[nrf fromtree] bluetooth: host: Allow for ECDH operations through system workq

Change allows performing ECDH operations through system workq. This is
done to allow reducing memory consumption by disabling the long workq on
small SoCs.

Signed-off-by: Marek Pieta <[email protected]>
(cherry picked from commit c7f3ad6)

Author: MarekPieta

subsys/bluetooth/host/Kconfig

@@ -1002,10 +1002,11 @@ config BT_ECC
 	select PSA_WANT_KEY_TYPE_ECC_KEY_PAIR_EXPORT
 	select PSA_WANT_ECC_SECP_R1_256
 	imply MBEDTLS_PSA_P256M_DRIVER_ENABLED if MBEDTLS_PSA_CRYPTO_C
-	select BT_LONG_WQ
+	imply BT_LONG_WQ
 	help
-	  If this option is set, internal APIs will be available to perform ECDH operations
-	  through the long work queue. operations needed e.g. by LE Secure Connections.
+	  If this option is set, internal APIs will be available to perform ECDH operations through
+	  the long work queue (or system work queue). The operations are used e.g. by LE Secure
+	  Connections.
 
 endif # BT_HCI_HOST
 

subsys/bluetooth/host/ecc.c

@@ -279,7 +279,11 @@ int bt_pub_key_gen(struct bt_pub_key_cb *new_cb)
 
 	atomic_clear_bit(bt_dev.flags, BT_DEV_HAS_PUB_KEY);
 
-	bt_long_wq_submit(&pub_key_work);
+	if (IS_ENABLED(CONFIG_BT_LONG_WQ)) {
+		bt_long_wq_submit(&pub_key_work);
+	} else {
+		k_work_submit(&pub_key_work);
+	}
 
 	return 0;
 }
@@ -338,7 +342,11 @@ int bt_dh_key_gen(const uint8_t remote_pk[BT_PUB_KEY_LEN], bt_dh_key_cb_t cb)
 	sys_memcpy_swap(&ecc.public_key_be[BT_PUB_KEY_COORD_LEN],
 			&remote_pk[BT_PUB_KEY_COORD_LEN], BT_PUB_KEY_COORD_LEN);
 
-	bt_long_wq_submit(&dh_key_work);
+	if (IS_ENABLED(CONFIG_BT_LONG_WQ)) {
+		bt_long_wq_submit(&dh_key_work);
+	} else {
+		k_work_submit(&dh_key_work);
+	}
 
 	return 0;
 }