stm32: Integrate lwIP as implementation of usocket module.

This patch allows to use lwIP as the implementation of the usocket module,
instead of the existing socket-multiplexer that delegates the entire TCP/IP
layer to the NIC itself.

This is disabled by default, and enabled by defining MICROPY_PY_LWIP to 1.

When enabled, the lwIP TCP/IP stack will be included in the build with
default settings for memory usage and performance (see
lwip_inc/lwipopts.h).  It is then up to a particular NIC to register itself
with lwIP using the standard lwIP netif API.

1 files changed, 10 insertions, 0 deletions

diff --git a/ports/stm32/main.c b/ports/stm32/main.c
index 460a19ccb..44f5b05c4 100644
--- a/ports/stm32/main.c
+++ b/ports/stm32/main.c
@@ -34,6 +34,7 @@
 #include "lib/mp-readline/readline.h"
 #include "lib/utils/pyexec.h"
 #include "lib/oofatfs/ff.h"
+#include "lwip/init.h"
 #include "extmod/vfs.h"
 #include "extmod/vfs_fat.h"
 
@@ -512,6 +513,12 @@ void stm32_main(uint32_t reset_mode) {
     sdcard_init();
     #endif
     storage_init();
+    #if MICROPY_PY_LWIP
+    // lwIP doesn't allow to reinitialise itself by subsequent calls to this function
+    // because the system timeout list (next_timeout) is only ever reset by BSS clearing.
+    // So for now we only init the lwIP stack once on power-up.
+    lwip_init();
+    #endif
 
 soft_reset:
 
@@ -726,6 +733,9 @@ soft_reset_exit:
     storage_flush();
 
     printf("PYB: soft reboot\n");
+    #if MICROPY_PY_NETWORK
+    mod_network_deinit();
+    #endif
     timer_deinit();
     uart_deinit();
 #if MICROPY_HW_ENABLE_CAN