io/tpm/tpm.c

	tpm.c revision b693132f48f19b8c1bd613e914faf3589565cb57
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * TPM 1.2 Driver for the TPMs that follow TIS v1.2
 */

#include <sys/devops.h>     /* used by dev_ops */
#include <sys/conf.h>       /* used by dev_ops,cb_ops */
#include <sys/modctl.h>     /* for _init,_info,_fini,mod_* */
#include <sys/ddi.h>        /* used by all entry points */
#include <sys/sunddi.h>     /* used by all entry points */
#include <sys/cmn_err.h>    /* used for debug outputs */
#include <sys/types.h>      /* used by prop_op, ddi_prop_op */

#include <sys/file.h>       /* used by open, close */
#include <sys/errno.h>      /* used by open,close,read,write */
#include <sys/open.h>       /* used by open,close,read,write */
#include <sys/cred.h>       /* used by open,close,read */
#include <sys/uio.h>        /* used by read */
#include <sys/stat.h>       /* defines S_IFCHR */

#include <sys/byteorder.h>  /* for ntohs, ntohl, htons, htonl */

#include <tss/platform.h>   /* from SUNWtss */
#include <tss/tpm.h>        /* from SUNWtss */

#include "tpm_tis.h"
#include "tpm_ddi.h"
#include "tpm_duration.h"

#define TPM_HEADER_SIZE 10
typedef enum {
    TPM_TAG_OFFSET = 0,
    TPM_PARAMSIZE_OFFSET = 2,
    TPM_RETURN_OFFSET = 6,
    TPM_COMMAND_CODE_OFFSET = 6,
} TPM_HEADER_OFFSET_T;

/*
 * This is to address some TPMs that does not report the correct duration
 * and timeouts.  In our experience with the production TPMs, we encountered
 * time errors such as GetCapability command from TPM reporting the timeout
 * and durations in milliseconds rather than microseconds.  Some other TPMs
 * report the value 0's
 *
 * Short Duration is based on section 11.3.4 of TIS speciciation, that
 * TPM_GetCapability (short duration) commands should not be longer than 750ms
 * and that section 11.3.7 states that TPM_ContinueSelfTest (medium duration)
 * should not be longer than 1 second.
 */
#define DEFAULT_SHORT_DURATION  750000
#define DEFAULT_MEDIUM_DURATION 1000000
#define DEFAULT_LONG_DURATION   300000000
#define DEFAULT_TIMEOUT_A   750000
#define DEFAULT_TIMEOUT_B   2000000
#define DEFAULT_TIMEOUT_C   750000
#define DEFAULT_TIMEOUT_D   750000

/*
 * In order to test the 'millisecond bug', we test if DURATIONS and TIMEOUTS
 * are unreasonably low...such as 10 milliseconds (TPM isn't that fast).
 * and 400 milliseconds for long duration
 */
#define TEN_MILLISECONDS    10000   /* 10 milliseconds */
#define FOUR_HUNDRED_MILLISECONDS 400000    /* 4 hundred milliseconds */

/*
 * TPM input/output buffer offsets
 */

typedef enum {
    TPM_CAP_RESPSIZE_OFFSET = 10,
    TPM_CAP_RESP_OFFSET = 14,
} TPM_CAP_RET_OFFSET_T;

typedef enum {
    TPM_CAP_TIMEOUT_A_OFFSET = 14,
    TPM_CAP_TIMEOUT_B_OFFSET = 18,
    TPM_CAP_TIMEOUT_C_OFFSET = 22,
    TPM_CAP_TIMEOUT_D_OFFSET = 26,
} TPM_CAP_TIMEOUT_OFFSET_T;

typedef enum {
    TPM_CAP_DUR_SHORT_OFFSET = 14,
    TPM_CAP_DUR_MEDIUM_OFFSET = 18,
    TPM_CAP_DUR_LONG_OFFSET = 22,
} TPM_CAP_DURATION_OFFSET_T;

#define TPM_CAP_VERSION_INFO_OFFSET 14
#define TPM_CAP_VERSION_INFO_SIZE   15

/*
 * Internal TPM command functions
 */
static int itpm_command(tpm_state_t *tpm, uint8_t *buf, size_t bufsiz);
static int tpm_get_timeouts(tpm_state_t *tpm);
static int tpm_get_duration(tpm_state_t *tpm);
static int tpm_get_version(tpm_state_t *tpm);
static int tpm_continue_selftest(tpm_state_t *tpm);

/*
 * Internal TIS related functions
 */
static int tpm_wait_for_stat(tpm_state_t *, uint8_t, clock_t);
static clock_t tpm_get_ordinal_duration(tpm_state_t *, uint8_t);
static int tis_check_active_locality(tpm_state_t *, char);
static int tis_request_locality(tpm_state_t *, char);
static void tis_release_locality(tpm_state_t *, char, int);
static int tis_init(tpm_state_t *);
static uint8_t tis_get_status(tpm_state_t *);
static int tis_send_data(tpm_state_t *, uint8_t *, size_t);
static int tis_recv_data(tpm_state_t *, uint8_t *, size_t);

/* Auxilliary */
static int receive_data(tpm_state_t *, uint8_t *, size_t);
static inline int tpm_lock(tpm_state_t *);
static inline void tpm_unlock(tpm_state_t *);
static void tpm_cleanup(dev_info_t *, tpm_state_t *);

/*
 * Sun DDI/DDK entry points
 */

/* Declaration of autoconfig functions */
static int tpm_attach(dev_info_t *, ddi_attach_cmd_t);
static int tpm_detach(dev_info_t *, ddi_detach_cmd_t);
static int tpm_getinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
static int tpm_quiesce(dev_info_t *);
/* End of autoconfig functions */

/* Declaration of driver entry point functions */
static int tpm_open(dev_t *, int, int, cred_t *);
static int tpm_close(dev_t, int, int, cred_t *);
static int tpm_read(dev_t, struct uio *, cred_t *);
static int tpm_write(dev_t, struct uio *, cred_t *);
/* End of driver entry point functions */

/* cb_ops structure */
static struct cb_ops tpm_cb_ops = {
    tpm_open,
    tpm_close,
    nodev,      /* no strategy - nodev returns ENXIO */
    nodev,      /* no print */
    nodev,      /* no dump */
    tpm_read,
    tpm_write,
    nodev,      /* no ioctl */
    nodev,      /* no devmap */
    nodev,      /* no mmap */
    nodev,      /* no segmap */
    nochpoll,   /* returns ENXIO for non-pollable devices */
    ddi_prop_op,
    NULL,       /* streamtab struc */
    D_MP,       /* compatibility flags */
    CB_REV,     /* cb_ops revision number */
    nodev,      /* no aread */
    nodev       /* no awrite */
};

/* dev_ops structure */
static struct dev_ops tpm_dev_ops = {
    DEVO_REV,
    0,      /* reference count */
    tpm_getinfo,
    nulldev,    /* no identify - nulldev returns 0 */
    nulldev,
    tpm_attach,
    tpm_detach,
    nodev,      /* no reset - nodev returns ENXIO */
    &tpm_cb_ops,
    (struct bus_ops *)NULL,
    nodev,      /* no power */
    tpm_quiesce
};

/* modldrv structure */
static struct modldrv modldrv = {
    &mod_driverops,     /* Type: This is a driver */
    "TPM 1.2 driver",   /* Name of the module. */
    &tpm_dev_ops
};

/* modlinkage structure */
static struct modlinkage tpm_ml = {
    MODREV_1,
    &modldrv,
    NULL
};

static void *statep = NULL;

/*
 * TPM commands to get the TPM's properties, e.g.,timeout
 */
/*ARGSUSED*/
static int
tpm_quiesce(dev_info_t *dip)
{
    return (DDI_SUCCESS);
}

static uint32_t
load32(uchar_t *ptr, uint32_t offset)
{
    uint32_t val;
    bcopy(ptr + offset, &val, sizeof (uint32_t));

    return (ntohl(val));
}

/*
 * Get the actual timeouts supported by the TPM by issuing TPM_GetCapability
 * with the subcommand TPM_CAP_PROP_TIS_TIMEOUT
 * TPM_GetCapability (TPM Main Part 3 Rev. 94, pg.38)
 */
static int
tpm_get_timeouts(tpm_state_t *tpm)
{
    int ret;
    uint32_t timeout;   /* in milliseconds */
    uint32_t len;

    /* The buffer size (30) needs room for 4 timeout values (uint32_t) */
    uint8_t buf[30] = {
        0, 193,     /* TPM_TAG_RQU_COMMAND */
        0, 0, 0, 22,    /* paramsize in bytes */
        0, 0, 0, 101,   /* TPM_ORD_GetCapability */
        0, 0, 0, 5, /* TPM_CAP_Prop */
        0, 0, 0, 4, /* SUB_CAP size in bytes */
        0, 0, 1, 21 /* TPM_CAP_PROP_TIS_TIMEOUT(0x115) */
    };
    char *myname = "tpm_get_timeout";

    ASSERT(tpm != NULL);

    ret = itpm_command(tpm, buf, sizeof (buf));
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: itpm_command failed", myname);
        return (DDI_FAILURE);
    }

    /*
     * Get the length of the returned buffer
     * Make sure that there are 4 timeout values returned
     * length of the capability response is stored in data[10-13]
     * Also the TPM is in network byte order
     */
    len = load32(buf, TPM_CAP_RESPSIZE_OFFSET);
    if (len != 4 * sizeof (uint32_t)) {
        cmn_err(CE_WARN, "%s: capability response size should be %d"
            "instead it's %d",
            myname, (int)(4 * sizeof (uint32_t)), (int)len);
        return (DDI_FAILURE);
    }

    /* Get the four timeout's: a,b,c,d (they are 4 bytes long each) */
    timeout = load32(buf, TPM_CAP_TIMEOUT_A_OFFSET);
    if (timeout == 0) {
        timeout = DEFAULT_TIMEOUT_A;
    } else if (timeout < TEN_MILLISECONDS) {
        /* timeout is in millisecond range (should be microseconds) */
        timeout *= 1000;
    }
    tpm->timeout_a = drv_usectohz(timeout);

    timeout = load32(buf, TPM_CAP_TIMEOUT_B_OFFSET);
    if (timeout == 0) {
        timeout = DEFAULT_TIMEOUT_B;
    } else if (timeout < TEN_MILLISECONDS) {
        /* timeout is in millisecond range (should be microseconds) */
        timeout *= 1000;
    }
    tpm->timeout_b = drv_usectohz(timeout);

    timeout = load32(buf, TPM_CAP_TIMEOUT_C_OFFSET);
    if (timeout == 0) {
        timeout = DEFAULT_TIMEOUT_C;
    } else if (timeout < TEN_MILLISECONDS) {
        /* timeout is in millisecond range (should be microseconds) */
        timeout *= 1000;
    }
    tpm->timeout_c = drv_usectohz(timeout);

    timeout = load32(buf, TPM_CAP_TIMEOUT_D_OFFSET);
    if (timeout == 0) {
        timeout = DEFAULT_TIMEOUT_D;
    } else if (timeout < TEN_MILLISECONDS) {
        /* timeout is in millisecond range (should be microseconds) */
        timeout *= 1000;
    }
    tpm->timeout_d = drv_usectohz(timeout);

    return (DDI_SUCCESS);
}

/*
 * Get the actual timeouts supported by the TPM by issuing TPM_GetCapability
 * with the subcommand TPM_CAP_PROP_TIS_DURATION
 * TPM_GetCapability (TPM Main Part 3 Rev. 94, pg.38)
 */
static int
tpm_get_duration(tpm_state_t *tpm) {
    int ret;
    uint32_t duration;
    uint32_t len;
    uint8_t buf[30] = {
        0, 193,     /* TPM_TAG_RQU_COMMAND */
        0, 0, 0, 22,    /* paramsize in bytes */
        0, 0, 0, 101,   /* TPM_ORD_GetCapability */
        0, 0, 0, 5, /* TPM_CAP_Prop */
        0, 0, 0, 4, /* SUB_CAP size in bytes */
        0, 0, 1, 32 /* TPM_CAP_PROP_TIS_DURATION(0x120) */
    };
    char *myname = "tpm_get_duration";

    ASSERT(tpm != NULL);

    ret = itpm_command(tpm, buf, sizeof (buf));
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: itpm_command failed with ret code: 0x%x",
            myname, ret);
        return (DDI_FAILURE);
    }

    /*
     * Get the length of the returned buffer
     * Make sure that there are 3 duration values (S,M,L: in that order)
     * length of the capability response is stored in data[10-13]
     * Also the TPM is in network byte order
     */
    len = load32(buf, TPM_CAP_RESPSIZE_OFFSET);
    if (len != 3 * sizeof (uint32_t)) {
        cmn_err(CE_WARN, "%s: capability response should be %d, "
            "instead, it's %d",
            myname, (int)(3 * sizeof (uint32_t)), (int)len);
        return (DDI_FAILURE);
    }

    duration = load32(buf, TPM_CAP_DUR_SHORT_OFFSET);
    if (duration == 0) {
        duration = DEFAULT_SHORT_DURATION;
    } else if (duration < TEN_MILLISECONDS) {
        duration *= 1000;
    }
    tpm->duration[TPM_SHORT] = drv_usectohz(duration);

    duration = load32(buf, TPM_CAP_DUR_MEDIUM_OFFSET);
    if (duration == 0) {
        duration = DEFAULT_MEDIUM_DURATION;
    } else if (duration < TEN_MILLISECONDS) {
        duration *= 1000;
    }
    tpm->duration[TPM_MEDIUM] = drv_usectohz(duration);

    duration = load32(buf, TPM_CAP_DUR_LONG_OFFSET);
    if (duration == 0) {
        duration = DEFAULT_LONG_DURATION;
    } else if (duration < FOUR_HUNDRED_MILLISECONDS) {
        duration *= 1000;
    }
    tpm->duration[TPM_LONG] = drv_usectohz(duration);

    /* Just make the undefined duration be the same as the LONG */
    tpm->duration[TPM_UNDEFINED] = tpm->duration[TPM_LONG];

    return (DDI_SUCCESS);
}

/*
 * Get the actual timeouts supported by the TPM by issuing TPM_GetCapability
 * with the subcommand TPM_CAP_PROP_TIS_DURATION
 * TPM_GetCapability (TPM Main Part 3 Rev. 94, pg.38)
 */
static int
tpm_get_version(tpm_state_t *tpm) {
    int ret;
    uint32_t len;
    char vendorId[5];
    /* If this buf is too small, the "vendor specific" data won't fit */
    uint8_t buf[64] = {
        0, 193,     /* TPM_TAG_RQU_COMMAND */
        0, 0, 0, 18,    /* paramsize in bytes */
        0, 0, 0, 101,   /* TPM_ORD_GetCapability */
        0, 0, 0, 0x1A,  /* TPM_CAP_VERSION_VAL */
        0, 0, 0, 0, /* SUB_CAP size in bytes */
    };
    char *myname = "tpm_get_version";

    ASSERT(tpm != NULL);

    ret = itpm_command(tpm, buf, sizeof (buf));
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: itpm_command failed with ret code: 0x%x",
            myname, ret);
        return (DDI_FAILURE);
    }

    /*
     * Get the length of the returned buffer.
     */
    len = load32(buf, TPM_CAP_RESPSIZE_OFFSET);
    if (len < TPM_CAP_VERSION_INFO_SIZE) {
        cmn_err(CE_WARN, "%s: capability response should be greater"
            " than %d, instead, it's %d",
            myname,
            TPM_CAP_VERSION_INFO_SIZE,
            len);
        return (DDI_FAILURE);
    }

    bcopy(buf + TPM_CAP_VERSION_INFO_OFFSET, &tpm->vers_info,
        TPM_CAP_VERSION_INFO_SIZE);

    bcopy(tpm->vers_info.tpmVendorID, vendorId,
        sizeof (tpm->vers_info.tpmVendorID));
    vendorId[4] = '\0';

    cmn_err(CE_NOTE, "!TPM found: Ver %d.%d, Rev %d.%d, "
        "SpecLevel %d, errataRev %d, VendorId '%s'",
        tpm->vers_info.version.major,   /* Version */
        tpm->vers_info.version.minor,
        tpm->vers_info.version.revMajor,    /* Revision */
        tpm->vers_info.version.revMinor,
        (int)ntohs(tpm->vers_info.specLevel),
        tpm->vers_info.errataRev,
        vendorId);

    /*
     * This driver only supports TPM Version 1.2
     */
    if (tpm->vers_info.version.major != 1 &&
        tpm->vers_info.version.minor != 2) {
        cmn_err(CE_WARN, "%s: Unsupported TPM version (%d.%d)",
            myname,
            tpm->vers_info.version.major,       /* Version */
            tpm->vers_info.version.minor);
        return (DDI_FAILURE);
    }

    return (DDI_SUCCESS);
}

/*
 * To prevent the TPM from complaining that certain functions are not tested
 * we run this command when the driver attaches.
 * For details see Section 4.2 of TPM Main Part 3 Command Specification
 */
static int
tpm_continue_selftest(tpm_state_t *tpm) {
    int ret;
    uint8_t buf[10] = {
        0, 193,     /* TPM_TAG_RQU COMMAND */
        0, 0, 0, 10,    /* paramsize in bytes */
        0, 0, 0, 83 /* TPM_ORD_ContinueSelfTest */
    };
    char *myname = "tpm_continue_selftest";

    /* Need a longer timeout */
    ret = itpm_command(tpm, buf, sizeof (buf));
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: itpm_command failed", myname);
        return (DDI_FAILURE);
    }

    return (DDI_SUCCESS);
}
/*
 * Auxilary Functions
 */

/*
 * Find out how long we should wait for the TPM command to complete a command
 */
static clock_t
tpm_get_ordinal_duration(tpm_state_t *tpm, uint8_t ordinal)
{
    uint8_t index;
    char *myname = "tpm_get_ordinal_duration";

    ASSERT(tpm != NULL);

    /* Default and failure case for IFX */
    /* Is it a TSC_ORDINAL? */
    if (ordinal & TSC_ORDINAL_MASK) {
        if (ordinal > TSC_ORDINAL_MAX) {
            cmn_err(CE_WARN,
                "%s: tsc ordinal: %d exceeds MAX: %d",
                myname, ordinal, TSC_ORDINAL_MAX);
            return (0);
        }
        index = tsc_ords_duration[ordinal];
    } else {
        if (ordinal > TPM_ORDINAL_MAX) {
            cmn_err(CE_WARN,
                "%s: ordinal %d exceeds MAX: %d",
                myname, ordinal, TPM_ORDINAL_MAX);
            return (0);
        }
        index = tpm_ords_duration[ordinal];
    }

    if (index > TPM_DURATION_MAX_IDX) {
        cmn_err(CE_WARN, "%s: FATAL:index '%d' is out of bound",
            myname, index);
        return (0);
    }
    return (tpm->duration[index]);
}

/*
 * Internal TPM Transmit Function:
 * Calls implementation specific sendto and receive
 * The code assumes that the buffer is in network byte order
 */
static int
itpm_command(tpm_state_t *tpm, uint8_t *buf, size_t bufsiz)
{
    int ret;
    uint32_t count;
    char *myname = "itpm_command";

    ASSERT(tpm != NULL && buf != NULL);

    /* The byte order is network byte order so convert it */
    count = load32(buf, TPM_PARAMSIZE_OFFSET);

    if (count == 0) {
        cmn_err(CE_WARN, "%s: count=0, no data? %d", myname,
            (int)bufsiz);
        return (DDI_FAILURE);
    }
    if (count > bufsiz) {
        cmn_err(CE_WARN, "%s: invalid count value:count:%d > bufsiz %d",
            myname, (int)count, (int)bufsiz);
        return (DDI_FAILURE);
    }

    /* Send the command */
    ret = tis_send_data(tpm, buf, count);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: tis_send_data failed with error %x",
            myname, ret);
        return (DDI_FAILURE);
    }

    /*
     * Now receive the data from the tpm
     * Should at least receive "the common" 10 bytes (TPM_HEADER_SIZE)
     */
    ret = tis_recv_data(tpm, buf, bufsiz);
    if (ret < TPM_HEADER_SIZE) {
        cmn_err(CE_WARN, "%s: tis_recv_data failed", myname);
        return (DDI_FAILURE);
    }

    /* Check the return code */
    ret = load32(buf, TPM_RETURN_OFFSET);
    if (ret != TPM_SUCCESS) {
        cmn_err(CE_WARN, "%s: command failed with ret code: %x",
            myname, ret);
        return (DDI_FAILURE);
    }

    return (DDI_SUCCESS);
}

/*
 * Whenever the driver wants to write to the DATA_IO register, it must need
 * to figure out the burstcount.  This is the amount of bytes it can write
 * before having to wait for long LPC bus cycle
 *
 * Returns: 0 if error, burst count if sucess
 */
static uint16_t
tpm_get_burstcount(tpm_state_t *tpm) {
    clock_t stop;
    uint16_t burstcnt;

    ASSERT(tpm != NULL);

    /*
     * Spec says timeout should be TIMEOUT_D
     * burst count is TPM_STS bits 8..23
     */
    stop = ddi_get_lbolt() + tpm->timeout_d;
    do {
        /*
         * burstcnt is stored as a little endian value
         * 'ntohs' doesn't work since the value is not word-aligned
         */
        burstcnt = ddi_get8(tpm->handle,
            (uint8_t *)(tpm->addr+
            TPM_STS_(tpm->locality)+1));
        burstcnt += ddi_get8(tpm->handle,
            (uint8_t *)(tpm->addr+
            TPM_STS_(tpm->locality)+2)) << 8;

        if (burstcnt)
            return (burstcnt);

        delay(tpm->timeout_poll);
    } while (ddi_get_lbolt() < stop);

    return (0);
}

/*
 * Writing 1 to TPM_STS_CMD_READY bit in TPM_STS will do the following:
 * 1. The TPM will clears IO buffers if any
 * 2. The TPM will enters either Idle or Ready state within TIMEOUT_B
 * (checked in the calling function)
 */
static void
tpm_set_ready(tpm_state_t *tpm) {
    ASSERT(tpm != NULL);

    ddi_put8(tpm->handle,
        (uint8_t *)(tpm->addr+TPM_STS_(tpm->locality)),
        TPM_STS_CMD_READY);
}

static int
receive_data(tpm_state_t *tpm, uint8_t *buf, size_t bufsiz) {
    int size = 0;
    int retried = 0;
    uint8_t stsbits;

    /* A number of consecutive bytes that can be written to TPM */
    uint16_t burstcnt;

    ASSERT(tpm != NULL && buf != NULL);
retry:
    while (size < bufsiz &&
        (tpm_wait_for_stat(tpm,
            (TPM_STS_DATA_AVAIL|TPM_STS_VALID),
            (ddi_get_lbolt() + tpm->timeout_c)) == DDI_SUCCESS)) {
        /*
         * Burstcount should be available within TIMEOUT_D
         * after STS is set to valid
         * burstcount is dynamic, so have to get it each time
         */
        burstcnt = tpm_get_burstcount(tpm);
        for (; burstcnt > 0 && size < bufsiz; burstcnt--) {
            buf[size++] = ddi_get8(tpm->handle,
                (uint8_t *)(tpm->addr +
                TPM_DATA_FIFO_(tpm->locality)));
        }
    }
    stsbits = tis_get_status(tpm);
    /* check to see if we need to retry (just once) */
    if (size < bufsiz && !(stsbits & TPM_STS_DATA_AVAIL) && retried == 0) {
        /* issue responseRetry (TIS 1.2 pg 54) */
        ddi_put8(tpm->handle,
            (uint8_t *)(tpm->addr+TPM_STS_(tpm->locality)),
            TPM_STS_RESPONSE_RETRY);
        /* update the retry counter so we only retry once */
        retried++;
        /* reset the size to 0 and reread the entire response */
        size = 0;
        goto retry;
    }
    return (size);
}

/* Receive the data from the TPM */
static int
tis_recv_data(tpm_state_t *tpm, uint8_t *buf, size_t bufsiz) {
    int ret;
    int size = 0;
    uint32_t expected, status;
    uint32_t cmdresult;
    char *myname = "tis_recv_data";

    ASSERT(tpm != NULL && buf != NULL);

    if (bufsiz < TPM_HEADER_SIZE) {
        /* There should be at least tag,paramsize,return code */
        cmn_err(CE_WARN, "%s: received data should contain at least "
            "the header which is %d bytes long",
            myname, TPM_HEADER_SIZE);
        goto OUT;
    }

    /* Read tag(2 bytes), paramsize(4), and result(4) */
    size = receive_data(tpm, buf, TPM_HEADER_SIZE);
    if (size < TPM_HEADER_SIZE) {
        cmn_err(CE_WARN, "%s: getting the TPM_HEADER failed: size=%d",
            myname, size);
        goto OUT;
    }

    cmdresult = load32(buf, TPM_RETURN_OFFSET);

    /* Get 'paramsize'(4 bytes)--it includes tag and paramsize */
    expected = load32(buf, TPM_PARAMSIZE_OFFSET);
    if (expected > bufsiz) {
        cmn_err(CE_WARN, "%s: paramSize is bigger "
            "than the requested size: paramSize=%d bufsiz=%d result=%d",
            myname, (int)expected, (int)bufsiz, cmdresult);
        goto OUT;
    }

    /* Read in the rest of the data from the TPM */
    size += receive_data(tpm, (uint8_t *)&buf[TPM_HEADER_SIZE],
        expected - TPM_HEADER_SIZE);
    if (size < expected) {
        cmn_err(CE_WARN, "%s: received data length=%d "
            "is less than expected = %d", myname, size, expected);
        goto OUT;
    }

    /* The TPM MUST set the state to stsValid within TIMEOUT_C */
    ret = tpm_wait_for_stat(tpm, TPM_STS_VALID,
        ddi_get_lbolt() + tpm->timeout_c);

    status = tis_get_status(tpm);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: TPM didn't set stsValid after its I/O: "
            "status = 0x%08X", myname, status);
        goto OUT;
    }

    /* There is still more data? */
    if (status & TPM_STS_DATA_AVAIL) {
        cmn_err(CE_WARN, "%s: Status TPM_STS_DATA_AVAIL set:0x%08X",
            myname, status);
        goto OUT;
    }

    /*
     * Release the control of the TPM after we are done with it
     * it...so others can also get a chance to send data
     */
    tis_release_locality(tpm, tpm->locality, 0);

OUT:
    tpm_set_ready(tpm);
    tis_release_locality(tpm, tpm->locality, 0);
    return (size);
}

/*
 * Send the data (TPM commands) to the Data IO register
 */
static int
tis_send_data(tpm_state_t *tpm, uint8_t *buf, size_t bufsiz) {
    int ret;
    uint8_t status;
    uint16_t burstcnt;
    uint32_t ordinal;
    size_t count = 0;
    char *myname = "tis_send_data";

    ASSERT(tpm != NULL && buf != NULL);

    if (bufsiz == 0) {
        cmn_err(CE_WARN, "%s: passed in argument bufsize is zero",
            myname);
        return (DDI_FAILURE);
    }

    /* Be in the right locality (aren't we always in locality 0?) */
    if (tis_request_locality(tpm, 0) != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: tis_request_locality didn't enter "
            "locality 0", myname);
        return (DDI_FAILURE);
    }

    /* Put the TPM in ready state */
    status = tis_get_status(tpm);

    if (!(status & TPM_STS_CMD_READY)) {
        tpm_set_ready(tpm);
        ret = tpm_wait_for_stat(tpm,
            TPM_STS_CMD_READY,
            (ddi_get_lbolt() + tpm->timeout_b));
        if (ret != DDI_SUCCESS) {
            cmn_err(CE_WARN, "%s: could not put the TPM "
                "in the command ready state:"
                "tpm_wait_for_stat returned error",
                myname);
            goto FAIL;
        }
    }

    /*
     * Now we are ready to send command
     * TPM's burstcount dictates how many bytes we can write at a time
     * Burstcount is dynamic if INTF_CAPABILITY for static burstcount is
     * not set.
     */
    while (count < bufsiz - 1) {
        burstcnt = tpm_get_burstcount(tpm);
        if (burstcnt == 0) {
            cmn_err(CE_WARN, "%s: tpm_get_burstcnt returned error",
                myname);
            ret = DDI_FAILURE;
            goto FAIL;
        }

        for (; burstcnt > 0 && count < bufsiz - 1; burstcnt--) {
            ddi_put8(tpm->handle, (uint8_t *)(tpm->addr+
                TPM_DATA_FIFO_(tpm->locality)), buf[count]);
            count++;
        }
        /* Wait for TPM to indicate that it is ready for more data */
        ret = tpm_wait_for_stat(tpm,
            (TPM_STS_VALID | TPM_STS_DATA_EXPECT),
            (ddi_get_lbolt() + tpm->timeout_c));
        if (ret != DDI_SUCCESS) {
            cmn_err(CE_WARN, "%s: TPM didn't enter stsvalid "
                "state after sending the data:", myname);
            goto FAIL;
        }
    }
    /* We can't exit the loop above unless we wrote bufsiz-1 bytes */

    /* Write last byte */
    ddi_put8(tpm->handle, (uint8_t *)(tpm->addr +
        TPM_DATA_FIFO_(tpm->locality)), buf[count]);
    count++;

    /* Wait for the TPM to enter Valid State */
    ret = tpm_wait_for_stat(tpm,
        TPM_STS_VALID, (ddi_get_lbolt() + tpm->timeout_c));
    if (ret == DDI_FAILURE) {
        cmn_err(CE_WARN, "%s: tpm didn't enter Valid state", myname);
        goto FAIL;
    }

    status = tis_get_status(tpm);
    /* The TPM should NOT be expecing more data at this point */
    if ((status & TPM_STS_DATA_EXPECT) != 0) {
        cmn_err(CE_WARN, "%s: DATA_EXPECT is set (shouldn't be) after "
            "writing the last byte: status=0x%08X", myname, status);
        ret = DDI_FAILURE;
        goto FAIL;
    }

    /*
     * Final step: Writing TPM_STS_GO to TPM_STS
     * register will actually send the command.
     */
    ddi_put8(tpm->handle, (uint8_t *)(tpm->addr+TPM_STS_(tpm->locality)),
        TPM_STS_GO);

    /* Ordinal/Command_code is located in buf[6..9] */
    ordinal = load32(buf, TPM_COMMAND_CODE_OFFSET);

    ret = tpm_wait_for_stat(tpm, TPM_STS_DATA_AVAIL | TPM_STS_VALID,
        ddi_get_lbolt() + tpm_get_ordinal_duration(tpm, ordinal));
    if (ret == DDI_FAILURE) {
        status = tis_get_status(tpm);
        if (!(status & TPM_STS_DATA_AVAIL) ||
            !(status & TPM_STS_VALID)) {
            cmn_err(CE_WARN, "%s: TPM not ready or valid "
                "(ordinal = %d timeout = %ld)",
                myname, ordinal,
                tpm_get_ordinal_duration(tpm, ordinal));
        } else {
            cmn_err(CE_WARN, "%s: tpm_wait_for_stat "
                "(DATA_AVAIL | VALID) failed: STS = 0x%0X",
                myname, status);
        }
        goto FAIL;
    }
    return (DDI_SUCCESS);

FAIL:
    tpm_set_ready(tpm);
    tis_release_locality(tpm, tpm->locality, 0);
    return (ret);
}

/*
 * Clear XrequestUse and Xactivelocality, where X is the current locality
 */
static void
tis_release_locality(tpm_state_t *tpm, char locality, int force) {
    ASSERT(tpm != NULL && locality >= 0 && locality < 5);

    if (force ||
        (ddi_get8(tpm->handle,
        (uchar_t *)(tpm->addr+TPM_ACCESS_(locality)))
        & (TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID))
        == (TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID)) {
        /*
         * Writing 1 to active locality bit in TPM_ACCESS
         * register reliquishes the control of the locality
         */
        ddi_put8(tpm->handle,
            (uint8_t *)(tpm->addr+TPM_ACCESS_(locality)),
            TPM_ACCESS_ACTIVE_LOCALITY);
    }
}

/*
 * Checks whether the given locality is active
 * Use TPM_ACCESS register and the masks TPM_ACCESS_VALID,TPM_ACTIVE_LOCALITY
 */
static int
tis_check_active_locality(tpm_state_t *tpm, char locality) {
    uint8_t access_bits;

    ASSERT(tpm != NULL && locality >= 0 && locality < 5);

    access_bits = ddi_get8(tpm->handle,
        (uint8_t *)(tpm->addr+TPM_ACCESS_(locality)));
    access_bits &= (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID);

    if (access_bits == (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID))
        return (DDI_SUCCESS);
    else
        return (DDI_FAILURE);
}

/* Request the TPM to be in the given locality */
static int
tis_request_locality(tpm_state_t *tpm, char locality) {
    clock_t timeout;
    int ret;
    char *myname = "tis_request_locality";

    ASSERT(tpm != NULL && locality >= 0 && locality < 5);

    ret = tis_check_active_locality(tpm, locality);

    if (ret == DDI_SUCCESS) {
        /* Locality is already active */
        tpm->locality = locality;
        return (DDI_SUCCESS);
    }

    ddi_put8(tpm->handle, tpm->addr+TPM_ACCESS_(locality),
        TPM_ACCESS_REQUEST_USE);
    timeout = ddi_get_lbolt() + tpm->timeout_a;

    /* Using polling */
    while (tis_check_active_locality(tpm, locality)
        != DDI_SUCCESS) {
        if (ddi_get_lbolt() >= timeout) {
            cmn_err(CE_WARN, "%s (interrupt-disabled) "
                "tis_request_locality timed out",
                myname);
            return (DDI_FAILURE);
        }
        delay(tpm->timeout_poll);
    }

    tpm->locality = locality;
    return (DDI_SUCCESS);
}

/* Read the status register */
static uint8_t
tis_get_status(tpm_state_t *tpm) {
    return (ddi_get8(tpm->handle,
        (uint8_t *)(tpm->addr+TPM_STS_(tpm->locality))));
}

static int
tpm_wait_for_stat(tpm_state_t *tpm, uint8_t mask, clock_t absolute_timeout) {
    char *myname = "tpm_wait_for_stat";

    /* Using polling */
    while ((tis_get_status(tpm) & mask) != mask) {
        if (ddi_get_lbolt() >= absolute_timeout) {
            /* Timeout reached */
            cmn_err(CE_WARN, "%s: using "
                "polling:reached timeout",
                myname);
            return (DDI_FAILURE);
        }
        delay(tpm->timeout_poll);
    }
    return (DDI_SUCCESS);
}

/*
 * Initialize TPM device
 * 1. Find out supported interrupt capabilities
 * 2. Set up interrupt handler if supported (some BIOSes don't support
 * interrupts for TPMS, in which case we set up polling)
 * 3. Determine timeouts and commands duration
 */
static int
tis_init(tpm_state_t *tpm) {
    uint32_t intf_caps;
    int ret;
    char *myname = "tis_init";
    uintptr_t aptr = (uintptr_t)tpm->addr;

    /*
     * Temporarily set up timeouts before we get the real timeouts
     * by issuing TPM_CAP commands (but to issue TPM_CAP commands,
     * you need TIMEOUTs defined...chicken and egg problem here.
     * TPM timeouts: Convert the milliseconds to clock cycles
     */
    tpm->timeout_a = drv_usectohz(TIS_TIMEOUT_A);
    tpm->timeout_b = drv_usectohz(TIS_TIMEOUT_B);
    tpm->timeout_c = drv_usectohz(TIS_TIMEOUT_C);
    tpm->timeout_d = drv_usectohz(TIS_TIMEOUT_D);
    /*
     * Do the same with the duration (real duration will be filled out
     * when we call TPM_GetCapability to get the duration values from
     * the TPM itself).
     */
    tpm->duration[TPM_SHORT] = drv_usectohz(TPM_DEFAULT_DURATION);
    tpm->duration[TPM_MEDIUM] = drv_usectohz(TPM_DEFAULT_DURATION);
    tpm->duration[TPM_LONG] = drv_usectohz(TPM_DEFAULT_DURATION);
    tpm->duration[TPM_UNDEFINED] = drv_usectohz(TPM_DEFAULT_DURATION);

    /* Find out supported capabilities */
    intf_caps = ddi_get32(tpm->handle,
        (uint32_t *)(aptr + TPM_INTF_CAP_(0)));

    /* Upper 3 bytes should always return 0 */
    if (intf_caps & 0x7FFFFF00) {
#ifdef DEBUG
        cmn_err(CE_WARN, "%s: bad intf_caps value 0x%0X",
            myname, intf_caps);
#endif
        return (DDI_FAILURE);
    }

    /* These two interrupts are mandatory */
    if (!(intf_caps & TPM_INTF_INT_LOCALITY_CHANGE_INT)) {
        cmn_err(CE_WARN, "%s: Mandatory capability Locality Change Int "
            "not supported", myname);
        return (DDI_FAILURE);
    }
    if (!(intf_caps & TPM_INTF_INT_DATA_AVAIL_INT)) {
        cmn_err(CE_WARN, "%s: Mandatory capability Data Available Int "
            "not supported", myname);
        return (DDI_FAILURE);
    }

    /*
     * Before we start writing anything to TPM's registers,
     * make sure we are in locality 0
     */
    ret = tis_request_locality(tpm, 0);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: Unable to request locality 0", myname);
        return (DDI_FAILURE);
    } /* Now we can refer to the locality as tpm->locality */

    tpm->timeout_poll = drv_usectohz(TPM_POLLING_TIMEOUT);
    tpm->intr_enabled = 0;

    /* Get the real timeouts from the TPM */
    ret = tpm_get_timeouts(tpm);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: tpm_get_timeouts error", myname);
        return (DDI_FAILURE);
    }

    ret = tpm_get_duration(tpm);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: tpm_get_duration error", myname);
        return (DDI_FAILURE);
    }

    /* This gets the TPM version information */
    ret = tpm_get_version(tpm);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: tpm_get_version error", myname);
        return (DDI_FAILURE);
    }

    /*
     * Unless the TPM completes the test of its commands,
     * it can return an error when the untested commands are called
     */
    ret = tpm_continue_selftest(tpm);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: tpm_continue_selftest error", myname);
        return (DDI_FAILURE);
    }
    return (DDI_SUCCESS);
}

/*
 * Module Entry points
 */
int
_init(void)
{
    int ret;

    ret = ddi_soft_state_init(&statep, sizeof (tpm_state_t), 1);
    if (ret)
        return (ret);

    ret = mod_install(&tpm_ml);
    if (ret != 0) {
        cmn_err(CE_WARN, "_init: mod_install returned non-zero");
        ddi_soft_state_fini(&statep);
        return (ret);
    }

    return (ret);
}

int
_info(struct modinfo *modinfop)
{
    int ret;
    ret = mod_info(&tpm_ml, modinfop);
    if (ret == 0)
        cmn_err(CE_WARN, "mod_info failed: %d", ret);

    return (ret);
}

int
_fini()
{
    int ret;
    ret = mod_remove(&tpm_ml);
    if (ret != 0) {
        return (ret);
    }
    ddi_soft_state_fini(&statep);

    return (ret);
}
/* End of driver configuration functions */

static int
tpm_resume(tpm_state_t *tpm)
{
    mutex_enter(&tpm->pm_mutex);
    if (!tpm->suspended) {
        mutex_exit(&tpm->pm_mutex);
        return (DDI_FAILURE);
    }
    tpm->suspended = 0;
    cv_broadcast(&tpm->suspend_cv);
    mutex_exit(&tpm->pm_mutex);

    return (DDI_SUCCESS);
}

/*
 * Sun DDI/DDK entry points
 */
static int
tpm_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
    int ret, idx;
    int instance;
    int nregs;
    char *myname = "tpm_attach";
    tpm_state_t *tpm = NULL;

    ASSERT(dip != NULL);

    instance = ddi_get_instance(dip);

    /* Nothing out of ordinary here */
    switch (cmd) {
    case DDI_ATTACH:
        ret = ddi_soft_state_zalloc(statep, instance);
        if (ret != DDI_SUCCESS) {
            cmn_err(CE_WARN, "%s could not allocate tpm_state_t",
                myname);
            goto FAIL;
        }
        tpm = ddi_get_soft_state(statep, instance);
        tpm->dip = dip;
        break;
    case DDI_RESUME:
        tpm = ddi_get_soft_state(statep, instance);
        if (tpm == NULL) {
            cmn_err(CE_WARN, "%s: tpm_state_t is NULL",
                myname);
            goto FAIL;
        }
        return (tpm_resume(tpm));
    default:
        cmn_err(CE_WARN, "%s: cmd %d is not implemented", myname, cmd);
        ret = DDI_FAILURE;
        goto FAIL;
    }

    /* Zeroize the flag, which is used to keep track of what is allocated */
    tpm->flags = 0;

    tpm->accattr.devacc_attr_version = DDI_DEVICE_ATTR_V0;
    tpm->accattr.devacc_attr_endian_flags = DDI_NEVERSWAP_ACC;
    tpm->accattr.devacc_attr_dataorder = DDI_STRICTORDER_ACC;

    idx = 0;
    ret = ddi_dev_nregs(tpm->dip, &nregs);
    if (ret != DDI_SUCCESS)
        goto FAIL;

    /*
     * TPM vendors put the TPM registers in different
     * slots in their register lists.  They are not always
     * the 1st set of registers, for instance.
     * Loop until we find the set that matches the expected
     * register size (0x5000).
     */
    for (idx = 0; idx < nregs; idx++) {
        off_t regsize;

        if ((ret = ddi_dev_regsize(tpm->dip, idx, &regsize)) !=
            DDI_SUCCESS)
            goto FAIL;
        /* The TIS spec says the TPM registers must be 0x5000 bytes */
        if (regsize == 0x5000)
            break;
    }
    if (idx == nregs)
        return (DDI_FAILURE);

    ret = ddi_regs_map_setup(tpm->dip, idx, (caddr_t *)&tpm->addr,
        (offset_t)0, (offset_t)0x5000,
        &tpm->accattr, &tpm->handle);

    if (ret != DDI_SUCCESS) {
        goto FAIL;
    }
    tpm->flags |= TPM_DIDREGSMAP;

    /* Enable TPM device according to the TIS specification */
    ret = tis_init(tpm);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: tis_init() failed ret: %d",
            myname, ret);

        /* We need to clean up the ddi_regs_map_setup call */
        ddi_regs_map_free(&tpm->handle);
        tpm->handle = NULL;
        tpm->flags &= ~TPM_DIDREGSMAP;
        goto FAIL;
    }

    /* Initialize the inter-process lock */
    mutex_init(&tpm->dev_lock, NULL, MUTEX_DRIVER, NULL);
    mutex_init(&tpm->pm_mutex, NULL, MUTEX_DRIVER, NULL);
    cv_init(&tpm->suspend_cv, NULL, CV_DRIVER, NULL);

    /* Set the suspend/resume property */
    (void) ddi_prop_update_string(DDI_DEV_T_NONE, dip,
        "pm-hardware-state", "needs-suspend-resume");

    mutex_enter(&tpm->pm_mutex);
    tpm->suspended = 0;
    mutex_exit(&tpm->pm_mutex);

    tpm->flags |= TPM_DID_MUTEX;

    /* Initialize the buffer and the lock associated with it */
    tpm->bufsize = TPM_IO_BUF_SIZE;
    tpm->iobuf = kmem_zalloc((sizeof (uint8_t))*(tpm->bufsize), KM_SLEEP);
    if (tpm->iobuf == NULL) {
        cmn_err(CE_WARN, "%s: failed to allocate iobuf", myname);
        goto FAIL;
    }
    tpm->flags |= TPM_DID_IO_ALLOC;

    mutex_init(&tpm->iobuf_lock, NULL, MUTEX_DRIVER, NULL);
    tpm->flags |= TPM_DID_IO_MUTEX;

    cv_init(&tpm->iobuf_cv, NULL, CV_DRIVER, NULL);
    tpm->flags |= TPM_DID_IO_CV;

    /* Create minor node */
    ret = ddi_create_minor_node(dip, "tpm", S_IFCHR, ddi_get_instance(dip),
        DDI_PSEUDO, 0);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: ddi_create_minor_node failed", myname);
        goto FAIL;
    }
    tpm->flags |= TPM_DIDMINOR;

    return (DDI_SUCCESS);
FAIL:
    if (tpm != NULL) {
        tpm_cleanup(dip, tpm);
        ddi_soft_state_free(statep, instance);
        tpm = NULL;
    }

    return (DDI_FAILURE);
}

/*
 * Called by tpm_detach and tpm_attach (only on failure)
 * Free up the resources that are allocated
 */
static void
tpm_cleanup(dev_info_t *dip, tpm_state_t *tpm)
{
    if (tpm == NULL)
        return;

    if (tpm->flags & TPM_DID_MUTEX) {
        mutex_destroy(&tpm->dev_lock);
        tpm->flags &= ~(TPM_DID_MUTEX);
    }
    if (tpm->flags & TPM_DID_IO_ALLOC) {
        ASSERT(tpm->iobuf != NULL);
        kmem_free(tpm->iobuf, (sizeof (uint8_t))*(tpm->bufsize));
        tpm->flags &= ~(TPM_DID_IO_ALLOC);
    }
    if (tpm->flags & TPM_DID_IO_MUTEX) {
        mutex_destroy(&tpm->iobuf_lock);
        tpm->flags &= ~(TPM_DID_IO_MUTEX);
    }
    if (tpm->flags & TPM_DID_IO_CV) {
        cv_destroy(&tpm->iobuf_cv);
        tpm->flags &= ~(TPM_DID_IO_CV);
    }
    if (tpm->flags & TPM_DIDREGSMAP) {
        /* Free the mapped addresses */
        if (tpm->handle != NULL)
            ddi_regs_map_free(&tpm->handle);
        tpm->flags &= ~(TPM_DIDREGSMAP);
    }
    if (tpm->flags & TPM_DIDMINOR) {
        /* Remove minor node */
        ddi_remove_minor_node(dip, NULL);
        tpm->flags &= ~(TPM_DIDMINOR);
    }
}

static int
tpm_suspend(tpm_state_t *tpm)
{
    if (tpm == NULL)
        return (DDI_FAILURE);
    mutex_enter(&tpm->pm_mutex);
    if (tpm->suspended) {
        mutex_exit(&tpm->pm_mutex);
        return (DDI_SUCCESS);
    }
    tpm->suspended = 1;
    mutex_exit(&tpm->pm_mutex);

    return (DDI_SUCCESS);
}

static int
tpm_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
    char *myname = "tpm_detach";
    int instance;
    tpm_state_t *tpm;

    ASSERT(dip != NULL);

    instance = ddi_get_instance(dip);
    if ((tpm = ddi_get_soft_state(statep, instance)) == NULL) {
        cmn_err(CE_WARN, "%s: stored pointer to tpm state is NULL",
            myname);
        return (ENXIO);
    }

    switch (cmd) {
    case DDI_DETACH:
        /* Body is after the switch stmt */
        break;
    case DDI_SUSPEND:
        return (tpm_suspend(tpm));
    default:
        cmn_err(CE_WARN, "%s: case %d not implemented", myname, cmd);
        return (DDI_FAILURE);
    }

    /* Since we are freeing tpm structure, we need to gain the lock */

    tpm_cleanup(dip, tpm);

    mutex_destroy(&tpm->pm_mutex);
    cv_destroy(&tpm->suspend_cv);

    /* Free the soft state */
    ddi_soft_state_free(statep, instance);
    tpm = NULL;

    return (DDI_SUCCESS);
}

/*ARGSUSED*/
static int
tpm_getinfo(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg, void **resultp)
{
    char *myname = "tpm_getinfo";
    int instance;
    tpm_state_t *tpm;

    instance = ddi_get_instance(dip);
    if ((tpm = ddi_get_soft_state(statep, instance)) == NULL) {
        cmn_err(CE_WARN, "%s: stored pointer to tpm state is NULL",
            myname);
        return (DDI_FAILURE);
    }

    switch (cmd) {
    case DDI_INFO_DEVT2DEVINFO:
        *resultp = tpm->dip;
        break;
    case DDI_INFO_DEVT2INSTANCE:
        *resultp = 0;
        break;
    default:
        cmn_err(CE_WARN, "%s: cmd %d is not implemented", myname, cmd);
        return (DDI_FAILURE);
    }
    return (DDI_SUCCESS);
}

/*
 * Driver entry points
 */

/*ARGSUSED*/
static int
tpm_open(dev_t *devp, int flag, int otyp, cred_t *cred)
{
    char *myname = "tpm_open";
    int instance;
    tpm_state_t *tpm;

    ASSERT(devp != NULL);

    instance = getminor(*devp);
    if ((tpm = ddi_get_soft_state(statep, instance)) == NULL) {
        cmn_err(CE_WARN, "%s: stored pointer to tpm state is NULL",
            myname);
        return (ENXIO);
    }
    if (otyp != OTYP_CHR) {
        cmn_err(CE_WARN, "%s: otyp(%d) != OTYP_CHR(%d)",
            myname, otyp, OTYP_CHR);
        return (EINVAL);
    }
    mutex_enter(&tpm->pm_mutex);
    while (tpm->suspended)
        cv_wait(&tpm->suspend_cv, &tpm->pm_mutex);
    mutex_exit(&tpm->pm_mutex);

    mutex_enter(&tpm->dev_lock);
    if (tpm->dev_held) {
        cmn_err(CE_WARN, "%s: the device is already being used",
            myname);
        mutex_exit(&tpm->dev_lock);
        return (EBUSY);
    }

    /* The device is free so mark it busy */
    tpm->dev_held = 1;
    mutex_exit(&tpm->dev_lock);

    return (0);
}

/*ARGSUSED*/
static int
tpm_close(dev_t dev, int flag, int otyp, cred_t *cred)
{
    char *myname = "tpm_close";
    int instance;
    tpm_state_t *tpm;

    instance = getminor(dev);
    if ((tpm = ddi_get_soft_state(statep, instance)) == NULL) {
        cmn_err(CE_WARN, "%s: stored pointer to tpm state is NULL",
            myname);
        return (ENXIO);
    }
    if (otyp != OTYP_CHR) {
        cmn_err(CE_WARN, "%s: otyp(%d) != OTYP_CHR(%d)",
            myname, otyp, OTYP_CHR);
        return (EINVAL);
    }
    mutex_enter(&tpm->pm_mutex);
    while (tpm->suspended)
        cv_wait(&tpm->suspend_cv, &tpm->pm_mutex);
    mutex_exit(&tpm->pm_mutex);

    ASSERT(tpm->dev_held);

    mutex_enter(&tpm->dev_lock);
    ASSERT(mutex_owned(&tpm->dev_lock));
    tpm->dev_held = 0;
    mutex_exit(&tpm->dev_lock);

    return (0);
}

/*ARGSUSED*/
static int
tpm_read(dev_t dev, struct uio *uiop, cred_t *credp)
{
    int ret;
    uint32_t size;
    char *myname = "tpm_read";
    int instance;
    tpm_state_t *tpm;

    instance = getminor(dev);
    if ((tpm = ddi_get_soft_state(statep, instance)) == NULL) {
        cmn_err(CE_WARN, "%s: stored pointer to tpm state is NULL",
            myname);
        return (ENXIO);
    }
    if (uiop == NULL) {
        cmn_err(CE_WARN, "%s: passed in uiop is NULL", myname);
        return (EFAULT);
    }

    mutex_enter(&tpm->pm_mutex);
    while (tpm->suspended)
        cv_wait(&tpm->suspend_cv, &tpm->pm_mutex);
    mutex_exit(&tpm->pm_mutex);

    /* Receive the data after requiring the lock */
    ret = tpm_lock(tpm);

    /* Timeout reached */
    if (ret == ETIME)
        return (ret);

    if (uiop->uio_resid > tpm->bufsize) {
        cmn_err(CE_WARN, "%s: read_in data is bigger "
            "than tpm->bufsize:read in:%d, bufsiz:%d",
            myname, (int)uiop->uio_resid, (int)tpm->bufsize);
        ret = EIO;
        goto OUT;
    }

    ret = tis_recv_data(tpm, tpm->iobuf, tpm->bufsize);
    if (ret < TPM_HEADER_SIZE) {
        cmn_err(CE_WARN, "%s: tis_recv_data returned error", myname);
        ret = EIO;
        goto OUT;
    }

    size = load32(tpm->iobuf, 2);
    if (ret != size) {
        cmn_err(CE_WARN, "%s: tis_recv_data:"
            "expected size=%d, actually read=%d",
            myname, size, ret);
        ret = EIO;
        goto OUT;
    }

    /* Send the buffer from the kernel to the userspace */
    ret = uiomove(tpm->iobuf, size, UIO_READ, uiop);
    if (ret) {
        cmn_err(CE_WARN, "%s: uiomove returned error", myname);
        goto OUT;
    }

    /* Zeroize the buffer... */
    bzero(tpm->iobuf, tpm->bufsize);
    ret = DDI_SUCCESS;
OUT:
    /* We are done now: wake up the waiting threads */
    tpm_unlock(tpm);

    return (ret);
}

/*ARGSUSED*/
static int
tpm_write(dev_t dev, struct uio *uiop, cred_t *credp)
{
    int ret;
    size_t len;
    uint32_t size;
    char *myname = "tpm_write";
    int instance;
    tpm_state_t *tpm;

    instance = getminor(dev);
    if ((tpm = ddi_get_soft_state(statep, instance)) == NULL) {
        cmn_err(CE_WARN, "%s: stored pointer to tpm state is NULL",
            myname);
        return (ENXIO);
    }

    if (uiop == NULL) {
        cmn_err(CE_WARN, "%s: passed in uiop is NULL", myname);
        return (EFAULT);
    }

    mutex_enter(&tpm->pm_mutex);
    while (tpm->suspended)
        cv_wait(&tpm->suspend_cv, &tpm->pm_mutex);
    mutex_exit(&tpm->pm_mutex);

    len = uiop->uio_resid;
    if (len == 0) {
        cmn_err(CE_WARN, "%s: requested read of len 0", myname);
        return (0);
    }

    /* Get the lock for using iobuf */
    ret = tpm_lock(tpm);
    /* Timeout Reached */
    if (ret == ETIME)
        return (ret);

    /* Copy the header and parse the structure to find out the size... */
    ret = uiomove(tpm->iobuf, TPM_HEADER_SIZE, UIO_WRITE, uiop);
    if (ret) {
        cmn_err(CE_WARN, "%s: uiomove returned error"
            "while getting the the header",
            myname);
        goto OUT;
    }

    /* Get the buffersize from the command buffer structure */
    size = load32(tpm->iobuf, TPM_PARAMSIZE_OFFSET);

    /* Copy the command to the contiguous buffer */
    if (size > tpm->bufsize) {
        cmn_err(CE_WARN, "%s: size %d is greater than "
            "the tpm's input buffer size %d",
            myname, (int)size, (int)tpm->bufsize);
        ret = ENXIO;
        goto OUT;
    }

    /* Copy the buffer from the userspace to kernel */
    ret = uiomove(tpm->iobuf+TPM_HEADER_SIZE, size-TPM_HEADER_SIZE,
        UIO_WRITE, uiop);

    if (ret) {
        cmn_err(CE_WARN, "%s: uiomove returned error"
            "while getting the rest of the command", myname);
        goto OUT;
    }

    /* Send the command */
    ret = tis_send_data(tpm, tpm->iobuf, size);
    if (ret != DDI_SUCCESS) {
        cmn_err(CE_WARN, "%s: tis_send_data returned error", myname);
        ret = EFAULT;
        goto OUT;
    }

    /* Zeroize the buffer... */
    bzero(tpm->iobuf, tpm->bufsize);
    ret = DDI_SUCCESS;
OUT:
    tpm_unlock(tpm);
    return (ret);
}

/*
 * This is to deal with the contentions for the iobuf
 */
static inline int
tpm_lock(tpm_state_t *tpm)
{
    int ret;
    clock_t timeout;

    mutex_enter(&tpm->iobuf_lock);
    ASSERT(mutex_owned(&tpm->iobuf_lock));

    timeout = ddi_get_lbolt() + drv_usectohz(TPM_IO_TIMEOUT);

    /* Wait until the iobuf becomes free with the timeout */
    while (tpm->iobuf_inuse) {
        ret = cv_timedwait(&tpm->iobuf_cv, &tpm->iobuf_lock, timeout);
        if (ret <= 0) {
            /* Timeout reached */
            mutex_exit(&tpm->iobuf_lock);
            cmn_err(CE_WARN, "tpm_lock:iorequest timed out");
            return (ETIME);
        }
    }
    tpm->iobuf_inuse = 1;
    mutex_exit(&tpm->iobuf_lock);
    return (0);
}

/*
 * This is to deal with the contentions for the iobuf
 */
static inline void
tpm_unlock(tpm_state_t *tpm)
{
    /* Wake up the waiting threads */
    mutex_enter(&tpm->iobuf_lock);
    ASSERT(tpm->iobuf_inuse == 1 && mutex_owned(&tpm->iobuf_lock));
    tpm->iobuf_inuse = 0;
    cv_broadcast(&tpm->iobuf_cv);
    mutex_exit(&tpm->iobuf_lock);
}