NVIDIA: VR: SAUCE: firmware: smccc: lfa: Emit a uevent on inventory updates

Firmware image directories are plain kobjects under /sys/firmware.
udev coldplug does not enumerate them as devices, so rules matching
the per-image LFA kobjects do not run reliably at boot.

LFA already creates the arm-lfa faux device. Emit KOBJ_CHANGE from
that device after the firmware image tree is refreshed, so user space
can use the existing driver-core device as the notification anchor
for runtime inventory updates. The same udev rule then also covers
coldplug via the device add event, e.g.:

  ACTION=="add|change", SUBSYSTEM=="faux", KERNEL=="arm-lfa", \
          RUN+="/usr/local/sbin/lfa-auto-activate"

Signed-off-by: Nirmoy Das <nirmoyd@nvidia.com>

Author: nirmoy

drivers/firmware/smccc/lfa_fw.c

@@ -154,6 +154,7 @@ static const struct fw_image_uuid {
 };
 
 static struct kset *lfa_kset;
+static struct faux_device *lfa_dev;
 static struct workqueue_struct *fw_images_update_wq;
 static struct work_struct fw_images_update_work;
 static struct attribute *image_default_attrs[LFA_ATTR_NR_IMAGES + 1];
@@ -241,6 +242,21 @@ static void remove_invalid_fw_images(struct work_struct *work)
 
 		delete_fw_image_node(image);
 	}
+
+	/*
+	 * Notify user space only after the firmware image tree has been
+	 * fully reconciled, so that consumers reading /sys/firmware/lfa/
+	 * see a settled inventory.  Anchor the event on the arm-lfa faux
+	 * device because the per-image kobjects under /sys/firmware/ are
+	 * not enumerated by udev coldplug.
+	 */
+	if (lfa_dev) {
+		int ret = kobject_uevent(&lfa_dev->dev.kobj, KOBJ_CHANGE);
+
+		if (ret)
+			pr_warn("failed to send firmware inventory change uevent: %d\n",
+				ret);
+	}
 }
 
 static void set_image_flags(struct fw_image *image, int seq_id,
@@ -967,7 +983,6 @@ static void lfa_faux_remove(struct faux_device *fdev)
 	lfa_remove_acpi(&fdev->dev);
 }
 
-static struct faux_device *lfa_dev;
 static struct faux_device_ops lfa_device_ops = {
 	.probe = lfa_faux_probe,
 	.remove = lfa_faux_remove,