Add L2 PPP and PPPoE

src/drivers/at_cmd.c

@@ -0,0 +1,153 @@
+#include "net_builtin.h"
+
+#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_ATCMD) && MG_ENABLE_DRIVER_ATCMD
+
+#define MG_HDLC_FLAG 0x7e  // HDLC frame delimiter
+#define MG_HDLC_ESC 0x7d   // HDLC escape byte for byte stuffing
+
+#define MG_ATCMD_AT_TIMEOUT 2000
+
+static size_t print_atcmd(void (*out)(char, void *), void *arg, va_list *ap) {
+  struct mg_str s = va_arg(*ap, struct mg_str);
+  for (size_t i = 0; i < s.len; i++) out(s.buf[i] < 0x20 ? '.' : s.buf[i], arg);
+  return s.len;
+}
+
+static void mg_atcmd_reset(struct mg_tcpip_driver_atcmd_data *dd) {
+  dd->script_index = 0;
+  dd->deadline = 0;
+  if (dd->reset) dd->reset(dd->usart);
+}
+
+static bool mg_atcmd_handle(struct mg_tcpip_if *ifp) {
+  struct mg_tcpip_driver_atcmd_data *dd = (struct mg_tcpip_driver_atcmd_data *) ifp->driver_data;
+  if (dd->script == NULL || dd->script_index < 0) return true;
+  if (dd->deadline == 0) dd->deadline = mg_millis() + MG_ATCMD_AT_TIMEOUT;
+  for (;;) {
+    if (dd->script_index % 2 == 0) {  // send AT command
+      const char *cmd = dd->script[dd->script_index];
+      MG_DEBUG(("send AT[%d]: %M", dd->script_index, print_atcmd, mg_str(cmd)));
+      while (*cmd) dd->tx(dd->usart, *cmd++);
+      dd->script_index++;
+      ifp->recv_queue.head = 0;
+    } else {  // check AT command response
+      const char *expect = dd->script[dd->script_index];
+      struct mg_queue *q = &ifp->recv_queue;
+      for (;;) {
+        int c;
+        bool is_timeout = dd->deadline > 0 && mg_millis() > dd->deadline;
+        bool is_overflow = q->head >= q->size - 1;
+        if (is_timeout || is_overflow) {
+          MG_ERROR(("AT error: %s, retrying...", is_timeout ? "timeout" : "overflow"));
+          mg_atcmd_reset(dd);
+          return false;  // FAIL
+        }
+        if ((c = dd->rx(dd->usart)) < 0) return false;  // no data
+        q->buf[q->head++] = c;
+        if (mg_match(mg_str_n(q->buf, q->head), mg_str(expect), NULL)) {
+          MG_DEBUG(("recv AT[%d]: %M", dd->script_index, print_atcmd,
+                    mg_str_n(q->buf, q->head)));
+          dd->script_index++;
+          q->head = 0;
+          break;
+        }
+      }
+    }
+    if (dd->script[dd->script_index] == NULL) {
+      MG_DEBUG(("finished AT script"));
+      dd->script_index = -1;
+      return true;
+    }
+  }
+}
+
+static void byte_stuff(struct mg_tcpip_driver_atcmd_data *dd, uint8_t b);
+static bool byte_unstuff(struct mg_tcpip_driver_atcmd_data *dd, uint8_t *p);
+
+static size_t mg_atcmd_rx(void *buf, size_t len, struct mg_tcpip_if *ifp) {
+  struct mg_tcpip_driver_atcmd_data *dd = (struct mg_tcpip_driver_atcmd_data *) ifp->driver_data;
+  struct mg_queue *q = &ifp->recv_queue;
+  
+  if (!dd->link) return 0;
+
+  while (q->head < q->size) { // read as many bytes as possible
+    uint8_t b;
+    int c = dd->rx(dd->usart);
+    if (c < 0) return 0;      // no more bytes, exit
+    b = (uint8_t) c;
+    if (b == MG_HDLC_FLAG) {
+      if (q->head == 0) { // first flag: skip
+        dd->unstuffing = false;
+        continue;
+      } else { // last flag: end of frame, exit loop
+        break;
+      }
+    }
+    if (!dd->no_byte_stuff && !byte_unstuff(dd, &b)) continue;
+    q->buf[q->head++] = b;
+  }
+  len = (q->head <= len) ? q->head : 0;
+  memmove(buf, q->buf, len);
+  q->head = 0;
+  return len;
+}
+
+static size_t mg_atcmd_tx(const void *buf, size_t len, struct mg_tcpip_if *ifp) {
+  struct mg_tcpip_driver_atcmd_data *dd = (struct mg_tcpip_driver_atcmd_data *) ifp->driver_data;
+  uint8_t *p = (uint8_t *) buf;
+  size_t n = len;
+
+  if (!dd->link) return 0;
+
+  dd->tx(dd->usart, MG_HDLC_FLAG);
+  while (n--) {
+    if (dd->no_byte_stuff) {
+      dd->tx(dd->usart, *p++);
+    } else {
+      byte_stuff(dd, *p++);
+    }
+  }
+  dd->tx(dd->usart, MG_HDLC_FLAG);
+  return len;
+}
+
+static bool mg_atcmd_init(struct mg_tcpip_if *ifp) {
+  ifp->recv_queue.size = 1506;  // PPP MTU=1500 + header + HDLC w/ no flags
+  return true;
+}
+
+static bool mg_atcmd_poll(struct mg_tcpip_if *ifp, bool s1) {
+  struct mg_tcpip_driver_atcmd_data *dd = (struct mg_tcpip_driver_atcmd_data *) ifp->driver_data;
+  dd->link = mg_atcmd_handle(ifp);
+  return s1 ? dd->link :false;
+}
+
+
+struct mg_tcpip_driver mg_tcpip_driver_atcmd = {mg_atcmd_init, mg_atcmd_tx, mg_atcmd_rx, mg_atcmd_poll};
+
+
+
+static void byte_stuff(struct mg_tcpip_driver_atcmd_data *dd, uint8_t b) {
+  if ((b < 0x20) || (b == MG_HDLC_ESC) || (b == MG_HDLC_FLAG)) {
+    dd->tx(dd->usart, MG_HDLC_ESC);
+    dd->tx(dd->usart, b ^ 0x20);
+  } else {
+    dd->tx(dd->usart, b);
+  }
+}
+
+static bool byte_unstuff(struct mg_tcpip_driver_atcmd_data *dd, uint8_t *p) {
+  if (!dd->unstuffing) {
+    if (*p == MG_HDLC_ESC) {
+      dd->unstuffing = true;
+      return false;
+    } else {
+      return true;
+    }
+  }
+  dd->unstuffing = false;
+  *p ^= 0x20;
+  return true;
+}
+
+#endif