/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2016-2018, The Linux Foundation. All rights reserved. */

#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/of_reserved_mem.h>
#include <linux/platform_device.h>
#include <linux/types.h>

#include <soc/qcom/cmd-db.h>

#define NUM_PRIORITY            2
#define MAX_SLV_ID              8
#define SLAVE_ID_MASK           0x7
#define SLAVE_ID_SHIFT          16

/**
 * struct entry_header: header for each entry in cmddb
 *
 * @id: resource's identifier
 * @priority: unused
 * @addr: the address of the resource
 * @len: length of the data
 * @offset: offset from :@data_offset, start of the data
 */
struct entry_header {
        u8 id[8];
        __le32 priority[NUM_PRIORITY];
        __le32 addr;
        __le16 len;
        __le16 offset;
};

/**
 * struct rsc_hdr: resource header information
 *
 * @slv_id: id for the resource
 * @header_offset: entry's header at offset from the end of the cmd_db_header
 * @data_offset: entry's data at offset from the end of the cmd_db_header
 * @cnt: number of entries for HW type
 * @version: MSB is major, LSB is minor
 * @reserved: reserved for future use.
 */
struct rsc_hdr {
        __le16 slv_id;
        __le16 header_offset;
        __le16 data_offset;
        __le16 cnt;
        __le16 version;
        __le16 reserved[3];
};

/**
 * struct cmd_db_header: The DB header information
 *
 * @version: The cmd db version
 * @magic: constant expected in the database
 * @header: array of resources
 * @checksum: checksum for the header. Unused.
 * @reserved: reserved memory
 * @data: driver specific data
 */
struct cmd_db_header {
        __le32 version;
        u8 magic[4];
        struct rsc_hdr header[MAX_SLV_ID];
        __le32 checksum;
        __le32 reserved;
        u8 data[];
};

/**
 * DOC: Description of the Command DB database.
 *
 * At the start of the command DB memory is the cmd_db_header structure.
 * The cmd_db_header holds the version, checksum, magic key as well as an
 * array for header for each slave (depicted by the rsc_header). Each h/w
 * based accelerator is a 'slave' (shared resource) and has slave id indicating
 * the type of accelerator. The rsc_header is the header for such individual
 * slaves of a given type. The entries for each of these slaves begin at the
 * rsc_hdr.header_offset. In addition each slave could have auxiliary data
 * that may be needed by the driver. The data for the slave starts at the
 * entry_header.offset to the location pointed to by the rsc_hdr.data_offset.
 *
 * Drivers have a stringified key to a slave/resource. They can query the slave
 * information and get the slave id and the auxiliary data and the length of the
 * data. Using this information, they can format the request to be sent to the
 * h/w accelerator and request a resource state.
 */

static const u8 CMD_DB_MAGIC[] = { 0xdb, 0x30, 0x03, 0x0c };

static bool cmd_db_magic_matches(const struct cmd_db_header *header)
{
        const u8 *magic = header->magic;

        return memcmp(magic, CMD_DB_MAGIC, ARRAY_SIZE(CMD_DB_MAGIC)) == 0;
}

static struct cmd_db_header *cmd_db_header;

static inline const void *rsc_to_entry_header(const struct rsc_hdr *hdr)
{
        u16 offset = le16_to_cpu(hdr->header_offset);

        return cmd_db_header->data + offset;
}

static inline void *
rsc_offset(const struct rsc_hdr *hdr, const struct entry_header *ent)
{
        u16 offset = le16_to_cpu(hdr->data_offset);
        u16 loffset = le16_to_cpu(ent->offset);

        return cmd_db_header->data + offset + loffset;
}

/**
 * cmd_db_ready - Indicates if command DB is available
 *
 * Return: 0 on success, errno otherwise
 */
int cmd_db_ready(void)
{
        if (cmd_db_header == NULL)
                return -EPROBE_DEFER;
        else if (!cmd_db_magic_matches(cmd_db_header))
                return -EINVAL;

        return 0;
}
EXPORT_SYMBOL(cmd_db_ready);

static int cmd_db_get_header(const char *id, const struct entry_header **eh,
                             const struct rsc_hdr **rh)
{
        const struct rsc_hdr *rsc_hdr;
        const struct entry_header *ent;
        int ret, i, j;
        u8 query[8];

        ret = cmd_db_ready();
        if (ret)
                return ret;

        /* Pad out query string to same length as in DB */
        strncpy(query, id, sizeof(query));

        for (i = 0; i < MAX_SLV_ID; i++) {
                rsc_hdr = &cmd_db_header->header[i];
                if (!rsc_hdr->slv_id)
                        break;

                ent = rsc_to_entry_header(rsc_hdr);
                for (j = 0; j < le16_to_cpu(rsc_hdr->cnt); j++, ent++) {
                        if (memcmp(ent->id, query, sizeof(ent->id)) == 0) {
                                if (eh)
                                        *eh = ent;
                                if (rh)
                                        *rh = rsc_hdr;
                                return 0;
                        }
                }
        }

        return -ENODEV;
}

/**
 * cmd_db_read_addr() - Query command db for resource id address.
 *
 * @id: resource id to query for address
 *
 * Return: resource address on success, 0 on error
 *
 * This is used to retrieve resource address based on resource
 * id.
 */
u32 cmd_db_read_addr(const char *id)
{
        int ret;
        const struct entry_header *ent;

        ret = cmd_db_get_header(id, &ent, NULL);

        return ret < 0 ? 0 : le32_to_cpu(ent->addr);
}
EXPORT_SYMBOL(cmd_db_read_addr);

/**
 * cmd_db_read_aux_data() - Query command db for aux data.
 *
 *  @id: Resource to retrieve AUX Data on
 *  @len: size of data buffer returned
 *
 *  Return: pointer to data on success, error pointer otherwise
 */
const void *cmd_db_read_aux_data(const char *id, size_t *len)
{
        int ret;
        const struct entry_header *ent;
        const struct rsc_hdr *rsc_hdr;

        ret = cmd_db_get_header(id, &ent, &rsc_hdr);
        if (ret)
                return ERR_PTR(ret);

        if (len)
                *len = le16_to_cpu(ent->len);

        return rsc_offset(rsc_hdr, ent);
}
EXPORT_SYMBOL(cmd_db_read_aux_data);

/**
 * cmd_db_read_slave_id - Get the slave ID for a given resource address
 *
 * @id: Resource id to query the DB for version
 *
 * Return: cmd_db_hw_type enum on success, CMD_DB_HW_INVALID on error
 */
enum cmd_db_hw_type cmd_db_read_slave_id(const char *id)
{
        int ret;
        const struct entry_header *ent;
        u32 addr;

        ret = cmd_db_get_header(id, &ent, NULL);
        if (ret < 0)
                return CMD_DB_HW_INVALID;

        addr = le32_to_cpu(ent->addr);
        return (addr >> SLAVE_ID_SHIFT) & SLAVE_ID_MASK;
}
EXPORT_SYMBOL(cmd_db_read_slave_id);

static int cmd_db_dev_probe(struct platform_device *pdev)
{
        struct reserved_mem *rmem;
        int ret = 0;

        rmem = of_reserved_mem_lookup(pdev->dev.of_node);
        if (!rmem) {
                dev_err(&pdev->dev, "failed to acquire memory region\n");
                return -EINVAL;
        }

        cmd_db_header = memremap(rmem->base, rmem->size, MEMREMAP_WB);
        if (!cmd_db_header) {
                ret = -ENOMEM;
                cmd_db_header = NULL;
                return ret;
        }

        if (!cmd_db_magic_matches(cmd_db_header)) {
                dev_err(&pdev->dev, "Invalid Command DB Magic\n");
                return -EINVAL;
        }

        return 0;
}

static const struct of_device_id cmd_db_match_table[] = {
        { .compatible = "qcom,cmd-db" },
        { },
};

static struct platform_driver cmd_db_dev_driver = {
        .probe  = cmd_db_dev_probe,
        .driver = {
                   .name = "cmd-db",
                   .of_match_table = cmd_db_match_table,
        },
};

static int __init cmd_db_device_init(void)
{
        return platform_driver_register(&cmd_db_dev_driver);
}
arch_initcall(cmd_db_device_init);