/*
 * Copyright (C) 2016, Semihalf
 *      Author: Tomasz Nowicki <tn@semihalf.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * This file implements early detection/parsing of I/O mapping
 * reported to OS through firmware via I/O Remapping Table (IORT)
 * IORT document number: ARM DEN 0049A
 */

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

#include <linux/acpi_iort.h>
#include <linux/kernel.h>
#include <linux/pci.h>

struct iort_its_msi_chip {
        struct list_head        list;
        struct fwnode_handle    *fw_node;
        u32                     translation_id;
};

typedef acpi_status (*iort_find_node_callback)
        (struct acpi_iort_node *node, void *context);

/* Root pointer to the mapped IORT table */
static struct acpi_table_header *iort_table;

static LIST_HEAD(iort_msi_chip_list);
static DEFINE_SPINLOCK(iort_msi_chip_lock);

/**
 * iort_register_domain_token() - register domain token and related ITS ID
 * to the list from where we can get it back later on.
 * @trans_id: ITS ID.
 * @fw_node: Domain token.
 *
 * Returns: 0 on success, -ENOMEM if no memory when allocating list element
 */
int iort_register_domain_token(int trans_id, struct fwnode_handle *fw_node)
{
        struct iort_its_msi_chip *its_msi_chip;

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

        its_msi_chip->fw_node = fw_node;
        its_msi_chip->translation_id = trans_id;

        spin_lock(&iort_msi_chip_lock);
        list_add(&its_msi_chip->list, &iort_msi_chip_list);
        spin_unlock(&iort_msi_chip_lock);

        return 0;
}

/**
 * iort_deregister_domain_token() - Deregister domain token based on ITS ID
 * @trans_id: ITS ID.
 *
 * Returns: none.
 */
void iort_deregister_domain_token(int trans_id)
{
        struct iort_its_msi_chip *its_msi_chip, *t;

        spin_lock(&iort_msi_chip_lock);
        list_for_each_entry_safe(its_msi_chip, t, &iort_msi_chip_list, list) {
                if (its_msi_chip->translation_id == trans_id) {
                        list_del(&its_msi_chip->list);
                        kfree(its_msi_chip);
                        break;
                }
        }
        spin_unlock(&iort_msi_chip_lock);
}

/**
 * iort_find_domain_token() - Find domain token based on given ITS ID
 * @trans_id: ITS ID.
 *
 * Returns: domain token when find on the list, NULL otherwise
 */
struct fwnode_handle *iort_find_domain_token(int trans_id)
{
        struct fwnode_handle *fw_node = NULL;
        struct iort_its_msi_chip *its_msi_chip;

        spin_lock(&iort_msi_chip_lock);
        list_for_each_entry(its_msi_chip, &iort_msi_chip_list, list) {
                if (its_msi_chip->translation_id == trans_id) {
                        fw_node = its_msi_chip->fw_node;
                        break;
                }
        }
        spin_unlock(&iort_msi_chip_lock);

        return fw_node;
}

static struct acpi_iort_node *iort_scan_node(enum acpi_iort_node_type type,
                                             iort_find_node_callback callback,
                                             void *context)
{
        struct acpi_iort_node *iort_node, *iort_end;
        struct acpi_table_iort *iort;
        int i;

        if (!iort_table)
                return NULL;

        /* Get the first IORT node */
        iort = (struct acpi_table_iort *)iort_table;
        iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort,
                                 iort->node_offset);
        iort_end = ACPI_ADD_PTR(struct acpi_iort_node, iort_table,
                                iort_table->length);

        for (i = 0; i < iort->node_count; i++) {
                if (WARN_TAINT(iort_node >= iort_end, TAINT_FIRMWARE_WORKAROUND,
                               "IORT node pointer overflows, bad table!\n"))
                        return NULL;

                if (iort_node->type == type &&
                    ACPI_SUCCESS(callback(iort_node, context)))
                                return iort_node;

                iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort_node,
                                         iort_node->length);
        }

        return NULL;
}

static acpi_status iort_match_node_callback(struct acpi_iort_node *node,
                                            void *context)
{
        struct device *dev = context;
        acpi_status status;

        if (node->type == ACPI_IORT_NODE_NAMED_COMPONENT) {
                struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
                struct acpi_device *adev = to_acpi_device_node(dev->fwnode);
                struct acpi_iort_named_component *ncomp;

                if (!adev) {
                        status = AE_NOT_FOUND;
                        goto out;
                }

                status = acpi_get_name(adev->handle, ACPI_FULL_PATHNAME, &buf);
                if (ACPI_FAILURE(status)) {
                        dev_warn(dev, "Can't get device full path name\n");
                        goto out;
                }

                ncomp = (struct acpi_iort_named_component *)node->node_data;
                status = !strcmp(ncomp->device_name, buf.pointer) ?
                                                        AE_OK : AE_NOT_FOUND;
                acpi_os_free(buf.pointer);
        } else if (node->type == ACPI_IORT_NODE_PCI_ROOT_COMPLEX) {
                struct acpi_iort_root_complex *pci_rc;
                struct pci_bus *bus;

                bus = to_pci_bus(dev);
                pci_rc = (struct acpi_iort_root_complex *)node->node_data;

                /*
                 * It is assumed that PCI segment numbers maps one-to-one
                 * with root complexes. Each segment number can represent only
                 * one root complex.
                 */
                status = pci_rc->pci_segment_number == pci_domain_nr(bus) ?
                                                        AE_OK : AE_NOT_FOUND;
        } else {
                status = AE_NOT_FOUND;
        }
out:
        return status;
}

static int iort_id_map(struct acpi_iort_id_mapping *map, u8 type, u32 rid_in,
                       u32 *rid_out)
{
        /* Single mapping does not care for input id */
        if (map->flags & ACPI_IORT_ID_SINGLE_MAPPING) {
                if (type == ACPI_IORT_NODE_NAMED_COMPONENT ||
                    type == ACPI_IORT_NODE_PCI_ROOT_COMPLEX) {
                        *rid_out = map->output_base;
                        return 0;
                }

                pr_warn(FW_BUG "[map %p] SINGLE MAPPING flag not allowed for node type %d, skipping ID map\n",
                        map, type);
                return -ENXIO;
        }

        if (rid_in < map->input_base ||
            (rid_in >= map->input_base + map->id_count))
                return -ENXIO;

        *rid_out = map->output_base + (rid_in - map->input_base);
        return 0;
}

static struct acpi_iort_node *iort_node_map_rid(struct acpi_iort_node *node,
                                                u32 rid_in, u32 *rid_out,
                                                u8 type)
{
        u32 rid = rid_in;

        /* Parse the ID mapping tree to find specified node type */
        while (node) {
                struct acpi_iort_id_mapping *map;
                int i;

                if (node->type == type) {
                        if (rid_out)
                                *rid_out = rid;
                        return node;
                }

                if (!node->mapping_offset || !node->mapping_count)
                        goto fail_map;

                map = ACPI_ADD_PTR(struct acpi_iort_id_mapping, node,
                                   node->mapping_offset);

                /* Firmware bug! */
                if (!map->output_reference) {
                        pr_err(FW_BUG "[node %p type %d] ID map has NULL parent reference\n",
                               node, node->type);
                        goto fail_map;
                }

                /* Do the RID translation */
                for (i = 0; i < node->mapping_count; i++, map++) {
                        if (!iort_id_map(map, node->type, rid, &rid))
                                break;
                }

                if (i == node->mapping_count)
                        goto fail_map;

                node = ACPI_ADD_PTR(struct acpi_iort_node, iort_table,
                                    map->output_reference);
        }

fail_map:
        /* Map input RID to output RID unchanged on mapping failure*/
        if (rid_out)
                *rid_out = rid_in;

        return NULL;
}

static struct acpi_iort_node *iort_find_dev_node(struct device *dev)
{
        struct pci_bus *pbus;

        if (!dev_is_pci(dev))
                return iort_scan_node(ACPI_IORT_NODE_NAMED_COMPONENT,
                                      iort_match_node_callback, dev);

        /* Find a PCI root bus */
        pbus = to_pci_dev(dev)->bus;
        while (!pci_is_root_bus(pbus))
                pbus = pbus->parent;

        return iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
                              iort_match_node_callback, &pbus->dev);
}

/**
 * iort_msi_map_rid() - Map a MSI requester ID for a device
 * @dev: The device for which the mapping is to be done.
 * @req_id: The device requester ID.
 *
 * Returns: mapped MSI RID on success, input requester ID otherwise
 */
u32 iort_msi_map_rid(struct device *dev, u32 req_id)
{
        struct acpi_iort_node *node;
        u32 dev_id;

        node = iort_find_dev_node(dev);
        if (!node)
                return req_id;

        iort_node_map_rid(node, req_id, &dev_id, ACPI_IORT_NODE_ITS_GROUP);
        return dev_id;
}

/**
 * iort_dev_find_its_id() - Find the ITS identifier for a device
 * @dev: The device.
 * @idx: Index of the ITS identifier list.
 * @its_id: ITS identifier.
 *
 * Returns: 0 on success, appropriate error value otherwise
 */
static int iort_dev_find_its_id(struct device *dev, u32 req_id,
                                unsigned int idx, int *its_id)
{
        struct acpi_iort_its_group *its;
        struct acpi_iort_node *node;

        node = iort_find_dev_node(dev);
        if (!node)
                return -ENXIO;

        node = iort_node_map_rid(node, req_id, NULL, ACPI_IORT_NODE_ITS_GROUP);
        if (!node)
                return -ENXIO;

        /* Move to ITS specific data */
        its = (struct acpi_iort_its_group *)node->node_data;
        if (idx > its->its_count) {
                dev_err(dev, "requested ITS ID index [%d] is greater than available [%d]\n",
                        idx, its->its_count);
                return -ENXIO;
        }

        *its_id = its->identifiers[idx];
        return 0;
}

/**
 * iort_get_device_domain() - Find MSI domain related to a device
 * @dev: The device.
 * @req_id: Requester ID for the device.
 *
 * Returns: the MSI domain for this device, NULL otherwise
 */
struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id)
{
        struct fwnode_handle *handle;
        int its_id;

        if (iort_dev_find_its_id(dev, req_id, 0, &its_id))
                return NULL;

        handle = iort_find_domain_token(its_id);
        if (!handle)
                return NULL;

        return irq_find_matching_fwnode(handle, DOMAIN_BUS_PCI_MSI);
}

void __init acpi_iort_init(void)
{
        acpi_status status;

        status = acpi_get_table(ACPI_SIG_IORT, 0, &iort_table);
        if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
                const char *msg = acpi_format_exception(status);
                pr_err("Failed to get table, %s\n", msg);
        }
}