Add 16-bits, RGB565 FB support in simple-framebuffer

litex/soc/cores/video.py

@@ -606,11 +606,13 @@ class VideoTerminal(Module):
 
 class VideoFrameBuffer(Module, AutoCSR):
     """Video FrameBuffer"""
-    def __init__(self, dram_port, hres=800, vres=600, base=0x00000000, fifo_depth=65536, clock_domain="sys", clock_faster_than_sys=False):
+    def __init__(self, dram_port, hres=800, vres=600, base=0x00000000, fifo_depth=65536, clock_domain="sys", clock_faster_than_sys=False, depth=32):
         self.vtg_sink  = vtg_sink = stream.Endpoint(video_timing_layout)
         self.source    = source   = stream.Endpoint(video_data_layout)
         self.underflow = Signal()
 
+        assert((depth == 32) or (depth == 16))
+
         # # #
 
         # Video DMA.
@@ -618,29 +620,29 @@ class VideoFrameBuffer(Module, AutoCSR):
         self.submodules.dma = LiteDRAMDMAReader(dram_port, fifo_depth=fifo_depth//(dram_port.data_width//8), fifo_buffered=True)
         self.dma.add_csr(
             default_base   = base,
-            default_length = hres*vres*32//8, # 32-bit RGB-444
+            default_length = hres*vres*depth//8, # 32-bit RGB-888 or 16-bit RGB-565
             default_enable = 0,
             default_loop   = 1
         )
 
-        # If DRAM Data Width > 32-bit and Video clock is faster than sys_clk:
+        # If DRAM Data Width > depth and Video clock is faster than sys_clk:
-        if (dram_port.data_width > 32) and clock_faster_than_sys:
+        if (dram_port.data_width > depth) and clock_faster_than_sys:
             # Do Clock Domain Crossing first...
             self.submodules.cdc = stream.ClockDomainCrossing([("data", dram_port.data_width)], cd_from="sys", cd_to=clock_domain)
             self.comb += self.dma.source.connect(self.cdc.sink)
             # ... and then Data-Width Conversion.
-            self.submodules.conv = stream.Converter(dram_port.data_width, 32)
+            self.submodules.conv = stream.Converter(dram_port.data_width, depth)
             self.comb += self.cdc.source.connect(self.conv.sink)
             video_pipe_source = self.conv.source
-        # Elsif DRAM Data Widt < 32-bit or Video clock is slower than sys_clk:
+        # Elsif DRAM Data Width <= depth or Video clock is slower than sys_clk:
         else:
             # Do Data-Width Conversion first...
-            self.submodules.conv = stream.Converter(dram_port.data_width, 32)
+            self.submodules.conv = stream.Converter(dram_port.data_width, depth)
             self.comb += self.dma.source.connect(self.conv.sink)
             # ... and then Clock Domain Crossing.
-            self.submodules.cdc = stream.ClockDomainCrossing([("data", 32)], cd_from="sys", cd_to=clock_domain)
+            self.submodules.cdc = stream.ClockDomainCrossing([("data", depth)], cd_from="sys", cd_to=clock_domain)
             self.comb += self.conv.source.connect(self.cdc.sink)
-            self.comb += If(dram_port.data_width < 32, # FIXME.
+            self.comb += If((dram_port.data_width < depth) and (depth == 32), # FIXME.
                 self.cdc.sink.data[ 0: 8].eq(self.conv.source.data[16:24]),
                 self.cdc.sink.data[16:24].eq(self.conv.source.data[ 0: 8]),
             )
@@ -655,9 +657,15 @@ class VideoFrameBuffer(Module, AutoCSR):
 
             ),
             vtg_sink.connect(source, keep={"de", "hsync", "vsync"}),
+            If(depth == 32,
                source.r.eq(video_pipe_source.data[16:24]),
                source.g.eq(video_pipe_source.data[ 8:16]),
                source.b.eq(video_pipe_source.data[ 0: 8]),
+            ).Else( # depth == 16
+                source.r.eq(Cat(Signal(3, reset = 0), video_pipe_source.data[ 0: 5])),
+                source.g.eq(Cat(Signal(2, reset = 0), video_pipe_source.data[ 5:11])),
+                source.b.eq(Cat(Signal(3, reset = 0), video_pipe_source.data[11:16])),
+            )
         ]
 
         # Underflow.

litex/soc/integration/soc.py

@@ -1784,7 +1784,7 @@ class LiteXSoC(SoC):
         self.comb += vt.source.connect(phy if isinstance(phy, stream.Endpoint) else phy.sink)
 
     # Add Video Framebuffer ------------------------------------------------------------------------
-    def add_video_framebuffer(self, name="video_framebuffer", phy=None, timings="800x600@60Hz", clock_domain="sys"):
+    def add_video_framebuffer(self, name="video_framebuffer", phy=None, timings="800x600@60Hz", clock_domain="sys", depth=32):
         # Imports.
         from litex.soc.cores.video import VideoTimingGenerator, VideoFrameBuffer
 
@@ -1803,7 +1803,8 @@ class LiteXSoC(SoC):
             vres = vres,
             base = base,
             clock_domain          = clock_domain,
-            clock_faster_than_sys = vtg.video_timings["pix_clk"] > self.sys_clk_freq
+            clock_faster_than_sys = vtg.video_timings["pix_clk"] > self.sys_clk_freq,
+            depth = depth
         )
         setattr(self.submodules, name, vfb)
 
@@ -1817,3 +1818,5 @@ class LiteXSoC(SoC):
         self.add_constant("VIDEO_FRAMEBUFFER_BASE", base)
         self.add_constant("VIDEO_FRAMEBUFFER_HRES", hres)
         self.add_constant("VIDEO_FRAMEBUFFER_VRES", vres)
+        self.add_constant("VIDEO_FRAMEBUFFER_DEPTH", depth)
+

litex/tools/litex_json2dts_linux.py

@@ -211,7 +211,7 @@ def generate_dts(d, initrd_start=None, initrd_size=None, initrd=None, root_devic
             }};
 """.format(
     framebuffer_base = d["constants"]["video_framebuffer_base"],
-    framebuffer_size = (d["constants"]["video_framebuffer_hres"] * d["constants"]["video_framebuffer_vres"] * 4))
+    framebuffer_size = (d["constants"]["video_framebuffer_hres"] * d["constants"]["video_framebuffer_vres"] * (d["constants"]["video_framebuffer_depth"]//8)))
 
         dts += """
         };
@@ -491,6 +491,10 @@ def generate_dts(d, initrd_start=None, initrd_size=None, initrd=None, root_devic
         framebuffer_base   = d["constants"]["video_framebuffer_base"]
         framebuffer_width  = d["constants"]["video_framebuffer_hres"]
         framebuffer_height = d["constants"]["video_framebuffer_vres"]
+        framebuffer_depth  = d["constants"]["video_framebuffer_depth"]
+        framebuffer_format = "a8b8g8r8"
+        if (framebuffer_depth == 16):
+            framebuffer_format = "r5g6b5"
         dts += """
             framebuffer0: framebuffer@{framebuffer_base:x} {{
                 compatible = "simple-framebuffer";
@@ -498,14 +502,15 @@ def generate_dts(d, initrd_start=None, initrd_size=None, initrd=None, root_devic
                 width = <{framebuffer_width}>;
                 height = <{framebuffer_height}>;
                 stride = <{framebuffer_stride}>;
-                format = "a8b8g8r8";
+                format = "{framebuffer_format}";
             }};
 """.format(
     framebuffer_base   = framebuffer_base,
     framebuffer_width  = framebuffer_width,
     framebuffer_height = framebuffer_height,
-    framebuffer_size   = framebuffer_width * framebuffer_height * 4,
+    framebuffer_size   = framebuffer_width * framebuffer_height * (framebuffer_depth//8),
-    framebuffer_stride = framebuffer_width * 4)
+    framebuffer_stride = framebuffer_width * (framebuffer_depth//8),
+    framebuffer_format = framebuffer_format)
 
     # ICAP Bitstream -------------------------------------------------------------------------------