alistair23-linux/drivers/nfc/pn533/i2c.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for NXP PN533 NFC Chip - I2C transport layer
 *
 * Copyright (C) 2011 Instituto Nokia de Tecnologia
 * Copyright (C) 2012-2013 Tieto Poland
 * Copyright (C) 2016 HALE electronic
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/nfc.h>
#include <linux/netdevice.h>
#include <linux/interrupt.h>
#include <net/nfc/nfc.h>
#include "pn533.h"

#define VERSION "0.1"

#define PN533_I2C_DRIVER_NAME "pn533_i2c"

struct pn533_i2c_phy {
	struct i2c_client *i2c_dev;
	struct pn533 *priv;

	bool aborted;

	int hard_fault;		/*
				 * < 0 if hardware error occurred (e.g. i2c err)
				 * and prevents normal operation.
				 */
};

static int pn533_i2c_send_ack(struct pn533 *dev, gfp_t flags)
{
	struct pn533_i2c_phy *phy = dev->phy;
	struct i2c_client *client = phy->i2c_dev;
	static const u8 ack[6] = {0x00, 0x00, 0xff, 0x00, 0xff, 0x00};
	/* spec 6.2.1.3:  Preamble, SoPC (2), ACK Code (2), Postamble */
	int rc;

	rc = i2c_master_send(client, ack, 6);

	return rc;
}

static int pn533_i2c_send_frame(struct pn533 *dev,
				struct sk_buff *out)
{
	struct pn533_i2c_phy *phy = dev->phy;
	struct i2c_client *client = phy->i2c_dev;
	int rc;

	if (phy->hard_fault != 0)
		return phy->hard_fault;

	if (phy->priv == NULL)
		phy->priv = dev;

	phy->aborted = false;

	print_hex_dump_debug("PN533_i2c TX: ", DUMP_PREFIX_NONE, 16, 1,
			     out->data, out->len, false);

	rc = i2c_master_send(client, out->data, out->len);

	if (rc == -EREMOTEIO) { /* Retry, chip was in power down */
		usleep_range(6000, 10000);
		rc = i2c_master_send(client, out->data, out->len);
	}

	if (rc >= 0) {
		if (rc != out->len)
			rc = -EREMOTEIO;
		else
			rc = 0;
	}

	return rc;
}

static void pn533_i2c_abort_cmd(struct pn533 *dev, gfp_t flags)
{
	struct pn533_i2c_phy *phy = dev->phy;

	phy->aborted = true;

	/* An ack will cancel the last issued command */
	pn533_i2c_send_ack(dev, flags);

	/* schedule cmd_complete_work to finish current command execution */
	pn533_recv_frame(phy->priv, NULL, -ENOENT);
}

static int pn533_i2c_read(struct pn533_i2c_phy *phy, struct sk_buff **skb)
{
	struct i2c_client *client = phy->i2c_dev;
	int len = PN533_EXT_FRAME_HEADER_LEN +
		  PN533_STD_FRAME_MAX_PAYLOAD_LEN +
		  PN533_STD_FRAME_TAIL_LEN + 1;
	int r;

	*skb = alloc_skb(len, GFP_KERNEL);
	if (*skb == NULL)
		return -ENOMEM;

	r = i2c_master_recv(client, skb_put(*skb, len), len);
	if (r != len) {
		nfc_err(&client->dev, "cannot read. r=%d len=%d\n", r, len);
		kfree_skb(*skb);
		return -EREMOTEIO;
	}

	if (!((*skb)->data[0] & 0x01)) {
		nfc_err(&client->dev, "READY flag not set");
		kfree_skb(*skb);
		return -EBUSY;
	}

	/* remove READY byte */
	skb_pull(*skb, 1);
	/* trim to frame size */
	skb_trim(*skb, phy->priv->ops->rx_frame_size((*skb)->data));

	return 0;
}

static irqreturn_t pn533_i2c_irq_thread_fn(int irq, void *data)
{
	struct pn533_i2c_phy *phy = data;
	struct i2c_client *client;
	struct sk_buff *skb = NULL;
	int r;

	if (!phy || irq != phy->i2c_dev->irq) {
		WARN_ON_ONCE(1);
		return IRQ_NONE;
	}

	client = phy->i2c_dev;
	dev_dbg(&client->dev, "IRQ\n");

	if (phy->hard_fault != 0)
		return IRQ_HANDLED;

	r = pn533_i2c_read(phy, &skb);
	if (r == -EREMOTEIO) {
		phy->hard_fault = r;

		pn533_recv_frame(phy->priv, NULL, -EREMOTEIO);

		return IRQ_HANDLED;
	} else if ((r == -ENOMEM) || (r == -EBADMSG) || (r == -EBUSY)) {
		return IRQ_HANDLED;
	}

	if (!phy->aborted)
		pn533_recv_frame(phy->priv, skb, 0);

	return IRQ_HANDLED;
}

static struct pn533_phy_ops i2c_phy_ops = {
	.send_frame = pn533_i2c_send_frame,
	.send_ack = pn533_i2c_send_ack,
	.abort_cmd = pn533_i2c_abort_cmd,
};


static int pn533_i2c_probe(struct i2c_client *client,
			       const struct i2c_device_id *id)
{
	struct pn533_i2c_phy *phy;
	struct pn533 *priv;
	int r = 0;

	dev_dbg(&client->dev, "%s\n", __func__);
	dev_dbg(&client->dev, "IRQ: %d\n", client->irq);

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
		nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
		return -ENODEV;
	}

	phy = devm_kzalloc(&client->dev, sizeof(struct pn533_i2c_phy),
			   GFP_KERNEL);
	if (!phy)
		return -ENOMEM;

	phy->i2c_dev = client;
	i2c_set_clientdata(client, phy);

	priv = pn533_register_device(PN533_DEVICE_PN532,
				     PN533_NO_TYPE_B_PROTOCOLS,
				     PN533_PROTO_REQ_ACK_RESP,
				     phy, &i2c_phy_ops, NULL,
				     &phy->i2c_dev->dev,
				     &client->dev);

	if (IS_ERR(priv)) {
		r = PTR_ERR(priv);
		return r;
	}

	phy->priv = priv;

	r = request_threaded_irq(client->irq, NULL, pn533_i2c_irq_thread_fn,
				IRQF_TRIGGER_FALLING |
				IRQF_SHARED | IRQF_ONESHOT,
				PN533_I2C_DRIVER_NAME, phy);
	if (r < 0) {
		nfc_err(&client->dev, "Unable to register IRQ handler\n");
		goto irq_rqst_err;
	}

	r = pn533_finalize_setup(priv);
	if (r)
		goto fn_setup_err;

	return 0;

fn_setup_err:
	free_irq(client->irq, phy);

irq_rqst_err:
	pn533_unregister_device(phy->priv);

	return r;
}

static int pn533_i2c_remove(struct i2c_client *client)
{
	struct pn533_i2c_phy *phy = i2c_get_clientdata(client);

	dev_dbg(&client->dev, "%s\n", __func__);

	free_irq(client->irq, phy);

	pn533_unregister_device(phy->priv);

	return 0;
}

static const struct of_device_id of_pn533_i2c_match[] = {
	{ .compatible = "nxp,pn533-i2c", },
	{ .compatible = "nxp,pn532-i2c", },
	{},
};
MODULE_DEVICE_TABLE(of, of_pn533_i2c_match);

static const struct i2c_device_id pn533_i2c_id_table[] = {
	{ PN533_I2C_DRIVER_NAME, 0 },
	{}
};
MODULE_DEVICE_TABLE(i2c, pn533_i2c_id_table);

static struct i2c_driver pn533_i2c_driver = {
	.driver = {
		   .name = PN533_I2C_DRIVER_NAME,
		   .owner = THIS_MODULE,
		   .of_match_table = of_match_ptr(of_pn533_i2c_match),
		  },
	.probe = pn533_i2c_probe,
	.id_table = pn533_i2c_id_table,
	.remove = pn533_i2c_remove,
};

module_i2c_driver(pn533_i2c_driver);

MODULE_AUTHOR("Michael Thalmeier <michael.thalmeier@hale.at>");
MODULE_DESCRIPTION("PN533 I2C driver ver " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");