lpac: add uqmi backend

This adds an additional OpenWrt specific backend to use lpac with the
uqmi tooling used by OpenWrt to manage QMI based modems.

This allows lpac to manage eUICC chips without the need for other,
potentially bigger, software using the installed modem.

Also set this backend as the new default, as users probably expect being
able to download profiles using their cellular modem.

Profile-Switching
-----------------
With some eUICC modem combinations you might require to powercycle the
UIM slot using uqmi after changing the active profile. To do this,
simply execute

$ uqmi -d /dev/cdc-wdm0 --uim-power-off --uim-slot=1
$ uqmi -d /dev/cdc-wdm0 --uim-power-on --uim-slot=1

Note
----
SM-DP+ might use encryption parameters which are incompatible with
mbedtls which cURL is by default compiled for.

This was observed when attempting to download a profile from
Vodafone DE.

If you encounter issues in that regard, try to install a version of
libcurl which is compiled with OpenSSL support.

Signed-off-by: David Bauer <[email protected]>

utils/lpac/Config.in

@@ -13,4 +13,10 @@ config LPAC_WITH_AT
 	help
 	  Compile LPAC with APDU AT Backend support.
 
+config LPAC_WITH_UQMI
+	bool "Include APDU uqmi Backend support"
+	default y
+	help
+	  Compile LPAC with APDU uqmi Backend support.
+
 endmenu

utils/lpac/Makefile

@@ -49,6 +49,7 @@ TARGET_CFLAGS += $(FPIC)
 CMAKE_OPTIONS += \
   -DLPAC_WITH_APDU_PCSC=$(if $(CONFIG_LPAC_WITH_PCSC),ON,OFF) \
   -DLPAC_WITH_APDU_AT=$(if $(CONFIG_LPAC_WITH_AT),ON,OFF) \
+  -DLPAC_WITH_APDU_UQMI=$(if $(CONFIG_LPAC_WITH_UQMI),ON,OFF) \
   -DLPAC_WITH_APDU_QMI_QRTR=OFF
 
 define Package/lpac/install

utils/lpac/files/lpac.sh

@@ -2,15 +2,12 @@
 
 . /lib/config/uci.sh
 
-APDU_BACKEND="$(uci_get lpac global apdu_backend at)"
+APDU_BACKEND="$(uci_get lpac global apdu_backend uqmi)"
 APDU_DEBUG="$(uci_get lpac global apdu_debug 0)"
 
 HTTP_BACKEND="$(uci_get lpac global http_backend curl)"
 HTTP_DEBUG="$(uci_get lpac global http_debug 0)"
 
-AT_DEVICE="$(uci_get lpac at device /dev/ttyUSB2)"
-AT_DEBUG="$(uci_get lpac at debug 0)"
-
 export LPAC_HTTP="$HTTP_BACKEND"
 if [ "$HTTP_DEBUG" -eq 1 ]; then
     export LIBEUICC_DEBUG_HTTP="1"
@@ -21,7 +18,16 @@ if [ "$APDU_DEBUG" -eq 1 ]; then
     export LIBEUICC_DEBUG_APDU="1"
 fi
 
-export AT_DEVICE="$AT_DEVICE"
-export AT_DEBUG="$AT_DEBUG"
+if [ "$APDU_BACKEND" = "at" ]; then
+    AT_DEVICE="$(uci_get lpac at device /dev/ttyUSB2)"
+    AT_DEBUG="$(uci_get lpac at debug 0)"
+    export AT_DEVICE="$AT_DEVICE"
+    export AT_DEBUG="$AT_DEBUG"
+elif [ "$APDU_BACKEND" = "uqmi" ]; then
+    UQMI_DEV="$(uci_get lpac uqmi device /dev/cdc-wdm0)"
+    UQMI_DEBUG="$(uci_get lpac uqmi debug 0)"
+    export LPAC_QMI_DEV="$UQMI_DEV"
+    export LPAC_QMI_DEBUG="$UQMI_DEBUG"
+fi
 
 /usr/lib/lpac "$@"

utils/lpac/files/lpac.uci

@@ -1,9 +1,13 @@
 config global global
-	option		apdu_backend	'at'
+	option		apdu_backend	'uqmi'
 	option		http_backend	'curl'
 	option		apdu_debug	'0'
 	option		http_debug	'0'
 
 config at at
 	option		device		'/dev/ttyUSB2'
 	option		debug		'0'
+
+config uqmi uqmi
+	option		device		'/dev/cdc-wdm0'
+	option		debug		'0'