FIFO is limited to 64 bytes yet MCU is capable of transmitting
larger packets provided that FIFO will be filled on the fly
and USB_USB_TXCx_REG_USB_LAST_Msk bit is set after FIFO is
filled with all the data that should be transmitted.
This change allows to use FIFO level warning interrupt to fill
FIFO. When DMA is available it will be used instead of interrupts.
Some function names were changed to better reflect what each function
does.
Closing endpoints can be important when there are alternate
instances. This adds functionality of closing endpoints
similar to what exists in other drivers.
Internal FIFO for each endpoint is limited to 64 bytes.
It is possible to have longer packets if respective FIFO
is read during actual packet transmission.
This change updates receive data path to allow packets (and
endpoint size) larger then 64 bytes.
If DMA is not used yet DMA is setup for reception of big packets.
If DMA is already assigned to some transfer, code enables FIFO level
warning interrupts and tries to read data before FIFO is filled up.
ISO endpoints were not covered so far by the driver code.
This adds support for ISO IN and OUT endpoint handling.
Registers for ISO IN(OUT) endpoints are placed just after normal IN(OUT)
so in some cases common code could be used for handling all type of
transfers.
Generally code synchronizes ISO endpoint handling to SOF interrupt.
This code does not change the way of how non-ISO endpoints are treated.
Code uses strategy outlined in nRF52840 Produce Specification v1.0
sections 6.35.11.1 and 6.35.11.2.
Closing endpoints can be important when there are alternate
instances. This adds functionality of closing endpoints
similar to what exists in other drivers.
Currently number of endpoints was hard coded to 8.
NRF52 has 9 IN and 9 OUT endpoints.
ISO endpoints are 0x08 and 0x88 and without this change those
two ISO endpoint could not be used.
Current implementation always sets odd/even bit for ISO transactions.
This is a good strategy only if interval is 1.
For ISO endpoint interval in (micro)frames is computed as
2^(interval-1), which means that odd/frame number should stay
same for interval values > 1.
With this change only when interval is 1 odd/even bit is modified.
hathach