[kernel][ports] Add basic ports functionality

include/kernel/port.h

+/*
+ * Copyright (c) 2015 Carlos Pizano-Uribe  cpu@chromium.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#ifndef __KERNEL_PORT_H
+#define __KERNEL_PORT_H
+
+#include <sys/types.h>
+#include <compiler.h>
+
+
+__BEGIN_CDECLS;
+
+/* Ports are named, opaque objects and come in tree flavors, the
+ * write-side, the read-side and a port group which is a collection
+ * of read-side ports.
+ */
+
+#define PORT_NAME_LEN 12
+
+typedef void* port_t;
+
+typedef struct {
+    char value[8];
+} port_packet_t;
+
+typedef struct {
+    void* ctx;
+    port_packet_t packet;
+} port_result_t;
+
+typedef enum {
+    PORT_MODE_BROADCAST   = 0,
+    PORT_MODE_UNICAST     = 1,
+    PORT_MODE_BIG_BUFFER  = 2,
+} port_mode_t;
+
+/* Inits the port subsystem
+ */
+void port_init(void);
+
+/* Make a named write-side port. broadcast ports can be opened by any
+ * number of read-clients. |name| can be up to PORT_NAME_LEN chars.
+ */
+status_t port_create(const char* name, port_mode_t mode, port_t* port);
+
+/* Make a read-side port. Only non-destroyed existing write ports can
+ * be opened with this api. Unicast ports can only be opened once.
+ */
+status_t port_open(const char* name, void* ctx, port_t* port);
+
+/* Creates a read-side port group which behaves just like a regular
+ * read-side port. A given port can only be assoicated with one port group.
+ */
+status_t port_group(port_t* ports, size_t count, port_t* group);
+
+/* Write to a port |count| packets, non-blocking, all or none atomic success.
+ */
+status_t port_write(port_t port, const port_packet_t* pk, size_t count);
+
+/* Read one packet from the port or port group, blocking. The |result| contains
+ * the port that the message was read from.
+ */
+status_t port_read(port_t port, lk_time_t timeout, port_result_t* result);
+
+/* Destroy the write-side port, flush queued packets and release all resources,
+ * all calls will now fail on that port.
+ */
+status_t port_destroy(port_t port);
+
+/* Close the read-side port or the write side port. A closed write side port
+ * can be opened and the pending packets read. closing a port group does not
+ * close the included ports.
+ */
+status_t port_close(port_t port);
+
+__END_CDECLS;
+
+#endif
+