Spit xbar into two levels

Attempt to reduce the depth of xbar logic on critical timing paths
to/from the HyperRAM/SRAM by moving most peripherals
from the main cross-bar to a new "peri" (peripheral) sub-crossbar.
Keeps addresses the same, but some few devices have increased
access latency due to being moved to xbar_peri or to improve QoR.

Blocks with increased access latency: timer, system_info, & hw_rev.

Blocks with decreased access latency: plic.

Author: elliotb-lowrisc

.gitattributes

@@ -2,11 +2,14 @@
 # Licensed under the Apache License, Version 2.0, see LICENSE for details.
 # SPDX-License-Identifier: Apache-2.0
 data/xbar_main_generated.hjson linguist-generated=true
+data/xbar_peri_generated.hjson linguist-generated=true
 doc/ip/pinmux/README.md linguist-generated=true
 rtl/bus/sonata_xbar_main.sv linguist-generated=true
 rtl/bus/tl_main_pkg.sv linguist-generated=true
+rtl/bus/tl_peri_pkg.sv linguist-generated=true
 rtl/bus/tl_ifetch_pkg.sv linguist-generated=true
 rtl/bus/xbar_main.sv linguist-generated=true
+rtl/bus/xbar_peri.sv linguist-generated=true
 rtl/bus/xbar_ifetch.sv linguist-generated=true
 rtl/system/pinmux.sv linguist-generated=true
 rtl/system/sonata_pkg.sv linguist-generated=true

data/top_config.toml

@@ -11,14 +11,15 @@ ios = [
 ]
 memory_start = 0x80000040
 memory_size  = 0x00000040
+which_xbar = "peri"
 
 [[blocks]]
 name = "pwm"
 instances = 1
 ios = [{ name = "out", type = "output", length = 7 }]
 memory_start = 0x80001000
 memory_size  = 0x00001000
-xbar = { pipeline = "true", req_fifo_pass = "false", rsp_fifo_pass = "false" }
+which_xbar = "peri"
 
 [[blocks]]
 name = "uart"
@@ -29,7 +30,7 @@ ios = [
 ]
 memory_start = 0x80100000
 memory_size  = 0x00001000
-xbar = { pipeline = "true", req_fifo_pass = "false", rsp_fifo_pass = "false" }
+which_xbar = "peri"
 
 [[blocks]]
 name = "i2c"
@@ -41,6 +42,7 @@ ios = [
 memory_start = 0x80200000
 memory_size  = 0x00001000
 xbar = { pipeline = "true", req_fifo_pass = "false", rsp_fifo_pass = "false" }
+which_xbar = "main"
 
 [[blocks]]
 name = "spi"
@@ -53,6 +55,7 @@ ios = [
 ]
 memory_start = 0x80303000
 memory_size  = 0x00001000
+which_xbar = "main"
 
 # UARTS
 [[pins]]

data/xbar_main.hjson

@@ -61,87 +61,18 @@
         size_byte: "0x00004000",
       }],
     },
-    { name:  "gpio", // General purpose input and output
+    { name:  "peri",
       type:  "device",
       clock: "clk_sys_i",
       reset: "rst_sys_ni",
-      req_fifo_pass: false,
-      rsp_fifo_pass: false,
       xbar:  false,
       addr_range: [{
         base_addr: "0x80000000",
-        size_byte: "0x00001000",
-      }],
-      pipeline: true,
-    },
-    { name:  "pinmux", // Pin multiplexer
-      type:  "device",
-      clock: "clk_sys_i",
-      reset: "rst_sys_ni",
-      req_fifo_pass: false,
-      rsp_fifo_pass: false,
-      xbar:  false,
-      addr_range: [{
-        base_addr: "0x80005000",
-        size_byte: "0x00001000",
-      }],
-      pipeline: true,
-    },
-    { name:  "rgbled_ctrl", // RGB LED Controller
-      type:  "device",
-      clock: "clk_sys_i",
-      reset: "rst_sys_ni",
-      req_fifo_pass: false,
-      rsp_fifo_pass: false,
-      xbar:  false,
-      addr_range: [{
-        base_addr: "0x80009000",
-        size_byte: "0x00001000",
+        size_byte: "0x00200000",
       }],
       pipeline: true,
-    },
-    { name:  "hw_rev", // Hardware revoker control register
-      type:  "device",
-      clock: "clk_sys_i",
-      reset: "rst_sys_ni",
-      xbar:  false,
-      addr_range: [{
-        base_addr: "0x8000A000",
-        size_byte: "0x00001000",
-      }],
-    },
-    { name:  "xadc", // XADC
-      type:  "device",
-      clock: "clk_sys_i",
-      reset: "rst_sys_ni",
       req_fifo_pass: false,
       rsp_fifo_pass: false,
-      xbar:  false,
-      addr_range: [{
-        base_addr: "0x8000B000",
-        size_byte: "0x00001000",
-      }],
-      pipeline: true,
-    },
-    { name:  "system_info", // System information
-      type:  "device",
-      clock: "clk_sys_i",
-      reset: "rst_sys_ni",
-      xbar:  false,
-      addr_range: [{
-        base_addr: "0x8000C000",
-        size_byte: "0x00001000",
-      }],
-    },
-    { name:  "timer", // Interrupt timer
-      type:  "device",
-      clock: "clk_sys_i",
-      reset: "rst_sys_ni",
-      xbar:  false,
-      addr_range: [{
-        base_addr: "0x80040000",
-        size_byte: "0x00010000",
-      }],
     },
     { name:  "spi_board",
       type:  "device",
@@ -173,8 +104,12 @@
         size_byte: "0x00001000",
       }],
     },
+    // I^2C devices included here instead of in peri only because
+    // address range sizes must be a power of two.
+    // We can easily tolerate an extra cycle of access latency to them,
+    // so add pipelining to allow them to be placed further away physically.
     % for block in config.blocks:
-    % if not block.name == "gpio":
+    % if block.which_xbar == "main":
     % for i in range(block.instances):
     { name:  "${f"{block.name}{i}"}",
       type:  "device",
@@ -206,34 +141,25 @@
       type:  "device",
       clock: "clk_sys_i",
       reset: "rst_sys_ni",
-      req_fifo_pass: false,
-      rsp_fifo_pass: false,
       xbar:  false,
       addr_range: [{
         // This block is overaligned to 0x0800_0000 bytes since OpenTitan RV_PLIC block expects it.
         base_addr: "0x88000000",
         size_byte: "0x04000000",
       }],
-      pipeline: true,
     },
   ],
   connections: {
     ibex_lsu: [
       "sram",
       "hyperram",
       "rev_tag",
-      "gpio",
-      "pinmux",
-      "system_info",
-      "rgbled_ctrl",
-      "hw_rev",
-      "xadc",
-      "timer",
+      "peri",
       "spi_board",
       "spi_lcd",
       "spi_ethmac",
       % for block in config.blocks:
-      % if not block.name == "gpio":
+      % if block.which_xbar == "main":
       % for i in range(block.instances):
       "${f"{block.name}{i}"}",
       % endfor