// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  fw_tables.c - Parsing support for ACPI and ACPI-like tables provided by
 *                platform or device firmware
 *
 *  Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *  Copyright (C) 2023 Intel Corp.
 */
#include <linux/errno.h>
#include <linux/acpi.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/fw_table.h>

enum acpi_subtable_type {
        ACPI_SUBTABLE_COMMON,
        ACPI_SUBTABLE_HMAT,
        ACPI_SUBTABLE_PRMT,
        ACPI_SUBTABLE_CEDT,
        CDAT_SUBTABLE,
};

struct acpi_subtable_entry {
        union acpi_subtable_headers *hdr;
        enum acpi_subtable_type type;
};

static unsigned long __init_or_fwtbl_lib
acpi_get_entry_type(struct acpi_subtable_entry *entry)
{
        switch (entry->type) {
        case ACPI_SUBTABLE_COMMON:
                return entry->hdr->common.type;
        case ACPI_SUBTABLE_HMAT:
                return entry->hdr->hmat.type;
        case ACPI_SUBTABLE_PRMT:
                return 0;
        case ACPI_SUBTABLE_CEDT:
                return entry->hdr->cedt.type;
        case CDAT_SUBTABLE:
                return entry->hdr->cdat.type;
        }
        return 0;
}

static unsigned long __init_or_fwtbl_lib
acpi_get_entry_length(struct acpi_subtable_entry *entry)
{
        switch (entry->type) {
        case ACPI_SUBTABLE_COMMON:
                return entry->hdr->common.length;
        case ACPI_SUBTABLE_HMAT:
                return entry->hdr->hmat.length;
        case ACPI_SUBTABLE_PRMT:
                return entry->hdr->prmt.length;
        case ACPI_SUBTABLE_CEDT:
                return entry->hdr->cedt.length;
        case CDAT_SUBTABLE: {
                __le16 length = (__force __le16)entry->hdr->cdat.length;

                return le16_to_cpu(length);
        }
        }
        return 0;
}

static unsigned long __init_or_fwtbl_lib
acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
{
        switch (entry->type) {
        case ACPI_SUBTABLE_COMMON:
                return sizeof(entry->hdr->common);
        case ACPI_SUBTABLE_HMAT:
                return sizeof(entry->hdr->hmat);
        case ACPI_SUBTABLE_PRMT:
                return sizeof(entry->hdr->prmt);
        case ACPI_SUBTABLE_CEDT:
                return sizeof(entry->hdr->cedt);
        case CDAT_SUBTABLE:
                return sizeof(entry->hdr->cdat);
        }
        return 0;
}

static enum acpi_subtable_type __init_or_fwtbl_lib
acpi_get_subtable_type(char *id)
{
        if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
                return ACPI_SUBTABLE_HMAT;
        if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
                return ACPI_SUBTABLE_PRMT;
        if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
                return ACPI_SUBTABLE_CEDT;
        if (strncmp(id, ACPI_SIG_CDAT, 4) == 0)
                return CDAT_SUBTABLE;
        return ACPI_SUBTABLE_COMMON;
}

static unsigned long __init_or_fwtbl_lib
acpi_table_get_length(enum acpi_subtable_type type,
                      union fw_table_header *header)
{
        if (type == CDAT_SUBTABLE) {
                __le32 length = (__force __le32)header->cdat.length;

                return le32_to_cpu(length);
        }

        return header->acpi.length;
}

static __init_or_fwtbl_lib int call_handler(struct acpi_subtable_proc *proc,
                                            union acpi_subtable_headers *hdr,
                                            unsigned long end)
{
        if (proc->handler)
                return proc->handler(hdr, end);
        if (proc->handler_arg)
                return proc->handler_arg(hdr, proc->arg, end);
        return -EINVAL;
}

/**
 * acpi_parse_entries_array - for each proc_num find a suitable subtable
 *
 * @id: table id (for debugging purposes)
 * @table_size: size of the root table
 * @max_length: maximum size of the table (ignore if 0)
 * @table_header: where does the table start?
 * @proc: array of acpi_subtable_proc struct containing entry id
 *        and associated handler with it
 * @proc_num: how big proc is?
 * @max_entries: how many entries can we process?
 *
 * For each proc_num find a subtable with proc->id and run proc->handler
 * on it. Assumption is that there's only single handler for particular
 * entry id.
 *
 * The table_size is not the size of the complete ACPI table (the length
 * field in the header struct), but only the size of the root table; i.e.,
 * the offset from the very first byte of the complete ACPI table, to the
 * first byte of the very first subtable.
 *
 * On success returns sum of all matching entries for all proc handlers.
 * Otherwise, -ENODEV or -EINVAL is returned.
 */
int __init_or_fwtbl_lib
acpi_parse_entries_array(char *id, unsigned long table_size,
                         union fw_table_header *table_header,
                         unsigned long max_length,
                         struct acpi_subtable_proc *proc,
                         int proc_num, unsigned int max_entries)
{
        unsigned long table_len, table_end, subtable_len, entry_len;
        struct acpi_subtable_entry entry;
        enum acpi_subtable_type type;
        int count = 0;
        int i;

        type = acpi_get_subtable_type(id);
        table_len = acpi_table_get_length(type, table_header);
        if (max_length && max_length < table_len)
                table_len = max_length;
        table_end = (unsigned long)table_header + table_len;

        /* Parse all entries looking for a match. */

        entry.type = type;
        entry.hdr = (union acpi_subtable_headers *)
            ((unsigned long)table_header + table_size);
        subtable_len = acpi_get_subtable_header_length(&entry);

        while (((unsigned long)entry.hdr) + subtable_len < table_end) {
                for (i = 0; i < proc_num; i++) {
                        if (acpi_get_entry_type(&entry) != proc[i].id)
                                continue;

                        if (!max_entries || count < max_entries)
                                if (call_handler(&proc[i], entry.hdr, table_end))
                                        return -EINVAL;

                        proc[i].count++;
                        count++;
                        break;
                }

                /*
                 * If entry->length is 0, break from this loop to avoid
                 * infinite loop.
                 */
                entry_len = acpi_get_entry_length(&entry);
                if (entry_len == 0) {
                        pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
                        return -EINVAL;
                }

                entry.hdr = (union acpi_subtable_headers *)
                    ((unsigned long)entry.hdr + entry_len);
        }

        if (max_entries && count > max_entries) {
                pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n",
                        id, proc->id, count - max_entries, count);
        }

        return count;
}

int __init_or_fwtbl_lib
cdat_table_parse(enum acpi_cdat_type type,
                 acpi_tbl_entry_handler_arg handler_arg,
                 void *arg,
                 struct acpi_table_cdat *table_header,
                 unsigned long length)
{
        struct acpi_subtable_proc proc = {
                .id             = type,
                .handler_arg    = handler_arg,
                .arg            = arg,
        };

        if (!table_header)
                return -EINVAL;

        return acpi_parse_entries_array(ACPI_SIG_CDAT,
                                        sizeof(struct acpi_table_cdat),
                                        (union fw_table_header *)table_header,
                                        length, &proc, 1, 0);
}
EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse);