/*
 * Copyright (C) 2011 Infineon Technologies
 *
 * Authors:
 * Peter Huewe <huewe.external@infineon.com>
 *
 * Description:
 * 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 1.2, revision 1.0 and the
 * Infineon I2C Protocol Stack Specification v0.20.
 *
 * It is based on the Linux kernel driver tpm.c from Leendert van
 * Dorn, Dave Safford, Reiner Sailer, and Kyleen Hall.
 *
 * Version: 2.1.1
 *
 * SPDX-License-Identifier:     GPL-2.0
 */

#include <common.h>
#include <dm.h>
#include <fdtdec.h>
#include <i2c.h>
#include <tpm.h>
#include <asm-generic/errno.h>
#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/unaligned/be_byteshift.h>

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

DECLARE_GLOBAL_DATA_PTR;

enum i2c_chip_type {
        SLB9635,
        SLB9645,
        UNKNOWN,
};

/* expected value for DIDVID register */
#define TPM_TIS_I2C_DID_VID_9635 0x000b15d1L
#define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L

static const char * const chip_name[] = {
        [SLB9635] = "slb9635tt",
        [SLB9645] = "slb9645tt",
        [UNKNOWN] = "unknown/fallback to slb9635",
};

#define TPM_ACCESS(l)                   (0x0000 | ((l) << 4))
#define TPM_STS(l)                      (0x0001 | ((l) << 4))
#define TPM_DATA_FIFO(l)                (0x0005 | ((l) << 4))
#define TPM_DID_VID(l)                  (0x0006 | ((l) << 4))

/*
 * tpm_tis_i2c_read() - read from TPM register
 * @addr: register address to read from
 * @buffer: provided by caller
 * @len: number of bytes to read
 *
 * Read len bytes from TPM register and put them into
 * buffer (little-endian format, i.e. first byte is put into buffer[0]).
 *
 * NOTE: TPM is big-endian for multi-byte values. Multi-byte
 * values have to be swapped.
 *
 * Return -EIO on error, 0 on success.
 */
static int tpm_tis_i2c_read(struct udevice *dev, u8 addr, u8 *buffer,
                            size_t len)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        int rc;
        int count;
        uint32_t addrbuf = addr;

        if ((chip->chip_type == SLB9635) || (chip->chip_type == UNKNOWN)) {
                /* slb9635 protocol should work in both cases */
                for (count = 0; count < MAX_COUNT; count++) {
                        rc = dm_i2c_write(dev, 0, (uchar *)&addrbuf, 1);
                        if (rc == 0)
                                break;  /* Success, break to skip sleep */
                        udelay(SLEEP_DURATION_US);
                }
                if (rc)
                        return rc;

                /* After the TPM has successfully received the register address
                 * it needs some time, thus we're sleeping here again, before
                 * retrieving the data
                 */
                for (count = 0; count < MAX_COUNT; count++) {
                        udelay(SLEEP_DURATION_US);
                        rc = dm_i2c_read(dev, 0, buffer, len);
                        if (rc == 0)
                                break;  /* success, break to skip sleep */
                }
        } else {
                /*
                 * Use a combined read for newer chips.
                 * Unfortunately the smbus functions are not suitable due to
                 * the 32 byte limit of the smbus.
                 * Retries should usually not be needed, but are kept just to
                 * be safe on the safe side.
                 */
                for (count = 0; count < MAX_COUNT; count++) {
                        rc = dm_i2c_read(dev, addr, buffer, len);
                        if (rc == 0)
                                break;  /* break here to skip sleep */
                        udelay(SLEEP_DURATION_US);
                }
        }

        /* Take care of 'guard time' */
        udelay(SLEEP_DURATION_US);
        if (rc)
                return rc;

        return 0;
}

static int tpm_tis_i2c_write_generic(struct udevice *dev, u8 addr,
                                     const u8 *buffer, size_t len,
                                     unsigned int sleep_time_us, u8 max_count)
{
        struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
        struct tpm_chip *chip = dev_get_priv(dev);
        int rc = 0;
        int count;

        if (chip->chip_type == SLB9635) {
                /* Prepare send buffer to include the address */
                priv->buf[0] = addr;
                memcpy(&(priv->buf[1]), buffer, len);
                buffer = priv->buf;
                len++;
                addr = 0;
        }

        for (count = 0; count < max_count; count++) {
                rc = dm_i2c_write(dev, addr, buffer, len);
                if (rc == 0)
                        break;  /* Success, break to skip sleep */
                udelay(sleep_time_us);
        }

        /* take care of 'guard time' */
        udelay(sleep_time_us);
        if (rc)
                return rc;

        return 0;
}

/*
 * tpm_tis_i2c_write() - write to TPM register
 * @addr: register address to write to
 * @buffer: containing data to be written
 * @len: number of bytes to write
 *
 * Write len bytes from provided buffer to TPM register (little
 * endian format, i.e. buffer[0] is written as first byte).
 *
 * NOTE: TPM is big-endian for multi-byte values. Multi-byte
 * values have to be swapped.
 *
 * NOTE: use this function instead of the tpm_tis_i2c_write_generic function.
 *
 * Return -EIO on error, 0 on success
 */
static int tpm_tis_i2c_write(struct udevice *dev, u8 addr, const u8 *buffer,
                             size_t len)
{
        return tpm_tis_i2c_write_generic(dev, addr, buffer, len,
                                         SLEEP_DURATION_US, MAX_COUNT);
}

/*
 * This function is needed especially for the cleanup situation after
 * sending TPM_READY
 */
static int tpm_tis_i2c_write_long(struct udevice *dev, u8 addr, u8 *buffer,
                                  size_t len)
{
        return tpm_tis_i2c_write_generic(dev, addr, buffer, len,
                                         SLEEP_DURATION_LONG_US,
                                         MAX_COUNT_LONG);
}

static int tpm_tis_i2c_check_locality(struct udevice *dev, int loc)
{
        const u8 mask = TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID;
        struct tpm_chip *chip = dev_get_priv(dev);
        u8 buf;
        int rc;

        rc = tpm_tis_i2c_read(dev, TPM_ACCESS(loc), &buf, 1);
        if (rc < 0)
                return rc;

        if ((buf & mask) == mask) {
                chip->locality = loc;
                return loc;
        }

        return -ENOENT;
}

static void tpm_tis_i2c_release_locality(struct udevice *dev, int loc,
                                         int force)
{
        const u8 mask = TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID;
        u8 buf;

        if (tpm_tis_i2c_read(dev, TPM_ACCESS(loc), &buf, 1) < 0)
                return;

        if (force || (buf & mask) == mask) {
                buf = TPM_ACCESS_ACTIVE_LOCALITY;
                tpm_tis_i2c_write(dev, TPM_ACCESS(loc), &buf, 1);
        }
}

static int tpm_tis_i2c_request_locality(struct udevice *dev, int loc)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        unsigned long start, stop;
        u8 buf = TPM_ACCESS_REQUEST_USE;
        int rc;

        rc = tpm_tis_i2c_check_locality(dev, loc);
        if (rc >= 0) {
                debug("%s: Already have locality\n", __func__);
                return loc;  /* We already have the locality */
        } else if (rc != -ENOENT) {
                debug("%s: Failed to get locality: %d\n", __func__, rc);
                return rc;
        }

        rc = tpm_tis_i2c_write(dev, TPM_ACCESS(loc), &buf, 1);
        if (rc) {
                debug("%s: Failed to write to TPM: %d\n", __func__, rc);
                return rc;
        }

        /* Wait for burstcount */
        start = get_timer(0);
        stop = chip->timeout_a;
        do {
                rc = tpm_tis_i2c_check_locality(dev, loc);
                if (rc >= 0) {
                        debug("%s: Have locality\n", __func__);
                        return loc;
                } else if (rc != -ENOENT) {
                        debug("%s: Failed to get locality: %d\n", __func__, rc);
                        return rc;
                }
                mdelay(TPM_TIMEOUT_MS);
        } while (get_timer(start) < stop);
        debug("%s: Timeout getting locality: %d\n", __func__, rc);

        return rc;
}

static u8 tpm_tis_i2c_status(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        /* NOTE: Since i2c read may fail, return 0 in this case --> time-out */
        u8 buf;

        if (tpm_tis_i2c_read(dev, TPM_STS(chip->locality), &buf, 1) < 0)
                return 0;
        else
                return buf;
}

static int tpm_tis_i2c_ready(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        int rc;

        /* This causes the current command to be aborted */
        u8 buf = TPM_STS_COMMAND_READY;

        debug("%s\n", __func__);
        rc = tpm_tis_i2c_write_long(dev, TPM_STS(chip->locality), &buf, 1);
        if (rc)
                debug("%s: rc=%d\n", __func__, rc);

        return rc;
}

static ssize_t tpm_tis_i2c_get_burstcount(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        unsigned long start, stop;
        ssize_t burstcnt;
        u8 addr, buf[3];

        /* Wait for burstcount */
        /* XXX: Which timeout value? Spec has 2 answers (c & d) */
        start = get_timer(0);
        stop = chip->timeout_d;
        do {
                /* Note: STS is little endian */
                addr = TPM_STS(chip->locality) + 1;
                if (tpm_tis_i2c_read(dev, addr, buf, 3) < 0)
                        burstcnt = 0;
                else
                        burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];

                if (burstcnt)
                        return burstcnt;
                mdelay(TPM_TIMEOUT_MS);
        } while (get_timer(start) < stop);

        return -EBUSY;
}

static int tpm_tis_i2c_wait_for_stat(struct udevice *dev, u8 mask,
                                     unsigned long timeout, int *status)
{
        unsigned long start, stop;

        /* Check current status */
        *status = tpm_tis_i2c_status(dev);
        if ((*status & mask) == mask)
                return 0;

        start = get_timer(0);
        stop = timeout;
        do {
                mdelay(TPM_TIMEOUT_MS);
                *status = tpm_tis_i2c_status(dev);
                if ((*status & mask) == mask)
                        return 0;
        } while (get_timer(start) < stop);

        return -ETIMEDOUT;
}

static int tpm_tis_i2c_recv_data(struct udevice *dev, u8 *buf, size_t count)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        size_t size = 0;
        ssize_t burstcnt;
        int rc;

        while (size < count) {
                burstcnt = tpm_tis_i2c_get_burstcount(dev);

                /* burstcount < 0 -> tpm is busy */
                if (burstcnt < 0)
                        return burstcnt;

                /* Limit received data to max left */
                if (burstcnt > (count - size))
                        burstcnt = count - size;

                rc = tpm_tis_i2c_read(dev, TPM_DATA_FIFO(chip->locality),
                                      &(buf[size]), burstcnt);
                if (rc == 0)
                        size += burstcnt;
        }

        return size;
}

static int tpm_tis_i2c_recv(struct udevice *dev, u8 *buf, size_t count)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        int size = 0;
        int expected, status;
        int rc;

        status = tpm_tis_i2c_status(dev);
        if (status == TPM_STS_COMMAND_READY)
                return -EINTR;
        if ((status & (TPM_STS_DATA_AVAIL | TPM_STS_VALID)) !=
            (TPM_STS_DATA_AVAIL | TPM_STS_VALID))
                return -EAGAIN;

        debug("...got it;\n");

        /* Read first 10 bytes, including tag, paramsize, and result */
        size = tpm_tis_i2c_recv_data(dev, buf, TPM_HEADER_SIZE);
        if (size < TPM_HEADER_SIZE) {
                debug("Unable to read header\n");
                return size < 0 ? size : -EIO;
        }

        expected = get_unaligned_be32(buf + TPM_RSP_SIZE_BYTE);
        if ((size_t)expected > count) {
                debug("Error size=%x, expected=%x, count=%x\n", size, expected,
                      count);
                return -ENOSPC;
        }

        size += tpm_tis_i2c_recv_data(dev, &buf[TPM_HEADER_SIZE],
                                      expected - TPM_HEADER_SIZE);
        if (size < expected) {
                debug("Unable to read remainder of result\n");
                return -ETIMEDOUT;
        }

        rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_VALID, chip->timeout_c,
                                       &status);
        if (rc)
                return rc;
        if (status & TPM_STS_DATA_AVAIL) {  /* Retry? */
                debug("Error left over data\n");
                return -EIO;
        }

        return size;
}

static int tpm_tis_i2c_send(struct udevice *dev, const u8 *buf, size_t len)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        int rc, status;
        size_t burstcnt;
        size_t count = 0;
        int retry = 0;
        u8 sts = TPM_STS_GO;

        debug("%s: len=%d\n", __func__, len);
        if (len > TPM_DEV_BUFSIZE)
                return -E2BIG;  /* Command is too long for our tpm, sorry */

        if (tpm_tis_i2c_request_locality(dev, 0) < 0)
                return -EBUSY;

        status = tpm_tis_i2c_status(dev);
        if ((status & TPM_STS_COMMAND_READY) == 0) {
                rc = tpm_tis_i2c_ready(dev);
                if (rc)
                        return rc;
                rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_COMMAND_READY,
                                               chip->timeout_b, &status);
                if (rc)
                        return rc;
        }

        burstcnt = tpm_tis_i2c_get_burstcount(dev);

        /* burstcount < 0 -> tpm is busy */
        if (burstcnt < 0)
                return burstcnt;

        while (count < len) {
                udelay(300);
                if (burstcnt > len - count)
                        burstcnt = len - count;

#ifdef CONFIG_TPM_TIS_I2C_BURST_LIMITATION
                if (retry && burstcnt > CONFIG_TPM_TIS_I2C_BURST_LIMITATION_LEN)
                        burstcnt = CONFIG_TPM_TIS_I2C_BURST_LIMITATION_LEN;
#endif /* CONFIG_TPM_TIS_I2C_BURST_LIMITATION */

                rc = tpm_tis_i2c_write(dev, TPM_DATA_FIFO(chip->locality),
                                       &(buf[count]), burstcnt);
                if (rc == 0)
                        count += burstcnt;
                else {
                        debug("%s: error\n", __func__);
                        if (retry++ > 10)
                                return -EIO;
                        rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_VALID,
                                                       chip->timeout_c,
                                                       &status);
                        if (rc)
                                return rc;

                        if ((status & TPM_STS_DATA_EXPECT) == 0)
                                return -EIO;
                }
        }

        /* Go and do it */
        rc = tpm_tis_i2c_write(dev, TPM_STS(chip->locality), &sts, 1);
        if (rc < 0)
                return rc;
        debug("%s: done, rc=%d\n", __func__, rc);

        return len;
}

static int tpm_tis_i2c_cleanup(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);

        tpm_tis_i2c_ready(dev);
        /*
         * The TPM needs some time to clean up here,
         * so we sleep rather than keeping the bus busy
         */
        mdelay(2);
        tpm_tis_i2c_release_locality(dev, chip->locality, 0);

        return 0;
}

static int tpm_tis_i2c_init(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        u32 vendor;
        u32 expected_did_vid;
        int rc;

        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;

        rc = tpm_tis_i2c_request_locality(dev, 0);
        if (rc < 0)
                return rc;

        /* Read four bytes from DID_VID register */
        if (tpm_tis_i2c_read(dev, TPM_DID_VID(0), (uchar *)&vendor, 4) < 0) {
                tpm_tis_i2c_release_locality(dev, 0, 1);
                return -EIO;
        }

        if (chip->chip_type == SLB9635) {
                vendor = be32_to_cpu(vendor);
                expected_did_vid = TPM_TIS_I2C_DID_VID_9635;
        } else {
                /* device id and byte order has changed for newer i2c tpms */
                expected_did_vid = TPM_TIS_I2C_DID_VID_9645;
        }

        if (chip->chip_type != UNKNOWN && vendor != expected_did_vid) {
                error("Vendor id did not match! ID was %08x\n", vendor);
                return -ENODEV;
        }

        chip->vend_dev = vendor;
        debug("1.2 TPM (chip type %s device-id 0x%X)\n",
              chip_name[chip->chip_type], vendor >> 16);

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

        return 0;
}

static int tpm_tis_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 = tpm_tis_i2c_init(dev);
        if (rc < 0)
                chip->is_open = 0;

        return rc;
}

static int tpm_tis_i2c_close(struct udevice *dev)
{
        struct tpm_chip *chip = dev_get_priv(dev);

        if (chip->is_open) {
                tpm_tis_i2c_release_locality(dev, chip->locality, 1);
                chip->is_open = 0;
                chip->vend_dev = 0;
        }

        return 0;
}

static int tpm_tis_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",
                        chip_name[chip->chip_type],
                        chip->vend_dev >> 16);
}

static int tpm_tis_i2c_probe(struct udevice *dev)
{
        struct tpm_chip_priv *uc_priv = dev_get_uclass_priv(dev);
        struct tpm_chip *chip = dev_get_priv(dev);

        chip->chip_type = dev_get_driver_data(dev);

        /* TODO: These need to be checked and tuned */
        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;

        return 0;
}

static const struct tpm_ops tpm_tis_i2c_ops = {
        .open           = tpm_tis_i2c_open,
        .close          = tpm_tis_i2c_close,
        .get_desc       = tpm_tis_get_desc,
        .send           = tpm_tis_i2c_send,
        .recv           = tpm_tis_i2c_recv,
        .cleanup        = tpm_tis_i2c_cleanup,
};

static const struct udevice_id tpm_tis_i2c_ids[] = {
        { .compatible = "infineon,slb9635tt", .data = SLB9635 },
        { .compatible = "infineon,slb9645tt", .data = SLB9645 },
        { }
};

U_BOOT_DRIVER(tpm_tis_i2c) = {
        .name   = "tpm_tis_infineon",
        .id     = UCLASS_TPM,
        .of_match = tpm_tis_i2c_ids,
        .ops    = &tpm_tis_i2c_ops,
        .probe  = tpm_tis_i2c_probe,
        .priv_auto_alloc_size = sizeof(struct tpm_chip),
};