diff options
Diffstat (limited to 'include/usb.h')
| -rw-r--r-- | include/usb.h | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/include/usb.h b/include/usb.h index 0c96b19db1..43eb409c1a 100644 --- a/include/usb.h +++ b/include/usb.h @@ -254,15 +254,21 @@ extern struct stm32_endpoint btable_ep[]; /* Read from USB RAM into a usb_setup_packet struct */ void usb_read_setup_packet(usb_uint *buffer, struct usb_setup_packet *packet); -/* Copy data to the USB dedicated RAM and take care of the weird addressing */ -static inline void memcpy_usbram(usb_uint *ebuf, const uint8_t *src, int size) -{ - int i; - for (i = 0; i < size / 2; i++, src += 2) - *ebuf++ = src[0] | (src[1] << 8); - if (size & 1) - *ebuf++ = src[0]; -} +/* + * Copy data to and from the USB dedicated RAM and take care of the weird + * addressing. These functions correctly handle unaligned accesses to the USB + * memory. They have the same prototype as memcpy, allowing them to be used + * in places that expect memcpy. + * + * The USB packet RAM is attached to the processor via the AHB2APB bridge. This + * bridge performs manipulations of read and write accesses as per the note in + * section 2.1 of RM0091. The upshot is that it is OK to read from the packet + * RAM using 8-bit or 16-bit accesses, but not 32-bit, and it is only really OK + * to write to the packet RAM using 16-bit accesses. Thus custom memcpy like + * routines need to be employed. + */ +void *memcpy_to_usbram(void *dest, const void *src, size_t n); +void *memcpy_from_usbram(void *dest, const void *src, size_t n); /* Compute the address inside dedicate SRAM for the USB controller */ #define usb_sram_addr(x) \ |