/*
 * 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
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

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

#include "tpm_private.h"

DECLARE_GLOBAL_DATA_PTR;

/* Address of the TPM on the I2C bus */
#define TPM_I2C_ADDR            0x20

/* Max buffer size supported by our tpm */
#define TPM_DEV_BUFSIZE         1260

/* Max number of iterations after i2c NAK */
#define MAX_COUNT               3

/*
 * Max number of iterations after i2c NAK for 'long' commands
 *
 * We need this especially for sending TPM_READY, since the cleanup after the
 * transtion to the ready state may take some time, but it is unpredictable
 * how long it will take.
 */
#define MAX_COUNT_LONG          50

#define SLEEP_DURATION          60      /* in usec */
#define SLEEP_DURATION_LONG     210     /* in usec */

#define TPM_HEADER_SIZE         10

/*
 * Expected value for DIDVID register
 *
 * The only device the system knows about at this moment is Infineon slb9635.
 */
#define TPM_TIS_I2C_DID_VID     0x000b15d1L

enum tis_access {
        TPM_ACCESS_VALID                = 0x80,
        TPM_ACCESS_ACTIVE_LOCALITY      = 0x20,
        TPM_ACCESS_REQUEST_PENDING      = 0x04,
        TPM_ACCESS_REQUEST_USE          = 0x02,
};

enum tis_status {
        TPM_STS_VALID                   = 0x80,
        TPM_STS_COMMAND_READY           = 0x40,
        TPM_STS_GO                      = 0x20,
        TPM_STS_DATA_AVAIL              = 0x10,
        TPM_STS_DATA_EXPECT             = 0x08,
};

enum tis_defaults {
        TIS_SHORT_TIMEOUT               = 750,  /* ms */
        TIS_LONG_TIMEOUT                = 2000, /* ms */
};

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

enum i2c_chip_type {
        SLB9635,
        SLB9645,
        UNKNOWN,
};

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))

/* Structure to store I2C TPM specific stuff */
struct tpm_dev {
        uint addr;
        u8 buf[TPM_DEV_BUFSIZE + sizeof(u8)];  /* Max buffer size + addr */
        enum i2c_chip_type chip_type;
};

static struct tpm_dev tpm_dev = {
        .addr = TPM_I2C_ADDR
};

static struct tpm_dev tpm_dev;

/*
 * iic_tpm_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 iic_tpm_read(u8 addr, u8 *buffer, size_t len)
{
        int rc;
        int count;
        uint32_t addrbuf = addr;

        if ((tpm_dev.chip_type == SLB9635) || (tpm_dev.chip_type == UNKNOWN)) {
                /* slb9635 protocol should work in both cases */
                for (count = 0; count < MAX_COUNT; count++) {
                        rc = i2c_write(tpm_dev.addr, 0, 0,
                                       (uchar *)&addrbuf, 1);
                        if (rc == 0)
                                break;  /* Success, break to skip sleep */
                        udelay(SLEEP_DURATION);
                }
                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);
                        rc = i2c_read(tpm_dev.addr, 0, 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 = i2c_read(tpm_dev.addr, addr, 1, buffer, len);
                        if (rc == 0)
                                break;  /* break here to skip sleep */
                        udelay(SLEEP_DURATION);
                }
        }

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

        return 0;
}

static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t len,
                unsigned int sleep_time, u8 max_count)
{
        int rc = 0;
        int count;

        /* Prepare send buffer */
        tpm_dev.buf[0] = addr;
        memcpy(&(tpm_dev.buf[1]), buffer, len);

        for (count = 0; count < max_count; count++) {
                rc = i2c_write(tpm_dev.addr, 0, 0, tpm_dev.buf, len + 1);
                if (rc == 0)
                        break;  /* Success, break to skip sleep */
                udelay(sleep_time);
        }

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

        return 0;
}

/*
 * iic_tpm_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 iic_tpm_write_generic function.
 *
 * Return -EIO on error, 0 on success
 */
static int iic_tpm_write(u8 addr, u8 *buffer, size_t len)
{
        return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION,
                        MAX_COUNT);
}

/*
 * This function is needed especially for the cleanup situation after
 * sending TPM_READY
 */
static int iic_tpm_write_long(u8 addr, u8 *buffer, size_t len)
{
        return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION_LONG,
                        MAX_COUNT_LONG);
}

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

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

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

        return -1;
}

static void release_locality(struct tpm_chip *chip, int loc, int force)
{
        const u8 mask = TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID;
        u8 buf;

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

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

static int request_locality(struct tpm_chip *chip, int loc)
{
        unsigned long start, stop;
        u8 buf = TPM_ACCESS_REQUEST_USE;

        if (check_locality(chip, loc) >= 0)
                return loc;  /* We already have the locality */

        iic_tpm_write(TPM_ACCESS(loc), &buf, 1);

        /* Wait for burstcount */
        start = get_timer(0);
        stop = chip->vendor.timeout_a;
        do {
                if (check_locality(chip, loc) >= 0)
                        return loc;
                udelay(TPM_TIMEOUT * 1000);
        } while (get_timer(start) < stop);

        return -1;
}

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

        if (iic_tpm_read(TPM_STS(chip->vendor.locality), &buf, 1) < 0)
                return 0;
        else
                return buf;
}

static void tpm_tis_i2c_ready(struct tpm_chip *chip)
{
        /* This causes the current command to be aborted */
        u8 buf = TPM_STS_COMMAND_READY;

        iic_tpm_write_long(TPM_STS(chip->vendor.locality), &buf, 1);
}

static ssize_t get_burstcount(struct tpm_chip *chip)
{
        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->vendor.timeout_d;
        do {
                /* Note: STS is little endian */
                addr = TPM_STS(chip->vendor.locality) + 1;
                if (iic_tpm_read(addr, buf, 3) < 0)
                        burstcnt = 0;
                else
                        burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];

                if (burstcnt)
                        return burstcnt;
                udelay(TPM_TIMEOUT * 1000);
        } while (get_timer(start) < stop);

        return -EBUSY;
}

static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
                int *status)
{
        unsigned long start, stop;

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

        start = get_timer(0);
        stop = timeout;
        do {
                udelay(TPM_TIMEOUT * 1000);
                *status = tpm_tis_i2c_status(chip);
                if ((*status & mask) == mask)
                        return 0;
        } while (get_timer(start) < stop);

        return -ETIME;
}

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

        while (size < count) {
                burstcnt = get_burstcount(chip);

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

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

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

        return size;
}

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

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

        /* Read first 10 bytes, including tag, paramsize, and result */
        size = recv_data(chip, buf, TPM_HEADER_SIZE);
        if (size < TPM_HEADER_SIZE) {
                error("Unable to read header\n");
                goto out;
        }

        expected = get_unaligned_be32(buf + TPM_RSP_SIZE_BYTE);
        if ((size_t)expected > count) {
                size = -EIO;
                goto out;
        }

        size += recv_data(chip, &buf[TPM_HEADER_SIZE],
                        expected - TPM_HEADER_SIZE);
        if (size < expected) {
                error("Unable to read remainder of result\n");
                size = -ETIME;
                goto out;
        }

        wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status);
        if (status & TPM_STS_DATA_AVAIL) {  /* Retry? */
                error("Error left over data\n");
                size = -EIO;
                goto out;
        }

out:
        tpm_tis_i2c_ready(chip);
        /*
         * The TPM needs some time to clean up here,
         * so we sleep rather than keeping the bus busy
         */
        udelay(2000);
        release_locality(chip, chip->vendor.locality, 0);

        return size;
}

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

        if (len > TPM_DEV_BUFSIZE)
                return -E2BIG;  /* Command is too long for our tpm, sorry */

        if (request_locality(chip, 0) < 0)
                return -EBUSY;

        status = tpm_tis_i2c_status(chip);
        if ((status & TPM_STS_COMMAND_READY) == 0) {
                tpm_tis_i2c_ready(chip);
                if (wait_for_stat(chip, TPM_STS_COMMAND_READY,
                                  chip->vendor.timeout_b, &status) < 0) {
                        rc = -ETIME;
                        goto out_err;
                }
        }

        burstcnt = get_burstcount(chip);

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

        while (count < len - 1) {
                if (burstcnt > len - 1 - count)
                        burstcnt = len - 1 - count;

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

                rc = iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality),
                                &(buf[count]), burstcnt);
                if (rc == 0)
                        count += burstcnt;
                else {
                        retry++;
                        wait_for_stat(chip, TPM_STS_VALID,
                                      chip->vendor.timeout_c, &status);

                        if ((status & TPM_STS_DATA_EXPECT) == 0) {
                                rc = -EIO;
                                goto out_err;
                        }
                }
        }

        /* Write last byte */
        iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality), &(buf[count]), 1);
        wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status);
        if ((status & TPM_STS_DATA_EXPECT) != 0) {
                rc = -EIO;
                goto out_err;
        }

        /* Go and do it */
        iic_tpm_write(TPM_STS(chip->vendor.locality), &sts, 1);

        return len;

out_err:
        tpm_tis_i2c_ready(chip);
        /*
         * The TPM needs some time to clean up here,
         * so we sleep rather than keeping the bus busy
         */
        udelay(2000);
        release_locality(chip, chip->vendor.locality, 0);

        return rc;
}

static struct tpm_vendor_specific tpm_tis_i2c = {
        .status = tpm_tis_i2c_status,
        .recv = tpm_tis_i2c_recv,
        .send = tpm_tis_i2c_send,
        .cancel = tpm_tis_i2c_ready,
        .req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
        .req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
        .req_canceled = TPM_STS_COMMAND_READY,
};


static enum i2c_chip_type tpm_vendor_chip_type(void)
{
#ifdef CONFIG_OF_CONTROL
        const void *blob = gd->fdt_blob;

        if (fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9645_TPM) >= 0)
                return SLB9645;

        if (fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9635_TPM) >= 0)
                return SLB9635;
#endif
        return UNKNOWN;
}

/* Initialisation of i2c tpm */
int tpm_vendor_init(uint32_t dev_addr)
{
        u32 vendor;
        u32 expected_did_vid;
        uint old_addr;
        int rc = 0;
        struct tpm_chip *chip;

        old_addr = tpm_dev.addr;
        if (dev_addr != 0)
                tpm_dev.addr = dev_addr;

        tpm_dev.chip_type = tpm_vendor_chip_type();

        chip = tpm_register_hardware(&tpm_tis_i2c);
        if (chip < 0) {
                rc = -ENODEV;
                goto out_err;
        }

        /* Disable interrupts (not supported) */
        chip->vendor.irq = 0;

        /* Default timeouts */
        chip->vendor.timeout_a = TIS_SHORT_TIMEOUT;
        chip->vendor.timeout_b = TIS_LONG_TIMEOUT;
        chip->vendor.timeout_c = TIS_SHORT_TIMEOUT;
        chip->vendor.timeout_d = TIS_SHORT_TIMEOUT;

        if (request_locality(chip, 0) < 0) {
                rc = -ENODEV;
                goto out_err;
        }

        /* Read four bytes from DID_VID register */
        if (iic_tpm_read(TPM_DID_VID(0), (uchar *)&vendor, 4) < 0) {
                rc = -EIO;
                goto out_release;
        }

        if (tpm_dev.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 (tpm_dev.chip_type != UNKNOWN && vendor != expected_did_vid) {
                error("Vendor id did not match! ID was %08x\n", vendor);
                rc = -ENODEV;
                goto out_release;
        }

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

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

        return 0;

out_release:
        release_locality(chip, 0, 1);

out_err:
        tpm_dev.addr = old_addr;
        return rc;
}

void tpm_vendor_cleanup(struct tpm_chip *chip)
{
        release_locality(chip, chip->vendor.locality, 1);
}