// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2015 Infineon Technologies AG
 * Copyright (C) 2016 STMicroelectronics SAS
 *
 * Authors:
 * Peter Huewe <peter.huewe@infineon.com>
 * Christophe Ricard <christophe-h.ricard@st.com>
 *
 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
 *
 * Device driver for TCG/TCPA TPM (trusted platform module).
 * Specifications at www.trustedcomputinggroup.org
 *
 * This device driver implements the TPM interface as defined in
 * the TCG TPM Interface Spec version 1.3, revision 27 via _raw/native
 * SPI access_.
 *
 * It is based on the original tpm_tis device driver from Leendert van
 * Dorn and Kyleen Hall and Jarko Sakkinnen.
 */

#include <linux/acpi.h>
#include <linux/completion.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>

#include <linux/of.h>
#include <linux/spi/spi.h>
#include <linux/tpm.h>

#include "tpm.h"
#include "tpm_tis_core.h"
#include "tpm_tis_spi.h"

#define MAX_SPI_FRAMESIZE 64
#define SPI_HDRSIZE 4

/*
 * TCG SPI flow control is documented in section 6.4 of the spec[1]. In short,
 * keep trying to read from the device until MISO goes high indicating the
 * wait state has ended.
 *
 * [1] https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
 */
static int tpm_tis_spi_flow_control(struct tpm_tis_spi_phy *phy,
                                    struct spi_transfer *spi_xfer)
{
        struct spi_message m;
        int ret, i;

        if ((phy->iobuf[3] & 0x01) == 0) {
                // handle SPI wait states
                for (i = 0; i < TPM_RETRY; i++) {
                        spi_xfer->len = 1;
                        spi_message_init(&m);
                        spi_message_add_tail(spi_xfer, &m);
                        ret = spi_sync_locked(phy->spi_device, &m);
                        if (ret < 0)
                                return ret;
                        if (phy->iobuf[0] & 0x01)
                                break;
                }

                if (i == TPM_RETRY)
                        return -ETIMEDOUT;
        }

        return 0;
}

/*
 * Half duplex controller with support for TPM wait state detection like
 * Tegra QSPI need CMD, ADDR & DATA sent in single message to manage HW flow
 * control. Each phase sent in different transfer for controller to idenity
 * phase.
 */
static int tpm_tis_spi_transfer_half(struct tpm_tis_data *data, u32 addr,
                                     u16 len, u8 *in, const u8 *out)
{
        struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
        struct spi_transfer spi_xfer[3];
        struct spi_message m;
        u8 transfer_len;
        int ret;

        while (len) {
                transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);

                spi_message_init(&m);
                phy->iobuf[0] = (in ? 0x80 : 0) | (transfer_len - 1);
                phy->iobuf[1] = 0xd4;
                phy->iobuf[2] = addr >> 8;
                phy->iobuf[3] = addr;

                memset(&spi_xfer, 0, sizeof(spi_xfer));

                spi_xfer[0].tx_buf = phy->iobuf;
                spi_xfer[0].len = 1;
                spi_message_add_tail(&spi_xfer[0], &m);

                spi_xfer[1].tx_buf = phy->iobuf + 1;
                spi_xfer[1].len = 3;
                spi_message_add_tail(&spi_xfer[1], &m);

                if (out) {
                        spi_xfer[2].tx_buf = &phy->iobuf[4];
                        spi_xfer[2].rx_buf = NULL;
                        memcpy(&phy->iobuf[4], out, transfer_len);
                        out += transfer_len;
                }

                if (in) {
                        spi_xfer[2].tx_buf = NULL;
                        spi_xfer[2].rx_buf = &phy->iobuf[4];
                }

                spi_xfer[2].len = transfer_len;
                spi_message_add_tail(&spi_xfer[2], &m);

                reinit_completion(&phy->ready);

                ret = spi_sync(phy->spi_device, &m);
                if (ret < 0)
                        return ret;

                if (in) {
                        memcpy(in, &phy->iobuf[4], transfer_len);
                        in += transfer_len;
                }

                len -= transfer_len;
        }

        return ret;
}

static int tpm_tis_spi_transfer_full(struct tpm_tis_data *data, u32 addr,
                                     u16 len, u8 *in, const u8 *out)
{
        struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
        int ret = 0;
        struct spi_message m;
        struct spi_transfer spi_xfer;
        u8 transfer_len;

        spi_bus_lock(phy->spi_device->controller);

        while (len) {
                transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);

                phy->iobuf[0] = (in ? 0x80 : 0) | (transfer_len - 1);
                phy->iobuf[1] = 0xd4;
                phy->iobuf[2] = addr >> 8;
                phy->iobuf[3] = addr;

                memset(&spi_xfer, 0, sizeof(spi_xfer));
                spi_xfer.tx_buf = phy->iobuf;
                spi_xfer.rx_buf = phy->iobuf;
                spi_xfer.len = 4;
                spi_xfer.cs_change = 1;

                spi_message_init(&m);
                spi_message_add_tail(&spi_xfer, &m);
                ret = spi_sync_locked(phy->spi_device, &m);
                if (ret < 0)
                        goto exit;

                /* Flow control transfers are receive only */
                spi_xfer.tx_buf = NULL;
                ret = phy->flow_control(phy, &spi_xfer);
                if (ret < 0)
                        goto exit;

                spi_xfer.cs_change = 0;
                spi_xfer.len = transfer_len;
                spi_xfer.delay.value = 5;
                spi_xfer.delay.unit = SPI_DELAY_UNIT_USECS;

                if (out) {
                        spi_xfer.tx_buf = phy->iobuf;
                        spi_xfer.rx_buf = NULL;
                        memcpy(phy->iobuf, out, transfer_len);
                        out += transfer_len;
                }

                spi_message_init(&m);
                spi_message_add_tail(&spi_xfer, &m);
                reinit_completion(&phy->ready);
                ret = spi_sync_locked(phy->spi_device, &m);
                if (ret < 0)
                        goto exit;

                if (in) {
                        memcpy(in, phy->iobuf, transfer_len);
                        in += transfer_len;
                }

                len -= transfer_len;
        }

exit:
        if (ret < 0) {
                /* Deactivate chip select */
                memset(&spi_xfer, 0, sizeof(spi_xfer));
                spi_message_init(&m);
                spi_message_add_tail(&spi_xfer, &m);
                spi_sync_locked(phy->spi_device, &m);
        }

        spi_bus_unlock(phy->spi_device->controller);
        return ret;
}

int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
                         u8 *in, const u8 *out)
{
        struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
        struct spi_controller *ctlr = phy->spi_device->controller;

        /*
         * TPM flow control over SPI requires full duplex support.
         * Send entire message to a half duplex controller to handle
         * wait polling in controller.
         * Set TPM HW flow control flag..
         */
        if (ctlr->flags & SPI_CONTROLLER_HALF_DUPLEX)
                return tpm_tis_spi_transfer_half(data, addr, len, in, out);
        else
                return tpm_tis_spi_transfer_full(data, addr, len, in, out);
}

static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
                                  u16 len, u8 *result, enum tpm_tis_io_mode io_mode)
{
        return tpm_tis_spi_transfer(data, addr, len, result, NULL);
}

static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
                                   u16 len, const u8 *value, enum tpm_tis_io_mode io_mode)
{
        return tpm_tis_spi_transfer(data, addr, len, NULL, value);
}

int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
                     int irq, const struct tpm_tis_phy_ops *phy_ops)
{
        phy->iobuf = devm_kmalloc(&spi->dev, SPI_HDRSIZE + MAX_SPI_FRAMESIZE, GFP_KERNEL);
        if (!phy->iobuf)
                return -ENOMEM;

        phy->spi_device = spi;

        return tpm_tis_core_init(&spi->dev, &phy->priv, irq, phy_ops, NULL);
}

static const struct tpm_tis_phy_ops tpm_spi_phy_ops = {
        .read_bytes = tpm_tis_spi_read_bytes,
        .write_bytes = tpm_tis_spi_write_bytes,
};

static int tpm_tis_spi_probe(struct spi_device *dev)
{
        struct tpm_tis_spi_phy *phy;
        int irq;

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

        phy->flow_control = tpm_tis_spi_flow_control;

        if (dev->controller->flags & SPI_CONTROLLER_HALF_DUPLEX)
                dev->mode |= SPI_TPM_HW_FLOW;

        /* If the SPI device has an IRQ then use that */
        if (dev->irq > 0)
                irq = dev->irq;
        else
                irq = -1;

        init_completion(&phy->ready);
        return tpm_tis_spi_init(dev, phy, irq, &tpm_spi_phy_ops);
}

typedef int (*tpm_tis_spi_probe_func)(struct spi_device *);

static int tpm_tis_spi_driver_probe(struct spi_device *spi)
{
        const struct spi_device_id *spi_dev_id = spi_get_device_id(spi);
        tpm_tis_spi_probe_func probe_func;

        probe_func = of_device_get_match_data(&spi->dev);
        if (!probe_func) {
                if (spi_dev_id) {
                        probe_func = (tpm_tis_spi_probe_func)spi_dev_id->driver_data;
                        if (!probe_func)
                                return -ENODEV;
                } else
                        probe_func = tpm_tis_spi_probe;
        }

        return probe_func(spi);
}

static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_spi_resume);

static void tpm_tis_spi_remove(struct spi_device *dev)
{
        struct tpm_chip *chip = spi_get_drvdata(dev);

        tpm_chip_unregister(chip);
        tpm_tis_remove(chip);
}

static const struct spi_device_id tpm_tis_spi_id[] = {
        { "attpm20p", (unsigned long)tpm_tis_spi_probe },
        { "st33htpm-spi", (unsigned long)tpm_tis_spi_probe },
        { "slb9670", (unsigned long)tpm_tis_spi_probe },
        { "tpm_tis_spi", (unsigned long)tpm_tis_spi_probe },
        { "tpm_tis-spi", (unsigned long)tpm_tis_spi_probe },
        { "cr50", (unsigned long)cr50_spi_probe },
        {}
};
MODULE_DEVICE_TABLE(spi, tpm_tis_spi_id);

static const struct of_device_id of_tis_spi_match[] __maybe_unused = {
        { .compatible = "atmel,attpm20p", .data = tpm_tis_spi_probe },
        { .compatible = "st,st33htpm-spi", .data = tpm_tis_spi_probe },
        { .compatible = "infineon,slb9670", .data = tpm_tis_spi_probe },
        { .compatible = "tcg,tpm_tis-spi", .data = tpm_tis_spi_probe },
        { .compatible = "google,cr50", .data = cr50_spi_probe },
        {}
};
MODULE_DEVICE_TABLE(of, of_tis_spi_match);

static const struct acpi_device_id acpi_tis_spi_match[] __maybe_unused = {
        {"SMO0768", 0},
        {}
};
MODULE_DEVICE_TABLE(acpi, acpi_tis_spi_match);

static struct spi_driver tpm_tis_spi_driver = {
        .driver = {
                .name = "tpm_tis_spi",
                .pm = &tpm_tis_pm,
                .of_match_table = of_match_ptr(of_tis_spi_match),
                .acpi_match_table = ACPI_PTR(acpi_tis_spi_match),
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
        .probe = tpm_tis_spi_driver_probe,
        .remove = tpm_tis_spi_remove,
        .id_table = tpm_tis_spi_id,
};
module_spi_driver(tpm_tis_spi_driver);

MODULE_DESCRIPTION("TPM Driver for native SPI access");
MODULE_LICENSE("GPL");