/*
 * 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.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
#include <linux/acpi.h>
#include <linux/freezer.h>

#include <linux/module.h>
#include <linux/spi/spi.h>
#include <linux/gpio.h>
#include <linux/of_irq.h>
#include <linux/of_gpio.h>
#include <linux/tpm.h>
#include "tpm.h"
#include "tpm_tis_core.h"

#define MAX_SPI_FRAMESIZE 64

struct tpm_tis_spi_phy {
        struct tpm_tis_data priv;
        struct spi_device *spi_device;

        u8 tx_buf[MAX_SPI_FRAMESIZE + 4];
        u8 rx_buf[MAX_SPI_FRAMESIZE + 4];
};

static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *data)
{
        return container_of(data, struct tpm_tis_spi_phy, priv);
}

static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
                                  u16 len, u8 *result)
{
        struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
        int ret, i;
        struct spi_message m;
        struct spi_transfer spi_xfer = {
                .tx_buf = phy->tx_buf,
                .rx_buf = phy->rx_buf,
                .len = 4,
        };

        if (len > MAX_SPI_FRAMESIZE)
                return -ENOMEM;

        phy->tx_buf[0] = 0x80 | (len - 1);
        phy->tx_buf[1] = 0xd4;
        phy->tx_buf[2] = (addr >> 8)  & 0xFF;
        phy->tx_buf[3] = addr         & 0xFF;

        spi_xfer.cs_change = 1;
        spi_message_init(&m);
        spi_message_add_tail(&spi_xfer, &m);

        spi_bus_lock(phy->spi_device->master);
        ret = spi_sync_locked(phy->spi_device, &m);
        if (ret < 0)
                goto exit;

        memset(phy->tx_buf, 0, len);

        /* According to TCG PTP specification, if there is no TPM present at
         * all, then the design has a weak pull-up on MISO. If a TPM is not
         * present, a pull-up on MISO means that the SB controller sees a 1,
         * and will latch in 0xFF on the read.
         */
        for (i = 0; (phy->rx_buf[0] & 0x01) == 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)
                        goto exit;
        }

        spi_xfer.cs_change = 0;
        spi_xfer.len = len;
        spi_xfer.rx_buf = result;

        spi_message_init(&m);
        spi_message_add_tail(&spi_xfer, &m);
        ret = spi_sync_locked(phy->spi_device, &m);

exit:
        spi_bus_unlock(phy->spi_device->master);
        return ret;
}

static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
                                   u16 len, u8 *value)
{
        struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
        int ret, i;
        struct spi_message m;
        struct spi_transfer spi_xfer = {
                .tx_buf = phy->tx_buf,
                .rx_buf = phy->rx_buf,
                .len = 4,
        };

        if (len > MAX_SPI_FRAMESIZE)
                return -ENOMEM;

        phy->tx_buf[0] = len - 1;
        phy->tx_buf[1] = 0xd4;
        phy->tx_buf[2] = (addr >> 8)  & 0xFF;
        phy->tx_buf[3] = addr         & 0xFF;

        spi_xfer.cs_change = 1;
        spi_message_init(&m);
        spi_message_add_tail(&spi_xfer, &m);

        spi_bus_lock(phy->spi_device->master);
        ret = spi_sync_locked(phy->spi_device, &m);
        if (ret < 0)
                goto exit;

        memset(phy->tx_buf, 0, len);

        /* According to TCG PTP specification, if there is no TPM present at
         * all, then the design has a weak pull-up on MISO. If a TPM is not
         * present, a pull-up on MISO means that the SB controller sees a 1,
         * and will latch in 0xFF on the read.
         */
        for (i = 0; (phy->rx_buf[0] & 0x01) == 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)
                        goto exit;
        }

        spi_xfer.len = len;
        spi_xfer.tx_buf = value;
        spi_xfer.cs_change = 0;
        spi_xfer.tx_buf = value;
        spi_message_init(&m);
        spi_message_add_tail(&spi_xfer, &m);
        ret = spi_sync_locked(phy->spi_device, &m);

exit:
        spi_bus_unlock(phy->spi_device->master);
        return ret;
}

static int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result)
{
        int rc;

        rc = data->phy_ops->read_bytes(data, addr, sizeof(u16), (u8 *)result);
        if (!rc)
                *result = le16_to_cpu(*result);
        return rc;
}

static int tpm_tis_spi_read32(struct tpm_tis_data *data, u32 addr, u32 *result)
{
        int rc;

        rc = data->phy_ops->read_bytes(data, addr, sizeof(u32), (u8 *)result);
        if (!rc)
                *result = le32_to_cpu(*result);
        return rc;
}

static int tpm_tis_spi_write32(struct tpm_tis_data *data, u32 addr, u32 value)
{
        value = cpu_to_le32(value);
        return data->phy_ops->write_bytes(data, addr, sizeof(u32),
                                           (u8 *)&value);
}

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,
        .read16 = tpm_tis_spi_read16,
        .read32 = tpm_tis_spi_read32,
        .write32 = tpm_tis_spi_write32,
};

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

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

        phy->spi_device = dev;

        return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_spi_phy_ops,
                                 NULL);
}

static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_resume);

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

        tpm_chip_unregister(chip);
        tpm_tis_remove(chip);
        return 0;
}

static const struct spi_device_id tpm_tis_spi_id[] = {
        {"tpm_tis_spi", 0},
        {}
};
MODULE_DEVICE_TABLE(spi, tpm_tis_spi_id);

static const struct of_device_id of_tis_spi_match[] = {
        { .compatible = "st,st33htpm-spi", },
        { .compatible = "infineon,slb9670", },
        { .compatible = "tcg,tpm_tis-spi", },
        {}
};
MODULE_DEVICE_TABLE(of, of_tis_spi_match);

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

static struct spi_driver tpm_tis_spi_driver = {
        .driver = {
                .owner = THIS_MODULE,
                .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 = tpm_tis_spi_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");