/*
 * STMicroelectronics TPM ST33ZP24 I2C UBOOT driver
 *
 * Copyright (C) 2016 STMicroelectronics
 *
 * Description: Device driver for ST33ZP24 I2C 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.
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <dm.h>
#include <fdtdec.h>
#include <i2c.h>
#include <tpm.h>
#include <errno.h>
#include <linux/types.h>
#include <asm/unaligned.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_DUMMY_BYTE                  0xAA
#define TPM_ST33ZP24_I2C_SLAVE_ADDR     0x13

#define TPM_WRITE_DIRECTION             0x80

/*
 * st33zp24_i2c_write8_reg
 * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
 * @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: Number of byte written successfully else an error code.
 */
static int st33zp24_i2c_write8_reg(struct udevice *dev, u8 tpm_register,
                                   const u8 *tpm_data, size_t tpm_size)
{
        struct tpm_chip_priv *chip_priv = dev_get_uclass_priv(dev);

        chip_priv->buf[0] = tpm_register;
        memcpy(chip_priv->buf + 1, tpm_data, tpm_size);

        return dm_i2c_write(dev, 0, chip_priv->buf, tpm_size + 1);
}

/*
* st33zp24_i2c_read8_reg
* Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
* @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 else an error code.
*/
static int st33zp24_i2c_read8_reg(struct udevice *dev, u8 tpm_register,
                                  u8 *tpm_data, size_t tpm_size)
{
        int status;
        u8 data;

        data = TPM_DUMMY_BYTE;
        status = st33zp24_i2c_write8_reg(dev, tpm_register, &data, 1);
        if (status < 0)
                return status;

        return dm_i2c_read(dev, 0, tpm_data, tpm_size);
}

/*
 * st33zp24_i2c_write
 * Send byte to the TIS register according to the ST33ZP24 I2C 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: number of byte written successfully: should be one if success.
 */
static int st33zp24_i2c_write(struct udevice *dev, u8 tpm_register,
                              const u8 *tpm_data, size_t tpm_size)
{
        return st33zp24_i2c_write8_reg(dev, tpm_register | TPM_WRITE_DIRECTION,
                                       tpm_data, tpm_size);
}

/*
 * st33zp24_i2c_read
 * Recv byte from the TIS register according to the ST33ZP24 I2C 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_i2c_read(struct udevice *dev, u8 tpm_register,
                             u8 *tpm_data, size_t tpm_size)
{
        return st33zp24_i2c_read8_reg(dev, tpm_register, tpm_data, tpm_size);
}

/*
 * st33zp24_i2c_release_locality release the active locality
 * @param: chip, the tpm chip description.
 */
static void st33zp24_i2c_release_locality(struct udevice *dev)
{
        u8 data = TPM_ACCESS_ACTIVE_LOCALITY;

        st33zp24_i2c_write(dev, TPM_ACCESS, &data, 1);
}

/*
 * st33zp24_i2c_check_locality if the locality is active
 * @param: chip, the tpm chip description
 * @return: the active locality or -EACCES.
 */
static int st33zp24_i2c_check_locality(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        u8 data;
        u8 status;

        status = st33zp24_i2c_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_i2c_request_locality request the TPM locality
 * @param: chip, the chip description
 * @return: the active locality or negative value.
 */
static int st33zp24_i2c_request_locality(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        unsigned long start, stop;
        long ret;
        u8 data;

        if (st33zp24_i2c_check_locality(dev) == chip->locality)
                return chip->locality;

        data = TPM_ACCESS_REQUEST_USE;
        ret = st33zp24_i2c_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_i2c_check_locality(dev) >= 0)
                        return chip->locality;
                udelay(TPM_TIMEOUT_MS * 1000);
        } while  (get_timer(start) < stop);

        return -EACCES;
}

/*
 * st33zp24_i2c_status return the TPM_STS register
 * @param: chip, the tpm chip description
 * @return: the TPM_STS register value.
 */
static u8 st33zp24_i2c_status(struct udevice *dev)
{
        u8 data;

        st33zp24_i2c_read(dev, TPM_STS, &data, 1);

        return data;
}

/*
 * st33zp24_i2c_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_i2c_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_i2c_read(dev, tpm_reg, &temp, 1);
                if (status < 0)
                        return -EBUSY;

                tpm_reg = TPM_STS + 2;
                burstcnt = temp;
                status = st33zp24_i2c_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_i2c_cancel, cancel the current command execution or
 * set STS to COMMAND READY.
 * @param: chip, tpm_chip description.
 */
static void st33zp24_i2c_cancel(struct udevice *dev)
{
        u8 data;

        data = TPM_STS_COMMAND_READY;
        st33zp24_i2c_write(dev, TPM_STS, &data, 1);
}

/*
 * st33zp24_i2c_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_i2c_wait_for_stat(struct udevice *dev, u8 mask,
                                      unsigned long timeout, int *status)
{
        unsigned long start, stop;

        /* Check current status */
        *status = st33zp24_i2c_status(dev);
        if ((*status & mask) == mask)
                return 0;

        start = get_timer(0);
        stop = timeout;
        do {
                udelay(TPM_TIMEOUT_MS * 1000);
                *status = st33zp24_i2c_status(dev);
                if ((*status & mask) == mask)
                        return 0;
        } while (get_timer(start) < stop);

        return -ETIME;
}

/*
 * st33zp24_i2c_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_i2c_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_i2c_wait_for_stat(dev, TPM_STS_DATA_AVAIL | TPM_STS_VALID,
                                chip->timeout_c, &status) == 0) {
                burstcnt = st33zp24_i2c_get_burstcount(dev);
                if (burstcnt < 0)
                        return burstcnt;
                len = min_t(int, burstcnt, count - size);
                ret = st33zp24_i2c_read(dev, TPM_DATA_FIFO, buf + size, len);
                if (ret < 0)
                        return ret;

                size += len;
        }

        return size;
}

/*
 * st33zp24_i2c_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_i2c_recv(struct udevice *dev, u8 *buf, size_t count)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        int size, expected;

        if (!chip)
                return -ENODEV;

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

        size = st33zp24_i2c_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) {
                size = -EIO;
                goto out;
        }

        size += st33zp24_i2c_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_i2c_cancel(dev);
        st33zp24_i2c_release_locality(dev);

        return size;
}

/*
 * st33zp24_i2c_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_i2c_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_i2c_request_locality(dev);
        if (ret < 0)
                return ret;

        tpm_stat = st33zp24_i2c_status(dev);
        if ((tpm_stat & TPM_STS_COMMAND_READY) == 0) {
                st33zp24_i2c_cancel(dev);
                if (st33zp24_i2c_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_i2c_get_burstcount(dev);
                if (burstcnt < 0)
                        return burstcnt;

                size = min_t(int, len - i - 1, burstcnt);
                ret = st33zp24_i2c_write(dev, TPM_DATA_FIFO, buf + i, size);
                if (ret < 0)
                        goto out_err;

                i += size;
        }

        tpm_stat = st33zp24_i2c_status(dev);
        if ((tpm_stat & TPM_STS_DATA_EXPECT) == 0) {
                ret = -EIO;
                goto out_err;
        }

        ret = st33zp24_i2c_write(dev, TPM_DATA_FIFO, buf + len - 1, 1);
        if (ret < 0)
                goto out_err;

        tpm_stat = st33zp24_i2c_status(dev);
        if ((tpm_stat & TPM_STS_DATA_EXPECT) != 0) {
                ret = -EIO;
                goto out_err;
        }

        data = TPM_STS_GO;
        ret = st33zp24_i2c_write(dev, TPM_STS, &data, 1);
        if (ret < 0)
                goto out_err;

        return len;

out_err:
        st33zp24_i2c_cancel(dev);
        st33zp24_i2c_release_locality(dev);

        return ret;
}

static int st33zp24_i2c_cleanup(struct udevice *dev)
{
        st33zp24_i2c_cancel(dev);
        /*
         * The TPM needs some time to clean up here,
         * so we sleep rather than keeping the bus busy
         */
        mdelay(2);
        st33zp24_i2c_release_locality(dev);

        return 0;
}

static int st33zp24_i2c_init(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(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;

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

        return 0;
}

static int st33zp24_i2c_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_i2c_init(dev);
        if (rc < 0)
                chip->is_open = 0;

        return rc;
}

static int st33zp24_i2c_close(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);

        if (chip->is_open) {
                st33zp24_i2c_release_locality(dev);
                chip->is_open = 0;
                chip->vend_dev = 0;
        }

        return 0;
}

static int st33zp24_i2c_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);
}

static const struct tpm_ops st33zp24_i2c_tpm_ops = {
        .open = st33zp24_i2c_open,
        .close = st33zp24_i2c_close,
        .recv = st33zp24_i2c_recv,
        .send = st33zp24_i2c_send,
        .cleanup = st33zp24_i2c_cleanup,
        .get_desc = st33zp24_i2c_get_desc,
};

static int st33zp24_i2c_probe(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);

        /* Default timeouts */
        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;

        i2c_set_chip_offset_len(dev, 0);

        debug("ST33ZP24 I2C TPM from STMicroelectronics found\n");

        return 0;
}

static int st33zp24_i2c_remove(struct udevice *dev)
{
        st33zp24_i2c_release_locality(dev);

        return 0;
}

static const struct udevice_id st33zp24_i2c_ids[] = {
        { .compatible = "st,st33zp24-i2c" },
        { }
};

U_BOOT_DRIVER(st33zp24_i2c) = {
        .name   = "st33zp24-i2c",
        .id     = UCLASS_TPM,
        .of_match = of_match_ptr(st33zp24_i2c_ids),
        .probe  = st33zp24_i2c_probe,
        .remove = st33zp24_i2c_remove,
        .ops = &st33zp24_i2c_tpm_ops,
        .priv_auto_alloc_size = sizeof(struct tpm_chip),
};