[mirror_ubuntu-hirsute-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;
	int irq;
};

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->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->irq)
		unbind_from_irqhandler(priv->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;
570a3609	31	int irq;
e2683957 DDG	32	};
	33
	34	enum status_bits {
	35	VTPM_STATUS_RUNNING = 0x1,
	36	VTPM_STATUS_IDLE = 0x2,
	37	VTPM_STATUS_RESULT = 0x4,
	38	VTPM_STATUS_CANCELED = 0x8,
	39	};
	40
	41	static u8 vtpm_status(struct tpm_chip *chip)
	42	{
	43	struct tpm_private *priv = TPM_VPRIV(chip);
	44	switch (priv->shr->state) {
	45	case VTPM_STATE_IDLE:
	46	return VTPM_STATUS_IDLE \| VTPM_STATUS_CANCELED;
	47	case VTPM_STATE_FINISH:
	48	return VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT;
	49	case VTPM_STATE_SUBMIT:
	50	case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
	51	return VTPM_STATUS_RUNNING;
	52	default:
	53	return 0;
	54	}
	55	}
	56
	57	static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
	58	{
	59	return status & VTPM_STATUS_CANCELED;
	60	}
	61
	62	static void vtpm_cancel(struct tpm_chip *chip)
	63	{
	64	struct tpm_private *priv = TPM_VPRIV(chip);
	65	priv->shr->state = VTPM_STATE_CANCEL;
	66	wmb();
	67	notify_remote_via_evtchn(priv->evtchn);
	68	}
	69
	70	static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
	71	{
	72	return sizeof(shr) + sizeof(u32) shr->nr_extra_pages;
	73	}
	74
	75	static int vtpm_send(struct tpm_chip chip, u8 buf, size_t count)
	76	{
	77	struct tpm_private *priv = TPM_VPRIV(chip);
	78	struct vtpm_shared_page *shr = priv->shr;
	79	unsigned int offset = shr_data_offset(shr);
	80
	81	u32 ordinal;
	82	unsigned long duration;
	83
	84	if (offset > PAGE_SIZE)
	85	return -EINVAL;
	86
	87	if (offset + count > PAGE_SIZE)
	88	return -EINVAL;
	89
	90	/* Wait for completion of any existing command or cancellation */
	91	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->vendor.timeout_c,
	92	&chip->vendor.read_queue, true) < 0) {
	93	vtpm_cancel(chip);
	94	return -ETIME;
	95	}
96
97	memcpy(offset + (u8 *)shr, buf, count);
98	shr->length = count;
99	barrier();
100	shr->state = VTPM_STATE_SUBMIT;
101	wmb();
102	notify_remote_via_evtchn(priv->evtchn);
103
104	ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal);
105	duration = tpm_calc_ordinal_duration(chip, ordinal);
106
107	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
108	&chip->vendor.read_queue, true) < 0) {
109	/* got a signal or timeout, try to cancel */
110	vtpm_cancel(chip);
111	return -ETIME;
112	}
113
114	return count;
115	}
116
117	static int vtpm_recv(struct tpm_chip chip, u8 buf, size_t count)
118	{
119	struct tpm_private *priv = TPM_VPRIV(chip);
120	struct vtpm_shared_page *shr = priv->shr;
121	unsigned int offset = shr_data_offset(shr);
122	size_t length = shr->length;
123
124	if (shr->state == VTPM_STATE_IDLE)
125	return -ECANCELED;
126
127	/* In theory the wait at the end of _send makes this one unnecessary */
128	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->vendor.timeout_c,
129	&chip->vendor.read_queue, true) < 0) {
130	vtpm_cancel(chip);
131	return -ETIME;
132	}
133
134	if (offset > PAGE_SIZE)
135	return -EIO;
136
137	if (offset + length > PAGE_SIZE)
138	length = PAGE_SIZE - offset;
139
140	if (length > count)
141	length = count;
142
143	memcpy(buf, offset + (u8 *)shr, length);
144
145	return length;
146	}
147
01ad1fa7	148	static const struct tpm_class_ops tpm_vtpm = {
e2683957 DDG	149	.status = vtpm_status,
	150	.recv = vtpm_recv,
	151	.send = vtpm_send,
	152	.cancel = vtpm_cancel,
	153	.req_complete_mask = VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT,
	154	.req_complete_val = VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT,
	155	.req_canceled = vtpm_req_canceled,
e2683957 DDG	156	};
	157
	158	static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
	159	{
	160	struct tpm_private *priv = dev_id;
	161
	162	switch (priv->shr->state) {
	163	case VTPM_STATE_IDLE:
	164	case VTPM_STATE_FINISH:
	165	wake_up_interruptible(&priv->chip->vendor.read_queue);
	166	break;
	167	case VTPM_STATE_SUBMIT:
	168	case VTPM_STATE_CANCEL:
	169	default:
	170	break;
	171	}
	172	return IRQ_HANDLED;
	173	}
	174
	175	static int setup_chip(struct device dev, struct tpm_private priv)
	176	{
	177	struct tpm_chip *chip;
	178
afb5abc2 JS	179	chip = tpmm_chip_alloc(dev, &tpm_vtpm);
	180	if (IS_ERR(chip))
	181	return PTR_ERR(chip);
e2683957 DDG	182
	183	init_waitqueue_head(&chip->vendor.read_queue);
	184
	185	priv->chip = chip;
	186	TPM_VPRIV(chip) = priv;
	187
	188	return 0;
	189	}
	190
	191	/* caller must clean up in case of errors */
	192	static int setup_ring(struct xenbus_device dev, struct tpm_private priv)
	193	{
	194	struct xenbus_transaction xbt;
	195	const char *message = NULL;
	196	int rv;
ccc9d90a	197	grant_ref_t gref;
e2683957 DDG	198
	199	priv->shr = (void *)__get_free_page(GFP_KERNEL\|__GFP_ZERO);
	200	if (!priv->shr) {
	201	xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
	202	return -ENOMEM;
	203	}
	204
ccc9d90a	205	rv = xenbus_grant_ring(dev, &priv->shr, 1, &gref);
e2683957 DDG	206	if (rv < 0)
	207	return rv;
	208
ccc9d90a	209	priv->ring_ref = gref;
e2683957 DDG	210
	211	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
	212	if (rv)
	213	return rv;
	214
	215	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
	216	"tpmif", priv);
	217	if (rv <= 0) {
	218	xenbus_dev_fatal(dev, rv, "allocating TPM irq");
	219	return rv;
	220	}
570a3609	221	priv->irq = rv;
e2683957 DDG	222
	223	again:
	224	rv = xenbus_transaction_start(&xbt);
	225	if (rv) {
	226	xenbus_dev_fatal(dev, rv, "starting transaction");
	227	return rv;
	228	}
	229
	230	rv = xenbus_printf(xbt, dev->nodename,
	231	"ring-ref", "%u", priv->ring_ref);
	232	if (rv) {
	233	message = "writing ring-ref";
	234	goto abort_transaction;
	235	}
	236
	237	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
	238	priv->evtchn);
	239	if (rv) {
	240	message = "writing event-channel";
	241	goto abort_transaction;
	242	}
	243
	244	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
	245	if (rv) {
	246	message = "writing feature-protocol-v2";
	247	goto abort_transaction;
	248	}
	249
	250	rv = xenbus_transaction_end(xbt, 0);
	251	if (rv == -EAGAIN)
	252	goto again;
	253	if (rv) {
	254	xenbus_dev_fatal(dev, rv, "completing transaction");
	255	return rv;
	256	}
	257
	258	xenbus_switch_state(dev, XenbusStateInitialised);
	259
	260	return 0;
	261
	262	abort_transaction:
	263	xenbus_transaction_end(xbt, 1);
	264	if (message)
	265	xenbus_dev_error(dev, rv, "%s", message);
	266
	267	return rv;
	268	}
	269
	270	static void ring_free(struct tpm_private *priv)
	271	{
	272	if (!priv)
	273	return;
	274
	275	if (priv->ring_ref)
	276	gnttab_end_foreign_access(priv->ring_ref, 0,
	277	(unsigned long)priv->shr);
	278	else
	279	free_page((unsigned long)priv->shr);
	280
570a3609 CR	281	if (priv->irq)
570a3609 CR	282	unbind_from_irqhandler(priv->irq, priv);
e2683957 DDG	283
	284	kfree(priv);
	285	}
	286
	287	static int tpmfront_probe(struct xenbus_device *dev,
	288	const struct xenbus_device_id *id)
	289	{
	290	struct tpm_private *priv;
afb5abc2	291	struct tpm_chip *chip;
e2683957 DDG	292	int rv;
	293
	294	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	295	if (!priv) {
	296	xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
	297	return -ENOMEM;
	298	}
	299
	300	rv = setup_chip(&dev->dev, priv);
	301	if (rv) {
	302	kfree(priv);
	303	return rv;
	304	}
	305
	306	rv = setup_ring(dev, priv);
	307	if (rv) {
afb5abc2 JS	308	chip = dev_get_drvdata(&dev->dev);
afb5abc2 JS	309	tpm_chip_unregister(chip);
e2683957 DDG	310	ring_free(priv);
	311	return rv;
	312	}
	313
	314	tpm_get_timeouts(priv->chip);
	315
afb5abc2	316	return tpm_chip_register(priv->chip);
e2683957 DDG	317	}
	318
	319	static int tpmfront_remove(struct xenbus_device *dev)
	320	{
	321	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
	322	struct tpm_private *priv = TPM_VPRIV(chip);
afb5abc2	323	tpm_chip_unregister(chip);
e2683957 DDG	324	ring_free(priv);
	325	TPM_VPRIV(chip) = NULL;
	326	return 0;
	327	}
	328
	329	static int tpmfront_resume(struct xenbus_device *dev)
	330	{
	331	/* A suspend/resume/migrate will interrupt a vTPM anyway */
	332	tpmfront_remove(dev);
	333	return tpmfront_probe(dev, NULL);
	334	}
	335
	336	static void backend_changed(struct xenbus_device *dev,
	337	enum xenbus_state backend_state)
	338	{
	339	int val;
	340
	341	switch (backend_state) {
	342	case XenbusStateInitialised:
	343	case XenbusStateConnected:
	344	if (dev->state == XenbusStateConnected)
	345	break;
	346
	347	if (xenbus_scanf(XBT_NIL, dev->otherend,
	348	"feature-protocol-v2", "%d", &val) < 0)
	349	val = 0;
	350	if (!val) {
	351	xenbus_dev_fatal(dev, -EINVAL,
	352	"vTPM protocol 2 required");
	353	return;
	354	}
	355	xenbus_switch_state(dev, XenbusStateConnected);
	356	break;
	357
	358	case XenbusStateClosing:
	359	case XenbusStateClosed:
	360	device_unregister(&dev->dev);
	361	xenbus_frontend_closed(dev);
	362	break;
	363	default:
	364	break;
	365	}
	366	}
	367
	368	static const struct xenbus_device_id tpmfront_ids[] = {
	369	{ "vtpm" },
	370	{ "" }
	371	};
	372	MODULE_ALIAS("xen:vtpm");
	373
95afae48 DV	374	static struct xenbus_driver tpmfront_driver = {
	375	.ids = tpmfront_ids,
	376	.probe = tpmfront_probe,
	377	.remove = tpmfront_remove,
	378	.resume = tpmfront_resume,
	379	.otherend_changed = backend_changed,
	380	};
e2683957 DDG	381
	382	static int __init xen_tpmfront_init(void)
	383	{
	384	if (!xen_domain())
	385	return -ENODEV;
	386
51c71a3b KRW	387	if (!xen_has_pv_devices())
	388	return -ENODEV;
	389
e2683957 DDG	390	return xenbus_register_frontend(&tpmfront_driver);
	391	}
	392	module_init(xen_tpmfront_init);
	393
	394	static void __exit xen_tpmfront_exit(void)
	395	{
	396	xenbus_unregister_driver(&tpmfront_driver);
	397	}
	398	module_exit(xen_tpmfront_exit);
	399
	400	MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
	401	MODULE_DESCRIPTION("Xen vTPM Driver");
	402	MODULE_LICENSE("GPL");