of: Add helper function to check MMIO register endianness

[mirror_ubuntu-jammy-kernel.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/crc32.h>
#include <linux/kernel.h>
#include <linux/initrd.h>
#include <linux/memblock.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/of_reserved_mem.h>
#include <linux/sizes.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/libfdt.h>
#include <linux/debugfs.h>
#include <linux/serial_core.h>
#include <linux/sysfs.h>

#include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
#include <asm/page.h>

/*
 * of_fdt_limit_memory - limit the number of regions in the /memory node
 * @limit: maximum entries
 *
 * Adjust the flattened device tree to have at most 'limit' number of
 * memory entries in the /memory node. This function may be called
 * any time after initial_boot_param is set.
 */
void of_fdt_limit_memory(int limit)
{
        int memory;
        int len;
        const void *val;
        int nr_address_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
        int nr_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
        const uint32_t *addr_prop;
        const uint32_t *size_prop;
        int root_offset;
        int cell_size;

        root_offset = fdt_path_offset(initial_boot_params, "/");
        if (root_offset < 0)
                return;

        addr_prop = fdt_getprop(initial_boot_params, root_offset,
                                "#address-cells", NULL);
        if (addr_prop)
                nr_address_cells = fdt32_to_cpu(*addr_prop);

        size_prop = fdt_getprop(initial_boot_params, root_offset,
                                "#size-cells", NULL);
        if (size_prop)
                nr_size_cells = fdt32_to_cpu(*size_prop);

        cell_size = sizeof(uint32_t)*(nr_address_cells + nr_size_cells);

        memory = fdt_path_offset(initial_boot_params, "/memory");
        if (memory > 0) {
                val = fdt_getprop(initial_boot_params, memory, "reg", &len);
                if (len > limit*cell_size) {
                        len = limit*cell_size;
                        pr_debug("Limiting number of entries to %d\n", limit);
                        fdt_setprop(initial_boot_params, memory, "reg", val,
                                        len);
                }
        }
}

/**
 * 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(const void *blob,
                      unsigned long node, const char *compat)
{
        const char *cp;
        int cplen;
        unsigned long l, score = 0;

        cp = fdt_getprop(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(const void *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
 * @fpsize: Size of the node path up at the current depth.
 */
static void * unflatten_dt_node(void *blob,
                                void *mem,
                                int *poffset,
                                struct device_node *dad,
                                struct device_node **nodepp,
                                unsigned long fpsize,
                                bool dryrun)
{
        const __be32 *p;
        struct device_node *np;
        struct property *pp, **prev_pp = NULL;
        const char *pathp;
        unsigned int l, allocl;
        static int depth = 0;
        int old_depth;
        int offset;
        int has_name = 0;
        int new_format = 0;

        pathp = fdt_get_name(blob, *poffset, &l);
        if (!pathp)
                return mem;

        allocl = l++;

        /* 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 = "";
                } 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 (!dryrun) {
                char *fn;
                of_node_init(np);
                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;
                if (dad != NULL) {
                        np->parent = dad;
                        np->sibling = dad->child;
                        dad->child = np;
                }
        }
        /* process properties */
        for (offset = fdt_first_property_offset(blob, *poffset);
             (offset >= 0);
             (offset = fdt_next_property_offset(blob, offset))) {
                const char *pname;
                u32 sz;

                if (!(p = fdt_getprop_by_offset(blob, offset, &pname, &sz))) {
                        offset = -FDT_ERR_INTERNAL;
                        break;
                }

                if (pname == NULL) {
                        pr_info("Can't find property name in list !\n");
                        break;
                }
                if (strcmp(pname, "name") == 0)
                        has_name = 1;
                pp = unflatten_dt_alloc(&mem, sizeof(struct property),
                                        __alignof__(struct property));
                if (!dryrun) {
                        /* 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(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(p);
                        pp->name = (char *)pname;
                        pp->length = sz;
                        pp->value = (__be32 *)p;
                        *prev_pp = pp;
                        prev_pp = &pp->next;
                }
        }
        /* with version 0x10 we may not have the name property, recreate
         * it here from the unit name if absent
         */
        if (!has_name) {
                const 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 (!dryrun) {
                        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 (!dryrun) {
                *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>";
        }

        old_depth = depth;
        *poffset = fdt_next_node(blob, *poffset, &depth);
        if (depth < 0)
                depth = 0;
        while (*poffset > 0 && depth > old_depth)
                mem = unflatten_dt_node(blob, mem, poffset, np, NULL,
                                        fpsize, dryrun);

        if (*poffset < 0 && *poffset != -FDT_ERR_NOTFOUND)
                pr_err("unflatten: error %d processing FDT\n", *poffset);

        /*
         * Reverse the child list. Some drivers assumes node order matches .dts
         * node order
         */
        if (!dryrun && np->child) {
                struct device_node *child = np->child;
                np->child = NULL;
                while (child) {
                        struct device_node *next = child->sibling;
                        child->sibling = np->child;
                        np->child = child;
                        child = next;
                }
        }

        if (nodepp)
                *nodepp = np;

        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(void *blob,
                             struct device_node **mynodes,
                             void * (*dt_alloc)(u64 size, u64 align))
{
        unsigned long size;
        int start;
        void *mem;

        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", fdt_magic(blob));
        pr_debug("size: %08x\n", fdt_totalsize(blob));
        pr_debug("version: %08x\n", fdt_version(blob));

        if (fdt_check_header(blob)) {
                pr_err("Invalid device tree blob header\n");
                return;
        }

        /* First pass, scan for size */
        start = 0;
        size = (unsigned long)unflatten_dt_node(blob, NULL, &start, NULL, NULL, 0, true);
        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 = 0;
        unflatten_dt_node(blob, mem, &start, NULL, mynodes, 0, false);
        if (be32_to_cpup(mem + size) != 0xdeadbeef)
                pr_warning("End of tree marker overwritten: %08x\n",
                           be32_to_cpup(mem + size));

        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)
{
        __unflatten_device_tree(blob, 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;

void *initial_boot_params;

#ifdef CONFIG_OF_EARLY_FLATTREE

static u32 of_fdt_crc32;

/**
 * res_mem_reserve_reg() - reserve all memory described in 'reg' property
 */
static int __init __reserved_mem_reserve_reg(unsigned long node,
                                             const char *uname)
{
        int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
        phys_addr_t base, size;
        int len;
        const __be32 *prop;
        int nomap, first = 1;

        prop = of_get_flat_dt_prop(node, "reg", &len);
        if (!prop)
                return -ENOENT;

        if (len && len % t_len != 0) {
                pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
                       uname);
                return -EINVAL;
        }

        nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;

        while (len >= t_len) {
                base = dt_mem_next_cell(dt_root_addr_cells, &prop);
                size = dt_mem_next_cell(dt_root_size_cells, &prop);

                if (size &&
                    early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
                        pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %ld MiB\n",
                                uname, &base, (unsigned long)size / SZ_1M);
                else
                        pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %ld MiB\n",
                                uname, &base, (unsigned long)size / SZ_1M);

                len -= t_len;
                if (first) {
                        fdt_reserved_mem_save_node(node, uname, base, size);
                        first = 0;
                }
        }
        return 0;
}

/**
 * __reserved_mem_check_root() - check if #size-cells, #address-cells provided
 * in /reserved-memory matches the values supported by the current implementation,
 * also check if ranges property has been provided
 */
static int __init __reserved_mem_check_root(unsigned long node)
{
        const __be32 *prop;

        prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
        if (!prop || be32_to_cpup(prop) != dt_root_size_cells)
                return -EINVAL;

        prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
        if (!prop || be32_to_cpup(prop) != dt_root_addr_cells)
                return -EINVAL;

        prop = of_get_flat_dt_prop(node, "ranges", NULL);
        if (!prop)
                return -EINVAL;
        return 0;
}

/**
 * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
 */
static int __init __fdt_scan_reserved_mem(unsigned long node, const char *uname,
                                          int depth, void *data)
{
        static int found;
        const char *status;
        int err;

        if (!found && depth == 1 && strcmp(uname, "reserved-memory") == 0) {
                if (__reserved_mem_check_root(node) != 0) {
                        pr_err("Reserved memory: unsupported node format, ignoring\n");
                        /* break scan */
                        return 1;
                }
                found = 1;
                /* scan next node */
                return 0;
        } else if (!found) {
                /* scan next node */
                return 0;
        } else if (found && depth < 2) {
                /* scanning of /reserved-memory has been finished */
                return 1;
        }

        status = of_get_flat_dt_prop(node, "status", NULL);
        if (status && strcmp(status, "okay") != 0 && strcmp(status, "ok") != 0)
                return 0;

        err = __reserved_mem_reserve_reg(node, uname);
        if (err == -ENOENT && of_get_flat_dt_prop(node, "size", NULL))
                fdt_reserved_mem_save_node(node, uname, 0, 0);

        /* scan next node */
        return 0;
}

/**
 * early_init_fdt_scan_reserved_mem() - create reserved memory regions
 *
 * This function grabs memory from early allocator for device exclusive use
 * defined in device tree structures. It should be called by arch specific code
 * once the early allocator (i.e. memblock) has been fully activated.
 */
void __init early_init_fdt_scan_reserved_mem(void)
{
        int n;
        u64 base, size;

        if (!initial_boot_params)
                return;

        /* Reserve the dtb region */
        early_init_dt_reserve_memory_arch(__pa(initial_boot_params),
                                          fdt_totalsize(initial_boot_params),
                                          0);

        /* Process header /memreserve/ fields */
        for (n = 0; ; n++) {
                fdt_get_mem_rsv(initial_boot_params, n, &base, &size);
                if (!size)
                        break;
                early_init_dt_reserve_memory_arch(base, size, 0);
        }

        of_scan_flat_dt(__fdt_scan_reserved_mem, NULL);
        fdt_init_reserved_mem();
}

/**
 * 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)
{
        const void *blob = initial_boot_params;
        const char *pathp;
        int offset, rc = 0, depth = -1;

        for (offset = fdt_next_node(blob, -1, &depth);
             offset >= 0 && depth >= 0 && !rc;
             offset = fdt_next_node(blob, offset, &depth)) {

                pathp = fdt_get_name(blob, offset, NULL);
                if (*pathp == '/')
                        pathp = kbasename(pathp);
                rc = it(offset, pathp, depth, data);
        }
        return rc;
}

/**
 * of_get_flat_dt_root - find the root node in the flat blob
 */
unsigned long __init of_get_flat_dt_root(void)
{
        return 0;
}

/**
 * of_get_flat_dt_size - Return the total size of the FDT
 */
int __init of_get_flat_dt_size(void)
{
        return fdt_totalsize(initial_boot_params);
}

/**
 * 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
 */
const void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
                                       int *size)
{
        return fdt_getprop(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;
};

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;
                int 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;
        int len;
        const __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 */

#ifdef CONFIG_SERIAL_EARLYCON
extern struct of_device_id __earlycon_of_table[];

static int __init early_init_dt_scan_chosen_serial(void)
{
        int offset;
        const char *p;
        int l;
        const struct of_device_id *match = __earlycon_of_table;
        const void *fdt = initial_boot_params;

        offset = fdt_path_offset(fdt, "/chosen");
        if (offset < 0)
                offset = fdt_path_offset(fdt, "/chosen@0");
        if (offset < 0)
                return -ENOENT;

        p = fdt_getprop(fdt, offset, "stdout-path", &l);
        if (!p)
                p = fdt_getprop(fdt, offset, "linux,stdout-path", &l);
        if (!p || !l)
                return -ENOENT;

        /* Get the node specified by stdout-path */
        offset = fdt_path_offset(fdt, p);
        if (offset < 0)
                return -ENODEV;

        while (match->compatible[0]) {
                unsigned long addr;
                if (fdt_node_check_compatible(fdt, offset, match->compatible)) {
                        match++;
                        continue;
                }

                addr = fdt_translate_address(fdt, offset);
                if (!addr)
                        return -ENXIO;

                of_setup_earlycon(addr, match->data);
                return 0;
        }
        return -ENODEV;
}

static int __init setup_of_earlycon(char *buf)
{
        if (buf)
                return 0;

        return early_init_dt_scan_chosen_serial();
}
early_param("earlycon", setup_of_earlycon);
#endif

/**
 * 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)
{
        const __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, const __be32 **cellp)
{
        const __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)
{
        const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
        const __be32 *reg, *endp;
        int 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 (!IS_ENABLED(CONFIG_PPC32) || 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 %d,\n", uname, l);

        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)
{
        int l;
        const 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
#define MAX_PHYS_ADDR   ((phys_addr_t)~0)

void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
{
        const u64 phys_offset = __pa(PAGE_OFFSET);

        if (!PAGE_ALIGNED(base)) {
                if (size < PAGE_SIZE - (base & ~PAGE_MASK)) {
                        pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
                                base, base + size);
                        return;
                }
                size -= PAGE_SIZE - (base & ~PAGE_MASK);
                base = PAGE_ALIGN(base);
        }
        size &= PAGE_MASK;

        if (base > MAX_PHYS_ADDR) {
                pr_warning("Ignoring memory block 0x%llx - 0x%llx\n",
                                base, base + size);
                return;
        }

        if (base + size - 1 > MAX_PHYS_ADDR) {
                pr_warning("Ignoring memory range 0x%llx - 0x%llx\n",
                                ((u64)MAX_PHYS_ADDR) + 1, base + size);
                size = MAX_PHYS_ADDR - base + 1;
        }

        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);
}

int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
                                        phys_addr_t size, bool nomap)
{
        if (nomap)
                return memblock_remove(base, size);
        return memblock_reserve(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));
}
#else
int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
                                        phys_addr_t size, bool nomap)
{
        pr_err("Reserved memory not supported, ignoring range 0x%pa - 0x%pa%s\n",
                  &base, &size, nomap ? " (nomap)" : "");
        return -ENOSYS;
}
#endif

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

        /* check device tree validity */
        if (fdt_check_header(params))
                return false;

        /* Setup flat device-tree pointer */
        initial_boot_params = params;
        of_fdt_crc32 = crc32_be(~0, initial_boot_params,
                                fdt_totalsize(initial_boot_params));
        return true;
}


void __init early_init_dt_scan_nodes(void)
{
        /* 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);
}

bool __init early_init_dt_scan(void *params)
{
        bool status;

        status = early_init_dt_verify(params);
        if (!status)
                return false;

        early_init_dt_scan_nodes();
        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_root,
                                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 = fdt_totalsize(initial_boot_params);
        dt = early_init_dt_alloc_memory_arch(size,
                                             roundup_pow_of_two(FDT_V17_SIZE));

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

#ifdef CONFIG_SYSFS
static ssize_t of_fdt_raw_read(struct file *filp, struct kobject *kobj,
                               struct bin_attribute *bin_attr,
                               char *buf, loff_t off, size_t count)
{
        memcpy(buf, initial_boot_params + off, count);
        return count;
}

static int __init of_fdt_raw_init(void)
{
        static struct bin_attribute of_fdt_raw_attr =
                __BIN_ATTR(fdt, S_IRUSR, of_fdt_raw_read, NULL, 0);

        if (!initial_boot_params)
                return 0;

        if (of_fdt_crc32 != crc32_be(~0, initial_boot_params,
                                     fdt_totalsize(initial_boot_params))) {
                pr_warn("fdt: not creating '/sys/firmware/fdt': CRC check failed\n");
                return 0;
        }
        of_fdt_raw_attr.size = fdt_totalsize(initial_boot_params);
        return sysfs_create_bin_file(firmware_kobj, &of_fdt_raw_attr);
}
late_initcall(of_fdt_raw_init);
#endif

#endif /* CONFIG_OF_EARLY_FLATTREE */