[patch 11/32] greybus: camera driver

[Greg KH]

This driver implements the Greybus camera protocol.

Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/greybus/camera.c    | 1400 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/greybus/gb-camera.h |  127 +++
 2 files changed, 1527 insertions(+)

--- /dev/null
+++ b/drivers/greybus/camera.c
@@ -0,0 +1,1400 @@
+/*
+ * Greybus Camera protocol driver.
+ *
+ * Copyright 2015 Google Inc.
+ * Copyright 2015 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+
+#include "gb-camera.h"
+#include "greybus.h"
+#include "greybus_protocols.h"
+
+enum gb_camera_debugs_buffer_id {
+	GB_CAMERA_DEBUGFS_BUFFER_CAPABILITIES,
+	GB_CAMERA_DEBUGFS_BUFFER_STREAMS,
+	GB_CAMERA_DEBUGFS_BUFFER_CAPTURE,
+	GB_CAMERA_DEBUGFS_BUFFER_FLUSH,
+	GB_CAMERA_DEBUGFS_BUFFER_MAX,
+};
+
+struct gb_camera_debugfs_buffer {
+	char data[PAGE_SIZE];
+	size_t length;
+};
+
+enum gb_camera_state {
+	GB_CAMERA_STATE_UNCONFIGURED,
+	GB_CAMERA_STATE_CONFIGURED,
+};
+
+/**
+ * struct gb_camera - A Greybus Camera Device
+ * @connection: the greybus connection for camera management
+ * @data_connection: the greybus connection for camera data
+ * @data_cport_id: the data CPort ID on the module side
+ * @mutex: protects the connection and state fields
+ * @state: the current module state
+ * @debugfs: debugfs entries for camera protocol operations testing
+ * @module: Greybus camera module registered to HOST processor.
+ */
+struct gb_camera {
+	struct gb_bundle *bundle;
+	struct gb_connection *connection;
+	struct gb_connection *data_connection;
+	u16 data_cport_id;
+
+	struct mutex mutex;
+	enum gb_camera_state state;
+
+	struct {
+		struct dentry *root;
+		struct gb_camera_debugfs_buffer *buffers;
+	} debugfs;
+
+	struct gb_camera_module module;
+};
+
+struct gb_camera_stream_config {
+	unsigned int width;
+	unsigned int height;
+	unsigned int format;
+	unsigned int vc;
+	unsigned int dt[2];
+	unsigned int max_size;
+};
+
+struct gb_camera_fmt_info {
+	enum v4l2_mbus_pixelcode mbus_code;
+	unsigned int gb_format;
+	unsigned int bpp;
+};
+
+/* GB format to media code map */
+static const struct gb_camera_fmt_info gb_fmt_info[] = {
+	{
+		.mbus_code = V4L2_MBUS_FMT_UYVY8_1X16,
+		.gb_format = 0x01,
+		.bpp	   = 16,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_NV12_1x8,
+		.gb_format = 0x12,
+		.bpp	   = 12,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_NV21_1x8,
+		.gb_format = 0x13,
+		.bpp	   = 12,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_YU12_1x8,
+		.gb_format = 0x16,
+		.bpp	   = 12,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_YV12_1x8,
+		.gb_format = 0x17,
+		.bpp	   = 12,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_JPEG_1X8,
+		.gb_format = 0x40,
+		.bpp	   = 0,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_GB_CAM_METADATA_1X8,
+		.gb_format = 0x41,
+		.bpp	   = 0,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_GB_CAM_DEBUG_DATA_1X8,
+		.gb_format = 0x42,
+		.bpp	   = 0,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_SBGGR10_1X10,
+		.gb_format = 0x80,
+		.bpp	   = 10,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_SGBRG10_1X10,
+		.gb_format = 0x81,
+		.bpp	   = 10,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_SGRBG10_1X10,
+		.gb_format = 0x82,
+		.bpp	   = 10,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_SRGGB10_1X10,
+		.gb_format = 0x83,
+		.bpp	   = 10,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_SBGGR12_1X12,
+		.gb_format = 0x84,
+		.bpp	   = 12,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_SGBRG12_1X12,
+		.gb_format = 0x85,
+		.bpp	   = 12,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_SGRBG12_1X12,
+		.gb_format = 0x86,
+		.bpp	   = 12,
+	},
+	{
+		.mbus_code = V4L2_MBUS_FMT_SRGGB12_1X12,
+		.gb_format = 0x87,
+		.bpp	   = 12,
+	},
+};
+
+static const struct gb_camera_fmt_info *gb_camera_get_format_info(u16 gb_fmt)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gb_fmt_info); i++) {
+		if (gb_fmt_info[i].gb_format == gb_fmt)
+			return &gb_fmt_info[i];
+	}
+
+	return NULL;
+}
+
+#define ES2_APB_CDSI0_CPORT		16
+#define ES2_APB_CDSI1_CPORT		17
+
+#define GB_CAMERA_MAX_SETTINGS_SIZE	8192
+
+#define gcam_dbg(gcam, format...)	dev_dbg(&gcam->bundle->dev, format)
+#define gcam_info(gcam, format...)	dev_info(&gcam->bundle->dev, format)
+#define gcam_err(gcam, format...)	dev_err(&gcam->bundle->dev, format)
+
+static int gb_camera_operation_sync_flags(struct gb_connection *connection,
+					  int type, unsigned int flags,
+					  void *request, size_t request_size,
+					  void *response, size_t *response_size)
+{
+	struct gb_operation *operation;
+	int ret;
+
+	operation = gb_operation_create_flags(connection, type, request_size,
+					      *response_size, flags,
+					      GFP_KERNEL);
+	if (!operation)
+		return  -ENOMEM;
+
+	if (request_size)
+		memcpy(operation->request->payload, request, request_size);
+
+	ret = gb_operation_request_send_sync(operation);
+	if (ret) {
+		dev_err(&connection->hd->dev,
+			"%s: synchronous operation of type 0x%02x failed: %d\n",
+			connection->name, type, ret);
+	} else {
+		*response_size = operation->response->payload_size;
+
+		if (operation->response->payload_size)
+			memcpy(response, operation->response->payload,
+			       operation->response->payload_size);
+	}
+
+	gb_operation_put(operation);
+
+	return ret;
+}
+
+static int gb_camera_get_max_pkt_size(struct gb_camera *gcam,
+		struct gb_camera_configure_streams_response *resp)
+{
+	unsigned int max_pkt_size = 0;
+	unsigned int i;
+
+	for (i = 0; i < resp->num_streams; i++) {
+		struct gb_camera_stream_config_response *cfg = &resp->config[i];
+		const struct gb_camera_fmt_info *fmt_info;
+		unsigned int pkt_size;
+
+		fmt_info = gb_camera_get_format_info(cfg->format);
+		if (!fmt_info) {
+			gcam_err(gcam, "unsupported greybus image format: %d\n",
+				 cfg->format);
+			return -EIO;
+		}
+
+		if (fmt_info->bpp == 0) {
+			pkt_size = le32_to_cpu(cfg->max_pkt_size);
+
+			if (pkt_size == 0) {
+				gcam_err(gcam,
+					 "Stream %u: invalid zero maximum packet size\n",
+					 i);
+				return -EIO;
+			}
+		} else {
+			pkt_size = le16_to_cpu(cfg->width) * fmt_info->bpp / 8;
+
+			if (pkt_size != le32_to_cpu(cfg->max_pkt_size)) {
+				gcam_err(gcam,
+					 "Stream %u: maximum packet size mismatch (%u/%u)\n",
+					 i, pkt_size, cfg->max_pkt_size);
+				return -EIO;
+			}
+		}
+
+		max_pkt_size = max(pkt_size, max_pkt_size);
+	}
+
+	return max_pkt_size;
+}
+
+/*
+ * Validate the stream configuration response verifying padding is correctly
+ * set and the returned number of streams is supported
+ */
+static const int gb_camera_configure_streams_validate_response(
+		struct gb_camera *gcam,
+		struct gb_camera_configure_streams_response *resp,
+		unsigned int nstreams)
+{
+	unsigned int i;
+
+	/* Validate the returned response structure */
+	if (resp->padding[0] || resp->padding[1]) {
+		gcam_err(gcam, "response padding != 0\n");
+		return -EIO;
+	}
+
+	if (resp->num_streams > nstreams) {
+		gcam_err(gcam, "got #streams %u > request %u\n",
+			 resp->num_streams, nstreams);
+		return -EIO;
+	}
+
+	for (i = 0; i < resp->num_streams; i++) {
+		struct gb_camera_stream_config_response *cfg = &resp->config[i];
+		if (cfg->padding) {
+			gcam_err(gcam, "stream #%u padding != 0\n", i);
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+/* -----------------------------------------------------------------------------
+ * Hardware Configuration
+ */
+
+static int gb_camera_set_intf_power_mode(struct gb_camera *gcam, u8 intf_id,
+					 bool hs)
+{
+	struct gb_svc *svc = gcam->connection->hd->svc;
+	int ret;
+
+	if (hs)
+		ret = gb_svc_intf_set_power_mode(svc, intf_id,
+						 GB_SVC_UNIPRO_HS_SERIES_A,
+						 GB_SVC_UNIPRO_FAST_MODE, 2, 2,
+						 GB_SVC_SMALL_AMPLITUDE,
+						 GB_SVC_NO_DE_EMPHASIS,
+						 GB_SVC_UNIPRO_FAST_MODE, 2, 2,
+						 GB_SVC_PWRM_RXTERMINATION |
+						 GB_SVC_PWRM_TXTERMINATION, 0,
+						 NULL, NULL);
+	else
+		ret = gb_svc_intf_set_power_mode(svc, intf_id,
+						 GB_SVC_UNIPRO_HS_SERIES_A,
+						 GB_SVC_UNIPRO_SLOW_AUTO_MODE,
+						 2, 1,
+						 GB_SVC_SMALL_AMPLITUDE,
+						 GB_SVC_NO_DE_EMPHASIS,
+						 GB_SVC_UNIPRO_SLOW_AUTO_MODE,
+						 2, 1,
+						 0, 0,
+						 NULL, NULL);
+
+	return ret;
+}
+
+static int gb_camera_set_power_mode(struct gb_camera *gcam, bool hs)
+{
+	struct gb_interface *intf = gcam->connection->intf;
+	struct gb_svc *svc = gcam->connection->hd->svc;
+	int ret;
+
+	ret = gb_camera_set_intf_power_mode(gcam, intf->interface_id, hs);
+	if (ret < 0) {
+		gcam_err(gcam, "failed to set module interface to %s (%d)\n",
+			 hs ? "HS" : "PWM", ret);
+		return ret;
+	}
+
+	ret = gb_camera_set_intf_power_mode(gcam, svc->ap_intf_id, hs);
+	if (ret < 0) {
+		gb_camera_set_intf_power_mode(gcam, intf->interface_id, !hs);
+		gcam_err(gcam, "failed to set AP interface to %s (%d)\n",
+			 hs ? "HS" : "PWM", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+struct ap_csi_config_request {
+	__u8 csi_id;
+	__u8 flags;
+#define GB_CAMERA_CSI_FLAG_CLOCK_CONTINUOUS 0x01
+	__u8 num_lanes;
+	__u8 padding;
+	__le32 csi_clk_freq;
+	__le32 max_pkt_size;
+} __packed;
+
+/*
+ * TODO: Compute the number of lanes dynamically based on bandwidth
+ * requirements.
+ */
+#define GB_CAMERA_CSI_NUM_DATA_LANES		4
+
+#define GB_CAMERA_CSI_CLK_FREQ_MAX		999000000U
+#define GB_CAMERA_CSI_CLK_FREQ_MIN		100000000U
+#define GB_CAMERA_CSI_CLK_FREQ_MARGIN		150000000U
+
+static int gb_camera_setup_data_connection(struct gb_camera *gcam,
+		struct gb_camera_configure_streams_response *resp,
+		struct gb_camera_csi_params *csi_params)
+{
+	struct ap_csi_config_request csi_cfg;
+	struct gb_connection *conn;
+	unsigned int clk_freq;
+	int ret;
+
+	/*
+	 * Create the data connection between the camera module data CPort and
+	 * APB CDSI1. The CDSI1 CPort ID is hardcoded by the ES2 bridge.
+	 */
+	conn = gb_connection_create_offloaded(gcam->bundle, gcam->data_cport_id,
+					      GB_CONNECTION_FLAG_NO_FLOWCTRL |
+					      GB_CONNECTION_FLAG_CDSI1);
+	if (IS_ERR(conn))
+		return PTR_ERR(conn);
+
+	gcam->data_connection = conn;
+	gb_connection_set_data(conn, gcam);
+
+	ret = gb_connection_enable(conn);
+	if (ret)
+		goto error_conn_destroy;
+
+	/* Set the UniPro link to high speed mode. */
+	ret = gb_camera_set_power_mode(gcam, true);
+	if (ret < 0)
+		goto error_conn_disable;
+
+	/*
+	 * Configure the APB-A CSI-2 transmitter.
+	 *
+	 * Hardcode the number of lanes to 4 and compute the bus clock frequency
+	 * based on the module bandwidth requirements with a safety margin.
+	 */
+	memset(&csi_cfg, 0, sizeof(csi_cfg));
+	csi_cfg.csi_id = 1;
+	csi_cfg.flags = 0;
+	csi_cfg.num_lanes = GB_CAMERA_CSI_NUM_DATA_LANES;
+
+	clk_freq = resp->data_rate / 2 / GB_CAMERA_CSI_NUM_DATA_LANES;
+	clk_freq = clamp(clk_freq + GB_CAMERA_CSI_CLK_FREQ_MARGIN,
+			 GB_CAMERA_CSI_CLK_FREQ_MIN,
+			 GB_CAMERA_CSI_CLK_FREQ_MAX);
+	csi_cfg.csi_clk_freq = clk_freq;
+
+	ret = gb_camera_get_max_pkt_size(gcam, resp);
+	if (ret < 0) {
+		ret = -EIO;
+		goto error_power;
+	}
+	csi_cfg.max_pkt_size = ret;
+
+	ret = gb_hd_output(gcam->connection->hd, &csi_cfg,
+			   sizeof(csi_cfg),
+			   GB_APB_REQUEST_CSI_TX_CONTROL, false);
+	if (ret < 0) {
+		gcam_err(gcam, "failed to start the CSI transmitter\n");
+		goto error_power;
+	}
+
+	if (csi_params) {
+		csi_params->clk_freq = csi_cfg.csi_clk_freq;
+		csi_params->num_lanes = csi_cfg.num_lanes;
+	}
+
+	return 0;
+
+error_power:
+	gb_camera_set_power_mode(gcam, false);
+error_conn_disable:
+	gb_connection_disable(gcam->data_connection);
+error_conn_destroy:
+	gb_connection_destroy(gcam->data_connection);
+	gcam->data_connection = NULL;
+	return ret;
+}
+
+static void gb_camera_teardown_data_connection(struct gb_camera *gcam)
+{
+	struct ap_csi_config_request csi_cfg;
+	int ret;
+
+	/* Stop the APB1 CSI transmitter. */
+	memset(&csi_cfg, 0, sizeof(csi_cfg));
+	csi_cfg.csi_id = 1;
+
+	ret = gb_hd_output(gcam->connection->hd, &csi_cfg,
+			   sizeof(csi_cfg),
+			   GB_APB_REQUEST_CSI_TX_CONTROL, false);
+
+	if (ret < 0)
+		gcam_err(gcam, "failed to stop the CSI transmitter\n");
+
+	/* Set the UniPro link to low speed mode. */
+	gb_camera_set_power_mode(gcam, false);
+
+	/* Destroy the data connection. */
+	gb_connection_disable(gcam->data_connection);
+	gb_connection_destroy(gcam->data_connection);
+	gcam->data_connection = NULL;
+}
+
+/* -----------------------------------------------------------------------------
+ * Camera Protocol Operations
+ */
+
+static int gb_camera_capabilities(struct gb_camera *gcam,
+				  u8 *capabilities, size_t *size)
+{
+	int ret;
+
+	ret = gb_pm_runtime_get_sync(gcam->bundle);
+	if (ret)
+		return ret;
+
+	mutex_lock(&gcam->mutex);
+
+	if (!gcam->connection) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	ret = gb_camera_operation_sync_flags(gcam->connection,
+					     GB_CAMERA_TYPE_CAPABILITIES,
+					     GB_OPERATION_FLAG_SHORT_RESPONSE,
+					     NULL, 0,
+					     (void *)capabilities, size);
+	if (ret)
+		gcam_err(gcam, "failed to retrieve capabilities: %d\n", ret);
+
+done:
+	mutex_unlock(&gcam->mutex);
+
+	gb_pm_runtime_put_autosuspend(gcam->bundle);
+
+	return ret;
+}
+
+static int gb_camera_configure_streams(struct gb_camera *gcam,
+				       unsigned int *num_streams,
+				       unsigned int *flags,
+				       struct gb_camera_stream_config *streams,
+				       struct gb_camera_csi_params *csi_params)
+{
+	struct gb_camera_configure_streams_request *req;
+	struct gb_camera_configure_streams_response *resp;
+	unsigned int nstreams = *num_streams;
+	unsigned int i;
+	size_t req_size;
+	size_t resp_size;
+	int ret;
+
+	if (nstreams > GB_CAMERA_MAX_STREAMS)
+		return -EINVAL;
+
+	req_size = sizeof(*req) + nstreams * sizeof(req->config[0]);
+	resp_size = sizeof(*resp) + nstreams * sizeof(resp->config[0]);
+
+	req = kmalloc(req_size, GFP_KERNEL);
+	resp = kmalloc(resp_size, GFP_KERNEL);
+	if (!req || !resp) {
+		kfree(req);
+		kfree(resp);
+		return -ENOMEM;
+	}
+
+	req->num_streams = nstreams;
+	req->flags = *flags;
+	req->padding = 0;
+
+	for (i = 0; i < nstreams; ++i) {
+		struct gb_camera_stream_config_request *cfg = &req->config[i];
+
+		cfg->width = cpu_to_le16(streams[i].width);
+		cfg->height = cpu_to_le16(streams[i].height);
+		cfg->format = cpu_to_le16(streams[i].format);
+		cfg->padding = 0;
+	}
+
+	mutex_lock(&gcam->mutex);
+
+	ret = gb_pm_runtime_get_sync(gcam->bundle);
+	if (ret)
+		goto done_skip_pm_put;
+
+	if (!gcam->connection) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	ret = gb_camera_operation_sync_flags(gcam->connection,
+					     GB_CAMERA_TYPE_CONFIGURE_STREAMS,
+					     GB_OPERATION_FLAG_SHORT_RESPONSE,
+					     req, req_size,
+					     resp, &resp_size);
+	if (ret < 0)
+		goto done;
+
+	ret = gb_camera_configure_streams_validate_response(gcam, resp,
+							    nstreams);
+	if (ret < 0)
+		goto done;
+
+	*flags = resp->flags;
+	*num_streams = resp->num_streams;
+
+	for (i = 0; i < resp->num_streams; ++i) {
+		struct gb_camera_stream_config_response *cfg = &resp->config[i];
+
+		streams[i].width = le16_to_cpu(cfg->width);
+		streams[i].height = le16_to_cpu(cfg->height);
+		streams[i].format = le16_to_cpu(cfg->format);
+		streams[i].vc = cfg->virtual_channel;
+		streams[i].dt[0] = cfg->data_type[0];
+		streams[i].dt[1] = cfg->data_type[1];
+		streams[i].max_size = le32_to_cpu(cfg->max_size);
+	}
+
+	if ((resp->flags & GB_CAMERA_CONFIGURE_STREAMS_ADJUSTED) ||
+	    (req->flags & GB_CAMERA_CONFIGURE_STREAMS_TEST_ONLY))
+		goto done;
+
+	if (gcam->state == GB_CAMERA_STATE_CONFIGURED) {
+		gb_camera_teardown_data_connection(gcam);
+		gcam->state = GB_CAMERA_STATE_UNCONFIGURED;
+
+		/*
+		 * When unconfiguring streams release the PM runtime reference
+		 * that was acquired when streams were configured. The bundle
+		 * won't be suspended until the PM runtime reference acquired at
+		 * the beginning of this function gets released right before
+		 * returning.
+		 */
+		gb_pm_runtime_put_noidle(gcam->bundle);
+	}
+
+	if (resp->num_streams == 0)
+		goto done;
+
+	/*
+	 * Make sure the bundle won't be suspended until streams get
+	 * unconfigured after the stream is configured successfully
+	 */
+	gb_pm_runtime_get_noresume(gcam->bundle);
+
+	/* Setup CSI-2 connection from APB-A to AP */
+	ret = gb_camera_setup_data_connection(gcam, resp, csi_params);
+	if (ret < 0) {
+		memset(req, 0, sizeof(*req));
+		gb_operation_sync(gcam->connection,
+				  GB_CAMERA_TYPE_CONFIGURE_STREAMS,
+				  req, sizeof(*req),
+				  resp, sizeof(*resp));
+		*flags = 0;
+		*num_streams = 0;
+		gb_pm_runtime_put_noidle(gcam->bundle);
+		goto done;
+	}
+
+	gcam->state = GB_CAMERA_STATE_CONFIGURED;
+
+done:
+	gb_pm_runtime_put_autosuspend(gcam->bundle);
+
+done_skip_pm_put:
+	mutex_unlock(&gcam->mutex);
+	kfree(req);
+	kfree(resp);
+	return ret;
+}
+
+static int gb_camera_capture(struct gb_camera *gcam, u32 request_id,
+			     unsigned int streams, unsigned int num_frames,
+			     size_t settings_size, const void *settings)
+{
+	struct gb_camera_capture_request *req;
+	size_t req_size;
+	int ret;
+
+	if (settings_size > GB_CAMERA_MAX_SETTINGS_SIZE)
+		return -EINVAL;
+
+	req_size = sizeof(*req) + settings_size;
+	req = kmalloc(req_size, GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+
+	req->request_id = cpu_to_le32(request_id);
+	req->streams = streams;
+	req->padding = 0;
+	req->num_frames = cpu_to_le16(num_frames);
+	memcpy(req->settings, settings, settings_size);
+
+	mutex_lock(&gcam->mutex);
+
+	if (!gcam->connection) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	ret = gb_operation_sync(gcam->connection, GB_CAMERA_TYPE_CAPTURE,
+				req, req_size, NULL, 0);
+done:
+	mutex_unlock(&gcam->mutex);
+
+	kfree(req);
+
+	return ret;
+}
+
+static int gb_camera_flush(struct gb_camera *gcam, u32 *request_id)
+{
+	struct gb_camera_flush_response resp;
+	int ret;
+
+	mutex_lock(&gcam->mutex);
+
+	if (!gcam->connection) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	ret = gb_operation_sync(gcam->connection, GB_CAMERA_TYPE_FLUSH, NULL, 0,
+				&resp, sizeof(resp));
+
+	if (ret < 0)
+		goto done;
+
+	if (request_id)
+		*request_id = le32_to_cpu(resp.request_id);
+
+done:
+	mutex_unlock(&gcam->mutex);
+
+	return ret;
+}
+
+static int gb_camera_request_handler(struct gb_operation *op)
+{
+	struct gb_camera *gcam = gb_connection_get_data(op->connection);
+	struct gb_camera_metadata_request *payload;
+	struct gb_message *request;
+
+	if (op->type != GB_CAMERA_TYPE_METADATA) {
+		gcam_err(gcam, "Unsupported unsolicited event: %u\n", op->type);
+		return -EINVAL;
+	}
+
+	request = op->request;
+
+	if (request->payload_size < sizeof(*payload)) {
+		gcam_err(gcam, "Wrong event size received (%zu < %zu)\n",
+			 request->payload_size, sizeof(*payload));
+		return -EINVAL;
+	}
+
+	payload = request->payload;
+
+	gcam_dbg(gcam, "received metadata for request %u, frame %u, stream %u\n",
+		 payload->request_id, payload->frame_number, payload->stream);
+
+	return 0;
+}
+
+/* -----------------------------------------------------------------------------
+ * Interface with HOST gmp camera.
+ */
+static unsigned int gb_camera_mbus_to_gb(enum v4l2_mbus_pixelcode mbus_code)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gb_fmt_info); i++) {
+		if (gb_fmt_info[i].mbus_code == mbus_code)
+			return gb_fmt_info[i].gb_format;
+	}
+	return gb_fmt_info[0].gb_format;
+}
+
+static enum v4l2_mbus_pixelcode gb_camera_gb_to_mbus(u16 gb_fmt)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gb_fmt_info); i++) {
+		if (gb_fmt_info[i].gb_format == gb_fmt)
+			return gb_fmt_info[i].mbus_code;
+	}
+	return gb_fmt_info[0].mbus_code;
+}
+
+static ssize_t gb_camera_op_capabilities(void *priv, char *data, size_t len)
+{
+	struct gb_camera *gcam = priv;
+	size_t capabilities_len = len;
+	int ret;
+
+	ret = gb_camera_capabilities(gcam, data, &capabilities_len);
+	if (ret)
+		return ret;
+
+	return capabilities_len;
+}
+
+static int gb_camera_op_configure_streams(void *priv, unsigned int *nstreams,
+		unsigned int *flags, struct gb_camera_stream *streams,
+		struct gb_camera_csi_params *csi_params)
+{
+	struct gb_camera *gcam = priv;
+	struct gb_camera_stream_config *gb_streams;
+	unsigned int gb_flags = 0;
+	unsigned int gb_nstreams = *nstreams;
+	unsigned int i;
+	int ret;
+
+	if (gb_nstreams > GB_CAMERA_MAX_STREAMS)
+		return -EINVAL;
+
+	gb_streams = kzalloc(gb_nstreams * sizeof(*gb_streams), GFP_KERNEL);
+	if (!gb_streams)
+		return -ENOMEM;
+
+	for (i = 0; i < gb_nstreams; i++) {
+		gb_streams[i].width = streams[i].width;
+		gb_streams[i].height = streams[i].height;
+		gb_streams[i].format =
+			gb_camera_mbus_to_gb(streams[i].pixel_code);
+	}
+
+	if (*flags & GB_CAMERA_IN_FLAG_TEST)
+		gb_flags |= GB_CAMERA_CONFIGURE_STREAMS_TEST_ONLY;
+
+	ret = gb_camera_configure_streams(gcam, &gb_nstreams,
+					  &gb_flags, gb_streams, csi_params);
+	if (ret < 0)
+		goto done;
+	if (gb_nstreams > *nstreams) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	*flags = 0;
+	if (gb_flags & GB_CAMERA_CONFIGURE_STREAMS_ADJUSTED)
+		*flags |= GB_CAMERA_OUT_FLAG_ADJUSTED;
+
+	for (i = 0; i < gb_nstreams; i++) {
+		streams[i].width = gb_streams[i].width;
+		streams[i].height = gb_streams[i].height;
+		streams[i].vc = gb_streams[i].vc;
+		streams[i].dt[0] = gb_streams[i].dt[0];
+		streams[i].dt[1] = gb_streams[i].dt[1];
+		streams[i].max_size = gb_streams[i].max_size;
+		streams[i].pixel_code =
+			gb_camera_gb_to_mbus(gb_streams[i].format);
+	}
+	*nstreams = gb_nstreams;
+
+done:
+	kfree(gb_streams);
+	return ret;
+}
+
+static int gb_camera_op_capture(void *priv, u32 request_id,
+		unsigned int streams, unsigned int num_frames,
+		size_t settings_size, const void *settings)
+{
+	struct gb_camera *gcam = priv;
+
+	return gb_camera_capture(gcam, request_id, streams, num_frames,
+				 settings_size, settings);
+}
+
+static int gb_camera_op_flush(void *priv, u32 *request_id)
+{
+	struct gb_camera *gcam = priv;
+
+	return gb_camera_flush(gcam, request_id);
+}
+
+static const struct gb_camera_ops gb_cam_ops = {
+	.capabilities = gb_camera_op_capabilities,
+	.configure_streams = gb_camera_op_configure_streams,
+	.capture = gb_camera_op_capture,
+	.flush = gb_camera_op_flush,
+};
+
+/* -----------------------------------------------------------------------------
+ * DebugFS
+ */
+
+static ssize_t gb_camera_debugfs_capabilities(struct gb_camera *gcam,
+		char *buf, size_t len)
+{
+	struct gb_camera_debugfs_buffer *buffer =
+		&gcam->debugfs.buffers[GB_CAMERA_DEBUGFS_BUFFER_CAPABILITIES];
+	size_t size = 1024;
+	unsigned int i;
+	u8 *caps;
+	int ret;
+
+	caps = kmalloc(size, GFP_KERNEL);
+	if (!caps)
+		return -ENOMEM;
+
+	ret = gb_camera_capabilities(gcam, caps, &size);
+	if (ret < 0)
+		goto done;
+
+	/*
+	 * hex_dump_to_buffer() doesn't return the number of bytes dumped prior
+	 * to v4.0, we need our own implementation :-(
+	 */
+	buffer->length = 0;
+
+	for (i = 0; i < size; i += 16) {
+		unsigned int nbytes = min_t(unsigned int, size - i, 16);
+
+		buffer->length += sprintf(buffer->data + buffer->length,
+					  "%*ph\n", nbytes, caps + i);
+	}
+
+done:
+	kfree(caps);
+	return ret;
+}
+
+static ssize_t gb_camera_debugfs_configure_streams(struct gb_camera *gcam,
+		char *buf, size_t len)
+{
+	struct gb_camera_debugfs_buffer *buffer =
+		&gcam->debugfs.buffers[GB_CAMERA_DEBUGFS_BUFFER_STREAMS];
+	struct gb_camera_stream_config *streams;
+	unsigned int nstreams;
+	unsigned int flags;
+	unsigned int i;
+	char *token;
+	int ret;
+
+	/* Retrieve number of streams to configure */
+	token = strsep(&buf, ";");
+	if (token == NULL)
+		return -EINVAL;
+
+	ret = kstrtouint(token, 10, &nstreams);
+	if (ret < 0)
+		return ret;
+
+	if (nstreams > GB_CAMERA_MAX_STREAMS)
+		return -EINVAL;
+
+	token = strsep(&buf, ";");
+	if (token == NULL)
+		return -EINVAL;
+
+	ret = kstrtouint(token, 10, &flags);
+	if (ret < 0)
+		return ret;
+
+	/* For each stream to configure parse width, height and format */
+	streams = kzalloc(nstreams * sizeof(*streams), GFP_KERNEL);
+	if (!streams)
+		return -ENOMEM;
+
+	for (i = 0; i < nstreams; ++i) {
+		struct gb_camera_stream_config *stream = &streams[i];
+
+		/* width */
+		token = strsep(&buf, ";");
+		if (token == NULL) {
+			ret = -EINVAL;
+			goto done;
+		}
+		ret = kstrtouint(token, 10, &stream->width);
+		if (ret < 0)
+			goto done;
+
+		/* height */
+		token = strsep(&buf, ";");
+		if (token == NULL)
+			goto done;
+
+		ret = kstrtouint(token, 10, &stream->height);
+		if (ret < 0)
+			goto done;
+
+		/* Image format code */
+		token = strsep(&buf, ";");
+		if (token == NULL)
+			goto done;
+
+		ret = kstrtouint(token, 16, &stream->format);
+		if (ret < 0)
+			goto done;
+	}
+
+	ret = gb_camera_configure_streams(gcam, &nstreams, &flags, streams,
+					  NULL);
+	if (ret < 0)
+		goto done;
+
+	buffer->length = sprintf(buffer->data, "%u;%u;", nstreams, flags);
+
+	for (i = 0; i < nstreams; ++i) {
+		struct gb_camera_stream_config *stream = &streams[i];
+
+		buffer->length += sprintf(buffer->data + buffer->length,
+					  "%u;%u;%u;%u;%u;%u;%u;",
+					  stream->width, stream->height,
+					  stream->format, stream->vc,
+					  stream->dt[0], stream->dt[1],
+					  stream->max_size);
+	}
+
+	ret = len;
+
+done:
+	kfree(streams);
+	return ret;
+};
+
+static ssize_t gb_camera_debugfs_capture(struct gb_camera *gcam,
+		char *buf, size_t len)
+{
+	unsigned int request_id;
+	unsigned int streams_mask;
+	unsigned int num_frames;
+	char *token;
+	int ret;
+
+	/* Request id */
+	token = strsep(&buf, ";");
+	if (token == NULL)
+		return -EINVAL;
+	ret = kstrtouint(token, 10, &request_id);
+	if (ret < 0)
+		return ret;
+
+	/* Stream mask */
+	token = strsep(&buf, ";");
+	if (token == NULL)
+		return -EINVAL;
+	ret = kstrtouint(token, 16, &streams_mask);
+	if (ret < 0)
+		return ret;
+
+	/* number of frames */
+	token = strsep(&buf, ";");
+	if (token == NULL)
+		return -EINVAL;
+	ret = kstrtouint(token, 10, &num_frames);
+	if (ret < 0)
+		return ret;
+
+	ret = gb_camera_capture(gcam, request_id, streams_mask, num_frames, 0,
+				NULL);
+	if (ret < 0)
+		return ret;
+
+	return len;
+}
+
+static ssize_t gb_camera_debugfs_flush(struct gb_camera *gcam,
+		char *buf, size_t len)
+{
+	struct gb_camera_debugfs_buffer *buffer =
+		&gcam->debugfs.buffers[GB_CAMERA_DEBUGFS_BUFFER_FLUSH];
+	unsigned int req_id;
+	int ret;
+
+	ret = gb_camera_flush(gcam, &req_id);
+	if (ret < 0)
+		return ret;
+
+	buffer->length = sprintf(buffer->data, "%u", req_id);
+
+	return len;
+}
+
+struct gb_camera_debugfs_entry {
+	const char *name;
+	unsigned int mask;
+	unsigned int buffer;
+	ssize_t (*execute)(struct gb_camera *gcam, char *buf, size_t len);
+};
+
+static const struct gb_camera_debugfs_entry gb_camera_debugfs_entries[] = {
+	{
+		.name = "capabilities",
+		.mask = S_IFREG | S_IRUGO,
+		.buffer = GB_CAMERA_DEBUGFS_BUFFER_CAPABILITIES,
+		.execute = gb_camera_debugfs_capabilities,
+	}, {
+		.name = "configure_streams",
+		.mask = S_IFREG | S_IRUGO | S_IWUGO,
+		.buffer = GB_CAMERA_DEBUGFS_BUFFER_STREAMS,
+		.execute = gb_camera_debugfs_configure_streams,
+	}, {
+		.name = "capture",
+		.mask = S_IFREG | S_IRUGO | S_IWUGO,
+		.buffer = GB_CAMERA_DEBUGFS_BUFFER_CAPTURE,
+		.execute = gb_camera_debugfs_capture,
+	}, {
+		.name = "flush",
+		.mask = S_IFREG | S_IRUGO | S_IWUGO,
+		.buffer = GB_CAMERA_DEBUGFS_BUFFER_FLUSH,
+		.execute = gb_camera_debugfs_flush,
+	},
+};
+
+static ssize_t gb_camera_debugfs_read(struct file *file, char __user *buf,
+				      size_t len, loff_t *offset)
+{
+	const struct gb_camera_debugfs_entry *op = file->private_data;
+	struct gb_camera *gcam = file->f_inode->i_private;
+	struct gb_camera_debugfs_buffer *buffer;
+	ssize_t ret;
+
+	/* For read-only entries the operation is triggered by a read. */
+	if (!(op->mask & S_IWUGO)) {
+		ret = op->execute(gcam, NULL, 0);
+		if (ret < 0)
+			return ret;
+	}
+
+	buffer = &gcam->debugfs.buffers[op->buffer];
+
+	return simple_read_from_buffer(buf, len, offset, buffer->data,
+				       buffer->length);
+}
+
+static ssize_t gb_camera_debugfs_write(struct file *file,
+				       const char __user *buf, size_t len,
+				       loff_t *offset)
+{
+	const struct gb_camera_debugfs_entry *op = file->private_data;
+	struct gb_camera *gcam = file->f_inode->i_private;
+	ssize_t ret;
+	char *kbuf;
+
+	if (len > 1024)
+	       return -EINVAL;
+
+	kbuf = kmalloc(len + 1, GFP_KERNEL);
+	if (kbuf == NULL)
+		return -ENOMEM;
+
+	if (copy_from_user(kbuf, buf, len)) {
+		ret = -EFAULT;
+		goto done;
+	}
+
+	kbuf[len] = '\0';
+
+	ret = op->execute(gcam, kbuf, len);
+
+done:
+	kfree(kbuf);
+	return ret;
+}
+
+static int gb_camera_debugfs_open(struct inode *inode, struct file *file)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gb_camera_debugfs_entries); ++i) {
+		const struct gb_camera_debugfs_entry *entry =
+			&gb_camera_debugfs_entries[i];
+
+		if (!strcmp(file->f_path.dentry->d_iname, entry->name)) {
+			file->private_data = (void *)entry;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static const struct file_operations gb_camera_debugfs_ops = {
+	.open = gb_camera_debugfs_open,
+	.read = gb_camera_debugfs_read,
+	.write = gb_camera_debugfs_write,
+};
+
+static int gb_camera_debugfs_init(struct gb_camera *gcam)
+{
+	struct gb_connection *connection = gcam->connection;
+	char dirname[27];
+	unsigned int i;
+
+	/*
+	 * Create root debugfs entry and a file entry for each camera operation.
+	 */
+	snprintf(dirname, 27, "camera-%u.%u", connection->intf->interface_id,
+		 gcam->bundle->id);
+
+	gcam->debugfs.root = debugfs_create_dir(dirname, gb_debugfs_get());
+	if (IS_ERR(gcam->debugfs.root)) {
+		gcam_err(gcam, "debugfs root create failed (%ld)\n",
+			 PTR_ERR(gcam->debugfs.root));
+		return PTR_ERR(gcam->debugfs.root);
+	}
+
+	gcam->debugfs.buffers = vmalloc(sizeof(*gcam->debugfs.buffers) *
+					GB_CAMERA_DEBUGFS_BUFFER_MAX);
+	if (!gcam->debugfs.buffers)
+		return -ENOMEM;
+
+	for (i = 0; i < ARRAY_SIZE(gb_camera_debugfs_entries); ++i) {
+		const struct gb_camera_debugfs_entry *entry =
+			&gb_camera_debugfs_entries[i];
+		struct dentry *dentry;
+
+		gcam->debugfs.buffers[i].length = 0;
+
+		dentry = debugfs_create_file(entry->name, entry->mask,
+					     gcam->debugfs.root, gcam,
+					     &gb_camera_debugfs_ops);
+		if (IS_ERR(dentry)) {
+			gcam_err(gcam,
+				 "debugfs operation %s create failed (%ld)\n",
+				 entry->name, PTR_ERR(dentry));
+			return PTR_ERR(dentry);
+		}
+	}
+
+	return 0;
+}
+
+static void gb_camera_debugfs_cleanup(struct gb_camera *gcam)
+{
+	debugfs_remove_recursive(gcam->debugfs.root);
+
+	vfree(gcam->debugfs.buffers);
+}
+
+/* -----------------------------------------------------------------------------
+ * Init & Cleanup
+ */
+
+static void gb_camera_cleanup(struct gb_camera *gcam)
+{
+	gb_camera_debugfs_cleanup(gcam);
+
+	mutex_lock(&gcam->mutex);
+	if (gcam->data_connection) {
+		gb_connection_disable(gcam->data_connection);
+		gb_connection_destroy(gcam->data_connection);
+		gcam->data_connection = NULL;
+	}
+
+	if (gcam->connection) {
+		gb_connection_disable(gcam->connection);
+		gb_connection_destroy(gcam->connection);
+		gcam->connection = NULL;
+	}
+	mutex_unlock(&gcam->mutex);
+}
+
+static void gb_camera_release_module(struct kref *ref)
+{
+	struct gb_camera_module *cam_mod =
+		container_of(ref, struct gb_camera_module, refcount);
+	kfree(cam_mod->priv);
+}
+
+static int gb_camera_probe(struct gb_bundle *bundle,
+			   const struct greybus_bundle_id *id)
+{
+	struct gb_connection *conn;
+	struct gb_camera *gcam;
+	u16 mgmt_cport_id = 0;
+	u16 data_cport_id = 0;
+	unsigned int i;
+	int ret;
+
+	/*
+	 * The camera bundle must contain exactly two CPorts, one for the
+	 * camera management protocol and one for the camera data protocol.
+	 */
+	if (bundle->num_cports != 2)
+		return -ENODEV;
+
+	for (i = 0; i < bundle->num_cports; ++i) {
+		struct greybus_descriptor_cport *desc = &bundle->cport_desc[i];
+
+		switch (desc->protocol_id) {
+		case GREYBUS_PROTOCOL_CAMERA_MGMT:
+			mgmt_cport_id = le16_to_cpu(desc->id);
+			break;
+		case GREYBUS_PROTOCOL_CAMERA_DATA:
+			data_cport_id = le16_to_cpu(desc->id);
+			break;
+		default:
+			return -ENODEV;
+		}
+	}
+
+	if (!mgmt_cport_id || !data_cport_id)
+		return -ENODEV;
+
+	gcam = kzalloc(sizeof(*gcam), GFP_KERNEL);
+	if (!gcam)
+		return -ENOMEM;
+
+	mutex_init(&gcam->mutex);
+
+	gcam->bundle = bundle;
+	gcam->state = GB_CAMERA_STATE_UNCONFIGURED;
+	gcam->data_cport_id = data_cport_id;
+
+	conn = gb_connection_create(bundle, mgmt_cport_id,
+				    gb_camera_request_handler);
+	if (IS_ERR(conn)) {
+		ret = PTR_ERR(conn);
+		goto error;
+	}
+
+	gcam->connection = conn;
+	gb_connection_set_data(conn, gcam);
+
+	ret = gb_connection_enable(conn);
+	if (ret)
+		goto error;
+
+	ret = gb_camera_debugfs_init(gcam);
+	if (ret < 0)
+		goto error;
+
+	gcam->module.priv = gcam;
+	gcam->module.ops = &gb_cam_ops;
+	gcam->module.interface_id = gcam->connection->intf->interface_id;
+	gcam->module.release = gb_camera_release_module;
+	ret = gb_camera_register(&gcam->module);
+	if (ret < 0)
+		goto error;
+
+	greybus_set_drvdata(bundle, gcam);
+
+	gb_pm_runtime_put_autosuspend(gcam->bundle);
+
+	return 0;
+
+error:
+	gb_camera_cleanup(gcam);
+	kfree(gcam);
+	return ret;
+}
+
+static void gb_camera_disconnect(struct gb_bundle *bundle)
+{
+	struct gb_camera *gcam = greybus_get_drvdata(bundle);
+	int ret;
+
+	ret = gb_pm_runtime_get_sync(bundle);
+	if (ret)
+		gb_pm_runtime_get_noresume(bundle);
+
+	gb_camera_cleanup(gcam);
+	gb_camera_unregister(&gcam->module);
+}
+
+static const struct greybus_bundle_id gb_camera_id_table[] = {
+	{ GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_CAMERA) },
+	{ },
+};
+
+#ifdef CONFIG_PM
+static int gb_camera_suspend(struct device *dev)
+{
+	struct gb_bundle *bundle = to_gb_bundle(dev);
+	struct gb_camera *gcam = greybus_get_drvdata(bundle);
+
+	if (gcam->data_connection)
+		gb_connection_disable(gcam->data_connection);
+
+	gb_connection_disable(gcam->connection);
+
+	return 0;
+}
+
+static int gb_camera_resume(struct device *dev)
+{
+	struct gb_bundle *bundle = to_gb_bundle(dev);
+	struct gb_camera *gcam = greybus_get_drvdata(bundle);
+	int ret;
+
+	ret = gb_connection_enable(gcam->connection);
+	if (ret) {
+		gcam_err(gcam, "failed to enable connection: %d\n", ret);
+		return ret;
+	}
+
+	if (gcam->data_connection) {
+		ret = gb_connection_enable(gcam->data_connection);
+		if (ret) {
+			gcam_err(gcam,
+				 "failed to enable data connection: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops gb_camera_pm_ops = {
+	SET_RUNTIME_PM_OPS(gb_camera_suspend, gb_camera_resume, NULL)
+};
+
+static struct greybus_driver gb_camera_driver = {
+	.name		= "camera",
+	.probe		= gb_camera_probe,
+	.disconnect	= gb_camera_disconnect,
+	.id_table	= gb_camera_id_table,
+	.driver.pm	= &gb_camera_pm_ops,
+};
+
+module_greybus_driver(gb_camera_driver);
+
+MODULE_LICENSE("GPL v2");
--- /dev/null
+++ b/drivers/greybus/gb-camera.h
@@ -0,0 +1,127 @@
+/*
+ * Greybus Camera protocol driver.
+ *
+ * Copyright 2015 Google Inc.
+ *
+ * Released under the GPLv2 only.
+ */
+#ifndef __GB_CAMERA_H
+#define __GB_CAMERA_H
+
+#include <linux/v4l2-mediabus.h>
+
+/* Input flags need to be set from the caller */
+#define GB_CAMERA_IN_FLAG_TEST		(1 << 0)
+/* Output flags returned */
+#define GB_CAMERA_OUT_FLAG_ADJUSTED	(1 << 0)
+
+/**
+ * struct gb_camera_stream - Represents greybus camera stream.
+ * @width: Stream width in pixels.
+ * @height: Stream height in pixels.
+ * @pixel_code: Media bus pixel code.
+ * @vc: MIPI CSI virtual channel.
+ * @dt: MIPI CSI data types. Most formats use a single data type, in which case
+ *      the second element will be ignored.
+ * @max_size: Maximum size of a frame in bytes. The camera module guarantees
+ *            that all data between the Frame Start and Frame End packet for
+ *            the associated virtual channel and data type(s) will not exceed
+ *            this size.
+ */
+struct gb_camera_stream {
+	unsigned int width;
+	unsigned int height;
+	enum v4l2_mbus_pixelcode pixel_code;
+	unsigned int vc;
+	unsigned int dt[2];
+	unsigned int max_size;
+};
+
+/**
+ * struct gb_camera_csi_params - CSI configuration parameters
+ * @num_lanes: number of CSI data lanes
+ * @clk_freq: CSI clock frequency in Hz
+ */
+struct gb_camera_csi_params {
+	unsigned int num_lanes;
+	unsigned int clk_freq;
+};
+
+/**
+ * struct gb_camera_ops - Greybus camera operations, used by the Greybus camera
+ *                        driver to expose operations to the host camera driver.
+ * @capabilities: Retrieve camera capabilities and store them in the buffer
+ *                'buf' capabilities. The buffer maximum size is specified by
+ *                the caller in the 'size' parameter, and the effective
+ *                capabilities size is returned from the function. If the buffer
+ *                size is too small to hold the capabilities an error is
+ *                returned and the buffer is left untouched.
+ *
+ * @configure_streams: Negotiate configuration and prepare the module for video
+ *                     capture. The caller specifies the number of streams it
+ *                     requests in the 'nstreams' argument and the associated
+ *                     streams configurations in the 'streams' argument. The
+ *                     GB_CAMERA_IN_FLAG_TEST 'flag' can be set to test a
+ *                     configuration without applying it, otherwise the
+ *                     configuration is applied by the module. The module can
+ *                     decide to modify the requested configuration, including
+ *                     using a different number of streams. In that case the
+ *                     modified configuration won't be applied, the
+ *                     GB_CAMERA_OUT_FLAG_ADJUSTED 'flag' will be set upon
+ *                     return, and the modified configuration and number of
+ *                     streams stored in 'streams' and 'array'. The module
+ *                     returns its CSI-2 bus parameters in the 'csi_params'
+ *                     structure in all cases.
+ *
+ * @capture: Submit a capture request. The supplied 'request_id' must be unique
+ *           and higher than the IDs of all the previously submitted requests.
+ *           The 'streams' argument specifies which streams are affected by the
+ *           request in the form of a bitmask, with bits corresponding to the
+ *           configured streams indexes. If the request contains settings, the
+ *           'settings' argument points to the settings buffer and its size is
+ *           specified by the 'settings_size' argument. Otherwise the 'settings'
+ *           argument should be set to NULL and 'settings_size' to 0.
+ *
+ * @flush: Flush the capture requests queue. Return the ID of the last request
+ *         that will processed by the device before it stops transmitting video
+ *         frames. All queued capture requests with IDs higher than the returned
+ *         ID will be dropped without being processed.
+ */
+struct gb_camera_ops {
+	ssize_t (*capabilities)(void *priv, char *buf, size_t len);
+	int (*configure_streams)(void *priv, unsigned int *nstreams,
+			unsigned int *flags, struct gb_camera_stream *streams,
+			struct gb_camera_csi_params *csi_params);
+	int (*capture)(void *priv, u32 request_id,
+			unsigned int streams, unsigned int num_frames,
+			size_t settings_size, const void *settings);
+	int (*flush)(void *priv, u32 *request_id);
+};
+
+/**
+ * struct gb_camera_module - Represents greybus camera module.
+ * @priv: Module private data, passed to all camera operations.
+ * @ops: Greybus camera operation callbacks.
+ * @interface_id: Interface id of the module.
+ * @refcount: Reference counting object.
+ * @release: Module release function.
+ * @list: List entry in the camera modules list.
+ */
+struct gb_camera_module {
+	void *priv;
+	const struct gb_camera_ops *ops;
+
+	unsigned int interface_id;
+	struct kref refcount;
+	void (*release)(struct kref *kref);
+	struct list_head list; /* Global list */
+};
+
+#define gb_camera_call(f, op, args...)      \
+	(!(f) ? -ENODEV : (((f)->ops->op) ?  \
+	(f)->ops->op((f)->priv, ##args) : -ENOIOCTLCMD))
+
+int gb_camera_register(struct gb_camera_module *module);
+int gb_camera_unregister(struct gb_camera_module *module);
+
+#endif /* __GB_CAMERA_H */