/*
 * csr1212.c -- IEEE 1212 Control and Status Register support for Linux
 *
 * Copyright (C) 2003 Francois Retief <fgretief@sun.ac.za>
 *                    Steve Kinneberg <kinnebergsteve@acmsystems.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *    1. Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *    2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *    3. The name of the author may not be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


/* TODO List:
 * - Verify interface consistency: i.e., public functions that take a size
 *   parameter expect size to be in bytes.
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/kmemcheck.h>
#include <linux/string.h>
#include <asm/bug.h>
#include <asm/byteorder.h>

#include "csr1212.h"


/* Permitted key type for each key id */
#define __I (1 << CSR1212_KV_TYPE_IMMEDIATE)
#define __C (1 << CSR1212_KV_TYPE_CSR_OFFSET)
#define __D (1 << CSR1212_KV_TYPE_DIRECTORY)
#define __L (1 << CSR1212_KV_TYPE_LEAF)
static const u8 csr1212_key_id_type_map[0x30] = {
        __C,                    /* used by Apple iSight */
        __D | __L,              /* Descriptor */
        __I | __D | __L,        /* Bus_Dependent_Info */
        __I | __D | __L,        /* Vendor */
        __I,                    /* Hardware_Version */
        0, 0,                   /* Reserved */
        __D | __L | __I,        /* Module */
        __I, 0, 0, 0,           /* used by Apple iSight, Reserved */
        __I,                    /* Node_Capabilities */
        __L,                    /* EUI_64 */
        0, 0, 0,                /* Reserved */
        __D,                    /* Unit */
        __I,                    /* Specifier_ID */
        __I,                    /* Version */
        __I | __C | __D | __L,  /* Dependent_Info */
        __L,                    /* Unit_Location */
        0,                      /* Reserved */
        __I,                    /* Model */
        __D,                    /* Instance */
        __L,                    /* Keyword */
        __D,                    /* Feature */
        __L,                    /* Extended_ROM */
        __I,                    /* Extended_Key_Specifier_ID */
        __I,                    /* Extended_Key */
        __I | __C | __D | __L,  /* Extended_Data */
        __L,                    /* Modifiable_Descriptor */
        __I,                    /* Directory_ID */
        __I,                    /* Revision */
};
#undef __I
#undef __C
#undef __D
#undef __L


#define quads_to_bytes(_q) ((_q) * sizeof(u32))
#define bytes_to_quads(_b) DIV_ROUND_UP(_b, sizeof(u32))

static void free_keyval(struct csr1212_keyval *kv)
{
        if ((kv->key.type == CSR1212_KV_TYPE_LEAF) &&
            (kv->key.id != CSR1212_KV_ID_EXTENDED_ROM))
                CSR1212_FREE(kv->value.leaf.data);

        CSR1212_FREE(kv);
}

static u16 csr1212_crc16(const u32 *buffer, size_t length)
{
        int shift;
        u32 data;
        u16 sum, crc = 0;

        for (; length; length--) {
                data = be32_to_cpu(*buffer);
                buffer++;
                for (shift = 28; shift >= 0; shift -= 4 ) {
                        sum = ((crc >> 12) ^ (data >> shift)) & 0xf;
                        crc = (crc << 4) ^ (sum << 12) ^ (sum << 5) ^ (sum);
                }
                crc &= 0xffff;
        }

        return cpu_to_be16(crc);
}

/* Microsoft computes the CRC with the bytes in reverse order. */
static u16 csr1212_msft_crc16(const u32 *buffer, size_t length)
{
        int shift;
        u32 data;
        u16 sum, crc = 0;

        for (; length; length--) {
                data = le32_to_cpu(*buffer);
                buffer++;
                for (shift = 28; shift >= 0; shift -= 4 ) {
                        sum = ((crc >> 12) ^ (data >> shift)) & 0xf;
                        crc = (crc << 4) ^ (sum << 12) ^ (sum << 5) ^ (sum);
                }
                crc &= 0xffff;
        }

        return cpu_to_be16(crc);
}

static struct csr1212_dentry *
csr1212_find_keyval(struct csr1212_keyval *dir, struct csr1212_keyval *kv)
{
        struct csr1212_dentry *pos;

        for (pos = dir->value.directory.dentries_head;
             pos != NULL; pos = pos->next)
                if (pos->kv == kv)
                        return pos;
        return NULL;
}

static struct csr1212_keyval *
csr1212_find_keyval_offset(struct csr1212_keyval *kv_list, u32 offset)
{
        struct csr1212_keyval *kv;

        for (kv = kv_list->next; kv && (kv != kv_list); kv = kv->next)
                if (kv->offset == offset)
                        return kv;
        return NULL;
}


/* Creation Routines */

struct csr1212_csr *csr1212_create_csr(struct csr1212_bus_ops *ops,
                                       size_t bus_info_size, void *private)
{
        struct csr1212_csr *csr;

        csr = CSR1212_MALLOC(sizeof(*csr));
        if (!csr)
                return NULL;

        csr->cache_head =
                csr1212_rom_cache_malloc(CSR1212_CONFIG_ROM_SPACE_OFFSET,
                                         CSR1212_CONFIG_ROM_SPACE_SIZE);
        if (!csr->cache_head) {
                CSR1212_FREE(csr);
                return NULL;
        }

        /* The keyval key id is not used for the root node, but a valid key id
         * that can be used for a directory needs to be passed to
         * csr1212_new_directory(). */
        csr->root_kv = csr1212_new_directory(CSR1212_KV_ID_VENDOR);
        if (!csr->root_kv) {
                CSR1212_FREE(csr->cache_head);
                CSR1212_FREE(csr);
                return NULL;
        }

        csr->bus_info_data = csr->cache_head->data;
        csr->bus_info_len = bus_info_size;
        csr->crc_len = bus_info_size;
        csr->ops = ops;
        csr->private = private;
        csr->cache_tail = csr->cache_head;

        return csr;
}

void csr1212_init_local_csr(struct csr1212_csr *csr,
                            const u32 *bus_info_data, int max_rom)
{
        static const int mr_map[] = { 4, 64, 1024, 0 };

        BUG_ON(max_rom & ~0x3);
        csr->max_rom = mr_map[max_rom];
        memcpy(csr->bus_info_data, bus_info_data, csr->bus_info_len);
}

static struct csr1212_keyval *csr1212_new_keyval(u8 type, u8 key)
{
        struct csr1212_keyval *kv;

        if (key < 0x30 && ((csr1212_key_id_type_map[key] & (1 << type)) == 0))
                return NULL;

        kv = CSR1212_MALLOC(sizeof(*kv));
        if (!kv)
                return NULL;

        atomic_set(&kv->refcnt, 1);
        kv->key.type = type;
        kv->key.id = key;
        kv->associate = NULL;
        kv->next = NULL;
        kv->prev = NULL;
        kv->offset = 0;
        kv->valid = 0;
        return kv;
}

struct csr1212_keyval *csr1212_new_immediate(u8 key, u32 value)
{
        struct csr1212_keyval *kv;

        kv = csr1212_new_keyval(CSR1212_KV_TYPE_IMMEDIATE, key);
        if (!kv)
                return NULL;

        kv->value.immediate = value;
        kv->valid = 1;
        return kv;
}

static struct csr1212_keyval *
csr1212_new_leaf(u8 key, const void *data, size_t data_len)
{
        struct csr1212_keyval *kv;

        kv = csr1212_new_keyval(CSR1212_KV_TYPE_LEAF, key);
        if (!kv)
                return NULL;

        if (data_len > 0) {
                kv->value.leaf.data = CSR1212_MALLOC(data_len);
                if (!kv->value.leaf.data) {
                        CSR1212_FREE(kv);
                        return NULL;
                }

                if (data)
                        memcpy(kv->value.leaf.data, data, data_len);
        } else {
                kv->value.leaf.data = NULL;
        }

        kv->value.leaf.len = bytes_to_quads(data_len);
        kv->offset = 0;
        kv->valid = 1;

        return kv;
}

static struct csr1212_keyval *
csr1212_new_csr_offset(u8 key, u32 csr_offset)
{
        struct csr1212_keyval *kv;

        kv = csr1212_new_keyval(CSR1212_KV_TYPE_CSR_OFFSET, key);
        if (!kv)
                return NULL;

        kv->value.csr_offset = csr_offset;

        kv->offset = 0;
        kv->valid = 1;
        return kv;
}

struct csr1212_keyval *csr1212_new_directory(u8 key)
{
        struct csr1212_keyval *kv;

        kv = csr1212_new_keyval(CSR1212_KV_TYPE_DIRECTORY, key);
        if (!kv)
                return NULL;

        kv->value.directory.len = 0;
        kv->offset = 0;
        kv->value.directory.dentries_head = NULL;
        kv->value.directory.dentries_tail = NULL;
        kv->valid = 1;
        return kv;
}

void csr1212_associate_keyval(struct csr1212_keyval *kv,
                              struct csr1212_keyval *associate)
{
        BUG_ON(!kv || !associate || kv->key.id == CSR1212_KV_ID_DESCRIPTOR ||
               (associate->key.id != CSR1212_KV_ID_DESCRIPTOR &&
                associate->key.id != CSR1212_KV_ID_DEPENDENT_INFO &&
                associate->key.id != CSR1212_KV_ID_EXTENDED_KEY &&
                associate->key.id != CSR1212_KV_ID_EXTENDED_DATA &&
                associate->key.id < 0x30) ||
               (kv->key.id == CSR1212_KV_ID_EXTENDED_KEY_SPECIFIER_ID &&
                associate->key.id != CSR1212_KV_ID_EXTENDED_KEY) ||
               (kv->key.id == CSR1212_KV_ID_EXTENDED_KEY &&
                associate->key.id != CSR1212_KV_ID_EXTENDED_DATA) ||
               (associate->key.id == CSR1212_KV_ID_EXTENDED_KEY &&
                kv->key.id != CSR1212_KV_ID_EXTENDED_KEY_SPECIFIER_ID) ||
               (associate->key.id == CSR1212_KV_ID_EXTENDED_DATA &&
                kv->key.id != CSR1212_KV_ID_EXTENDED_KEY));

        if (kv->associate)
                csr1212_release_keyval(kv->associate);

        csr1212_keep_keyval(associate);
        kv->associate = associate;
}

static int __csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir,
                                                struct csr1212_keyval *kv,
                                                bool keep_keyval)
{
        struct csr1212_dentry *dentry;

        BUG_ON(!kv || !dir || dir->key.type != CSR1212_KV_TYPE_DIRECTORY);

        dentry = CSR1212_MALLOC(sizeof(*dentry));
        if (!dentry)
                return -ENOMEM;

        if (keep_keyval)
                csr1212_keep_keyval(kv);
        dentry->kv = kv;

        dentry->next = NULL;
        dentry->prev = dir->value.directory.dentries_tail;

        if (!dir->value.directory.dentries_head)
                dir->value.directory.dentries_head = dentry;

        if (dir->value.directory.dentries_tail)
                dir->value.directory.dentries_tail->next = dentry;
        dir->value.directory.dentries_tail = dentry;

        return CSR1212_SUCCESS;
}

int csr1212_attach_keyval_to_directory(struct csr1212_keyval *dir,
                                       struct csr1212_keyval *kv)
{
        return __csr1212_attach_keyval_to_directory(dir, kv, true);
}

#define CSR1212_DESCRIPTOR_LEAF_DATA(kv) \
        (&((kv)->value.leaf.data[1]))

#define CSR1212_DESCRIPTOR_LEAF_SET_TYPE(kv, type) \
        ((kv)->value.leaf.data[0] = \
         cpu_to_be32(CSR1212_DESCRIPTOR_LEAF_SPECIFIER_ID(kv) | \
                     ((type) << CSR1212_DESCRIPTOR_LEAF_TYPE_SHIFT)))
#define CSR1212_DESCRIPTOR_LEAF_SET_SPECIFIER_ID(kv, spec_id) \
        ((kv)->value.leaf.data[0] = \
         cpu_to_be32((CSR1212_DESCRIPTOR_LEAF_TYPE(kv) << \
                      CSR1212_DESCRIPTOR_LEAF_TYPE_SHIFT) | \
                     ((spec_id) & CSR1212_DESCRIPTOR_LEAF_SPECIFIER_ID_MASK)))

static struct csr1212_keyval *
csr1212_new_descriptor_leaf(u8 dtype, u32 specifier_id,
                            const void *data, size_t data_len)
{
        struct csr1212_keyval *kv;

        kv = csr1212_new_leaf(CSR1212_KV_ID_DESCRIPTOR, NULL,
                              data_len + CSR1212_DESCRIPTOR_LEAF_OVERHEAD);
        if (!kv)
                return NULL;

        kmemcheck_annotate_variable(kv->value.leaf.data[0]);
        CSR1212_DESCRIPTOR_LEAF_SET_TYPE(kv, dtype);
        CSR1212_DESCRIPTOR_LEAF_SET_SPECIFIER_ID(kv, specifier_id);

        if (data)
                memcpy(CSR1212_DESCRIPTOR_LEAF_DATA(kv), data, data_len);

        return kv;
}

/* Check if string conforms to minimal ASCII as per IEEE 1212 clause 7.4 */
static int csr1212_check_minimal_ascii(const char *s)
{
        static const char minimal_ascii_table[] = {
                                        /*  1   2   4   8  16  32  64  128 */
                128,                    /* --, --, --, --, --, --, --, 07, */
                4 + 16 + 32,            /* --, --, 0a, --, 0C, 0D, --, --, */
                0,                      /* --, --, --, --, --, --, --, --, */
                0,                      /* --, --, --, --, --, --, --, --, */
                255 - 8 - 16,           /* 20, 21, 22, --, --, 25, 26, 27, */
                255,                    /* 28, 29, 2a, 2b, 2c, 2d, 2e, 2f, */
                255,                    /* 30, 31, 32, 33, 34, 35, 36, 37, */
                255,                    /* 38, 39, 3a, 3b, 3c, 3d, 3e, 3f, */
                255,                    /* 40, 41, 42, 43, 44, 45, 46, 47, */
                255,                    /* 48, 49, 4a, 4b, 4c, 4d, 4e, 4f, */
                255,                    /* 50, 51, 52, 53, 54, 55, 56, 57, */
                1 + 2 + 4 + 128,        /* 58, 59, 5a, --, --, --, --, 5f, */
                255 - 1,                /* --, 61, 62, 63, 64, 65, 66, 67, */
                255,                    /* 68, 69, 6a, 6b, 6c, 6d, 6e, 6f, */
                255,                    /* 70, 71, 72, 73, 74, 75, 76, 77, */
                1 + 2 + 4,              /* 78, 79, 7a, --, --, --, --, --, */
        };
        int i, j;

        for (; *s; s++) {
                i = *s >> 3;            /*  i = *s / 8;         */
                j = 1 << (*s & 3);      /*  j = 1 << (*s % 8);  */

                if (i >= ARRAY_SIZE(minimal_ascii_table) ||
                    !(minimal_ascii_table[i] & j))
                        return -EINVAL;
        }
        return 0;
}

/* IEEE 1212 clause 7.5.4.1 textual descriptors (English, minimal ASCII) */
struct csr1212_keyval *csr1212_new_string_descriptor_leaf(const char *s)
{
        struct csr1212_keyval *kv;
        u32 *text;
        size_t str_len, quads;

        if (!s || !*s || csr1212_check_minimal_ascii(s))
                return NULL;

        str_len = strlen(s);
        quads = bytes_to_quads(str_len);
        kv = csr1212_new_descriptor_leaf(0, 0, NULL, quads_to_bytes(quads) +
                                      CSR1212_TEXTUAL_DESCRIPTOR_LEAF_OVERHEAD);
        if (!kv)
                return NULL;

        kv->value.leaf.data[1] = 0;     /* width, character_set, language */
        text = CSR1212_TEXTUAL_DESCRIPTOR_LEAF_DATA(kv);
        text[quads - 1] = 0;            /* padding */
        memcpy(text, s, str_len);

        return kv;
}


/* Destruction Routines */

void csr1212_detach_keyval_from_directory(struct csr1212_keyval *dir,
                                          struct csr1212_keyval *kv)
{
        struct csr1212_dentry *dentry;

        if (!kv || !dir || dir->key.type != CSR1212_KV_TYPE_DIRECTORY)
                return;

        dentry = csr1212_find_keyval(dir, kv);

        if (!dentry)
                return;

        if (dentry->prev)
                dentry->prev->next = dentry->next;
        if (dentry->next)
                dentry->next->prev = dentry->prev;
        if (dir->value.directory.dentries_head == dentry)
                dir->value.directory.dentries_head = dentry->next;
        if (dir->value.directory.dentries_tail == dentry)
                dir->value.directory.dentries_tail = dentry->prev;

        CSR1212_FREE(dentry);

        csr1212_release_keyval(kv);
}

/* This function is used to free the memory taken by a keyval.  If the given
 * keyval is a directory type, then any keyvals contained in that directory
 * will be destroyed as well if noone holds a reference on them.  By means of
 * list manipulation, this routine will descend a directory structure in a
 * non-recursive manner. */
void csr1212_release_keyval(struct csr1212_keyval *kv)
{
        struct csr1212_keyval *k, *a;
        struct csr1212_dentry dentry;
        struct csr1212_dentry *head, *tail;

        if (!atomic_dec_and_test(&kv->refcnt))
                return;

        dentry.kv = kv;
        dentry.next = NULL;
        dentry.prev = NULL;

        head = &dentry;
        tail = head;

        while (head) {
                k = head->kv;

                while (k) {
                        /* must not dec_and_test kv->refcnt again */
                        if (k != kv && !atomic_dec_and_test(&k->refcnt))
                                break;

                        a = k->associate;

                        if (k->key.type == CSR1212_KV_TYPE_DIRECTORY) {
                                /* If the current entry is a directory, move all
                                 * the entries to the destruction list. */
                                if (k->value.directory.dentries_head) {
                                        tail->next =
                                            k->value.directory.dentries_head;
                                        k->value.directory.dentries_head->prev =
                                            tail;
                                        tail = k->value.directory.dentries_tail;
                                }
                        }
                        free_keyval(k);
                        k = a;
                }

                head = head->next;
                if (head) {
                        if (head->prev && head->prev != &dentry)
                                CSR1212_FREE(head->prev);
                        head->prev = NULL;
                } else if (tail != &dentry) {
                        CSR1212_FREE(tail);
                }
        }
}

void csr1212_destroy_csr(struct csr1212_csr *csr)
{
        struct csr1212_csr_rom_cache *c, *oc;
        struct csr1212_cache_region *cr, *ocr;

        csr1212_release_keyval(csr->root_kv);

        c = csr->cache_head;
        while (c) {
                oc = c;
                cr = c->filled_head;
                while (cr) {
                        ocr = cr;
                        cr = cr->next;
                        CSR1212_FREE(ocr);
                }
                c = c->next;
                CSR1212_FREE(oc);
        }

        CSR1212_FREE(csr);
}


/* CSR Image Creation */

static int csr1212_append_new_cache(struct csr1212_csr *csr, size_t romsize)
{
        struct csr1212_csr_rom_cache *cache;
        u64 csr_addr;

        BUG_ON(!csr || !csr->ops || !csr->ops->allocate_addr_range ||
               !csr->ops->release_addr || csr->max_rom < 1);

        /* ROM size must be a multiple of csr->max_rom */
        romsize = (romsize + (csr->max_rom - 1)) & ~(csr->max_rom - 1);

        csr_addr = csr->ops->allocate_addr_range(romsize, csr->max_rom,
                                                 csr->private);
        if (csr_addr == CSR1212_INVALID_ADDR_SPACE)
                return -ENOMEM;

        if (csr_addr < CSR1212_REGISTER_SPACE_BASE) {
                /* Invalid address returned from allocate_addr_range(). */
                csr->ops->release_addr(csr_addr, csr->private);
                return -ENOMEM;
        }

        cache = csr1212_rom_cache_malloc(csr_addr - CSR1212_REGISTER_SPACE_BASE,
                                         romsize);
        if (!cache) {
                csr->ops->release_addr(csr_addr, csr->private);
                return -ENOMEM;
        }

        cache->ext_rom = csr1212_new_keyval(CSR1212_KV_TYPE_LEAF,
                                            CSR1212_KV_ID_EXTENDED_ROM);
        if (!cache->ext_rom) {
                csr->ops->release_addr(csr_addr, csr->private);
                CSR1212_FREE(cache);
                return -ENOMEM;
        }

        if (csr1212_attach_keyval_to_directory(csr->root_kv, cache->ext_rom) !=
            CSR1212_SUCCESS) {
                csr1212_release_keyval(cache->ext_rom);
                csr->ops->release_addr(csr_addr, csr->private);
                CSR1212_FREE(cache);
                return -ENOMEM;
        }
        cache->ext_rom->offset = csr_addr - CSR1212_REGISTER_SPACE_BASE;
        cache->ext_rom->value.leaf.len = -1;
        cache->ext_rom->value.leaf.data = cache->data;

        /* Add cache to tail of cache list */
        cache->prev = csr->cache_tail;
        csr->cache_tail->next = cache;
        csr->cache_tail = cache;
        return CSR1212_SUCCESS;
}

static void csr1212_remove_cache(struct csr1212_csr *csr,
                                 struct csr1212_csr_rom_cache *cache)
{
        if (csr->cache_head == cache)
                csr->cache_head = cache->next;
        if (csr->cache_tail == cache)
                csr->cache_tail = cache->prev;

        if (cache->prev)
                cache->prev->next = cache->next;
        if (cache->next)
                cache->next->prev = cache->prev;

        if (cache->ext_rom) {
                csr1212_detach_keyval_from_directory(csr->root_kv,
                                                     cache->ext_rom);
                csr1212_release_keyval(cache->ext_rom);
        }

        CSR1212_FREE(cache);
}

static int csr1212_generate_layout_subdir(struct csr1212_keyval *dir,
                                          struct csr1212_keyval **layout_tail)
{
        struct csr1212_dentry *dentry;
        struct csr1212_keyval *dkv;
        struct csr1212_keyval *last_extkey_spec = NULL;
        struct csr1212_keyval *last_extkey = NULL;
        int num_entries = 0;

        for (dentry = dir->value.directory.dentries_head; dentry;
             dentry = dentry->next) {
                for (dkv = dentry->kv; dkv; dkv = dkv->associate) {
                        /* Special Case: Extended Key Specifier_ID */
                        if (dkv->key.id ==
                            CSR1212_KV_ID_EXTENDED_KEY_SPECIFIER_ID) {
                                if (last_extkey_spec == NULL)
                                        last_extkey_spec = dkv;
                                else if (dkv->value.immediate !=
                                         last_extkey_spec->value.immediate)
                                        last_extkey_spec = dkv;
                                else
                                        continue;
                        /* Special Case: Extended Key */
                        } else if (dkv->key.id == CSR1212_KV_ID_EXTENDED_KEY) {
                                if (last_extkey == NULL)
                                        last_extkey = dkv;
                                else if (dkv->value.immediate !=
                                         last_extkey->value.immediate)
                                        last_extkey = dkv;
                                else
                                        continue;
                        }

                        num_entries += 1;

                        switch (dkv->key.type) {
                        default:
                        case CSR1212_KV_TYPE_IMMEDIATE:
                        case CSR1212_KV_TYPE_CSR_OFFSET:
                                break;
                        case CSR1212_KV_TYPE_LEAF:
                        case CSR1212_KV_TYPE_DIRECTORY:
                                /* Remove from list */
                                if (dkv->prev && (dkv->prev->next == dkv))
                                        dkv->prev->next = dkv->next;
                                if (dkv->next && (dkv->next->prev == dkv))
                                        dkv->next->prev = dkv->prev;
                                //if (dkv == *layout_tail)
                                //      *layout_tail = dkv->prev;

                                /* Special case: Extended ROM leafs */
                                if (dkv->key.id == CSR1212_KV_ID_EXTENDED_ROM) {
                                        dkv->value.leaf.len = -1;
                                        /* Don't add Extended ROM leafs in the
                                         * layout list, they are handled
                                         * differently. */
                                        break;
                                }

                                /* Add to tail of list */
                                dkv->next = NULL;
                                dkv->prev = *layout_tail;
                                (*layout_tail)->next = dkv;
                                *layout_tail = dkv;
                                break;
                        }
                }
        }
        return num_entries;
}

static size_t csr1212_generate_layout_order(struct csr1212_keyval *kv)
{
        struct csr1212_keyval *ltail = kv;
        size_t agg_size = 0;

        while (kv) {
                switch (kv->key.type) {
                case CSR1212_KV_TYPE_LEAF:
                        /* Add 1 quadlet for crc/len field */
                        agg_size += kv->value.leaf.len + 1;
                        break;

                case CSR1212_KV_TYPE_DIRECTORY:
                        kv->value.directory.len =
                                csr1212_generate_layout_subdir(kv, &ltail);
                        /* Add 1 quadlet for crc/len field */
                        agg_size += kv->value.directory.len + 1;
                        break;
                }
                kv = kv->next;
        }
        return quads_to_bytes(agg_size);
}

static struct csr1212_keyval *
csr1212_generate_positions(struct csr1212_csr_rom_cache *cache,
                           struct csr1212_keyval *start_kv, int start_pos)
{
        struct csr1212_keyval *kv = start_kv;
        struct csr1212_keyval *okv = start_kv;
        int pos = start_pos;
        int kv_len = 0, okv_len = 0;

        cache->layout_head = kv;

        while (kv && pos < cache->size) {
                /* Special case: Extended ROM leafs */
                if (kv->key.id != CSR1212_KV_ID_EXTENDED_ROM)
                        kv->offset = cache->offset + pos;

                switch (kv->key.type) {
                case CSR1212_KV_TYPE_LEAF:
                        kv_len = kv->value.leaf.len;
                        break;

                case CSR1212_KV_TYPE_DIRECTORY:
                        kv_len = kv->value.directory.len;
                        break;

                default:
                        /* Should never get here */
                        WARN_ON(1);
                        break;
                }

                pos += quads_to_bytes(kv_len + 1);

                if (pos <= cache->size) {
                        okv = kv;
                        okv_len = kv_len;
                        kv = kv->next;
                }
        }

        cache->layout_tail = okv;
        cache->len = okv->offset - cache->offset + quads_to_bytes(okv_len + 1);

        return kv;
}

#define CSR1212_KV_KEY_SHIFT            24
#define CSR1212_KV_KEY_TYPE_SHIFT       6
#define CSR1212_KV_KEY_ID_MASK          0x3f
#define CSR1212_KV_KEY_TYPE_MASK        0x3     /* after shift */

static void
csr1212_generate_tree_subdir(struct csr1212_keyval *dir, u32 *data_buffer)
{
        struct csr1212_dentry *dentry;
        struct csr1212_keyval *last_extkey_spec = NULL;
        struct csr1212_keyval *last_extkey = NULL;
        int index = 0;

        for (dentry = dir->value.directory.dentries_head;
             dentry;
             dentry = dentry->next) {
                struct csr1212_keyval *a;

                for (a = dentry->kv; a; a = a->associate) {
                        u32 value = 0;

                        /* Special Case: Extended Key Specifier_ID */
                        if (a->key.id ==
                            CSR1212_KV_ID_EXTENDED_KEY_SPECIFIER_ID) {
                                if (last_extkey_spec == NULL)
                                        last_extkey_spec = a;
                                else if (a->value.immediate !=
                                         last_extkey_spec->value.immediate)
                                        last_extkey_spec = a;
                                else
                                        continue;

                        /* Special Case: Extended Key */
                        } else if (a->key.id == CSR1212_KV_ID_EXTENDED_KEY) {
                                if (last_extkey == NULL)
                                        last_extkey = a;
                                else if (a->value.immediate !=
                                         last_extkey->value.immediate)
                                        last_extkey = a;
                                else
                                        continue;
                        }

                        switch (a->key.type) {
                        case CSR1212_KV_TYPE_IMMEDIATE:
                                value = a->value.immediate;
                                break;
                        case CSR1212_KV_TYPE_CSR_OFFSET:
                                value = a->value.csr_offset;
                                break;
                        case CSR1212_KV_TYPE_LEAF:
                                value = a->offset;
                                value -= dir->offset + quads_to_bytes(1+index);
                                value = bytes_to_quads(value);
                                break;
                        case CSR1212_KV_TYPE_DIRECTORY:
                                value = a->offset;
                                value -= dir->offset + quads_to_bytes(1+index);
                                value = bytes_to_quads(value);
                                break;
                        default:
                                /* Should never get here */
                                WARN_ON(1);
                                break;
                        }

                        value |= (a->key.id & CSR1212_KV_KEY_ID_MASK) <<
                                 CSR1212_KV_KEY_SHIFT;
                        value |= (a->key.type & CSR1212_KV_KEY_TYPE_MASK) <<
                                 (CSR1212_KV_KEY_SHIFT +
                                  CSR1212_KV_KEY_TYPE_SHIFT);
                        data_buffer[index] = cpu_to_be32(value);
                        index++;
                }
        }
}

struct csr1212_keyval_img {
        u16 length;
        u16 crc;

        /* Must be last */
        u32 data[0];    /* older gcc can't handle [] which is standard */
};

static void csr1212_fill_cache(struct csr1212_csr_rom_cache *cache)
{
        struct csr1212_keyval *kv, *nkv;
        struct csr1212_keyval_img *kvi;

        for (kv = cache->layout_head;
             kv != cache->layout_tail->next;
             kv = nkv) {
                kvi = (struct csr1212_keyval_img *)(cache->data +
                                bytes_to_quads(kv->offset - cache->offset));
                switch (kv->key.type) {
                default:
                case CSR1212_KV_TYPE_IMMEDIATE:
                case CSR1212_KV_TYPE_CSR_OFFSET:
                        /* Should never get here */
                        WARN_ON(1);
                        break;

                case CSR1212_KV_TYPE_LEAF:
                        /* Don't copy over Extended ROM areas, they are
                         * already filled out! */
                        if (kv->key.id != CSR1212_KV_ID_EXTENDED_ROM)
                                memcpy(kvi->data, kv->value.leaf.data,
                                       quads_to_bytes(kv->value.leaf.len));

                        kvi->length = cpu_to_be16(kv->value.leaf.len);
                        kvi->crc = csr1212_crc16(kvi->data, kv->value.leaf.len);
                        break;

                case CSR1212_KV_TYPE_DIRECTORY:
                        csr1212_generate_tree_subdir(kv, kvi->data);

                        kvi->length = cpu_to_be16(kv->value.directory.len);
                        kvi->crc = csr1212_crc16(kvi->data,
                                                 kv->value.directory.len);
                        break;
                }

                nkv = kv->next;
                if (kv->prev)
                        kv->prev->next = NULL;
                if (kv->next)
                        kv->next->prev = NULL;
                kv->prev = NULL;
                kv->next = NULL;
        }
}

/* This size is arbitrarily chosen.
 * The struct overhead is subtracted for more economic allocations. */
#define CSR1212_EXTENDED_ROM_SIZE (2048 - sizeof(struct csr1212_csr_rom_cache))

int csr1212_generate_csr_image(struct csr1212_csr *csr)
{
        struct csr1212_bus_info_block_img *bi;
        struct csr1212_csr_rom_cache *cache;
        struct csr1212_keyval *kv;
        size_t agg_size;
        int ret;
        int init_offset;

        BUG_ON(!csr);

        cache = csr->cache_head;

        bi = (struct csr1212_bus_info_block_img*)cache->data;

        bi->length = bytes_to_quads(csr->bus_info_len) - 1;
        bi->crc_length = bi->length;
        bi->crc = csr1212_crc16(bi->data, bi->crc_length);

        csr->root_kv->next = NULL;
        csr->root_kv->prev = NULL;

        agg_size = csr1212_generate_layout_order(csr->root_kv);

        init_offset = csr->bus_info_len;

        for (kv = csr->root_kv, cache = csr->cache_head;
             kv;
             cache = cache->next) {
                if (!cache) {
                        /* Estimate approximate number of additional cache
                         * regions needed (it assumes that the cache holding
                         * the first 1K Config ROM space always exists). */
                        int est_c = agg_size / (CSR1212_EXTENDED_ROM_SIZE -
                                                (2 * sizeof(u32))) + 1;

                        /* Add additional cache regions, extras will be
                         * removed later */
                        for (; est_c; est_c--) {
                                ret = csr1212_append_new_cache(csr,
                                                CSR1212_EXTENDED_ROM_SIZE);
                                if (ret != CSR1212_SUCCESS)
                                        return ret;
                        }
                        /* Need to re-layout for additional cache regions */
                        agg_size = csr1212_generate_layout_order(csr->root_kv);
                        kv = csr->root_kv;
                        cache = csr->cache_head;
                        init_offset = csr->bus_info_len;
                }
                kv = csr1212_generate_positions(cache, kv, init_offset);
                agg_size -= cache->len;
                init_offset = sizeof(u32);
        }

        /* Remove unused, excess cache regions */
        while (cache) {
                struct csr1212_csr_rom_cache *oc = cache;

                cache = cache->next;
                csr1212_remove_cache(csr, oc);
        }

        /* Go through the list backward so that when done, the correct CRC
         * will be calculated for the Extended ROM areas. */
        for (cache = csr->cache_tail; cache; cache = cache->prev) {
                /* Only Extended ROM caches should have this set. */
                if (cache->ext_rom) {
                        int leaf_size;

                        /* Make sure the Extended ROM leaf is a multiple of
                         * max_rom in size. */

                        BUG_ON(csr->max_rom < 1);
                        leaf_size = (cache->len + (csr->max_rom - 1)) &
                                ~(csr->max_rom - 1);

                        /* Zero out the unused ROM region */
                        memset(cache->data + bytes_to_quads(cache->len), 0x00,
                               leaf_size - cache->len);

                        /* Subtract leaf header */
                        leaf_size -= sizeof(u32);

                        /* Update the Extended ROM leaf length */
                        cache->ext_rom->value.leaf.len =
                                bytes_to_quads(leaf_size);
                } else {
                        /* Zero out the unused ROM region */
                        memset(cache->data + bytes_to_quads(cache->len), 0x00,
                               cache->size - cache->len);
                }

                /* Copy the data into the cache buffer */
                csr1212_fill_cache(cache);

                if (cache != csr->cache_head) {
                        /* Set the length and CRC of the extended ROM. */
                        struct csr1212_keyval_img *kvi =
                                (struct csr1212_keyval_img*)cache->data;
                        u16 len = bytes_to_quads(cache->len) - 1;

                        kvi->length = cpu_to_be16(len);
                        kvi->crc = csr1212_crc16(kvi->data, len);
                }
        }

        return CSR1212_SUCCESS;
}

int csr1212_read(struct csr1212_csr *csr, u32 offset, void *buffer, u32 len)
{
        struct csr1212_csr_rom_cache *cache;

        for (cache = csr->cache_head; cache; cache = cache->next)
                if (offset >= cache->offset &&
                    (offset + len) <= (cache->offset + cache->size)) {
                        memcpy(buffer, &cache->data[
                                        bytes_to_quads(offset - cache->offset)],
                               len);
                        return CSR1212_SUCCESS;
                }

        return -ENOENT;
}

/*
 * Apparently there are many different wrong implementations of the CRC
 * algorithm.  We don't fail, we just warn... approximately once per GUID.
 */
static void
csr1212_check_crc(const u32 *buffer, size_t length, u16 crc, __be32 *guid)
{
        static u64 last_bad_eui64;
        u64 eui64 = ((u64)be32_to_cpu(guid[0]) << 32) | be32_to_cpu(guid[1]);

        if (csr1212_crc16(buffer, length) == crc ||
            csr1212_msft_crc16(buffer, length) == crc ||
            eui64 == last_bad_eui64)
                return;

        printk(KERN_DEBUG "ieee1394: config ROM CRC error\n");
        last_bad_eui64 = eui64;
}

/* Parse a chunk of data as a Config ROM */

static int csr1212_parse_bus_info_block(struct csr1212_csr *csr)
{
        struct csr1212_bus_info_block_img *bi;
        struct csr1212_cache_region *cr;
        int i;
        int ret;

        for (i = 0; i < csr->bus_info_len; i += sizeof(u32)) {
                ret = csr->ops->bus_read(csr, CSR1212_CONFIG_ROM_SPACE_BASE + i,
                                &csr->cache_head->data[bytes_to_quads(i)],
                                csr->private);
                if (ret != CSR1212_SUCCESS)
                        return ret;

                /* check ROM header's info_length */
                if (i == 0 &&
                    be32_to_cpu(csr->cache_head->data[0]) >> 24 !=
                    bytes_to_quads(csr->bus_info_len) - 1)
                        return -EINVAL;
        }

        bi = (struct csr1212_bus_info_block_img*)csr->cache_head->data;
        csr->crc_len = quads_to_bytes(bi->crc_length);

        /* IEEE 1212 recommends that crc_len be equal to bus_info_len, but that
         * is not always the case, so read the rest of the crc area 1 quadlet at
         * a time. */
        for (i = csr->bus_info_len; i <= csr->crc_len; i += sizeof(u32)) {
                ret = csr->ops->bus_read(csr, CSR1212_CONFIG_ROM_SPACE_BASE + i,
                                &csr->cache_head->data[bytes_to_quads(i)],
                                csr->private);
                if (ret != CSR1212_SUCCESS)
                        return ret;
        }

        csr1212_check_crc(bi->data, bi->crc_length, bi->crc,
                          &csr->bus_info_data[3]);

        cr = CSR1212_MALLOC(sizeof(*cr));
        if (!cr)
                return -ENOMEM;

        cr->next = NULL;
        cr->prev = NULL;
        cr->offset_start = 0;
        cr->offset_end = csr->crc_len + 4;

        csr->cache_head->filled_head = cr;
        csr->cache_head->filled_tail = cr;

        return CSR1212_SUCCESS;
}

#define CSR1212_KV_KEY(q)       (be32_to_cpu(q) >> CSR1212_KV_KEY_SHIFT)
#define CSR1212_KV_KEY_TYPE(q)  (CSR1212_KV_KEY(q) >> CSR1212_KV_KEY_TYPE_SHIFT)
#define CSR1212_KV_KEY_ID(q)    (CSR1212_KV_KEY(q) & CSR1212_KV_KEY_ID_MASK)
#define CSR1212_KV_VAL_MASK     0xffffff
#define CSR1212_KV_VAL(q)       (be32_to_cpu(q) & CSR1212_KV_VAL_MASK)

static int
csr1212_parse_dir_entry(struct csr1212_keyval *dir, u32 ki, u32 kv_pos)
{
        int ret = CSR1212_SUCCESS;
        struct csr1212_keyval *k = NULL;
        u32 offset;
        bool keep_keyval = true;

        switch (CSR1212_KV_KEY_TYPE(ki)) {
        case CSR1212_KV_TYPE_IMMEDIATE:
                k = csr1212_new_immediate(CSR1212_KV_KEY_ID(ki),
                                          CSR1212_KV_VAL(ki));
                if (!k) {
                        ret = -ENOMEM;
                        goto out;
                }
                /* Don't keep local reference when parsing. */
                keep_keyval = false;
                break;

        case CSR1212_KV_TYPE_CSR_OFFSET:
                k = csr1212_new_csr_offset(CSR1212_KV_KEY_ID(ki),
                                           CSR1212_KV_VAL(ki));
                if (!k) {
                        ret = -ENOMEM;
                        goto out;
                }
                /* Don't keep local reference when parsing. */
                keep_keyval = false;
                break;

        default:
                /* Compute the offset from 0xffff f000 0000. */
                offset = quads_to_bytes(CSR1212_KV_VAL(ki)) + kv_pos;
                if (offset == kv_pos) {
                        /* Uh-oh.  Can't have a relative offset of 0 for Leaves
                         * or Directories.  The Config ROM image is most likely
                         * messed up, so we'll just abort here. */
                        ret = -EIO;
                        goto out;
                }

                k = csr1212_find_keyval_offset(dir, offset);

                if (k)
                        break;          /* Found it. */

                if (CSR1212_KV_KEY_TYPE(ki) == CSR1212_KV_TYPE_DIRECTORY)
                        k = csr1212_new_directory(CSR1212_KV_KEY_ID(ki));
                else
                        k = csr1212_new_leaf(CSR1212_KV_KEY_ID(ki), NULL, 0);

                if (!k) {
                        ret = -ENOMEM;
                        goto out;
                }
                /* Don't keep local reference when parsing. */
                keep_keyval = false;
                /* Contents not read yet so it's not valid. */
                k->valid = 0;
                k->offset = offset;

                k->prev = dir;
                k->next = dir->next;
                dir->next->prev = k;
                dir->next = k;
        }
        ret = __csr1212_attach_keyval_to_directory(dir, k, keep_keyval);
out:
        if (ret != CSR1212_SUCCESS && k != NULL)
                free_keyval(k);
        return ret;
}

int csr1212_parse_keyval(struct csr1212_keyval *kv,
                         struct csr1212_csr_rom_cache *cache)
{
        struct csr1212_keyval_img *kvi;
        int i;
        int ret = CSR1212_SUCCESS;
        int kvi_len;

        kvi = (struct csr1212_keyval_img*)
                &cache->data[bytes_to_quads(kv->offset - cache->offset)];
        kvi_len = be16_to_cpu(kvi->length);

        /* GUID is wrong in here in case of extended ROM.  We don't care. */
        csr1212_check_crc(kvi->data, kvi_len, kvi->crc, &cache->data[3]);

        switch (kv->key.type) {
        case CSR1212_KV_TYPE_DIRECTORY:
                for (i = 0; i < kvi_len; i++) {
                        u32 ki = kvi->data[i];

                        /* Some devices put null entries in their unit
                         * directories.  If we come across such an entry,
                         * then skip it. */
                        if (ki == 0x0)
                                continue;
                        ret = csr1212_parse_dir_entry(kv, ki,
                                        kv->offset + quads_to_bytes(i + 1));
                }
                kv->value.directory.len = kvi_len;
                break;

        case CSR1212_KV_TYPE_LEAF:
                if (kv->key.id != CSR1212_KV_ID_EXTENDED_ROM) {
                        size_t size = quads_to_bytes(kvi_len);

                        kv->value.leaf.data = CSR1212_MALLOC(size);
                        if (!kv->value.leaf.data) {
                                ret = -ENOMEM;
                                goto out;
                        }

                        kv->value.leaf.len = kvi_len;
                        memcpy(kv->value.leaf.data, kvi->data, size);
                }
                break;
        }

        kv->valid = 1;
out:
        return ret;
}

static int
csr1212_read_keyval(struct csr1212_csr *csr, struct csr1212_keyval *kv)
{
        struct csr1212_cache_region *cr, *ncr, *newcr = NULL;
        struct csr1212_keyval_img *kvi = NULL;
        struct csr1212_csr_rom_cache *cache;
        int cache_index;
        u64 addr;
        u32 *cache_ptr;
        u16 kv_len = 0;

        BUG_ON(!csr || !kv || csr->max_rom < 1);

        /* First find which cache the data should be in (or go in if not read
         * yet). */
        for (cache = csr->cache_head; cache; cache = cache->next)
                if (kv->offset >= cache->offset &&
                    kv->offset < (cache->offset + cache->size))
                        break;

        if (!cache) {
                u32 q, cache_size;

                /* Only create a new cache for Extended ROM leaves. */
                if (kv->key.id != CSR1212_KV_ID_EXTENDED_ROM)
                        return -EINVAL;

                if (csr->ops->bus_read(csr,
                                       CSR1212_REGISTER_SPACE_BASE + kv->offset,
                                       &q, csr->private))
                        return -EIO;

                kv->value.leaf.len = be32_to_cpu(q) >> 16;

                cache_size = (quads_to_bytes(kv->value.leaf.len + 1) +
                              (csr->max_rom - 1)) & ~(csr->max_rom - 1);

                cache = csr1212_rom_cache_malloc(kv->offset, cache_size);
                if (!cache)
                        return -ENOMEM;

                kv->value.leaf.data = &cache->data[1];
                csr->cache_tail->next = cache;
                cache->prev = csr->cache_tail;
                cache->next = NULL;
                csr->cache_tail = cache;
                cache->filled_head =
                        CSR1212_MALLOC(sizeof(*cache->filled_head));
                if (!cache->filled_head)
                        return -ENOMEM;

                cache->filled_head->offset_start = 0;
                cache->filled_head->offset_end = sizeof(u32);
                cache->filled_tail = cache->filled_head;
                cache->filled_head->next = NULL;
                cache->filled_head->prev = NULL;
                cache->data[0] = q;

                /* Don't read the entire extended ROM now.  Pieces of it will
                 * be read when entries inside it are read. */
                return csr1212_parse_keyval(kv, cache);
        }

        cache_index = kv->offset - cache->offset;

        /* Now seach read portions of the cache to see if it is there. */
        for (cr = cache->filled_head; cr; cr = cr->next) {
                if (cache_index < cr->offset_start) {
                        newcr = CSR1212_MALLOC(sizeof(*newcr));
                        if (!newcr)
                                return -ENOMEM;

                        newcr->offset_start = cache_index & ~(csr->max_rom - 1);
                        newcr->offset_end = newcr->offset_start;
                        newcr->next = cr;
                        newcr->prev = cr->prev;
                        cr->prev = newcr;
                        cr = newcr;
                        break;
                } else if ((cache_index >= cr->offset_start) &&
                           (cache_index < cr->offset_end)) {
                        kvi = (struct csr1212_keyval_img*)
                                (&cache->data[bytes_to_quads(cache_index)]);
                        kv_len = quads_to_bytes(be16_to_cpu(kvi->length) + 1);
                        break;
                } else if (cache_index == cr->offset_end) {
                        break;
                }
        }

        if (!cr) {
                cr = cache->filled_tail;
                newcr = CSR1212_MALLOC(sizeof(*newcr));
                if (!newcr)
                        return -ENOMEM;

                newcr->offset_start = cache_index & ~(csr->max_rom - 1);
                newcr->offset_end = newcr->offset_start;
                newcr->prev = cr;
                newcr->next = cr->next;
                cr->next = newcr;
                cr = newcr;
                cache->filled_tail = newcr;
        }

        while(!kvi || cr->offset_end < cache_index + kv_len) {
                cache_ptr = &cache->data[bytes_to_quads(cr->offset_end &
                                                        ~(csr->max_rom - 1))];

                addr = (CSR1212_CSR_ARCH_REG_SPACE_BASE + cache->offset +
                        cr->offset_end) & ~(csr->max_rom - 1);

                if (csr->ops->bus_read(csr, addr, cache_ptr, csr->private))
                        return -EIO;

                cr->offset_end += csr->max_rom - (cr->offset_end &
                                                  (csr->max_rom - 1));

                if (!kvi && (cr->offset_end > cache_index)) {
                        kvi = (struct csr1212_keyval_img*)
                                (&cache->data[bytes_to_quads(cache_index)]);
                        kv_len = quads_to_bytes(be16_to_cpu(kvi->length) + 1);
                }

                if ((kv_len + (kv->offset - cache->offset)) > cache->size) {
                        /* The Leaf or Directory claims its length extends
                         * beyond the ConfigROM image region and thus beyond the
                         * end of our cache region.  Therefore, we abort now
                         * rather than seg faulting later. */
                        return -EIO;
                }

                ncr = cr->next;

                if (ncr && (cr->offset_end >= ncr->offset_start)) {
                        /* consolidate region entries */
                        ncr->offset_start = cr->offset_start;

                        if (cr->prev)
                                cr->prev->next = cr->next;
                        ncr->prev = cr->prev;
                        if (cache->filled_head == cr)
                                cache->filled_head = ncr;
                        CSR1212_FREE(cr);
                        cr = ncr;
                }
        }

        return csr1212_parse_keyval(kv, cache);
}

struct csr1212_keyval *
csr1212_get_keyval(struct csr1212_csr *csr, struct csr1212_keyval *kv)
{
        if (!kv)
                return NULL;
        if (!kv->valid)
                if (csr1212_read_keyval(csr, kv) != CSR1212_SUCCESS)
                        return NULL;
        return kv;
}

int csr1212_parse_csr(struct csr1212_csr *csr)
{
        struct csr1212_dentry *dentry;
        int ret;

        BUG_ON(!csr || !csr->ops || !csr->ops->bus_read);

        ret = csr1212_parse_bus_info_block(csr);
        if (ret != CSR1212_SUCCESS)
                return ret;

        /*
         * There has been a buggy firmware with bus_info_block.max_rom > 0
         * spotted which actually only supported quadlet read requests to the
         * config ROM.  Therefore read everything quadlet by quadlet regardless
         * of what the bus info block says.
         */
        csr->max_rom = 4;

        csr->cache_head->layout_head = csr->root_kv;
        csr->cache_head->layout_tail = csr->root_kv;

        csr->root_kv->offset = (CSR1212_CONFIG_ROM_SPACE_BASE & 0xffff) +
                csr->bus_info_len;

        csr->root_kv->valid = 0;
        csr->root_kv->next = csr->root_kv;
        csr->root_kv->prev = csr->root_kv;
        ret = csr1212_read_keyval(csr, csr->root_kv);
        if (ret != CSR1212_SUCCESS)
                return ret;

        /* Scan through the Root directory finding all extended ROM regions
         * and make cache regions for them */
        for (dentry = csr->root_kv->value.directory.dentries_head;
             dentry; dentry = dentry->next) {
                if (dentry->kv->key.id == CSR1212_KV_ID_EXTENDED_ROM &&
                        !dentry->kv->valid) {
                        ret = csr1212_read_keyval(csr, dentry->kv);
                        if (ret != CSR1212_SUCCESS)
                                return ret;
                }
        }

        return CSR1212_SUCCESS;
}