[v2,2/8] ACPI: property: Parse _CRS CSI-2 descriptor

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index a5b649e71ab1b..a98fa1bc15548 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -37,7 +37,7 @@  acpi-$(CONFIG_ACPI_SLEEP)	+= proc.o
 # ACPI Bus and Device Drivers
 #
 acpi-y				+= bus.o glue.o
-acpi-y				+= scan.o
+acpi-y				+= scan.o mipi.o
 acpi-y				+= resource.o
 acpi-y				+= acpi_processor.o
 acpi-y				+= processor_core.o
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index ec584442fb298..1ec4aa92bf17a 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -282,4 +282,11 @@  void acpi_init_lpit(void);
 static inline void acpi_init_lpit(void) { }
 #endif
 
+/*--------------------------------------------------------------------------
+				ACPI and MIPI DisCo for Imaging conversion
+  -------------------------------------------------------------------------- */
+
+void acpi_crs_csi2_swnodes_del_free(void);
+void acpi_bus_scan_crs_csi2(acpi_handle handle);
+
 #endif /* _ACPI_INTERNAL_H_ */
diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
new file mode 100644
index 0000000000000..2a8cd8ee074e3
--- /dev/null
+++ b/drivers/acpi/mipi.c
@@ -0,0 +1,320 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MIPI DisCo for Imaging support.
+ *
+ * Copyright (C) 2023 Intel Corporation
+ */
+
+#include <linux/acpi.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/sort.h>
+#include <linux/string.h>
+
+#include "internal.h"
+
+struct crs_csi2_swnodes {
+	struct list_head list;
+	acpi_handle handle;
+	struct acpi_device_software_nodes *ads;
+};
+
+static LIST_HEAD(crs_csi2_swnodes);
+
+static void crs_csi2_swnode_del_free(struct crs_csi2_swnodes *swnodes)
+{
+	list_del(&swnodes->list);
+	kfree(swnodes);
+}
+
+void acpi_crs_csi2_swnodes_del_free(void)
+{
+	struct crs_csi2_swnodes *swnodes, *swnodes_tmp;
+
+	list_for_each_entry_safe(swnodes, swnodes_tmp, &crs_csi2_swnodes, list)
+		crs_csi2_swnode_del_free(swnodes);
+}
+
+struct crs_csi2_instance {
+	struct list_head list;
+	struct acpi_resource_csi2_serialbus csi2;
+	acpi_handle remote_handle;
+	char remote_name[];
+};
+
+struct crs_csi2 {
+	struct list_head list;
+	acpi_handle handle;
+	struct list_head buses;
+};
+
+struct scan_check_crs_csi2_context {
+	struct list_head res_list;
+	acpi_handle handle;
+};
+
+static acpi_status scan_check_crs_csi2_instance(struct acpi_resource *res,
+						void *context)
+{
+	struct scan_check_crs_csi2_context *inst_context = context;
+	struct acpi_resource_csi2_serialbus *csi2;
+	struct crs_csi2_instance *inst;
+	acpi_handle remote_handle;
+	acpi_status status;
+
+	if (res->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return AE_OK;
+
+	csi2 = &res->data.csi2_serial_bus;
+
+	if (csi2->type != ACPI_RESOURCE_SERIAL_TYPE_CSI2)
+		return AE_OK;
+
+	if (!csi2->resource_source.string_length) {
+		acpi_handle_debug(inst_context->handle,
+				  "invalid resource source string length\n");
+		return AE_OK;
+	}
+
+	status = acpi_get_handle(NULL, csi2->resource_source.string_ptr,
+				 &remote_handle);
+	if (status != AE_OK) {
+		acpi_handle_warn(inst_context->handle,
+				 "cannot get handle for %s\n",
+				 csi2->resource_source.string_ptr);
+		return AE_OK;
+	}
+
+	inst = kmalloc(struct_size(inst, remote_name,
+				   csi2->resource_source.string_length),
+		       GFP_KERNEL);
+	if (!inst)
+		return AE_OK;
+
+	inst->csi2 = *csi2;
+	memcpy(inst->remote_name, csi2->resource_source.string_ptr,
+	       csi2->resource_source.string_length);
+	inst->csi2.resource_source.string_ptr = inst->remote_name;
+	inst->remote_handle = remote_handle;
+
+	list_add(&inst->list, &inst_context->res_list);
+
+	return AE_OK;
+}
+
+static acpi_status scan_check_crs_csi2(acpi_handle handle, u32 nesting_level,
+				       void *context, void **ret)
+{
+	struct scan_check_crs_csi2_context inst_context = {
+		.handle = handle,
+		.res_list = LIST_HEAD_INIT(inst_context.res_list),
+	};
+	struct list_head *list = context;
+	struct crs_csi2 *csi2;
+
+	INIT_LIST_HEAD(&inst_context.res_list);
+
+	acpi_walk_resources(handle, METHOD_NAME__CRS,
+			    scan_check_crs_csi2_instance, &inst_context);
+
+	if (list_empty(&inst_context.res_list))
+		return AE_OK;
+
+	csi2 = kmalloc(sizeof(*csi2), GFP_KERNEL);
+	if (!csi2)
+		return AE_OK;
+
+	csi2->handle = handle;
+	list_replace(&inst_context.res_list, &csi2->buses);
+	list_add(&csi2->list, list);
+
+	return AE_OK;
+}
+
+struct acpi_handle_ref {
+	acpi_handle handle;
+	unsigned int count;
+};
+
+#define NO_CSI2_PORT (~1U)
+
+static int crs_handle_cmp(const void *__a, const void *__b)
+{
+	const struct acpi_handle_ref *a = __a, *b = __b;
+
+	return a->handle < b->handle ? -1 : a->handle > b->handle;
+}
+
+static void crs_csi2_release(struct list_head *crs_csi2_handles)
+{
+	struct crs_csi2 *csi2, *csi2_tmp;
+
+	list_for_each_entry_safe(csi2, csi2_tmp, crs_csi2_handles, list) {
+		struct crs_csi2_instance *inst, *inst_tmp;
+
+		list_for_each_entry_safe(inst, inst_tmp, &csi2->buses, list) {
+			list_del(&inst->list);
+			kfree(inst);
+		}
+
+		list_del(&csi2->list);
+		kfree(csi2);
+	}
+}
+
+/**
+ * acpi_bus_scan_crs_csi2 - Scan a device and its child devices for _CRS CSI-2
+ *
+ * @handle: ACPI handle to scan
+ *
+ * This function does a number of things:
+ *
+ * 1. Scan an ACPI device and its children for _CRS CSI-2 instances. The
+ *    instances are stored for later use.
+ *
+ * 2. Count how many references to other devices _CRS CSI-2 instances have in
+ *    total.
+ *
+ * 3. Count the number of references to other devices for each _CRS CSI-2
+ *    instance.
+ *
+ * 4. Allocate memory for swnodes each ACPI device requires later on, and
+ *    generate a list of such allocations.
+ *
+ * Note that struct acpi_device isn't available yet at this time.
+ *
+ * acpi_scan_lock in scan.c must be held when calling this function.
+ */
+void acpi_bus_scan_crs_csi2(acpi_handle handle)
+{
+	struct acpi_handle_ref *handle_refs;
+	struct acpi_handle_ref *this = NULL;
+	LIST_HEAD(crs_csi2_handles);
+	unsigned int handle_count = 0, this_count;
+	unsigned int curr = 0;
+	struct crs_csi2 *csi2;
+
+	/* Collect the devices that have a _CRS CSI-2 resource */
+	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, ACPI_UINT32_MAX,
+			    scan_check_crs_csi2, NULL, &crs_csi2_handles, NULL);
+
+	/*
+	 * Figure out how much temporary storage we need for counting
+	 * connections in each device.
+	 */
+	list_for_each_entry(csi2, &crs_csi2_handles, list) {
+		struct crs_csi2_instance *inst;
+
+		handle_count++;
+
+		list_for_each_entry(inst, &csi2->buses, list)
+			handle_count++;
+	}
+
+	/* No handles? Bail out here. */
+	if (!handle_count)
+		return;
+
+	handle_refs = kcalloc(handle_count + 1, sizeof(*handle_refs),
+			      GFP_KERNEL);
+	if (!handle_refs) {
+		acpi_handle_debug(handle, "no memory for %u handle refs\n",
+				  handle_count + 1);
+		return;
+	}
+
+	/* Associate handles to the number of references. */
+	list_for_each_entry(csi2, &crs_csi2_handles, list) {
+		struct crs_csi2_instance *inst;
+		struct acpi_handle_ref *handle_ref;
+
+		handle_ref = &handle_refs[curr++];
+		handle_ref->handle = csi2->handle;
+
+		list_for_each_entry(inst, &csi2->buses, list) {
+			handle_refs[curr].handle = inst->remote_handle;
+			handle_refs[curr].count = 1;
+			handle_ref->count++;
+			curr++;
+		}
+	}
+
+	handle_refs[curr].handle = NULL;
+
+	sort(handle_refs, handle_count, sizeof(*handle_refs), crs_handle_cmp,
+	     NULL);
+
+	/*
+	 * Finally count references in each handle, allocate space for device
+	 * specific ports, properties and fill the _CRS CSI2 descriptor
+	 * originated data.
+	 */
+	this = handle_refs;
+	this_count = this->count;
+	for (curr = 1; curr < handle_count + 1; curr++) {
+		struct acpi_device_software_nodes *ads;
+		struct crs_csi2_swnodes *swnodes;
+		size_t alloc_size;
+		void *end;
+
+		if (this->handle == handle_refs[curr].handle) {
+			this_count += handle_refs[curr].count;
+			continue;
+		}
+
+		/*
+		 * Allocate memory for ports, node pointers (number of nodes +
+		 * 1 (guardian), nodes (root + number of ports * 2 (for for
+		 * every port there is an endpoint)).
+		 */
+		if (check_mul_overflow(sizeof(*ads->ports) +
+				       sizeof(*ads->nodes) * 2 +
+				       sizeof(*ads->nodeptrs) * 2,
+				       (size_t)this_count, &alloc_size) ||
+		    check_add_overflow(sizeof(*ads) + sizeof(*ads->nodes) +
+				       sizeof(*ads->nodeptrs) * 2,
+				       alloc_size, &alloc_size)) {
+			acpi_handle_warn(handle, "too many handles (%u)",
+					 this_count);
+			continue;
+		}
+
+		swnodes = kzalloc(sizeof(*swnodes), GFP_KERNEL);
+		ads = kzalloc(alloc_size, GFP_KERNEL);
+		ads->ports = (void *)(ads + 1);
+		ads->nodes = (void *)(ads->ports + this_count);
+		ads->nodeptrs = (void *)(ads->nodes +
+					 this_count * 2 + 1);
+		end = ads->nodeptrs + this_count * 2 + 2;
+		if (!swnodes || !ads ||
+		    WARN_ON((void *)ads + alloc_size != end)) {
+			kfree(swnodes);
+			kfree(ads);
+			acpi_handle_debug(handle,
+					  "cannot allocate for %u swnodes\n",
+					  this_count);
+		} else {
+			unsigned int i;
+
+			ads->num_ports = this_count;
+			for (i = 0; i < this_count * 2 + 1; i++)
+				ads->nodeptrs[i] = &ads->nodes[i];
+			ads->nodeptrs[i] = NULL;
+			for (i = 0; i < this_count; i++)
+				ads->ports[i].port_nr = NO_CSI2_PORT;
+			swnodes->handle = this->handle;
+			swnodes->ads = ads;
+			list_add(&swnodes->list, &crs_csi2_swnodes);
+		}
+
+		this = &handle_refs[curr];
+		this_count = this->count;
+	}
+
+	kfree(handle_refs);
+
+	crs_csi2_release(&crs_csi2_handles);
+}
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 0c6f06abe3f47..50de874b8f208 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2423,9 +2423,12 @@  EXPORT_SYMBOL_GPL(acpi_dev_get_next_consumer_dev);
 int acpi_bus_scan(acpi_handle handle)
 {
 	struct acpi_device *device = NULL;
+	int ret = 0;
 
 	acpi_bus_scan_second_pass = false;
 
+	acpi_bus_scan_crs_csi2(handle);
+
 	/* Pass 1: Avoid enumerating devices with missing dependencies. */
 
 	if (ACPI_SUCCESS(acpi_bus_check_add(handle, true, &device)))
@@ -2433,13 +2436,15 @@  int acpi_bus_scan(acpi_handle handle)
 				    acpi_bus_check_add_1, NULL, NULL,
 				    (void **)&device);
 
-	if (!device)
-		return -ENODEV;
+	if (!device) {
+		ret = -ENODEV;
+		goto out_release;
+	}
 
 	acpi_bus_attach(device, (void *)true);
 
 	if (!acpi_bus_scan_second_pass)
-		return 0;
+		goto out_release;
 
 	/* Pass 2: Enumerate all of the remaining devices. */
 
@@ -2452,7 +2457,10 @@  int acpi_bus_scan(acpi_handle handle)
 
 	acpi_bus_attach(device, NULL);
 
-	return 0;
+out_release:
+	acpi_crs_csi2_swnodes_del_free();
+
+	return ret;
 }
 EXPORT_SYMBOL(acpi_bus_scan);
 
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index e44be31115a67..a05fe22c1175c 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -360,6 +360,17 @@  struct acpi_device_data {
 
 struct acpi_gpio_mapping;
 
+struct acpi_device_software_node_port {
+	unsigned int port_nr;
+};
+
+struct acpi_device_software_nodes {
+	struct acpi_device_software_node_port *ports;
+	struct software_node *nodes;
+	const struct software_node **nodeptrs;
+	unsigned int num_ports;
+};
+
 /* Device */
 struct acpi_device {
 	u32 pld_crc;