stdout, p, q - p);
                if (*q == 0)
                        break;
                if (*q == '\n') {
                        ++q;
                        call_prom("write", 3, 1, _prom->stdout,
                                  ADDR("\r\n"), 2);
                        continue;
                }
                ++q;
                if (*q == 0)
                        break;
                switch (*q) {
                case 's':
                        ++q;
                        s = va_arg(args, const char *);
                        prom_print(s);
                        break;
                case 'x':
                        ++q;
                        v = va_arg(args, unsigned long);
                        prom_print_hex(v);
                        break;
                }
        }
}


static void __init __attribute__((noreturn)) prom_panic(const char *reason)
{
        unsigned long offset = reloc_offset();

        prom_print(PTRRELOC(reason));
        /* ToDo: should put up an SRC here */
        call_prom("exit", 0, 0);

        for (;;)                        /* should never get here */
                ;
}


static int __init prom_next_node(phandle *nodep)
{
        phandle node;

        if ((node = *nodep) != 0
            && (*nodep = call_prom("child", 1, 1, node)) != 0)
                return 1;
        if ((*nodep = call_prom("peer", 1, 1, node)) != 0)
                return 1;
        for (;;) {
                if ((node = call_prom("parent", 1, 1, node)) == 0)
                        return 0;
                if ((*nodep = call_prom("peer", 1, 1, node)) != 0)
                        return 1;
        }
}

static int __init prom_getprop(phandle node, const char *pname,
                               void *value, size_t valuelen)
{
        unsigned long offset = reloc_offset();

        return call_prom("getprop", 4, 1, node, ADDR(pname),
                         (u32)(unsigned long) value, (u32) valuelen);
}

static int __init prom_getproplen(phandle node, const char *pname)
{
        unsigned long offset = reloc_offset();

        return call_prom("getproplen", 2, 1, node, ADDR(pname));
}

static int __init prom_setprop(phandle node, const char *pname,
                               void *value, size_t valuelen)
{
        unsigned long offset = reloc_offset();

        return call_prom("setprop", 4, 1, node, ADDR(pname),
                         (u32)(unsigned long) value, (u32) valuelen);
}

/* We can't use the standard versions because of RELOC headaches. */
#define isxdigit(c)     (('0' <= (c) && (c) <= '9') \
                         || ('a' <= (c) && (c) <= 'f') \
                         || ('A' <= (c) && (c) <= 'F'))

#define isdigit(c)      ('0' <= (c) && (c) <= '9')
#define islower(c)      ('a' <= (c) && (c) <= 'z')
#define toupper(c)      (islower(c) ? ((c) - 'a' + 'A') : (c))

unsigned long prom_strtoul(const char *cp, const char **endp)
{
        unsigned long result = 0, base = 10, value;

        if (*cp == '0') {
                base = 8;
                cp++;
                if (toupper(*cp) == 'X') {
                        cp++;
                        base = 16;
                }
        }

        while (isxdigit(*cp) &&
               (value = isdigit(*cp) ? *cp - '0' : toupper(*cp) - 'A' + 10) < base) {
                result = result * base + value;
                cp++;
        }

        if (endp)
                *endp = cp;

        return result;
}

unsigned long prom_memparse(const char *ptr, const char **retptr)
{
        unsigned long ret = prom_strtoul(ptr, retptr);
        int shift = 0;

        /*
         * We can't use a switch here because GCC *may* generate a
         * jump table which won't work, because we're not running at
         * the address we're linked at.
         */
        if ('G' == **retptr || 'g' == **retptr)
                shift = 30;

        if ('M' == **retptr || 'm' == **retptr)
                shift = 20;

        if ('K' == **retptr || 'k' == **retptr)
                shift = 10;

        if (shift) {
                ret <<= shift;
                (*retptr)++;
        }

        return ret;
}

/*
 * Early parsing of the command line passed to the kernel, used for
 * "mem=x" and the options that affect the iommu
 */
static void __init early_cmdline_parse(void)
{
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        char *opt, *p;
        int l = 0;

        RELOC(prom_cmd_line[0]) = 0;
        p = RELOC(prom_cmd_line);
        if ((long)_prom->chosen > 0)
                l = prom_getprop(_prom->chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
#ifdef CONFIG_CMDLINE
        if (l == 0) /* dbl check */
                strlcpy(RELOC(prom_cmd_line),
                        RELOC(CONFIG_CMDLINE), sizeof(prom_cmd_line));
#endif /* CONFIG_CMDLINE */
        prom_printf("command line: %s\n", RELOC(prom_cmd_line));

        opt = strstr(RELOC(prom_cmd_line), RELOC("iommu="));
        if (opt) {
                prom_printf("iommu opt is: %s\n", opt);
                opt += 6;
                while (*opt && *opt == ' ')
                        opt++;
                if (!strncmp(opt, RELOC("off"), 3))
                        RELOC(ppc64_iommu_off) = 1;
                else if (!strncmp(opt, RELOC("force"), 5))
                        RELOC(iommu_force_on) = 1;
        }

        opt = strstr(RELOC(prom_cmd_line), RELOC("mem="));
        if (opt) {
                opt += 4;
                RELOC(prom_memory_limit) = prom_memparse(opt, (const char **)&opt);
                /* Align to 16 MB == size of large page */
                RELOC(prom_memory_limit) = ALIGN(RELOC(prom_memory_limit), 0x1000000);
        }
}

/*
 * To tell the firmware what our capabilities are, we have to pass
 * it a fake 32-bit ELF header containing a couple of PT_NOTE sections
 * that contain structures that contain the actual values.
 */
static struct fake_elf {
        Elf32_Ehdr      elfhdr;
        Elf32_Phdr      phdr[2];
        struct chrpnote {
                u32     namesz;
                u32     descsz;
                u32     type;
                char    name[8];        /* "PowerPC" */
                struct chrpdesc {
                        u32     real_mode;
                        u32     real_base;
                        u32     real_size;
                        u32     virt_base;
                        u32     virt_size;
                        u32     load_base;
                } chrpdesc;
        } chrpnote;
        struct rpanote {
                u32     namesz;
                u32     descsz;
                u32     type;
                char    name[24];       /* "IBM,RPA-Client-Config" */
                struct rpadesc {
                        u32     lpar_affinity;
                        u32     min_rmo_size;
                        u32     min_rmo_percent;
                        u32     max_pft_size;
                        u32     splpar;
                        u32     min_load;
                        u32     new_mem_def;
                        u32     ignore_me;
                } rpadesc;
        } rpanote;
} fake_elf = {
        .elfhdr = {
                .e_ident = { 0x7f, 'E', 'L', 'F',
                             ELFCLASS32, ELFDATA2MSB, EV_CURRENT },
                .e_type = ET_EXEC,      /* yeah right */
                .e_machine = EM_PPC,
                .e_version = EV_CURRENT,
                .e_phoff = offsetof(struct fake_elf, phdr),
                .e_phentsize = sizeof(Elf32_Phdr),
                .e_phnum = 2
        },
        .phdr = {
                [0] = {
                        .p_type = PT_NOTE,
                        .p_offset = offsetof(struct fake_elf, chrpnote),
                        .p_filesz = sizeof(struct chrpnote)
                }, [1] = {
                        .p_type = PT_NOTE,
                        .p_offset = offsetof(struct fake_elf, rpanote),
                        .p_filesz = sizeof(struct rpanote)
                }
        },
        .chrpnote = {
                .namesz = sizeof("PowerPC"),
                .descsz = sizeof(struct chrpdesc),
                .type = 0x1275,
                .name = "PowerPC",
                .chrpdesc = {
                        .real_mode = ~0U,       /* ~0 means "don't care" */
                        .real_base = ~0U,
                        .real_size = ~0U,
                        .virt_base = ~0U,
                        .virt_size = ~0U,
                        .load_base = ~0U
                },
        },
        .rpanote = {
                .namesz = sizeof("IBM,RPA-Client-Config"),
                .descsz = sizeof(struct rpadesc),
                .type = 0x12759999,
                .name = "IBM,RPA-Client-Config",
                .rpadesc = {
                        .lpar_affinity = 0,
                        .min_rmo_size = 64,     /* in megabytes */
                        .min_rmo_percent = 0,
                        .max_pft_size = 48,     /* 2^48 bytes max PFT size */
                        .splpar = 1,
                        .min_load = ~0U,
                        .new_mem_def = 0
                }
        }
};

static void __init prom_send_capabilities(void)
{
        unsigned long offset = reloc_offset();
        ihandle elfloader;
        int ret;

        elfloader = call_prom("open", 1, 1, ADDR("/packages/elf-loader"));
        if (elfloader == 0) {
                prom_printf("couldn't open /packages/elf-loader\n");
                return;
        }
        ret = call_prom("call-method", 3, 1, ADDR("process-elf-header"),
                        elfloader, ADDR(&fake_elf));
        call_prom("close", 1, 0, elfloader);
}

/*
 * Memory allocation strategy... our layout is normally:
 *
 *  at 14Mb or more we vmlinux, then a gap and initrd. In some rare cases, initrd
 *  might end up beeing before the kernel though. We assume this won't override
 *  the final kernel at 0, we have no provision to handle that in this version,
 *  but it should hopefully never happen.
 *
 *  alloc_top is set to the top of RMO, eventually shrink down if the TCEs overlap
 *  alloc_bottom is set to the top of kernel/initrd
 *
 *  from there, allocations are done that way : rtas is allocated topmost, and
 *  the device-tree is allocated from the bottom. We try to grow the device-tree
 *  allocation as we progress. If we can't, then we fail, we don't currently have
 *  a facility to restart elsewhere, but that shouldn't be necessary neither
 *
 *  Note that calls to reserve_mem have to be done explicitely, memory allocated
 *  with either alloc_up or alloc_down isn't automatically reserved.
 */


/*
 * Allocates memory in the RMO upward from the kernel/initrd
 *
 * When align is 0, this is a special case, it means to allocate in place
 * at the current location of alloc_bottom or fail (that is basically
 * extending the previous allocation). Used for the device-tree flattening
 */
static unsigned long __init alloc_up(unsigned long size, unsigned long align)
{
        unsigned long offset = reloc_offset();
        unsigned long base = _ALIGN_UP(RELOC(alloc_bottom), align);
        unsigned long addr = 0;

        prom_debug("alloc_up(%x, %x)\n", size, align);
        if (RELOC(ram_top) == 0)
                prom_panic("alloc_up() called with mem not initialized\n");

        if (align)
                base = _ALIGN_UP(RELOC(alloc_bottom), align);
        else
                base = RELOC(alloc_bottom);

        for(; (base + size) <= RELOC(alloc_top); 
            base = _ALIGN_UP(base + 0x100000, align)) {
                prom_debug("    trying: 0x%x\n\r", base);
                addr = (unsigned long)prom_claim(base, size, 0);
                if ((int)addr != PROM_ERROR)
                        break;
                addr = 0;
                if (align == 0)
                        break;
        }
        if (addr == 0)
                return 0;
        RELOC(alloc_bottom) = addr;

        prom_debug(" -> %x\n", addr);
        prom_debug("  alloc_bottom : %x\n", RELOC(alloc_bottom));
        prom_debug("  alloc_top    : %x\n", RELOC(alloc_top));
        prom_debug("  alloc_top_hi : %x\n", RELOC(alloc_top_high));
        prom_debug("  rmo_top      : %x\n", RELOC(rmo_top));
        prom_debug("  ram_top      : %x\n", RELOC(ram_top));

        return addr;
}

/*
 * Allocates memory downard, either from top of RMO, or if highmem
 * is set, from the top of RAM. Note that this one doesn't handle
 * failures. In does claim memory if highmem is not set.
 */
static unsigned long __init alloc_down(unsigned long size, unsigned long align,
                                       int highmem)
{
        unsigned long offset = reloc_offset();
        unsigned long base, addr = 0;

        prom_debug("alloc_down(%x, %x, %s)\n", size, align,
                   highmem ? RELOC("(high)") : RELOC("(low)"));
        if (RELOC(ram_top) == 0)
                prom_panic("alloc_down() called with mem not initialized\n");

        if (highmem) {
                /* Carve out storage for the TCE table. */
                addr = _ALIGN_DOWN(RELOC(alloc_top_high) - size, align);
                if (addr <= RELOC(alloc_bottom))
                        return 0;
                else {
                        /* Will we bump into the RMO ? If yes, check out that we
                         * didn't overlap existing allocations there, if we did,
                         * we are dead, we must be the first in town !
                         */
                        if (addr < RELOC(rmo_top)) {
                                /* Good, we are first */
                                if (RELOC(alloc_top) == RELOC(rmo_top))
                                        RELOC(alloc_top) = RELOC(rmo_top) = addr;
                                else
                                        return 0;
                        }
                        RELOC(alloc_top_high) = addr;
                }
                goto bail;
        }

        base = _ALIGN_DOWN(RELOC(alloc_top) - size, align);
        for(; base > RELOC(alloc_bottom); base = _ALIGN_DOWN(base - 0x100000, align))  {
                prom_debug("    trying: 0x%x\n\r", base);
                addr = (unsigned long)prom_claim(base, size, 0);
                if ((int)addr != PROM_ERROR)
                        break;
                addr = 0;
        }
        if (addr == 0)
                return 0;
        RELOC(alloc_top) = addr;

 bail:
        prom_debug(" -> %x\n", addr);
        prom_debug("  alloc_bottom : %x\n", RELOC(alloc_bottom));
        prom_debug("  alloc_top    : %x\n", RELOC(alloc_top));
        prom_debug("  alloc_top_hi : %x\n", RELOC(alloc_top_high));
        prom_debug("  rmo_top      : %x\n", RELOC(rmo_top));
        prom_debug("  ram_top      : %x\n", RELOC(ram_top));

        return addr;
}

/*
 * Parse a "reg" cell
 */
static unsigned long __init prom_next_cell(int s, cell_t **cellp)
{
        cell_t *p = *cellp;
        unsigned long r = 0;

        /* Ignore more than 2 cells */
        while (s > 2) {
                p++;
                s--;
        }
        while (s) {
                r <<= 32;
                r |= *(p++);
                s--;
        }

        *cellp = p;
        return r;
}

/*
 * Very dumb function for adding to the memory reserve list, but
 * we don't need anything smarter at this point
 *
 * XXX Eventually check for collisions. They should NEVER happen
 * if problems seem to show up, it would be a good start to track
 * them down.
 */
static void reserve_mem(unsigned long base, unsigned long size)
{
        unsigned long offset = reloc_offset();
        unsigned long top = base + size;
        unsigned long cnt = RELOC(mem_reserve_cnt);

        if (size == 0)
                return;

        /* We need to always keep one empty entry so that we
         * have our terminator with "size" set to 0 since we are
         * dumb and just copy this entire array to the boot params
         */
        base = _ALIGN_DOWN(base, PAGE_SIZE);
        top = _ALIGN_UP(top, PAGE_SIZE);
        size = top - base;

        if (cnt >= (MEM_RESERVE_MAP_SIZE - 1))
                prom_panic("Memory reserve map exhausted !\n");
        RELOC(mem_reserve_map)[cnt].base = base;
        RELOC(mem_reserve_map)[cnt].size = size;
        RELOC(mem_reserve_cnt) = cnt + 1;
}

/*
 * Initialize memory allocation mecanism, parse "memory" nodes and
 * obtain that way the top of memory and RMO to setup out local allocator
 */
static void __init prom_init_mem(void)
{
        phandle node;
        char *path, type[64];
        unsigned int plen;
        cell_t *p, *endp;
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);

        /*
         * We iterate the memory nodes to find
         * 1) top of RMO (first node)
         * 2) top of memory
         */
        prom_debug("root_addr_cells: %x\n", (long)_prom->root_addr_cells);
        prom_debug("root_size_cells: %x\n", (long)_prom->root_size_cells);

        prom_debug("scanning memory:\n");
        path = RELOC(prom_scratch);

        for (node = 0; prom_next_node(&node); ) {
                type[0] = 0;
                prom_getprop(node, "device_type", type, sizeof(type));

                if (strcmp(type, RELOC("memory")))
                        continue;
        
                plen = prom_getprop(node, "reg", RELOC(regbuf), sizeof(regbuf));
                if (plen > sizeof(regbuf)) {
                        prom_printf("memory node too large for buffer !\n");
                        plen = sizeof(regbuf);
                }
                p = RELOC(regbuf);
                endp = p + (plen / sizeof(cell_t));

#ifdef DEBUG_PROM
                memset(path, 0, PROM_SCRATCH_SIZE);
                call_prom("package-to-path", 3, 1, node, path, PROM_SCRATCH_SIZE-1);
                prom_debug("  node %s :\n", path);
#endif /* DEBUG_PROM */

                while ((endp - p) >= (_prom->root_addr_cells + _prom->root_size_cells)) {
                        unsigned long base, size;

                        base = prom_next_cell(_prom->root_addr_cells, &p);
                        size = prom_next_cell(_prom->root_size_cells, &p);

                        if (size == 0)
                                continue;
                        prom_debug("    %x %x\n", base, size);
                        if (base == 0)
                                RELOC(rmo_top) = size;
                        if ((base + size) > RELOC(ram_top))
                                RELOC(ram_top) = base + size;
                }
        }

        RELOC(alloc_bottom) = PAGE_ALIGN(RELOC(klimit) - offset + 0x4000);

        /* Check if we have an initrd after the kernel, if we do move our bottom
         * point to after it
         */
        if (RELOC(prom_initrd_start)) {
                if (RELOC(prom_initrd_end) > RELOC(alloc_bottom))
                        RELOC(alloc_bottom) = PAGE_ALIGN(RELOC(prom_initrd_end));
        }

        /*
         * If prom_memory_limit is set we reduce the upper limits *except* for
         * alloc_top_high. This must be the real top of RAM so we can put
         * TCE's up there.
         */

        RELOC(alloc_top_high) = RELOC(ram_top);

        if (RELOC(prom_memory_limit)) {
                if (RELOC(prom_memory_limit) <= RELOC(alloc_bottom)) {
                        prom_printf("Ignoring mem=%x <= alloc_bottom.\n",
                                RELOC(prom_memory_limit));
                        RELOC(prom_memory_limit) = 0;
                } else if (RELOC(prom_memory_limit) >= RELOC(ram_top)) {
                        prom_printf("Ignoring mem=%x >= ram_top.\n",
                                RELOC(prom_memory_limit));
                        RELOC(prom_memory_limit) = 0;
                } else {
                        RELOC(ram_top) = RELOC(prom_memory_limit);
                        RELOC(rmo_top) = min(RELOC(rmo_top), RELOC(prom_memory_limit));
                }
        }

        /*
         * Setup our top alloc point, that is top of RMO or top of
         * segment 0 when running non-LPAR.
         */
        if ( RELOC(of_platform) == PLATFORM_PSERIES_LPAR )
                RELOC(alloc_top) = RELOC(rmo_top);
        else
                RELOC(alloc_top) = RELOC(rmo_top) = min(0x40000000ul, RELOC(ram_top));

        prom_printf("memory layout at init:\n");
        prom_printf("  memory_limit : %x (16 MB aligned)\n", RELOC(prom_memory_limit));
        prom_printf("  alloc_bottom : %x\n", RELOC(alloc_bottom));
        prom_printf("  alloc_top    : %x\n", RELOC(alloc_top));
        prom_printf("  alloc_top_hi : %x\n", RELOC(alloc_top_high));
        prom_printf("  rmo_top      : %x\n", RELOC(rmo_top));
        prom_printf("  ram_top      : %x\n", RELOC(ram_top));
}


/*
 * Allocate room for and instanciate RTAS
 */
static void __init prom_instantiate_rtas(void)
{
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        phandle prom_rtas, rtas_node;
        u32 base, entry = 0;
        u32 size = 0;

        prom_debug("prom_instantiate_rtas: start...\n");

        prom_rtas = call_prom("finddevice", 1, 1, ADDR("/rtas"));
        prom_debug("prom_rtas: %x\n", prom_rtas);
        if (prom_rtas == (phandle) -1)
                return;

        prom_getprop(prom_rtas, "rtas-size", &size, sizeof(size));
        if (size == 0)
                return;

        base = alloc_down(size, PAGE_SIZE, 0);
        if (base == 0) {
                prom_printf("RTAS allocation failed !\n");
                return;
        }
        prom_printf("instantiating rtas at 0x%x", base);

        rtas_node = call_prom("open", 1, 1, ADDR("/rtas"));
        prom_printf("...");

        if (call_prom("call-method", 3, 2,
                      ADDR("instantiate-rtas"),
                      rtas_node, base) != PROM_ERROR) {
                entry = (long)_prom->args.rets[1];
        }
        if (entry == 0) {
                prom_printf(" failed\n");
                return;
        }
        prom_printf(" done\n");

        reserve_mem(base, size);

        prom_setprop(prom_rtas, "linux,rtas-base", &base, sizeof(base));
        prom_setprop(prom_rtas, "linux,rtas-entry", &entry, sizeof(entry));

        prom_debug("rtas base     = 0x%x\n", base);
        prom_debug("rtas entry    = 0x%x\n", entry);
        prom_debug("rtas size     = 0x%x\n", (long)size);

        prom_debug("prom_instantiate_rtas: end...\n");
}


/*
 * Allocate room for and initialize TCE tables
 */
static void __init prom_initialize_tce_table(void)
{
        phandle node;
        ihandle phb_node;
        unsigned long offset = reloc_offset();
        char compatible[64], type[64], model[64];
        char *path = RELOC(prom_scratch);
        u64 base, align;
        u32 minalign, minsize;
        u64 tce_entry, *tce_entryp;
        u64 local_alloc_top, local_alloc_bottom;
        u64 i;

        if (RELOC(ppc64_iommu_off))
                return;

        prom_debug("starting prom_initialize_tce_table\n");

        /* Cache current top of allocs so we reserve a single block */
        local_alloc_top = RELOC(alloc_top_high);
        local_alloc_bottom = local_alloc_top;

        /* Search all nodes looking for PHBs. */
        for (node = 0; prom_next_node(&node); ) {
                compatible[0] = 0;
                type[0] = 0;
                model[0] = 0;
                prom_getprop(node, "compatible",
                             compatible, sizeof(compatible));
                prom_getprop(node, "device_type", type, sizeof(type));
                prom_getprop(node, "model", model, sizeof(model));

                if ((type[0] == 0) || (strstr(type, RELOC("pci")) == NULL))
                        continue;

                /* Keep the old logic in tack to avoid regression. */
                if (compatible[0] != 0) {
                        if ((strstr(compatible, RELOC("python")) == NULL) &&
                            (strstr(compatible, RELOC("Speedwagon")) == NULL) &&
                            (strstr(compatible, RELOC("Winnipeg")) == NULL))
                                continue;
                } else if (model[0] != 0) {
                        if ((strstr(model, RELOC("ython")) == NULL) &&
                            (strstr(model, RELOC("peedwagon")) == NULL) &&
                            (strstr(model, RELOC("innipeg")) == NULL))
                                continue;
                }

                if (prom_getprop(node, "tce-table-minalign", &minalign,
                                 sizeof(minalign)) == PROM_ERROR)
                        minalign = 0;
                if (prom_getprop(node, "tce-table-minsize", &minsize,
                                 sizeof(minsize)) == PROM_ERROR)
                        minsize = 4UL << 20;

                /*
                 * Even though we read what OF wants, we just set the table
                 * size to 4 MB.  This is enough to map 2GB of PCI DMA space.
                 * By doing this, we avoid the pitfalls of trying to DMA to
                 * MMIO space and the DMA alias hole.
                 *
                 * On POWER4, firmware sets the TCE region by assuming
                 * each TCE table is 8MB. Using this memory for anything
                 * else will impact performance, so we always allocate 8MB.
                 * Anton
                 */
                if (__is_processor(PV_POWER4) || __is_processor(PV_POWER4p))
                        minsize = 8UL << 20;
                else
                        minsize = 4UL << 20;

                /* Align to the greater of the align or size */
                align = max(minalign, minsize);
                base = alloc_down(minsize, align, 1);
                if (base == 0)
                        prom_panic("ERROR, cannot find space for TCE table.\n");
                if (base < local_alloc_bottom)
                        local_alloc_bottom = base;

                /* Save away the TCE table attributes for later use. */
                prom_setprop(node, "linux,tce-base", &base, sizeof(base));
                prom_setprop(node, "linux,tce-size", &minsize, sizeof(minsize));

                /* It seems OF doesn't null-terminate the path :-( */
                memset(path, 0, sizeof(path));
                /* Call OF to setup the TCE hardware */
                if (call_prom("package-to-path", 3, 1, node,
                              path, PROM_SCRATCH_SIZE-1) == PROM_ERROR) {
                        prom_printf("package-to-path failed\n");
                }

                prom_debug("TCE table: %s\n", path);
                prom_debug("\tnode = 0x%x\n", node);
                prom_debug("\tbase = 0x%x\n", base);
                prom_debug("\tsize = 0x%x\n", minsize);

                /* Initialize the table to have a one-to-one mapping
                 * over the allocated size.
                 */
                tce_entryp = (unsigned long *)base;
                for (i = 0; i < (minsize >> 3) ;tce_entryp++, i++) {
                        tce_entry = (i << PAGE_SHIFT);
                        tce_entry |= 0x3;
                        *tce_entryp = tce_entry;
                }

                prom_printf("opening PHB %s", path);
                phb_node = call_prom("open", 1, 1, path);
                if ( (long)phb_node <= 0)
                        prom_printf("... failed\n");
                else
                        prom_printf("... done\n");

                call_prom("call-method", 6, 0, ADDR("set-64-bit-addressing"),
                          phb_node, -1, minsize,
                          (u32) base, (u32) (base >> 32));
                call_prom("close", 1, 0, phb_node);
        }

        reserve_mem(local_alloc_bottom, local_alloc_top - local_alloc_bottom);

        if (RELOC(prom_memory_limit)) {
                /*
                 * We align the start to a 16MB boundary so we can map the TCE area
                 * using large pages if possible. The end should be the top of RAM
                 * so no need to align it.
                 */
                RELOC(prom_tce_alloc_start) = _ALIGN_DOWN(local_alloc_bottom, 0x1000000);
                RELOC(prom_tce_alloc_end) = local_alloc_top;
        }

        /* Flag the first invalid entry */
        prom_debug("ending prom_initialize_tce_table\n");
}

/*
 * With CHRP SMP we need to use the OF to start the other
 * processors so we can't wait until smp_boot_cpus (the OF is
 * trashed by then) so we have to put the processors into
 * a holding pattern controlled by the kernel (not OF) before
 * we destroy the OF.
 *
 * This uses a chunk of low memory, puts some holding pattern
 * code there and sends the other processors off to there until
 * smp_boot_cpus tells them to do something.  The holding pattern
 * checks that address until its cpu # is there, when it is that
 * cpu jumps to __secondary_start().  smp_boot_cpus() takes care
 * of setting those values.
 *
 * We also use physical address 0x4 here to tell when a cpu
 * is in its holding pattern code.
 *
 * Fixup comment... DRENG / PPPBBB - Peter
 *
 * -- Cort
 */
static void __init prom_hold_cpus(void)
{
        unsigned long i;
        unsigned int reg;
        phandle node;
        unsigned long offset = reloc_offset();
        char type[64];
        int cpuid = 0;
        unsigned int interrupt_server[MAX_CPU_THREADS];
        unsigned int cpu_threads, hw_cpu_num;
        int propsize;
        extern void __secondary_hold(void);
        extern unsigned long __secondary_hold_spinloop;
        extern unsigned long __secondary_hold_acknowledge;
        unsigned long *spinloop
                = (void *)virt_to_abs(&__secondary_hold_spinloop);
        unsigned long *acknowledge
                = (void *)virt_to_abs(&__secondary_hold_acknowledge);
        unsigned long secondary_hold
                = virt_to_abs(*PTRRELOC((unsigned long *)__secondary_hold));
        struct prom_t *_prom = PTRRELOC(&prom);

        prom_debug("prom_hold_cpus: start...\n");
        prom_debug("    1) spinloop       = 0x%x\n", (unsigned long)spinloop);
        prom_debug("    1) *spinloop      = 0x%x\n", *spinloop);
        prom_debug("    1) acknowledge    = 0x%x\n",
                   (unsigned long)acknowledge);
        prom_debug("    1) *acknowledge   = 0x%x\n", *acknowledge);
        prom_debug("    1) secondary_hold = 0x%x\n", secondary_hold);

        /* Set the common spinloop variable, so all of the secondary cpus
         * will block when they are awakened from their OF spinloop.
         * This must occur for both SMP and non SMP kernels, since OF will
         * be trashed when we move the kernel.
         */
        *spinloop = 0;

#ifdef CONFIG_HMT
        for (i=0; i < NR_CPUS; i++) {
                RELOC(hmt_thread_data)[i].pir = 0xdeadbeef;
        }
#endif
        /* look for cpus */
        for (node = 0; prom_next_node(&node); ) {
                type[0] = 0;
                prom_getprop(node, "device_type", type, sizeof(type));
                if (strcmp(type, RELOC("cpu")) != 0)
                        continue;

                /* Skip non-configured cpus. */
                if (prom_getprop(node, "status", type, sizeof(type)) > 0)
                        if (strcmp(type, RELOC("okay")) != 0)
                                continue;

                reg = -1;
                prom_getprop(node, "reg", &reg, sizeof(reg));

                prom_debug("\ncpuid        = 0x%x\n", cpuid);
                prom_debug("cpu hw idx   = 0x%x\n", reg);

                /* Init the acknowledge var which will be reset by
                 * the secondary cpu when it awakens from its OF
                 * spinloop.
                 */
                *acknowledge = (unsigned long)-1;

                propsize = prom_getprop(node, "ibm,ppc-interrupt-server#s",
                                        &interrupt_server,
                                        sizeof(interrupt_server));
                if (propsize < 0) {
                        /* no property.  old hardware has no SMT */
                        cpu_threads = 1;
                        interrupt_server[0] = reg; /* fake it with phys id */
                } else {
                        /* We have a threaded processor */
                        cpu_threads = propsize / sizeof(u32);
                        if (cpu_threads > MAX_CPU_THREADS) {
                                prom_printf("SMT: too many threads!\n"
                                            "SMT: found %x, max is %x\n",
                                            cpu_threads, MAX_CPU_THREADS);
                                cpu_threads = 1; /* ToDo: panic? */
                        }
                }

                hw_cpu_num = interrupt_server[0];
                if (hw_cpu_num != _prom->cpu) {
                        /* Primary Thread of non-boot cpu */
                        prom_printf("%x : starting cpu hw idx %x... ", cpuid, reg);
                        call_prom("start-cpu", 3, 0, node,
                                  secondary_hold, reg);

                        for ( i = 0 ; (i < 100000000) && 
                              (*acknowledge == ((unsigned long)-1)); i++ )
                                mb();

                        if (*acknowledge == reg) {
                                prom_printf("done\n");
                                /* We have to get every CPU out of OF,
                                 * even if we never start it. */
                                if (cpuid >= NR_CPUS)
                                        goto next;
                        } else {
                                prom_printf("failed: %x\n", *acknowledge);
                        }
                }
#ifdef CONFIG_SMP
                else
                        prom_printf("%x : boot cpu     %x\n", cpuid, reg);
#endif
next:
#ifdef CONFIG_SMP
                /* Init paca for secondary threads.   They start later. */
                for (i=1; i < cpu_threads; i++) {
                        cpuid++;
                        if (cpuid >= NR_CPUS)
                                continue;
                }
#endif /* CONFIG_SMP */
                cpuid++;
        }
#ifdef CONFIG_HMT
        /* Only enable HMT on processors that provide support. */
        if (__is_processor(PV_PULSAR) || 
            __is_processor(PV_ICESTAR) ||
            __is_processor(PV_SSTAR)) {
                prom_printf("    starting secondary threads\n");

                for (i = 0; i < NR_CPUS; i += 2) {
                        if (!cpu_online(i))
                                continue;

                        if (i == 0) {
                                unsigned long pir = mfspr(SPRN_PIR);
                                if (__is_processor(PV_PULSAR)) {
                                        RELOC(hmt_thread_data)[i].pir = 
                                                pir & 0x1f;
                                } else {
                                        RELOC(hmt_thread_data)[i].pir = 
                                                pir & 0x3ff;
                                }
                        }
                }
        } else {
                prom_printf("Processor is not HMT capable\n");
        }
#endif

        if (cpuid > NR_CPUS)
                prom_printf("WARNING: maximum CPUs (" __stringify(NR_CPUS)
                            ") exceeded: ignoring extras\n");

        prom_debug("prom_hold_cpus: end...\n");
}


static void __init prom_init_client_services(unsigned long pp)
{
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);

        /* Get a handle to the prom entry point before anything else */
        _prom->entry = pp;

        /* Init default value for phys size */
        _prom->root_size_cells = 1;
        _prom->root_addr_cells = 2;

        /* get a handle for the stdout device */
        _prom->chosen = call_prom("finddevice", 1, 1, ADDR("/chosen"));
        if ((long)_prom->chosen <= 0)
                prom_panic("cannot find chosen"); /* msg won't be printed :( */

        /* get device tree root */
        _prom->root = call_prom("finddevice", 1, 1, ADDR("/"));
        if ((long)_prom->root <= 0)
                prom_panic("cannot find device tree root"); /* msg won't be printed :( */
}

static void __init prom_init_stdout(void)
{
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        char *path = RELOC(of_stdout_device);
        char type[16];
        u32 val;

        if (prom_getprop(_prom->chosen, "stdout", &val, sizeof(val)) <= 0)
                prom_panic("cannot find stdout");

        _prom->stdout = val;

        /* Get the full OF pathname of the stdout device */
        memset(path, 0, 256);
        call_prom("instance-to-path", 3, 1, _prom->stdout, path, 255);
        val = call_prom("instance-to-package", 1, 1, _prom->stdout);
        prom_setprop(_prom->chosen, "linux,stdout-package", &val, sizeof(val));
        prom_printf("OF stdout device is: %s\n", RELOC(of_stdout_device));
        prom_setprop(_prom->chosen, "linux,stdout-path",
                     RELOC(of_stdout_device), strlen(RELOC(of_stdout_device))+1);

        /* If it's a display, note it */
        memset(type, 0, sizeof(type));
        prom_getprop(val, "device_type", type, sizeof(type));
        if (strcmp(type, RELOC("display")) == 0) {
                _prom->disp_node = val;
                prom_setprop(val, "linux,boot-display", NULL, 0);
        }
}

static void __init prom_close_stdin(void)
{
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        ihandle val;

        if (prom_getprop(_prom->chosen, "stdin", &val, sizeof(val)) > 0)
                call_prom("close", 1, 0, val);
}

static int __init prom_find_machine_type(void)
{
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        char compat[256];
        int len, i = 0;
        phandle rtas;

        len = prom_getprop(_prom->root, "compatible",
                           compat, sizeof(compat)-1);
        if (len > 0) {
                compat[len] = 0;
                while (i < len) {
                        char *p = &compat[i];
                        int sl = strlen(p);
                        if (sl == 0)
                                break;
                        if (strstr(p, RELOC("Power Macintosh")) ||
                            strstr(p, RELOC("MacRISC4")))
                                return PLATFORM_POWERMAC;
                        if (strstr(p, RELOC("Momentum,Maple")))
                                return PLATFORM_MAPLE;
                        i += sl + 1;
                }
        }
        /* Default to pSeries. We need to know if we are running LPAR */
        rtas = call_prom("finddevice", 1, 1, ADDR("/rtas"));
        if (rtas != (phandle) -1) {
                unsigned long x;
                x = prom_getproplen(rtas, "ibm,hypertas-functions");
                if (x != PROM_ERROR) {
                        prom_printf("Hypertas detected, assuming LPAR !\n");
                        return PLATFORM_PSERIES_LPAR;
                }
        }
        return PLATFORM_PSERIES;
}

static int __init prom_set_color(ihandle ih, int i, int r, int g, int b)
{
        unsigned long offset = reloc_offset();

        return call_prom("call-method", 6, 1, ADDR("color!"), ih, i, b, g, r);
}

/*
 * If we have a display that we don't know how to drive,
 * we will want to try to execute OF's open method for it
 * later.  However, OF will probably fall over if we do that
 * we've taken over the MMU.
 * So we check whether we will need to open the display,
 * and if so, open it now.
 */
static void __init prom_check_displays(void)
{
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        char type[16], *path;
        phandle node;
        ihandle ih;
        int i;

        static unsigned char default_colors[] = {
                0x00, 0x00, 0x00,
                0x00, 0x00, 0xaa,
                0x00, 0xaa, 0x00,
                0x00, 0xaa, 0xaa,
                0xaa, 0x00, 0x00,
                0xaa, 0x00, 0xaa,
                0xaa, 0xaa, 0x00,
                0xaa, 0xaa, 0xaa,
                0x55, 0x55, 0x55,
                0x55, 0x55, 0xff,
                0x55, 0xff, 0x55,
                0x55, 0xff, 0xff,
                0xff, 0x55, 0x55,
                0xff, 0x55, 0xff,
                0xff, 0xff, 0x55,
                0xff, 0xff, 0xff
        };
        const unsigned char *clut;

        prom_printf("Looking for displays\n");
        for (node = 0; prom_next_node(&node); ) {
                memset(type, 0, sizeof(type));
                prom_getprop(node, "device_type", type, sizeof(type));
                if (strcmp(type, RELOC("display")) != 0)
                        continue;

                /* It seems OF doesn't null-terminate the path :-( */
                path = RELOC(prom_scratch);
                memset(path, 0, PROM_SCRATCH_SIZE);

                /*
                 * leave some room at the end of the path for appending extra
                 * arguments
                 */
                if (call_prom("package-to-path", 3, 1, node, path, PROM_SCRATCH_SIZE-10) < 0)
                        continue;
                prom_printf("found display   : %s, opening ... ", path);
                
                ih = call_prom("open", 1, 1, path);
                if (ih == (ihandle)0 || ih == (ihandle)-1) {
                        prom_printf("failed\n");
                        continue;
                }

                /* Success */
                prom_printf("done\n");
                prom_setprop(node, "linux,opened", NULL, 0);

                /*
                 * stdout wasn't a display node, pick the first we can find
                 * for btext
                 */
                if (_prom->disp_node == 0)
                        _prom->disp_node = node;

                /* Setup a useable color table when the appropriate
                 * method is available. Should update this to set-colors */
                clut = RELOC(default_colors);
                for (i = 0; i < 32; i++, clut += 3)
                        if (prom_set_color(ih, i, clut[0], clut[1],
                                           clut[2]) != 0)
                                break;

#ifdef CONFIG_LOGO_LINUX_CLUT224
                clut = PTRRELOC(RELOC(logo_linux_clut224.clut));
                for (i = 0; i < RELOC(logo_linux_clut224.clutsize); i++, clut += 3)
                        if (prom_set_color(ih, i + 32, clut[0], clut[1],
                                           clut[2]) != 0)
                                break;
#endif /* CONFIG_LOGO_LINUX_CLUT224 */
        }
}


/* Return (relocated) pointer to this much memory: moves initrd if reqd. */
static void __init *make_room(unsigned long *mem_start, unsigned long *mem_end,
                              unsigned long needed, unsigned long align)
{
        unsigned long offset = reloc_offset();
        void *ret;

        *mem_start = _ALIGN(*mem_start, align);
        while ((*mem_start + needed) > *mem_end) {
                unsigned long room, chunk;

                prom_debug("Chunk exhausted, claiming more at %x...\n",
                           RELOC(alloc_bottom));
                room = RELOC(alloc_top) - RELOC(alloc_bottom);
                if (room > DEVTREE_CHUNK_SIZE)
                        room = DEVTREE_CHUNK_SIZE;
                if (room < PAGE_SIZE)
                        prom_panic("No memory for flatten_device_tree (no room)");
                chunk = alloc_up(room, 0);
                if (chunk == 0)
                        prom_panic("No memory for flatten_device_tree (claim failed)");
                *mem_end = RELOC(alloc_top);
        }

        ret = (void *)*mem_start;
        *mem_start += needed;

        return ret;
}

#define dt_push_token(token, mem_start, mem_end) \
        do { *((u32 *)make_room(mem_start, mem_end, 4, 4)) = token; } while(0)

static unsigned long __init dt_find_string(char *str)
{
        unsigned long offset = reloc_offset();
        char *s, *os;

        s = os = (char *)RELOC(dt_string_start);
        s += 4;
        while (s <  (char *)RELOC(dt_string_end)) {
                if (strcmp(s, str) == 0)
                        return s - os;
                s += strlen(s) + 1;
        }
        return 0;
}

static void __init scan_dt_build_strings(phandle node, unsigned long *mem_start,
                                         unsigned long *mem_end)
{
        unsigned long offset = reloc_offset();
        char *prev_name, *namep, *sstart;
        unsigned long soff;
        phandle child;

        sstart =  (char *)RELOC(dt_string_start);

        /* get and store all property names */
        prev_name = RELOC("");
        for (;;) {
                
                /* 32 is max len of name including nul. */
                namep = make_room(mem_start, mem_end, 32, 1);
                if (call_prom("nextprop", 3, 1, node, prev_name, namep) <= 0) {
                        /* No more nodes: unwind alloc */
                        *mem_start = (unsigned long)namep;
                        break;
                }
                soff = dt_find_string(namep);
                if (soff != 0) {
                        *mem_start = (unsigned long)namep;
                        namep = sstart + soff;
                } else {
                        /* Trim off some if we can */
                        *mem_start = (unsigned long)namep + strlen(namep) + 1;
                        RELOC(dt_string_end) = *mem_start;
                }
                prev_name = namep;
        }

        /* do all our children */
        child = call_prom("child", 1, 1, node);
        while (child != (phandle)0) {
                scan_dt_build_strings(child, mem_start, mem_end);
                child = call_prom("peer", 1, 1, child);
        }
}

/*
 * The Open Firmware 1275 specification states properties must be 31 bytes or
 * less, however not all firmwares obey this. Make it 64 bytes to be safe.
 */
#define MAX_PROPERTY_NAME 64

static void __init scan_dt_build_struct(phandle node, unsigned long *mem_start,
                                        unsigned long *mem_end)
{
        int l, align;
        phandle child;
        char *namep, *prev_name, *sstart;
        unsigned long soff;
        unsigned char *valp;
        unsigned long offset = reloc_offset();
        char pname[MAX_PROPERTY_NAME];
        char *path;

        path = RELOC(prom_scratch);

        dt_push_token(OF_DT_BEGIN_NODE, mem_start, mem_end);

        /* get the node's full name */
        namep = (char *)*mem_start;
        l = call_prom("package-to-path", 3, 1, node,
                      namep, *mem_end - *mem_start);
        if (l >= 0) {
                /* Didn't fit?  Get more room. */
                if (l+1 > *mem_end - *mem_start) {
                        namep = make_room(mem_start, mem_end, l+1, 1);
                        call_prom("package-to-path", 3, 1, node, namep, l);
                }
                namep[l] = '\0';
                *mem_start = _ALIGN(((unsigned long) namep) + strlen(namep) + 1, 4);
        }

        /* get it again for debugging */
        memset(path, 0, PROM_SCRATCH_SIZE);
        call_prom("package-to-path", 3, 1, node, path, PROM_SCRATCH_SIZE-1);

        /* get and store all properties */
        prev_name = RELOC("");
        sstart = (char *)RELOC(dt_string_start);
        for (;;) {
                if (call_prom("nextprop", 3, 1, node, prev_name, pname) <= 0)
                        break;

                /* find string offset */
                soff = dt_find_string(pname);
                if (soff == 0) {
                        prom_printf("WARNING: Can't find string index for <%s>, node %s\n",
                                    pname, path);
                        break;
                }
                prev_name = sstart + soff;

                /* get length */
                l = call_prom("getproplen", 2, 1, node, pname);

                /* sanity checks */
                if (l < 0)
                        continue;
                if (l > MAX_PROPERTY_LENGTH) {
                        prom_printf("WARNING: ignoring large property ");
                        /* It seems OF doesn't null-terminate the path :-( */
                        prom_printf("[%s] ", path);
                        prom_printf("%s length 0x%x\n", pname, l);
                        continue;
                }

                /* push property head */
                dt_push_token(OF_DT_PROP, mem_start, mem_end);
                dt_push_token(l, mem_start, mem_end);
                dt_push_token(soff, mem_start, mem_end);

                /* push property content */
                align = (l >= 8) ? 8 : 4;
                valp = make_room(mem_start, mem_end, l, align);
                call_prom("getprop", 4, 1, node, pname, valp, l);
                *mem_start = _ALIGN(*mem_start, 4);
        }

        /* Add a "linux,phandle" property. */
        soff = dt_find_string(RELOC("linux,phandle"));
        if (soff == 0)
                prom_printf("WARNING: Can't find string index for <linux-phandle>"
                            " node %s\n", path);
        else {
                dt_push_token(OF_DT_PROP, mem_start, mem_end);
                dt_push_token(4, mem_start, mem_end);
                dt_push_token(soff, mem_start, mem_end);
                valp = make_room(mem_start, mem_end, 4, 4);
                *(u32 *)valp = node;
        }

        /* do all our children */
        child = call_prom("child", 1, 1, node);
        while (child != (phandle)0) {
                scan_dt_build_struct(child, mem_start, mem_end);
                child = call_prom("peer", 1, 1, child);
        }

        dt_push_token(OF_DT_END_NODE, mem_start, mem_end);
}

static void __init flatten_device_tree(void)
{
        phandle root;
        unsigned long offset = reloc_offset();
        unsigned long mem_start, mem_end, room;
        struct boot_param_header *hdr;
        char *namep;
        u64 *rsvmap;

        /*
         * Check how much room we have between alloc top & bottom (+/- a
         * few pages), crop to 4Mb, as this is our "chuck" size
         */
        room = RELOC(alloc_top) - RELOC(alloc_bottom) - 0x4000;
        if (room > DEVTREE_CHUNK_SIZE)
                room = DEVTREE_CHUNK_SIZE;
        prom_debug("starting device tree allocs at %x\n", RELOC(alloc_bottom));

        /* Now try to claim that */
        mem_start = (unsigned long)alloc_up(room, PAGE_SIZE);
        if (mem_start == 0)
                prom_panic("Can't allocate initial device-tree chunk\n");
        mem_end = RELOC(alloc_top);

        /* Get root of tree */
        root = call_prom("peer", 1, 1, (phandle)0);
        if (root == (phandle)0)
                prom_panic ("couldn't get device tree root\n");

        /* Build header and make room for mem rsv map */ 
        mem_start = _ALIGN(mem_start, 4);
        hdr = make_room(&mem_start, &mem_end, sizeof(struct boot_param_header), 4);
        RELOC(dt_header_start) = (unsigned long)hdr;
        rsvmap = make_room(&mem_start, &mem_end, sizeof(mem_reserve_map), 8);

        /* Start of strings */
        mem_start = PAGE_ALIGN(mem_start);
        RELOC(dt_string_start) = mem_start;
        mem_start += 4; /* hole */

        /* Add "linux,phandle" in there, we'll need it */
        namep = make_room(&mem_start, &mem_end, 16, 1);
        strcpy(namep, RELOC("linux,phandle"));
        mem_start = (unsigned long)namep + strlen(namep) + 1;
        RELOC(dt_string_end) = mem_start;

        /* Build string array */
        prom_printf("Building dt strings...\n"); 
        scan_dt_build_strings(root, &mem_start, &mem_end);

        /* Build structure */
        mem_start = PAGE_ALIGN(mem_start);
        RELOC(dt_struct_start) = mem_start;
        prom_printf("Building dt structure...\n"); 
        scan_dt_build_struct(root, &mem_start, &mem_end);
        dt_push_token(OF_DT_END, &mem_start, &mem_end);
        RELOC(dt_struct_end) = PAGE_ALIGN(mem_start);

        /* Finish header */
        hdr->magic = OF_DT_HEADER;
        hdr->totalsize = RELOC(dt_struct_end) - RELOC(dt_header_start);
        hdr->off_dt_struct = RELOC(dt_struct_start) - RELOC(dt_header_start);
        hdr->off_dt_strings = RELOC(dt_string_start) - RELOC(dt_header_start);
        hdr->off_mem_rsvmap = ((unsigned long)rsvmap) - RELOC(dt_header_start);
        hdr->version = OF_DT_VERSION;
        hdr->last_comp_version = 1;

        /* Reserve the whole thing and copy the reserve map in, we
         * also bump mem_reserve_cnt to cause further reservations to
         * fail since it's too late.
         */
        reserve_mem(RELOC(dt_header_start), hdr->totalsize);
        memcpy(rsvmap, RELOC(mem_reserve_map), sizeof(mem_reserve_map));

#ifdef DEBUG_PROM
        {
                int i;
                prom_printf("reserved memory map:\n");
                for (i = 0; i < RELOC(mem_reserve_cnt); i++)
                        prom_printf("  %x - %x\n", RELOC(mem_reserve_map)[i].base,
                                    RELOC(mem_reserve_map)[i].size);
        }
#endif
        RELOC(mem_reserve_cnt) = MEM_RESERVE_MAP_SIZE;

        prom_printf("Device tree strings 0x%x -> 0x%x\n",
                    RELOC(dt_string_start), RELOC(dt_string_end)); 
        prom_printf("Device tree struct  0x%x -> 0x%x\n",
                    RELOC(dt_struct_start), RELOC(dt_struct_end));

 }

static void __init prom_find_boot_cpu(void)
{
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        u32 getprop_rval;
        ihandle prom_cpu;
        phandle cpu_pkg;

        if (prom_getprop(_prom->chosen, "cpu", &prom_cpu, sizeof(prom_cpu)) <= 0)
                prom_panic("cannot find boot cpu");

        cpu_pkg = call_prom("instance-to-package", 1, 1, prom_cpu);

        prom_setprop(cpu_pkg, "linux,boot-cpu", NULL, 0);
        prom_getprop(cpu_pkg, "reg", &getprop_rval, sizeof(getprop_rval));
        _prom->cpu = getprop_rval;

        prom_debug("Booting CPU hw index = 0x%x\n", _prom->cpu);
}

static void __init prom_check_initrd(unsigned long r3, unsigned long r4)
{
#ifdef CONFIG_BLK_DEV_INITRD
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);

        if ( r3 && r4 && r4 != 0xdeadbeef) {
                u64 val;

                RELOC(prom_initrd_start) = (r3 >= KERNELBASE) ? __pa(r3) : r3;
                RELOC(prom_initrd_end) = RELOC(prom_initrd_start) + r4;

                val = (u64)RELOC(prom_initrd_start);
                prom_setprop(_prom->chosen, "linux,initrd-start", &val, sizeof(val));
                val = (u64)RELOC(prom_initrd_end);
                prom_setprop(_prom->chosen, "linux,initrd-end", &val, sizeof(val));

                reserve_mem(RELOC(prom_initrd_start),
                            RELOC(prom_initrd_end) - RELOC(prom_initrd_start));

                prom_debug("initrd_start=0x%x\n", RELOC(prom_initrd_start));
                prom_debug("initrd_end=0x%x\n", RELOC(prom_initrd_end));
        }
#endif /* CONFIG_BLK_DEV_INITRD */
}

/*
 * We enter here early on, when the Open Firmware prom is still
 * handling exceptions and the MMU hash table for us.
 */

unsigned long __init prom_init(unsigned long r3, unsigned long r4, unsigned long pp,
                               unsigned long r6, unsigned long r7)
{       
        unsigned long offset = reloc_offset();
        struct prom_t *_prom = PTRRELOC(&prom);
        unsigned long phys = KERNELBASE - offset;
        u32 getprop_rval;
        
        /*
         * First zero the BSS
         */
        memset(PTRRELOC(&__bss_start), 0, __bss_stop - __bss_start);

        /*
         * Init interface to Open Firmware, get some node references,
         * like /chosen
         */
        prom_init_client_services(pp);

        /*
         * Init prom stdout device
         */
        prom_init_stdout();
        prom_debug("klimit=0x%x\n", RELOC(klimit));
        prom_debug("offset=0x%x\n", offset);

        /*
         * Check for an initrd
         */
        prom_check_initrd(r3, r4);

        /*
         * Get default machine type. At this point, we do not differenciate
         * between pSeries SMP and pSeries LPAR
         */
        RELOC(of_platform) = prom_find_machine_type();
        getprop_rval = RELOC(of_platform);
        prom_setprop(_prom->chosen, "linux,platform",
                     &getprop_rval, sizeof(getprop_rval));

        /*
         * On pSeries, copy the CPU hold code
         */
        if (RELOC(of_platform) & PLATFORM_PSERIES)
                copy_and_flush(0, KERNELBASE - offset, 0x100, 0);

        /*
         * Get memory cells format
         */
        getprop_rval = 1;
        prom_getprop(_prom->root, "#size-cells",
                     &getprop_rval, sizeof(getprop_rval));
        _prom->root_size_cells = getprop_rval;
        getprop_rval = 2;
        prom_getprop(_prom->root, "#address-cells",
                     &getprop_rval, sizeof(getprop_rval));
        _prom->root_addr_cells = getprop_rval;

        /*
         * Do early parsing of command line
         */
        early_cmdline_parse();

        /*
         * Initialize memory management within prom_init
         */
        prom_init_mem();

        /*
         * Determine which cpu is actually running right _now_
         */
        prom_find_boot_cpu();

        /* 
         * Initialize display devices
         */
        prom_check_displays();

        /*
         * Initialize IOMMU (TCE tables) on pSeries. Do that before anything else
         * that uses the allocator, we need to make sure we get the top of memory
         * available for us here...
         */
        if (RELOC(of_platform) == PLATFORM_PSERIES)
                prom_initialize_tce_table();

        /*
         * On non-powermacs, try to instantiate RTAS and puts all CPUs
         * in spin-loops. PowerMacs don't have a working RTAS and use
         * a different way to spin CPUs
         */
        if (RELOC(of_platform) != PLATFORM_POWERMAC) {
                prom_instantiate_rtas();
                prom_hold_cpus();
        }

        /*
         * Fill in some infos for use by the kernel later on
         */
        if (RELOC(ppc64_iommu_off))
                prom_setprop(_prom->chosen, "linux,iommu-off", NULL, 0);

        if (RELOC(iommu_force_on))
                prom_setprop(_prom->chosen, "linux,iommu-force-on", NULL, 0);

        if (RELOC(prom_memory_limit))
                prom_setprop(_prom->chosen, "linux,memory-limit",
                        PTRRELOC(&prom_memory_limit), sizeof(RELOC(prom_memory_limit)));

        if (RELOC(prom_tce_alloc_start)) {
                prom_setprop(_prom->chosen, "linux,tce-alloc-start",
                        PTRRELOC(&prom_tce_alloc_start), sizeof(RELOC(prom_tce_alloc_start)));
                prom_setprop(_prom->chosen, "linux,tce-alloc-end",
                        PTRRELOC(&prom_tce_alloc_end), sizeof(RELOC(prom_tce_alloc_end)));
        }

        /*
         * Now finally create the flattened device-tree
         */
        prom_printf("copying OF device tree ...\n");
        flatten_device_tree();

        /* in case stdin is USB and still active on IBM machines... */
        prom_close_stdin();

        /*
         * Call OF "quiesce" method to shut down pending DMA's from
         * devices etc...
         */
        prom_printf("Calling quiesce ...\n");
        call_prom("quiesce", 0, 0);

        /*
         * And finally, call the kernel passing it the flattened device
         * tree and NULL as r5, thus triggering the new entry point which
         * is common to us and kexec
         */
        prom_printf("returning from prom_init\n");
        prom_debug("->dt_header_start=0x%x\n", RELOC(dt_header_start));
        prom_debug("->phys=0x%x\n", phys);

        __start(RELOC(dt_header_start), phys, 0);

        return 0;
}