Import of the watch repository from Pebble

src/fw/console/pulse_llc.c

@@ -0,0 +1,147 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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.
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+#include "console/pulse_llc.h"
+#include "console/pulse_protocol_impl.h"
+
+#include "console/pulse_internal.h"
+#include "util/attributes.h"
+#include "util/math.h"
+
+#define LLC_INMSG_LINK_ESTABLISHMENT_REQUEST (1)
+#define LLC_INMSG_LINK_CLOSE_REQUEST (3)
+#define LLC_INMSG_ECHO_REQUEST (5)
+#define LLC_INMSG_CHANGE_BAUD (7)
+
+#define LLC_OUTMSG_LINK_OPENED (2)
+#define LLC_OUTMSG_LINK_CLOSED (4)
+#define LLC_OUTMSG_ECHO_REPLY (6)
+#define LLC_OUTMSG_INVALID_LLC_MESSAGE (128)
+#define LLC_OUTMSG_UNKNOWN_PROTOCOL_NUMBER (129)
+
+
+static void prv_bad_packet_response(uint8_t type, uint8_t bad_id, void *body,
+                                    size_t body_length);
+static void prv_handle_change_baud(void *body, size_t body_length);
+
+
+void pulse_llc_handler(void *packet, size_t length) {
+  if (!length) {
+    // Message too small; doesn't contain a type field.
+    uint8_t *message = pulse_best_effort_send_begin(PULSE_PROTOCOL_LLC);
+    *message = LLC_OUTMSG_INVALID_LLC_MESSAGE;
+    pulse_best_effort_send(message, sizeof(uint8_t));
+    return;
+  }
+
+  uint8_t type = *(uint8_t*)packet;
+  switch (type) {
+    case LLC_INMSG_LINK_ESTABLISHMENT_REQUEST:
+      pulse_llc_send_link_opened_msg();
+      return;
+    case LLC_INMSG_LINK_CLOSE_REQUEST:
+      pulse_end();
+      return;
+    case LLC_INMSG_ECHO_REQUEST:
+      *(uint8_t*)packet = LLC_OUTMSG_ECHO_REPLY;
+
+      uint8_t *message = pulse_best_effort_send_begin(PULSE_PROTOCOL_LLC);
+      memcpy(message, packet, length);
+
+      pulse_best_effort_send(message, length);
+      return;
+    case LLC_INMSG_CHANGE_BAUD:
+      prv_handle_change_baud((char*)packet + 1, length - 1);
+      return;
+    default:
+      prv_bad_packet_response(LLC_OUTMSG_INVALID_LLC_MESSAGE, type,
+                              (char*)packet + 1, length - 1);
+      return;
+  }
+}
+
+void pulse_llc_link_state_handler(PulseLinkState link_state) {
+}
+
+void pulse_llc_send_link_opened_msg(void) {
+  typedef struct PACKED Response {
+    uint8_t type;
+    uint8_t pulse_version;
+    uint16_t mtu;
+    uint16_t mru;
+    uint8_t timeout;
+  } Response;
+
+  Response *response = pulse_best_effort_send_begin(PULSE_PROTOCOL_LLC);
+  *response = (Response) {
+    .type = LLC_OUTMSG_LINK_OPENED,
+    .pulse_version = 1,
+    .mtu = PULSE_MAX_SEND_SIZE + PULSE_MIN_FRAME_LENGTH,
+    .mru = PULSE_MAX_RECEIVE_UNIT,
+    .timeout = PULSE_KEEPALIVE_TIMEOUT_DECISECONDS
+  };
+
+  pulse_best_effort_send(response, sizeof(Response));
+}
+
+void pulse_llc_send_link_closed_msg(void) {
+  uint8_t *link_close_response = pulse_best_effort_send_begin(
+      PULSE_PROTOCOL_LLC);
+  *link_close_response = LLC_OUTMSG_LINK_CLOSED;
+
+  pulse_best_effort_send(link_close_response, sizeof(uint8_t));
+}
+
+static void prv_bad_packet_response(uint8_t type, uint8_t bad_id, void *body,
+                                    size_t body_length) {
+  typedef struct PACKED Response {
+    uint8_t type;
+    uint8_t bad_identifier;
+    char body[8];
+  } Response;
+
+  Response *response = pulse_best_effort_send_begin(PULSE_PROTOCOL_LLC);
+  *response = (Response) {
+    .type = type,
+    .bad_identifier = bad_id
+  };
+
+  body_length = MIN(sizeof(response->body), body_length);
+  if (body_length) {
+    memcpy(response->body, body, body_length);
+  }
+
+  pulse_best_effort_send(response, 2 + body_length);
+}
+
+void pulse_llc_unknown_protocol_handler(uint8_t protocol, void *packet,
+                                        size_t length) {
+  prv_bad_packet_response(LLC_OUTMSG_UNKNOWN_PROTOCOL_NUMBER, protocol, packet,
+                          length);
+}
+
+void prv_handle_change_baud(void *body, size_t body_length) {
+  if (body_length != sizeof(uint32_t)) {
+    // Don't send a response; the client will have already changed its receiver
+    // baud rate.
+    return;
+  }
+  uint32_t *new_baud = body;
+  pulse_change_baud_rate(*new_baud);
+}