Merge pull request #862 from pguyot/w40/picow-networking-add-ap-connection

Add AP mode support for Pico-W

Add the ability to configure the Pico-W wireless chipset in AP mode. There is
no DHCP server yet and stations cannot obtain an IP. Also it is possible to
configure the network driver in AP+STA mode, however this does not work. It is
still unclear whether this is a limitation of the chipset.

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

examples/erlang/rp2040/CMakeLists.txt

@@ -27,3 +27,4 @@ pack_uf2(pico_blink pico_blink)
 pack_uf2(pico_rtc pico_rtc)
 pack_uf2(picow_blink picow_blink)
 pack_uf2(picow_wifi_sta picow_wifi_sta)
+pack_uf2(picow_wifi_ap picow_wifi_ap)

examples/erlang/rp2040/picow_wifi_ap.erl

@@ -0,0 +1,56 @@
+%
+% This file is part of AtomVM.
+%
+% Copyright 2023 Paul Guyot <[email protected]>
+%
+% Licensed under the Apache License, Version 2.0 (the "License");
+% you may not use this file except in compliance with the License.
+% You may obtain a copy of the License at
+%
+%    http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS,
+% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+% See the License for the specific language governing permissions and
+% limitations under the License.
+%
+% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%
+
+-module(picow_wifi_ap).
+
+-export([start/0]).
+
+start() ->
+    Config = [
+        {ap, [
+            %% If an SSID is not specified, AtomVM will default to atomvm-<hexmac>
+            %% where <hexmac> is the hexadecimal representation of the factory-supplied
+            %% MAC address of the Pico-W device.
+            %% If a password is not specified, the AP network will be open, with
+            %% no encryption or authentication (strongly discouraged)
+            {ap_started, fun ap_started/0},
+            {sta_connected, fun sta_connected/1},
+            {sta_ip_assigned, fun sta_ip_assigned/1},
+            {sta_disconnected, fun sta_disconnected/1}
+        ]}
+    ],
+    case network:start(Config) of
+        {ok, _Pid} ->
+            timer:sleep(infinity);
+        Error ->
+            erlang:display(Error)
+    end.
+
+ap_started() ->
+    io:format("AP started.\n").
+
+sta_connected(Mac) ->
+    io:format("STA connected with mac ~w\n", [Mac]).
+
+sta_disconnected(Mac) ->
+    io:format("STA disconnected with mac ~w\n", [Mac]).
+
+sta_ip_assigned(Address) ->
+    io:format("STA assigned address ~p\n", [Address]).

src/platforms/rp2040/pico_sdk_import.cmake

@@ -58,14 +58,14 @@ if (NOT PICO_SDK_PATH)
             FetchContent_Declare(
                     pico_sdk
                     GIT_REPOSITORY https://github.com/pguyot/pico-sdk   # revert to raspberrypi once PR 1101 is merged
-                    GIT_TAG v1.5.1+conditional-variables                # revert to master once PR 1101 is merged
+                    GIT_TAG v1.5.1+conditional-variables+cyw43-assoc-callback # revert to master once pico-sdk PR 1101 is merged + cyw43-driver PR 91
                     GIT_SUBMODULES_RECURSE FALSE
             )
         else ()
             FetchContent_Declare(
                     pico_sdk
                     GIT_REPOSITORY https://github.com/pguyot/pico-sdk   # revert to raspberrypi once PR 1101 is merged
-                    GIT_TAG v1.5.1+conditional-variables                # revert to master once PR 1101 is merged
+                    GIT_TAG v1.5.1+conditional-variables+cyw43-assoc-callback # revert to master once pico-sdk PR 1101 is merged + cyw43-driver PR 91
             )
         endif ()
 

src/platforms/rp2040/src/lib/lwipopts.h

@@ -48,6 +48,7 @@
 #define LWIP_NETIF_LINK_CALLBACK 1
 #define LWIP_NETIF_HOSTNAME 1
 #define LWIP_NETCONN 0
+#define CYW43_ASSOC_CALLBACK 1
 #define MEM_STATS 0
 #define SYS_STATS 0
 #define MEMP_STATS 0

src/platforms/rp2040/src/lib/networkdriver.c

@@ -38,6 +38,9 @@
 #define PORT_REPLY_SIZE (TUPLE_SIZE(2) + REF_SIZE)
 
 static const char *const ap_atom = ATOM_STR("\x2", "ap");
+static const char *const ap_sta_connected_atom = ATOM_STR("\x10", "ap_sta_connected");
+static const char *const ap_sta_disconnected_atom = ATOM_STR("\x13", "ap_sta_disconnected");
+static const char *const ap_started_atom = ATOM_STR("\xA", "ap_started");
 static const char *const psk_atom = ATOM_STR("\x3", "psk");
 static const char *const ssid_atom = ATOM_STR("\x4", "ssid");
 static const char *const sta_atom = ATOM_STR("\x3", "sta");
@@ -63,13 +66,16 @@ struct NetworkDriverData
     uint32_t owner_process_id;
     uint64_t ref_ticks;
     int link_status;
+    int stas_count;
+    uint8_t *stas_mac;
 };
 
 // Callbacks do not allow for user data
 // netif->state is actually pointing to &cyw43_state
 static struct NetworkDriverData *driver_data;
 
 static void network_driver_netif_status_cb(struct netif *netif);
+static void network_driver_cyw43_assoc_cb(bool assoc);
 
 static term tuple_from_addr(Heap *heap, uint32_t addr)
 {
@@ -129,6 +135,38 @@ static void send_got_ip(struct netif *netif)
     END_WITH_STACK_HEAP(heap, driver_data->global);
 }
 
+static void send_ap_started()
+{
+    // {Ref, ap_started}
+    BEGIN_WITH_STACK_HEAP(PORT_REPLY_SIZE, heap);
+    {
+        send_term(&heap, globalcontext_make_atom(driver_data->global, ap_started_atom));
+    }
+    END_WITH_STACK_HEAP(heap, driver_data->global);
+}
+
+static void send_atom_mac(term atom, uint8_t *mac)
+{
+    // {Ref, {ap_connected | ap_disconnected, <<1,2,3,4,5,6>>}}
+    BEGIN_WITH_STACK_HEAP(PORT_REPLY_SIZE + TUPLE_SIZE(2) + TERM_BINARY_HEAP_SIZE(6), heap);
+    {
+        term mac_term = term_from_literal_binary(mac, 6, &heap, driver_data->global);
+        term reply = port_heap_create_tuple2(&heap, atom, mac_term);
+        send_term(&heap, reply);
+    }
+    END_WITH_STACK_HEAP(heap, driver_data->global);
+}
+
+static void send_ap_sta_connected(uint8_t *mac)
+{
+    send_atom_mac(globalcontext_make_atom(driver_data->global, ap_sta_connected_atom), mac);
+}
+
+static void send_ap_sta_disconnected(uint8_t *mac)
+{
+    send_atom_mac(globalcontext_make_atom(driver_data->global, ap_sta_disconnected_atom), mac);
+}
+
 static term start_sta(term sta_config, GlobalContext *global)
 {
     term ssid_term = interop_kv_get_value(sta_config, ssid_atom, global);
@@ -171,32 +209,124 @@ static term start_sta(term sta_config, GlobalContext *global)
     return OK_ATOM;
 }
 
-static term start_ap(term ap_config, GlobalContext *glb)
+static char *get_default_device_name()
 {
-    UNUSED(ap_config);
-    UNUSED(glb);
-    return BADARG_ATOM;
+    uint8_t mac[6];
+    int err = cyw43_wifi_get_mac(&cyw43_state, CYW43_ITF_STA, mac);
+    if (err) {
+        return NULL;
+    }
+
+    size_t buf_size = strlen("atomvm-") + 12 + 1;
+    char *buf = malloc(buf_size);
+    if (IS_NULL_PTR(buf)) {
+        return NULL;
+    }
+    snprintf(buf, buf_size,
+        "atomvm-%02x%02x%02x%02x%02x%02x", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+    return buf;
 }
 
-static void network_driver_netif_status_cb(struct netif *netif)
+static void network_driver_cyw43_assoc_cb(bool assoc)
 {
-    if (netif == &cyw43_state.netif[CYW43_ITF_STA]) {
-        // We don't really need to lock to call cyw43_tcpip_link_status
-        // However, we take advantage of this lock to protect driver_data->link_status.
-        cyw43_arch_lwip_begin();
-        int link_status = cyw43_tcpip_link_status(&cyw43_state, CYW43_ITF_STA);
-        int previous_link_status = driver_data->link_status;
-        driver_data->link_status = link_status;
-        cyw43_arch_lwip_end();
-        if (link_status != previous_link_status) {
-            if (link_status == CYW43_LINK_DOWN) {
-                send_sta_disconnected();
-            } else if (link_status == CYW43_LINK_JOIN) {
-                send_sta_connected();
-            } else if (link_status == CYW43_LINK_UP) {
-                send_got_ip(netif);
+    UNUSED(assoc);
+
+    int max_stas;
+    cyw43_wifi_ap_get_max_stas(&cyw43_state, &max_stas);
+    uint8_t *new_macs = malloc(6 * max_stas);
+    int nb_stas;
+    cyw43_wifi_ap_get_stas(&cyw43_state, &nb_stas, new_macs);
+    // Determine new macs.
+    for (int i = 0; i < nb_stas; i++) {
+        bool new_mac = true;
+        for (int j = 0; j < driver_data->stas_count; j++) {
+            if (memcmp(&driver_data->stas_mac[6 * j], &new_macs[6 * i], 6) == 0) {
+                new_mac = false;
+                break;
             }
         }
+        if (new_mac) {
+            send_ap_sta_connected(&new_macs[6 * i]);
+        }
+    }
+    // Determine old macs
+    for (int j = 0; j < driver_data->stas_count; j++) {
+        bool old_mac = true;
+        for (int i = 0; i < nb_stas; i++) {
+            if (memcmp(&driver_data->stas_mac[6 * j], &new_macs[6 * i], 6) == 0) {
+                old_mac = false;
+                break;
+            }
+        }
+        if (old_mac) {
+            send_ap_sta_disconnected(&driver_data->stas_mac[6 * j]);
+        }
+    }
+    free(driver_data->stas_mac);
+    new_macs = realloc(new_macs, 6 * nb_stas);
+    driver_data->stas_mac = new_macs;
+    driver_data->stas_count = nb_stas;
+}
+
+static term start_ap(term ap_config, GlobalContext *global)
+{
+    term ssid_term = interop_kv_get_value(ap_config, ssid_atom, global);
+    term pass_term = interop_kv_get_value(ap_config, psk_atom, global);
+
+    //
+    // Check parameters
+    //
+    char *ssid = NULL;
+    if (term_is_invalid_term(ssid_term)) {
+        ssid = get_default_device_name();
+    } else {
+        int ok = 0;
+        ssid = interop_term_to_string(ssid_term, &ok);
+        if (!ok || IS_NULL_PTR(ssid)) {
+            return BADARG_ATOM;
+        }
+    }
+    char *psk = NULL;
+    if (!term_is_invalid_term(pass_term)) {
+        int ok = 0;
+        psk = interop_term_to_string(pass_term, &ok);
+        if (strlen(psk) < 8) {
+            free(ssid);
+            return BADARG_ATOM;
+        }
+        if (!ok) {
+            free(ssid);
+            return BADARG_ATOM;
+        }
+    }
+
+    uint32_t auth = (psk == NULL) ? CYW43_AUTH_OPEN : CYW43_AUTH_WPA2_AES_PSK;
+    cyw43_state.assoc_cb = network_driver_cyw43_assoc_cb;
+    cyw43_arch_enable_ap_mode(ssid, psk, auth);
+    send_ap_started();
+    free(ssid);
+    free(psk);
+
+    return OK_ATOM;
+}
+
+static void network_driver_netif_status_cb(struct netif *netif)
+{
+    // We don't really need to lock to call cyw43_tcpip_link_status
+    // However, we take advantage of this lock to protect driver_data->link_status.
+    cyw43_arch_lwip_begin();
+    int link_status = cyw43_tcpip_link_status(&cyw43_state, CYW43_ITF_STA);
+    int previous_link_status = driver_data->link_status;
+    driver_data->link_status = link_status;
+    cyw43_arch_lwip_end();
+    if (link_status != previous_link_status) {
+        if (link_status == CYW43_LINK_DOWN) {
+            send_sta_disconnected();
+        } else if (link_status == CYW43_LINK_JOIN) {
+            send_sta_connected();
+        } else if (link_status == CYW43_LINK_UP) {
+            send_got_ip(netif);
+        }
     }
 }
 
@@ -210,11 +340,15 @@ static void start_network(Context *ctx, term pid, term ref, term config)
 
     if (driver_data == NULL) {
         driver_data = malloc(sizeof(struct NetworkDriverData));
+        driver_data->stas_mac = NULL;
     }
     driver_data->global = ctx->global;
     driver_data->owner_process_id = term_to_local_process_id(pid);
     driver_data->ref_ticks = term_to_ref_ticks(ref);
     driver_data->link_status = CYW43_LINK_DOWN;
+    free(driver_data->stas_mac);
+    driver_data->stas_count = 0;
+    driver_data->stas_mac = NULL;
 
     //
     // Get the STA and AP config, if set
@@ -317,6 +451,9 @@ void network_driver_destroy(GlobalContext *global)
 {
     UNUSED(global);
 
+    if (driver_data) {
+        free(driver_data->stas_mac);
+    }
     free(driver_data);
     driver_data = NULL;
 }