Message-Id: <20200916213618.8003-1-djrscally@gmail.com>
Date:   Wed, 16 Sep 2020 22:36:18 +0100
From:   Daniel Scally <djrscally@...il.com>
To:     yong.zhi@...el.com, sakari.ailus@...ux.intel.com,
        bingbu.cao@...el.com, tian.shu.qiu@...el.com, mchehab@...nel.org,
        gregkh@...uxfoundation.org, davem@...emloft.net, robh@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        devel@...verdev.osuosl.org, jorhand@...ux.microsoft.com,
        kitakar@...il.com, kieran.bingham@...asonboard.com
Subject: [RFC PATCH] Add bridge driver to connect sensors to CIO2 device via software nodes on ACPI platforms

Currently on ACPI platforms, sensors that are intended to be connected to
a CIO2 device for use with the ipu3-cio2 driver lack the necessary
connection information in firmware. This patch adds a module to parse the
connection properties from the SSDB buffer in DSDT and build the connection
using software nodes.

The ipu3-cio2 driver itself is modified to insert the cio2-bridge module
after all sensors that have created a device link between themselves and
the CIO2 have probed. Sensors wishing to use this bridge will need to add
a device link between themselves and the CIO2 device as part of their own
.probe() call.

Suggested-by: Jordan Hand <jorhand@...ux.microsoft.com>

Signed-off-by: Daniel Scally <djrscally@...il.com>
---
This module's born out of efforts by the linux-surface github community
to get functioning webcams on Microsoft Surface and similar platforms. it
is dependent on this patch (which implements the software node graph family
of functions):

https://lore.kernel.org/linux-media/20200915232827.3416-1-djrscally@gmail.com/

I wanted to raise this as an RFC as although I don't think it's ready for
integration it has some things that I'd like feedback on, in particular the
method I chose to make the module be auto-inserted. A more ideal method would
have been to have the driver be an ACPI driver for the INT343E device, but each
of the the devices we've tested this on that dev has status 0 and so the module
won't bind to it. The device links method seems a little clunky, but does work,
and I think I have done the conditional processing correctly so that ipu3-cio2
continues to work on non-ACPI platforms.

 MAINTAINERS                              |   6 +
 drivers/media/pci/intel/ipu3/ipu3-cio2.c |  67 +++-
 drivers/staging/media/ipu3/Kconfig       |  15 +
 drivers/staging/media/ipu3/Makefile      |   1 +
 drivers/staging/media/ipu3/cio2-bridge.c | 448 +++++++++++++++++++++++
 5 files changed, 534 insertions(+), 3 deletions(-)
 create mode 100644 drivers/staging/media/ipu3/cio2-bridge.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b5cfab015bd6..55b0b9888bc0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9152,6 +9152,12 @@ S:	Maintained
 W:	http://www.adaptec.com/
 F:	drivers/scsi/ips*
 
+IPU3 CIO2 Bridge Driver
+M:	Daniel Scally <djrscally@...il.com>
+L:	linux-media@...r.kernel.org
+S:	Maintained
+F:	drivers/staging/media/ipu3/cio2-bridge.c
+
 IPVS
 M:	Wensong Zhang <wensong@...ux-vs.org>
 M:	Simon Horman <horms@...ge.net.au>
diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2.c b/drivers/media/pci/intel/ipu3/ipu3-cio2.c
index 92f5eadf2c99..fd941d2c7581 100644
--- a/drivers/media/pci/intel/ipu3/ipu3-cio2.c
+++ b/drivers/media/pci/intel/ipu3/ipu3-cio2.c
@@ -1719,6 +1719,59 @@ static void cio2_queues_exit(struct cio2_device *cio2)
 		cio2_queue_exit(cio2, &cio2->queue[i]);
 }
 
+static int cio2_probe_can_progress(struct pci_dev *pci_dev)
+{
+	void *sensor;
+
+	/*
+	 * On ACPI platforms, we need to probe _after_ sensors wishing to connect
+	 * to cio2 have added a device link. If there are no consumers yet, then
+	 * we need to defer. The .sync_state() callback will then be called after
+	 * all linked sensors have probed
+	 */
+
+	if (IS_ENABLED(CONFIG_ACPI)) {
+		sensor = (struct device *)list_first_entry_or_null(
+								&pci_dev->dev.links.consumers,
+								struct dev_links_info,
+								consumers);
+
+		if (!sensor)
+			return -EPROBE_DEFER;
+	}
+
+	return 0;
+}
+
+void cio2_sync_state(struct device *dev)
+{
+	struct cio2_device *cio2;
+	int ret = 0;
+
+	if (IS_ENABLED(CONFIG_ACPI)) {
+		cio2 = dev_get_drvdata(dev);
+
+		if (!cio2) {
+			dev_err(dev, "Failed to retrieve driver data\n");
+			return;
+		}
+
+		/* insert the bridge driver to connect sensors via software nodes */
+		ret = request_module("cio2-bridge");
+
+		if (ret)
+			dev_err(dev, "Failed to insert cio2-bridge\n");
+
+		ret = cio2_parse_firmware(cio2);
+
+		if (ret) {
+			v4l2_async_notifier_unregister(&cio2->notifier);
+			v4l2_async_notifier_cleanup(&cio2->notifier);
+			cio2_queues_exit(cio2);
+		}
+	}
+}
+
 /**************** PCI interface ****************/
 
 static int cio2_pci_config_setup(struct pci_dev *dev)
@@ -1746,6 +1799,11 @@ static int cio2_pci_probe(struct pci_dev *pci_dev,
 	void __iomem *const *iomap;
 	int r;
 
+	r = cio2_probe_can_progress(pci_dev);
+
+	if (r)
+		return -EPROBE_DEFER;
+
 	cio2 = devm_kzalloc(&pci_dev->dev, sizeof(*cio2), GFP_KERNEL);
 	if (!cio2)
 		return -ENOMEM;
@@ -1821,9 +1879,11 @@ static int cio2_pci_probe(struct pci_dev *pci_dev,
 	v4l2_async_notifier_init(&cio2->notifier);
 
 	/* Register notifier for subdevices we care */
-	r = cio2_parse_firmware(cio2);
-	if (r)
-		goto fail_clean_notifier;
+	if (!IS_ENABLED(CONFIG_ACPI)) {
+		r = cio2_parse_firmware(cio2);
+		if (r)
+			goto fail_clean_notifier;
+	}
 
 	r = devm_request_irq(&pci_dev->dev, pci_dev->irq, cio2_irq,
 			     IRQF_SHARED, CIO2_NAME, cio2);
@@ -2052,6 +2112,7 @@ static struct pci_driver cio2_pci_driver = {
 	.remove = cio2_pci_remove,
 	.driver = {
 		.pm = &cio2_pm_ops,
+		.sync_state = cio2_sync_state
 	},
 };
 
diff --git a/drivers/staging/media/ipu3/Kconfig b/drivers/staging/media/ipu3/Kconfig
index 3e9640523e50..08842fd8c0da 100644
--- a/drivers/staging/media/ipu3/Kconfig
+++ b/drivers/staging/media/ipu3/Kconfig
@@ -14,3 +14,18 @@ config VIDEO_IPU3_IMGU
 
 	  Say Y or M here if you have a Skylake/Kaby Lake SoC with a MIPI
 	  camera. The module will be called ipu3-imgu.
+
+config VIDEO_CIO2_BRIDGE
+	tristate "IPU3 CIO2 Sensor Bridge Driver"
+	depends on PCI && VIDEO_V4L2
+	depends on ACPI
+	depends on X86
+	help
+	  This module provides a bridge connecting sensors (I.E. cameras) to
+	  the CIO2 device infrastructure via software nodes built from information
+	  parsed from the SSDB buffer.
+
+	  Say Y or M here if your platform's cameras use IPU3 with connections
+	  that should be defined in ACPI. The module will be called cio2-bridge.
+
+	  If in doubt, say N here.
\ No newline at end of file
diff --git a/drivers/staging/media/ipu3/Makefile b/drivers/staging/media/ipu3/Makefile
index 9def80ef28f3..12dff56dbb9e 100644
--- a/drivers/staging/media/ipu3/Makefile
+++ b/drivers/staging/media/ipu3/Makefile
@@ -10,3 +10,4 @@ ipu3-imgu-objs += \
 		ipu3-css.o ipu3-v4l2.o ipu3.o
 
 obj-$(CONFIG_VIDEO_IPU3_IMGU) += ipu3-imgu.o
+obj-$(CONFIG_VIDEO_CIO2_BRIDGE) += cio2-bridge.o
\ No newline at end of file
diff --git a/drivers/staging/media/ipu3/cio2-bridge.c b/drivers/staging/media/ipu3/cio2-bridge.c
new file mode 100644
index 000000000000..5115aeeb35a1
--- /dev/null
+++ b/drivers/staging/media/ipu3/cio2-bridge.c
@@ -0,0 +1,448 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/acpi.h>
+#include <acpi/acpi_bus.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <media/v4l2-subdev.h>
+
+#include <linux/fwnode.h>
+#include <linux/kref.h>
+
+static void cio2_bridge_exit(void);
+static int cio2_bridge_init(void);
+
+#define MAX_CONNECTED_DEVICES			4
+#define SWNODE_SENSOR_HID			0
+#define SWNODE_SENSOR_PORT			1
+#define SWNODE_SENSOR_ENDPOINT			2
+#define SWNODE_CIO2_PORT			3
+#define SWNODE_CIO2_ENDPOINT			4
+#define SWNODE_NULL_TERMINATOR			5
+
+#define CIO2_HID				"INT343E"
+#define CIO2_PCI_ID				0x9d32
+
+#define ENDPOINT_SENSOR				0
+#define ENDPOINT_CIO2				1
+
+#define NODE_HID(_HID)				\
+((const struct software_node) {			\
+	_HID,					\
+})
+
+#define NODE_PORT(_PORT, _HID_NODE)		\
+((const struct software_node) {			\
+	_PORT,					\
+	_HID_NODE,				\
+})
+
+#define NODE_ENDPOINT(_EP, _PORT, _PROPS)	\
+((const struct software_node) {			\
+	_EP,					\
+	_PORT,					\
+	_PROPS,					\
+})
+
+#define PROPERTY_ENTRY_NULL			\
+((const struct property_entry) { })
+#define SOFTWARE_NODE_NULL			\
+((const struct software_node) { })
+
+/*
+ * Extend this array with ACPI Hardware ID's of devices known to be
+ * working
+ */
+
+static char *supported_devices[] = {
+	"INT33BE",
+	"OVTI2680",
+	"OVTI5648",
+};
+
+/*
+ * software_node needs const char * names. Can't snprintf a const char *,
+ * so instead we need an array of them and use the port num from SSDB as
+ * an index.
+ */
+
+const char *port_names[] = {
+	"port0", "port1", "port2", "port3", "port4",
+	"port5", "port6", "port7", "port8", "port9"
+};
+
+struct software_node cio2_hid_node = { CIO2_HID, };
+
+struct sensor {
+	struct device *dev;
+	struct software_node swnodes[5];
+	struct property_entry sensor_props[6];
+	struct property_entry cio2_props[3];
+	struct fwnode_handle *fwnode;
+};
+
+struct cio2_bridge {
+	int n_sensors;
+	struct sensor sensors[MAX_CONNECTED_DEVICES];
+	struct pci_dev *cio2;
+	struct fwnode_handle *cio2_fwnode;
+};
+
+struct cio2_bridge bridge = { 0, };
+
+static const struct property_entry remote_endpoints[] = {
+	PROPERTY_ENTRY_REF("remote-endpoint", /* Sensor 0, Sensor Property */
+			   &bridge.sensors[0].swnodes[SWNODE_CIO2_ENDPOINT]),
+	PROPERTY_ENTRY_REF("remote-endpoint", /* Sensor 0, CIO2 Property */
+			   &bridge.sensors[0].swnodes[SWNODE_SENSOR_ENDPOINT]),
+	PROPERTY_ENTRY_REF("remote-endpoint",
+			   &bridge.sensors[1].swnodes[SWNODE_CIO2_ENDPOINT]),
+	PROPERTY_ENTRY_REF("remote-endpoint",
+			   &bridge.sensors[1].swnodes[SWNODE_SENSOR_ENDPOINT]),
+	PROPERTY_ENTRY_REF("remote-endpoint",
+			   &bridge.sensors[2].swnodes[SWNODE_CIO2_ENDPOINT]),
+	PROPERTY_ENTRY_REF("remote-endpoint",
+			   &bridge.sensors[2].swnodes[SWNODE_SENSOR_ENDPOINT]),
+	PROPERTY_ENTRY_REF("remote-endpoint",
+			   &bridge.sensors[3].swnodes[SWNODE_CIO2_ENDPOINT]),
+	PROPERTY_ENTRY_REF("remote-endpoint",
+			   &bridge.sensors[3].swnodes[SWNODE_SENSOR_ENDPOINT]),
+	{ }
+};
+
+/* Data representation as it is in ACPI SSDB buffer */
+struct sensor_bios_data_packed {
+	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];
+} __attribute__((__packed__));
+
+/* Fields needed by bridge driver */
+struct sensor_bios_data {
+	struct device *dev;
+	u8 link;
+	u8 lanes;
+	u32 mclkspeed;
+};
+
+static int read_acpi_block(struct device *dev, char *id, void *data, u32 size)
+{
+	union acpi_object *obj;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_handle *dev_handle = ACPI_HANDLE(dev);
+	int status;
+	u32 buffer_length;
+
+	status = acpi_evaluate_object(dev_handle, id, NULL, &buffer);
+	if (!ACPI_SUCCESS(status))
+		return -ENODEV;
+
+	obj = (union acpi_object *)buffer.pointer;
+	if (!obj || obj->type != ACPI_TYPE_BUFFER) {
+		dev_err(dev, "Could't read acpi buffer\n");
+		status = -ENODEV;
+		goto err;
+	}
+
+	if (obj->buffer.length > size) {
+		dev_err(dev, "Given buffer is too small\n");
+		status = -ENODEV;
+		goto err;
+	}
+
+	memcpy(data, obj->buffer.pointer, min(size, obj->buffer.length));
+	buffer_length = obj->buffer.length;
+	kfree(buffer.pointer);
+
+	return buffer_length;
+err:
+	kfree(buffer.pointer);
+	return status;
+}
+
+static int get_acpi_ssdb_sensor_data(struct device *dev,
+				     struct sensor_bios_data *sensor)
+{
+	struct sensor_bios_data_packed sensor_data;
+	int ret = read_acpi_block(dev, "SSDB", &sensor_data,
+				  sizeof(sensor_data));
+
+	if (ret < 0) {
+		dev_err(dev, "Failed to fetch SSDB data\n");
+		return ret;
+	}
+
+	sensor->link = sensor_data.link;
+	sensor->lanes = sensor_data.lanes;
+	sensor->mclkspeed = sensor_data.mclkspeed;
+
+	return 0;
+}
+
+static int create_endpoint_properties(struct device *dev,
+				      struct sensor_bios_data *ssdb,
+				      struct property_entry *sensor_props,
+				      struct property_entry *cio2_props)
+{
+		u32 *data_lanes;
+		int i;
+
+		data_lanes = devm_kmalloc(dev, sizeof(u32) * (int)ssdb->lanes,
+					  GFP_KERNEL);
+
+		if (!data_lanes) {
+			dev_err(dev,
+				"Couldn't allocate memory for data lanes array\n");
+			return -ENOMEM;
+		}
+
+		for (i = 0; i < (int)ssdb->lanes; i++)
+			data_lanes[i] = (u32)i + 1;
+
+		sensor_props[0] = PROPERTY_ENTRY_U32("clock-frequency",
+						     ssdb->mclkspeed);
+		sensor_props[1] = PROPERTY_ENTRY_U32("bus-type", 5);
+		sensor_props[2] = PROPERTY_ENTRY_U32("clock-lanes", 0);
+		sensor_props[3] = PROPERTY_ENTRY_U32_ARRAY_LEN("data-lanes",
+							       data_lanes,
+							       (int)ssdb->lanes);
+		sensor_props[4] = remote_endpoints[(bridge.n_sensors * 2) + ENDPOINT_SENSOR];
+		sensor_props[5] = PROPERTY_ENTRY_NULL;
+
+		cio2_props[0] = PROPERTY_ENTRY_U32_ARRAY_LEN("data-lanes",
+							     data_lanes,
+							     (int)ssdb->lanes);
+		cio2_props[1] = remote_endpoints[(bridge.n_sensors * 2) + ENDPOINT_CIO2];
+		cio2_props[2] = PROPERTY_ENTRY_NULL;
+
+		return 0;
+}
+
+static int connect_supported_devices(void)
+{
+	struct acpi_device *adev;
+	struct device *dev;
+	struct sensor_bios_data ssdb;
+	struct sensor *sensor;
+	struct property_entry *sensor_props;
+	struct property_entry *cio2_props;
+	struct fwnode_handle *fwnode;
+	struct software_node *nodes;
+	struct v4l2_subdev *sd;
+	int i, ret;
+
+	for (i = 0; i < ARRAY_SIZE(supported_devices); i++) {
+		adev = acpi_dev_get_first_match_dev(supported_devices[i],
+						    NULL, -1);
+
+		if (!adev)
+			continue;
+
+		dev = bus_find_device_by_acpi_dev(&i2c_bus_type, adev);
+
+		if (!dev) {
+			pr_info("ACPI match for %s, but it has no i2c device\n",
+				supported_devices[i]);
+			continue;
+		}
+
+		if (!dev->driver_data) {
+			pr_info("ACPI match for %s, but it has no driver\n",
+				supported_devices[i]);
+			continue;
+		} else {
+			pr_info("Found supported device %s\n",
+				supported_devices[i]);
+		}
+
+		sensor = &bridge.sensors[bridge.n_sensors];
+		/*
+		 * Store sensor's existing fwnode so that it can be restored if
+		 * this module is removed.
+		 */
+		sensor->fwnode = fwnode_handle_get(dev->fwnode);
+
+		get_acpi_ssdb_sensor_data(dev, &ssdb);
+
+		nodes = sensor->swnodes;
+		sensor_props = sensor->sensor_props;
+		cio2_props = sensor->cio2_props;
+		fwnode = sensor->fwnode;
+
+		ret = create_endpoint_properties(dev, &ssdb, sensor_props,
+						 cio2_props);
+
+		if (ret)
+			return ret;
+
+		/* build the software nodes */
+
+		nodes[SWNODE_SENSOR_HID] = NODE_HID(supported_devices[i]);
+		nodes[SWNODE_SENSOR_PORT] = NODE_PORT("port0",
+						      &nodes[SWNODE_SENSOR_HID]);
+		nodes[SWNODE_SENSOR_ENDPOINT] = NODE_ENDPOINT("endpoint0",
+							      &nodes[SWNODE_SENSOR_PORT],
+							      sensor_props);
+		nodes[SWNODE_CIO2_PORT] = NODE_PORT(port_names[(int)ssdb.link],
+						    &cio2_hid_node);
+		nodes[SWNODE_CIO2_ENDPOINT] = NODE_ENDPOINT("endpoint0",
+							    &nodes[SWNODE_CIO2_PORT],
+							    cio2_props);
+		nodes[SWNODE_NULL_TERMINATOR]   = SOFTWARE_NODE_NULL;
+
+		ret = software_node_register_nodes(nodes);
+		if (ret) {
+			dev_err(dev,
+				"Failed to register software nodes for %s\n",
+				supported_devices[i]);
+			return ret;
+		}
+
+		fwnode = software_node_fwnode(&nodes[SWNODE_SENSOR_HID]);
+		if (!fwnode) {
+			dev_err(dev,
+				"Failed to get software node for %s\n",
+				supported_devices[i]);
+			return ret;
+		}
+
+		fwnode->secondary = ERR_PTR(-ENODEV);
+		dev->fwnode = fwnode;
+
+		/*
+		 * The device should by this point has driver_data set to an
+		 * instance of struct v4l2_subdev; set the fwnode for that too.
+		 */
+
+		sd = dev_get_drvdata(dev);
+		sd->fwnode = fwnode;
+
+		sensor->dev = dev;
+		bridge.n_sensors++;
+	}
+
+	return 0;
+}
+
+static int cio2_bridge_init(void)
+{
+	struct fwnode_handle *fwnode;
+	int ret;
+
+	ret = software_node_register(&cio2_hid_node);
+
+	if (ret < 0) {
+		pr_err("Failed to register the CIO2 HID node\n");
+		return -EINVAL;
+	}
+
+	ret = connect_supported_devices();
+
+	if ((ret < 0) || (bridge.n_sensors <= 0)) {
+		pr_err("cio2_bridge: Failed to connect any devices\n");
+		goto out;
+	} else {
+		pr_info("Found %d supported devices\n", bridge.n_sensors);
+	}
+
+	bridge.cio2 = pci_get_device(PCI_VENDOR_ID_INTEL, CIO2_PCI_ID, NULL);
+	if (!bridge.cio2) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	fwnode = software_node_fwnode(&cio2_hid_node);
+	if (!fwnode) {
+		pr_err("Error getting fwnode from cio2 software_node\n");
+		ret = -ENODEV;
+		goto out;
+	}
+
+	/*
+	 * We store the pci_dev's existing fwnode, beccause in the event we
+	 * want to reload (I.E. rmmod and insmod) this module we need to give
+	 * the device its original fwnode back to prevent problems down the
+	 * line
+	 */
+
+	bridge.cio2_fwnode = fwnode_handle_get(bridge.cio2->dev.fwnode);
+
+	fwnode->secondary = ERR_PTR(-ENODEV);
+	bridge.cio2->dev.fwnode = fwnode;
+
+	return 0;
+out:
+	cio2_bridge_exit();
+	return ret;
+}
+
+static int cio2_bridge_unregister_sensors(void)
+{
+	int i, j;
+	struct sensor *sensor;
+
+	for (i = 0; i < bridge.n_sensors; i++) {
+		sensor = &bridge.sensors[i];
+
+		/* give the sensor its original fwnode back */
+		sensor->dev->fwnode = sensor->fwnode;
+		fwnode_handle_put(sensor->fwnode);
+		put_device(sensor->dev);
+
+		for (j = 4; j >= 0; j--)
+			software_node_unregister(&sensor->swnodes[j]);
+	}
+
+	return 0;
+}
+
+static void cio2_bridge_exit(void)
+{
+	int ret;
+
+	/* Give the pci_dev its original fwnode back */
+	if (bridge.cio2) {
+		bridge.cio2->dev.fwnode = bridge.cio2_fwnode;
+		fwnode_handle_put(bridge.cio2_fwnode);
+		pci_dev_put(bridge.cio2);
+	}
+
+	ret = cio2_bridge_unregister_sensors();
+
+	if (ret)
+		pr_err("An error occurred unregistering the sensors\n");
+
+	software_node_unregister(&cio2_hid_node);
+}
+
+module_init(cio2_bridge_init);
+module_exit(cio2_bridge_exit);
+
+MODULE_DESCRIPTION("A bridge driver to connect sensors to CIO2 infrastructure.");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("acpi*:INT343E:*");
-- 
2.17.1

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