NFC: Add a nop (passthrough) llc module to llc core

This is a passthrough llc. It can be used by HCI drivers that don't
need link layer control. HCI will then write directly to the driver, and
driver will deliver incoming frames directly to HCI without any
processing.
Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

include/net/nfc/llc.h

@@ -24,6 +24,8 @@
 #include <net/nfc/hci.h>
 #include <linux/skbuff.h>
 
+#define LLC_NOP_NAME "nop"
+
 typedef void (*rcv_to_hci_t) (struct nfc_hci_dev *hdev, struct sk_buff *skb);
 typedef int (*xmit_to_drv_t) (struct nfc_hci_dev *hdev, struct sk_buff *skb);
 typedef void (*llc_failure_t) (struct nfc_hci_dev *hdev, int err);

net/nfc/hci/Makefile

@@ -4,5 +4,5 @@
 
 obj-$(CONFIG_NFC_HCI) += hci.o
 
-hci-y			:= core.o hcp.o command.o llc.o
+hci-y			:= core.o hcp.o command.o llc.o llc_nop.o
 hci-$(CONFIG_NFC_SHDLC)	+= shdlc.o

net/nfc/hci/llc.c

@@ -28,7 +28,7 @@ int nfc_llc_init(void)
 {
 	INIT_LIST_HEAD(&llc_engines);
 
-	return 0;
+	return nfc_llc_nop_register();
 }
 EXPORT_SYMBOL(nfc_llc_init);
 

net/nfc/hci/llc.h

@@ -55,4 +55,6 @@ void *nfc_llc_get_data(struct nfc_llc *llc);
 int nfc_llc_register(const char *name, struct nfc_llc_ops *ops);
 void nfc_llc_unregister(const char *name);
 
+int nfc_llc_nop_register(void);
+
 #endif /* __LOCAL_LLC_H_ */

net/nfc/hci/llc_nop.c

+/*
+ * nop (passthrough) Link Layer Control
+ *
+ * Copyright (C) 2012  Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#include <linux/types.h>
+#include <linux/export.h>
+
+#include "llc.h"
+
+struct llc_nop {
+	struct nfc_hci_dev *hdev;
+	xmit_to_drv_t xmit_to_drv;
+	rcv_to_hci_t rcv_to_hci;
+	int tx_headroom;
+	int tx_tailroom;
+	llc_failure_t llc_failure;
+};
+
+static void *llc_nop_init(struct nfc_hci_dev *hdev, xmit_to_drv_t xmit_to_drv,
+			  rcv_to_hci_t rcv_to_hci, int tx_headroom,
+			  int tx_tailroom, int *rx_headroom, int *rx_tailroom,
+			  llc_failure_t llc_failure)
+{
+	struct llc_nop *llc_nop;
+
+	*rx_headroom = 0;
+	*rx_tailroom = 0;
+
+	llc_nop = kzalloc(sizeof(struct llc_nop), GFP_KERNEL);
+	if (llc_nop == NULL)
+		return NULL;
+
+	llc_nop->hdev = hdev;
+	llc_nop->xmit_to_drv = xmit_to_drv;
+	llc_nop->rcv_to_hci = rcv_to_hci;
+	llc_nop->tx_headroom = tx_headroom;
+	llc_nop->tx_tailroom = tx_tailroom;
+	llc_nop->llc_failure = llc_failure;
+
+	return llc_nop;
+}
+
+static void llc_nop_deinit(struct nfc_llc *llc)
+{
+	kfree(nfc_llc_get_data(llc));
+}
+
+static int llc_nop_start(struct nfc_llc *llc)
+{
+	return 0;
+}
+
+static int llc_nop_stop(struct nfc_llc *llc)
+{
+	return 0;
+}
+
+static void llc_nop_rcv_from_drv(struct nfc_llc *llc, struct sk_buff *skb)
+{
+	struct llc_nop *llc_nop = nfc_llc_get_data(llc);
+
+	llc_nop->rcv_to_hci(llc_nop->hdev, skb);
+}
+
+static int llc_nop_xmit_from_hci(struct nfc_llc *llc, struct sk_buff *skb)
+{
+	struct llc_nop *llc_nop = nfc_llc_get_data(llc);
+
+	return llc_nop->xmit_to_drv(llc_nop->hdev, skb);
+}
+
+static struct nfc_llc_ops llc_nop_ops = {
+	.init = llc_nop_init,
+	.deinit = llc_nop_deinit,
+	.start = llc_nop_start,
+	.stop = llc_nop_stop,
+	.rcv_from_drv = llc_nop_rcv_from_drv,
+	.xmit_from_hci = llc_nop_xmit_from_hci,
+};
+
+int nfc_llc_nop_register()
+{
+	return nfc_llc_register(LLC_NOP_NAME, &llc_nop_ops);
+}
+EXPORT_SYMBOL(nfc_llc_nop_register);