// SPDX-License-Identifier: GPL-2.0+
/*
 * STMicroelectronics TPM ST33ZP24 SPI UBOOT driver
 *
 * Copyright (C) 2016, STMicroelectronics - All Rights Reserved
 * Author(s): Christophe Ricard <christophe-h.ricard@st.com> for STMicroelectronics.
 *
 * Description: Device driver for ST33ZP24 SPI TPM TCG.
 *
 * This device driver implements the TPM interface as defined in
 * the TCG TPM Interface Spec version 1.21, revision 1.0 and the
 * STMicroelectronics Protocol Stack Specification version 1.2.0.
 */

#include <common.h>
#include <dm.h>
#include <fdtdec.h>
#include <log.h>
#include <spi.h>
#include <tpm-v1.h>
#include <errno.h>
#include <linux/delay.h>
#include <linux/types.h>
#include <asm/unaligned.h>
#include <linux/compat.h>

#include "tpm_tis.h"
#include "tpm_internal.h"

#define TPM_ACCESS                      0x0
#define TPM_STS                         0x18
#define TPM_DATA_FIFO                   0x24

#define LOCALITY0                       0

#define TPM_DATA_FIFO                           0x24
#define TPM_INTF_CAPABILITY                     0x14

#define TPM_DUMMY_BYTE                          0x00
#define TPM_WRITE_DIRECTION                     0x80

#define MAX_SPI_LATENCY                         15
#define LOCALITY0                               0

#define ST33ZP24_OK                                     0x5A
#define ST33ZP24_UNDEFINED_ERR                          0x80
#define ST33ZP24_BADLOCALITY                            0x81
#define ST33ZP24_TISREGISTER_UKNOWN                     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 (TPM_BUFSIZE + (TPM_BUFSIZE / 2) +\
                                  MAX_SPI_LATENCY)

struct st33zp24_spi_phy {
        int latency;

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

static int st33zp24_spi_status_to_errno(u8 code)
{
        switch (code) {
        case ST33ZP24_OK:
                return 0;
        case ST33ZP24_UNDEFINED_ERR:
        case ST33ZP24_BADLOCALITY:
        case ST33ZP24_TISREGISTER_UKNOWN:
        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 TPM register according to the ST33ZP24 SPI protocol.
 * @param: tpm, the chip 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_write(struct udevice *dev, u8 tpm_register,
                              const u8 *tpm_data, size_t tpm_size)
{
        int total_length = 0, ret;
        struct spi_slave *slave = dev_get_parent_priv(dev);
        struct st33zp24_spi_phy *phy = dev_get_plat(dev);

        u8 *tx_buf = (u8 *)phy->tx_buf;
        u8 *rx_buf = phy->rx_buf;

        tx_buf[total_length++] = TPM_WRITE_DIRECTION | LOCALITY0;
        tx_buf[total_length++] = tpm_register;

        if (tpm_size > 0 && tpm_register == TPM_DATA_FIFO) {
                tx_buf[total_length++] = tpm_size >> 8;
                tx_buf[total_length++] = tpm_size;
        }
        memcpy(tx_buf + total_length, tpm_data, tpm_size);
        total_length += tpm_size;

        memset(tx_buf + total_length, TPM_DUMMY_BYTE, phy->latency);

        total_length += phy->latency;

        ret = spi_claim_bus(slave);
        if (ret < 0)
                return ret;

        ret = spi_xfer(slave, total_length * 8, tx_buf, rx_buf,
                       SPI_XFER_BEGIN | SPI_XFER_END);
        if (ret < 0)
                return ret;

        spi_release_bus(slave);

        if (ret == 0)
                ret = rx_buf[total_length - 1];

        return st33zp24_spi_status_to_errno(ret);
}

/*
 * spi_st33zp24_spi_read8_reg
 * Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
 * @param: tpm, the chip description
 * @param: tpm_loc, the locality to read register from
 * @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 u8 st33zp24_spi_read8_reg(struct udevice *dev, u8 tpm_register,
                                 u8 *tpm_data, size_t tpm_size)
{
        int total_length = 0, ret;
        struct spi_slave *slave = dev_get_parent_priv(dev);
        struct st33zp24_spi_phy *phy = dev_get_plat(dev);

        u8 *tx_buf = (u8 *)phy->tx_buf;
        u8 *rx_buf = phy->rx_buf;

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

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

        ret = spi_claim_bus(slave);
        if (ret < 0)
                return 0;

        ret = spi_xfer(slave, total_length * 8, tx_buf, rx_buf,
                       SPI_XFER_BEGIN | SPI_XFER_END);
        if (ret < 0)
                return 0;

        spi_release_bus(slave);

        if (tpm_size > 0 && ret == 0) {
                ret = rx_buf[total_length - tpm_size - 1];
                memcpy(tpm_data, rx_buf + total_length - tpm_size, tpm_size);
        }
        return ret;
}

/*
 * 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_read(struct udevice *dev, u8 tpm_register,
                             u8 *tpm_data, size_t tpm_size)
{
        int ret;

        ret = st33zp24_spi_read8_reg(dev, tpm_register, tpm_data, tpm_size);
        if (!st33zp24_spi_status_to_errno(ret))
                return tpm_size;

        return ret;
}

static int st33zp24_spi_evaluate_latency(struct udevice *dev)
{
        int latency = 1, status = 0;
        u8 data = 0;
        struct st33zp24_spi_phy *phy = dev_get_plat(dev);

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

        return latency - 1;
}

/*
 * st33zp24_spi_release_locality release the active locality
 * @param: chip, the tpm chip description.
 */
static void st33zp24_spi_release_locality(struct udevice *dev)
{
        u8 data = TPM_ACCESS_ACTIVE_LOCALITY;

        st33zp24_spi_write(dev, TPM_ACCESS, &data, 1);
}

/*
 * st33zp24_spi_check_locality if the locality is active
 * @param: chip, the tpm chip description
 * @return: the active locality or -EACCES.
 */
static int st33zp24_spi_check_locality(struct udevice *dev)
{
        u8 data;
        u8 status;
        struct tpm_chip *chip = dev_get_priv(dev);

        status = st33zp24_spi_read(dev, TPM_ACCESS, &data, 1);
        if (status && (data &
                (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) ==
                (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID))
                return chip->locality;

        return -EACCES;
}

/*
 * st33zp24_spi_request_locality request the TPM locality
 * @param: chip, the chip description
 * @return: the active locality or negative value.
 */
static int st33zp24_spi_request_locality(struct udevice *dev)
{
        unsigned long start, stop;
        long ret;
        u8 data;
        struct tpm_chip *chip = dev_get_priv(dev);

        if (st33zp24_spi_check_locality(dev) == chip->locality)
                return chip->locality;

        data = TPM_ACCESS_REQUEST_USE;
        ret = st33zp24_spi_write(dev, TPM_ACCESS, &data, 1);
        if (ret < 0)
                return ret;

        /* wait for locality activated */
        start = get_timer(0);
        stop = chip->timeout_a;
        do {
                if (st33zp24_spi_check_locality(dev) >= 0)
                        return chip->locality;
                udelay(TPM_TIMEOUT_MS * 1000);
        } while  (get_timer(start) < stop);

        return -EACCES;
}

/*
 * st33zp24_spi_status return the TPM_STS register
 * @param: chip, the tpm chip description
 * @return: the TPM_STS register value.
 */
static u8 st33zp24_spi_status(struct udevice *dev)
{
        u8 data;

        st33zp24_spi_read(dev, TPM_STS, &data, 1);
        return data;
}

/*
 * st33zp24_spi_get_burstcount return the burstcount address 0x19 0x1A
 * @param: chip, the chip description
 * return: the burstcount or -TPM_DRIVER_ERR in case of error.
 */
static int st33zp24_spi_get_burstcount(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        unsigned long start, stop;
        int burstcnt, status;
        u8 tpm_reg, temp;

        /* wait for burstcount */
        start = get_timer(0);
        stop = chip->timeout_d;
        do {
                tpm_reg = TPM_STS + 1;
                status = st33zp24_spi_read(dev, tpm_reg, &temp, 1);
                if (status < 0)
                        return -EBUSY;

                tpm_reg = TPM_STS + 2;
                burstcnt = temp;
                status = st33zp24_spi_read(dev, tpm_reg, &temp, 1);
                if (status < 0)
                        return -EBUSY;

                burstcnt |= temp << 8;
                if (burstcnt)
                        return burstcnt;
                udelay(TIS_SHORT_TIMEOUT_MS * 1000);
        } while (get_timer(start) < stop);

        return -EBUSY;
}

/*
 * st33zp24_spi_cancel, cancel the current command execution or
 * set STS to COMMAND READY.
 * @param: chip, tpm_chip description.
 */
static void st33zp24_spi_cancel(struct udevice *dev)
{
        u8 data;

        data = TPM_STS_COMMAND_READY;
        st33zp24_spi_write(dev, TPM_STS, &data, 1);
}

/*
 * st33zp24_spi_wait_for_stat wait for a TPM_STS value
 * @param: chip, the tpm chip description
 * @param: mask, the value mask to wait
 * @param: timeout, the timeout
 * @param: status,
 * @return: the tpm status, 0 if success, -ETIME if timeout is reached.
 */
static int st33zp24_spi_wait_for_stat(struct udevice *dev, u8 mask,
                                  unsigned long timeout, int *status)
{
        unsigned long start, stop;

        /* Check current status */
        *status = st33zp24_spi_status(dev);
        if ((*status & mask) == mask)
                return 0;

        start = get_timer(0);
        stop = timeout;
        do {
                udelay(TPM_TIMEOUT_MS * 1000);
                *status = st33zp24_spi_status(dev);
                if ((*status & mask) == mask)
                        return 0;
        } while (get_timer(start) < stop);

        return -ETIME;
}

/*
 * st33zp24_spi_recv_data receive data
 * @param: chip, the tpm chip description
 * @param: buf, the buffer where the data are received
 * @param: count, the number of data to receive
 * @return: the number of bytes read from TPM FIFO.
 */
static int st33zp24_spi_recv_data(struct udevice *dev, u8 *buf, size_t count)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        int size = 0, burstcnt, len, ret, status;

        while (size < count &&
               st33zp24_spi_wait_for_stat(dev, TPM_STS_DATA_AVAIL | TPM_STS_VALID,
                                chip->timeout_c, &status) == 0) {
                burstcnt = st33zp24_spi_get_burstcount(dev);
                if (burstcnt < 0)
                        return burstcnt;
                len = min_t(int, burstcnt, count - size);
                ret = st33zp24_spi_read(dev, TPM_DATA_FIFO, buf + size, len);
                if (ret < 0)
                        return ret;

                size += len;
        }
        return size;
}

/*
 * st33zp24_spi_recv received TPM response through TPM phy.
 * @param: chip, tpm_chip description.
 * @param: buf, the buffer to store data.
 * @param: count, the number of bytes that can received (sizeof buf).
 * @return: Returns zero in case of success else -EIO.
 */
static int st33zp24_spi_recv(struct udevice *dev, u8 *buf, size_t count)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        int size;
        unsigned int expected;

        if (!chip)
                return -ENODEV;

        if (count < TPM_HEADER_SIZE) {
                size = -EIO;
                goto out;
        }

        size = st33zp24_spi_recv_data(dev, buf, TPM_HEADER_SIZE);
        if (size < TPM_HEADER_SIZE) {
                debug("TPM error, unable to read header\n");
                goto out;
        }

        expected = get_unaligned_be32(buf + 2);
        if (expected > count || expected < TPM_HEADER_SIZE) {
                size = -EIO;
                goto out;
        }

        size += st33zp24_spi_recv_data(dev, &buf[TPM_HEADER_SIZE],
                                   expected - TPM_HEADER_SIZE);
        if (size < expected) {
                debug("TPM error, unable to read remaining bytes of result\n");
                size = -EIO;
                goto out;
        }

out:
        st33zp24_spi_cancel(dev);
        st33zp24_spi_release_locality(dev);

        return size;
}

/*
 * st33zp24_spi_send send TPM commands through TPM phy.
 * @param: chip, tpm_chip description.
 * @param: buf, the buffer to send.
 * @param: len, the number of bytes to send.
 * @return: Returns zero in case of success else the negative error code.
 */
static int st33zp24_spi_send(struct udevice *dev, const u8 *buf, size_t len)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        u32 i, size;
        int burstcnt, ret, status;
        u8 data, tpm_stat;

        if (!chip)
                return -ENODEV;
        if (len < TPM_HEADER_SIZE)
                return -EIO;

        ret = st33zp24_spi_request_locality(dev);
        if (ret < 0)
                return ret;

        tpm_stat = st33zp24_spi_status(dev);
        if ((tpm_stat & TPM_STS_COMMAND_READY) == 0) {
                st33zp24_spi_cancel(dev);
                if (st33zp24_spi_wait_for_stat(dev, TPM_STS_COMMAND_READY,
                                               chip->timeout_b, &status) < 0) {
                        ret = -ETIME;
                        goto out_err;
                }
        }

        for (i = 0; i < len - 1;) {
                burstcnt = st33zp24_spi_get_burstcount(dev);
                if (burstcnt < 0)
                        return burstcnt;

                size = min_t(int, len - i - 1, burstcnt);
                ret = st33zp24_spi_write(dev, TPM_DATA_FIFO, buf + i, size);
                if (ret < 0)
                        goto out_err;

                i += size;
        }

        tpm_stat = st33zp24_spi_status(dev);
        if ((tpm_stat & TPM_STS_DATA_EXPECT) == 0) {
                ret = -EIO;
                goto out_err;
        }

        ret = st33zp24_spi_write(dev, TPM_DATA_FIFO, buf + len - 1, 1);
        if (ret < 0)
                goto out_err;

        tpm_stat = st33zp24_spi_status(dev);
        if ((tpm_stat & TPM_STS_DATA_EXPECT) != 0) {
                ret = -EIO;
                goto out_err;
        }

        data = TPM_STS_GO;
        ret = st33zp24_spi_write(dev, TPM_STS, &data, 1);
        if (ret < 0)
                goto out_err;

        return len;

out_err:
        st33zp24_spi_cancel(dev);
        st33zp24_spi_release_locality(dev);

        return ret;
}

static int st33zp24_spi_cleanup(struct udevice *dev)
{
        st33zp24_spi_cancel(dev);
        /*
         * The TPM needs some time to clean up here,
         * so we sleep rather than keeping the bus busy
         */
        mdelay(2);
        st33zp24_spi_release_locality(dev);

        return 0;
}

static int st33zp24_spi_init(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        struct st33zp24_spi_phy *phy = dev_get_plat(dev);

        chip->is_open = 1;

        /* Default timeouts - these could move to the device tree */
        chip->timeout_a = TIS_SHORT_TIMEOUT_MS;
        chip->timeout_b = TIS_LONG_TIMEOUT_MS;
        chip->timeout_c = TIS_SHORT_TIMEOUT_MS;
        chip->timeout_d = TIS_SHORT_TIMEOUT_MS;

        chip->locality = LOCALITY0;

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

        /*
         * A timeout query to TPM can be placed here.
         * Standard timeout values are used so far
         */

        return 0;
}

static int st33zp24_spi_open(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        int rc;

        debug("%s: start\n", __func__);
        if (chip->is_open)
                return -EBUSY;

        rc = st33zp24_spi_init(dev);
        if (rc < 0)
                chip->is_open = 0;

        return rc;
}

static int st33zp24_spi_close(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);

        if (chip->is_open) {
                st33zp24_spi_release_locality(dev);
                chip->is_open = 0;
                chip->vend_dev = 0;
        }

        return 0;
}

static int st33zp24_spi_get_desc(struct udevice *dev, char *buf, int size)
{
        struct tpm_chip *chip = dev_get_priv(dev);

        if (size < 50)
                return -ENOSPC;

        return snprintf(buf, size, "1.2 TPM (%s, chip type %s device-id 0x%x)",
                        chip->is_open ? "open" : "closed",
                        dev->name,
                        chip->vend_dev >> 16);
}

const struct tpm_ops st33zp24_spi_tpm_ops = {
        .open = st33zp24_spi_open,
        .close = st33zp24_spi_close,
        .recv = st33zp24_spi_recv,
        .send = st33zp24_spi_send,
        .cleanup = st33zp24_spi_cleanup,
        .get_desc = st33zp24_spi_get_desc,
};

static int st33zp24_spi_probe(struct udevice *dev)
{
        struct tpm_chip_priv *uc_priv = dev_get_uclass_priv(dev);

        uc_priv->duration_ms[TPM_SHORT] = TIS_SHORT_TIMEOUT_MS;
        uc_priv->duration_ms[TPM_MEDIUM] = TIS_LONG_TIMEOUT_MS;
        uc_priv->duration_ms[TPM_LONG] = TIS_LONG_TIMEOUT_MS;
        uc_priv->retry_time_ms = TPM_TIMEOUT_MS;

        debug("ST33ZP24 SPI TPM from STMicroelectronics found\n");

        return 0;
}

static int st33zp24_spi_remove(struct udevice *dev)
{
        st33zp24_spi_release_locality(dev);

        return 0;
}

static const struct udevice_id st33zp24_spi_ids[] = {
        { .compatible = "st,st33zp24-spi" },
        { }
};

U_BOOT_DRIVER(st33zp24_spi_spi) = {
        .name   = "st33zp24-spi",
        .id     = UCLASS_TPM,
        .of_match = of_match_ptr(st33zp24_spi_ids),
        .probe  = st33zp24_spi_probe,
        .remove = st33zp24_spi_remove,
        .ops = &st33zp24_spi_tpm_ops,
        .priv_auto      = sizeof(struct tpm_chip),
        .plat_auto      = sizeof(struct st33zp24_spi_phy),
};