mei: support for dynamic clients

HBM version 2.0 and above allows ME clients in the system to
register/unregister after the system is fully initialized.
Clients may be added or removed after enum_resp message was
received

1. To preserve backward compatibility the driver can opt-in to receive
client add messages by setting allow_add field in enum_req

2. A new client is added upon reception of MEI_HBM_ADD_CLIENT_REQ_CMD

3. A client is removed in a lazy manner when connection request
respond with MEI_HBMS_CLIENT_NOT_FOUND status
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/debugfs.c

@@ -154,6 +154,8 @@ static ssize_t mei_dbgfs_read_devstate(struct file *fp, char __user *ubuf,
 		pos += scnprintf(buf + pos, bufsz - pos, "hbm features:\n");
 		pos += scnprintf(buf + pos, bufsz - pos, "\tPG: %01d\n",
 				 dev->hbm_f_pg_supported);
+		pos += scnprintf(buf + pos, bufsz - pos, "\tDC: %01d\n",
+				 dev->hbm_f_dc_supported);
 	}
 
 	pos += scnprintf(buf + pos, bufsz - pos, "pg:  %s, %s\n",

drivers/misc/mei/hbm.c

@@ -299,6 +299,7 @@ static int mei_hbm_enum_clients_req(struct mei_device *dev)
 	enum_req = (struct hbm_host_enum_request *)dev->wr_msg.data;
 	memset(enum_req, 0, len);
 	enum_req->hbm_cmd = HOST_ENUM_REQ_CMD;
+	enum_req->allow_add = dev->hbm_f_dc_supported;
 
 	ret = mei_write_message(dev, mei_hdr, dev->wr_msg.data);
 	if (ret) {
@@ -343,6 +344,64 @@ static int mei_hbm_me_cl_add(struct mei_device *dev,
 	return 0;
 }
 
+/**
+ * mei_hbm_add_cl_resp - send response to fw on client add request
+ *
+ * @dev: the device structure
+ * @addr: me address
+ * @status: response status
+ *
+ * Return: 0 on success and < 0 on failure
+ */
+static int mei_hbm_add_cl_resp(struct mei_device *dev, u8 addr, u8 status)
+{
+	struct mei_msg_hdr *mei_hdr = &dev->wr_msg.hdr;
+	struct hbm_add_client_response *resp;
+	const size_t len = sizeof(struct hbm_add_client_response);
+	int ret;
+
+	dev_dbg(dev->dev, "adding client response\n");
+
+	resp = (struct hbm_add_client_response *)dev->wr_msg.data;
+
+	mei_hbm_hdr(mei_hdr, len);
+	memset(resp, 0, sizeof(struct hbm_add_client_response));
+
+	resp->hbm_cmd = MEI_HBM_ADD_CLIENT_RES_CMD;
+	resp->me_addr = addr;
+	resp->status  = status;
+
+	ret = mei_write_message(dev, mei_hdr, dev->wr_msg.data);
+	if (ret)
+		dev_err(dev->dev, "add client response write failed: ret = %d\n",
+			ret);
+	return ret;
+}
+
+/**
+ * mei_hbm_fw_add_cl_req - request from the fw to add a client
+ *
+ * @dev: the device structure
+ * @req: add client request
+ *
+ * Return: 0 on success and < 0 on failure
+ */
+static int mei_hbm_fw_add_cl_req(struct mei_device *dev,
+			      struct hbm_add_client_request *req)
+{
+	int ret;
+	u8 status = MEI_HBMS_SUCCESS;
+
+	BUILD_BUG_ON(sizeof(struct hbm_add_client_request) !=
+			sizeof(struct hbm_props_response));
+
+	ret = mei_hbm_me_cl_add(dev, (struct hbm_props_response *)req);
+	if (ret)
+		status = !MEI_HBMS_SUCCESS;
+
+	return mei_hbm_add_cl_resp(dev, req->me_addr, status);
+}
+
 /**
  * mei_hbm_prop_req - request property for a single client
  *
@@ -610,8 +669,11 @@ static void mei_hbm_cl_connect_res(struct mei_device *dev, struct mei_cl *cl,
 
 	if (rs->status == MEI_CL_CONN_SUCCESS)
 		cl->state = MEI_FILE_CONNECTED;
-	else
+	else {
 		cl->state = MEI_FILE_DISCONNECT_REPLY;
+		if (rs->status == MEI_CL_CONN_NOT_FOUND)
+			mei_me_cl_del(dev, cl->me_cl);
+	}
 	cl->status = mei_cl_conn_status_to_errno(rs->status);
 }
 
@@ -709,6 +771,9 @@ static void mei_hbm_config_features(struct mei_device *dev)
 	if (dev->version.major_version == HBM_MAJOR_VERSION_PGI &&
 	    dev->version.minor_version >= HBM_MINOR_VERSION_PGI)
 		dev->hbm_f_pg_supported = 1;
+
+	if (dev->version.major_version >= HBM_MAJOR_VERSION_DC)
+		dev->hbm_f_dc_supported = 1;
 }
 
 /**
@@ -740,6 +805,8 @@ int mei_hbm_dispatch(struct mei_device *dev, struct mei_msg_hdr *hdr)
 	struct hbm_host_version_response *version_res;
 	struct hbm_props_response *props_res;
 	struct hbm_host_enum_response *enum_res;
+	struct hbm_add_client_request *add_cl_req;
+	int ret;
 
 	struct mei_hbm_cl_cmd *cl_cmd;
 	struct hbm_client_connect_request *disconnect_req;
@@ -937,6 +1004,29 @@ int mei_hbm_dispatch(struct mei_device *dev, struct mei_msg_hdr *hdr)
 			return -EIO;
 		}
 		break;
+
+	case MEI_HBM_ADD_CLIENT_REQ_CMD:
+		dev_dbg(dev->dev, "hbm: add client request received\n");
+		/*
+		 * after the host receives the enum_resp
+		 * message clients may be added or removed
+		 */
+		if (dev->hbm_state <= MEI_HBM_ENUM_CLIENTS &&
+		    dev->hbm_state >= MEI_HBM_STOPPED) {
+			dev_err(dev->dev, "hbm: add client: state mismatch, [%d, %d]\n",
+				dev->dev_state, dev->hbm_state);
+			return -EPROTO;
+		}
+		add_cl_req = (struct hbm_add_client_request *)mei_msg;
+		ret = mei_hbm_fw_add_cl_req(dev, add_cl_req);
+		if (ret) {
+			dev_err(dev->dev, "hbm: add client: failed to send response %d\n",
+				ret);
+			return -EIO;
+		}
+		dev_dbg(dev->dev, "hbm: add client request processed\n");
+		break;
+
 	default:
 		BUG();
 		break;

drivers/misc/mei/hw.h

@@ -46,6 +46,12 @@
 #define HBM_MINOR_VERSION_PGI               1
 #define HBM_MAJOR_VERSION_PGI               1
 
+/*
+ * MEI version with Dynamic clients support
+ */
+#define HBM_MINOR_VERSION_DC               0
+#define HBM_MAJOR_VERSION_DC               2
+
 /* Host bus message command opcode */
 #define MEI_HBM_CMD_OP_MSK                  0x7f
 /* Host bus message command RESPONSE */
@@ -81,6 +87,8 @@
 #define MEI_PG_ISOLATION_EXIT_REQ_CMD       0x0b
 #define MEI_PG_ISOLATION_EXIT_RES_CMD       0x8b
 
+#define MEI_HBM_ADD_CLIENT_REQ_CMD          0x0f
+#define MEI_HBM_ADD_CLIENT_RES_CMD          0x8f
 /*
  * MEI Stop Reason
  * used by hbm_host_stop_request.reason
@@ -213,9 +221,17 @@ struct hbm_me_stop_request {
 	u8 reserved[2];
 } __packed;
 
+/**
+ * struct hbm_host_enum_request -  enumeration request from host to fw
+ *
+ * @hbm_cmd: bus message command header
+ * @allow_add: allow dynamic clients add HBM version >= 2.0
+ * @reserved: reserved
+ */
 struct hbm_host_enum_request {
 	u8 hbm_cmd;
-	u8 reserved[3];
+	u8 allow_add;
+	u8 reserved[2];
 } __packed;
 
 struct hbm_host_enum_response {
@@ -247,6 +263,38 @@ struct hbm_props_response {
 	struct mei_client_properties client_properties;
 } __packed;
 
+/**
+ * struct hbm_add_client_request - request to add a client
+ *     might be sent by fw after enumeration has already completed
+ *
+ * @hbm_cmd: bus message command header
+ * @me_addr: address of the client in ME
+ * @reserved: reserved
+ * @client_properties: client properties
+ */
+struct hbm_add_client_request {
+	u8 hbm_cmd;
+	u8 me_addr;
+	u8 reserved[2];
+	struct mei_client_properties client_properties;
+} __packed;
+
+/**
+ * struct hbm_add_client_response - response to add a client
+ *     sent by the host to report client addition status to fw
+ *
+ * @hbm_cmd: bus message command header
+ * @me_addr: address of the client in ME
+ * @status: if HBMS_SUCCESS then the client can now accept connections.
+ * @reserved: reserved
+ */
+struct hbm_add_client_response {
+	u8 hbm_cmd;
+	u8 me_addr;
+	u8 status;
+	u8 reserved[1];
+} __packed;
+
 /**
  * struct hbm_power_gate - power gate request/response
  *

drivers/misc/mei/mei_dev.h

@@ -408,6 +408,7 @@ const char *mei_pg_state_str(enum mei_pg_state state);
  *
  * @version     : HBM protocol version in use
  * @hbm_f_pg_supported : hbm feature pgi protocol
+ * @hbm_f_dc_supported : hbm feature dynamic clients
  *
  * @me_clients_rwsem: rw lock over me_clients list
  * @me_clients  : list of FW clients
@@ -501,6 +502,7 @@ struct mei_device {
 
 	struct hbm_version version;
 	unsigned int hbm_f_pg_supported:1;
+	unsigned int hbm_f_dc_supported:1;
 
 	struct rw_semaphore me_clients_rwsem;
 	struct list_head me_clients;