/******************************************************************************
 * tpmif.h
 *
 * TPM I/O interface for Xen guest OSes, v2
 *
 * This file is in the public domain.
 *
 */

#ifndef __XEN_PUBLIC_IO_TPMIF_H__
#define __XEN_PUBLIC_IO_TPMIF_H__

/*
 * Xenbus state machine
 *
 * Device open:
 *   1. Both ends start in XenbusStateInitialising
 *   2. Backend transitions to InitWait (frontend does not wait on this step)
 *   3. Frontend populates ring-ref, event-channel, feature-protocol-v2
 *   4. Frontend transitions to Initialised
 *   5. Backend maps grant and event channel, verifies feature-protocol-v2
 *   6. Backend transitions to Connected
 *   7. Frontend verifies feature-protocol-v2, transitions to Connected
 *
 * Device close:
 *   1. State is changed to XenbusStateClosing
 *   2. Frontend transitions to Closed
 *   3. Backend unmaps grant and event, changes state to InitWait
 */

enum vtpm_shared_page_state {
	VTPM_STATE_IDLE,         /* no contents / vTPM idle / cancel complete */
	VTPM_STATE_SUBMIT,       /* request ready / vTPM working */
	VTPM_STATE_FINISH,       /* response ready / vTPM idle */
	VTPM_STATE_CANCEL,       /* cancel requested / vTPM working */
};
/* The backend should only change state to IDLE or FINISH, while the
 * frontend should only change to SUBMIT or CANCEL. */


struct vtpm_shared_page {
	uint32_t length;         /* request/response length in bytes */

	uint8_t state;           /* enum vtpm_shared_page_state */
	uint8_t locality;        /* for the current request */
	uint8_t pad;

	uint8_t nr_extra_pages;  /* extra pages for long packets; may be zero */
	uint32_t extra_pages[0]; /* grant IDs; length in nr_extra_pages */
};

#endif