// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * STMicroelectronics TPM SPI Linux driver for TPM ST33ZP24
 * Copyright (C) 2009 - 2016 STMicroelectronics
 */

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

#include "../tpm.h"
#include "st33zp24.h"

#define TPM_DATA_FIFO           0x24
#define TPM_INTF_CAPABILITY     0x14

#define TPM_DUMMY_BYTE          0x00

#define MAX_SPI_LATENCY         15
#define LOCALITY0               0

#define ST33ZP24_OK                                     0x5A
#define ST33ZP24_UNDEFINED_ERR                          0x80
#define ST33ZP24_BADLOCALITY                            0x81
#define ST33ZP24_TISREGISTER_UNKNOWN                    0x82
#define ST33ZP24_LOCALITY_NOT_ACTIVATED                 0x83
#define ST33ZP24_HASH_END_BEFORE_HASH_START             0x84
#define ST33ZP24_BAD_COMMAND_ORDER                      0x85
#define ST33ZP24_INCORECT_RECEIVED_LENGTH               0x86
#define ST33ZP24_TPM_FIFO_OVERFLOW                      0x89
#define ST33ZP24_UNEXPECTED_READ_FIFO                   0x8A
#define ST33ZP24_UNEXPECTED_WRITE_FIFO                  0x8B
#define ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END    0x90
#define ST33ZP24_DUMMY_BYTES                            0x00

/*
 * TPM command can be up to 2048 byte, A TPM response can be up to
 * 1024 byte.
 * Between command and response, there are latency byte (up to 15
 * usually on st33zp24 2 are enough).
 *
 * Overall when sending a command and expecting an answer we need if
 * worst case:
 * 2048 (for the TPM command) + 1024 (for the TPM answer).  We need
 * some latency byte before the answer is available (max 15).
 * We have 2048 + 1024 + 15.
 */
#define ST33ZP24_SPI_BUFFER_SIZE (ST33ZP24_BUFSIZE + (ST33ZP24_BUFSIZE / 2) +\
                                  MAX_SPI_LATENCY)


struct st33zp24_spi_phy {
        struct spi_device *spi_device;

        u8 tx_buf[ST33ZP24_SPI_BUFFER_SIZE];
        u8 rx_buf[ST33ZP24_SPI_BUFFER_SIZE];

        int latency;
};

static int st33zp24_status_to_errno(u8 code)
{
        switch (code) {
        case ST33ZP24_OK:
                return 0;
        case ST33ZP24_UNDEFINED_ERR:
        case ST33ZP24_BADLOCALITY:
        case ST33ZP24_TISREGISTER_UNKNOWN:
        case ST33ZP24_LOCALITY_NOT_ACTIVATED:
        case ST33ZP24_HASH_END_BEFORE_HASH_START:
        case ST33ZP24_BAD_COMMAND_ORDER:
        case ST33ZP24_UNEXPECTED_READ_FIFO:
        case ST33ZP24_UNEXPECTED_WRITE_FIFO:
        case ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END:
                return -EPROTO;
        case ST33ZP24_INCORECT_RECEIVED_LENGTH:
        case ST33ZP24_TPM_FIFO_OVERFLOW:
                return -EMSGSIZE;
        case ST33ZP24_DUMMY_BYTES:
                return -ENOSYS;
        }
        return code;
}

/*
 * st33zp24_spi_send
 * Send byte to the TIS register according to the ST33ZP24 SPI protocol.
 * @param: phy_id, the phy description
 * @param: tpm_register, the tpm tis register where the data should be written
 * @param: tpm_data, the tpm_data to write inside the tpm_register
 * @param: tpm_size, The length of the data
 * @return: should be zero if success else a negative error code.
 */
static int st33zp24_spi_send(void *phy_id, u8 tpm_register, u8 *tpm_data,
                             int tpm_size)
{
        int total_length = 0, ret = 0;
        struct st33zp24_spi_phy *phy = phy_id;
        struct spi_device *dev = phy->spi_device;
        struct spi_transfer spi_xfer = {
                .tx_buf = phy->tx_buf,
                .rx_buf = phy->rx_buf,
        };

        /* Pre-Header */
        phy->tx_buf[total_length++] = TPM_WRITE_DIRECTION | LOCALITY0;
        phy->tx_buf[total_length++] = tpm_register;

        if (tpm_size > 0 && tpm_register == TPM_DATA_FIFO) {
                phy->tx_buf[total_length++] = tpm_size >> 8;
                phy->tx_buf[total_length++] = tpm_size;
        }

        memcpy(&phy->tx_buf[total_length], tpm_data, tpm_size);
        total_length += tpm_size;

        memset(&phy->tx_buf[total_length], TPM_DUMMY_BYTE, phy->latency);

        spi_xfer.len = total_length + phy->latency;

        ret = spi_sync_transfer(dev, &spi_xfer, 1);
        if (ret == 0)
                ret = phy->rx_buf[total_length + phy->latency - 1];

        return st33zp24_status_to_errno(ret);
} /* st33zp24_spi_send() */

/*
 * st33zp24_spi_read8_recv
 * Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
 * @param: phy_id, the phy description
 * @param: tpm_register, the tpm tis register where the data should be read
 * @param: tpm_data, the TPM response
 * @param: tpm_size, tpm TPM response size to read.
 * @return: should be zero if success else a negative error code.
 */
static int st33zp24_spi_read8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data,
                                  int tpm_size)
{
        int total_length = 0, ret;
        struct st33zp24_spi_phy *phy = phy_id;
        struct spi_device *dev = phy->spi_device;
        struct spi_transfer spi_xfer = {
                .tx_buf = phy->tx_buf,
                .rx_buf = phy->rx_buf,
        };

        /* Pre-Header */
        phy->tx_buf[total_length++] = LOCALITY0;
        phy->tx_buf[total_length++] = tpm_register;

        memset(&phy->tx_buf[total_length], TPM_DUMMY_BYTE,
               phy->latency + tpm_size);

        spi_xfer.len = total_length + phy->latency + tpm_size;

        /* header + status byte + size of the data + status byte */
        ret = spi_sync_transfer(dev, &spi_xfer, 1);
        if (tpm_size > 0 && ret == 0) {
                ret = phy->rx_buf[total_length + phy->latency - 1];

                memcpy(tpm_data, phy->rx_buf + total_length + phy->latency,
                       tpm_size);
        }

        return ret;
} /* st33zp24_spi_read8_reg() */

/*
 * st33zp24_spi_recv
 * Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
 * @param: phy_id, the phy description
 * @param: tpm_register, the tpm tis register where the data should be read
 * @param: tpm_data, the TPM response
 * @param: tpm_size, tpm TPM response size to read.
 * @return: number of byte read successfully: should be one if success.
 */
static int st33zp24_spi_recv(void *phy_id, u8 tpm_register, u8 *tpm_data,
                             int tpm_size)
{
        int ret;

        ret = st33zp24_spi_read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
        if (!st33zp24_status_to_errno(ret))
                return tpm_size;
        return ret;
} /* st33zp24_spi_recv() */

static int st33zp24_spi_evaluate_latency(void *phy_id)
{
        struct st33zp24_spi_phy *phy = phy_id;
        int latency = 1, status = 0;
        u8 data = 0;

        while (!status && latency < MAX_SPI_LATENCY) {
                phy->latency = latency;
                status = st33zp24_spi_read8_reg(phy_id, TPM_INTF_CAPABILITY,
                                                &data, 1);
                latency++;
        }
        if (status < 0)
                return status;
        if (latency == MAX_SPI_LATENCY)
                return -ENODEV;

        return latency - 1;
} /* evaluate_latency() */

static const struct st33zp24_phy_ops spi_phy_ops = {
        .send = st33zp24_spi_send,
        .recv = st33zp24_spi_recv,
};

/*
 * st33zp24_spi_probe initialize the TPM device
 * @param: dev, the spi_device description (TPM SPI description).
 * @return: 0 in case of success.
 *       or a negative value describing the error.
 */
static int st33zp24_spi_probe(struct spi_device *dev)
{
        struct st33zp24_spi_phy *phy;

        phy = devm_kzalloc(&dev->dev, sizeof(struct st33zp24_spi_phy),
                           GFP_KERNEL);
        if (!phy)
                return -ENOMEM;

        phy->spi_device = dev;

        phy->latency = st33zp24_spi_evaluate_latency(phy);
        if (phy->latency <= 0)
                return -ENODEV;

        return st33zp24_probe(phy, &spi_phy_ops, &dev->dev, dev->irq);
}

/*
 * st33zp24_spi_remove remove the TPM device
 * @param: client, the spi_device description (TPM SPI description).
 * @return: 0 in case of success.
 */
static void st33zp24_spi_remove(struct spi_device *dev)
{
        struct tpm_chip *chip = spi_get_drvdata(dev);

        st33zp24_remove(chip);
}

static const struct spi_device_id st33zp24_spi_id[] = {
        {TPM_ST33_SPI, 0},
        {}
};
MODULE_DEVICE_TABLE(spi, st33zp24_spi_id);

static const struct of_device_id of_st33zp24_spi_match[] __maybe_unused = {
        { .compatible = "st,st33zp24-spi", },
        {}
};
MODULE_DEVICE_TABLE(of, of_st33zp24_spi_match);

static const struct acpi_device_id st33zp24_spi_acpi_match[] __maybe_unused = {
        {"SMO3324"},
        {}
};
MODULE_DEVICE_TABLE(acpi, st33zp24_spi_acpi_match);

static SIMPLE_DEV_PM_OPS(st33zp24_spi_ops, st33zp24_pm_suspend,
                         st33zp24_pm_resume);

static struct spi_driver st33zp24_spi_driver = {
        .driver = {
                .name = "st33zp24-spi",
                .pm = &st33zp24_spi_ops,
                .of_match_table = of_match_ptr(of_st33zp24_spi_match),
                .acpi_match_table = ACPI_PTR(st33zp24_spi_acpi_match),
        },
        .probe = st33zp24_spi_probe,
        .remove = st33zp24_spi_remove,
        .id_table = st33zp24_spi_id,
};

module_spi_driver(st33zp24_spi_driver);

MODULE_AUTHOR("TPM support <TPMsupport@list.st.com>");
MODULE_DESCRIPTION("STM TPM 1.2 SPI ST33 Driver");
MODULE_VERSION("1.3.0");
MODULE_LICENSE("GPL");