NFC: Initial LLCP support

This patch is an initial implementation for the NFC Logical Link Control
protocol. It's also known as NFC peer to peer mode.
This is a basic implementation as it lacks SDP (services Discovery
Protocol), frames aggregation support, and frame rejecion parsing.
Follow up patches will implement those missing features.
This code has been tested against a Nexus S phone implementing LLCP 1.0.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 399 insertions, 0 deletions

diff --git a/net/nfc/llcp/commands.c b/net/nfc/llcp/commands.c
new file mode 100644
index 000000000000..151f2ef429c4
--- /dev/null
+++ b/net/nfc/llcp/commands.c
@@ -0,0 +1,399 @@
+/*
+ * Copyright (C) 2011  Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#define pr_fmt(fmt) "llcp: %s: " fmt, __func__
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/nfc.h>
+
+#include <net/nfc/nfc.h>
+
+#include "../nfc.h"
+#include "llcp.h"
+
+static u8 llcp_tlv_length[LLCP_TLV_MAX] = {
+	0,
+	1, /* VERSION */
+	2, /* MIUX */
+	2, /* WKS */
+	1, /* LTO */
+	1, /* RW */
+	0, /* SN */
+	1, /* OPT */
+	0, /* SDREQ */
+	2, /* SDRES */
+
+};
+
+static u8 llcp_tlv8(u8 *tlv, u8 type)
+{
+	if (tlv[0] != type || tlv[1] != llcp_tlv_length[tlv[0]])
+		return 0;
+
+	return tlv[2];
+}
+
+static u8 llcp_tlv16(u8 *tlv, u8 type)
+{
+	if (tlv[0] != type || tlv[1] != llcp_tlv_length[tlv[0]])
+		return 0;
+
+	return be16_to_cpu(*((__be16 *)(tlv + 2)));
+}
+
+
+static u8 llcp_tlv_version(u8 *tlv)
+{
+	return llcp_tlv8(tlv, LLCP_TLV_VERSION);
+}
+
+static u16 llcp_tlv_miux(u8 *tlv)
+{
+	return llcp_tlv16(tlv, LLCP_TLV_MIUX) & 0x7f;
+}
+
+static u16 llcp_tlv_wks(u8 *tlv)
+{
+	return llcp_tlv16(tlv, LLCP_TLV_WKS);
+}
+
+static u16 llcp_tlv_lto(u8 *tlv)
+{
+	return llcp_tlv8(tlv, LLCP_TLV_LTO);
+}
+
+static u8 llcp_tlv_opt(u8 *tlv)
+{
+	return llcp_tlv8(tlv, LLCP_TLV_OPT);
+}
+
+static u8 llcp_tlv_rw(u8 *tlv)
+{
+	return llcp_tlv8(tlv, LLCP_TLV_RW) & 0xf;
+}
+
+u8 *nfc_llcp_build_tlv(u8 type, u8 *value, u8 value_length, u8 *tlv_length)
+{
+	u8 *tlv, length;
+
+	pr_debug("type %d\n", type);
+
+	if (type >= LLCP_TLV_MAX)
+		return NULL;
+
+	length = llcp_tlv_length[type];
+	if (length == 0 && value_length == 0)
+		return NULL;
+	else
+		length = value_length;
+
+	*tlv_length = 2 + length;
+	tlv = kzalloc(2 + length, GFP_KERNEL);
+	if (tlv == NULL)
+		return tlv;
+
+	tlv[0] = type;
+	tlv[1] = length;
+	memcpy(tlv + 2, value, length);
+
+	return tlv;
+}
+
+int nfc_llcp_parse_tlv(struct nfc_llcp_local *local,
+			u8 *tlv_array, u16 tlv_array_len)
+{
+	u8 *tlv = tlv_array, type, length, offset = 0;
+
+	pr_debug("TLV array length %d\n", tlv_array_len);
+
+	if (local == NULL)
+		return -ENODEV;
+
+	while (offset < tlv_array_len) {
+		type = tlv[0];
+		length = tlv[1];
+
+		pr_debug("type 0x%x length %d\n", type, length);
+
+		switch (type) {
+		case LLCP_TLV_VERSION:
+			local->remote_version = llcp_tlv_version(tlv);
+			break;
+		case LLCP_TLV_MIUX:
+			local->remote_miu = llcp_tlv_miux(tlv) + 128;
+			break;
+		case LLCP_TLV_WKS:
+			local->remote_wks = llcp_tlv_wks(tlv);
+			break;
+		case LLCP_TLV_LTO:
+			local->remote_lto = llcp_tlv_lto(tlv) * 10;
+			break;
+		case LLCP_TLV_OPT:
+			local->remote_opt = llcp_tlv_opt(tlv);
+			break;
+		case LLCP_TLV_RW:
+			local->remote_rw = llcp_tlv_rw(tlv);
+			break;
+		default:
+			pr_err("Invalid gt tlv value 0x%x\n", type);
+			break;
+		}
+
+		offset += length + 2;
+		tlv += length + 2;
+	}
+
+	pr_debug("version 0x%x miu %d lto %d opt 0x%x wks 0x%x rw %d\n",
+		local->remote_version, local->remote_miu,
+		local->remote_lto, local->remote_opt,
+		local->remote_wks, local->remote_rw);
+
+	return 0;
+}
+
+static struct sk_buff *llcp_add_header(struct sk_buff *pdu,
+					u8 dsap, u8 ssap, u8 ptype)
+{
+	u8 header[2];
+
+	pr_debug("ptype 0x%x dsap 0x%x ssap 0x%x\n", ptype, dsap, ssap);
+
+	header[0] = (u8)((dsap << 2) | (ptype >> 2));
+	header[1] = (u8)((ptype << 6) | ssap);
+
+	pr_debug("header 0x%x 0x%x\n", header[0], header[1]);
+
+	memcpy(skb_put(pdu, LLCP_HEADER_SIZE), header, LLCP_HEADER_SIZE);
+
+	return pdu;
+}
+
+static struct sk_buff *llcp_add_tlv(struct sk_buff *pdu, u8 *tlv, u8 tlv_length)
+{
+	/* XXX Add an skb length check */
+
+	if (tlv == NULL)
+		return NULL;
+
+	memcpy(skb_put(pdu, tlv_length), tlv, tlv_length);
+
+	return pdu;
+}
+
+static struct sk_buff *llcp_allocate_pdu(struct nfc_llcp_sock *sock,
+							u8 cmd, u16 size)
+{
+	struct sk_buff *skb;
+	int err;
+
+	if (sock->ssap == 0)
+		return NULL;
+
+	skb = nfc_alloc_send_skb(sock->dev, &sock->sk, MSG_DONTWAIT,
+					size + LLCP_HEADER_SIZE, &err);
+	if (skb == NULL) {
+		pr_err("Could not allocate PDU\n");
+		return NULL;
+	}
+
+	skb = llcp_add_header(skb, sock->dsap, sock->ssap, cmd);
+
+	return skb;
+}
+
+int nfc_llcp_disconnect(struct nfc_llcp_sock *sock)
+{
+	struct sk_buff *skb;
+	struct nfc_dev *dev;
+	struct nfc_llcp_local *local;
+	u16 size = 0;
+
+	pr_debug("Sending DISC\n");
+
+	local = sock->local;
+	if (local == NULL)
+		return -ENODEV;
+
+	dev = sock->dev;
+	if (dev == NULL)
+		return -ENODEV;
+
+	size += LLCP_HEADER_SIZE;
+	size += dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;
+
+	skb = alloc_skb(size, GFP_ATOMIC);
+	if (skb == NULL)
+		return -ENOMEM;
+
+	skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);
+
+	skb = llcp_add_header(skb, sock->ssap, sock->dsap, LLCP_PDU_DISC);
+
+	skb_queue_tail(&local->tx_queue, skb);
+
+	return 0;
+}
+
+int nfc_llcp_send_symm(struct nfc_dev *dev)
+{
+	struct sk_buff *skb;
+	struct nfc_llcp_local *local;
+	u16 size = 0;
+
+	pr_debug("Sending SYMM\n");
+
+	local = nfc_llcp_find_local(dev);
+	if (local == NULL)
+		return -ENODEV;
+
+	size += LLCP_HEADER_SIZE;
+	size += dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;
+
+	skb = alloc_skb(size, GFP_KERNEL);
+	if (skb == NULL)
+		return -ENOMEM;
+
+	skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);
+
+	skb = llcp_add_header(skb, 0, 0, LLCP_PDU_SYMM);
+
+	return nfc_data_exchange(dev, local->target_idx, skb,
+					nfc_llcp_recv, local);
+}
+
+int nfc_llcp_send_connect(struct nfc_llcp_sock *sock)
+{
+	struct nfc_llcp_local *local;
+	struct sk_buff *skb;
+	u8 *service_name_tlv = NULL, service_name_tlv_length;
+	int err;
+	u16 size = 0;
+
+	pr_debug("Sending CONNECT\n");
+
+	local = sock->local;
+	if (local == NULL)
+		return -ENODEV;
+
+	if (sock->service_name != NULL) {
+		service_name_tlv = nfc_llcp_build_tlv(LLCP_TLV_SN,
+					sock->service_name,
+					sock->service_name_len,
+					&service_name_tlv_length);
+		size += service_name_tlv_length;
+	}
+
+	pr_debug("SKB size %d SN length %zu\n", size, sock->service_name_len);
+
+	skb = llcp_allocate_pdu(sock, LLCP_PDU_CONNECT, size);
+	if (skb == NULL) {
+		err = -ENOMEM;
+		goto error_tlv;
+	}
+
+	if (service_name_tlv != NULL)
+		skb = llcp_add_tlv(skb, service_name_tlv,
+					service_name_tlv_length);
+
+	skb_queue_tail(&local->tx_queue, skb);
+
+	return 0;
+
+error_tlv:
+	pr_err("error %d\n", err);
+
+	kfree(service_name_tlv);
+
+	return err;
+}
+
+int nfc_llcp_send_cc(struct nfc_llcp_sock *sock)
+{
+	struct nfc_llcp_local *local;
+	struct sk_buff *skb;
+
+	pr_debug("Sending CC\n");
+
+	local = sock->local;
+	if (local == NULL)
+		return -ENODEV;
+
+	skb = llcp_allocate_pdu(sock, LLCP_PDU_CC, 0);
+	if (skb == NULL)
+		return -ENOMEM;
+
+	skb_queue_tail(&local->tx_queue, skb);
+
+	return 0;
+}
+
+int nfc_llcp_send_dm(struct nfc_llcp_local *local, u8 ssap, u8 dsap, u8 reason)
+{
+	struct sk_buff *skb;
+	struct nfc_dev *dev;
+	u16 size = 1; /* Reason code */
+
+	pr_debug("Sending DM reason 0x%x\n", reason);
+
+	if (local == NULL)
+		return -ENODEV;
+
+	dev = local->dev;
+	if (dev == NULL)
+		return -ENODEV;
+
+	size += LLCP_HEADER_SIZE;
+	size += dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;
+
+	skb = alloc_skb(size, GFP_KERNEL);
+	if (skb == NULL)
+		return -ENOMEM;
+
+	skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);
+
+	skb = llcp_add_header(skb, ssap, dsap, LLCP_PDU_DM);
+
+	memcpy(skb_put(skb, 1), &reason, 1);
+
+	skb_queue_head(&local->tx_queue, skb);
+
+	return 0;
+}
+
+int nfc_llcp_send_disconnect(struct nfc_llcp_sock *sock)
+{
+	struct sk_buff *skb;
+	struct nfc_llcp_local *local;
+
+	pr_debug("Send DISC\n");
+
+	local = sock->local;
+	if (local == NULL)
+		return -ENODEV;
+
+	skb = llcp_allocate_pdu(sock, LLCP_PDU_DISC, 0);
+	if (skb == NULL)
+		return -ENOMEM;
+
+	skb_queue_head(&local->tx_queue, skb);
+
+	return 0;
+}