stm32/rfcore: Intercept addr-resolution HCI cmd to work around BLE bug.

The STM32WB has a problem when address resolution is enabled: under certain
conditions the MCU can get into a state where it draws an additional 10mA
or so and eventually ends up with a broken BLE RX path in the silicon.  A
simple way to reproduce this is to enable address resolution (which is the
default for NimBLE) and start the device advertising.  If there is enough
BLE activity in the vicinity then the device will at some point enter the
bad state and, if left long enough, will have permanent BLE RX damage.

STMicroelectronics are aware of this issue.  The only known workaround at
this stage is to not enable address resolution, which is implemented by
this commit.

Work done in collaboration with Jim Mussared aka @jimmo.

Signed-off-by: Damien George <damien@micropython.org>

ports/stm32/rfcore.c

@@ -610,6 +610,24 @@ void rfcore_ble_hci_cmd(size_t len, const uint8_t *src) {
     tl_list_node_t *n;
     uint32_t ch;
     if (src[0] == HCI_KIND_BT_CMD) {
+        // The STM32WB has a problem when address resolution is enabled: under certain
+        // conditions the MCU can get into a state where it draws an additional 10mA
+        // or so and eventually ends up with a broken BLE RX path in the silicon.  A
+        // simple way to reproduce this is to enable address resolution (which is the
+        // default for NimBLE) and start the device advertising.  If there is enough
+        // BLE activity in the vicinity then the device will at some point enter the
+        // bad state and, if left long enough, will have permanent BLE RX damage.
+        //
+        // STMicroelectronics are aware of this issue.  The only known workaround at
+        // this stage is to not enable address resolution.  We do that here by
+        // intercepting any command that enables address resolution and convert it
+        // into a command that disables address resolution.
+        //
+        // OGF=0x08 OCF=0x002d HCI_LE_Set_Address_Resolution_Enable
+        if (len == 5 && memcmp(src + 1, "\x2d\x20\x01\x01", 4) == 0) {
+            src = (const uint8_t *)"\x01\x2d\x20\x01\x00";
+        }
+
         n = (tl_list_node_t *)&ipcc_membuf_ble_cmd_buf[0];
         ch = IPCC_CH_BLE;
     } else if (src[0] == HCI_KIND_BT_ACL) {