net: ipa: optionally define firmware name via DT

IPA initialization includes loading some firmware.  This step is
done either by the modem or by the AP under Trust Zone.  If the
AP loads firmware, the name of the firmware file is currently
hard-coded ("ipa_fws.mdt").

Add the ability to specify the relative path of the firmware file to
use in a property in the Device Tree IPA node.  If the property is
not found (or if any other error occurs attempting to get it), fall
back to using a default relative path.

Use the "old" fixed name as the default.  Rename the symbol that
represents this default to emphasize its purpose.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ipa/ipa_main.c

@@ -67,7 +67,7 @@
  */
 
 /* The name of the GSI firmware file relative to /lib/firmware */
-#define IPA_FWS_PATH		"ipa_fws.mdt"
+#define IPA_FW_PATH_DEFAULT	"ipa_fws.mdt"
 #define IPA_PAS_ID		15
 
 /* Shift of 19.2 MHz timestamp to achieve lower resolution timestamps */
@@ -517,6 +517,7 @@ static int ipa_firmware_load(struct device *dev)
 	struct device_node *node;
 	struct resource res;
 	phys_addr_t phys;
+	const char *path;
 	ssize_t size;
 	void *virt;
 	int ret;
@@ -534,9 +535,17 @@ static int ipa_firmware_load(struct device *dev)
 		return ret;
 	}
 
-	ret = request_firmware(&fw, IPA_FWS_PATH, dev);
+	/* Use name from DTB if specified; use default for *any* error */
+	ret = of_property_read_string(dev->of_node, "firmware-name", &path);
 	if (ret) {
-		dev_err(dev, "error %d requesting \"%s\"\n", ret, IPA_FWS_PATH);
+		dev_dbg(dev, "error %d getting \"firmware-name\" resource\n",
+			ret);
+		path = IPA_FW_PATH_DEFAULT;
+	}
+
+	ret = request_firmware(&fw, path, dev);
+	if (ret) {
+		dev_err(dev, "error %d requesting \"%s\"\n", ret, path);
 		return ret;
 	}
 
@@ -549,13 +558,11 @@ static int ipa_firmware_load(struct device *dev)
 		goto out_release_firmware;
 	}
 
-	ret = qcom_mdt_load(dev, fw, IPA_FWS_PATH, IPA_PAS_ID,
-			    virt, phys, size, NULL);
+	ret = qcom_mdt_load(dev, fw, path, IPA_PAS_ID, virt, phys, size, NULL);
 	if (ret)
-		dev_err(dev, "error %d loading \"%s\"\n", ret, IPA_FWS_PATH);
+		dev_err(dev, "error %d loading \"%s\"\n", ret, path);
 	else if ((ret = qcom_scm_pas_auth_and_reset(IPA_PAS_ID)))
-		dev_err(dev, "error %d authenticating \"%s\"\n", ret,
-			IPA_FWS_PATH);
+		dev_err(dev, "error %d authenticating \"%s\"\n", ret, path);
 
 	memunmap(virt);
 out_release_firmware: