drivers/nfc/pn533/uart.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Driver for NXP PN532 NFC Chip - UART transport layer
  *
  * Copyright (C) 2018 Lemonage Software GmbH
  * Author: Lars Pöschel <poeschel@lemonage.de>
  * All rights reserved.
  */

 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/nfc.h>
 #include <linux/netdevice.h>
 #include <linux/of.h>
 #include <linux/serdev.h>
 #include "pn533.h"

 #define PN532_UART_SKB_BUFF_LEN	(PN533_CMD_DATAEXCH_DATA_MAXLEN * 2)

 enum send_wakeup {
 	PN532_SEND_NO_WAKEUP = 0,
 	PN532_SEND_WAKEUP,
 	PN532_SEND_LAST_WAKEUP,
 };


 struct pn532_uart_phy {
 	struct serdev_device *serdev;
 	struct sk_buff *recv_skb;
 	struct pn533 *priv;
 	/*
 	 * send_wakeup variable is used to control if we need to send a wakeup
 	 * request to the pn532 chip prior to our actual command. There is a
 	 * little propability of a race condition. We decided to not mutex the
 	 * variable as the worst that could happen is, that we send a wakeup
 	 * to the chip that is already awake. This does not hurt. It is a
 	 * no-op to the chip.
 	 */
 	enum send_wakeup send_wakeup;
 	struct timer_list cmd_timeout;
 	struct sk_buff *cur_out_buf;
 };

 static int pn532_uart_send_frame(struct pn533 *dev,
 				struct sk_buff *out)
 {
 	/* wakeup sequence and dummy bytes for waiting time */
 	static const u8 wakeup[] = {
 		0x55, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 		0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
 	struct pn532_uart_phy *pn532 = dev->phy;
 	int err;

 	print_hex_dump_debug("PN532_uart TX: ", DUMP_PREFIX_NONE, 16, 1,
 			     out->data, out->len, false);

 	pn532->cur_out_buf = out;
 	if (pn532->send_wakeup) {
 		err = serdev_device_write(pn532->serdev,
 				wakeup, sizeof(wakeup),
 				MAX_SCHEDULE_TIMEOUT);
 		if (err < 0)
 			return err;
 	}

 	if (pn532->send_wakeup == PN532_SEND_LAST_WAKEUP)
 		pn532->send_wakeup = PN532_SEND_NO_WAKEUP;

 	err = serdev_device_write(pn532->serdev, out->data, out->len,
 			MAX_SCHEDULE_TIMEOUT);
 	if (err < 0)
 		return err;

 	mod_timer(&pn532->cmd_timeout, HZ / 40 + jiffies);
 	return 0;
 }

 static int pn532_uart_send_ack(struct pn533 *dev, gfp_t flags)
 {
 	/* spec 7.1.1.3:  Preamble, SoPC (2), ACK Code (2), Postamble */
 	static const u8 ack[PN533_STD_FRAME_ACK_SIZE] = {
 			0x00, 0x00, 0xff, 0x00, 0xff, 0x00};
 	struct pn532_uart_phy *pn532 = dev->phy;
 	int err;

 	err = serdev_device_write(pn532->serdev, ack, sizeof(ack),
 			MAX_SCHEDULE_TIMEOUT);
 	if (err < 0)
 		return err;

 	return 0;
 }

 static void pn532_uart_abort_cmd(struct pn533 *dev, gfp_t flags)
 {
 	/* An ack will cancel the last issued command */
 	pn532_uart_send_ack(dev, flags);
 	/* schedule cmd_complete_work to finish current command execution */
 	pn533_recv_frame(dev, NULL, -ENOENT);
 }

 static int pn532_dev_up(struct pn533 *dev)
 {
 	struct pn532_uart_phy *pn532 = dev->phy;
 	int ret = 0;

 	ret = serdev_device_open(pn532->serdev);
 	if (ret)
 		return ret;

 	pn532->send_wakeup = PN532_SEND_LAST_WAKEUP;
 	return ret;
 }

 static int pn532_dev_down(struct pn533 *dev)
 {
 	struct pn532_uart_phy *pn532 = dev->phy;

 	serdev_device_close(pn532->serdev);
 	pn532->send_wakeup = PN532_SEND_WAKEUP;

 	return 0;
 }

 static struct pn533_phy_ops uart_phy_ops = {
 	.send_frame = pn532_uart_send_frame,
 	.send_ack = pn532_uart_send_ack,
 	.abort_cmd = pn532_uart_abort_cmd,
 	.dev_up = pn532_dev_up,
 	.dev_down = pn532_dev_down,
 };

 static void pn532_cmd_timeout(struct timer_list *t)
 {
 	struct pn532_uart_phy *dev = from_timer(dev, t, cmd_timeout);

 	pn532_uart_send_frame(dev->priv, dev->cur_out_buf);
 }

 /*
  * scans the buffer if it contains a pn532 frame. It is not checked if the
  * frame is really valid. This is later done with pn533_rx_frame_is_valid.
  * This is useful for malformed or errornous transmitted frames. Adjusts the
  * bufferposition where the frame starts, since pn533_recv_frame expects a
  * well formed frame.
  */
 static int pn532_uart_rx_is_frame(struct sk_buff *skb)
 {
 	struct pn533_std_frame *std;
 	struct pn533_ext_frame *ext;
 	u16 frame_len;
 	int i;

 	for (i = 0; i + PN533_STD_FRAME_ACK_SIZE <= skb->len; i++) {
 		std = (struct pn533_std_frame *)&skb->data[i];
 		/* search start code */
 		if (std->start_frame != cpu_to_be16(PN533_STD_FRAME_SOF))
 			continue;

 		/* frame type */
 		switch (std->datalen) {
 		case PN533_FRAME_DATALEN_ACK:
 			if (std->datalen_checksum == 0xff) {
 				skb_pull(skb, i);
 				return 1;
 			}

 			break;
 		case PN533_FRAME_DATALEN_ERROR:
 			if ((std->datalen_checksum == 0xff) &&
 					(skb->len >=
 					 PN533_STD_ERROR_FRAME_SIZE)) {
 				skb_pull(skb, i);
 				return 1;
 			}

 			break;
 		case PN533_FRAME_DATALEN_EXTENDED:
 			ext = (struct pn533_ext_frame *)&skb->data[i];
 			frame_len = be16_to_cpu(ext->datalen);
 			if (skb->len >= frame_len +
 					sizeof(struct pn533_ext_frame) +
 					2 /* CKS + Postamble */) {
 				skb_pull(skb, i);
 				return 1;
 			}

 			break;
 		default: /* normal information frame */
 			frame_len = std->datalen;
 			if (skb->len >= frame_len +
 					sizeof(struct pn533_std_frame) +
 					2 /* CKS + Postamble */) {
 				skb_pull(skb, i);
 				return 1;
 			}

 			break;
 		}
 	}

 	return 0;
 }

 static int pn532_receive_buf(struct serdev_device *serdev,
 		const unsigned char *data, size_t count)
 {
 	struct pn532_uart_phy *dev = serdev_device_get_drvdata(serdev);
 	size_t i;

 	del_timer(&dev->cmd_timeout);
 	for (i = 0; i < count; i++) {
 		skb_put_u8(dev->recv_skb, *data++);
 		if (!pn532_uart_rx_is_frame(dev->recv_skb))
 			continue;

 		pn533_recv_frame(dev->priv, dev->recv_skb, 0);
 		dev->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
 		if (!dev->recv_skb)
 			return 0;
 	}

 	return i;
 }

 static struct serdev_device_ops pn532_serdev_ops = {
 	.receive_buf = pn532_receive_buf,
 	.write_wakeup = serdev_device_write_wakeup,
 };

 static const struct of_device_id pn532_uart_of_match[] = {
 	{ .compatible = "nxp,pn532", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, pn532_uart_of_match);

 static int pn532_uart_probe(struct serdev_device *serdev)
 {
 	struct pn532_uart_phy *pn532;
 	struct pn533 *priv;
 	int err;

 	err = -ENOMEM;
 	pn532 = kzalloc(sizeof(*pn532), GFP_KERNEL);
 	if (!pn532)
 		goto err_exit;

 	pn532->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
 	if (!pn532->recv_skb)
 		goto err_free;

 	pn532->serdev = serdev;
 	serdev_device_set_drvdata(serdev, pn532);
 	serdev_device_set_client_ops(serdev, &pn532_serdev_ops);
 	err = serdev_device_open(serdev);
 	if (err) {
 		dev_err(&serdev->dev, "Unable to open device\n");
 		goto err_skb;
 	}

 	err = serdev_device_set_baudrate(serdev, 115200);
 	if (err != 115200) {
 		err = -EINVAL;
 		goto err_serdev;
 	}

 	serdev_device_set_flow_control(serdev, false);
 	pn532->send_wakeup = PN532_SEND_WAKEUP;
 	timer_setup(&pn532->cmd_timeout, pn532_cmd_timeout, 0);
 	priv = pn53x_common_init(PN533_DEVICE_PN532_AUTOPOLL,
 				     PN533_PROTO_REQ_ACK_RESP,
 				     pn532, &uart_phy_ops, NULL,
 				     &pn532->serdev->dev);
 	if (IS_ERR(priv)) {
 		err = PTR_ERR(priv);
 		goto err_serdev;
 	}

 	pn532->priv = priv;
 	err = pn533_finalize_setup(pn532->priv);
 	if (err)
 		goto err_clean;

 	serdev_device_close(serdev);
 	err = pn53x_register_nfc(priv, PN533_NO_TYPE_B_PROTOCOLS, &serdev->dev);
 	if (err) {
 		pn53x_common_clean(pn532->priv);
 		goto err_skb;
 	}

 	return err;

 err_clean:
 	pn53x_common_clean(pn532->priv);
 err_serdev:
 	serdev_device_close(serdev);
 err_skb:
 	kfree_skb(pn532->recv_skb);
 err_free:
 	kfree(pn532);
 err_exit:
 	return err;
 }

 static void pn532_uart_remove(struct serdev_device *serdev)
 {
 	struct pn532_uart_phy *pn532 = serdev_device_get_drvdata(serdev);

 	pn53x_unregister_nfc(pn532->priv);
 	serdev_device_close(serdev);
 	pn53x_common_clean(pn532->priv);
 	kfree_skb(pn532->recv_skb);
 	kfree(pn532);
 }

 static struct serdev_device_driver pn532_uart_driver = {
 	.probe = pn532_uart_probe,
 	.remove = pn532_uart_remove,
 	.driver = {
 		.name = "pn532_uart",
 		.of_match_table = pn532_uart_of_match,
 	},
 };

 module_serdev_device_driver(pn532_uart_driver);

 MODULE_AUTHOR("Lars Pöschel <poeschel@lemonage.de>");
 MODULE_DESCRIPTION("PN532 UART driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Driver for NXP PN532 NFC Chip - UART transport layer
	*
	* Copyright (C) 2018 Lemonage Software GmbH
	* Author: Lars Pöschel <poeschel@lemonage.de>
	* All rights reserved.
	*/

	#include <linux/device.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/nfc.h>
	#include <linux/netdevice.h>
	#include <linux/of.h>
	#include <linux/serdev.h>
	#include "pn533.h"

	#define PN532_UART_SKB_BUFF_LEN (PN533_CMD_DATAEXCH_DATA_MAXLEN * 2)

	enum send_wakeup {
	PN532_SEND_NO_WAKEUP = 0,
	PN532_SEND_WAKEUP,
	PN532_SEND_LAST_WAKEUP,
	};


	struct pn532_uart_phy {
	struct serdev_device *serdev;
	struct sk_buff *recv_skb;
	struct pn533 *priv;
	/*
	* send_wakeup variable is used to control if we need to send a wakeup
	* request to the pn532 chip prior to our actual command. There is a
	* little propability of a race condition. We decided to not mutex the
	* variable as the worst that could happen is, that we send a wakeup
	* to the chip that is already awake. This does not hurt. It is a
	* no-op to the chip.
	*/
	enum send_wakeup send_wakeup;
	struct timer_list cmd_timeout;
	struct sk_buff *cur_out_buf;
	};

	static int pn532_uart_send_frame(struct pn533 *dev,
	struct sk_buff *out)
	{
	/* wakeup sequence and dummy bytes for waiting time */
	static const u8 wakeup[] = {
	0x55, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
	struct pn532_uart_phy *pn532 = dev->phy;
	int err;

	print_hex_dump_debug("PN532_uart TX: ", DUMP_PREFIX_NONE, 16, 1,
	out->data, out->len, false);

	pn532->cur_out_buf = out;
	if (pn532->send_wakeup) {
	err = serdev_device_write(pn532->serdev,
	wakeup, sizeof(wakeup),
	MAX_SCHEDULE_TIMEOUT);
	if (err < 0)
	return err;
	}

	if (pn532->send_wakeup == PN532_SEND_LAST_WAKEUP)
	pn532->send_wakeup = PN532_SEND_NO_WAKEUP;

	err = serdev_device_write(pn532->serdev, out->data, out->len,
	MAX_SCHEDULE_TIMEOUT);
	if (err < 0)
	return err;

	mod_timer(&pn532->cmd_timeout, HZ / 40 + jiffies);
	return 0;
	}

	static int pn532_uart_send_ack(struct pn533 *dev, gfp_t flags)
	{
	/* spec 7.1.1.3: Preamble, SoPC (2), ACK Code (2), Postamble */
	static const u8 ack[PN533_STD_FRAME_ACK_SIZE] = {
	0x00, 0x00, 0xff, 0x00, 0xff, 0x00};
	struct pn532_uart_phy *pn532 = dev->phy;
	int err;

	err = serdev_device_write(pn532->serdev, ack, sizeof(ack),
	MAX_SCHEDULE_TIMEOUT);
	if (err < 0)
	return err;

	return 0;
	}

	static void pn532_uart_abort_cmd(struct pn533 *dev, gfp_t flags)
	{
	/* An ack will cancel the last issued command */
	pn532_uart_send_ack(dev, flags);
	/* schedule cmd_complete_work to finish current command execution */
	pn533_recv_frame(dev, NULL, -ENOENT);
	}

	static int pn532_dev_up(struct pn533 *dev)
	{
	struct pn532_uart_phy *pn532 = dev->phy;
	int ret = 0;

	ret = serdev_device_open(pn532->serdev);
	if (ret)
	return ret;

	pn532->send_wakeup = PN532_SEND_LAST_WAKEUP;
	return ret;
	}

	static int pn532_dev_down(struct pn533 *dev)
	{
	struct pn532_uart_phy *pn532 = dev->phy;

	serdev_device_close(pn532->serdev);
	pn532->send_wakeup = PN532_SEND_WAKEUP;

	return 0;
	}

	static struct pn533_phy_ops uart_phy_ops = {
	.send_frame = pn532_uart_send_frame,
	.send_ack = pn532_uart_send_ack,
	.abort_cmd = pn532_uart_abort_cmd,
	.dev_up = pn532_dev_up,
	.dev_down = pn532_dev_down,
	};

	static void pn532_cmd_timeout(struct timer_list *t)
	{
	struct pn532_uart_phy *dev = from_timer(dev, t, cmd_timeout);

	pn532_uart_send_frame(dev->priv, dev->cur_out_buf);
	}

	/*
	* scans the buffer if it contains a pn532 frame. It is not checked if the
	* frame is really valid. This is later done with pn533_rx_frame_is_valid.
	* This is useful for malformed or errornous transmitted frames. Adjusts the
	* bufferposition where the frame starts, since pn533_recv_frame expects a
	* well formed frame.
	*/
	static int pn532_uart_rx_is_frame(struct sk_buff *skb)
	{
	struct pn533_std_frame *std;
	struct pn533_ext_frame *ext;
	u16 frame_len;
	int i;

	for (i = 0; i + PN533_STD_FRAME_ACK_SIZE <= skb->len; i++) {
	std = (struct pn533_std_frame *)&skb->data[i];
	/* search start code */
	if (std->start_frame != cpu_to_be16(PN533_STD_FRAME_SOF))
	continue;

	/* frame type */
	switch (std->datalen) {
	case PN533_FRAME_DATALEN_ACK:
	if (std->datalen_checksum == 0xff) {
	skb_pull(skb, i);
	return 1;
	}

	break;
	case PN533_FRAME_DATALEN_ERROR:
	if ((std->datalen_checksum == 0xff) &&
	(skb->len >=
	PN533_STD_ERROR_FRAME_SIZE)) {
	skb_pull(skb, i);
	return 1;
	}

	break;
	case PN533_FRAME_DATALEN_EXTENDED:
	ext = (struct pn533_ext_frame *)&skb->data[i];
	frame_len = be16_to_cpu(ext->datalen);
	if (skb->len >= frame_len +
	sizeof(struct pn533_ext_frame) +
	2 /* CKS + Postamble */) {
	skb_pull(skb, i);
	return 1;
	}

	break;
	default: /* normal information frame */
	frame_len = std->datalen;
	if (skb->len >= frame_len +
	sizeof(struct pn533_std_frame) +
	2 /* CKS + Postamble */) {
	skb_pull(skb, i);
	return 1;
	}

	break;
	}
	}

	return 0;
	}

	static int pn532_receive_buf(struct serdev_device *serdev,
	const unsigned char *data, size_t count)
	{
	struct pn532_uart_phy *dev = serdev_device_get_drvdata(serdev);
	size_t i;

	del_timer(&dev->cmd_timeout);
	for (i = 0; i < count; i++) {
	skb_put_u8(dev->recv_skb, *data++);
	if (!pn532_uart_rx_is_frame(dev->recv_skb))
	continue;

	pn533_recv_frame(dev->priv, dev->recv_skb, 0);
	dev->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
	if (!dev->recv_skb)
	return 0;
	}

	return i;
	}

	static struct serdev_device_ops pn532_serdev_ops = {
	.receive_buf = pn532_receive_buf,
	.write_wakeup = serdev_device_write_wakeup,
	};

	static const struct of_device_id pn532_uart_of_match[] = {
	{ .compatible = "nxp,pn532", },
	{},
	};
	MODULE_DEVICE_TABLE(of, pn532_uart_of_match);

	static int pn532_uart_probe(struct serdev_device *serdev)
	{
	struct pn532_uart_phy *pn532;
	struct pn533 *priv;
	int err;

	err = -ENOMEM;
	pn532 = kzalloc(sizeof(*pn532), GFP_KERNEL);
	if (!pn532)
	goto err_exit;

	pn532->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
	if (!pn532->recv_skb)
	goto err_free;

	pn532->serdev = serdev;
	serdev_device_set_drvdata(serdev, pn532);
	serdev_device_set_client_ops(serdev, &pn532_serdev_ops);
	err = serdev_device_open(serdev);
	if (err) {
	dev_err(&serdev->dev, "Unable to open device\n");
	goto err_skb;
	}

	err = serdev_device_set_baudrate(serdev, 115200);
	if (err != 115200) {
	err = -EINVAL;
	goto err_serdev;
	}

	serdev_device_set_flow_control(serdev, false);
	pn532->send_wakeup = PN532_SEND_WAKEUP;
	timer_setup(&pn532->cmd_timeout, pn532_cmd_timeout, 0);
	priv = pn53x_common_init(PN533_DEVICE_PN532_AUTOPOLL,
	PN533_PROTO_REQ_ACK_RESP,
	pn532, &uart_phy_ops, NULL,
	&pn532->serdev->dev);
	if (IS_ERR(priv)) {
	err = PTR_ERR(priv);
	goto err_serdev;
	}

	pn532->priv = priv;
	err = pn533_finalize_setup(pn532->priv);
	if (err)
	goto err_clean;

	serdev_device_close(serdev);
	err = pn53x_register_nfc(priv, PN533_NO_TYPE_B_PROTOCOLS, &serdev->dev);
	if (err) {
	pn53x_common_clean(pn532->priv);
	goto err_skb;
	}

	return err;

	err_clean:
	pn53x_common_clean(pn532->priv);
	err_serdev:
	serdev_device_close(serdev);
	err_skb:
	kfree_skb(pn532->recv_skb);
	err_free:
	kfree(pn532);
	err_exit:
	return err;
	}

	static void pn532_uart_remove(struct serdev_device *serdev)
	{
	struct pn532_uart_phy *pn532 = serdev_device_get_drvdata(serdev);

	pn53x_unregister_nfc(pn532->priv);
	serdev_device_close(serdev);
	pn53x_common_clean(pn532->priv);
	kfree_skb(pn532->recv_skb);
	kfree(pn532);
	}

	static struct serdev_device_driver pn532_uart_driver = {
	.probe = pn532_uart_probe,
	.remove = pn532_uart_remove,
	.driver = {
	.name = "pn532_uart",
	.of_match_table = pn532_uart_of_match,
	},
	};

	module_serdev_device_driver(pn532_uart_driver);

	MODULE_AUTHOR("Lars Pöschel <poeschel@lemonage.de>");
	MODULE_DESCRIPTION("PN532 UART driver");
	MODULE_LICENSE("GPL");