[mirror_ubuntu-bionic-kernel.git] / drivers / char / tpm / xen-tpmfront.c

/*
 * Implementation of the Xen vTPM device frontend
 *
 * Author:  Daniel De Graaf <dgdegra@tycho.nsa.gov>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2,
 * as published by the Free Software Foundation.
 */
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <xen/xen.h>
#include <xen/events.h>
#include <xen/interface/io/tpmif.h>
#include <xen/grant_table.h>
#include <xen/xenbus.h>
#include <xen/page.h>
#include "tpm.h"
#include <xen/platform_pci.h>

struct tpm_private {
	struct tpm_chip *chip;
	struct xenbus_device *dev;

	struct vtpm_shared_page *shr;

	unsigned int evtchn;
	int ring_ref;
	domid_t backend_id;
};

enum status_bits {
	VTPM_STATUS_RUNNING  = 0x1,
	VTPM_STATUS_IDLE     = 0x2,
	VTPM_STATUS_RESULT   = 0x4,
	VTPM_STATUS_CANCELED = 0x8,
};

static u8 vtpm_status(struct tpm_chip *chip)
{
	struct tpm_private *priv = TPM_VPRIV(chip);
	switch (priv->shr->state) {
	case VTPM_STATE_IDLE:
		return VTPM_STATUS_IDLE | VTPM_STATUS_CANCELED;
	case VTPM_STATE_FINISH:
		return VTPM_STATUS_IDLE | VTPM_STATUS_RESULT;
	case VTPM_STATE_SUBMIT:
	case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
		return VTPM_STATUS_RUNNING;
	default:
		return 0;
	}
}

static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
{
	return status & VTPM_STATUS_CANCELED;
}

static void vtpm_cancel(struct tpm_chip *chip)
{
	struct tpm_private *priv = TPM_VPRIV(chip);
	priv->shr->state = VTPM_STATE_CANCEL;
	wmb();
	notify_remote_via_evtchn(priv->evtchn);
}

static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
{
	return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
}

static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct tpm_private *priv = TPM_VPRIV(chip);
	struct vtpm_shared_page *shr = priv->shr;
	unsigned int offset = shr_data_offset(shr);

	u32 ordinal;
	unsigned long duration;

	if (offset > PAGE_SIZE)
		return -EINVAL;

	if (offset + count > PAGE_SIZE)
		return -EINVAL;

	/* Wait for completion of any existing command or cancellation */
	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->vendor.timeout_c,
			&chip->vendor.read_queue, true) < 0) {
		vtpm_cancel(chip);
		return -ETIME;
	}

	memcpy(offset + (u8 *)shr, buf, count);
	shr->length = count;
	barrier();
	shr->state = VTPM_STATE_SUBMIT;
	wmb();
	notify_remote_via_evtchn(priv->evtchn);

	ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal);
	duration = tpm_calc_ordinal_duration(chip, ordinal);

	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
			&chip->vendor.read_queue, true) < 0) {
		/* got a signal or timeout, try to cancel */
		vtpm_cancel(chip);
		return -ETIME;
	}

	return count;
}

static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct tpm_private *priv = TPM_VPRIV(chip);
	struct vtpm_shared_page *shr = priv->shr;
	unsigned int offset = shr_data_offset(shr);
	size_t length = shr->length;

	if (shr->state == VTPM_STATE_IDLE)
		return -ECANCELED;

	/* In theory the wait at the end of _send makes this one unnecessary */
	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->vendor.timeout_c,
			&chip->vendor.read_queue, true) < 0) {
		vtpm_cancel(chip);
		return -ETIME;
	}

	if (offset > PAGE_SIZE)
		return -EIO;

	if (offset + length > PAGE_SIZE)
		length = PAGE_SIZE - offset;

	if (length > count)
		length = count;

	memcpy(buf, offset + (u8 *)shr, length);

	return length;
}

static const struct tpm_class_ops tpm_vtpm = {
	.status = vtpm_status,
	.recv = vtpm_recv,
	.send = vtpm_send,
	.cancel = vtpm_cancel,
	.req_complete_mask = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
	.req_complete_val  = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
	.req_canceled      = vtpm_req_canceled,
};

static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
{
	struct tpm_private *priv = dev_id;

	switch (priv->shr->state) {
	case VTPM_STATE_IDLE:
	case VTPM_STATE_FINISH:
		wake_up_interruptible(&priv->chip->vendor.read_queue);
		break;
	case VTPM_STATE_SUBMIT:
	case VTPM_STATE_CANCEL:
	default:
		break;
	}
	return IRQ_HANDLED;
}

static int setup_chip(struct device *dev, struct tpm_private *priv)
{
	struct tpm_chip *chip;

	chip = tpmm_chip_alloc(dev, &tpm_vtpm);
	if (IS_ERR(chip))
		return PTR_ERR(chip);

	init_waitqueue_head(&chip->vendor.read_queue);

	priv->chip = chip;
	TPM_VPRIV(chip) = priv;

	return 0;
}

/* caller must clean up in case of errors */
static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
{
	struct xenbus_transaction xbt;
	const char *message = NULL;
	int rv;
	grant_ref_t gref;

	priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
	if (!priv->shr) {
		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
		return -ENOMEM;
	}

	rv = xenbus_grant_ring(dev, &priv->shr, 1, &gref);
	if (rv < 0)
		return rv;

	priv->ring_ref = gref;

	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
	if (rv)
		return rv;

	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
				       "tpmif", priv);
	if (rv <= 0) {
		xenbus_dev_fatal(dev, rv, "allocating TPM irq");
		return rv;
	}
	priv->chip->vendor.irq = rv;

 again:
	rv = xenbus_transaction_start(&xbt);
	if (rv) {
		xenbus_dev_fatal(dev, rv, "starting transaction");
		return rv;
	}

	rv = xenbus_printf(xbt, dev->nodename,
			"ring-ref", "%u", priv->ring_ref);
	if (rv) {
		message = "writing ring-ref";
		goto abort_transaction;
	}

	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
			priv->evtchn);
	if (rv) {
		message = "writing event-channel";
		goto abort_transaction;
	}

	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
	if (rv) {
		message = "writing feature-protocol-v2";
		goto abort_transaction;
	}

	rv = xenbus_transaction_end(xbt, 0);
	if (rv == -EAGAIN)
		goto again;
	if (rv) {
		xenbus_dev_fatal(dev, rv, "completing transaction");
		return rv;
	}

	xenbus_switch_state(dev, XenbusStateInitialised);

	return 0;

 abort_transaction:
	xenbus_transaction_end(xbt, 1);
	if (message)
		xenbus_dev_error(dev, rv, "%s", message);

	return rv;
}

static void ring_free(struct tpm_private *priv)
{
	if (!priv)
		return;

	if (priv->ring_ref)
		gnttab_end_foreign_access(priv->ring_ref, 0,
				(unsigned long)priv->shr);
	else
		free_page((unsigned long)priv->shr);

	if (priv->chip && priv->chip->vendor.irq)
		unbind_from_irqhandler(priv->chip->vendor.irq, priv);

	kfree(priv);
}

static int tpmfront_probe(struct xenbus_device *dev,
		const struct xenbus_device_id *id)
{
	struct tpm_private *priv;
	struct tpm_chip *chip;
	int rv;

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv) {
		xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
		return -ENOMEM;
	}

	rv = setup_chip(&dev->dev, priv);
	if (rv) {
		kfree(priv);
		return rv;
	}

	rv = setup_ring(dev, priv);
	if (rv) {
		chip = dev_get_drvdata(&dev->dev);
		tpm_chip_unregister(chip);
		ring_free(priv);
		return rv;
	}

	tpm_get_timeouts(priv->chip);

	return tpm_chip_register(priv->chip);
}

static int tpmfront_remove(struct xenbus_device *dev)
{
	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
	struct tpm_private *priv = TPM_VPRIV(chip);
	tpm_chip_unregister(chip);
	ring_free(priv);
	TPM_VPRIV(chip) = NULL;
	return 0;
}

static int tpmfront_resume(struct xenbus_device *dev)
{
	/* A suspend/resume/migrate will interrupt a vTPM anyway */
	tpmfront_remove(dev);
	return tpmfront_probe(dev, NULL);
}

static void backend_changed(struct xenbus_device *dev,
		enum xenbus_state backend_state)
{
	int val;

	switch (backend_state) {
	case XenbusStateInitialised:
	case XenbusStateConnected:
		if (dev->state == XenbusStateConnected)
			break;

		if (xenbus_scanf(XBT_NIL, dev->otherend,
				"feature-protocol-v2", "%d", &val) < 0)
			val = 0;
		if (!val) {
			xenbus_dev_fatal(dev, -EINVAL,
					"vTPM protocol 2 required");
			return;
		}
		xenbus_switch_state(dev, XenbusStateConnected);
		break;

	case XenbusStateClosing:
	case XenbusStateClosed:
		device_unregister(&dev->dev);
		xenbus_frontend_closed(dev);
		break;
	default:
		break;
	}
}

static const struct xenbus_device_id tpmfront_ids[] = {
	{ "vtpm" },
	{ "" }
};
MODULE_ALIAS("xen:vtpm");

static struct xenbus_driver tpmfront_driver = {
	.ids = tpmfront_ids,
	.probe = tpmfront_probe,
	.remove = tpmfront_remove,
	.resume = tpmfront_resume,
	.otherend_changed = backend_changed,
};

static int __init xen_tpmfront_init(void)
{
	if (!xen_domain())
		return -ENODEV;

	if (!xen_has_pv_devices())
		return -ENODEV;

	return xenbus_register_frontend(&tpmfront_driver);
}
module_init(xen_tpmfront_init);

static void __exit xen_tpmfront_exit(void)
{
	xenbus_unregister_driver(&tpmfront_driver);
}
module_exit(xen_tpmfront_exit);

MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
MODULE_DESCRIPTION("Xen vTPM Driver");
MODULE_LICENSE("GPL");
Commit	Line	Data
e2683957 DDG	1	/*
	2	* Implementation of the Xen vTPM device frontend
	3	*
	4	* Author: Daniel De Graaf <dgdegra@tycho.nsa.gov>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2,
	8	* as published by the Free Software Foundation.
	9	*/
	10	#include <linux/errno.h>
	11	#include <linux/err.h>
	12	#include <linux/interrupt.h>
8702c675	13	#include <xen/xen.h>
e2683957 DDG	14	#include <xen/events.h>
	15	#include <xen/interface/io/tpmif.h>
	16	#include <xen/grant_table.h>
	17	#include <xen/xenbus.h>
	18	#include <xen/page.h>
	19	#include "tpm.h"
51c71a3b	20	#include <xen/platform_pci.h>
e2683957 DDG	21
	22	struct tpm_private {
	23	struct tpm_chip *chip;
	24	struct xenbus_device *dev;
	25
	26	struct vtpm_shared_page *shr;
	27
	28	unsigned int evtchn;
	29	int ring_ref;
	30	domid_t backend_id;
	31	};
	32
	33	enum status_bits {
	34	VTPM_STATUS_RUNNING = 0x1,
	35	VTPM_STATUS_IDLE = 0x2,
	36	VTPM_STATUS_RESULT = 0x4,
	37	VTPM_STATUS_CANCELED = 0x8,
	38	};
	39
	40	static u8 vtpm_status(struct tpm_chip *chip)
	41	{
	42	struct tpm_private *priv = TPM_VPRIV(chip);
	43	switch (priv->shr->state) {
	44	case VTPM_STATE_IDLE:
	45	return VTPM_STATUS_IDLE \| VTPM_STATUS_CANCELED;
	46	case VTPM_STATE_FINISH:
	47	return VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT;
	48	case VTPM_STATE_SUBMIT:
	49	case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
	50	return VTPM_STATUS_RUNNING;
	51	default:
	52	return 0;
	53	}
	54	}
	55
	56	static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
	57	{
	58	return status & VTPM_STATUS_CANCELED;
	59	}
	60
	61	static void vtpm_cancel(struct tpm_chip *chip)
	62	{
	63	struct tpm_private *priv = TPM_VPRIV(chip);
	64	priv->shr->state = VTPM_STATE_CANCEL;
	65	wmb();
	66	notify_remote_via_evtchn(priv->evtchn);
	67	}
	68
	69	static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
	70	{
	71	return sizeof(shr) + sizeof(u32) shr->nr_extra_pages;
	72	}
	73
	74	static int vtpm_send(struct tpm_chip chip, u8 buf, size_t count)
	75	{
	76	struct tpm_private *priv = TPM_VPRIV(chip);
	77	struct vtpm_shared_page *shr = priv->shr;
	78	unsigned int offset = shr_data_offset(shr);
	79
	80	u32 ordinal;
	81	unsigned long duration;
	82
	83	if (offset > PAGE_SIZE)
	84	return -EINVAL;
85
86	if (offset + count > PAGE_SIZE)
87	return -EINVAL;
88
89	/* Wait for completion of any existing command or cancellation */
90	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->vendor.timeout_c,
91	&chip->vendor.read_queue, true) < 0) {
92	vtpm_cancel(chip);
93	return -ETIME;
94	}
95
96	memcpy(offset + (u8 *)shr, buf, count);
97	shr->length = count;
98	barrier();
99	shr->state = VTPM_STATE_SUBMIT;
100	wmb();
101	notify_remote_via_evtchn(priv->evtchn);
102
103	ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal);
104	duration = tpm_calc_ordinal_duration(chip, ordinal);
105
106	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
107	&chip->vendor.read_queue, true) < 0) {
108	/* got a signal or timeout, try to cancel */
109	vtpm_cancel(chip);
110	return -ETIME;
111	}
112
113	return count;
114	}
115
116	static int vtpm_recv(struct tpm_chip chip, u8 buf, size_t count)
117	{
118	struct tpm_private *priv = TPM_VPRIV(chip);
119	struct vtpm_shared_page *shr = priv->shr;
120	unsigned int offset = shr_data_offset(shr);
121	size_t length = shr->length;
122
123	if (shr->state == VTPM_STATE_IDLE)
124	return -ECANCELED;
125
126	/* In theory the wait at the end of _send makes this one unnecessary */
127	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->vendor.timeout_c,
128	&chip->vendor.read_queue, true) < 0) {
129	vtpm_cancel(chip);
130	return -ETIME;
131	}
132
133	if (offset > PAGE_SIZE)
134	return -EIO;
135
136	if (offset + length > PAGE_SIZE)
137	length = PAGE_SIZE - offset;
138
139	if (length > count)
140	length = count;
141
142	memcpy(buf, offset + (u8 *)shr, length);
143
144	return length;
145	}
146
01ad1fa7	147	static const struct tpm_class_ops tpm_vtpm = {
e2683957 DDG	148	.status = vtpm_status,
	149	.recv = vtpm_recv,
	150	.send = vtpm_send,
	151	.cancel = vtpm_cancel,
	152	.req_complete_mask = VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT,
	153	.req_complete_val = VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT,
	154	.req_canceled = vtpm_req_canceled,
e2683957 DDG	155	};
	156
	157	static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
	158	{
	159	struct tpm_private *priv = dev_id;
	160
	161	switch (priv->shr->state) {
	162	case VTPM_STATE_IDLE:
	163	case VTPM_STATE_FINISH:
	164	wake_up_interruptible(&priv->chip->vendor.read_queue);
	165	break;
	166	case VTPM_STATE_SUBMIT:
	167	case VTPM_STATE_CANCEL:
	168	default:
	169	break;
	170	}
	171	return IRQ_HANDLED;
	172	}
	173
	174	static int setup_chip(struct device dev, struct tpm_private priv)
	175	{
	176	struct tpm_chip *chip;
	177
afb5abc2 JS	178	chip = tpmm_chip_alloc(dev, &tpm_vtpm);
	179	if (IS_ERR(chip))
	180	return PTR_ERR(chip);
e2683957 DDG	181
	182	init_waitqueue_head(&chip->vendor.read_queue);
	183
	184	priv->chip = chip;
	185	TPM_VPRIV(chip) = priv;
	186
	187	return 0;
	188	}
	189
	190	/* caller must clean up in case of errors */
	191	static int setup_ring(struct xenbus_device dev, struct tpm_private priv)
	192	{
	193	struct xenbus_transaction xbt;
	194	const char *message = NULL;
	195	int rv;
ccc9d90a	196	grant_ref_t gref;
e2683957 DDG	197
	198	priv->shr = (void *)__get_free_page(GFP_KERNEL\|__GFP_ZERO);
	199	if (!priv->shr) {
	200	xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
	201	return -ENOMEM;
	202	}
	203
ccc9d90a	204	rv = xenbus_grant_ring(dev, &priv->shr, 1, &gref);
e2683957 DDG	205	if (rv < 0)
	206	return rv;
	207
ccc9d90a	208	priv->ring_ref = gref;
e2683957 DDG	209
	210	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
	211	if (rv)
	212	return rv;
	213
	214	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
	215	"tpmif", priv);
	216	if (rv <= 0) {
	217	xenbus_dev_fatal(dev, rv, "allocating TPM irq");
	218	return rv;
	219	}
	220	priv->chip->vendor.irq = rv;
	221
	222	again:
	223	rv = xenbus_transaction_start(&xbt);
	224	if (rv) {
	225	xenbus_dev_fatal(dev, rv, "starting transaction");
	226	return rv;
	227	}
	228
	229	rv = xenbus_printf(xbt, dev->nodename,
	230	"ring-ref", "%u", priv->ring_ref);
	231	if (rv) {
	232	message = "writing ring-ref";
	233	goto abort_transaction;
	234	}
	235
	236	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
	237	priv->evtchn);
	238	if (rv) {
	239	message = "writing event-channel";
	240	goto abort_transaction;
	241	}
	242
	243	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
	244	if (rv) {
	245	message = "writing feature-protocol-v2";
	246	goto abort_transaction;
	247	}
	248
	249	rv = xenbus_transaction_end(xbt, 0);
	250	if (rv == -EAGAIN)
	251	goto again;
	252	if (rv) {
	253	xenbus_dev_fatal(dev, rv, "completing transaction");
	254	return rv;
	255	}
	256
	257	xenbus_switch_state(dev, XenbusStateInitialised);
	258
	259	return 0;
	260
	261	abort_transaction:
	262	xenbus_transaction_end(xbt, 1);
	263	if (message)
	264	xenbus_dev_error(dev, rv, "%s", message);
	265
	266	return rv;
	267	}
	268
	269	static void ring_free(struct tpm_private *priv)
	270	{
	271	if (!priv)
	272	return;
273
274	if (priv->ring_ref)
275	gnttab_end_foreign_access(priv->ring_ref, 0,
276	(unsigned long)priv->shr);
277	else
278	free_page((unsigned long)priv->shr);
279
280	if (priv->chip && priv->chip->vendor.irq)
281	unbind_from_irqhandler(priv->chip->vendor.irq, priv);
282
283	kfree(priv);
284	}
285
286	static int tpmfront_probe(struct xenbus_device *dev,
287	const struct xenbus_device_id *id)
288	{
289	struct tpm_private *priv;
afb5abc2	290	struct tpm_chip *chip;
e2683957 DDG	291	int rv;
	292
	293	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	294	if (!priv) {
	295	xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
	296	return -ENOMEM;
	297	}
	298
	299	rv = setup_chip(&dev->dev, priv);
	300	if (rv) {
	301	kfree(priv);
	302	return rv;
	303	}
	304
	305	rv = setup_ring(dev, priv);
	306	if (rv) {
afb5abc2 JS	307	chip = dev_get_drvdata(&dev->dev);
afb5abc2 JS	308	tpm_chip_unregister(chip);
e2683957 DDG	309	ring_free(priv);
	310	return rv;
	311	}
	312
	313	tpm_get_timeouts(priv->chip);
	314
afb5abc2	315	return tpm_chip_register(priv->chip);
e2683957 DDG	316	}
	317
	318	static int tpmfront_remove(struct xenbus_device *dev)
	319	{
	320	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
	321	struct tpm_private *priv = TPM_VPRIV(chip);
afb5abc2	322	tpm_chip_unregister(chip);
e2683957 DDG	323	ring_free(priv);
	324	TPM_VPRIV(chip) = NULL;
	325	return 0;
	326	}
	327
	328	static int tpmfront_resume(struct xenbus_device *dev)
	329	{
	330	/* A suspend/resume/migrate will interrupt a vTPM anyway */
	331	tpmfront_remove(dev);
	332	return tpmfront_probe(dev, NULL);
	333	}
	334
	335	static void backend_changed(struct xenbus_device *dev,
	336	enum xenbus_state backend_state)
	337	{
	338	int val;
	339
	340	switch (backend_state) {
	341	case XenbusStateInitialised:
	342	case XenbusStateConnected:
	343	if (dev->state == XenbusStateConnected)
	344	break;
	345
	346	if (xenbus_scanf(XBT_NIL, dev->otherend,
	347	"feature-protocol-v2", "%d", &val) < 0)
	348	val = 0;
	349	if (!val) {
	350	xenbus_dev_fatal(dev, -EINVAL,
	351	"vTPM protocol 2 required");
	352	return;
	353	}
	354	xenbus_switch_state(dev, XenbusStateConnected);
	355	break;
	356
	357	case XenbusStateClosing:
	358	case XenbusStateClosed:
	359	device_unregister(&dev->dev);
	360	xenbus_frontend_closed(dev);
	361	break;
	362	default:
	363	break;
	364	}
	365	}
	366
	367	static const struct xenbus_device_id tpmfront_ids[] = {
	368	{ "vtpm" },
	369	{ "" }
	370	};
	371	MODULE_ALIAS("xen:vtpm");
	372
95afae48 DV	373	static struct xenbus_driver tpmfront_driver = {
	374	.ids = tpmfront_ids,
	375	.probe = tpmfront_probe,
	376	.remove = tpmfront_remove,
	377	.resume = tpmfront_resume,
	378	.otherend_changed = backend_changed,
	379	};
e2683957 DDG	380
	381	static int __init xen_tpmfront_init(void)
	382	{
	383	if (!xen_domain())
	384	return -ENODEV;
	385
51c71a3b KRW	386	if (!xen_has_pv_devices())
	387	return -ENODEV;
	388
e2683957 DDG	389	return xenbus_register_frontend(&tpmfront_driver);
	390	}
	391	module_init(xen_tpmfront_init);
	392
	393	static void __exit xen_tpmfront_exit(void)
	394	{
	395	xenbus_unregister_driver(&tpmfront_driver);
	396	}
	397	module_exit(xen_tpmfront_exit);
	398
	399	MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
	400	MODULE_DESCRIPTION("Xen vTPM Driver");
	401	MODULE_LICENSE("GPL");