NFC: Add a GET_SE netlink API

In order to fetch the discovered secure elements from an NFC controller,
we need to send a netlink command that will dump the list of available
SEs from NFC.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

include/uapi/linux/nfc.h

@@ -84,6 +84,7 @@
  * @NFC_EVENT_SE_TRANSACTION: This event is sent when an application running on
  *	a specific SE notifies us about the end of a transaction. The parameter
  *	for this event is the application ID (AID).
+ * @NFC_CMD_GET_SE: Dump all discovered secure elements from an NFC controller.
  */
 enum nfc_commands {
 	NFC_CMD_UNSPEC,
@@ -112,6 +113,7 @@ enum nfc_commands {
 	NFC_EVENT_SE_REMOVED,
 	NFC_EVENT_SE_CONNECTIVITY,
 	NFC_EVENT_SE_TRANSACTION,
+	NFC_CMD_GET_SE,
 /* private: internal use only */
 	__NFC_CMD_AFTER_LAST
 };

net/nfc/netlink.c

@@ -1191,6 +1191,91 @@ static int nfc_genl_disable_se(struct sk_buff *skb, struct genl_info *info)
 	return rc;
 }
 
+static int nfc_genl_send_se(struct sk_buff *msg, struct nfc_dev *dev,
+				u32 portid, u32 seq,
+				struct netlink_callback *cb,
+				int flags)
+{
+	void *hdr;
+	struct nfc_se *se, *n;
+
+	list_for_each_entry_safe(se, n, &dev->secure_elements, list) {
+		hdr = genlmsg_put(msg, portid, seq, &nfc_genl_family, flags,
+				  NFC_CMD_GET_SE);
+		if (!hdr)
+			goto nla_put_failure;
+
+		if (cb)
+			genl_dump_check_consistent(cb, hdr, &nfc_genl_family);
+
+		if (nla_put_u32(msg, NFC_ATTR_DEVICE_INDEX, dev->idx) ||
+		    nla_put_u32(msg, NFC_ATTR_SE_INDEX, se->idx) ||
+		    nla_put_u8(msg, NFC_ATTR_SE_TYPE, se->type))
+			goto nla_put_failure;
+
+		if (genlmsg_end(msg, hdr) < 0)
+			goto nla_put_failure;
+	}
+
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+static int nfc_genl_dump_ses(struct sk_buff *skb,
+				 struct netlink_callback *cb)
+{
+	struct class_dev_iter *iter = (struct class_dev_iter *) cb->args[0];
+	struct nfc_dev *dev = (struct nfc_dev *) cb->args[1];
+	bool first_call = false;
+
+	if (!iter) {
+		first_call = true;
+		iter = kmalloc(sizeof(struct class_dev_iter), GFP_KERNEL);
+		if (!iter)
+			return -ENOMEM;
+		cb->args[0] = (long) iter;
+	}
+
+	mutex_lock(&nfc_devlist_mutex);
+
+	cb->seq = nfc_devlist_generation;
+
+	if (first_call) {
+		nfc_device_iter_init(iter);
+		dev = nfc_device_iter_next(iter);
+	}
+
+	while (dev) {
+		int rc;
+
+		rc = nfc_genl_send_se(skb, dev, NETLINK_CB(cb->skb).portid,
+					  cb->nlh->nlmsg_seq, cb, NLM_F_MULTI);
+		if (rc < 0)
+			break;
+
+		dev = nfc_device_iter_next(iter);
+	}
+
+	mutex_unlock(&nfc_devlist_mutex);
+
+	cb->args[1] = (long) dev;
+
+	return skb->len;
+}
+
+static int nfc_genl_dump_ses_done(struct netlink_callback *cb)
+{
+	struct class_dev_iter *iter = (struct class_dev_iter *) cb->args[0];
+
+	nfc_device_iter_exit(iter);
+	kfree(iter);
+
+	return 0;
+}
+
 static struct genl_ops nfc_genl_ops[] = {
 	{
 		.cmd = NFC_CMD_GET_DEVICE,
@@ -1265,6 +1350,12 @@ static struct genl_ops nfc_genl_ops[] = {
 		.doit = nfc_genl_disable_se,
 		.policy = nfc_genl_policy,
 	},
+	{
+		.cmd = NFC_CMD_GET_SE,
+		.dumpit = nfc_genl_dump_ses,
+		.done = nfc_genl_dump_ses_done,
+		.policy = nfc_genl_policy,
+	},
 };