skald_bthome_saul: add capability for custom SAUL entries

examples/skald_bthome/main.c

@@ -78,10 +78,20 @@ int _get_encryption_key(void)
 }
 #endif
 
+static int _add_text(skald_bthome_ctx_t *ctx, uint8_t obj_id, phydat_t *data, uint8_t idx)
+{
+    static const char info[] = "RIOT";
+
+    (void)data;
+    (void)idx;
+    return skald_bthome_add_measurement(ctx, obj_id, info, strlen(info));
+}
+
 int main(void)
 {
     saul_reg_t *dev = saul_reg;
     unsigned i = 0;
+    int res;
 
     ztimer_sleep(ZTIMER_MSEC, 2000);
     printf("Skald and the tale of Harald's home\n");
@@ -112,7 +122,6 @@ int main(void)
         return 1;
     }
     while (dev && (i < CONFIG_BTHOME_SAUL_REG_DEVS)) {
-        int res;
         _saul_devs[i].saul = *dev;  /* copy registry entry */
         _saul_devs[i].saul.next = NULL;
         printf("Adding %s (%s) to BTHome.\n", dev->name, saul_class_to_str(dev->driver->type));
@@ -126,6 +135,17 @@ int main(void)
         dev = dev->next;
     }
     assert(!saul_reg || _ctx.devs);
+    if (i < CONFIG_BTHOME_SAUL_REG_DEVS) {
+        memset(&_saul_devs[i].saul, 0, sizeof(_saul_devs[i].saul));
+        _saul_devs[i].obj_id = BTHOME_ID_TEXT;
+        _saul_devs[i].flags = SKALD_BTHOME_SAUL_FLAGS_CUSTOM;
+        _saul_devs[i].add_measurement = _add_text;
+        if ((res = skald_bthome_saul_add(&_ctx, &_saul_devs[i])) < 0) {
+            errno = -res;
+            perror("Unable to add text info to BTHome");
+        };
+        i++;
+    }
     skald_bthome_advertise(&_ctx, BTHOME_ADV_INTERVAL);
     return 0;
 }

sys/Makefile.dep

@@ -592,6 +592,11 @@ ifneq (,$(filter skald_bthome_saul,$(USEMODULE)))
   USEMODULE += saul_reg
 endif
 
+ifneq (,$(filter skald_update_pkt_cb,$(USEMODULE)))
+  USEMODULE += event
+  USEMODULE += skald
+endif
+
 ifneq (,$(filter bluetil_addr,$(USEMODULE)))
   USEMODULE += fmt
 endif

sys/include/net/skald/bthome.h

@@ -60,6 +60,16 @@ extern "C" {
 typedef struct skald_bthome_ctx skald_bthome_ctx_t;
 
 #if IS_USED(MODULE_SKALD_BTHOME_SAUL) || defined(DOXYGEN)
+/**
+ * @brief   Flags for the BTHome-SAUL-adapter
+ */
+typedef enum {
+    /**
+     * @brief   Use custom object ID and add-measurement callback
+     */
+    SKALD_BTHOME_SAUL_FLAGS_CUSTOM = 0x01,
+} skald_bthome_saul_flags_t;
+
 /**
  * @brief   BTHome-SAUL-adapter
  */
@@ -76,9 +86,20 @@ typedef struct {
      *
      * @see skald_bthome_id_t
      *
-     * Will be filled by @ref skald_bthome_saul_add().
+     * Will be filled by @ref skald_bthome_saul_add() if
+     * @ref SKALD_BTHOME_SAUL_FLAGS_CUSTOM is unset in
+     * skald_bthome_saul_t::flags. Otherwise, set to the desired
+     * object ID for the measurement.
      */
     skald_bthome_id_t obj_id;
+    /**
+     * @brief   Flags for the BTHome-SAUL-adapter
+     *
+     * @see skald_bthome_saul_flags_t
+     *
+     * May be set before calling @ref skald_bthome_saul_add()
+     */
+    skald_bthome_saul_flags_t flags;
 
     /**
      * @brief   Callback to add measurement from SAUL registry entry
@@ -87,7 +108,10 @@ typedef struct {
      * @ref saul_reg_read() and should ultimately call
      * @ref skald_bthome_add_measurement() * (or one of its wrappers).
      *
-     * Will be filled by @ref skald_bthome_saul_add().
+     * Will be filled by @ref skald_bthome_saul_add() if
+     * @ref SKALD_BTHOME_SAUL_FLAGS_CUSTOM is unset in
+     * skald_bthome_saul_t::flags. Otherwise, set to the desired
+     * object ID for the measurement.
      *
      * @param[in,out] ctx   BTHome advertising context. MUST not be NULL.
      * @param[in] obj_id    The object ID for the measurement.

sys/net/ble/skald/skald_bthome_saul.c

@@ -427,12 +427,14 @@ static void _update_saul_measurements(skald_ctx_t *skald_ctx)
     _reset_hdr(ctx);
     skald_bthome_saul_t *ptr = ctx->devs;
     while (ptr) {
-        int dim;
+        int dim = 1;
-        phydat_t data;
+        phydat_t data = { 0 };
 
-        dim = saul_reg_read(&ptr->saul, &data);
+        if (ptr->saul.driver) {
-        if (dim <= 0) {
+            dim = saul_reg_read(&ptr->saul, &data);
-            continue;
+            if (dim <= 0) {
+                continue;
+            }
         }
         for (uint8_t i = 0; i < dim; i++) {
             if (ptr->add_measurement(ctx, ptr->obj_id, &data, i) < 0) {
@@ -451,22 +453,24 @@ static void _update_saul_measurements(skald_ctx_t *skald_ctx)
 
 int skald_bthome_saul_add(skald_bthome_ctx_t *ctx, skald_bthome_saul_t *saul)
 {
-    int dim;
+    if ((saul->saul.driver != NULL) &&
-    phydat_t sample;
+        (saul->saul.driver->type & SAUL_CAT_MASK) != SAUL_CAT_SENSE) {
-
-    if ((saul->saul.driver->type & SAUL_CAT_MASK) != SAUL_CAT_SENSE) {
         return -ENOTSUP;
     }
 
     if (!ctx->skald.update_pkt) {
         ctx->skald.update_pkt = &_update_saul_measurements;
     }
-    dim = saul_reg_read(&saul->saul, &sample);
+    if (!(saul->flags & SKALD_BTHOME_SAUL_FLAGS_CUSTOM)) {
-    if (dim <= 0) {
+        phydat_t sample;
-        return -ENODEV;
+        int dim = saul_reg_read(&saul->saul, &sample);
-    }
+
-    if (_saul_sense_to_bthome_id(saul, &sample) < 0) {
+        if (dim <= 0) {
-        return -ENOENT;
+            return -ENODEV;
+        }
+        if (_saul_sense_to_bthome_id(saul, &sample) < 0) {
+            return -ENOENT;
+        }
     }
     if (ctx->devs) {
         skald_bthome_saul_t *ptr = ctx->devs;