NFC: Add a target lost netlink event

Some chips are capable of detecting when a tag is out of the field, so
they could send a netlink event about it to userspace.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/nfc.h

@@ -70,6 +70,7 @@ enum nfc_commands {
 	NFC_EVENT_TARGETS_FOUND,
 	NFC_EVENT_DEVICE_ADDED,
 	NFC_EVENT_DEVICE_REMOVED,
+	NFC_EVENT_TARGET_LOST,
 /* private: internal use only */
 	__NFC_CMD_AFTER_LAST
 };

net/nfc/netlink.c

@@ -183,6 +183,36 @@ int nfc_genl_targets_found(struct nfc_dev *dev)
 	return -EMSGSIZE;
 }
 
+int nfc_genl_target_lost(struct nfc_dev *dev, u32 target_idx)
+{
+	struct sk_buff *msg;
+	void *hdr;
+
+	msg = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	hdr = genlmsg_put(msg, 0, 0, &nfc_genl_family, 0,
+			  NFC_EVENT_TARGET_LOST);
+	if (!hdr)
+		goto free_msg;
+
+	NLA_PUT_STRING(msg, NFC_ATTR_DEVICE_NAME, nfc_device_name(dev));
+	NLA_PUT_U32(msg, NFC_ATTR_TARGET_INDEX, target_idx);
+
+	genlmsg_end(msg, hdr);
+
+	genlmsg_multicast(msg, 0, nfc_genl_event_mcgrp.id, GFP_KERNEL);
+
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+free_msg:
+	nlmsg_free(msg);
+	return -EMSGSIZE;
+}
+
 int nfc_genl_device_added(struct nfc_dev *dev)
 {
 	struct sk_buff *msg;

net/nfc/nfc.h

@@ -119,6 +119,7 @@ void nfc_genl_data_init(struct nfc_genl_data *genl_data);
 void nfc_genl_data_exit(struct nfc_genl_data *genl_data);
 
 int nfc_genl_targets_found(struct nfc_dev *dev);
+int nfc_genl_target_lost(struct nfc_dev *dev, u32 target_idx);
 
 int nfc_genl_device_added(struct nfc_dev *dev);
 int nfc_genl_device_removed(struct nfc_dev *dev);