From bccabdc5bac0b88d464d80a3b9bcdf2d8ae0f606 Mon Sep 17 00:00:00 2001
From: "Peter D. Gray" <peter@conalgo.com>
Date: Thu, 20 Jul 2023 10:42:38 -0400
Subject: [PATCH] working rad

---
 shared/gpu.py | 159 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)
 create mode 100644 shared/gpu.py

diff --git a/shared/gpu.py b/shared/gpu.py
new file mode 100644
index 00000000..5099cad7
--- /dev/null
+++ b/shared/gpu.py
@@ -0,0 +1,159 @@
+# (c) Copyright 2023 by Coinkite Inc. This file is covered by license found in COPYING-CC.
+#
+# gpu.py - GPU co-processor access and support.
+#
+# - see notes in misc/gpu/README.md
+# - bl = Bootloader, provided by ST Micro in ROM of chip
+# - useful: import gpu; g=gpu.GPUAccess(); g.enter_bl()
+#
+import utime, struct
+import uasyncio as asyncio
+from utils import B2A
+from machine import Pin
+
+# boot loader ROM response to this I2C address
+BL_ADDR = const(0x64)
+
+BL_ACK = b'y'       # 0x79
+BL_NACK = b'\x1f'
+BL_BUSY = b'v'      # 0x76
+
+def add_xor_check(lst):
+    # byte-wise xor over list of bytes (used as a very weak checksum in BL)
+    rv = 0x0
+    for b in lst:
+        rv ^= b
+    return bytes(lst + bytes([rv]))
+
+class GPUAccess:
+    def __init__(self):
+        # much sharing/overlap in these pins!
+        self.g_reset = Pin('G_RESET', mode=Pin.OPEN_DRAIN, pull=Pin.PULL_UP)
+        #self.g_boot0 = Pin('G_SWCLK_B0', mode=Pin.OPEN_DRAIN, pull=Pin.PULL_NONE)
+        self.g_boot0 = Pin('G_SWCLK_B0', mode=Pin.IN)
+        self.g_ctrl = Pin('G_CTRL', mode=Pin.IN)
+
+        from machine import I2C
+        self.i2c = I2C(1, freq=400000)      # same bus & speed as nfc.py
+
+    def bl_cmd_read(self, cmd, expect_len, addr=None, arg2=None, no_final=False):
+        # send a one-byte command to bootloader ROM and get response
+        # - need len to expect, because limitations of hard i2c on this setup
+        i2c = self.i2c
+
+        self._send_cmd(cmd)
+
+        if addr is not None:
+            if isinstance(addr, int):
+                # write 4 bytes of address
+                qq = add_xor_check(struct.pack('>I', addr))
+            else:
+                qq = bytes(addr)
+
+            print('wr ' + B2A(qq))
+            i2c.writeto(BL_ADDR, qq)
+
+            resp = i2c.readfrom(BL_ADDR, 1)
+            if resp != BL_ACK:
+                raise ValueError('bad addr ' + B2A(resp))
+
+        if arg2 is not None:
+            # XXX tbd
+            # write 1 bytes of address
+            i2c.writeto(BL_ADDR, bytes([arg2, 0xff ^ arg2]))
+            resp = i2c.readfrom(BL_ADDR, 1)
+            if resp != BL_ACK:
+                raise ValueError('bad arg2')
+
+        # for some commands, first byte of response is length and it can vary
+        # - however, they are inconsistent on how they count that and not
+        #   all commands use it, etc.
+        # - tried and failed to check/handle the length here; now caller's problem
+        rv = i2c.readfrom(BL_ADDR, expect_len) 
+
+        if not no_final:
+            # final ack/nack
+            resp = i2c.readfrom(BL_ADDR, 1)
+            if resp != BL_ACK:
+                raise ValueError(resp)
+
+        return rv
+
+    def _wait_done(self):
+        for retry in range(100):
+            try:
+                resp = self.i2c.readfrom(BL_ADDR, 1)
+            except OSError:     # ENODEV
+                print('recover')
+                utime.sleep_ms(50)
+                continue
+
+            if resp != BL_BUSY:
+                break
+
+            print('busy')
+            utime.sleep_ms(50)
+
+        return resp
+
+    def _send_cmd(self, cmd):
+        # do just the cmd + ack part
+        self.i2c.writeto(BL_ADDR, bytes([cmd, 0xff ^ cmd]))
+        resp = self.i2c.readfrom(BL_ADDR, 1)
+        if resp != BL_ACK:
+            raise ValueError('unknown command')
+
+    def bl_doit(self, cmd, arg):
+        # send a one-byte command and and argument, wait until done
+        self._send_cmd(cmd)
+
+        i2c.writeto(BL_ADDR, add_xor_check(arg))
+
+        return self._wait_done()
+
+    def bl_double_ack(self, cmd):
+        # some commands need two acks because they do stuff during that time?
+        self._send_cmd(cmd)
+        resp = self._wait_done()
+        if resp == BL_ACK:
+            return self._wait_done()
+        return resp
+
+    def reset(self):
+        # pulse reset and let it run
+        self.g_reset(0)
+        self.g_reset(1)
+
+    def enter_bl(self):
+        # get it into bootloader
+        self.g_reset(0)
+        self.g_boot0.init(mode=Pin.OPEN_DRAIN, pull=Pin.PULL_UP)
+        self.g_reset(1)
+        self.g_boot0.init(mode=Pin.IN)
+
+    def get_version(self):
+        # assume already in bootloader
+        return self.bl_cmd_read(0x0, 20)
+
+    def bulk_erase(self):
+        # "No-Stretch Erase Memory" with 0xFFFF arg = "global mass erase"
+        return self.bl_doit(0x45, b'\xff\xff') == BL_ACK
+
+    def readout_unprotect(self):
+        # "No-Stretch Readout Unprotect" -- may wipe chip in process?
+        return self.bl_double_ack(0x93)
+
+    def readout_protect(self):
+        # "No-Stretch Readout Protect" 
+        return self.bl_double_ack(0x83)
+
+    def read_at(self, addr=0x0800_0000, ln=16):
+        # read memory, but address must be "correct" and mapped, which is undocumented
+        # - need not be aligned, up to 255
+        # - 0x1fff0cd0 also fun
+        # - some weird trailing byte, it's not an ACK/NACK/xor but needs reading
+        assert ln < 256
+        return self.bl_cmd_read(0x11, ln+1, addr=addr, arg2=ln, no_final=True)[0:ln]
+
+
+# EOF