PM / sleep: Asynchronous threads for suspend_noirq

[linux/fpc-iii.git] / drivers / of / fdt.c

/*
 * Functions for working with the Flattened Device Tree data format
 *
 * Copyright 2009 Benjamin Herrenschmidt, IBM Corp
 * benh@kernel.crashing.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/initrd.h>
#include <linux/memblock.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>

#include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
#ifdef CONFIG_PPC
#include <asm/machdep.h>
#endif /* CONFIG_PPC */

#include <asm/page.h>

char *of_fdt_get_string(struct boot_param_header *blob, u32 offset)
{
        return ((char *)blob) +
                be32_to_cpu(blob->off_dt_strings) + offset;
}

/**
 * of_fdt_get_property - Given a node in the given flat blob, return
 * the property ptr
 */
void *of_fdt_get_property(struct boot_param_header *blob,
                       unsigned long node, const char *name,
                       unsigned long *size)
{
        unsigned long p = node;

        do {
                u32 tag = be32_to_cpup((__be32 *)p);
                u32 sz, noff;
                const char *nstr;

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

                sz = be32_to_cpup((__be32 *)p);
                noff = be32_to_cpup((__be32 *)(p + 4));
                p += 8;
                if (be32_to_cpu(blob->version) < 0x10)
                        p = ALIGN(p, sz >= 8 ? 8 : 4);

                nstr = of_fdt_get_string(blob, noff);
                if (nstr == NULL) {
                        pr_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);
}

/**
 * of_fdt_is_compatible - Return true if given node from the given blob has
 * compat in its compatible list
 * @blob: A device tree blob
 * @node: node to test
 * @compat: compatible string to compare with compatible list.
 *
 * On match, returns a non-zero value with smaller values returned for more
 * specific compatible values.
 */
int of_fdt_is_compatible(struct boot_param_header *blob,
                      unsigned long node, const char *compat)
{
        const char *cp;
        unsigned long cplen, l, score = 0;

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

        return 0;
}

/**
 * of_fdt_match - Return true if node matches a list of compatible values
 */
int of_fdt_match(struct boot_param_header *blob, unsigned long node,
                 const char *const *compat)
{
        unsigned int tmp, score = 0;

        if (!compat)
                return 0;

        while (*compat) {
                tmp = of_fdt_is_compatible(blob, node, *compat);
                if (tmp && (score == 0 || (tmp < score)))
                        score = tmp;
                compat++;
        }

        return score;
}

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

        *mem = PTR_ALIGN(*mem, align);
        res = *mem;
        *mem += size;

        return res;
}

/**
 * unflatten_dt_node - Alloc and populate a device_node from the flat tree
 * @blob: The parent device tree blob
 * @mem: Memory chunk to use for allocating device nodes and properties
 * @p: pointer to node in flat tree
 * @dad: Parent struct device_node
 * @allnextpp: pointer to ->allnext from last allocated device_node
 * @fpsize: Size of the node path up at the current depth.
 */
static void * unflatten_dt_node(struct boot_param_header *blob,
                                void *mem,
                                void **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 = be32_to_cpup(*p);
        if (tag != OF_DT_BEGIN_NODE) {
                pr_err("Weird tag at start of node: %x\n", tag);
                return mem;
        }
        *p += 4;
        pathp = *p;
        l = allocl = strlen(pathp) + 1;
        *p = PTR_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;
                        l = 1;
                        *pathp = '\0';
                } 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) {
                char *fn;
                np->full_name = fn = ((char *)np) + sizeof(*np);
                if (new_format) {
                        /* rebuild full path for new format */
                        if (dad && dad->parent) {
                                strcpy(fn, dad->full_name);
#ifdef DEBUG
                                if ((strlen(fn) + l + 1) != allocl) {
                                        pr_debug("%s: p: %d, l: %d, a: %d\n",
                                                pathp, (int)strlen(fn),
                                                l, allocl);
                                }
#endif
                                fn += strlen(fn);
                        }
                        *(fn++) = '/';
                }
                memcpy(fn, 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);
        }
        /* process properties */
        while (1) {
                u32 sz, noff;
                char *pname;

                tag = be32_to_cpup(*p);
                if (tag == OF_DT_NOP) {
                        *p += 4;
                        continue;
                }
                if (tag != OF_DT_PROP)
                        break;
                *p += 4;
                sz = be32_to_cpup(*p);
                noff = be32_to_cpup(*p + 4);
                *p += 8;
                if (be32_to_cpu(blob->version) < 0x10)
                        *p = PTR_ALIGN(*p, sz >= 8 ? 8 : 4);

                pname = of_fdt_get_string(blob, noff);
                if (pname == NULL) {
                        pr_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) {
                        /* We accept flattened tree phandles either in
                         * ePAPR-style "phandle" properties, or the
                         * legacy "linux,phandle" properties.  If both
                         * appear and have different values, things
                         * will get weird.  Don't do that. */
                        if ((strcmp(pname, "phandle") == 0) ||
                            (strcmp(pname, "linux,phandle") == 0)) {
                                if (np->phandle == 0)
                                        np->phandle = be32_to_cpup((__be32*)*p);
                        }
                        /* And we process the "ibm,phandle" property
                         * used in pSeries dynamic device tree
                         * stuff */
                        if (strcmp(pname, "ibm,phandle") == 0)
                                np->phandle = be32_to_cpup((__be32 *)*p);
                        pp->name = pname;
                        pp->length = sz;
                        pp->value = *p;
                        *prev_pp = pp;
                        prev_pp = &pp->next;
                }
                *p = PTR_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 || tag == OF_DT_NOP) {
                if (tag == OF_DT_NOP)
                        *p += 4;
                else
                        mem = unflatten_dt_node(blob, mem, p, np, allnextpp,
                                                fpsize);
                tag = be32_to_cpup(*p);
        }
        if (tag != OF_DT_END_NODE) {
                pr_err("Weird tag at end of node: %x\n", tag);
                return mem;
        }
        *p += 4;
        return mem;
}

/**
 * __unflatten_device_tree - create tree of device_nodes from flat blob
 *
 * unflattens a device-tree, 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.
 * @blob: The blob to expand
 * @mynodes: The device_node tree created by the call
 * @dt_alloc: An allocator that provides a virtual address to memory
 * for the resulting tree
 */
static void __unflatten_device_tree(struct boot_param_header *blob,
                             struct device_node **mynodes,
                             void * (*dt_alloc)(u64 size, u64 align))
{
        unsigned long size;
        void *start, *mem;
        struct device_node **allnextp = mynodes;

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

        if (!blob) {
                pr_debug("No device tree pointer\n");
                return;
        }

        pr_debug("Unflattening device tree:\n");
        pr_debug("magic: %08x\n", be32_to_cpu(blob->magic));
        pr_debug("size: %08x\n", be32_to_cpu(blob->totalsize));
        pr_debug("version: %08x\n", be32_to_cpu(blob->version));

        if (be32_to_cpu(blob->magic) != OF_DT_HEADER) {
                pr_err("Invalid device tree blob header\n");
                return;
        }

        /* First pass, scan for size */
        start = ((void *)blob) + be32_to_cpu(blob->off_dt_struct);
        size = (unsigned long)unflatten_dt_node(blob, 0, &start, NULL, NULL, 0);
        size = ALIGN(size, 4);

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

        /* Allocate memory for the expanded device tree */
        mem = dt_alloc(size + 4, __alignof__(struct device_node));
        memset(mem, 0, size);

        *(__be32 *)(mem + size) = cpu_to_be32(0xdeadbeef);

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

        /* Second pass, do actual unflattening */
        start = ((void *)blob) + be32_to_cpu(blob->off_dt_struct);
        unflatten_dt_node(blob, mem, &start, NULL, &allnextp, 0);
        if (be32_to_cpup(start) != OF_DT_END)
                pr_warning("Weird tag at end of tree: %08x\n", be32_to_cpup(start));
        if (be32_to_cpup(mem + size) != 0xdeadbeef)
                pr_warning("End of tree marker overwritten: %08x\n",
                           be32_to_cpup(mem + size));
        *allnextp = NULL;

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

static void *kernel_tree_alloc(u64 size, u64 align)
{
        return kzalloc(size, GFP_KERNEL);
}

/**
 * of_fdt_unflatten_tree - create tree of device_nodes from flat blob
 *
 * 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.
 */
void of_fdt_unflatten_tree(unsigned long *blob,
                        struct device_node **mynodes)
{
        struct boot_param_header *device_tree =
                (struct boot_param_header *)blob;
        __unflatten_device_tree(device_tree, mynodes, &kernel_tree_alloc);
}
EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);

/* Everything below here references initial_boot_params directly. */
int __initdata dt_root_addr_cells;
int __initdata dt_root_size_cells;

struct boot_param_header *initial_boot_params;

#ifdef CONFIG_OF_EARLY_FLATTREE

/**
 * of_scan_flat_dt - scan flattened tree blob and call callback on each.
 * @it: callback function
 * @data: context data pointer
 *
 * This function is used to scan the flattened device-tree, it is
 * used to extract the memory information 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) +
                be32_to_cpu(initial_boot_params->off_dt_struct);
        int rc = 0;
        int depth = -1;

        do {
                u32 tag = be32_to_cpup((__be32 *)p);
                const 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 = be32_to_cpup((__be32 *)p);
                        p += 8;
                        if (be32_to_cpu(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) {
                        pr_err("Invalid tag %x in flat device tree!\n", tag);
                        return -EINVAL;
                }
                depth++;
                pathp = (char *)p;
                p = ALIGN(p + strlen(pathp) + 1, 4);
                if (*pathp == '/')
                        pathp = kbasename(pathp);
                rc = it(p, pathp, depth, data);
                if (rc != 0)
                        break;
        } while (1);

        return rc;
}

/**
 * of_get_flat_dt_root - find the root node in the flat blob
 */
unsigned long __init of_get_flat_dt_root(void)
{
        unsigned long p = ((unsigned long)initial_boot_params) +
                be32_to_cpu(initial_boot_params->off_dt_struct);

        while (be32_to_cpup((__be32 *)p) == OF_DT_NOP)
                p += 4;
        BUG_ON(be32_to_cpup((__be32 *)p) != OF_DT_BEGIN_NODE);
        p += 4;
        return ALIGN(p + strlen((char *)p) + 1, 4);
}

/**
 * of_get_flat_dt_prop - Given a node in the flat blob, return the property ptr
 *
 * 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)
{
        return of_fdt_get_property(initial_boot_params, node, name, size);
}

/**
 * of_flat_dt_is_compatible - Return true if given node has compat in compatible list
 * @node: node to test
 * @compat: compatible string to compare with compatible list.
 */
int __init of_flat_dt_is_compatible(unsigned long node, const char *compat)
{
        return of_fdt_is_compatible(initial_boot_params, node, compat);
}

/**
 * of_flat_dt_match - Return true if node matches a list of compatible values
 */
int __init of_flat_dt_match(unsigned long node, const char *const *compat)
{
        return of_fdt_match(initial_boot_params, node, compat);
}

struct fdt_scan_status {
        const char *name;
        int namelen;
        int depth;
        int found;
        int (*iterator)(unsigned long node, const char *uname, int depth, void *data);
        void *data;
};

/**
 * fdt_scan_node_by_path - iterator for of_scan_flat_dt_by_path function
 */
static int __init fdt_scan_node_by_path(unsigned long node, const char *uname,
                                        int depth, void *data)
{
        struct fdt_scan_status *st = data;

        /*
         * if scan at the requested fdt node has been completed,
         * return -ENXIO to abort further scanning
         */
        if (depth <= st->depth)
                return -ENXIO;

        /* requested fdt node has been found, so call iterator function */
        if (st->found)
                return st->iterator(node, uname, depth, st->data);

        /* check if scanning automata is entering next level of fdt nodes */
        if (depth == st->depth + 1 &&
            strncmp(st->name, uname, st->namelen) == 0 &&
            uname[st->namelen] == 0) {
                st->depth += 1;
                if (st->name[st->namelen] == 0) {
                        st->found = 1;
                } else {
                        const char *next = st->name + st->namelen + 1;
                        st->name = next;
                        st->namelen = strcspn(next, "/");
                }
                return 0;
        }

        /* scan next fdt node */
        return 0;
}

/**
 * of_scan_flat_dt_by_path - scan flattened tree blob and call callback on each
 *                           child of the given path.
 * @path: path to start searching for children
 * @it: callback function
 * @data: context data pointer
 *
 * This function is used to scan the flattened device-tree starting from the
 * node given by path. It is used to extract information (like reserved
 * memory), which is required on ealy boot before we can unflatten the tree.
 */
int __init of_scan_flat_dt_by_path(const char *path,
        int (*it)(unsigned long node, const char *name, int depth, void *data),
        void *data)
{
        struct fdt_scan_status st = {path, 0, -1, 0, it, data};
        int ret = 0;

        if (initial_boot_params)
                ret = of_scan_flat_dt(fdt_scan_node_by_path, &st);

        if (!st.found)
                return -ENOENT;
        else if (ret == -ENXIO) /* scan has been completed */
                return 0;
        else
                return ret;
}

const char * __init of_flat_dt_get_machine_name(void)
{
        const char *name;
        unsigned long dt_root = of_get_flat_dt_root();

        name = of_get_flat_dt_prop(dt_root, "model", NULL);
        if (!name)
                name = of_get_flat_dt_prop(dt_root, "compatible", NULL);
        return name;
}

/**
 * of_flat_dt_match_machine - Iterate match tables to find matching machine.
 *
 * @default_match: A machine specific ptr to return in case of no match.
 * @get_next_compat: callback function to return next compatible match table.
 *
 * Iterate through machine match tables to find the best match for the machine
 * compatible string in the FDT.
 */
const void * __init of_flat_dt_match_machine(const void *default_match,
                const void * (*get_next_compat)(const char * const**))
{
        const void *data = NULL;
        const void *best_data = default_match;
        const char *const *compat;
        unsigned long dt_root;
        unsigned int best_score = ~1, score = 0;

        dt_root = of_get_flat_dt_root();
        while ((data = get_next_compat(&compat))) {
                score = of_flat_dt_match(dt_root, compat);
                if (score > 0 && score < best_score) {
                        best_data = data;
                        best_score = score;
                }
        }
        if (!best_data) {
                const char *prop;
                long size;

                pr_err("\n unrecognized device tree list:\n[ ");

                prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
                if (prop) {
                        while (size > 0) {
                                printk("'%s' ", prop);
                                size -= strlen(prop) + 1;
                                prop += strlen(prop) + 1;
                        }
                }
                printk("]\n\n");
                return NULL;
        }

        pr_info("Machine model: %s\n", of_flat_dt_get_machine_name());

        return best_data;
}

#ifdef CONFIG_BLK_DEV_INITRD
/**
 * early_init_dt_check_for_initrd - Decode initrd location from flat tree
 * @node: reference to node containing initrd location ('chosen')
 */
static void __init early_init_dt_check_for_initrd(unsigned long node)
{
        u64 start, end;
        unsigned long len;
        __be32 *prop;

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

        prop = of_get_flat_dt_prop(node, "linux,initrd-start", &len);
        if (!prop)
                return;
        start = of_read_number(prop, len/4);

        prop = of_get_flat_dt_prop(node, "linux,initrd-end", &len);
        if (!prop)
                return;
        end = of_read_number(prop, len/4);

        initrd_start = (unsigned long)__va(start);
        initrd_end = (unsigned long)__va(end);
        initrd_below_start_ok = 1;

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

/**
 * early_init_dt_scan_root - fetch the top level address and size cells
 */
int __init early_init_dt_scan_root(unsigned long node, const char *uname,
                                   int depth, void *data)
{
        __be32 *prop;

        if (depth != 0)
                return 0;

        dt_root_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
        dt_root_addr_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;

        prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
        if (prop)
                dt_root_size_cells = be32_to_cpup(prop);
        pr_debug("dt_root_size_cells = %x\n", dt_root_size_cells);

        prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
        if (prop)
                dt_root_addr_cells = be32_to_cpup(prop);
        pr_debug("dt_root_addr_cells = %x\n", dt_root_addr_cells);

        /* break now */
        return 1;
}

u64 __init dt_mem_next_cell(int s, __be32 **cellp)
{
        __be32 *p = *cellp;

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

/**
 * early_init_dt_scan_memory - Look for an parse memory nodes
 */
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);
        __be32 *reg, *endp;
        unsigned long l;

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

        endp = reg + (l / sizeof(__be32));

        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);

                early_init_dt_add_memory_arch(base, size);
        }

        return 0;
}

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 || !data ||
            (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
                return 0;

        early_init_dt_check_for_initrd(node);

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

        /*
         * CONFIG_CMDLINE is meant to be a default in case nothing else
         * managed to set the command line, unless CONFIG_CMDLINE_FORCE
         * is set in which case we override whatever was found earlier.
         */
#ifdef CONFIG_CMDLINE
#ifndef CONFIG_CMDLINE_FORCE
        if (!((char *)data)[0])
#endif
                strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#endif /* CONFIG_CMDLINE */

        pr_debug("Command line is: %s\n", (char*)data);

        /* break now */
        return 1;
}

#ifdef CONFIG_HAVE_MEMBLOCK
void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
{
        const u64 phys_offset = __pa(PAGE_OFFSET);
        base &= PAGE_MASK;
        size &= PAGE_MASK;
        if (base + size < phys_offset) {
                pr_warning("Ignoring memory block 0x%llx - 0x%llx\n",
                           base, base + size);
                return;
        }
        if (base < phys_offset) {
                pr_warning("Ignoring memory range 0x%llx - 0x%llx\n",
                           base, phys_offset);
                size -= phys_offset - base;
                base = phys_offset;
        }
        memblock_add(base, size);
}

/*
 * called from unflatten_device_tree() to bootstrap devicetree itself
 * Architectures can override this definition if memblock isn't used
 */
void * __init __weak early_init_dt_alloc_memory_arch(u64 size, u64 align)
{
        return __va(memblock_alloc(size, align));
}
#endif

bool __init early_init_dt_scan(void *params)
{
        if (!params)
                return false;

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

        /* check device tree validity */
        if (be32_to_cpu(initial_boot_params->magic) != OF_DT_HEADER) {
                initial_boot_params = NULL;
                return false;
        }

        /* Retrieve various information from the /chosen node */
        of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);

        /* Initialize {size,address}-cells info */
        of_scan_flat_dt(early_init_dt_scan_root, NULL);

        /* Setup memory, calling early_init_dt_add_memory_arch */
        of_scan_flat_dt(early_init_dt_scan_memory, NULL);

        return true;
}

/**
 * unflatten_device_tree - create tree of device_nodes from flat blob
 *
 * 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.
 */
void __init unflatten_device_tree(void)
{
        __unflatten_device_tree(initial_boot_params, &of_allnodes,
                                early_init_dt_alloc_memory_arch);

        /* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */
        of_alias_scan(early_init_dt_alloc_memory_arch);
}

/**
 * unflatten_and_copy_device_tree - copy and create tree of device_nodes from flat blob
 *
 * Copies and 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 should only be used when the FDT memory has not been
 * reserved such is the case when the FDT is built-in to the kernel init
 * section. If the FDT memory is reserved already then unflatten_device_tree
 * should be used instead.
 */
void __init unflatten_and_copy_device_tree(void)
{
        int size;
        void *dt;

        if (!initial_boot_params) {
                pr_warn("No valid device tree found, continuing without\n");
                return;
        }

        size = __be32_to_cpu(initial_boot_params->totalsize);
        dt = early_init_dt_alloc_memory_arch(size,
                __alignof__(struct boot_param_header));

        if (dt) {
                memcpy(dt, initial_boot_params, size);
                initial_boot_params = dt;
        }
        unflatten_device_tree();
}

#endif /* CONFIG_OF_EARLY_FLATTREE */