path: root/drivers/acpi/mipi-disco-img.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * MIPI DisCo for Imaging support.
 *
 * Copyright (C) 2023 Intel Corporation
 *
 * Support MIPI DisCo for Imaging by parsing ACPI _CRS CSI-2 records defined in
 * Section 6.4.3.8.2.4 "Camera Serial Interface (CSI-2) Connection Resource
 * Descriptor" of ACPI 6.5.
 *
 * The implementation looks for the information in the ACPI namespace (CSI-2
 * resource descriptors in _CRS) and constructs software nodes compatible with
 * Documentation/firmware-guide/acpi/dsd/graph.rst to represent the CSI-2
 * connection graph.
 */

#include <linux/acpi.h>
#include <linux/limits.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/overflow.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/string.h>

#include "internal.h"

static LIST_HEAD(acpi_mipi_crs_csi2_list);

static void acpi_mipi_data_tag(acpi_handle handle, void *context)
{
}

/* Connection data extracted from one _CRS CSI-2 resource descriptor. */
struct crs_csi2_connection {
	struct list_head entry;
	struct acpi_resource_csi2_serialbus csi2_data;
	acpi_handle remote_handle;
	char remote_name[];
};

/* Data extracted from _CRS CSI-2 resource descriptors for one device. */
struct crs_csi2 {
	struct list_head entry;
	acpi_handle handle;
	struct acpi_device_software_nodes *swnodes;
	struct list_head connections;
	u32 port_count;
};

struct csi2_resources_walk_data {
	acpi_handle handle;
	struct list_head connections;
};

static acpi_status parse_csi2_resource(struct acpi_resource *res, void *context)
{
	struct csi2_resources_walk_data *crwd = context;
	struct acpi_resource_csi2_serialbus *csi2_res;
	struct acpi_resource_source *csi2_res_src;
	u16 csi2_res_src_length;
	struct crs_csi2_connection *conn;
	acpi_handle remote_handle;

	if (res->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
		return AE_OK;

	csi2_res = &res->data.csi2_serial_bus;

	if (csi2_res->type != ACPI_RESOURCE_SERIAL_TYPE_CSI2)
		return AE_OK;

	csi2_res_src = &csi2_res->resource_source;
	if (ACPI_FAILURE(acpi_get_handle(NULL, csi2_res_src->string_ptr,
					 &remote_handle))) {
		acpi_handle_debug(crwd->handle,
				  "unable to find resource source\n");
		return AE_OK;
	}
	csi2_res_src_length = csi2_res_src->string_length;
	if (!csi2_res_src_length) {
		acpi_handle_debug(crwd->handle,
				  "invalid resource source string length\n");
		return AE_OK;
	}

	conn = kmalloc(struct_size(conn, remote_name, csi2_res_src_length + 1),
		       GFP_KERNEL);
	if (!conn)
		return AE_OK;

	conn->csi2_data = *csi2_res;
	strscpy(conn->remote_name, csi2_res_src->string_ptr, csi2_res_src_length);
	conn->csi2_data.resource_source.string_ptr = conn->remote_name;
	conn->remote_handle = remote_handle;

	list_add(&conn->entry, &crwd->connections);

	return AE_OK;
}

static struct crs_csi2 *acpi_mipi_add_crs_csi2(acpi_handle handle,
					       struct list_head *list)
{
	struct crs_csi2 *csi2;

	csi2 = kzalloc(sizeof(*csi2), GFP_KERNEL);
	if (!csi2)
		return NULL;

	csi2->handle = handle;
	INIT_LIST_HEAD(&csi2->connections);
	csi2->port_count = 1;

	if (ACPI_FAILURE(acpi_attach_data(handle, acpi_mipi_data_tag, csi2))) {
		kfree(csi2);
		return NULL;
	}

	list_add(&csi2->entry, list);

	return csi2;
}

static struct crs_csi2 *acpi_mipi_get_crs_csi2(acpi_handle handle)
{
	struct crs_csi2 *csi2;

	if (ACPI_FAILURE(acpi_get_data_full(handle, acpi_mipi_data_tag,
					    (void **)&csi2, NULL)))
		return NULL;

	return csi2;
}

static void csi_csr2_release_connections(struct list_head *list)
{
	struct crs_csi2_connection *conn, *conn_tmp;

	list_for_each_entry_safe(conn, conn_tmp, list, entry) {
		list_del(&conn->entry);
		kfree(conn);
	}
}

static void acpi_mipi_del_crs_csi2(struct crs_csi2 *csi2)
{
	list_del(&csi2->entry);
	acpi_detach_data(csi2->handle, acpi_mipi_data_tag);
	kfree(csi2->swnodes);
	csi_csr2_release_connections(&csi2->connections);
	kfree(csi2);
}

/**
 * acpi_mipi_check_crs_csi2 - Look for CSI-2 resources in _CRS
 * @handle: Device object handle to evaluate _CRS for.
 *
 * Find all CSI-2 resource descriptors in the given device's _CRS
 * and collect them into a list.
 */
void acpi_mipi_check_crs_csi2(acpi_handle handle)
{
	struct csi2_resources_walk_data crwd = {
		.handle = handle,
		.connections = LIST_HEAD_INIT(crwd.connections),
	};
	struct crs_csi2 *csi2;

	/*
	 * Avoid allocating _CRS CSI-2 objects for devices without any CSI-2
	 * resource descriptions in _CRS to reduce overhead.
	 */
	acpi_walk_resources(handle, METHOD_NAME__CRS, parse_csi2_resource, &crwd);
	if (list_empty(&crwd.connections))
		return;

	/*
	 * Create a _CRS CSI-2 entry to store the extracted connection
	 * information and add it to the global list.
	 */
	csi2 = acpi_mipi_add_crs_csi2(handle, &acpi_mipi_crs_csi2_list);
	if (!csi2) {
		csi_csr2_release_connections(&crwd.connections);
		return; /* Nothing really can be done about this. */
	}

	list_replace(&crwd.connections, &csi2->connections);
}

#define NO_CSI2_PORT (UINT_MAX - 1)

static void alloc_crs_csi2_swnodes(struct crs_csi2 *csi2)
{
	size_t port_count = csi2->port_count;
	struct acpi_device_software_nodes *swnodes;
	size_t alloc_size;
	unsigned int i;

	/*
	 * Allocate memory for ports, node pointers (number of nodes +
	 * 1 (guardian), nodes (root + number of ports * 2 (because for
	 * every port there is an endpoint)).
	 */
	if (check_mul_overflow(sizeof(*swnodes->ports) +
			       sizeof(*swnodes->nodes) * 2 +
			       sizeof(*swnodes->nodeptrs) * 2,
			       port_count, &alloc_size) ||
	    check_add_overflow(sizeof(*swnodes) +
			       sizeof(*swnodes->nodes) +
			       sizeof(*swnodes->nodeptrs) * 2,
			       alloc_size, &alloc_size)) {
		acpi_handle_info(csi2->handle,
				 "too many _CRS CSI-2 resource handles (%zu)",
				 port_count);
		return;
	}

	swnodes = kmalloc(alloc_size, GFP_KERNEL);
	if (!swnodes)
		return;

	swnodes->ports = (struct acpi_device_software_node_port *)(swnodes + 1);
	swnodes->nodes = (struct software_node *)(swnodes->ports + port_count);
	swnodes->nodeptrs = (const struct software_node **)(swnodes->nodes + 1 +
				2 * port_count);
	swnodes->num_ports = port_count;

	for (i = 0; i < 2 * port_count + 1; i++)
		swnodes->nodeptrs[i] = &swnodes->nodes[i];

	swnodes->nodeptrs[i] = NULL;

	for (i = 0; i < port_count; i++)
		swnodes->ports[i].port_nr = NO_CSI2_PORT;

	csi2->swnodes = swnodes;
}

/**
 * acpi_mipi_scan_crs_csi2 - Create ACPI _CRS CSI-2 software nodes
 *
 * Note that this function must be called before any struct acpi_device objects
 * are bound to any ACPI drivers or scan handlers, so it cannot assume the
 * existence of struct acpi_device objects for every device present in the ACPI
 * namespace.
 *
 * acpi_scan_lock in scan.c must be held when calling this function.
 */
void acpi_mipi_scan_crs_csi2(void)
{
	struct crs_csi2 *csi2;
	LIST_HEAD(aux_list);

	/* Count references to each ACPI handle in the CSI-2 connection graph. */
	list_for_each_entry(csi2, &acpi_mipi_crs_csi2_list, entry) {
		struct crs_csi2_connection *conn;

		list_for_each_entry(conn, &csi2->connections, entry) {
			struct crs_csi2 *remote_csi2;

			csi2->port_count++;

			remote_csi2 = acpi_mipi_get_crs_csi2(conn->remote_handle);
			if (remote_csi2) {
				remote_csi2->port_count++;
				continue;
			}
			/*
			 * The remote endpoint has no _CRS CSI-2 list entry yet,
			 * so create one for it and add it to the list.
			 */
			acpi_mipi_add_crs_csi2(conn->remote_handle, &aux_list);
		}
	}
	list_splice(&aux_list, &acpi_mipi_crs_csi2_list);

	/* Allocate software nodes for representing the CSI-2 information. */
	list_for_each_entry(csi2, &acpi_mipi_crs_csi2_list, entry)
		alloc_crs_csi2_swnodes(csi2);
}

/**
 * acpi_mipi_crs_csi2_cleanup - Free _CRS CSI-2 temporary data
 */
void acpi_mipi_crs_csi2_cleanup(void)
{
	struct crs_csi2 *csi2, *csi2_tmp;

	list_for_each_entry_safe(csi2, csi2_tmp, &acpi_mipi_crs_csi2_list, entry)
		acpi_mipi_del_crs_csi2(csi2);
}