Linux preempt-rt

Check our new training course

Real-Time Linux with PREEMPT_RT

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

// SPDX-License-Identifier: GPL-2.0-only
/*
 * I2C Link Layer for ST NCI NFC controller familly based Driver
 * Copyright (C) 2014-2015 STMicroelectronics SAS. All rights reserved.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/gpio/consumer.h>
#include <linux/acpi.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/nfc.h>
#include <linux/of.h>

#include "st-nci.h"

#define DRIVER_DESC "NCI NFC driver for ST_NCI"

/* ndlc header */
#define ST_NCI_FRAME_HEADROOM 1
#define ST_NCI_FRAME_TAILROOM 0

#define ST_NCI_I2C_MIN_SIZE 4   /* PCB(1) + NCI Packet header(3) */
#define ST_NCI_I2C_MAX_SIZE 250 /* req 4.2.1 */

#define ST_NCI_DRIVER_NAME "st_nci"
#define ST_NCI_I2C_DRIVER_NAME "st_nci_i2c"

struct st_nci_i2c_phy {
	struct i2c_client *i2c_dev;
	struct llt_ndlc *ndlc;

	bool irq_active;

	struct gpio_desc *gpiod_reset;

	struct st_nci_se_status se_status;
};

static int st_nci_i2c_enable(void *phy_id)
{
	struct st_nci_i2c_phy *phy = phy_id;

	gpiod_set_value(phy->gpiod_reset, 0);
	usleep_range(10000, 15000);
	gpiod_set_value(phy->gpiod_reset, 1);
	usleep_range(80000, 85000);

	if (phy->ndlc->powered == 0 && phy->irq_active == 0) {
		enable_irq(phy->i2c_dev->irq);
		phy->irq_active = true;
	}

	return 0;
}

static void st_nci_i2c_disable(void *phy_id)
{
	struct st_nci_i2c_phy *phy = phy_id;

	disable_irq_nosync(phy->i2c_dev->irq);
	phy->irq_active = false;
}

/*
 * Writing a frame must not return the number of written bytes.
 * It must return either zero for success, or <0 for error.
 * In addition, it must not alter the skb
 */
static int st_nci_i2c_write(void *phy_id, struct sk_buff *skb)
{
	int r;
	struct st_nci_i2c_phy *phy = phy_id;
	struct i2c_client *client = phy->i2c_dev;

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

	r = i2c_master_send(client, skb->data, skb->len);
	if (r < 0) {  /* Retry, chip was in standby */
		usleep_range(1000, 4000);
		r = i2c_master_send(client, skb->data, skb->len);
	}

	if (r >= 0) {
		if (r != skb->len)
			r = -EREMOTEIO;
		else
			r = 0;
	}

	return r;
}

/*
 * Reads an ndlc frame and returns it in a newly allocated sk_buff.
 * returns:
 * 0 : if received frame is complete
 * -EREMOTEIO : i2c read error (fatal)
 * -EBADMSG : frame was incorrect and discarded
 * -ENOMEM : cannot allocate skb, frame dropped
 */
static int st_nci_i2c_read(struct st_nci_i2c_phy *phy,
				 struct sk_buff **skb)
{
	int r;
	u8 len;
	u8 buf[ST_NCI_I2C_MAX_SIZE];
	struct i2c_client *client = phy->i2c_dev;

	r = i2c_master_recv(client, buf, ST_NCI_I2C_MIN_SIZE);
	if (r < 0) {  /* Retry, chip was in standby */
		usleep_range(1000, 4000);
		r = i2c_master_recv(client, buf, ST_NCI_I2C_MIN_SIZE);
	}

	if (r != ST_NCI_I2C_MIN_SIZE)
		return -EREMOTEIO;

	len = be16_to_cpu(*(__be16 *) (buf + 2));
	if (len > ST_NCI_I2C_MAX_SIZE) {
		nfc_err(&client->dev, "invalid frame len\n");
		return -EBADMSG;
	}

	*skb = alloc_skb(ST_NCI_I2C_MIN_SIZE + len, GFP_KERNEL);
	if (*skb == NULL)
		return -ENOMEM;

	skb_reserve(*skb, ST_NCI_I2C_MIN_SIZE);
	skb_put(*skb, ST_NCI_I2C_MIN_SIZE);
	memcpy((*skb)->data, buf, ST_NCI_I2C_MIN_SIZE);

	if (!len)
		return 0;

	r = i2c_master_recv(client, buf, len);
	if (r != len) {
		kfree_skb(*skb);
		return -EREMOTEIO;
	}

	skb_put(*skb, len);
	memcpy((*skb)->data + ST_NCI_I2C_MIN_SIZE, buf, len);

	return 0;
}

/*
 * Reads an ndlc frame from the chip.
 *
 * On ST_NCI, IRQ goes in idle state when read starts.
 */
static irqreturn_t st_nci_irq_thread_fn(int irq, void *phy_id)
{
	struct st_nci_i2c_phy *phy = phy_id;
	struct i2c_client *client;
	struct sk_buff *skb = NULL;
	int r;

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

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

	if (phy->ndlc->hard_fault)
		return IRQ_HANDLED;

	if (!phy->ndlc->powered) {
		st_nci_i2c_disable(phy);
		return IRQ_HANDLED;
	}

	r = st_nci_i2c_read(phy, &skb);
	if (r == -EREMOTEIO || r == -ENOMEM || r == -EBADMSG)
		return IRQ_HANDLED;

	ndlc_recv(phy->ndlc, skb);

	return IRQ_HANDLED;
}

static const struct nfc_phy_ops i2c_phy_ops = {
	.write = st_nci_i2c_write,
	.enable = st_nci_i2c_enable,
	.disable = st_nci_i2c_disable,
};

static const struct acpi_gpio_params reset_gpios = { 1, 0, false };

static const struct acpi_gpio_mapping acpi_st_nci_gpios[] = {
	{ "reset-gpios", &reset_gpios, 1 },
	{},
};

static int st_nci_i2c_probe(struct i2c_client *client,
				  const struct i2c_device_id *id)
{
	struct device *dev = &client->dev;
	struct st_nci_i2c_phy *phy;
	int r;

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

	phy = devm_kzalloc(dev, sizeof(struct st_nci_i2c_phy), GFP_KERNEL);
	if (!phy)
		return -ENOMEM;

	phy->i2c_dev = client;

	i2c_set_clientdata(client, phy);

	r = devm_acpi_dev_add_driver_gpios(dev, acpi_st_nci_gpios);
	if (r)
		dev_dbg(dev, "Unable to add GPIO mapping table\n");

	/* Get RESET GPIO */
	phy->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
	if (IS_ERR(phy->gpiod_reset)) {
		nfc_err(dev, "Unable to get RESET GPIO\n");
		return -ENODEV;
	}

	phy->se_status.is_ese_present =
				device_property_read_bool(dev, "ese-present");
	phy->se_status.is_uicc_present =
				device_property_read_bool(dev, "uicc-present");

	r = ndlc_probe(phy, &i2c_phy_ops, &client->dev,
			ST_NCI_FRAME_HEADROOM, ST_NCI_FRAME_TAILROOM,
			&phy->ndlc, &phy->se_status);
	if (r < 0) {
		nfc_err(&client->dev, "Unable to register ndlc layer\n");
		return r;
	}

	phy->irq_active = true;
	r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
				st_nci_irq_thread_fn,
				IRQF_ONESHOT,
				ST_NCI_DRIVER_NAME, phy);
	if (r < 0)
		nfc_err(&client->dev, "Unable to register IRQ handler\n");

	return r;
}

static int st_nci_i2c_remove(struct i2c_client *client)
{
	struct st_nci_i2c_phy *phy = i2c_get_clientdata(client);

	ndlc_remove(phy->ndlc);

	return 0;
}

static const struct i2c_device_id st_nci_i2c_id_table[] = {
	{ST_NCI_DRIVER_NAME, 0},
	{}
};
MODULE_DEVICE_TABLE(i2c, st_nci_i2c_id_table);

static const struct acpi_device_id st_nci_i2c_acpi_match[] __maybe_unused = {
	{"SMO2101"},
	{"SMO2102"},
	{}
};
MODULE_DEVICE_TABLE(acpi, st_nci_i2c_acpi_match);

static const struct of_device_id of_st_nci_i2c_match[] __maybe_unused = {
	{ .compatible = "st,st21nfcb-i2c", },
	{ .compatible = "st,st21nfcb_i2c", },
	{ .compatible = "st,st21nfcc-i2c", },
	{}
};
MODULE_DEVICE_TABLE(of, of_st_nci_i2c_match);

static struct i2c_driver st_nci_i2c_driver = {
	.driver = {
		.name = ST_NCI_I2C_DRIVER_NAME,
		.of_match_table = of_match_ptr(of_st_nci_i2c_match),
		.acpi_match_table = ACPI_PTR(st_nci_i2c_acpi_match),
	},
	.probe = st_nci_i2c_probe,
	.id_table = st_nci_i2c_id_table,
	.remove = st_nci_i2c_remove,
};
module_i2c_driver(st_nci_i2c_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);