usb: gadget: FunctionFS: share VLA macros with all usb gadget files

Variable Length Array macros allow portable (compilable with both gcc
and clang) way of allocating a number of structures using a single
memory chunk. They can be useful for files other than f_fs.c,
so move them to a header file.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/usb/gadget/u_f.h b/drivers/usb/gadget/u_f.h
index 71034c061fca..1d5f0eb68552 100644
--- a/drivers/usb/gadget/u_f.h
+++ b/drivers/usb/gadget/u_f.h
@@ -16,6 +16,32 @@
 #ifndef __U_F_H__
 #define __U_F_H__
 
+/* Variable Length Array Macros **********************************************/
+#define vla_group(groupname) size_t groupname##__next = 0
+#define vla_group_size(groupname) groupname##__next
+
+#define vla_item(groupname, type, name, n) \
+	size_t groupname##_##name##__offset = ({			       \
+		size_t align_mask = __alignof__(type) - 1;		       \
+		size_t offset = (groupname##__next + align_mask) & ~align_mask;\
+		size_t size = (n) * sizeof(type);			       \
+		groupname##__next = offset + size;			       \
+		offset;							       \
+	})
+
+#define vla_item_with_sz(groupname, type, name, n) \
+	size_t groupname##_##name##__sz = (n) * sizeof(type);		       \
+	size_t groupname##_##name##__offset = ({			       \
+		size_t align_mask = __alignof__(type) - 1;		       \
+		size_t offset = (groupname##__next + align_mask) & ~align_mask;\
+		size_t size = groupname##_##name##__sz;			       \
+		groupname##__next = offset + size;			       \
+		offset;							       \
+	})
+
+#define vla_ptr(ptr, groupname, name) \
+	((void *) ((char *)ptr + groupname##_##name##__offset))
+
 struct usb_ep;
 struct usb_request;