// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2004 IBM Corporation
 * Copyright (C) 2014 Intel Corporation
 *
 * Authors:
 * Leendert van Doorn <leendert@watson.ibm.com>
 * Dave Safford <safford@watson.ibm.com>
 * Reiner Sailer <sailer@watson.ibm.com>
 * Kylene Hall <kjhall@us.ibm.com>
 *
 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
 *
 * Device driver for TCG/TCPA TPM (trusted platform module).
 * Specifications at www.trustedcomputinggroup.org
 *
 * Note, the TPM chip is not interrupt driven (only polling)
 * and can have very long timeouts (minutes!). Hence the unusual
 * calls to msleep.
 */

#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/suspend.h>
#include <linux/freezer.h>
#include <linux/tpm_eventlog.h>

#include "tpm.h"

/*
 * Bug workaround - some TPM's don't flush the most
 * recently changed pcr on suspend, so force the flush
 * with an extend to the selected _unused_ non-volatile pcr.
 */
static u32 tpm_suspend_pcr;
module_param_named(suspend_pcr, tpm_suspend_pcr, uint, 0644);
MODULE_PARM_DESC(suspend_pcr,
                 "PCR to use for dummy writes to facilitate flush on suspend.");

/**
 * tpm_calc_ordinal_duration() - calculate the maximum command duration
 * @chip:    TPM chip to use.
 * @ordinal: TPM command ordinal.
 *
 * The function returns the maximum amount of time the chip could take
 * to return the result for a particular ordinal in jiffies.
 *
 * Return: A maximal duration time for an ordinal in jiffies.
 */
unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
{
        if (chip->flags & TPM_CHIP_FLAG_TPM2)
                return tpm2_calc_ordinal_duration(ordinal);
        else
                return tpm1_calc_ordinal_duration(chip, ordinal);
}
EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration);

static void tpm_chip_cancel(struct tpm_chip *chip)
{
        if (!chip->ops->cancel)
                return;

        chip->ops->cancel(chip);
}

static u8 tpm_chip_status(struct tpm_chip *chip)
{
        if (!chip->ops->status)
                return 0;

        return chip->ops->status(chip);
}

static bool tpm_chip_req_canceled(struct tpm_chip *chip, u8 status)
{
        if (!chip->ops->req_canceled)
                return false;

        return chip->ops->req_canceled(chip, status);
}

static bool tpm_transmit_completed(u8 status, struct tpm_chip *chip)
{
        u8 status_masked = status & chip->ops->req_complete_mask;

        return status_masked == chip->ops->req_complete_val;
}

static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
{
        struct tpm_header *header = buf;
        int rc;
        ssize_t len = 0;
        u32 count, ordinal;
        unsigned long stop;

        if (bufsiz < TPM_HEADER_SIZE)
                return -EINVAL;

        if (bufsiz > TPM_BUFSIZE)
                bufsiz = TPM_BUFSIZE;

        count = be32_to_cpu(header->length);
        ordinal = be32_to_cpu(header->ordinal);
        if (count == 0)
                return -ENODATA;
        if (count > bufsiz) {
                dev_err(&chip->dev,
                        "invalid count value %x %zx\n", count, bufsiz);
                return -E2BIG;
        }

        rc = chip->ops->send(chip, buf, bufsiz, count);
        if (rc < 0) {
                if (rc != -EPIPE)
                        dev_err(&chip->dev,
                                "%s: send(): error %d\n", __func__, rc);
                return rc;
        }

        /*
         * Synchronous devices return the response directly during the send()
         * call in the same buffer.
         */
        if (chip->flags & TPM_CHIP_FLAG_SYNC) {
                len = rc;
                rc = 0;
                goto out_sync;
        }

        /*
         * A sanity check. send() of asynchronous devices should just return
         * zero on success e.g. not the command length.
         */
        if (rc > 0) {
                dev_warn(&chip->dev,
                         "%s: send(): invalid value %d\n", __func__, rc);
                rc = 0;
        }

        if (chip->flags & TPM_CHIP_FLAG_IRQ)
                goto out_recv;

        stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
        do {
                u8 status = tpm_chip_status(chip);
                if (tpm_transmit_completed(status, chip))
                        goto out_recv;

                if (tpm_chip_req_canceled(chip, status)) {
                        dev_err(&chip->dev, "Operation Canceled\n");
                        return -ECANCELED;
                }

                tpm_msleep(TPM_TIMEOUT_POLL);
                rmb();
        } while (time_before(jiffies, stop));

        /*
         * Check for completion one more time, just in case the device reported
         * it while the driver was sleeping in the busy loop above.
         */
        if (tpm_transmit_completed(tpm_chip_status(chip), chip))
                goto out_recv;

        tpm_chip_cancel(chip);
        dev_err(&chip->dev, "Operation Timed out\n");
        return -ETIME;

out_recv:
        len = chip->ops->recv(chip, buf, bufsiz);
        if (len < 0) {
                rc = len;
                dev_err(&chip->dev, "tpm_transmit: tpm_recv: error %d\n", rc);
                return rc;
        }
out_sync:
        if (len < TPM_HEADER_SIZE || len != be32_to_cpu(header->length))
                rc = -EFAULT;

        return rc ? rc : len;
}

/**
 * tpm_transmit - Internal kernel interface to transmit TPM commands.
 * @chip:       a TPM chip to use
 * @buf:        a TPM command buffer
 * @bufsiz:     length of the TPM command buffer
 *
 * A wrapper around tpm_try_transmit() that handles TPM2_RC_RETRY returns from
 * the TPM and retransmits the command after a delay up to a maximum wait of
 * TPM2_DURATION_LONG.
 *
 * Note that TPM 1.x never returns TPM2_RC_RETRY so the retry logic is TPM 2.0
 * only.
 *
 * Return:
 * * The response length        - OK
 * * -errno                     - A system error
 */
ssize_t tpm_transmit(struct tpm_chip *chip, u8 *buf, size_t bufsiz)
{
        struct tpm_header *header = (struct tpm_header *)buf;
        /* space for header and handles */
        u8 save[TPM_HEADER_SIZE + 3*sizeof(u32)];
        unsigned int delay_msec = TPM2_DURATION_SHORT;
        u32 rc = 0;
        ssize_t ret;
        const size_t save_size = min(sizeof(save), bufsiz);
        /* the command code is where the return code will be */
        u32 cc = be32_to_cpu(header->return_code);

        /*
         * Subtlety here: if we have a space, the handles will be
         * transformed, so when we restore the header we also have to
         * restore the handles.
         */
        memcpy(save, buf, save_size);

        for (;;) {
                ret = tpm_try_transmit(chip, buf, bufsiz);
                if (ret < 0)
                        break;
                rc = be32_to_cpu(header->return_code);
                if (rc != TPM2_RC_RETRY && rc != TPM2_RC_TESTING)
                        break;
                /*
                 * return immediately if self test returns test
                 * still running to shorten boot time.
                 */
                if (rc == TPM2_RC_TESTING && cc == TPM2_CC_SELF_TEST)
                        break;

                if (delay_msec > TPM2_DURATION_LONG) {
                        if (rc == TPM2_RC_RETRY)
                                dev_err(&chip->dev, "in retry loop\n");
                        else
                                dev_err(&chip->dev,
                                        "self test is still running\n");
                        break;
                }
                tpm_msleep(delay_msec);
                delay_msec *= 2;
                memcpy(buf, save, save_size);
        }
        return ret;
}

/**
 * tpm_transmit_cmd - send a tpm command to the device
 * @chip:                       a TPM chip to use
 * @buf:                        a TPM command buffer
 * @min_rsp_body_length:        minimum expected length of response body
 * @desc:                       command description used in the error message
 *
 * Return:
 * * 0          - OK
 * * -errno     - A system error
 * * TPM_RC     - A TPM error
 */
ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
                         size_t min_rsp_body_length, const char *desc)
{
        const struct tpm_header *header = (struct tpm_header *)buf->data;
        int err;
        ssize_t len;

        len = tpm_transmit(chip, buf->data, PAGE_SIZE);
        if (len <  0)
                return len;

        err = be32_to_cpu(header->return_code);
        if (err != 0 && err != TPM_ERR_DISABLED && err != TPM_ERR_DEACTIVATED
            && err != TPM2_RC_TESTING && desc)
                dev_err(&chip->dev, "A TPM error (%d) occurred %s\n", err,
                        desc);
        if (err)
                return err;

        if (len < min_rsp_body_length + TPM_HEADER_SIZE)
                return -EFAULT;

        buf->length = len;
        return 0;
}
EXPORT_SYMBOL_GPL(tpm_transmit_cmd);

int tpm_get_timeouts(struct tpm_chip *chip)
{
        if (chip->flags & TPM_CHIP_FLAG_HAVE_TIMEOUTS)
                return 0;

        if (chip->flags & TPM_CHIP_FLAG_TPM2)
                return tpm2_get_timeouts(chip);
        else
                return tpm1_get_timeouts(chip);
}
EXPORT_SYMBOL_GPL(tpm_get_timeouts);

/**
 * tpm_is_tpm2 - do we a have a TPM2 chip?
 * @chip:       a &struct tpm_chip instance, %NULL for the default chip
 *
 * Return:
 * 1 if we have a TPM2 chip.
 * 0 if we don't have a TPM2 chip.
 * A negative number for system errors (errno).
 */
int tpm_is_tpm2(struct tpm_chip *chip)
{
        int rc;

        if (!chip)
                return -ENODEV;

        rc = tpm_try_get_ops(chip);
        if (rc)
                return rc;

        rc = (chip->flags & TPM_CHIP_FLAG_TPM2) != 0;

        tpm_put_ops(chip);

        return rc;
}
EXPORT_SYMBOL_GPL(tpm_is_tpm2);

/**
 * tpm_pcr_read - read a PCR value from SHA1 bank
 * @chip:       a &struct tpm_chip instance, %NULL for the default chip
 * @pcr_idx:    the PCR to be retrieved
 * @digest:     the PCR bank and buffer current PCR value is written to
 *
 * Return: same as with tpm_transmit_cmd()
 */
int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
                 struct tpm_digest *digest)
{
        int rc;

        if (!chip)
                return -ENODEV;

        rc = tpm_try_get_ops(chip);
        if (rc)
                return rc;

        if (chip->flags & TPM_CHIP_FLAG_TPM2)
                rc = tpm2_pcr_read(chip, pcr_idx, digest, NULL);
        else
                rc = tpm1_pcr_read(chip, pcr_idx, digest->digest);

        tpm_put_ops(chip);
        return rc;
}
EXPORT_SYMBOL_GPL(tpm_pcr_read);

/**
 * tpm_pcr_extend - extend a PCR value in SHA1 bank.
 * @chip:       a &struct tpm_chip instance, %NULL for the default chip
 * @pcr_idx:    the PCR to be retrieved
 * @digests:    array of tpm_digest structures used to extend PCRs
 *
 * Note: callers must pass a digest for every allocated PCR bank, in the same
 * order of the banks in chip->allocated_banks.
 *
 * Return: same as with tpm_transmit_cmd()
 */
int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
                   struct tpm_digest *digests)
{
        int rc;
        int i;

        if (!chip)
                return -ENODEV;

        rc = tpm_try_get_ops(chip);
        if (rc)
                return rc;

        for (i = 0; i < chip->nr_allocated_banks; i++) {
                if (digests[i].alg_id != chip->allocated_banks[i].alg_id) {
                        rc = -EINVAL;
                        goto out;
                }
        }

        if (chip->flags & TPM_CHIP_FLAG_TPM2) {
                rc = tpm2_pcr_extend(chip, pcr_idx, digests);
                goto out;
        }

        rc = tpm1_pcr_extend(chip, pcr_idx, digests[0].digest,
                             "attempting extend a PCR value");

out:
        tpm_put_ops(chip);
        return rc;
}
EXPORT_SYMBOL_GPL(tpm_pcr_extend);

int tpm_auto_startup(struct tpm_chip *chip)
{
        int rc;

        if (!(chip->ops->flags & TPM_OPS_AUTO_STARTUP))
                return 0;

        if (chip->flags & TPM_CHIP_FLAG_TPM2)
                rc = tpm2_auto_startup(chip);
        else
                rc = tpm1_auto_startup(chip);

        return rc;
}

/*
 * We are about to suspend. Save the TPM state
 * so that it can be restored.
 */
int tpm_pm_suspend(struct device *dev)
{
        struct tpm_chip *chip = dev_get_drvdata(dev);
        int rc = 0;

        if (!chip)
                return -ENODEV;

        rc = tpm_try_get_ops(chip);
        if (rc) {
                /* Can be safely set out of locks, as no action cannot race: */
                chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
                goto out;
        }

        if (chip->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
                goto suspended;

        if ((chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED) &&
            !pm_suspend_via_firmware())
                goto suspended;

        if (chip->flags & TPM_CHIP_FLAG_TPM2) {
                tpm2_end_auth_session(chip);
                tpm2_shutdown(chip, TPM2_SU_STATE);
                goto suspended;
        }

        rc = tpm1_pm_suspend(chip, tpm_suspend_pcr);

suspended:
        chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
        tpm_put_ops(chip);

out:
        if (rc)
                dev_err(dev, "Ignoring error %d while suspending\n", rc);
        return 0;
}
EXPORT_SYMBOL_GPL(tpm_pm_suspend);

/*
 * Resume from a power safe. The BIOS already restored
 * the TPM state.
 */
int tpm_pm_resume(struct device *dev)
{
        struct tpm_chip *chip = dev_get_drvdata(dev);

        if (chip == NULL)
                return -ENODEV;

        chip->flags &= ~TPM_CHIP_FLAG_SUSPENDED;

        /*
         * Guarantee that SUSPENDED is written last, so that hwrng does not
         * activate before the chip has been fully resumed.
         */
        wmb();

        return 0;
}
EXPORT_SYMBOL_GPL(tpm_pm_resume);

/**
 * tpm_get_random() - get random bytes from the TPM's RNG
 * @chip:       a &struct tpm_chip instance, %NULL for the default chip
 * @out:        destination buffer for the random bytes
 * @max:        the max number of bytes to write to @out
 *
 * Return: number of random bytes read or a negative error value.
 */
int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max)
{
        int rc;

        if (!out || max > TPM_MAX_RNG_DATA)
                return -EINVAL;

        if (!chip)
                return -ENODEV;

        rc = tpm_try_get_ops(chip);
        if (rc)
                return rc;

        if (chip->flags & TPM_CHIP_FLAG_TPM2)
                rc = tpm2_get_random(chip, out, max);
        else
                rc = tpm1_get_random(chip, out, max);

        tpm_put_ops(chip);
        return rc;
}
EXPORT_SYMBOL_GPL(tpm_get_random);

static int __init tpm_init(void)
{
        int rc;

        rc = class_register(&tpm_class);
        if (rc) {
                pr_err("couldn't create tpm class\n");
                return rc;
        }

        rc = class_register(&tpmrm_class);
        if (rc) {
                pr_err("couldn't create tpmrm class\n");
                goto out_destroy_tpm_class;
        }

        rc = alloc_chrdev_region(&tpm_devt, 0, 2*TPM_NUM_DEVICES, "tpm");
        if (rc < 0) {
                pr_err("tpm: failed to allocate char dev region\n");
                goto out_destroy_tpmrm_class;
        }

        rc = tpm_dev_common_init();
        if (rc) {
                pr_err("tpm: failed to allocate char dev region\n");
                goto out_unreg_chrdev;
        }

        return 0;

out_unreg_chrdev:
        unregister_chrdev_region(tpm_devt, 2 * TPM_NUM_DEVICES);
out_destroy_tpmrm_class:
        class_unregister(&tpmrm_class);
out_destroy_tpm_class:
        class_unregister(&tpm_class);

        return rc;
}

static void __exit tpm_exit(void)
{
        idr_destroy(&dev_nums_idr);
        class_unregister(&tpm_class);
        class_unregister(&tpmrm_class);
        unregister_chrdev_region(tpm_devt, 2*TPM_NUM_DEVICES);
        tpm_dev_common_exit();
}

subsys_initcall(tpm_init);
module_exit(tpm_exit);

MODULE_AUTHOR("Leendert van Doorn <leendert@watson.ibm.com>");
MODULE_DESCRIPTION("TPM Driver");
MODULE_VERSION("2.0");
MODULE_LICENSE("GPL");