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

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/spi/spi.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 <net/nfc/nci.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_SPI_MIN_SIZE 4   /* PCB(1) + NCI Packet header(3) */
#define ST_NCI_SPI_MAX_SIZE 250 /* req 4.2.1 */

#define ST_NCI_DRIVER_NAME "st_nci"
#define ST_NCI_SPI_DRIVER_NAME "st_nci_spi"

struct st_nci_spi_phy {
        struct spi_device *spi_dev;
        struct llt_ndlc *ndlc;

        bool irq_active;

        struct gpio_desc *gpiod_reset;

        struct st_nci_se_status se_status;
};

static int st_nci_spi_enable(void *phy_id)
{
        struct st_nci_spi_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->spi_dev->irq);
                phy->irq_active = true;
        }

        return 0;
}

static void st_nci_spi_disable(void *phy_id)
{
        struct st_nci_spi_phy *phy = phy_id;

        disable_irq_nosync(phy->spi_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_spi_write(void *phy_id, struct sk_buff *skb)
{
        int r;
        struct st_nci_spi_phy *phy = phy_id;
        struct spi_device *dev = phy->spi_dev;
        struct sk_buff *skb_rx;
        u8 buf[ST_NCI_SPI_MAX_SIZE + NCI_DATA_HDR_SIZE +
               ST_NCI_FRAME_HEADROOM + ST_NCI_FRAME_TAILROOM];
        struct spi_transfer spi_xfer = {
                .tx_buf = skb->data,
                .rx_buf = buf,
                .len = skb->len,
        };

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

        r = spi_sync_transfer(dev, &spi_xfer, 1);
        /*
         * We may have received some valuable data on miso line.
         * Send them back in the ndlc state machine.
         */
        if (!r) {
                skb_rx = alloc_skb(skb->len, GFP_KERNEL);
                if (!skb_rx)
                        return -ENOMEM;

                skb_put(skb_rx, skb->len);
                memcpy(skb_rx->data, buf, skb->len);
                ndlc_recv(phy->ndlc, skb_rx);
        }

        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_spi_read(struct st_nci_spi_phy *phy,
                        struct sk_buff **skb)
{
        int r;
        u8 len;
        u8 buf[ST_NCI_SPI_MAX_SIZE];
        struct spi_device *dev = phy->spi_dev;
        struct spi_transfer spi_xfer = {
                .rx_buf = buf,
                .len = ST_NCI_SPI_MIN_SIZE,
        };

        r = spi_sync_transfer(dev, &spi_xfer, 1);
        if (r < 0)
                return -EREMOTEIO;

        len = be16_to_cpu(*(__be16 *) (buf + 2));
        if (len > ST_NCI_SPI_MAX_SIZE) {
                nfc_err(&dev->dev, "invalid frame len\n");
                phy->ndlc->hard_fault = 1;
                return -EBADMSG;
        }

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

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

        if (!len)
                return 0;

        spi_xfer.len = len;
        r = spi_sync_transfer(dev, &spi_xfer, 1);
        if (r < 0) {
                kfree_skb(*skb);
                return -EREMOTEIO;
        }

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

        return 0;
}

/*
 * Reads an ndlc frame from the chip.
 *
 * On ST21NFCB, IRQ goes in idle state when read starts.
 */
static irqreturn_t st_nci_irq_thread_fn(int irq, void *phy_id)
{
        struct st_nci_spi_phy *phy = phy_id;
        struct sk_buff *skb = NULL;
        int r;

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

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

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

        r = st_nci_spi_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 spi_phy_ops = {
        .write = st_nci_spi_write,
        .enable = st_nci_spi_enable,
        .disable = st_nci_spi_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_spi_probe(struct spi_device *dev)
{
        struct st_nci_spi_phy *phy;
        int r;

        /* Check SPI platform functionnalities */
        if (!dev) {
                pr_debug("%s: dev is NULL. Device is not accessible.\n",
                        __func__);
                return -ENODEV;
        }

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

        phy->spi_dev = dev;

        spi_set_drvdata(dev, phy);

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

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

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

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

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

        return r;
}

static void st_nci_spi_remove(struct spi_device *dev)
{
        struct st_nci_spi_phy *phy = spi_get_drvdata(dev);

        ndlc_remove(phy->ndlc);
}

static struct spi_device_id st_nci_spi_id_table[] = {
        {ST_NCI_SPI_DRIVER_NAME, 0},
        {"st21nfcb-spi", 0},
        {}
};
MODULE_DEVICE_TABLE(spi, st_nci_spi_id_table);

static const struct acpi_device_id st_nci_spi_acpi_match[] __maybe_unused = {
        {"SMO2101", 0},
        {}
};
MODULE_DEVICE_TABLE(acpi, st_nci_spi_acpi_match);

static const struct of_device_id of_st_nci_spi_match[] __maybe_unused = {
        { .compatible = "st,st21nfcb-spi", },
        {}
};
MODULE_DEVICE_TABLE(of, of_st_nci_spi_match);

static struct spi_driver st_nci_spi_driver = {
        .driver = {
                .name = ST_NCI_SPI_DRIVER_NAME,
                .of_match_table = of_match_ptr(of_st_nci_spi_match),
                .acpi_match_table = ACPI_PTR(st_nci_spi_acpi_match),
        },
        .probe = st_nci_spi_probe,
        .id_table = st_nci_spi_id_table,
        .remove = st_nci_spi_remove,
};
module_spi_driver(st_nci_spi_driver);

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