media: rc: expose most recent raw packet via sysfs

index 1042fa3..1b1ae6d 100644
@@ -1246,6 +1246,47 @@ unlock:
 	return (ret < 0) ? ret : len;
 }
 
+/**
+ * last_raw_packet_read() - shows the most recent packet of raw bytes
+ * This is a binary attribute.
+ *
+ * This routine is a callback routine to read the most recent packet of
+ * raw bytes received.
+ * It is triggered by reading /sys/class/rc/rc?/last_raw_packet.
+ * Most recent means up to BUF_SYSFS_LRP_SZ bytes after the last break
+ * of at least RESTART_SYSFS_LRP_MS milliseconds.
+ *
+ * Primary use is assembling a wakeup sequence for chips supporting this
+ * feature (e.g. nuvoton-cir). Apart from that it can be used for
+ * debugging purposes.
+ */
+static ssize_t last_raw_packet_read(struct file *fp, struct kobject *kobj,
+				    struct bin_attribute *attr, char *buf,
+				    loff_t off, size_t count)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct rc_dev *rc_dev = to_rc_dev(dev);
+	unsigned long flags;
+	size_t cnt;
+
+	if (!rc_dev->raw)
+		return 0;
+
+	spin_lock_irqsave(&rc_dev->raw->lock, flags);
+
+	if (off >= rc_dev->raw->buf_sysfs_lrp_cnt) {
+		spin_unlock_irqrestore(&rc_dev->raw->lock, flags);
+		return 0;
+	}
+
+	cnt = min_t(size_t, count, rc_dev->raw->buf_sysfs_lrp_cnt - off);
+	memcpy(buf, rc_dev->raw->buf_sysfs_lrp + off, cnt);
+
+	spin_unlock_irqrestore(&rc_dev->raw->lock, flags);
+
+	return cnt;
+}
+
 static void rc_dev_release(struct device *device)
 {
 }

@@ -1284,6 +1325,7 @@ static RC_FILTER_ATTR(wakeup_filter, S_IRUGO|S_IWUSR,
 		      show_filter, store_filter, RC_FILTER_WAKEUP, false);
 static RC_FILTER_ATTR(wakeup_filter_mask, S_IRUGO|S_IWUSR,
 		      show_filter, store_filter, RC_FILTER_WAKEUP, true);
+static BIN_ATTR_RO(last_raw_packet, BUF_SYSFS_LRP_SZ);
 
 static struct attribute *rc_dev_protocol_attrs[] = {
 	&dev_attr_protocols.attr.attr,

@@ -1323,6 +1365,15 @@ static struct attribute_group rc_dev_wakeup_filter_attr_grp = {
 	.attrs	= rc_dev_wakeup_filter_attrs,
 };
 
+static struct bin_attribute *rc_dev_raw_lrp_attrs[] = {
+	&bin_attr_last_raw_packet,
+	NULL,
+};
+
+static struct attribute_group rc_dev_raw_lrp_attr_grp = {
+	.bin_attrs = rc_dev_raw_lrp_attrs,
+};
+
 static struct device_type rc_dev_type = {
 	.release	= rc_dev_release,
 	.uevent		= rc_dev_uevent,

@@ -1417,6 +1468,8 @@ int rc_register_device(struct rc_dev *dev)
 		dev->sysfs_groups[attr++] = &rc_dev_wakeup_filter_attr_grp;
 	if (dev->change_wakeup_protocol)
 		dev->sysfs_groups[attr++] = &rc_dev_wakeup_protocol_attr_grp;
+	if (dev->enable_sysfs_lrp)
+		dev->sysfs_groups[attr++] = &rc_dev_raw_lrp_attr_grp;
 	dev->sysfs_groups[attr++] = NULL;
 
 	/*

index 9542891..e2d89ea 100644
@@ -122,7 +122,7 @@ enum rc_filter_type {
  */
 struct rc_dev {
 	struct device			dev;
-	const struct attribute_group	*sysfs_groups[5];
+	const struct attribute_group	*sysfs_groups[6];
 	const char			*input_name;
 	const char			*input_phys;
 	struct input_id			input_id;