// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2022-2023, Ventana Micro Systems Inc
 *      Author: Sunil V L <sunilvl@ventanamicro.com>
 *
 */

#define pr_fmt(fmt)     "ACPI: RHCT: " fmt

#include <linux/acpi.h>
#include <linux/bits.h>

static struct acpi_table_rhct *acpi_get_rhct(void)
{
        static struct acpi_table_header *rhct;
        acpi_status status;

        /*
         * RHCT will be used at runtime on every CPU, so we
         * don't need to call acpi_put_table() to release the table mapping.
         */
        if (!rhct) {
                status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
                if (ACPI_FAILURE(status)) {
                        pr_warn_once("No RHCT table found\n");
                        return NULL;
                }
        }

        return (struct acpi_table_rhct *)rhct;
}

/*
 * During early boot, the caller should call acpi_get_table() and pass its pointer to
 * these functions(and free up later). At run time, since this table can be used
 * multiple times, NULL may be passed in order to use the cached table.
 */
int acpi_get_riscv_isa(struct acpi_table_header *table, unsigned int cpu, const char **isa)
{
        struct acpi_rhct_node_header *node, *ref_node, *end;
        u32 size_hdr = sizeof(struct acpi_rhct_node_header);
        u32 size_hartinfo = sizeof(struct acpi_rhct_hart_info);
        struct acpi_rhct_hart_info *hart_info;
        struct acpi_rhct_isa_string *isa_node;
        struct acpi_table_rhct *rhct;
        u32 *hart_info_node_offset;
        u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);

        BUG_ON(acpi_disabled);

        if (!table) {
                rhct = acpi_get_rhct();
                if (!rhct)
                        return -ENOENT;
        } else {
                rhct = (struct acpi_table_rhct *)table;
        }

        end = ACPI_ADD_PTR(struct acpi_rhct_node_header, rhct, rhct->header.length);

        for (node = ACPI_ADD_PTR(struct acpi_rhct_node_header, rhct, rhct->node_offset);
             node < end;
             node = ACPI_ADD_PTR(struct acpi_rhct_node_header, node, node->length)) {
                if (node->type == ACPI_RHCT_NODE_TYPE_HART_INFO) {
                        hart_info = ACPI_ADD_PTR(struct acpi_rhct_hart_info, node, size_hdr);
                        hart_info_node_offset = ACPI_ADD_PTR(u32, hart_info, size_hartinfo);
                        if (acpi_cpu_id != hart_info->uid)
                                continue;

                        for (int i = 0; i < hart_info->num_offsets; i++) {
                                ref_node = ACPI_ADD_PTR(struct acpi_rhct_node_header,
                                                        rhct, hart_info_node_offset[i]);
                                if (ref_node->type == ACPI_RHCT_NODE_TYPE_ISA_STRING) {
                                        isa_node = ACPI_ADD_PTR(struct acpi_rhct_isa_string,
                                                                ref_node, size_hdr);
                                        *isa = isa_node->isa;
                                        return 0;
                                }
                        }
                }
        }

        return -1;
}

static void acpi_parse_hart_info_cmo_node(struct acpi_table_rhct *rhct,
                                          struct acpi_rhct_hart_info *hart_info,
                                          u32 *cbom_size, u32 *cboz_size, u32 *cbop_size)
{
        u32 size_hartinfo = sizeof(struct acpi_rhct_hart_info);
        u32 size_hdr = sizeof(struct acpi_rhct_node_header);
        struct acpi_rhct_node_header *ref_node;
        struct acpi_rhct_cmo_node *cmo_node;
        u32 *hart_info_node_offset;

        hart_info_node_offset = ACPI_ADD_PTR(u32, hart_info, size_hartinfo);
        for (int i = 0; i < hart_info->num_offsets; i++) {
                ref_node = ACPI_ADD_PTR(struct acpi_rhct_node_header,
                                        rhct, hart_info_node_offset[i]);
                if (ref_node->type == ACPI_RHCT_NODE_TYPE_CMO) {
                        cmo_node = ACPI_ADD_PTR(struct acpi_rhct_cmo_node,
                                                ref_node, size_hdr);
                        if (cbom_size && cmo_node->cbom_size <= 30) {
                                if (!*cbom_size)
                                        *cbom_size = BIT(cmo_node->cbom_size);
                                else if (*cbom_size != BIT(cmo_node->cbom_size))
                                        pr_warn("CBOM size is not the same across harts\n");
                        }

                        if (cboz_size && cmo_node->cboz_size <= 30) {
                                if (!*cboz_size)
                                        *cboz_size = BIT(cmo_node->cboz_size);
                                else if (*cboz_size != BIT(cmo_node->cboz_size))
                                        pr_warn("CBOZ size is not the same across harts\n");
                        }

                        if (cbop_size && cmo_node->cbop_size <= 30) {
                                if (!*cbop_size)
                                        *cbop_size = BIT(cmo_node->cbop_size);
                                else if (*cbop_size != BIT(cmo_node->cbop_size))
                                        pr_warn("CBOP size is not the same across harts\n");
                        }
                }
        }
}

/*
 * During early boot, the caller should call acpi_get_table() and pass its pointer to
 * these functions (and free up later). At run time, since this table can be used
 * multiple times, pass NULL so that the table remains in memory.
 */
void acpi_get_cbo_block_size(struct acpi_table_header *table, u32 *cbom_size,
                             u32 *cboz_size, u32 *cbop_size)
{
        u32 size_hdr = sizeof(struct acpi_rhct_node_header);
        struct acpi_rhct_node_header *node, *end;
        struct acpi_rhct_hart_info *hart_info;
        struct acpi_table_rhct *rhct;

        if (acpi_disabled)
                return;

        if (table) {
                rhct = (struct acpi_table_rhct *)table;
        } else {
                rhct = acpi_get_rhct();
                if (!rhct)
                        return;
        }

        if (cbom_size)
                *cbom_size = 0;

        if (cboz_size)
                *cboz_size = 0;

        if (cbop_size)
                *cbop_size = 0;

        end = ACPI_ADD_PTR(struct acpi_rhct_node_header, rhct, rhct->header.length);
        for (node = ACPI_ADD_PTR(struct acpi_rhct_node_header, rhct, rhct->node_offset);
             node < end;
             node = ACPI_ADD_PTR(struct acpi_rhct_node_header, node, node->length)) {
                if (node->type == ACPI_RHCT_NODE_TYPE_HART_INFO) {
                        hart_info = ACPI_ADD_PTR(struct acpi_rhct_hart_info, node, size_hdr);
                        acpi_parse_hart_info_cmo_node(rhct, hart_info, cbom_size,
                                                      cboz_size, cbop_size);
                }
        }
}