/*
 * 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>

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);

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);
}

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);
	}
}