// SPDX-License-Identifier: GPL-2.0
/*
 * Greybus manifest parsing
 *
 * Copyright 2014-2015 Google Inc.
 * Copyright 2014-2015 Linaro Ltd.
 */

#include <linux/greybus.h>

static const char *get_descriptor_type_string(u8 type)
{
        switch (type) {
        case GREYBUS_TYPE_INVALID:
                return "invalid";
        case GREYBUS_TYPE_STRING:
                return "string";
        case GREYBUS_TYPE_INTERFACE:
                return "interface";
        case GREYBUS_TYPE_CPORT:
                return "cport";
        case GREYBUS_TYPE_BUNDLE:
                return "bundle";
        default:
                WARN_ON(1);
                return "unknown";
        }
}

/*
 * We scan the manifest once to identify where all the descriptors
 * are.  The result is a list of these manifest_desc structures.  We
 * then pick through them for what we're looking for (starting with
 * the interface descriptor).  As each is processed we remove it from
 * the list.  When we're done the list should (probably) be empty.
 */
struct manifest_desc {
        struct list_head                links;

        size_t                          size;
        void                            *data;
        enum greybus_descriptor_type    type;
};

static void release_manifest_descriptor(struct manifest_desc *descriptor)
{
        list_del(&descriptor->links);
        kfree(descriptor);
}

static void release_manifest_descriptors(struct gb_interface *intf)
{
        struct manifest_desc *descriptor;
        struct manifest_desc *next;

        list_for_each_entry_safe(descriptor, next, &intf->manifest_descs, links)
                release_manifest_descriptor(descriptor);
}

static void release_cport_descriptors(struct list_head *head, u8 bundle_id)
{
        struct manifest_desc *desc, *tmp;
        struct greybus_descriptor_cport *desc_cport;

        list_for_each_entry_safe(desc, tmp, head, links) {
                desc_cport = desc->data;

                if (desc->type != GREYBUS_TYPE_CPORT)
                        continue;

                if (desc_cport->bundle == bundle_id)
                        release_manifest_descriptor(desc);
        }
}

static struct manifest_desc *get_next_bundle_desc(struct gb_interface *intf)
{
        struct manifest_desc *descriptor;
        struct manifest_desc *next;

        list_for_each_entry_safe(descriptor, next, &intf->manifest_descs, links)
                if (descriptor->type == GREYBUS_TYPE_BUNDLE)
                        return descriptor;

        return NULL;
}

/*
 * Validate the given descriptor.  Its reported size must fit within
 * the number of bytes remaining, and it must have a recognized
 * type.  Check that the reported size is at least as big as what
 * we expect to see.  (It could be bigger, perhaps for a new version
 * of the format.)
 *
 * Returns the (non-zero) number of bytes consumed by the descriptor,
 * or a negative errno.
 */
static int identify_descriptor(struct gb_interface *intf,
                               struct greybus_descriptor *desc, size_t size)
{
        struct greybus_descriptor_header *desc_header = &desc->header;
        struct manifest_desc *descriptor;
        size_t desc_size;
        size_t expected_size;

        if (size < sizeof(*desc_header)) {
                dev_err(&intf->dev, "manifest too small (%zu < %zu)\n", size,
                        sizeof(*desc_header));
                return -EINVAL;         /* Must at least have header */
        }

        desc_size = le16_to_cpu(desc_header->size);
        if (desc_size > size) {
                dev_err(&intf->dev, "descriptor too big (%zu > %zu)\n",
                        desc_size, size);
                return -EINVAL;
        }

        /* Descriptor needs to at least have a header */
        expected_size = sizeof(*desc_header);

        switch (desc_header->type) {
        case GREYBUS_TYPE_STRING:
                expected_size += sizeof(struct greybus_descriptor_string);
                expected_size += desc->string.length;

                /* String descriptors are padded to 4 byte boundaries */
                expected_size = ALIGN(expected_size, 4);
                break;
        case GREYBUS_TYPE_INTERFACE:
                expected_size += sizeof(struct greybus_descriptor_interface);
                break;
        case GREYBUS_TYPE_BUNDLE:
                expected_size += sizeof(struct greybus_descriptor_bundle);
                break;
        case GREYBUS_TYPE_CPORT:
                expected_size += sizeof(struct greybus_descriptor_cport);
                break;
        case GREYBUS_TYPE_INVALID:
        default:
                dev_err(&intf->dev, "invalid descriptor type (%u)\n",
                        desc_header->type);
                return -EINVAL;
        }

        if (desc_size < expected_size) {
                dev_err(&intf->dev, "%s descriptor too small (%zu < %zu)\n",
                        get_descriptor_type_string(desc_header->type),
                        desc_size, expected_size);
                return -EINVAL;
        }

        /* Descriptor bigger than what we expect */
        if (desc_size > expected_size) {
                dev_warn(&intf->dev, "%s descriptor size mismatch (want %zu got %zu)\n",
                         get_descriptor_type_string(desc_header->type),
                         expected_size, desc_size);
        }

        descriptor = kzalloc(sizeof(*descriptor), GFP_KERNEL);
        if (!descriptor)
                return -ENOMEM;

        descriptor->size = desc_size;
        descriptor->data = (char *)desc + sizeof(*desc_header);
        descriptor->type = desc_header->type;
        list_add_tail(&descriptor->links, &intf->manifest_descs);

        /* desc_size is positive and is known to fit in a signed int */

        return desc_size;
}

/*
 * Find the string descriptor having the given id, validate it, and
 * allocate a duplicate copy of it.  The duplicate has an extra byte
 * which guarantees the returned string is NUL-terminated.
 *
 * String index 0 is valid (it represents "no string"), and for
 * that a null pointer is returned.
 *
 * Otherwise returns a pointer to a newly-allocated copy of the
 * descriptor string, or an error-coded pointer on failure.
 */
static char *gb_string_get(struct gb_interface *intf, u8 string_id)
{
        struct greybus_descriptor_string *desc_string;
        struct manifest_desc *descriptor;
        bool found = false;
        char *string;

        /* A zero string id means no string (but no error) */
        if (!string_id)
                return NULL;

        list_for_each_entry(descriptor, &intf->manifest_descs, links) {
                if (descriptor->type != GREYBUS_TYPE_STRING)
                        continue;

                desc_string = descriptor->data;
                if (desc_string->id == string_id) {
                        found = true;
                        break;
                }
        }
        if (!found)
                return ERR_PTR(-ENOENT);

        /* Allocate an extra byte so we can guarantee it's NUL-terminated */
        string = kmemdup(&desc_string->string, desc_string->length + 1,
                         GFP_KERNEL);
        if (!string)
                return ERR_PTR(-ENOMEM);
        string[desc_string->length] = '\0';

        /* Ok we've used this string, so we're done with it */
        release_manifest_descriptor(descriptor);

        return string;
}

/*
 * Find cport descriptors in the manifest associated with the given
 * bundle, and set up data structures for the functions that use
 * them.  Returns the number of cports set up for the bundle, or 0
 * if there is an error.
 */
static u32 gb_manifest_parse_cports(struct gb_bundle *bundle)
{
        struct gb_interface *intf = bundle->intf;
        struct greybus_descriptor_cport *desc_cport;
        struct manifest_desc *desc, *next, *tmp;
        LIST_HEAD(list);
        u8 bundle_id = bundle->id;
        u16 cport_id;
        u32 count = 0;
        int i;

        /* Set up all cport descriptors associated with this bundle */
        list_for_each_entry_safe(desc, next, &intf->manifest_descs, links) {
                if (desc->type != GREYBUS_TYPE_CPORT)
                        continue;

                desc_cport = desc->data;
                if (desc_cport->bundle != bundle_id)
                        continue;

                cport_id = le16_to_cpu(desc_cport->id);
                if (cport_id > CPORT_ID_MAX)
                        goto exit;

                /* Nothing else should have its cport_id as control cport id */
                if (cport_id == GB_CONTROL_CPORT_ID) {
                        dev_err(&bundle->dev, "invalid cport id found (%02u)\n",
                                cport_id);
                        goto exit;
                }

                /*
                 * Found one, move it to our temporary list after checking for
                 * duplicates.
                 */
                list_for_each_entry(tmp, &list, links) {
                        desc_cport = tmp->data;
                        if (cport_id == le16_to_cpu(desc_cport->id)) {
                                dev_err(&bundle->dev,
                                        "duplicate CPort %u found\n", cport_id);
                                goto exit;
                        }
                }
                list_move_tail(&desc->links, &list);
                count++;
        }

        if (!count)
                return 0;

        bundle->cport_desc = kcalloc(count, sizeof(*bundle->cport_desc),
                                     GFP_KERNEL);
        if (!bundle->cport_desc)
                goto exit;

        bundle->num_cports = count;

        i = 0;
        list_for_each_entry_safe(desc, next, &list, links) {
                desc_cport = desc->data;
                memcpy(&bundle->cport_desc[i++], desc_cport,
                       sizeof(*desc_cport));

                /* Release the cport descriptor */
                release_manifest_descriptor(desc);
        }

        return count;
exit:
        release_cport_descriptors(&list, bundle_id);
        /*
         * Free all cports for this bundle to avoid 'excess descriptors'
         * warnings.
         */
        release_cport_descriptors(&intf->manifest_descs, bundle_id);

        return 0;       /* Error; count should also be 0 */
}

/*
 * Find bundle descriptors in the manifest and set up their data
 * structures.  Returns the number of bundles set up for the
 * given interface.
 */
static u32 gb_manifest_parse_bundles(struct gb_interface *intf)
{
        struct manifest_desc *desc;
        struct gb_bundle *bundle;
        struct gb_bundle *bundle_next;
        u32 count = 0;
        u8 bundle_id;
        u8 class;

        while ((desc = get_next_bundle_desc(intf))) {
                struct greybus_descriptor_bundle *desc_bundle;

                /* Found one.  Set up its bundle structure*/
                desc_bundle = desc->data;
                bundle_id = desc_bundle->id;
                class = desc_bundle->class;

                /* Done with this bundle descriptor */
                release_manifest_descriptor(desc);

                /* Ignore any legacy control bundles */
                if (bundle_id == GB_CONTROL_BUNDLE_ID) {
                        dev_dbg(&intf->dev, "%s - ignoring control bundle\n",
                                __func__);
                        release_cport_descriptors(&intf->manifest_descs,
                                                  bundle_id);
                        continue;
                }

                /* Nothing else should have its class set to control class */
                if (class == GREYBUS_CLASS_CONTROL) {
                        dev_err(&intf->dev,
                                "bundle %u cannot use control class\n",
                                bundle_id);
                        goto cleanup;
                }

                bundle = gb_bundle_create(intf, bundle_id, class);
                if (!bundle)
                        goto cleanup;

                /*
                 * Now go set up this bundle's functions and cports.
                 *
                 * A 'bundle' represents a device in greybus. It may require
                 * multiple cports for its functioning. If we fail to setup any
                 * cport of a bundle, we better reject the complete bundle as
                 * the device may not be able to function properly then.
                 *
                 * But, failing to setup a cport of bundle X doesn't mean that
                 * the device corresponding to bundle Y will not work properly.
                 * Bundles should be treated as separate independent devices.
                 *
                 * While parsing manifest for an interface, treat bundles as
                 * separate entities and don't reject entire interface and its
                 * bundles on failing to initialize a cport. But make sure the
                 * bundle which needs the cport, gets destroyed properly.
                 */
                if (!gb_manifest_parse_cports(bundle)) {
                        gb_bundle_destroy(bundle);
                        continue;
                }

                count++;
        }

        return count;
cleanup:
        /* An error occurred; undo any changes we've made */
        list_for_each_entry_safe(bundle, bundle_next, &intf->bundles, links) {
                gb_bundle_destroy(bundle);
                count--;
        }
        return 0;       /* Error; count should also be 0 */
}

static bool gb_manifest_parse_interface(struct gb_interface *intf,
                                        struct manifest_desc *interface_desc)
{
        struct greybus_descriptor_interface *desc_intf = interface_desc->data;
        struct gb_control *control = intf->control;
        char *str;

        /* Handle the strings first--they can fail */
        str = gb_string_get(intf, desc_intf->vendor_stringid);
        if (IS_ERR(str))
                return false;
        control->vendor_string = str;

        str = gb_string_get(intf, desc_intf->product_stringid);
        if (IS_ERR(str))
                goto out_free_vendor_string;
        control->product_string = str;

        /* Assign feature flags communicated via manifest */
        intf->features = desc_intf->features;

        /* Release the interface descriptor, now that we're done with it */
        release_manifest_descriptor(interface_desc);

        /* An interface must have at least one bundle descriptor */
        if (!gb_manifest_parse_bundles(intf)) {
                dev_err(&intf->dev, "manifest bundle descriptors not valid\n");
                goto out_err;
        }

        return true;
out_err:
        kfree(control->product_string);
        control->product_string = NULL;
out_free_vendor_string:
        kfree(control->vendor_string);
        control->vendor_string = NULL;

        return false;
}

/*
 * Parse a buffer containing an interface manifest.
 *
 * If we find anything wrong with the content/format of the buffer
 * we reject it.
 *
 * The first requirement is that the manifest's version is
 * one we can parse.
 *
 * We make an initial pass through the buffer and identify all of
 * the descriptors it contains, keeping track for each its type
 * and the location size of its data in the buffer.
 *
 * Next we scan the descriptors, looking for an interface descriptor;
 * there must be exactly one of those.  When found, we record the
 * information it contains, and then remove that descriptor (and any
 * string descriptors it refers to) from further consideration.
 *
 * After that we look for the interface's bundles--there must be at
 * least one of those.
 *
 * Returns true if parsing was successful, false otherwise.
 */
bool gb_manifest_parse(struct gb_interface *intf, void *data, size_t size)
{
        struct greybus_manifest *manifest;
        struct greybus_manifest_header *header;
        struct greybus_descriptor *desc;
        struct manifest_desc *descriptor;
        struct manifest_desc *interface_desc = NULL;
        u16 manifest_size;
        u32 found = 0;
        bool result;

        /* Manifest descriptor list should be empty here */
        if (WARN_ON(!list_empty(&intf->manifest_descs)))
                return false;

        /* we have to have at _least_ the manifest header */
        if (size < sizeof(*header)) {
                dev_err(&intf->dev, "short manifest (%zu < %zu)\n",
                        size, sizeof(*header));
                return false;
        }

        /* Make sure the size is right */
        manifest = data;
        header = &manifest->header;
        manifest_size = le16_to_cpu(header->size);
        if (manifest_size != size) {
                dev_err(&intf->dev, "manifest size mismatch (%zu != %u)\n",
                        size, manifest_size);
                return false;
        }

        /* Validate major/minor number */
        if (header->version_major > GREYBUS_VERSION_MAJOR) {
                dev_err(&intf->dev, "manifest version too new (%u.%u > %u.%u)\n",
                        header->version_major, header->version_minor,
                        GREYBUS_VERSION_MAJOR, GREYBUS_VERSION_MINOR);
                return false;
        }

        /* OK, find all the descriptors */
        desc = manifest->descriptors;
        size -= sizeof(*header);
        while (size) {
                int desc_size;

                desc_size = identify_descriptor(intf, desc, size);
                if (desc_size < 0) {
                        result = false;
                        goto out;
                }
                desc = (struct greybus_descriptor *)((char *)desc + desc_size);
                size -= desc_size;
        }

        /* There must be a single interface descriptor */
        list_for_each_entry(descriptor, &intf->manifest_descs, links) {
                if (descriptor->type == GREYBUS_TYPE_INTERFACE)
                        if (!found++)
                                interface_desc = descriptor;
        }
        if (found != 1) {
                dev_err(&intf->dev, "manifest must have 1 interface descriptor (%u found)\n",
                        found);
                result = false;
                goto out;
        }

        /* Parse the manifest, starting with the interface descriptor */
        result = gb_manifest_parse_interface(intf, interface_desc);

        /*
         * We really should have no remaining descriptors, but we
         * don't know what newer format manifests might leave.
         */
        if (result && !list_empty(&intf->manifest_descs))
                dev_info(&intf->dev, "excess descriptors in interface manifest\n");
out:
        release_manifest_descriptors(intf);

        return result;
}