[rcp] add enable-coex switch (#7675)

This commit adds a new option of radio url to enable/disable RCP coex
feature on boot without changing the RCP firmware.

src/posix/platform/radio.cpp

@@ -166,6 +166,15 @@ void Radio::Init(void)
         VerifyOrDie(str == nullptr, OT_EXIT_INVALID_ARGUMENTS);
     }
 #endif // OPENTHREAD_POSIX_CONFIG_MAX_POWER_TABLE_ENABLE
+#if OPENTHREAD_CONFIG_PLATFORM_RADIO_COEX_ENABLE
+    {
+        const char *enableCoex = mRadioUrl.GetValue("enable-coex");
+        if (enableCoex != nullptr)
+        {
+            SuccessOrDie(sRadioSpinel.SetCoexEnabled(enableCoex[0] != '0'));
+        }
+    }
+#endif // OPENTHREAD_CONFIG_PLATFORM_RADIO_COEX_ENABLE
 }
 
 } // namespace Posix

src/posix/platform/radio_url.cpp

@@ -91,6 +91,8 @@ const char *otSysGetRadioUrlHelpString(void)
     return "RadioURL:\n" OT_RADIO_URL_HELP_BUS OT_RADIO_URL_HELP_MAX_POWER_TABLE
            "    region[=region-code]          Set the radio's region code.\n"
            "    cca-threshold[=dbm]           Set the radio's CCA ED threshold in dBm measured at antenna connector.\n"
+           "    enable-coex[=1|0]             If not specified, RCP coex operates with its default configuration.\n"
+           "                                  Disable coex with 0, and enable it with other values.\n"
            "    fem-lnagain[=dbm]             Set the Rx LNA gain in dBm of the external FEM.\n"
            "    ncp-dataset                   Retrieve dataset from ncp.\n"
            "    no-reset                      Do not send Spinel reset command to RCP on initialization.\n"

tests/scripts/expect/posix-url-enable-coex.exp

@@ -0,0 +1,42 @@
+#!/usr/bin/expect -f
+#
+#  Copyright (c) 2022, The OpenThread Authors.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#  1. Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#  2. Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+#  3. Neither the name of the copyright holder nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+#  POSSIBILITY OF SUCH DAMAGE.
+#
+
+source "tests/scripts/expect/_common.exp"
+
+spawn_node 1 "rcp" "spinel+hdlc+uart://$env(OT_SIMULATION_APPS)/ncp/ot-rcp?enable-coex&forkpty-arg=1"
+send "coex\n"
+expect_line "Enabled"
+expect_line "Done"
+dispose_node 1
+
+spawn_node 1 "rcp" "spinel+hdlc+uart://$env(OT_SIMULATION_APPS)/ncp/ot-rcp?enable-coex=0&forkpty-arg=1"
+send "coex\n"
+expect_line "Disabled"
+expect_line "Done"
+dispose_node 1