maksyuki
270343a891
- Updated filelist to include I2S related files. - Enhanced formal file generation script to support I2S target. - Introduced I2S formal design and properties for verification. - Modified formal makefile to include I2S targets and source files. - Added I2S related source files to software build. - Updated style audit to include I2S files. - Implemented I2S helper functions in C tests. - Created I2S testbench for RTL simulation. - Added regression test for I2S controller functionality.
2.3 KiB
AXI4-Stream Peripheral Data Paths
The Mini SoC uses 32-bit AXI4-Stream links for high-rate peripheral data that does not need an address on every word. APB4 remains the register configuration plane. The active stream endpoints are DMA to I2S TX, I2S RX to DMA, and DVP RX to DMA. UART, I2C, and WS2812 retain their existing APB4 FIFO data registers.
Interface Contract
All three links use DATA_WIDTH=32, one-bit ID, destination, and user fields,
and the system clock/reset. TKEEP and TSTRB are 4'hF; the current I2S and
DVP data paths always transfer complete words. DMA holds TDATA, TKEEP,
TSTRB, and TLAST stable while TVALID is high and TREADY is low. A word
is consumed only on a TVALID && TREADY clock edge.
DMA asserts TLAST on the final programmed I2S TX word. I2S RX and DVP do not
currently provide a packet boundary to DMA, so DMA terminates their transfers
using its programmed XFERLEN; incoming TLAST is informational and ignored.
IDs, destinations, and user sidebands are currently zero.
Configuration and PIO Fallback
I2S register offset 0x00C is STREAM_CTRL: bit 0 selects AXI4-Stream as the
TX FIFO producer and bit 1 selects AXI4-Stream as the RX FIFO consumer. A clear
bit preserves the existing TXDATA or RXDATA PIO behavior. Software must not
change a stream-select bit while that direction is active. TXDATA is 0x01C
and RXDATA is 0x020.
DVP register offset 0x0C is STREAM_CTRL: bit 0 selects AXI4-Stream as the
RX FIFO consumer. When clear, reads of RXDATA retain the existing pop
behavior. When set, RXDATA reads do not pop the FIFO.
DMA modes 1 and 2 use the I2S TX and RX stream links. Mode 11 uses DVP RX. The source address is unused for stream RX modes, and the destination address is unused for I2S TX, but the current software API still requires valid nonzero addresses for a uniform descriptor contract. DMA writes received stream words to AXI4 memory and reads I2S TX words from AXI4 memory.
Verification Boundary
The DMA directed test covers stream TX backpressure, two-word stream RX to memory, exact transfer length, bus errors, and retained RIB burst behavior. The I2S and DVP FIFO tests continue to cover PIO mode. Physical audio and camera clock-domain behavior remains controller-specific and must be verified with board-level timing and device models.