// 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 sk_buff *skb = NULL;
        int r;

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

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

        ndlc_remove(phy->ndlc);
}

static const struct i2c_device_id st_nci_i2c_id_table[] = {
        { ST_NCI_DRIVER_NAME },
        {}
};
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);