Make sure NWP is stopped before sl_Start

In SDK 1.2.0 TI decided to stop resetting NWP before sl_Start, which in
practice means that sl_start will hang on subsequent runs after the first.

See this post for details and suggested solution:

https://e2e.ti.com/support/wireless_connectivity/simplelink_wifi_cc31xx_cc32xx/f/968/p/499123/1806610#1806610

However, since they don't provide OS_debug variant of simplelink.a and
adding another project dependency will complicate our demo even more,
we just take the required bit of code.

PUBLISHED_FROM=c729c0fcbb240aa90a716edd43888de5881d6731

examples/CC3200/ccs/MG_hello/main.c

@@ -42,7 +42,8 @@
 
 #include "wifi.h"
 
-static const char *upload_form = "\
+static const char *upload_form =
+    "\
 <h1>Upload file</h1> \
 <form action='/upload' method='POST' enctype='multipart/form-data'> \
   <input type='file' name='file'> \
@@ -80,8 +81,7 @@ void mg_ev_handler(struct mg_connection *nc, int ev, void *ev_data) {
           ("HTTP request from %s: %.*s %.*s", addr, (int) hm->method.len,
            hm->method.p, (int) hm->uri.len, hm->uri.p));
       if (mg_vcmp(&hm->uri, "/upload") == 0 ||
-          (mg_vcmp(&hm->uri, "/") == 0 &&
-           mg_stat("SL:index.html", &st) != 0)) {
+          (mg_vcmp(&hm->uri, "/") == 0 && mg_stat("SL:index.html", &st) != 0)) {
         mg_send(nc, upload_form, strlen(upload_form));
         nc->flags |= MG_F_SEND_AND_CLOSE;
         break;
@@ -114,7 +114,14 @@ void mg_ev_handler(struct mg_connection *nc, int ev, void *ev_data) {
 static void mg_init(struct mg_mgr *mgr) {
   LOG(LL_INFO, ("MG task running"));
 
-  sl_Start(0, 0, 0);
+  stop_nwp(); /* See function description in wifi.c */
+  int role = sl_Start(0, 0, 0);
+  if (role < 0) {
+    LOG(LL_ERROR, ("Failed to start NWP"));
+    return;
+  }
+
+  LOG(LL_INFO, ("NWP started"));
 
   sl_fs_init();
 

examples/CC3200/main.c

@@ -50,7 +50,8 @@
 #define BM222_ADDR 0x18
 #define TMP006_ADDR 0x41
 
-static const char *upload_form = "\
+static const char *upload_form =
+    "\
 <h1>Upload file</h1> \
 <form action='/upload' method='POST' enctype='multipart/form-data'> \
   <input type='file' name='file'> \
@@ -88,8 +89,7 @@ static void mg_ev_handler(struct mg_connection *nc, int ev, void *ev_data) {
           ("HTTP request from %s: %.*s %.*s", addr, (int) hm->method.len,
            hm->method.p, (int) hm->uri.len, hm->uri.p));
       if (mg_vcmp(&hm->uri, "/upload") == 0 ||
-          (mg_vcmp(&hm->uri, "/") == 0 &&
-           mg_stat("SL:index.html", &st) != 0)) {
+          (mg_vcmp(&hm->uri, "/") == 0 && mg_stat("SL:index.html", &st) != 0)) {
         mg_send(nc, upload_form, strlen(upload_form));
         nc->flags |= MG_F_SEND_AND_CLOSE;
         break;
@@ -131,14 +131,20 @@ static void mg_ev_handler(struct mg_connection *nc, int ev, void *ev_data) {
 
 static void mg_init(struct mg_mgr *mgr) {
   LOG(LL_INFO, ("MG task running"));
+
+  stop_nwp(); /* See function description in wifi.c */
+  int role = sl_Start(0, 0, 0);
+  if (role < 0) {
+    LOG(LL_ERROR, ("Failed to start NWP"));
+    return;
+  }
+  LOG(LL_INFO, ("NWP started"));
   GPIO_IF_LedToggle(MCU_RED_LED_GPIO);
 
   data_init_sensors(TMP006_ADDR, BM222_ADDR);
 
   sl_fs_init();
 
-  sl_Start(NULL, NULL, NULL);
-
 #if defined(WIFI_STA_SSID)
   if (!wifi_setup_sta(WIFI_STA_SSID, WIFI_STA_PASS)) {
     LOG(LL_ERROR, ("Error setting up WiFi station"));

examples/CC3200/wifi.c

@@ -2,11 +2,14 @@
 
 #include "mongoose.h"
 
+#include <simplelink/cc_pal.h>
 #include <simplelink/include/wlan.h>
 
 #include <inc/hw_types.h>
 
 #include <driverlib/gpio.h>
+#include <driverlib/utils.h>
+
 #include <example/common/gpio_if.h>
 
 void SimpleLinkWlanEventHandler(SlWlanEvent_t *e) {
@@ -113,3 +116,50 @@ bool wifi_setup_sta(const char *ssid, const char *pass) {
   }
   return true;
 }
+
+/*
+ * In SDK 1.2.0 TI decided to stop resetting NWP before sl_Start, which in
+ * practice means that sl_start will hang on subsequent runs after the first.
+ *
+ * See this post for details and suggested solution:
+ * https://e2e.ti.com/support/wireless_connectivity/simplelink_wifi_cc31xx_cc32xx/f/968/p/499123/1806610#1806610
+ *
+ * However, since they don't provide OS_debug variant of simplelink.a and
+ * adding another project dependency will complicate our demo even more,
+ * we just take the required bit of code.
+ *
+ * This is a copy-paste of NwpPowerOnPreamble from cc_pal.c.
+ */
+void stop_nwp(void) {
+#define MAX_RETRY_COUNT 1000
+  unsigned int sl_stop_ind, apps_int_sts_raw, nwp_lpds_wake_cfg;
+  unsigned int retry_count;
+  /* Perform the sl_stop equivalent to ensure network services
+     are turned off if active */
+  HWREG(0x400F70B8) = 1; /* APPs to NWP interrupt */
+  UtilsDelay(800000 / 5);
+
+  retry_count = 0;
+  nwp_lpds_wake_cfg = HWREG(0x4402D404);
+  sl_stop_ind = HWREG(0x4402E16C);
+
+  if ((nwp_lpds_wake_cfg != 0x20) && /* Check for NWP POR condition */
+      !(sl_stop_ind & 0x2))          /* Check if sl_stop was executed */
+  {
+    /* Loop until APPs->NWP interrupt is cleared or timeout */
+    while (retry_count < MAX_RETRY_COUNT) {
+      apps_int_sts_raw = HWREG(0x400F70C0);
+      if (apps_int_sts_raw & 0x1) {
+        UtilsDelay(800000 / 5);
+        retry_count++;
+      } else {
+        break;
+      }
+    }
+  }
+  HWREG(0x400F70B0) = 1; /* Clear APPs to NWP interrupt */
+  UtilsDelay(800000 / 5);
+
+  /* Stop the networking services */
+  NwpPowerOff();
+}

examples/CC3200/wifi.h

@@ -10,5 +10,6 @@
 
 bool wifi_setup_ap(const char *ssid, const char *pass, int channel);
 bool wifi_setup_sta(const char *ssid, const char *pass);
+void stop_nwp();
 
 #endif /* CS_MONGOOSE_EXAMPLES_CC3200_WIFI_H_ */