net: ipa: permit GSI firmware loading to be skipped

Define a new value "skip" for the "qcom,gsi-loader" Device Tree
property.  If used, it indicates that neither the AP nor the modem
need to load GSI firmware (because it has already been loaded--for
example by the boot loader).
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ipa/ipa_main.c

@@ -87,12 +87,14 @@
  * @IPA_LOADER_DEFER:		System not ready; try again later
  * @IPA_LOADER_SELF:		AP loads GSI firmware
  * @IPA_LOADER_MODEM:		Modem loads GSI firmware, signals when done
+ * @IPA_LOADER_SKIP:		Neither AP nor modem need to load GSI firmware
  * @IPA_LOADER_INVALID:	GSI firmware loader specification is invalid
  */
 enum ipa_firmware_loader {
 	IPA_LOADER_DEFER,
 	IPA_LOADER_SELF,
 	IPA_LOADER_MODEM,
+	IPA_LOADER_SKIP,
 	IPA_LOADER_INVALID,
 };
 
@@ -740,6 +742,10 @@ static enum ipa_firmware_loader ipa_firmware_loader(struct device *dev)
 	if (!strcmp(str, "modem"))
 		return IPA_LOADER_MODEM;
 
+	/* No GSI firmware load is needed for "skip" */
+	if (!strcmp(str, "skip"))
+		return IPA_LOADER_SKIP;
+
 	/* Any value other than "self" is an error */
 	if (strcmp(str, "self"))
 		return IPA_LOADER_INVALID;
@@ -872,10 +878,12 @@ static int ipa_probe(struct platform_device *pdev)
 	if (loader == IPA_LOADER_MODEM)
 		goto done;
 
+	if (loader == IPA_LOADER_SELF) {
 		/* The AP is loading GSI firmware; do so now */
 		ret = ipa_firmware_load(dev);
 		if (ret)
 			goto err_deconfig;
+	} /* Otherwise loader == IPA_LOADER_SKIP */
 
 	/* GSI firmware is loaded; proceed to setup */
 	ret = ipa_setup(ipa);