NFC: Digital Protocol stack implementation

This is the initial commit of the NFC Digital Protocol stack
implementation.

It offers an interface for devices that don't have an embedded NFC
Digital protocol stack. The driver instantiates the digital stack by
calling nfc_digital_allocate_device(). Within the nfc_digital_ops
structure, the driver specifies a set of function pointers for driver
operations. These functions must be implemented by the driver and are:

in_configure_hw:
Hardware configuration for RF technology and communication framing in
initiator mode. This is a synchronous function.

in_send_cmd:
Initiator mode data exchange using RF technology and framing previously
set with in_configure_hw. The peer response is returned through
callback cb. If an io error occurs or the peer didn't reply within the
specified timeout (ms), the error code is passed back through the resp
pointer. This is an asynchronous function.

tg_configure_hw:
Hardware configuration for RF technology and communication framing in
target mode. This is a synchronous function.

tg_send_cmd:
Target mode data exchange using RF technology and framing previously
set with tg_configure_hw. The peer next command is returned through
callback cb. If an io error occurs or the peer didn't reply within the
specified timeout (ms), the error code is passed back through the resp
pointer. This is an asynchronous function.

tg_listen:
Put the device in listen mode waiting for data from the peer device.
This is an asynchronous function.

tg_listen_mdaa:
If supported, put the device in automatic listen mode with mode
detection and automatic anti-collision. In this mode, the device
automatically detects the RF technology and executes the
anti-collision detection using the command responses specified in
mdaa_params. The mdaa_params structure contains SENS_RES, NFCID1, and
SEL_RES for 106A RF tech. NFCID2 and system code (sc) for 212F and
424F. The driver returns the NFC-DEP ATR_REQ command through cb. The
digital stack deducts the RF tech by analyzing the SoD of the frame
containing the ATR_REQ command. This is an asynchronous function.

switch_rf:
Turns device radio on or off. The stack does not call explicitly
switch_rf to turn the radio on. A call to in|tg_configure_hw must turn
the device radio on.

abort_cmd:
Discard the last sent command.

Then the driver registers itself against the digital stack by using
nfc_digital_register_device() which in turn registers the digital stack
against the NFC core layer. The digital stack implements common NFC
operations like dev_up(), dev_down(), start_poll(), stop_poll(), etc.

This patch is only a skeleton and NFC operations are just stubs.

Signed-off-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

4 files changed, 192 insertions, 0 deletions

diff --git a/net/nfc/Kconfig b/net/nfc/Kconfig
index 5948b2f..13e1237 100644
--- a/net/nfc/Kconfig
+++ b/net/nfc/Kconfig
@@ -14,6 +14,18 @@ menuconfig NFC
 	  To compile this support as a module, choose M here: the module will
 	  be called nfc.
 
+config NFC_DIGITAL
+	depends on NFC
+	tristate "NFC Digital Protocol stack support"
+	default n
+	help
+	  Say Y if you want to build NFC digital protocol stack support.
+	  This is needed by NFC chipsets whose firmware only implement
+	  the NFC analog layer.
+
+	  To compile this support as a module, choose M here: the module will
+	  be called nfc_digital.
+
 source "net/nfc/nci/Kconfig"
 source "net/nfc/hci/Kconfig"
 
diff --git a/net/nfc/Makefile b/net/nfc/Makefile
index a76f453..8e0cabd 100644
--- a/net/nfc/Makefile
+++ b/net/nfc/Makefile
@@ -5,7 +5,9 @@
 obj-$(CONFIG_NFC) += nfc.o
 obj-$(CONFIG_NFC_NCI) += nci/
 obj-$(CONFIG_NFC_HCI) += hci/
+obj-$(CONFIG_NFC_DIGITAL) += nfc_digital.o
 
 nfc-objs := core.o netlink.o af_nfc.o rawsock.o llcp_core.o llcp_commands.o \
 		llcp_sock.o
 
+nfc_digital-objs := digital_core.o
diff --git a/net/nfc/digital.h b/net/nfc/digital.h
new file mode 100644
index 0000000..8d91ed8
--- /dev/null
+++ b/net/nfc/digital.h
@@ -0,0 +1,27 @@
+/*
+ * NFC Digital Protocol stack
+ * Copyright (c) 2013, Intel Corporation.
+ *
+ * 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 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.
+ *
+ */
+
+#ifndef __DIGITAL_H
+#define __DIGITAL_H
+
+#include <net/nfc/nfc.h>
+#include <net/nfc/digital.h>
+
+#define PR_DBG(fmt, ...)  pr_debug("%s: " fmt "\n", __func__, ##__VA_ARGS__)
+#define PR_ERR(fmt, ...)  pr_err("%s: " fmt "\n", __func__, ##__VA_ARGS__)
+#define PROTOCOL_ERR(req) pr_err("%s:%d: NFC Digital Protocol error: %s\n", \
+				 __func__, __LINE__, req)
+
+#endif /* __DIGITAL_H */
diff --git a/net/nfc/digital_core.c b/net/nfc/digital_core.c
new file mode 100644
index 0000000..471188a
--- /dev/null
+++ b/net/nfc/digital_core.c
@@ -0,0 +1,151 @@
+/*
+ * NFC Digital Protocol stack
+ * Copyright (c) 2013, Intel Corporation.
+ *
+ * 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 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.
+ *
+ */
+
+#include <linux/module.h>
+
+#include "digital.h"
+
+static int digital_start_poll(struct nfc_dev *nfc_dev, __u32 im_protocols,
+			      __u32 tm_protocols)
+{
+	return -EOPNOTSUPP;
+}
+
+static void digital_stop_poll(struct nfc_dev *nfc_dev)
+{
+}
+
+static int digital_dev_up(struct nfc_dev *nfc_dev)
+{
+	return -EOPNOTSUPP;
+}
+
+static int digital_dev_down(struct nfc_dev *nfc_dev)
+{
+	return -EOPNOTSUPP;
+}
+
+static int digital_dep_link_up(struct nfc_dev *nfc_dev,
+			       struct nfc_target *target,
+			       __u8 comm_mode, __u8 *gb, size_t gb_len)
+{
+	return -EOPNOTSUPP;
+}
+
+static int digital_dep_link_down(struct nfc_dev *nfc_dev)
+{
+	return -EOPNOTSUPP;
+}
+
+static int digital_activate_target(struct nfc_dev *nfc_dev,
+				   struct nfc_target *target, __u32 protocol)
+{
+	return -EOPNOTSUPP;
+}
+
+static void digital_deactivate_target(struct nfc_dev *nfc_dev,
+				      struct nfc_target *target)
+{
+}
+
+static int digital_tg_send(struct nfc_dev *dev, struct sk_buff *skb)
+{
+	return -EOPNOTSUPP;
+}
+
+static int digital_in_send(struct nfc_dev *nfc_dev, struct nfc_target *target,
+			   struct sk_buff *skb, data_exchange_cb_t cb,
+			   void *cb_context)
+{
+	return -EOPNOTSUPP;
+}
+
+static struct nfc_ops digital_nfc_ops = {
+	.dev_up = digital_dev_up,
+	.dev_down = digital_dev_down,
+	.start_poll = digital_start_poll,
+	.stop_poll = digital_stop_poll,
+	.dep_link_up = digital_dep_link_up,
+	.dep_link_down = digital_dep_link_down,
+	.activate_target = digital_activate_target,
+	.deactivate_target = digital_deactivate_target,
+	.tm_send = digital_tg_send,
+	.im_transceive = digital_in_send,
+};
+
+struct nfc_digital_dev *nfc_digital_allocate_device(struct nfc_digital_ops *ops,
+					    __u32 supported_protocols,
+					    __u32 driver_capabilities,
+					    int tx_headroom, int tx_tailroom)
+{
+	struct nfc_digital_dev *ddev;
+
+	if (!ops->in_configure_hw || !ops->in_send_cmd || !ops->tg_listen ||
+	    !ops->tg_configure_hw || !ops->tg_send_cmd || !ops->abort_cmd ||
+	    !ops->switch_rf)
+		return NULL;
+
+	ddev = kzalloc(sizeof(struct nfc_digital_dev), GFP_KERNEL);
+	if (!ddev) {
+		PR_ERR("kzalloc failed");
+		return NULL;
+	}
+
+	ddev->driver_capabilities = driver_capabilities;
+	ddev->ops = ops;
+
+	ddev->tx_headroom = tx_headroom;
+	ddev->tx_tailroom = tx_tailroom;
+
+	ddev->nfc_dev = nfc_allocate_device(&digital_nfc_ops, ddev->protocols,
+					    ddev->tx_headroom,
+					    ddev->tx_tailroom);
+	if (!ddev->nfc_dev) {
+		PR_ERR("nfc_allocate_device failed");
+		goto free_dev;
+	}
+
+	nfc_set_drvdata(ddev->nfc_dev, ddev);
+
+	return ddev;
+
+free_dev:
+	kfree(ddev);
+
+	return NULL;
+}
+EXPORT_SYMBOL(nfc_digital_allocate_device);
+
+void nfc_digital_free_device(struct nfc_digital_dev *ddev)
+{
+	nfc_free_device(ddev->nfc_dev);
+
+	kfree(ddev);
+}
+EXPORT_SYMBOL(nfc_digital_free_device);
+
+int nfc_digital_register_device(struct nfc_digital_dev *ddev)
+{
+	return nfc_register_device(ddev->nfc_dev);
+}
+EXPORT_SYMBOL(nfc_digital_register_device);
+
+void nfc_digital_unregister_device(struct nfc_digital_dev *ddev)
+{
+	nfc_unregister_device(ddev->nfc_dev);
+}
+EXPORT_SYMBOL(nfc_digital_unregister_device);
+
+MODULE_LICENSE("GPL");