From ff67781f11953e405f1b8f3e63db4d47a9824e53 Mon Sep 17 00:00:00 2001 From: Florent Kermarrec Date: Fri, 28 Jul 2023 09:26:53 +0200 Subject: [PATCH] interconnect/axi/axi_common: Document constants. --- litex/soc/interconnect/axi/axi_common.py | 31 ++++++++++++------------ 1 file changed, 16 insertions(+), 15 deletions(-) diff --git a/litex/soc/interconnect/axi/axi_common.py b/litex/soc/interconnect/axi/axi_common.py index f050b1c7d..4ec78b208 100644 --- a/litex/soc/interconnect/axi/axi_common.py +++ b/litex/soc/interconnect/axi/axi_common.py @@ -19,24 +19,25 @@ from litex.soc.interconnect import stream # AXI Constants ------------------------------------------------------------------------------------ -BURST_FIXED = 0b00 -BURST_INCR = 0b01 -BURST_WRAP = 0b10 -BURST_RESERVED = 0b11 +BURST_FIXED = 0b00 # FIXED : No address increment in burst. +BURST_INCR = 0b01 # INCR : Increment address per transfer in burst. +BURST_WRAP = 0b10 # WRAP : Wrap address back to boundary after set transfers. +BURST_RESERVED = 0b11 # RESERVED : Future use. -RESP_OKAY = 0b00 -RESP_EXOKAY = 0b01 -RESP_SLVERR = 0b10 -RESP_DECERR = 0b11 +RESP_OKAY = 0b00 # OKAY : Operation completed successfully. +RESP_EXOKAY = 0b01 # EXOKAY : Operation success, exclusive access granted. +RESP_SLVERR = 0b10 # SLVERR : Slave not responding/cannot complete request. +RESP_DECERR = 0b11 # DECERR : Decoding error occurred, operation not routed to a slave. +# AXI transaction size (AXSIZE) constants (left: bytes, right: AXI representation). AXSIZE = { - 1 : 0b000, - 2 : 0b001, - 4 : 0b010, - 8 : 0b011, - 16 : 0b100, - 32 : 0b110, - 64 : 0b111, + 1 : 0b000, # 1-byte transaction. + 2 : 0b001, # 2-byte transaction. + 4 : 0b010, # 4-byte transaction. + 8 : 0b011, # 8-byte transaction. + 16 : 0b100, # 16-byte transaction. + 32 : 0b110, # 32-byte transaction. + 64 : 0b111, # 64-byte transaction. } # AXI Connection Helpers ---------------------------------------------------------------------------