nfcwilink.c

/*
 *  Texas Instrument's NFC Driver For Shared Transport.
 *
 *  NFC Driver acts as interface between NCI core and
 *  TI Shared Transport Layer.
 *
 *  Copyright (C) 2011 Texas Instruments, Inc.
 *
 *  Written by Ilan Elias <ilane@ti.com>
 *
 *  Acknowledgements:
 *  This file is based on btwilink.c, which was written
 *  by Raja Mani and Pavan Savoy.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms 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/platform_device.h>
#include <linux/nfc.h>
#include <net/nfc/nci.h>
#include <net/nfc/nci_core.h>
#include <linux/ti_wilink_st.h>

#define NFCWILINK_CHNL			12
#define NFCWILINK_OPCODE		7
#define NFCWILINK_MAX_FRAME_SIZE	300
#define NFCWILINK_HDR_LEN		4
#define NFCWILINK_OFFSET_LEN_IN_HDR	1
#define NFCWILINK_LEN_SIZE		2
#define NFCWILINK_REGISTER_TIMEOUT	8000	/* 8 sec */

struct nfcwilink_hdr {
	u8 chnl;
	u8 opcode;
	u16 len;
} __packed;

struct nfcwilink {
	struct platform_device		*pdev;
	struct nci_dev			*ndev;
	unsigned long			flags;

	char				st_register_cb_status;
	long				(*st_write) (struct sk_buff *);
	struct completion		st_register_completed;
};

/* NFCWILINK driver flags */
enum {
	NFCWILINK_RUNNING,
};

/* Called by ST when registration is complete */
static void nfcwilink_register_complete(void *priv_data, char data)
{
	struct nfcwilink *drv = priv_data;

	nfc_dev_dbg(&drv->pdev->dev, "register_complete entry");

	/* store ST registration status */
	drv->st_register_cb_status = data;

	/* complete the wait in nfc_st_open() */
	complete(&drv->st_register_completed);
}

/* Called by ST when receive data is available */
static long nfcwilink_receive(void *priv_data, struct sk_buff *skb)
{
	struct nfcwilink *drv = priv_data;
	int rc;

	nfc_dev_dbg(&drv->pdev->dev, "receive entry, len %d", skb->len);

	if (!skb)
		return -EFAULT;

	if (!drv) {
		kfree_skb(skb);
		return -EFAULT;
	}

	/* strip the ST header
	(apart for the chnl byte, which is not received in the hdr) */
	skb_pull(skb, (NFCWILINK_HDR_LEN-1));

	skb->dev = (void *) drv->ndev;

	/* Forward skb to NCI core layer */
	rc = nci_recv_frame(skb);
	if (rc < 0) {
		nfc_dev_err(&drv->pdev->dev, "nci_recv_frame failed %d", rc);
		return rc;
	}

	return 0;
}

/* protocol structure registered with ST */
static struct st_proto_s nfcwilink_proto = {
	.chnl_id = NFCWILINK_CHNL,
	.max_frame_size = NFCWILINK_MAX_FRAME_SIZE,
	.hdr_len = (NFCWILINK_HDR_LEN-1),	/* not including chnl byte */
	.offset_len_in_hdr = NFCWILINK_OFFSET_LEN_IN_HDR,
	.len_size = NFCWILINK_LEN_SIZE,
	.reserve = 0,
	.recv = nfcwilink_receive,
	.reg_complete_cb = nfcwilink_register_complete,
	.write = NULL,
};

static int nfcwilink_open(struct nci_dev *ndev)
{
	struct nfcwilink *drv = nci_get_drvdata(ndev);
	unsigned long comp_ret;
	int rc;

	nfc_dev_dbg(&drv->pdev->dev, "open entry");

	if (test_and_set_bit(NFCWILINK_RUNNING, &drv->flags)) {
		rc = -EBUSY;
		goto exit;
	}

	nfcwilink_proto.priv_data = drv;

	init_completion(&drv->st_register_completed);
	drv->st_register_cb_status = -EINPROGRESS;

	rc = st_register(&nfcwilink_proto);
	if (rc < 0) {
		if (rc == -EINPROGRESS) {
			comp_ret = wait_for_completion_timeout(
			&drv->st_register_completed,
			msecs_to_jiffies(NFCWILINK_REGISTER_TIMEOUT));

			nfc_dev_dbg(&drv->pdev->dev,
			"wait_for_completion_timeout returned %ld",
			comp_ret);

			if (comp_ret == 0) {
				/* timeout */
				rc = -ETIMEDOUT;
				goto clear_exit;
			} else if (drv->st_register_cb_status != 0) {
				rc = drv->st_register_cb_status;
				nfc_dev_err(&drv->pdev->dev,
				"st_register_cb failed %d", rc);
				goto clear_exit;
			}
		} else {
			nfc_dev_err(&drv->pdev->dev,
				"st_register failed %d", rc);
			goto clear_exit;
		}
	}

	/* st_register MUST fill the write callback */
	BUG_ON(nfcwilink_proto.write == NULL);
	drv->st_write = nfcwilink_proto.write;

	goto exit;

clear_exit:
	clear_bit(NFCWILINK_RUNNING, &drv->flags);

exit:
	return rc;
}

static int nfcwilink_close(struct nci_dev *ndev)
{
	struct nfcwilink *drv = nci_get_drvdata(ndev);
	int rc;

	nfc_dev_dbg(&drv->pdev->dev, "close entry");

	if (!test_and_clear_bit(NFCWILINK_RUNNING, &drv->flags))
		return 0;

	rc = st_unregister(&nfcwilink_proto);
	if (rc)
		nfc_dev_err(&drv->pdev->dev, "st_unregister failed %d", rc);

	drv->st_write = NULL;

	return rc;
}

static int nfcwilink_send(struct sk_buff *skb)
{
	struct nci_dev *ndev = (struct nci_dev *)skb->dev;
	struct nfcwilink *drv = nci_get_drvdata(ndev);
	struct nfcwilink_hdr hdr = {NFCWILINK_CHNL, NFCWILINK_OPCODE, 0x0000};
	long len;

	nfc_dev_dbg(&drv->pdev->dev, "send entry, len %d", skb->len);

	if (!test_bit(NFCWILINK_RUNNING, &drv->flags))
		return -EBUSY;

	/* add the ST hdr to the start of the buffer */
	hdr.len = skb->len;
	memcpy(skb_push(skb, NFCWILINK_HDR_LEN), &hdr, NFCWILINK_HDR_LEN);

	/* Insert skb to shared transport layer's transmit queue.
	 * Freeing skb memory is taken care in shared transport layer,
	 * so don't free skb memory here.
	 */
	len = drv->st_write(skb);
	if (len < 0) {
		kfree_skb(skb);
		nfc_dev_err(&drv->pdev->dev, "st_write failed %ld", len);
		return -EFAULT;
	}

	return 0;
}

static struct nci_ops nfcwilink_ops = {
	.open = nfcwilink_open,
	.close = nfcwilink_close,
	.send = nfcwilink_send,
};

static int nfcwilink_probe(struct platform_device *pdev)
{
	static struct nfcwilink *drv;
	int rc;
	u32 protocols;

	nfc_dev_dbg(&pdev->dev, "probe entry");

	drv = kzalloc(sizeof(struct nfcwilink), GFP_KERNEL);
	if (!drv) {
		rc = -ENOMEM;
		goto exit;
	}

	drv->pdev = pdev;

	protocols = NFC_PROTO_JEWEL_MASK
			| NFC_PROTO_MIFARE_MASK | NFC_PROTO_FELICA_MASK
			| NFC_PROTO_ISO14443_MASK
			| NFC_PROTO_NFC_DEP_MASK;

	drv->ndev = nci_allocate_device(&nfcwilink_ops,
					protocols,
					NFCWILINK_HDR_LEN,
					0);
	if (!drv->ndev) {
		nfc_dev_err(&pdev->dev, "nci_allocate_device failed");
		rc = -ENOMEM;
		goto free_exit;
	}

	nci_set_parent_dev(drv->ndev, &pdev->dev);
	nci_set_drvdata(drv->ndev, drv);

	rc = nci_register_device(drv->ndev);
	if (rc < 0) {
		nfc_dev_err(&pdev->dev, "nci_register_device failed %d", rc);
		goto free_dev_exit;
	}

	dev_set_drvdata(&pdev->dev, drv);

	goto exit;

free_dev_exit:
	nci_free_device(drv->ndev);

free_exit:
	kfree(drv);

exit:
	return rc;
}

static int nfcwilink_remove(struct platform_device *pdev)
{
	struct nfcwilink *drv = dev_get_drvdata(&pdev->dev);
	struct nci_dev *ndev;

	nfc_dev_dbg(&pdev->dev, "remove entry");

	if (!drv)
		return -EFAULT;

	ndev = drv->ndev;

	nci_unregister_device(ndev);
	nci_free_device(ndev);

	kfree(drv);

	dev_set_drvdata(&pdev->dev, NULL);

	return 0;
}

static struct platform_driver nfcwilink_driver = {
	.probe = nfcwilink_probe,
	.remove = nfcwilink_remove,
	.driver = {
		.name = "nfcwilink",
		.owner = THIS_MODULE,
	},
};

/* ------- Module Init/Exit interfaces ------ */
static int __init nfcwilink_init(void)
{
	printk(KERN_INFO "NFC Driver for TI WiLink");

	return platform_driver_register(&nfcwilink_driver);
}

static void __exit nfcwilink_exit(void)
{
	platform_driver_unregister(&nfcwilink_driver);
}

module_init(nfcwilink_init);
module_exit(nfcwilink_exit);

/* ------ Module Info ------ */

MODULE_AUTHOR("Ilan Elias <ilane@ti.com>");
MODULE_DESCRIPTION("NFC Driver for TI Shared Transport");
MODULE_LICENSE("GPL");