media: ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver

Currently on platforms designed for Windows, connections between CIO2 and
sensors are not properly defined in DSDT. This patch extends the ipu3-cio2
driver to compensate by building software_node connections, parsing the
connection properties from the sensor's SSDB buffer.

[Sakari Ailus: Make cio2_bridge_init static inline to a fix compiler
	       warning, wrapped a bunch of long lines.]

Suggested-by: Jordan Hand <jorhand@linux.microsoft.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Daniel Scally <djrscally@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

MAINTAINERS

@@ -9014,6 +9014,7 @@ INTEL IPU3 CSI-2 CIO2 DRIVER
 M:	Yong Zhi <yong.zhi@intel.com>
 M:	Sakari Ailus <sakari.ailus@linux.intel.com>
 M:	Bingbu Cao <bingbu.cao@intel.com>
+M:	Dan Scally <djrscally@gmail.com>
 R:	Tianshu Qiu <tian.shu.qiu@intel.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained

drivers/media/pci/intel/ipu3/Kconfig

@@ -17,3 +17,21 @@ config VIDEO_IPU3_CIO2
 	  Say Y or M here if you have a Skylake/Kaby Lake SoC with MIPI CSI-2
 	  connected camera.
 	  The module will be called ipu3-cio2.
+
+config CIO2_BRIDGE
+	bool "IPU3 CIO2 Sensors Bridge"
+	depends on VIDEO_IPU3_CIO2
+	help
+	  This extension provides an API for the ipu3-cio2 driver to create
+	  connections to cameras that are hidden in the SSDB buffer in ACPI.
+	  It can be used to enable support for cameras in detachable / hybrid
+	  devices that ship with Windows.
+
+	  Say Y here if your device is a detachable / hybrid laptop that comes
+	  with Windows installed by the OEM, for example:
+
+		- Microsoft Surface models (except Surface Pro 3)
+		- The Lenovo Miix line (for example the 510, 520, 710 and 720)
+		- Dell 7285
+
+	  If in doubt, say N here.

drivers/media/pci/intel/ipu3/Makefile

@@ -2,3 +2,4 @@
 obj-$(CONFIG_VIDEO_IPU3_CIO2) += ipu3-cio2.o
 
 ipu3-cio2-y += ipu3-cio2-main.o
+ipu3-cio2-$(CONFIG_CIO2_BRIDGE) += cio2-bridge.o

drivers/media/pci/intel/ipu3/cio2-bridge.c

@@ -0,0 +1,314 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Author: Dan Scally <djrscally@gmail.com> */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/pci.h>
+#include <linux/property.h>
+#include <media/v4l2-fwnode.h>
+
+#include "cio2-bridge.h"
+
+/*
+ * Extend this array with ACPI Hardware IDs of devices known to be working
+ * plus the number of link-frequencies expected by their drivers, along with
+ * the frequency values in hertz. This is somewhat opportunistic way of adding
+ * support for this for now in the hopes of a better source for the information
+ * (possibly some encoded value in the SSDB buffer that we're unaware of)
+ * becoming apparent in the future.
+ *
+ * Do not add an entry for a sensor that is not actually supported.
+ */
+static const struct cio2_sensor_config cio2_supported_sensors[] = {
+	/* Omnivision OV5693 */
+	CIO2_SENSOR_CONFIG("INT33BE", 0),
+	/* Omnivision OV2680 */
+	CIO2_SENSOR_CONFIG("OVTI2680", 0),
+};
+
+static const struct cio2_property_names prop_names = {
+	.clock_frequency = "clock-frequency",
+	.rotation = "rotation",
+	.bus_type = "bus-type",
+	.data_lanes = "data-lanes",
+	.remote_endpoint = "remote-endpoint",
+	.link_frequencies = "link-frequencies",
+};
+
+static int cio2_bridge_read_acpi_buffer(struct acpi_device *adev, char *id,
+					void *data, u32 size)
+{
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	acpi_status status;
+	int ret = 0;
+
+	status = acpi_evaluate_object(adev->handle, id, NULL, &buffer);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	obj = buffer.pointer;
+	if (!obj) {
+		dev_err(&adev->dev, "Couldn't locate ACPI buffer\n");
+		return -ENODEV;
+	}
+
+	if (obj->type != ACPI_TYPE_BUFFER) {
+		dev_err(&adev->dev, "Not an ACPI buffer\n");
+		ret = -ENODEV;
+		goto out_free_buff;
+	}
+
+	if (obj->buffer.length > size) {
+		dev_err(&adev->dev, "Given buffer is too small\n");
+		ret = -EINVAL;
+		goto out_free_buff;
+	}
+
+	memcpy(data, obj->buffer.pointer, obj->buffer.length);
+
+out_free_buff:
+	kfree(buffer.pointer);
+	return ret;
+}
+
+static void cio2_bridge_create_fwnode_properties(
+	struct cio2_sensor *sensor,
+	struct cio2_bridge *bridge,
+	const struct cio2_sensor_config *cfg)
+{
+	sensor->prop_names = prop_names;
+
+	sensor->local_ref[0].node = &sensor->swnodes[SWNODE_CIO2_ENDPOINT];
+	sensor->remote_ref[0].node = &sensor->swnodes[SWNODE_SENSOR_ENDPOINT];
+
+	sensor->dev_properties[0] = PROPERTY_ENTRY_U32(
+					sensor->prop_names.clock_frequency,
+					sensor->ssdb.mclkspeed);
+	sensor->dev_properties[1] = PROPERTY_ENTRY_U8(
+					sensor->prop_names.rotation,
+					sensor->ssdb.degree);
+
+	sensor->ep_properties[0] = PROPERTY_ENTRY_U32(
+					sensor->prop_names.bus_type,
+					V4L2_FWNODE_BUS_TYPE_CSI2_DPHY);
+	sensor->ep_properties[1] = PROPERTY_ENTRY_U32_ARRAY_LEN(
+					sensor->prop_names.data_lanes,
+					bridge->data_lanes,
+					sensor->ssdb.lanes);
+	sensor->ep_properties[2] = PROPERTY_ENTRY_REF_ARRAY(
+					sensor->prop_names.remote_endpoint,
+					sensor->local_ref);
+
+	if (cfg->nr_link_freqs > 0)
+		sensor->ep_properties[3] = PROPERTY_ENTRY_U64_ARRAY_LEN(
+			sensor->prop_names.link_frequencies,
+			cfg->link_freqs,
+			cfg->nr_link_freqs);
+
+	sensor->cio2_properties[0] = PROPERTY_ENTRY_U32_ARRAY_LEN(
+					sensor->prop_names.data_lanes,
+					bridge->data_lanes,
+					sensor->ssdb.lanes);
+	sensor->cio2_properties[1] = PROPERTY_ENTRY_REF_ARRAY(
+					sensor->prop_names.remote_endpoint,
+					sensor->remote_ref);
+}
+
+static void cio2_bridge_init_swnode_names(struct cio2_sensor *sensor)
+{
+	snprintf(sensor->node_names.remote_port,
+		 sizeof(sensor->node_names.remote_port),
+		 SWNODE_GRAPH_PORT_NAME_FMT, sensor->ssdb.link);
+	snprintf(sensor->node_names.port,
+		 sizeof(sensor->node_names.port),
+		 SWNODE_GRAPH_PORT_NAME_FMT, 0); /* Always port 0 */
+	snprintf(sensor->node_names.endpoint,
+		 sizeof(sensor->node_names.endpoint),
+		 SWNODE_GRAPH_ENDPOINT_NAME_FMT, 0); /* And endpoint 0 */
+}
+
+static void cio2_bridge_create_connection_swnodes(struct cio2_bridge *bridge,
+						  struct cio2_sensor *sensor)
+{
+	struct software_node *nodes = sensor->swnodes;
+
+	cio2_bridge_init_swnode_names(sensor);
+
+	nodes[SWNODE_SENSOR_HID] = NODE_SENSOR(sensor->name,
+					       sensor->dev_properties);
+	nodes[SWNODE_SENSOR_PORT] = NODE_PORT(sensor->node_names.port,
+					      &nodes[SWNODE_SENSOR_HID]);
+	nodes[SWNODE_SENSOR_ENDPOINT] = NODE_ENDPOINT(
+						sensor->node_names.endpoint,
+						&nodes[SWNODE_SENSOR_PORT],
+						sensor->ep_properties);
+	nodes[SWNODE_CIO2_PORT] = NODE_PORT(sensor->node_names.remote_port,
+					    &bridge->cio2_hid_node);
+	nodes[SWNODE_CIO2_ENDPOINT] = NODE_ENDPOINT(
+						sensor->node_names.endpoint,
+						&nodes[SWNODE_CIO2_PORT],
+						sensor->cio2_properties);
+}
+
+static void cio2_bridge_unregister_sensors(struct cio2_bridge *bridge)
+{
+	struct cio2_sensor *sensor;
+	unsigned int i;
+
+	for (i = 0; i < bridge->n_sensors; i++) {
+		sensor = &bridge->sensors[i];
+		software_node_unregister_nodes(sensor->swnodes);
+		acpi_dev_put(sensor->adev);
+	}
+}
+
+static int cio2_bridge_connect_sensor(const struct cio2_sensor_config *cfg,
+				      struct cio2_bridge *bridge,
+				      struct pci_dev *cio2)
+{
+	struct fwnode_handle *fwnode;
+	struct cio2_sensor *sensor;
+	struct acpi_device *adev;
+	int ret;
+
+	for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {
+		if (!adev->status.enabled)
+			continue;
+
+		if (bridge->n_sensors >= CIO2_NUM_PORTS) {
+			dev_err(&cio2->dev, "Exceeded available CIO2 ports\n");
+			cio2_bridge_unregister_sensors(bridge);
+			ret = -EINVAL;
+			goto err_out;
+		}
+
+		sensor = &bridge->sensors[bridge->n_sensors];
+		sensor->adev = adev;
+		strscpy(sensor->name, cfg->hid, sizeof(sensor->name));
+
+		ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
+						   &sensor->ssdb,
+						   sizeof(sensor->ssdb));
+		if (ret)
+			goto err_put_adev;
+
+		if (sensor->ssdb.lanes > CIO2_MAX_LANES) {
+			dev_err(&adev->dev,
+				"Number of lanes in SSDB is invalid\n");
+			ret = -EINVAL;
+			goto err_put_adev;
+		}
+
+		cio2_bridge_create_fwnode_properties(sensor, bridge, cfg);
+		cio2_bridge_create_connection_swnodes(bridge, sensor);
+
+		ret = software_node_register_nodes(sensor->swnodes);
+		if (ret)
+			goto err_put_adev;
+
+		fwnode = software_node_fwnode(&sensor->swnodes[
+						      SWNODE_SENSOR_HID]);
+		if (!fwnode) {
+			ret = -ENODEV;
+			goto err_free_swnodes;
+		}
+
+		adev->fwnode.secondary = fwnode;
+
+		dev_info(&cio2->dev, "Found supported sensor %s\n",
+			 acpi_dev_name(adev));
+
+		bridge->n_sensors++;
+	}
+
+	return 0;
+
+err_free_swnodes:
+	software_node_unregister_nodes(sensor->swnodes);
+err_put_adev:
+	acpi_dev_put(sensor->adev);
+err_out:
+	return ret;
+}
+
+static int cio2_bridge_connect_sensors(struct cio2_bridge *bridge,
+				       struct pci_dev *cio2)
+{
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(cio2_supported_sensors); i++) {
+		const struct cio2_sensor_config *cfg =
+			&cio2_supported_sensors[i];
+
+		ret = cio2_bridge_connect_sensor(cfg, bridge, cio2);
+		if (ret)
+			goto err_unregister_sensors;
+	}
+
+	return 0;
+
+err_unregister_sensors:
+	cio2_bridge_unregister_sensors(bridge);
+	return ret;
+}
+
+int cio2_bridge_init(struct pci_dev *cio2)
+{
+	struct device *dev = &cio2->dev;
+	struct fwnode_handle *fwnode;
+	struct cio2_bridge *bridge;
+	unsigned int i;
+	int ret;
+
+	bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
+	if (!bridge)
+		return -ENOMEM;
+
+	strscpy(bridge->cio2_node_name, CIO2_HID,
+		sizeof(bridge->cio2_node_name));
+	bridge->cio2_hid_node.name = bridge->cio2_node_name;
+
+	ret = software_node_register(&bridge->cio2_hid_node);
+	if (ret < 0) {
+		dev_err(dev, "Failed to register the CIO2 HID node\n");
+		goto err_free_bridge;
+	}
+
+	/*
+	 * Map the lane arrangement, which is fixed for the IPU3 (meaning we
+	 * only need one, rather than one per sensor). We include it as a
+	 * member of the struct cio2_bridge rather than a global variable so
+	 * that it survives if the module is unloaded along with the rest of
+	 * the struct.
+	 */
+	for (i = 0; i < CIO2_MAX_LANES; i++)
+		bridge->data_lanes[i] = i + 1;
+
+	ret = cio2_bridge_connect_sensors(bridge, cio2);
+	if (ret || bridge->n_sensors == 0)
+		goto err_unregister_cio2;
+
+	dev_info(dev, "Connected %d cameras\n", bridge->n_sensors);
+
+	fwnode = software_node_fwnode(&bridge->cio2_hid_node);
+	if (!fwnode) {
+		dev_err(dev, "Error getting fwnode from cio2 software_node\n");
+		ret = -ENODEV;
+		goto err_unregister_sensors;
+	}
+
+	set_secondary_fwnode(dev, fwnode);
+
+	return 0;
+
+err_unregister_sensors:
+	cio2_bridge_unregister_sensors(bridge);
+err_unregister_cio2:
+	software_node_unregister(&bridge->cio2_hid_node);
+err_free_bridge:
+	kfree(bridge);
+
+	return ret;
+}