tools/litex_sim: add support for other sdram types (DDR, LPDDR, DDR2, DDR3)

Right now litex_sim supports only SDR memories because it uses hardcoded
PhySettings. With this change PhySettings will be generated based on
selected sdram type which will allow us to use all the different types
of sdram chips in simulation.

litex/tools/litex_sim.py

@@ -17,7 +17,7 @@ from litex.soc.integration.builder import *
 from litex.soc.cores import uart
 
 from litedram import modules as litedram_modules
-from litedram.common import PhySettings
+from litedram.common import *
 from litedram.phy.model import SDRAMPHYModel
 
 from liteeth.phy.model import LiteEthPHYModel
@@ -62,6 +62,71 @@ class Platform(SimPlatform):
     def __init__(self):
         SimPlatform.__init__(self, "SIM", _io)
 
+# DFI PHY model settings ---------------------------------------------------------------------------
+
+sdram_module_nphases = {
+    "SDR": 1,
+    "DDR": 2,
+    "LPDDR": 2,
+    "DDR2": 2,
+    "DDR3": 4,
+}
+
+def get_sdram_phy_settings(memtype, data_width, clk_freq):
+    nphases = sdram_module_nphases[memtype]
+
+    # Default litex_sim settings
+    if memtype == "SDR":
+        rdphase             = 0
+        wrphase             = 0
+        rdcmdphase          = 0
+        wrcmdphase          = 0
+        cl                  = 2
+        cwl                 = None
+        read_latency        = 4
+        write_latency       = 0
+    # Settings taken from s6ddrphy
+    elif memtype in ["DDR", "LPDDR"]:
+        rdphase             = 0
+        wrphase             = 1
+        rdcmdphase          = 1
+        wrcmdphase          = 0
+        cl                  = 3
+        cwl                 = None
+        read_latency        = 5
+        write_latency       = 0
+    # Settings taken from s7ddrphy
+    elif memtype in ["DDR2", "DDR3"]:
+        tck                 = 2/(2*nphases*clk_freq)
+        cmd_latency         = 0
+        cl, cwl             = get_cl_cw(memtype, tck)
+        cl_sys_latency      = get_sys_latency(nphases, cl)
+        cwl                 = cwl + cmd_latency
+        cwl_sys_latency     = get_sys_latency(nphases, cwl)
+        rdcmdphase, rdphase = get_sys_phases(nphases, cl_sys_latency, cl)
+        wrcmdphase, wrphase = get_sys_phases(nphases, cwl_sys_latency, cwl)
+        read_latency        = 2 + cl_sys_latency + 2 + 3
+        write_latency       = cwl_sys_latency
+
+    sdram_phy_settings = {
+        "nphases": nphases,
+        "rdphase": rdphase,
+        "wrphase": wrphase,
+        "rdcmdphase": rdcmdphase,
+        "wrcmdphase": wrcmdphase,
+        "cl": cl,
+        "cwl": cwl,
+        "read_latency": read_latency,
+        "write_latency": write_latency,
+    }
+
+    return PhySettings(
+        memtype             = memtype,
+        databits            = data_width,
+        dfi_databits        = data_width if memtype == "SDR" else 2*data_width,
+        **sdram_phy_settings,
+    )
+
 # Simulation SoC -----------------------------------------------------------------------------------
 
 class SimSoC(SoCSDRAM):
@@ -101,21 +166,9 @@ class SimSoC(SoCSDRAM):
         if with_sdram:
             sdram_clk_freq   = int(100e6) # FIXME: use 100MHz timings
             sdram_module_cls = getattr(litedram_modules, sdram_module)
-            sdram_module     = sdram_module_cls(sdram_clk_freq, "1:1")
+            sdram_rate       = "1:{}".format(sdram_module_nphases[sdram_module_cls.memtype])
-            assert sdram_module.memtype == "SDR"
+            sdram_module     = sdram_module_cls(sdram_clk_freq, sdram_rate)
-            phy_settings = PhySettings(
+            phy_settings     = get_sdram_phy_settings(sdram_module.memtype, sdram_data_width, sdram_clk_freq)
-                memtype       = "SDR",
-                databits      = sdram_data_width,
-                dfi_databits  = 16,
-                nphases       = 1,
-                rdphase       = 0,
-                wrphase       = 0,
-                rdcmdphase    = 0,
-                wrcmdphase    = 0,
-                cl            = 2,
-                read_latency  = 4,
-                write_latency = 0
-            )
             self.submodules.sdrphy = SDRAMPHYModel(sdram_module, phy_settings)
             self.register_sdram(
                 self.sdrphy,