From 04548a2c41a7b8d7c892ecd44e45783cfd3172b7 Mon Sep 17 00:00:00 2001
From: Andrey Miroshnikov <andrey@technepisteme.xyz>
Date: Thu, 6 Jan 2022 23:14:19 +0000
Subject: [PATCH] Adding simple_gpio from soc repo, not modified yet.

---
 src/spec/simple_gpio.py | 125 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 src/spec/simple_gpio.py

diff --git a/src/spec/simple_gpio.py b/src/spec/simple_gpio.py
new file mode 100644
index 0000000..86afebe
--- /dev/null
+++ b/src/spec/simple_gpio.py
@@ -0,0 +1,125 @@
+"""Simple GPIO peripheral on wishbone
+
+This is an extremely simple GPIO peripheral intended for use in XICS
+testing, however it could also be used as an actual GPIO peripheral
+"""
+
+from nmigen import Elaboratable, Module, Signal, Record, Array
+from nmigen.utils import log2_int
+from nmigen.cli import rtlil
+from soc.minerva.wishbone import make_wb_layout
+from nmutil.util import wrap
+from soc.bus.test.wb_rw import wb_read, wb_write
+
+cxxsim = False
+if cxxsim:
+    from nmigen.sim.cxxsim import Simulator, Settle
+else:
+    from nmigen.back.pysim import Simulator, Settle
+
+
+class SimpleGPIO(Elaboratable):
+
+    def __init__(self, n_gpio=16):
+        self.n_gpio = n_gpio
+        class Spec: pass
+        spec = Spec()
+        spec.addr_wid = 30
+        spec.mask_wid = 4
+        spec.reg_wid = 32
+        self.bus = Record(make_wb_layout(spec), name="gpio_wb")
+        self.gpio_o = Signal(n_gpio)
+
+    def elaborate(self, platform):
+        m = Module()
+        comb, sync = m.d.comb, m.d.sync
+
+        bus = self.bus
+        wb_rd_data = bus.dat_r
+        wb_wr_data = bus.dat_w
+        wb_ack = bus.ack
+        gpio_o = self.gpio_o
+
+        comb += wb_ack.eq(0)
+
+        gpio_addr = Signal(log2_int(self.n_gpio))
+        gpio_a = Array(list(gpio_o))
+
+        with m.If(bus.cyc & bus.stb):
+            comb += wb_ack.eq(1) # always ack
+            comb += gpio_addr.eq(bus.adr)
+            with m.If(bus.we): # write
+                sync += gpio_a[gpio_addr].eq(wb_wr_data[0])
+            with m.Else(): # read
+                comb += wb_rd_data.eq(gpio_a[gpio_addr])
+
+        return m
+
+    def __iter__(self):
+        for field in self.bus.fields.values():
+            yield field
+        yield self.gpio_o
+
+    def ports(self):
+        return list(self)
+
+
+
+def read_gpio(gpio, addr):
+    data = yield from wb_read(gpio.bus, addr)
+    print ("gpio%d" % addr, hex(data), bin(data))
+    return data
+
+
+def sim_gpio(gpio):
+
+    # GPIO0
+    data = yield from read_gpio(gpio, 0) # read gpio addr  0
+    assert data == 0
+    
+    yield from wb_write(gpio.bus, 0, 1) # write gpio addr 0
+
+    data = yield from read_gpio(gpio, 0) # read gpio addr  0
+    assert data == 1
+
+    # GPIO1
+    data = yield from read_gpio(gpio, 1) # read gpio addr  1
+    assert data == 0
+    
+    yield from wb_write(gpio.bus, 1, 1) # write gpio addr 1
+
+    data = yield from read_gpio(gpio, 1) # read gpio addr  1
+    assert data == 1
+
+    # GPIO0
+    data = yield from read_gpio(gpio, 0) # read gpio addr  0
+    assert data == 1
+    
+    yield from wb_write(gpio.bus, 0, 0) # write gpio addr 0
+
+    data = yield from read_gpio(gpio, 0) # read gpio addr  0
+    assert data == 0
+
+
+def test_gpio():
+
+    dut = SimpleGPIO()
+    vl = rtlil.convert(dut, ports=dut.ports())
+    with open("test_gpio.il", "w") as f:
+        f.write(vl)
+
+    m = Module()
+    m.submodules.xics_icp = dut
+
+    sim = Simulator(m)
+    sim.add_clock(1e-6)
+
+    sim.add_sync_process(wrap(sim_gpio(dut)))
+    sim_writer = sim.write_vcd('test_gpio.vcd')
+    with sim_writer:
+        sim.run()
+
+
+if __name__ == '__main__':
+    test_gpio()
+
-- 
2.30.2