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prom.c

/*
 * Procedures for creating, accessing and interpreting the device tree.
 *
 * Paul Mackerras August 1996.
 * Copyright (C) 1996-2005 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.
 */

#include <stdarg.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/threads.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/pci.h>
#include <linux/stringify.h>
#include <linux/delay.h>
#include <linux/initrd.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/debugfs.h>
#include <linux/irq.h>
#include <linux/lmb.h>

#include <asm/prom.h>
#include <asm/page.h>
#include <asm/processor.h>
#include <asm/irq.h>
#include <linux/io.h>
#include <asm/system.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/pci-bridge.h>

static int __initdata dt_root_addr_cells;
static int __initdata dt_root_size_cells;

typedef u32 cell_t;

static struct boot_param_header *initial_boot_params;

/* export that to outside world */
struct device_node *of_chosen;

static inline char *find_flat_dt_string(u32 offset)
{
      return ((char *)initial_boot_params) +
            initial_boot_params->off_dt_strings + offset;
}

/**
 * This function is used to scan the flattened device-tree, it is
 * used to extract the memory informations at boot before we can
 * unflatten the tree
 */
int __init of_scan_flat_dt(int (*it)(unsigned long node,
                             const char *uname, int depth,
                             void *data),
                     void *data)
{
      unsigned long p = ((unsigned long)initial_boot_params) +
            initial_boot_params->off_dt_struct;
      int rc = 0;
      int depth = -1;

      do {
            u32 tag = *((u32 *)p);
            char *pathp;

            p += 4;
            if (tag == OF_DT_END_NODE) {
                  depth--;
                  continue;
            }
            if (tag == OF_DT_NOP)
                  continue;
            if (tag == OF_DT_END)
                  break;
            if (tag == OF_DT_PROP) {
                  u32 sz = *((u32 *)p);
                  p += 8;
                  if (initial_boot_params->version < 0x10)
                        p = _ALIGN(p, sz >= 8 ? 8 : 4);
                  p += sz;
                  p = _ALIGN(p, 4);
                  continue;
            }
            if (tag != OF_DT_BEGIN_NODE) {
                  printk(KERN_WARNING "Invalid tag %x scanning flattened"
                        " device tree !\n", tag);
                  return -EINVAL;
            }
            depth++;
            pathp = (char *)p;
            p = _ALIGN(p + strlen(pathp) + 1, 4);
            if ((*pathp) == '/') {
                  char *lp, *np;
                  for (lp = NULL, np = pathp; *np; np++)
                        if ((*np) == '/')
                              lp = np+1;
                  if (lp != NULL)
                        pathp = lp;
            }
            rc = it(p, pathp, depth, data);
            if (rc != 0)
                  break;
      } while (1);

      return rc;
}

unsigned long __init of_get_flat_dt_root(void)
{
      unsigned long p = ((unsigned long)initial_boot_params) +
            initial_boot_params->off_dt_struct;

      while (*((u32 *)p) == OF_DT_NOP)
            p += 4;
      BUG_ON(*((u32 *)p) != OF_DT_BEGIN_NODE);
      p += 4;
      return _ALIGN(p + strlen((char *)p) + 1, 4);
}

/**
 * This function can be used within scan_flattened_dt callback to get
 * access to properties
 */
void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
                        unsigned long *size)
{
      unsigned long p = node;

      do {
            u32 tag = *((u32 *)p);
            u32 sz, noff;
            const char *nstr;

            p += 4;
            if (tag == OF_DT_NOP)
                  continue;
            if (tag != OF_DT_PROP)
                  return NULL;

            sz = *((u32 *)p);
            noff = *((u32 *)(p + 4));
            p += 8;
            if (initial_boot_params->version < 0x10)
                  p = _ALIGN(p, sz >= 8 ? 8 : 4);

            nstr = find_flat_dt_string(noff);
            if (nstr == NULL) {
                  printk(KERN_WARNING "Can't find property index"
                        " name !\n");
                  return NULL;
            }
            if (strcmp(name, nstr) == 0) {
                  if (size)
                        *size = sz;
                  return (void *)p;
            }
            p += sz;
            p = _ALIGN(p, 4);
      } while (1);
}

int __init of_flat_dt_is_compatible(unsigned long node, const char *compat)
{
      const char *cp;
      unsigned long cplen, l;

      cp = of_get_flat_dt_prop(node, "compatible", &cplen);
      if (cp == NULL)
            return 0;
      while (cplen > 0) {
            if (strncasecmp(cp, compat, strlen(compat)) == 0)
                  return 1;
            l = strlen(cp) + 1;
            cp += l;
            cplen -= l;
      }

      return 0;
}

static void *__init unflatten_dt_alloc(unsigned long *mem, unsigned long size,
                              unsigned long align)
{
      void *res;

      *mem = _ALIGN(*mem, align);
      res = (void *)*mem;
      *mem += size;

      return res;
}

static unsigned long __init unflatten_dt_node(unsigned long mem,
                              unsigned long *p,
                              struct device_node *dad,
                              struct device_node ***allnextpp,
                              unsigned long fpsize)
{
      struct device_node *np;
      struct property *pp, **prev_pp = NULL;
      char *pathp;
      u32 tag;
      unsigned int l, allocl;
      int has_name = 0;
      int new_format = 0;

      tag = *((u32 *)(*p));
      if (tag != OF_DT_BEGIN_NODE) {
            printk("Weird tag at start of node: %x\n", tag);
            return mem;
      }
      *p += 4;
      pathp = (char *)*p;
      l = allocl = strlen(pathp) + 1;
      *p = _ALIGN(*p + l, 4);

      /* version 0x10 has a more compact unit name here instead of the full
       * path. we accumulate the full path size using "fpsize", we'll rebuild
       * it later. We detect this because the first character of the name is
       * not '/'.
       */
      if ((*pathp) != '/') {
            new_format = 1;
            if (fpsize == 0) {
                  /* root node: special case. fpsize accounts for path
                   * plus terminating zero. root node only has '/', so
                   * fpsize should be 2, but we want to avoid the first
                   * level nodes to have two '/' so we use fpsize 1 here
                   */
                  fpsize = 1;
                  allocl = 2;
            } else {
                  /* account for '/' and path size minus terminal 0
                   * already in 'l'
                   */
                  fpsize += l;
                  allocl = fpsize;
            }
      }

      np = unflatten_dt_alloc(&mem, sizeof(struct device_node) + allocl,
                        __alignof__(struct device_node));
      if (allnextpp) {
            memset(np, 0, sizeof(*np));
            np->full_name = ((char *)np) + sizeof(struct device_node);
            if (new_format) {
                  char *p2 = np->full_name;
                  /* rebuild full path for new format */
                  if (dad && dad->parent) {
                        strcpy(p2, dad->full_name);
#ifdef DEBUG
                        if ((strlen(p2) + l + 1) != allocl) {
                              pr_debug("%s: p: %d, l: %d, a: %d\n",
                                    pathp, (int)strlen(p2),
                                    l, allocl);
                        }
#endif
                        p2 += strlen(p2);
                  }
                  *(p2++) = '/';
                  memcpy(p2, pathp, l);
            } else
                  memcpy(np->full_name, pathp, l);
            prev_pp = &np->properties;
            **allnextpp = np;
            *allnextpp = &np->allnext;
            if (dad != NULL) {
                  np->parent = dad;
                  /* we temporarily use the next field as `last_child'*/
                  if (dad->next == NULL)
                        dad->child = np;
                  else
                        dad->next->sibling = np;
                  dad->next = np;
            }
            kref_init(&np->kref);
      }
      while (1) {
            u32 sz, noff;
            char *pname;

            tag = *((u32 *)(*p));
            if (tag == OF_DT_NOP) {
                  *p += 4;
                  continue;
            }
            if (tag != OF_DT_PROP)
                  break;
            *p += 4;
            sz = *((u32 *)(*p));
            noff = *((u32 *)((*p) + 4));
            *p += 8;
            if (initial_boot_params->version < 0x10)
                  *p = _ALIGN(*p, sz >= 8 ? 8 : 4);

            pname = find_flat_dt_string(noff);
            if (pname == NULL) {
                  printk(KERN_INFO
                        "Can't find property name in list !\n");
                  break;
            }
            if (strcmp(pname, "name") == 0)
                  has_name = 1;
            l = strlen(pname) + 1;
            pp = unflatten_dt_alloc(&mem, sizeof(struct property),
                              __alignof__(struct property));
            if (allnextpp) {
                  if (strcmp(pname, "linux,phandle") == 0) {
                        np->node = *((u32 *)*p);
                        if (np->linux_phandle == 0)
                              np->linux_phandle = np->node;
                  }
                  if (strcmp(pname, "ibm,phandle") == 0)
                        np->linux_phandle = *((u32 *)*p);
                  pp->name = pname;
                  pp->length = sz;
                  pp->value = (void *)*p;
                  *prev_pp = pp;
                  prev_pp = &pp->next;
            }
            *p = _ALIGN((*p) + sz, 4);
      }
      /* with version 0x10 we may not have the name property, recreate
       * it here from the unit name if absent
       */
      if (!has_name) {
            char *p1 = pathp, *ps = pathp, *pa = NULL;
            int sz;

            while (*p1) {
                  if ((*p1) == '@')
                        pa = p1;
                  if ((*p1) == '/')
                        ps = p1 + 1;
                  p1++;
            }
            if (pa < ps)
                  pa = p1;
            sz = (pa - ps) + 1;
            pp = unflatten_dt_alloc(&mem, sizeof(struct property) + sz,
                              __alignof__(struct property));
            if (allnextpp) {
                  pp->name = "name";
                  pp->length = sz;
                  pp->value = pp + 1;
                  *prev_pp = pp;
                  prev_pp = &pp->next;
                  memcpy(pp->value, ps, sz - 1);
                  ((char *)pp->value)[sz - 1] = 0;
                  pr_debug("fixed up name for %s -> %s\n", pathp,
                        (char *)pp->value);
            }
      }
      if (allnextpp) {
            *prev_pp = NULL;
            np->name = of_get_property(np, "name", NULL);
            np->type = of_get_property(np, "device_type", NULL);

            if (!np->name)
                  np->name = "<NULL>";
            if (!np->type)
                  np->type = "<NULL>";
      }
      while (tag == OF_DT_BEGIN_NODE) {
            mem = unflatten_dt_node(mem, p, np, allnextpp, fpsize);
            tag = *((u32 *)(*p));
      }
      if (tag != OF_DT_END_NODE) {
            printk(KERN_INFO "Weird tag at end of node: %x\n", tag);
            return mem;
      }
      *p += 4;
      return mem;
}

/**
 * unflattens the device-tree passed by the firmware, creating the
 * tree of struct device_node. It also fills the "name" and "type"
 * pointers of the nodes so the normal device-tree walking functions
 * can be used (this used to be done by finish_device_tree)
 */
void __init unflatten_device_tree(void)
{
      unsigned long start, mem, size;
      struct device_node **allnextp = &allnodes;

      pr_debug(" -> unflatten_device_tree()\n");

      /* First pass, scan for size */
      start = ((unsigned long)initial_boot_params) +
            initial_boot_params->off_dt_struct;
      size = unflatten_dt_node(0, &start, NULL, NULL, 0);
      size = (size | 3) + 1;

      pr_debug("  size is %lx, allocating...\n", size);

      /* Allocate memory for the expanded device tree */
      mem = lmb_alloc(size + 4, __alignof__(struct device_node));
      mem = (unsigned long) __va(mem);

      ((u32 *)mem)[size / 4] = 0xdeadbeef;

      pr_debug("  unflattening %lx...\n", mem);

      /* Second pass, do actual unflattening */
      start = ((unsigned long)initial_boot_params) +
            initial_boot_params->off_dt_struct;
      unflatten_dt_node(mem, &start, NULL, &allnextp, 0);
      if (*((u32 *)start) != OF_DT_END)
            printk(KERN_WARNING "Weird tag at end of tree: %08x\n",
                  *((u32 *)start));
      if (((u32 *)mem)[size / 4] != 0xdeadbeef)
            printk(KERN_WARNING "End of tree marker overwritten: %08x\n",
                  ((u32 *)mem)[size / 4]);
      *allnextp = NULL;

      /* Get pointer to OF "/chosen" node for use everywhere */
      of_chosen = of_find_node_by_path("/chosen");
      if (of_chosen == NULL)
            of_chosen = of_find_node_by_path("/chosen@0");

      pr_debug(" <- unflatten_device_tree()\n");
}

#define early_init_dt_scan_drconf_memory(node) 0

static int __init early_init_dt_scan_cpus(unsigned long node,
                                const char *uname, int depth,
                                void *data)
{
      static int logical_cpuid;
      char *type = of_get_flat_dt_prop(node, "device_type", NULL);
      const u32 *intserv;
      int i, nthreads;
      int found = 0;

      /* We are scanning "cpu" nodes only */
      if (type == NULL || strcmp(type, "cpu") != 0)
            return 0;

      /* Get physical cpuid */
      intserv = of_get_flat_dt_prop(node, "reg", NULL);
      nthreads = 1;

      /*
       * Now see if any of these threads match our boot cpu.
       * NOTE: This must match the parsing done in smp_setup_cpu_maps.
       */
      for (i = 0; i < nthreads; i++) {
            /*
             * version 2 of the kexec param format adds the phys cpuid of
             * booted proc.
             */
            if (initial_boot_params && initial_boot_params->version >= 2) {
                  if (intserv[i] ==
                              initial_boot_params->boot_cpuid_phys) {
                        found = 1;
                        break;
                  }
            } else {
                  /*
                   * Check if it's the boot-cpu, set it's hw index now,
                   * unfortunately this format did not support booting
                   * off secondary threads.
                   */
                  if (of_get_flat_dt_prop(node,
                              "linux,boot-cpu", NULL) != NULL) {
                        found = 1;
                        break;
                  }
            }

#ifdef CONFIG_SMP
            /* logical cpu id is always 0 on UP kernels */
            logical_cpuid++;
#endif
      }

      if (found) {
            pr_debug("boot cpu: logical %d physical %d\n", logical_cpuid,
                  intserv[i]);
            boot_cpuid = logical_cpuid;
      }

      return 0;
}

#ifdef CONFIG_BLK_DEV_INITRD
static void __init early_init_dt_check_for_initrd(unsigned long node)
{
      unsigned long l;
      u32 *prop;

      pr_debug("Looking for initrd properties... ");

      prop = of_get_flat_dt_prop(node, "linux,initrd-start", &l);
      if (prop) {
            initrd_start = (unsigned long)
                              __va((u32)of_read_ulong(prop, l/4));

            prop = of_get_flat_dt_prop(node, "linux,initrd-end", &l);
            if (prop) {
                  initrd_end = (unsigned long)
                              __va((u32)of_read_ulong(prop, 1/4));
                  initrd_below_start_ok = 1;
            } else {
                  initrd_start = 0;
            }
      }

      pr_debug("initrd_start=0x%lx  initrd_end=0x%lx\n",
                              initrd_start, initrd_end);
}
#else
static inline void early_init_dt_check_for_initrd(unsigned long node)
{
}
#endif /* CONFIG_BLK_DEV_INITRD */

static int __init early_init_dt_scan_chosen(unsigned long node,
                        const char *uname, int depth, void *data)
{
      unsigned long l;
      char *p;

      pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);

      if (depth != 1 ||
            (strcmp(uname, "chosen") != 0 &&
                        strcmp(uname, "chosen@0") != 0))
            return 0;

#ifdef CONFIG_KEXEC
      lprop = (u64 *)of_get_flat_dt_prop(node,
                        "linux,crashkernel-base", NULL);
      if (lprop)
            crashk_res.start = *lprop;

      lprop = (u64 *)of_get_flat_dt_prop(node,
                        "linux,crashkernel-size", NULL);
      if (lprop)
            crashk_res.end = crashk_res.start + *lprop - 1;
#endif

      early_init_dt_check_for_initrd(node);

      /* Retreive command line */
      p = of_get_flat_dt_prop(node, "bootargs", &l);
      if (p != NULL && l > 0)
            strlcpy(cmd_line, p, min((int)l, COMMAND_LINE_SIZE));

#ifdef CONFIG_CMDLINE
#ifndef CONFIG_CMDLINE_FORCE
      if (p == NULL || l == 0 || (l == 1 && (*p) == 0))
#endif
            strlcpy(cmd_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#endif /* CONFIG_CMDLINE */

      pr_debug("Command line is: %s\n", cmd_line);

      /* break now */
      return 1;
}

static int __init early_init_dt_scan_root(unsigned long node,
                        const char *uname, int depth, void *data)
{
      u32 *prop;

      if (depth != 0)
            return 0;

      prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
      dt_root_size_cells = (prop == NULL) ? 1 : *prop;
      pr_debug("dt_root_size_cells = %x\n", dt_root_size_cells);

      prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
      dt_root_addr_cells = (prop == NULL) ? 2 : *prop;
      pr_debug("dt_root_addr_cells = %x\n", dt_root_addr_cells);

      /* break now */
      return 1;
}

static u64 __init dt_mem_next_cell(int s, cell_t **cellp)
{
      cell_t *p = *cellp;

      *cellp = p + s;
      return of_read_number(p, s);
}

static int __init early_init_dt_scan_memory(unsigned long node,
                        const char *uname, int depth, void *data)
{
      char *type = of_get_flat_dt_prop(node, "device_type", NULL);
      cell_t *reg, *endp;
      unsigned long l;

      /* Look for the ibm,dynamic-reconfiguration-memory node */
/*    if (depth == 1 &&
            strcmp(uname, "ibm,dynamic-reconfiguration-memory") == 0)
            return early_init_dt_scan_drconf_memory(node);
*/
      /* We are scanning "memory" nodes only */
      if (type == NULL) {
            /*
             * The longtrail doesn't have a device_type on the
             * /memory node, so look for the node called /memory@0.
             */
            if (depth != 1 || strcmp(uname, "memory@0") != 0)
                  return 0;
      } else if (strcmp(type, "memory") != 0)
            return 0;

      reg = (cell_t *)of_get_flat_dt_prop(node, "linux,usable-memory", &l);
      if (reg == NULL)
            reg = (cell_t *)of_get_flat_dt_prop(node, "reg", &l);
      if (reg == NULL)
            return 0;

      endp = reg + (l / sizeof(cell_t));

      pr_debug("memory scan node %s, reg size %ld, data: %x %x %x %x,\n",
            uname, l, reg[0], reg[1], reg[2], reg[3]);

      while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
            u64 base, size;

            base = dt_mem_next_cell(dt_root_addr_cells, &reg);
            size = dt_mem_next_cell(dt_root_size_cells, &reg);

            if (size == 0)
                  continue;
            pr_debug(" - %llx ,  %llx\n", (unsigned long long)base,
                  (unsigned long long)size);

            lmb_add(base, size);
      }
      return 0;
}

#ifdef CONFIG_PHYP_DUMP
/**
 * phyp_dump_calculate_reserve_size() - reserve variable boot area 5% or arg
 *
 * Function to find the largest size we need to reserve
 * during early boot process.
 *
 * It either looks for boot param and returns that OR
 * returns larger of 256 or 5% rounded down to multiples of 256MB.
 *
 */
static inline unsigned long phyp_dump_calculate_reserve_size(void)
{
      unsigned long tmp;

      if (phyp_dump_info->reserve_bootvar)
            return phyp_dump_info->reserve_bootvar;

      /* divide by 20 to get 5% of value */
      tmp = lmb_end_of_DRAM();
      do_div(tmp, 20);

      /* round it down in multiples of 256 */
      tmp = tmp & ~0x0FFFFFFFUL;

      return (tmp > PHYP_DUMP_RMR_END ? tmp : PHYP_DUMP_RMR_END);
}

/**
 * phyp_dump_reserve_mem() - reserve all not-yet-dumped mmemory
 *
 * This routine may reserve memory regions in the kernel only
 * if the system is supported and a dump was taken in last
 * boot instance or if the hardware is supported and the
 * scratch area needs to be setup. In other instances it returns
 * without reserving anything. The memory in case of dump being
 * active is freed when the dump is collected (by userland tools).
 */
static void __init phyp_dump_reserve_mem(void)
{
      unsigned long base, size;
      unsigned long variable_reserve_size;

      if (!phyp_dump_info->phyp_dump_configured) {
            printk(KERN_ERR "Phyp-dump not supported on this hardware\n");
            return;
      }

      if (!phyp_dump_info->phyp_dump_at_boot) {
            printk(KERN_INFO "Phyp-dump disabled at boot time\n");
            return;
      }

      variable_reserve_size = phyp_dump_calculate_reserve_size();

      if (phyp_dump_info->phyp_dump_is_active) {
            /* Reserve *everything* above RMR.Area freed by userland tools*/
            base = variable_reserve_size;
            size = lmb_end_of_DRAM() - base;

            /* XXX crashed_ram_end is wrong, since it may be beyond
             * the memory_limit, it will need to be adjusted. */
            lmb_reserve(base, size);

            phyp_dump_info->init_reserve_start = base;
            phyp_dump_info->init_reserve_size = size;
      } else {
            size = phyp_dump_info->cpu_state_size +
                  phyp_dump_info->hpte_region_size +
                  variable_reserve_size;
            base = lmb_end_of_DRAM() - size;
            lmb_reserve(base, size);
            phyp_dump_info->init_reserve_start = base;
            phyp_dump_info->init_reserve_size = size;
      }
}
#else
static inline void __init phyp_dump_reserve_mem(void) {}
#endif /* CONFIG_PHYP_DUMP  && CONFIG_PPC_RTAS */

#ifdef CONFIG_EARLY_PRINTK
/* MS this is Microblaze specifig function */
static int __init early_init_dt_scan_serial(unsigned long node,
                        const char *uname, int depth, void *data)
{
      unsigned long l;
      char *p;
      int *addr;

      pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);

/* find all serial nodes */
      if (strncmp(uname, "serial", 6) != 0)
            return 0;

      early_init_dt_check_for_initrd(node);

/* find compatible node with uartlite */
      p = of_get_flat_dt_prop(node, "compatible", &l);
      if ((strncmp(p, "xlnx,xps-uartlite", 17) != 0) &&
                  (strncmp(p, "xlnx,opb-uartlite", 17) != 0))
            return 0;

      addr = of_get_flat_dt_prop(node, "reg", &l);
      return *addr; /* return address */
}

/* this function is looking for early uartlite console - Microblaze specific */
int __init early_uartlite_console(void)
{
      return of_scan_flat_dt(early_init_dt_scan_serial, NULL);
}
#endif

void __init early_init_devtree(void *params)
{
      pr_debug(" -> early_init_devtree(%p)\n", params);

      /* Setup flat device-tree pointer */
      initial_boot_params = params;

#ifdef CONFIG_PHYP_DUMP
      /* scan tree to see if dump occured during last boot */
      of_scan_flat_dt(early_init_dt_scan_phyp_dump, NULL);
#endif

      /* Retrieve various informations from the /chosen node of the
       * device-tree, including the platform type, initrd location and
       * size, TCE reserve, and more ...
       */
      of_scan_flat_dt(early_init_dt_scan_chosen, NULL);

      /* Scan memory nodes and rebuild LMBs */
      lmb_init();
      of_scan_flat_dt(early_init_dt_scan_root, NULL);
      of_scan_flat_dt(early_init_dt_scan_memory, NULL);

      /* Save command line for /proc/cmdline and then parse parameters */
      strlcpy(boot_command_line, cmd_line, COMMAND_LINE_SIZE);
      parse_early_param();

      lmb_analyze();

      pr_debug("Phys. mem: %lx\n", (unsigned long) lmb_phys_mem_size());

      pr_debug("Scanning CPUs ...\n");

      /* Retreive CPU related informations from the flat tree
       * (altivec support, boot CPU ID, ...)
       */
      of_scan_flat_dt(early_init_dt_scan_cpus, NULL);

      pr_debug(" <- early_init_devtree()\n");
}

/**
 * Indicates whether the root node has a given value in its
 * compatible property.
 */
int machine_is_compatible(const char *compat)
{
      struct device_node *root;
      int rc = 0;

      root = of_find_node_by_path("/");
      if (root) {
            rc = of_device_is_compatible(root, compat);
            of_node_put(root);
      }
      return rc;
}
EXPORT_SYMBOL(machine_is_compatible);

/*******
 *
 * New implementation of the OF "find" APIs, return a refcounted
 * object, call of_node_put() when done.  The device tree and list
 * are protected by a rw_lock.
 *
 * Note that property management will need some locking as well,
 * this isn't dealt with yet.
 *
 *******/

/**
 *    of_find_node_by_phandle - Find a node given a phandle
 *    @handle:    phandle of the node to find
 *
 *    Returns a node pointer with refcount incremented, use
 *    of_node_put() on it when done.
 */
struct device_node *of_find_node_by_phandle(phandle handle)
{
      struct device_node *np;

      read_lock(&devtree_lock);
      for (np = allnodes; np != NULL; np = np->allnext)
            if (np->linux_phandle == handle)
                  break;
      of_node_get(np);
      read_unlock(&devtree_lock);
      return np;
}
EXPORT_SYMBOL(of_find_node_by_phandle);

/**
 *    of_find_all_nodes - Get next node in global list
 *    @prev:      Previous node or NULL to start iteration
 *          of_node_put() will be called on it
 *
 *    Returns a node pointer with refcount incremented, use
 *    of_node_put() on it when done.
 */
struct device_node *of_find_all_nodes(struct device_node *prev)
{
      struct device_node *np;

      read_lock(&devtree_lock);
      np = prev ? prev->allnext : allnodes;
      for (; np != NULL; np = np->allnext)
            if (of_node_get(np))
                  break;
      of_node_put(prev);
      read_unlock(&devtree_lock);
      return np;
}
EXPORT_SYMBOL(of_find_all_nodes);

/**
 *    of_node_get - Increment refcount of a node
 *    @node:      Node to inc refcount, NULL is supported to
 *          simplify writing of callers
 *
 *    Returns node.
 */
struct device_node *of_node_get(struct device_node *node)
{
      if (node)
            kref_get(&node->kref);
      return node;
}
EXPORT_SYMBOL(of_node_get);

static inline struct device_node *kref_to_device_node(struct kref *kref)
{
      return container_of(kref, struct device_node, kref);
}

/**
 *    of_node_release - release a dynamically allocated node
 *    @kref:  kref element of the node to be released
 *
 *    In of_node_put() this function is passed to kref_put()
 *    as the destructor.
 */
static void of_node_release(struct kref *kref)
{
      struct device_node *node = kref_to_device_node(kref);
      struct property *prop = node->properties;

      /* We should never be releasing nodes that haven't been detached. */
      if (!of_node_check_flag(node, OF_DETACHED)) {
            printk(KERN_INFO "WARNING: Bad of_node_put() on %s\n",
                  node->full_name);
            dump_stack();
            kref_init(&node->kref);
            return;
      }

      if (!of_node_check_flag(node, OF_DYNAMIC))
            return;

      while (prop) {
            struct property *next = prop->next;
            kfree(prop->name);
            kfree(prop->value);
            kfree(prop);
            prop = next;

            if (!prop) {
                  prop = node->deadprops;
                  node->deadprops = NULL;
            }
      }
      kfree(node->full_name);
      kfree(node->data);
      kfree(node);
}

/**
 *    of_node_put - Decrement refcount of a node
 *    @node:      Node to dec refcount, NULL is supported to
 *          simplify writing of callers
 *
 */
void of_node_put(struct device_node *node)
{
      if (node)
            kref_put(&node->kref, of_node_release);
}
EXPORT_SYMBOL(of_node_put);

/*
 * Plug a device node into the tree and global list.
 */
void of_attach_node(struct device_node *np)
{
      unsigned long flags;

      write_lock_irqsave(&devtree_lock, flags);
      np->sibling = np->parent->child;
      np->allnext = allnodes;
      np->parent->child = np;
      allnodes = np;
      write_unlock_irqrestore(&devtree_lock, flags);
}

/*
 * "Unplug" a node from the device tree.  The caller must hold
 * a reference to the node.  The memory associated with the node
 * is not freed until its refcount goes to zero.
 */
void of_detach_node(struct device_node *np)
{
      struct device_node *parent;
      unsigned long flags;

      write_lock_irqsave(&devtree_lock, flags);

      parent = np->parent;
      if (!parent)
            goto out_unlock;

      if (allnodes == np)
            allnodes = np->allnext;
      else {
            struct device_node *prev;
            for (prev = allnodes;
                 prev->allnext != np;
                 prev = prev->allnext)
                  ;
            prev->allnext = np->allnext;
      }

      if (parent->child == np)
            parent->child = np->sibling;
      else {
            struct device_node *prevsib;
            for (prevsib = np->parent->child;
                 prevsib->sibling != np;
                 prevsib = prevsib->sibling)
                  ;
            prevsib->sibling = np->sibling;
      }

      of_node_set_flag(np, OF_DETACHED);

out_unlock:
      write_unlock_irqrestore(&devtree_lock, flags);
}

/*
 * Add a property to a node
 */
int prom_add_property(struct device_node *np, struct property *prop)
{
      struct property **next;
      unsigned long flags;

      prop->next = NULL;
      write_lock_irqsave(&devtree_lock, flags);
      next = &np->properties;
      while (*next) {
            if (strcmp(prop->name, (*next)->name) == 0) {
                  /* duplicate ! don't insert it */
                  write_unlock_irqrestore(&devtree_lock, flags);
                  return -1;
            }
            next = &(*next)->next;
      }
      *next = prop;
      write_unlock_irqrestore(&devtree_lock, flags);

#ifdef CONFIG_PROC_DEVICETREE
      /* try to add to proc as well if it was initialized */
      if (np->pde)
            proc_device_tree_add_prop(np->pde, prop);
#endif /* CONFIG_PROC_DEVICETREE */

      return 0;
}

/*
 * Remove a property from a node.  Note that we don't actually
 * remove it, since we have given out who-knows-how-many pointers
 * to the data using get-property.  Instead we just move the property
 * to the "dead properties" list, so it won't be found any more.
 */
int prom_remove_property(struct device_node *np, struct property *prop)
{
      struct property **next;
      unsigned long flags;
      int found = 0;

      write_lock_irqsave(&devtree_lock, flags);
      next = &np->properties;
      while (*next) {
            if (*next == prop) {
                  /* found the node */
                  *next = prop->next;
                  prop->next = np->deadprops;
                  np->deadprops = prop;
                  found = 1;
                  break;
            }
            next = &(*next)->next;
      }
      write_unlock_irqrestore(&devtree_lock, flags);

      if (!found)
            return -ENODEV;

#ifdef CONFIG_PROC_DEVICETREE
      /* try to remove the proc node as well */
      if (np->pde)
            proc_device_tree_remove_prop(np->pde, prop);
#endif /* CONFIG_PROC_DEVICETREE */

      return 0;
}

/*
 * Update a property in a node.  Note that we don't actually
 * remove it, since we have given out who-knows-how-many pointers
 * to the data using get-property.  Instead we just move the property
 * to the "dead properties" list, and add the new property to the
 * property list
 */
int prom_update_property(struct device_node *np,
                   struct property *newprop,
                   struct property *oldprop)
{
      struct property **next;
      unsigned long flags;
      int found = 0;

      write_lock_irqsave(&devtree_lock, flags);
      next = &np->properties;
      while (*next) {
            if (*next == oldprop) {
                  /* found the node */
                  newprop->next = oldprop->next;
                  *next = newprop;
                  oldprop->next = np->deadprops;
                  np->deadprops = oldprop;
                  found = 1;
                  break;
            }
            next = &(*next)->next;
      }
      write_unlock_irqrestore(&devtree_lock, flags);

      if (!found)
            return -ENODEV;

#ifdef CONFIG_PROC_DEVICETREE
      /* try to add to proc as well if it was initialized */
      if (np->pde)
            proc_device_tree_update_prop(np->pde, newprop, oldprop);
#endif /* CONFIG_PROC_DEVICETREE */

      return 0;
}

#if defined(CONFIG_DEBUG_FS) && defined(DEBUG)
static struct debugfs_blob_wrapper flat_dt_blob;

static int __init export_flat_device_tree(void)
{
      struct dentry *d;

      flat_dt_blob.data = initial_boot_params;
      flat_dt_blob.size = initial_boot_params->totalsize;

      d = debugfs_create_blob("flat-device-tree", S_IFREG | S_IRUSR,
                        of_debugfs_root, &flat_dt_blob);
      if (!d)
            return 1;

      return 0;
}
device_initcall(export_flat_device_tree);
#endif

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