greybus: allocate space without gbufs

This begins the transition to buffer allocation that does not rely
on the gbuf construct.

The host driver allocation routine will return a pointer to the
buffer to be used, and the caller will be responsible for keeping
track of that pointer, as well as the requested buffer size.

Rename the allocation method to reflect it's no longer tied to a
gbuf.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/core.c

@@ -169,7 +169,7 @@ struct greybus_host_device *greybus_create_hd(struct greybus_host_driver *driver
 	 * Validate that the driver implements all of the callbacks
 	 * so that we don't have to every time we make them.
 	 */
-	if ((!driver->alloc_gbuf_data) ||
+	if ((!driver->buffer_alloc) ||
 	    (!driver->free_gbuf_data) ||
 	    (!driver->submit_svc) ||
 	    (!driver->submit_gbuf) ||

drivers/staging/greybus/es1-ap-usb.c

@@ -85,21 +85,12 @@ static inline struct es1_ap_dev *hd_to_es1(struct greybus_host_device *hd)
 static void cport_out_callback(struct urb *urb);
 
 /*
- * Allocate the actual buffer for this gbuf and device and cport
- *
- * We are responsible for setting the following fields in a struct gbuf:
- *	void *hcpriv;
- *	void *transfer_buffer;
- *	u32 transfer_buffer_length;
+ * Allocate a buffer to be sent via UniPro.
  */
-static int alloc_gbuf_data(struct gbuf *gbuf, unsigned int size,
-				gfp_t gfp_mask)
+static void *buffer_alloc(unsigned int size, gfp_t gfp_mask)
 {
 	u8 *buffer;
 
-	if (gbuf->transfer_buffer)
-		return -EALREADY;
-
 	if (size > ES1_GBUF_MSG_SIZE) {
 		pr_err("guf was asked to be bigger than %ld!\n",
 		       ES1_GBUF_MSG_SIZE);
@@ -117,14 +108,10 @@ static int alloc_gbuf_data(struct gbuf *gbuf, unsigned int size,
 	 * XXX Do we need to indicate the destination device id too?
 	 */
 	buffer = kzalloc(GB_BUFFER_ALIGN + size, gfp_mask);
-	if (!buffer)
-		return -ENOMEM;
-	buffer += GB_BUFFER_ALIGN;
+	if (buffer)
+		buffer += GB_BUFFER_ALIGN;
 
-	gbuf->transfer_buffer = buffer;
-	gbuf->transfer_buffer_length = size;
-
-	return 0;
+	return buffer;
 }
 
 /* Free the memory we allocated with a gbuf */
@@ -252,7 +239,7 @@ static void kill_gbuf(struct gbuf *gbuf)
 
 static struct greybus_host_driver es1_driver = {
 	.hd_priv_size		= sizeof(struct es1_ap_dev),
-	.alloc_gbuf_data	= alloc_gbuf_data,
+	.buffer_alloc		= buffer_alloc,
 	.free_gbuf_data		= free_gbuf_data,
 	.submit_svc		= submit_svc,
 	.submit_gbuf		= submit_gbuf,

drivers/staging/greybus/greybus.h

@@ -79,8 +79,7 @@ struct gbuf;
 struct greybus_host_driver {
 	size_t	hd_priv_size;
 
-	int (*alloc_gbuf_data)(struct gbuf *gbuf, unsigned int size,
-					gfp_t gfp_mask);
+	void *(*buffer_alloc)(unsigned int size, gfp_t gfp_mask);
 	void (*free_gbuf_data)(struct gbuf *gbuf);
 	int (*submit_svc)(struct svc_msg *svc_msg,
 			    struct greybus_host_device *hd);

drivers/staging/greybus/operation.c

@@ -222,7 +222,6 @@ static int gb_operation_message_init(struct gb_operation *operation,
 	struct gbuf *gbuf;
 	gfp_t gfp_flags = request && !outbound ? GFP_ATOMIC : GFP_KERNEL;
 	u16 dest_cport_id;
-	int ret;
 
 	if (size > GB_OPERATION_MESSAGE_SIZE_MAX)
 		return -E2BIG;
@@ -241,9 +240,10 @@ static int gb_operation_message_init(struct gb_operation *operation,
 	else
 		dest_cport_id = CPORT_ID_BAD;
 
-	ret = hd->driver->alloc_gbuf_data(gbuf, size, gfp_flags);
-	if (ret)
-		return ret;
+	gbuf->transfer_buffer = hd->driver->buffer_alloc(size, gfp_flags);
+	if (!gbuf->transfer_buffer)
+		return -ENOMEM;
+	gbuf->transfer_buffer_length = size;
 	gbuf->hd = hd;
 	gbuf->dest_cport_id = dest_cport_id;
 	gbuf->status = -EBADR;	/* Initial value--means "never set" */