NFC: Add driver support for NTAG

Qualcomm Technologies, Inc NTx NTAG device

Near Field Communication wireless tag integrated circuit device(NTAG) is compliant

with NFC Forum Type 2 Tag specification.

Required properties:

- compatible: "qcom,nq-ntag"

- reg: i2c slave address.

- pinctrl-names, pinctrl-0, pinctrl-1: references to our pinctrl settings

- qcom,nq-ntagfd : specific gpio for field detect interrupt.

Example:

	nq-ntag@55 {

		compatible = "qcom,nq-ntag";

		reg = <0x55>;

		qcom,nq-ntagfd = <&tlmm 22 0x00>;

		interrupt-parent = <&tlmm>;

		interrupts = <22 0>;

		interrupt-names = "ntag_fd";

		pinctrl-names = "ntag_active","ntag_suspend";

		pinctrl-0 = <&ntag_int_active>;

		pinctrl-1 = <&ntag_int_suspend>;

	};

          This enables the NFC driver for NQx based devices.

          This is for i2c connected version. NCI protocol logic

          resides in the usermode and it has no other NFC dependencies.

config NTAG_NQ

	tristate "QTI NTAG Driver for NTAG communication"

	depends on I2C

	help

          This enables NTAG driver for NTx based devices.

          NTAG is NFC tags that combine passive NFC interface with contact i2c interface.

          This is for i2c connected version.

obj-$(CONFIG_NFC_S3FWRN5)	+= s3fwrn5/

obj-$(CONFIG_NFC_ST95HF)	+= st95hf/

obj-$(CONFIG_NFC_NQ)		+= nq-nci.o

obj-$(CONFIG_NTAG_NQ)		+= nq-ntag.o

/* Copyright (c) 2018, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only 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.

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/irq.h>

#include <linux/fs.h>

#include <linux/interrupt.h>

#include <linux/slab.h>

#include <linux/gpio.h>

#include <linux/spinlock.h>

#include <linux/of_gpio.h>

#include <linux/of_device.h>

#include <linux/uaccess.h>

#include <linux/wait.h>

#include <linux/ioctl.h>

#include <linux/cdev.h>

#include <linux/i2c.h>

#include "nq-ntag.h"

struct nqntag_platform_data {

	unsigned int ntagfd_gpio;

};

const static struct of_device_id msm_match_table[] = {

	{.compatible = "qcom,nq-ntag"},

	{},

};

MODULE_DEVICE_TABLE(of, msm_match_table);

struct nqntag_dev {

	wait_queue_head_t fd_wq;

	struct mutex fd_mutex;

	struct i2c_client *client;

	dev_t devno;

	struct class *nqntag_class;

	struct device *nqntag_device;

	struct cdev c_dev;

	bool irq_enabled;

	bool irq_wake_up;

	spinlock_t irq_enabled_lock;

	char offset;

	unsigned int ntagfd_gpio;

	enum of_gpio_flags fdflag;

	/* read buffer*/

	size_t kbuflen;

	u8 *kbuf;

};

/**

 * nqntag_irq_state()

 *

 * Based on state enable/disable FD interrupt

 *

 * Return: void

 */

static void nqntag_irq_state(struct nqntag_dev *nqntag_dev, unsigned int state)

{

	unsigned long flags;

	spin_lock_irqsave(&nqntag_dev->irq_enabled_lock, flags);

	if (state == FD_DISABLE) {

		if (nqntag_dev->irq_enabled) {

			disable_irq_nosync(nqntag_dev->client->irq);

			nqntag_dev->irq_enabled = false;

		}

	} else {

		if (!nqntag_dev->irq_enabled) {

			nqntag_dev->irq_enabled = true;

			enable_irq(nqntag_dev->client->irq);

		}

	}

	spin_unlock_irqrestore(&nqntag_dev->irq_enabled_lock, flags);

}

static irqreturn_t nqntag_dev_irq_handler(int irq, void *dev_id)

{

	struct nqntag_dev *nqntag_dev = dev_id;

	if (device_may_wakeup(&nqntag_dev->client->dev))

		pm_wakeup_event(&nqntag_dev->client->dev, WAKEUP_SRC_TIMEOUT);

	nqntag_irq_state(nqntag_dev, FD_DISABLE);

	wake_up(&nqntag_dev->fd_wq);

	return IRQ_HANDLED;

}

static ssize_t ntag_read(struct file *file, char __user *buf, size_t count,

		loff_t *offset)

{

	char *readdata;

	int ret = 0;

	size_t tmpcount = 1;

	struct nqntag_dev *nqntag_dev;

	char *bufaddr = NULL;

	if (!file || !file->private_data)

		return -ENODATA;

	nqntag_dev = file->private_data;

	if (nqntag_dev->offset < NTAG_MIN_OFFSET ||

		nqntag_dev->offset >= NTAG_USER_MEM_SPACE_MAX_OFFSET) {

		return -EAGAIN;

	}

	bufaddr = &nqntag_dev->offset;

	ret = i2c_master_send(nqntag_dev->client, bufaddr, tmpcount);

	if (ret < 0) {

		dev_err(&nqntag_dev->client->dev,

			"%s: failed to write %d\n", __func__, ret);

		return -EIO;

	}

	/* count+1 to store NULL byte */

	readdata = kzalloc(count + 1, GFP_KERNEL);

	if (readdata == NULL)

		return -ENOMEM;

	ret = i2c_master_recv(nqntag_dev->client, readdata, count);

	if (ret >= 0)

		ret = copy_to_user(buf, readdata, count) ? -EFAULT : ret;

	kfree(readdata);

	return ret;

}

static ssize_t ntag_write(struct file *file, const char __user *buf,

		size_t count, loff_t *offset)

{

	int ret = 0;

	char *writedata;

	struct nqntag_dev *nqntag_dev;

	if (!file || !file->private_data)

		return -ENODATA;

	nqntag_dev = file->private_data;

	if (nqntag_dev->offset < NTAG_MIN_OFFSET ||

		nqntag_dev->offset >= NTAG_USER_MEM_SPACE_MAX_OFFSET) {

		return -EAGAIN;

	}

	/* count+2 to store Offset and NULL byte */

	writedata = kzalloc(count + 2, GFP_KERNEL);

	if (writedata == NULL)

		return -ENOMEM;

	writedata[0] = nqntag_dev->offset;

	if (copy_from_user(&writedata[1], buf, count)) {

		dev_err(&nqntag_dev->client->dev, "Failed to copy from user\n");

		kfree(writedata);

		return -EFAULT;

	}

	ret = i2c_master_send(nqntag_dev->client, writedata, count + 1);

	if (ret != (count + 1)) {

		dev_err(&nqntag_dev->client->dev,

			"%s: failed to write %d\n", __func__, ret);

		kfree(writedata);

		return -EIO;

	}

	kfree(writedata);

	return count;

}

static int ntag_open(struct inode *inode, struct file *filp)

{

	struct nqntag_dev *nqntag_dev = container_of(inode->i_cdev,

				struct nqntag_dev, c_dev);

	filp->private_data = nqntag_dev;

	dev_dbg(&nqntag_dev->client->dev,

		 "%s: %d,%d\n", __func__, imajor(inode), iminor(inode));

	return 0;

}

/**

 * ntag_ioctl_fd_state()

 * @filp:       pointer to the file descriptor

 * @arg:        mode that we want to move to

 *

 * Device power control. Depending on the arg value, device moves to

 * different states

 * (arg = 0): FD_DISABLE

 * (arg = 1): FD_ENABLE

 *

 * Return: -ENOIOCTLCMD if arg is not supported

 */

static int ntag_ioctl_fd_state(struct file *filp, unsigned long arg)

{

	int r = 0, ret = 0;

	struct nqntag_dev *nqntag_dev = filp->private_data;

	int irq_gpio_val = 0;

	if (arg == 0) {

		/* Disabling FD interrupt */

		nqntag_irq_state(nqntag_dev, FD_DISABLE);

		return ret;

	} else if (arg == 1) {

		/* Enable FD interrupt and wait for RF field detection*/

		nqntag_irq_state(nqntag_dev, FD_ENABLE);

		mutex_lock(&nqntag_dev->fd_mutex);

		irq_gpio_val = gpio_get_value(nqntag_dev->ntagfd_gpio);

		dev_dbg(&nqntag_dev->client->dev,

			"%s: READ GPIO_VAL: %d/n", __func__, irq_gpio_val);

		if (!irq_gpio_val ^ nqntag_dev->fdflag) {

			if (filp->f_flags & O_NONBLOCK) {

				ret = -EAGAIN;

				goto err;

			}

			while (1) {

				r = 0;

				nqntag_irq_state(nqntag_dev, FD_ENABLE);

				irq_gpio_val = gpio_get_value(

						nqntag_dev->ntagfd_gpio);

				if (!irq_gpio_val ^ nqntag_dev->fdflag)

					r = wait_event_interruptible(

						nqntag_dev->fd_wq,

						!nqntag_dev->irq_enabled);

				if (r) {

					nqntag_irq_state(nqntag_dev,

							FD_DISABLE);

					ret = -EAGAIN;

					goto err;

				} else {

					break;

				}

			}

		}

	} else {

		ret = -EINVAL;

	}

err:

	mutex_unlock(&nqntag_dev->fd_mutex);

	return ret;

}

static long ntag_ioctl(struct file *pfile, unsigned int cmd,

			unsigned long arg)

{

	long r = 0;

	struct nqntag_dev *nqntag_dev;

	if (!pfile || !pfile->private_data)

		return -ENODATA;

	nqntag_dev = pfile->private_data;

	switch (cmd) {

	case NTAG_FD_STATE:

		r = ntag_ioctl_fd_state(pfile, arg);

		break;

	case NTAG_SET_OFFSET:

		nqntag_dev->offset = (char)arg;

		break;

	default:

		r = -ENOIOCTLCMD;

	}

	return r;

}

static const struct file_operations ntag_dev_fops = {

	.llseek = no_llseek,

	.read  = ntag_read,

	.write = ntag_write,

	.open = ntag_open,

	.unlocked_ioctl = ntag_ioctl,

};

static int nqntag_probe(struct i2c_client *client,

			const struct i2c_device_id *id)

{

	int r = 0, irqn = 0;

	struct nqntag_platform_data *pdata;

	struct nqntag_dev *nqntag_dev;

	enum of_gpio_flags fdflag;

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

	pdata = devm_kzalloc(&client->dev,

			sizeof(*pdata), GFP_KERNEL);

	if (!pdata) {

		r = -ENOMEM;

		goto err_probe;

	}

	pdata->ntagfd_gpio = of_get_named_gpio(

				client->dev.of_node, "qcom,nq-ntagfd", 0);

	if ((!gpio_is_valid(pdata->ntagfd_gpio))) {

		r = -EINVAL;

		goto err_probe;

	}

	r = of_get_named_gpio_flags(

		client->dev.of_node, "qcom,nq-ntagfd", 0, &fdflag);

	if (r < 0)

		goto err_probe;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {

		dev_err(&client->dev, "%s: need I2C_FUNC_I2C\n", __func__);

		r = -ENODEV;

		goto err_probe;

	}

	nqntag_dev = devm_kzalloc(&client->dev, sizeof(*nqntag_dev),

				GFP_KERNEL);

	if (nqntag_dev == NULL) {

		r = -ENOMEM;

		goto err_probe;

	}

	nqntag_dev->client = client;

	nqntag_dev->fdflag = fdflag;

	nqntag_dev->kbuflen = MAX_BUFFER_SIZE;

	nqntag_dev->kbuf = devm_kzalloc(&client->dev, MAX_BUFFER_SIZE,

					GFP_KERNEL);

	if (!nqntag_dev->kbuf) {

		r = -ENOMEM;

		goto err_probe;

	}

	r = devm_gpio_request(&client->dev, pdata->ntagfd_gpio,

			"ntagfd_gpio");

	if (r) {

		r = -ENOMEM;

		goto err_probe;

	}

	r = gpio_direction_input(pdata->ntagfd_gpio);

	if (r) {

		dev_err(&client->dev,

			"%s: unable to set direction for fd gpio [%d]\n",

			__func__, pdata->ntagfd_gpio);

		r = -EINVAL;

		goto err_probe;

	}

	irqn = gpio_to_irq(pdata->ntagfd_gpio);

	if (irqn < 0) {

		r = -EINVAL;

		goto err_probe;

	}

	client->irq = irqn;

	nqntag_dev->ntagfd_gpio = pdata->ntagfd_gpio;

	/* init mutex and wait queues */

	init_waitqueue_head(&nqntag_dev->fd_wq);

	mutex_init(&nqntag_dev->fd_mutex);

	spin_lock_init(&nqntag_dev->irq_enabled_lock);

	r = alloc_chrdev_region(&nqntag_dev->devno, 0, DEV_COUNT, DEVICE_NAME);

	if (r < 0) {

		dev_err(&client->dev,

			"%s: failed to alloc chrdev region\n", __func__);

		goto err_probe;

	}

	nqntag_dev->nqntag_class = class_create(THIS_MODULE, CLASS_NAME);

	if (IS_ERR(nqntag_dev->nqntag_class)) {

		dev_err(&client->dev,

			"%s: failed to register device class\n", __func__);

		r = -EINVAL;

		goto err_class_create;

	}

	cdev_init(&nqntag_dev->c_dev, &ntag_dev_fops);

	r = cdev_add(&nqntag_dev->c_dev, nqntag_dev->devno, DEV_COUNT);

	if (r < 0) {

		dev_err(&client->dev, "%s: failed to add cdev\n", __func__);

		goto err_cdev_add;

	}

	nqntag_dev->nqntag_device = device_create(nqntag_dev->nqntag_class,

					NULL, nqntag_dev->devno, nqntag_dev,

					DEVICE_NAME);

	if (IS_ERR(nqntag_dev->nqntag_device)) {

		dev_err(&client->dev,

			"%s: failed to create the device\n", __func__);

		r = -EINVAL;

		goto err_device_create;

	}

	 /* NTAG_INT IRQ */

	nqntag_dev->irq_enabled = true;

	r = devm_request_irq(&client->dev, client->irq, nqntag_dev_irq_handler,

			IRQ_TYPE_EDGE_FALLING, client->name, nqntag_dev);

	if (r) {

		dev_err(&client->dev, "%s: request_irq failed\n", __func__);

		goto err_request_irq_failed;

	}

	nqntag_irq_state(nqntag_dev, FD_DISABLE);

	device_init_wakeup(&client->dev, true);

	i2c_set_clientdata(client, nqntag_dev);

	nqntag_dev->irq_wake_up = false;

	return 0;

err_request_irq_failed:

	device_destroy(nqntag_dev->nqntag_class, nqntag_dev->devno);

err_device_create:

	cdev_del(&nqntag_dev->c_dev);

err_cdev_add:

	class_destroy(nqntag_dev->nqntag_class);

err_class_create:

	unregister_chrdev_region(nqntag_dev->devno, DEV_COUNT);

err_probe:

	dev_err(&client->dev, "%s: probing NQ NTAG failed ret: %d\n",

		 __func__, r);

	return r;

}

static int nqntag_remove(struct i2c_client *client)

{

	struct nqntag_dev *nqntag_dev;

	nqntag_dev = i2c_get_clientdata(client);

	device_destroy(nqntag_dev->nqntag_class, nqntag_dev->devno);

	cdev_del(&nqntag_dev->c_dev);

	class_destroy(nqntag_dev->nqntag_class);

	unregister_chrdev_region(nqntag_dev->devno, DEV_COUNT);

	return 0;

}

#ifdef CONFIG_PM

/*

 * power management

 */

static int nqntag_suspend(struct device *device)

{

	struct i2c_client *client = to_i2c_client(device);

	struct nqntag_dev *nqntag_dev = i2c_get_clientdata(client);

	nqntag_irq_state(nqntag_dev, FD_ENABLE);

	if (device_may_wakeup(&client->dev)) {

		if (!enable_irq_wake(client->irq))

			nqntag_dev->irq_wake_up = true;

	}

	return 0;

}

static int nqntag_resume(struct device *device)

{

	struct i2c_client *client = to_i2c_client(device);

	struct nqntag_dev *nqntag_dev = i2c_get_clientdata(client);

	nqntag_irq_state(nqntag_dev, FD_DISABLE);

	if (device_may_wakeup(&client->dev) && nqntag_dev->irq_wake_up) {

		if (!disable_irq_wake(client->irq))

			nqntag_dev->irq_wake_up = false;

	}

	return 0;

}

#endif /* CONFIG_PM */

static const struct i2c_device_id nqntag_id[] = {

	{"nqntag-i2c", 0},

	{},

};

static const struct dev_pm_ops ntag_pm_ops = {

	SET_SYSTEM_SLEEP_PM_OPS(nqntag_suspend,

				nqntag_resume)

};

static struct i2c_driver nqntag = {

	.id_table = nqntag_id,

	.probe = nqntag_probe,

	.remove = nqntag_remove,

	.driver = {

		.name = "nq-ntag",

		.of_match_table = msm_match_table,

		.probe_type = PROBE_PREFER_ASYNCHRONOUS,

		.pm = &ntag_pm_ops,

	},

};

static int __init nqntag_dev_init(void)

{

	return i2c_add_driver(&nqntag);

}

module_init(nqntag_dev_init);

static void __exit nqntag_dev_exit(void)

{

	i2c_del_driver(&nqntag);

}

module_exit(nqntag_dev_exit);

MODULE_DESCRIPTION("NTAG nqntag");

MODULE_LICENSE("GPL v2");

/* Copyright (c) 2018, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only 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.

 */

#ifndef __NQ_NTAG_H

#define __NQ_NTAG_H

#include <uapi/linux/nfc/ntaginfo.h>

#define DEV_COUNT   1

#define DEVICE_NAME "nq-ntag"

#define CLASS_NAME "nqntag"

#define FD_DISABLE  1

#define FD_ENABLE   0

#define MAX_BUFFER_SIZE    (320)

#define WAKEUP_SRC_TIMEOUT (2000)

#define NTAG_MIN_OFFSET     0

#define NTAG_USER_MEM_SPACE_MAX_OFFSET 56

#endif