greybus: add framework for 'struct gbuf'

This is the equlivant of sk_buf or urbs for Greybus.

drivers/staging/greybus/Makefile

-greybus-y := core.o
+greybus-y := core.o gbuf.o
 
 obj-m += greybus.o
 obj-m += i2c-gb.o

drivers/staging/greybus/gbuf.c

+/*
+ * Greybus gbuf handling
+ *
+ * Copyright 2014 Google Inc.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+
+#include "greybus.h"
+
+
+struct gbuf *greybus_alloc_gbuf(struct greybus_device *gdev,
+				struct cport *cport,
+				gfp_t mem_flags)
+{
+	return NULL;
+}
+
+void greybus_free_gbuf(struct gbuf *gbuf)
+{
+}
+
+int greybus_submit_gbuf(struct gbuf *gbuf, gfp_t mem_flags)
+{
+	return -ENOMEM;
+}
+
+int greybus_kill_gbuf(struct gbuf *gbuf)
+{
+	return -ENOMEM;
+}
+
+
+

drivers/staging/greybus/greybus.h

@@ -29,19 +29,68 @@
 	.match_flags	= GREYBUS_DEVICE_ID_MATCH_SERIAL,	\
 	.lSerial	= (serial),
 
-
 struct greybus_descriptor {
 	__u16	wVendor;
 	__u16	wProduct;
 	__u64	lSerialNumber;
 };
 
+
+struct gbuf;
+
+struct cport {
+	u16	number;
+	// FIXME, what else?
+};
+
+typedef void (*gbuf_complete_t)(struct gbuf *gbuf);
+
+struct gbuf {
+	struct kref kref;
+	void *hcpriv;
+
+	struct list_head anchor_list;
+	struct gbuf_anchor *anchor;	// FIXME do we need?
+
+	struct greybus_device *gdev;
+	struct cport *cport;
+	int status;
+	void *transfer_buffer;
+	u32 transfer_flags;		/* flags for the transfer buffer */
+	u32 transfer_buffer_length;
+	u32 actual_length;
+
+	struct scatterlist *sg;		// FIXME do we need?
+	int num_sgs;
+
+	void *context;
+	gbuf_complete_t complete;
+};
+
+/*
+ * gbuf->transfer_flags
+ */
+#define GBUF_FREE_BUFFER	BIT(0)	/* Free the transfer buffer with the gbuf */
+
+
 struct greybus_device {
 	struct device dev;
 	struct greybus_descriptor descriptor;
+	int num_cport;
+	struct cport cport[0];
 };
 #define to_greybus_device(d) container_of(d, struct greybus_device, dev)
 
+
+struct gbuf *greybus_alloc_gbuf(struct greybus_device *gdev,
+				struct cport *cport,
+				gfp_t mem_flags);
+void greybus_free_gbuf(struct gbuf *gbuf);
+
+int greybus_submit_gbuf(struct gbuf *gbuf, gfp_t mem_flags);
+int greybus_kill_gbuf(struct gbuf *gbuf);
+
+
 struct greybus_driver {
 	const char *name;