[PATCH 13/18] ipu3-cio2: Add functionality allowing software_node connections to sensors on platforms designed for Windows

[Daniel Scally <djrscally@gmail.com>]

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.

Suggested-by: Jordan Hand <jorhand@linux.microsoft.com>
Signed-off-by: Daniel Scally <djrscally@gmail.com>
---
Changes since RFC v3:

	- Removed almost all global variables, dynamically allocated
	the cio2_bridge structure, plus a bunch of associated changes
	like 
	- Added a new function to ipu3-cio2-main.c to check for an 
	existing fwnode_graph before calling cio2_bridge_init()
	- Prefixed cio2_bridge_ to any variables and functions that
	lacked it
	- Assigned the new fwnode directly to the sensor's ACPI device
	fwnode as secondary. This removes the requirement to delay until
	the I2C devices are instantiated before ipu3-cio2 can probe, but
	it has a side effect, which is that those devices then grab a ref
	to the new software_node. This effectively prevents us from
	unloading the driver, because we can't free the memory that they
	live in whilst the device holds a reference to them. The work
	around at the moment is to _not_ unregister the software_nodes
	when ipu3-cio2 is unloaded; this becomes a one-time 'patch', that
	is simply skipped if the module is reloaded.
	- Moved the sensor's SSDB struct to be a member of cio2_sensor
	- Replaced ints with unsigned ints where appropriate
	- Iterated over all ACPI devices of a matching _HID rather than
	just the first to ensure we handle a device with multiple sensors
	of the same model.

 MAINTAINERS                                   |   1 +
 drivers/media/pci/intel/ipu3/Kconfig          |  18 ++
 drivers/media/pci/intel/ipu3/Makefile         |   1 +
 drivers/media/pci/intel/ipu3/cio2-bridge.c    | 260 ++++++++++++++++++
 drivers/media/pci/intel/ipu3/cio2-bridge.h    | 108 ++++++++
 drivers/media/pci/intel/ipu3/ipu3-cio2-main.c |  27 ++
 drivers/media/pci/intel/ipu3/ipu3-cio2.h      |   6 +
 7 files changed, 421 insertions(+)
 create mode 100644 drivers/media/pci/intel/ipu3/cio2-bridge.c
 create mode 100644 drivers/media/pci/intel/ipu3/cio2-bridge.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 9702b886d6a4..188559a0a610 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8927,6 +8927,7 @@ 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
diff --git a/drivers/media/pci/intel/ipu3/Kconfig b/drivers/media/pci/intel/ipu3/Kconfig
index 82d7f17e6a02..2b3350d042be 100644
--- a/drivers/media/pci/intel/ipu3/Kconfig
+++ b/drivers/media/pci/intel/ipu3/Kconfig
@@ -16,3 +16,21 @@ 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 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.
diff --git a/drivers/media/pci/intel/ipu3/Makefile b/drivers/media/pci/intel/ipu3/Makefile
index 429d516452e4..933777e6ea8a 100644
--- a/drivers/media/pci/intel/ipu3/Makefile
+++ b/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
diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c
new file mode 100644
index 000000000000..fd3f8ba07274
--- /dev/null
+++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Author: Dan Scally <djrscally@gmail.com> */
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/property.h>
+#include <media/v4l2-subdev.h>
+
+#include "cio2-bridge.h"
+
+/*
+ * Extend this array with ACPI Hardware ID's of devices known to be working.
+ * Do not add a HID for a sensor that is not actually supported.
+ */
+static const char * const cio2_supported_devices[] = {
+	"INT33BE",
+	"OVTI2680",
+};
+
+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;
+
+	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);
+	ret = obj->buffer.length;
+
+out_free_buff:
+	kfree(buffer.pointer);
+	return ret;
+}
+
+static void cio2_bridge_init_property_names(struct cio2_sensor *sensor)
+{
+	strcpy(sensor->prop_names.clock_frequency, "clock-frequency");
+	strcpy(sensor->prop_names.rotation, "rotation");
+	strcpy(sensor->prop_names.bus_type, "bus-type");
+	strcpy(sensor->prop_names.data_lanes, "data-lanes");
+	strcpy(sensor->prop_names.remote_endpoint, "remote-endpoint");
+}
+
+static void cio2_bridge_create_fwnode_properties(struct cio2_sensor *sensor)
+{
+	unsigned int i;
+
+	cio2_bridge_init_property_names(sensor);
+
+	for (i = 0; i < 4; i++)
+		sensor->data_lanes[i] = i + 1;
+
+	/*
+	 * Can't use PROPERTY_ENTRY_REF because it creates a new variable to
+	 * point to, which doesn't survive the function.
+	 */
+	sensor->local_ref[0] = (struct software_node_ref_args){
+		.node = &sensor->swnodes[SWNODE_CIO2_ENDPOINT]
+		};
+	sensor->remote_ref[0] = (struct software_node_ref_args){
+		.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, 5);
+	sensor->ep_properties[1] = PROPERTY_ENTRY_U32_ARRAY_LEN(sensor->prop_names.data_lanes,
+								sensor->data_lanes,
+								sensor->ssdb.lanes);
+	sensor->ep_properties[2] = PROPERTY_ENTRY_REF_ARRAY(sensor->prop_names.remote_endpoint,
+							    sensor->local_ref);
+
+	sensor->cio2_properties[0] = PROPERTY_ENTRY_U32_ARRAY_LEN(sensor->prop_names.data_lanes,
+								  sensor->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, 6, "port%u", sensor->ssdb.link);
+	strcpy(sensor->node_names.port, "port0");
+	strcpy(sensor->node_names.endpoint, "endpoint0");
+}
+
+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_sensors(struct cio2_bridge *bridge)
+{
+	struct fwnode_handle *fwnode;
+	struct cio2_sensor *sensor;
+	struct acpi_device *adev;
+	unsigned int i;
+	int ret = 0;
+
+	for (i = 0; i < ARRAY_SIZE(cio2_supported_devices); i++) {
+		const char *this_device = cio2_supported_devices[i];
+
+		for_each_acpi_dev_match(adev, this_device, NULL, -1) {
+			if (!adev || !(adev->status.present && adev->status.enabled))
+				continue;
+
+			sensor = &bridge->sensors[bridge->n_sensors];
+			sensor->adev = adev;
+			strscpy(sensor->name, this_device, sizeof(sensor->name));
+
+			ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
+							   &sensor->ssdb,
+							   sizeof(sensor->ssdb));
+			if (ret < 0)
+				goto err_put_adev;
+
+			if (sensor->ssdb.lanes > 4) {
+				dev_err(&adev->dev,
+					"Number of lanes in SSDB is invalid\n");
+				goto err_put_adev;
+			}
+
+			cio2_bridge_create_fwnode_properties(sensor);
+			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(&bridge->cio2->dev,
+				 "Found supported sensor %s\n",
+				 acpi_dev_name(adev));
+
+			bridge->n_sensors++;
+		}
+	}
+
+	return ret;
+
+err_free_swnodes:
+	software_node_unregister_nodes(sensor->swnodes);
+err_put_adev:
+	acpi_dev_put(sensor->adev);
+
+	return ret;
+}
+
+int cio2_bridge_init(struct pci_dev *cio2)
+{
+	struct device *dev = &cio2->dev;
+	struct fwnode_handle *fwnode;
+	struct cio2_bridge *bridge;
+	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 = (const struct software_node){ bridge->cio2_node_name };
+	bridge->cio2 = pci_dev_get(cio2);
+
+	ret = software_node_register(&bridge->cio2_hid_node);
+	if (ret < 0) {
+		dev_err(dev, "Failed to register the CIO2 HID node\n");
+		goto err_put_cio2;
+	}
+
+	ret = cio2_bridge_connect_sensors(bridge);
+	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_put_cio2:
+	pci_dev_put(bridge->cio2);
+
+	kfree(bridge);
+	return ret;
+}
diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.h b/drivers/media/pci/intel/ipu3/cio2-bridge.h
new file mode 100644
index 000000000000..96f5c8a12be0
--- /dev/null
+++ b/drivers/media/pci/intel/ipu3/cio2-bridge.h
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Author: Dan Scally <djrscally@gmail.com> */
+#ifndef __CIO2_BRIDGE_H
+#define __CIO2_BRIDGE_H
+
+#include <linux/property.h>
+
+#define CIO2_HID				"INT343E"
+#define CIO2_NUM_PORTS			  4
+
+#define NODE_SENSOR(_HID, _PROPS)		\
+	((const struct software_node) {		\
+		.name = _HID,			\
+		.properties = _PROPS,		\
+	})
+
+#define NODE_PORT(_PORT, _SENSOR_NODE)		\
+	((const struct software_node) {		\
+		_PORT,				\
+		_SENSOR_NODE,			\
+	})
+
+#define NODE_ENDPOINT(_EP, _PORT, _PROPS)	\
+	((const struct software_node) {		\
+		_EP,				\
+		_PORT,				\
+		_PROPS,				\
+	})
+
+enum cio2_sensor_swnodes {
+	SWNODE_SENSOR_HID,
+	SWNODE_SENSOR_PORT,
+	SWNODE_SENSOR_ENDPOINT,
+	SWNODE_CIO2_PORT,
+	SWNODE_CIO2_ENDPOINT,
+	NR_OF_SENSOR_SWNODES
+};
+
+/* Data representation as it is in ACPI SSDB buffer */
+struct cio2_sensor_ssdb {
+	u8 version;
+	u8 sku;
+	u8 guid_csi2[16];
+	u8 devfunction;
+	u8 bus;
+	u32 dphylinkenfuses;
+	u32 clockdiv;
+	u8 link;
+	u8 lanes;
+	u32 csiparams[10];
+	u32 maxlanespeed;
+	u8 sensorcalibfileidx;
+	u8 sensorcalibfileidxInMBZ[3];
+	u8 romtype;
+	u8 vcmtype;
+	u8 platforminfo;
+	u8 platformsubinfo;
+	u8 flash;
+	u8 privacyled;
+	u8 degree;
+	u8 mipilinkdefined;
+	u32 mclkspeed;
+	u8 controllogicid;
+	u8 reserved1[3];
+	u8 mclkport;
+	u8 reserved2[13];
+} __packed__;
+
+struct cio2_property_names {
+	char clock_frequency[16];
+	char rotation[9];
+	char bus_type[9];
+	char data_lanes[11];
+	char remote_endpoint[16];
+};
+
+struct cio2_node_names {
+	char port[6];
+	char endpoint[10];
+	char remote_port[6];
+};
+
+struct cio2_sensor {
+	char name[ACPI_ID_LEN];
+	struct acpi_device *adev;
+
+	struct software_node swnodes[6];
+	struct cio2_node_names node_names;
+
+	u32 data_lanes[4];
+	struct cio2_sensor_ssdb ssdb;
+	struct cio2_property_names prop_names;
+	struct property_entry ep_properties[4];
+	struct property_entry dev_properties[3];
+	struct property_entry cio2_properties[3];
+	struct software_node_ref_args local_ref[1];
+	struct software_node_ref_args remote_ref[1];
+};
+
+struct cio2_bridge {
+	struct pci_dev *cio2;
+	char cio2_node_name[ACPI_ID_LEN];
+	struct software_node cio2_hid_node;
+	unsigned int n_sensors;
+	struct cio2_sensor sensors[CIO2_NUM_PORTS];
+};
+
+#endif
diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
index 36e354ecf71e..0d69b593e9f0 100644
--- a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
+++ b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
@@ -1702,6 +1702,22 @@ static void cio2_queues_exit(struct cio2_device *cio2)
 		cio2_queue_exit(cio2, &cio2->queue[i]);
 }
 
+static bool cio2_check_fwnode_graph(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *endpoint;
+
+	if (IS_ERR_OR_NULL(fwnode))
+		return false;
+
+	endpoint = fwnode_graph_get_next_endpoint(fwnode, NULL);
+	if (endpoint) {
+		fwnode_handle_put(endpoint);
+		return true;
+	}
+
+	return cio2_check_fwnode_graph(fwnode->secondary);
+}
+
 /**************** PCI interface ****************/
 
 static int cio2_pci_probe(struct pci_dev *pci_dev,
@@ -1715,6 +1731,17 @@ static int cio2_pci_probe(struct pci_dev *pci_dev,
 		return -ENOMEM;
 	cio2->pci_dev = pci_dev;
 
+	/*
+	 * On some platforms no connections to sensors are defined in firmware,
+	 * if the device has no endpoints then we can try to build those as
+	 * software_nodes parsed from SSDB.
+	 */
+	if (!cio2_check_fwnode_graph(dev_fwnode(&pci_dev->dev))) {
+		r = cio2_bridge_init(pci_dev);
+		if (r)
+			return r;
+	}
+
 	r = pcim_enable_device(pci_dev);
 	if (r) {
 		dev_err(&pci_dev->dev, "failed to enable device (%d)\n", r);
diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2.h b/drivers/media/pci/intel/ipu3/ipu3-cio2.h
index ccf0b85ae36f..520a27c9cdad 100644
--- a/drivers/media/pci/intel/ipu3/ipu3-cio2.h
+++ b/drivers/media/pci/intel/ipu3/ipu3-cio2.h
@@ -437,4 +437,10 @@ static inline struct cio2_queue *vb2q_to_cio2_queue(struct vb2_queue *vq)
 	return container_of(vq, struct cio2_queue, vbq);
 }
 
+#if IS_ENABLED(CONFIG_CIO2_BRIDGE)
+int cio2_bridge_init(struct pci_dev *cio2);
+#else
+int cio2_bridge_init(struct pci_dev *cio2) { return 0; }
+#endif
+
 #endif
-- 
2.25.1