[mirror_ubuntu-kernels.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 <linux/freezer.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;
	wait_queue_head_t read_queue;
};

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

static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
					bool check_cancel, bool *canceled)
{
	u8 status = chip->ops->status(chip);

	*canceled = false;
	if ((status & mask) == mask)
		return true;
	if (check_cancel && chip->ops->req_canceled(chip, status)) {
		*canceled = true;
		return true;
	}
	return false;
}

static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
		unsigned long timeout, wait_queue_head_t *queue,
		bool check_cancel)
{
	unsigned long stop;
	long rc;
	u8 status;
	bool canceled = false;

	/* check current status */
	status = chip->ops->status(chip);
	if ((status & mask) == mask)
		return 0;

	stop = jiffies + timeout;

	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
again:
		timeout = stop - jiffies;
		if ((long)timeout <= 0)
			return -ETIME;
		rc = wait_event_interruptible_timeout(*queue,
			wait_for_tpm_stat_cond(chip, mask, check_cancel,
					       &canceled),
			timeout);
		if (rc > 0) {
			if (canceled)
				return -ECANCELED;
			return 0;
		}
		if (rc == -ERESTARTSYS && freezing(current)) {
			clear_thread_flag(TIF_SIGPENDING);
			goto again;
		}
	} else {
		do {
			tpm_msleep(TPM_TIMEOUT);
			status = chip->ops->status(chip);
			if ((status & mask) == mask)
				return 0;
		} while (time_before(jiffies, stop));
	}
	return -ETIME;
}

static u8 vtpm_status(struct tpm_chip *chip)
{
	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
	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 = dev_get_drvdata(&chip->dev);
	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 = dev_get_drvdata(&chip->dev);
	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->timeout_c,
			&priv->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_header *)buf)->ordinal);
	duration = tpm_calc_ordinal_duration(chip, ordinal);

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

	return 0;
}

static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
	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->timeout_c,
			&priv->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->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(&priv->read_queue);

	priv->chip = chip;
	dev_set_drvdata(&chip->dev, 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;
	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) {
		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 = dev_get_drvdata(&chip->dev);
	tpm_chip_unregister(chip);
	ring_free(priv);
	dev_set_drvdata(&chip->dev, 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)
{
	switch (backend_state) {
	case XenbusStateInitialised:
	case XenbusStateConnected:
		if (dev->state == XenbusStateConnected)
			break;

		if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
					  0)) {
			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>
87cdfdd1	13	#include <linux/freezer.h>
8702c675	14	#include <xen/xen.h>
e2683957 DDG	15	#include <xen/events.h>
	16	#include <xen/interface/io/tpmif.h>
	17	#include <xen/grant_table.h>
	18	#include <xen/xenbus.h>
	19	#include <xen/page.h>
	20	#include "tpm.h"
51c71a3b	21	#include <xen/platform_pci.h>
e2683957 DDG	22
	23	struct tpm_private {
	24	struct tpm_chip *chip;
	25	struct xenbus_device *dev;
	26
	27	struct vtpm_shared_page *shr;
	28
	29	unsigned int evtchn;
	30	int ring_ref;
	31	domid_t backend_id;
570a3609	32	int irq;
6e599f6f	33	wait_queue_head_t read_queue;
e2683957 DDG	34	};
	35
	36	enum status_bits {
	37	VTPM_STATUS_RUNNING = 0x1,
	38	VTPM_STATUS_IDLE = 0x2,
	39	VTPM_STATUS_RESULT = 0x4,
	40	VTPM_STATUS_CANCELED = 0x8,
	41	};
	42
87cdfdd1 NJ	43	static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
	44	bool check_cancel, bool *canceled)
	45	{
	46	u8 status = chip->ops->status(chip);
	47
	48	*canceled = false;
	49	if ((status & mask) == mask)
	50	return true;
	51	if (check_cancel && chip->ops->req_canceled(chip, status)) {
	52	*canceled = true;
	53	return true;
	54	}
	55	return false;
	56	}
	57
	58	static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
	59	unsigned long timeout, wait_queue_head_t *queue,
	60	bool check_cancel)
	61	{
	62	unsigned long stop;
	63	long rc;
	64	u8 status;
	65	bool canceled = false;
	66
	67	/* check current status */
	68	status = chip->ops->status(chip);
	69	if ((status & mask) == mask)
	70	return 0;
	71
	72	stop = jiffies + timeout;
	73
	74	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
	75	again:
	76	timeout = stop - jiffies;
	77	if ((long)timeout <= 0)
	78	return -ETIME;
	79	rc = wait_event_interruptible_timeout(*queue,
	80	wait_for_tpm_stat_cond(chip, mask, check_cancel,
	81	&canceled),
	82	timeout);
	83	if (rc > 0) {
	84	if (canceled)
	85	return -ECANCELED;
	86	return 0;
	87	}
	88	if (rc == -ERESTARTSYS && freezing(current)) {
	89	clear_thread_flag(TIF_SIGPENDING);
	90	goto again;
	91	}
	92	} else {
	93	do {
	94	tpm_msleep(TPM_TIMEOUT);
	95	status = chip->ops->status(chip);
	96	if ((status & mask) == mask)
	97	return 0;
	98	} while (time_before(jiffies, stop));
	99	}
	100	return -ETIME;
	101	}
	102
e2683957 DDG	103	static u8 vtpm_status(struct tpm_chip *chip)
e2683957 DDG	104	{
9e0d39d8	105	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
e2683957 DDG	106	switch (priv->shr->state) {
	107	case VTPM_STATE_IDLE:
	108	return VTPM_STATUS_IDLE \| VTPM_STATUS_CANCELED;
	109	case VTPM_STATE_FINISH:
	110	return VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT;
	111	case VTPM_STATE_SUBMIT:
	112	case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
	113	return VTPM_STATUS_RUNNING;
	114	default:
	115	return 0;
	116	}
	117	}
	118
	119	static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
	120	{
	121	return status & VTPM_STATUS_CANCELED;
	122	}
	123
	124	static void vtpm_cancel(struct tpm_chip *chip)
	125	{
9e0d39d8	126	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
e2683957 DDG	127	priv->shr->state = VTPM_STATE_CANCEL;
	128	wmb();
	129	notify_remote_via_evtchn(priv->evtchn);
	130	}
	131
	132	static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
	133	{
	134	return sizeof(shr) + sizeof(u32) shr->nr_extra_pages;
	135	}
	136
	137	static int vtpm_send(struct tpm_chip chip, u8 buf, size_t count)
	138	{
9e0d39d8	139	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
e2683957 DDG	140	struct vtpm_shared_page *shr = priv->shr;
	141	unsigned int offset = shr_data_offset(shr);
	142
	143	u32 ordinal;
	144	unsigned long duration;
	145
	146	if (offset > PAGE_SIZE)
	147	return -EINVAL;
	148
	149	if (offset + count > PAGE_SIZE)
	150	return -EINVAL;
	151
	152	/* Wait for completion of any existing command or cancellation */
af782f33	153	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->timeout_c,
6e599f6f	154	&priv->read_queue, true) < 0) {
e2683957 DDG	155	vtpm_cancel(chip);
	156	return -ETIME;
	157	}
	158
	159	memcpy(offset + (u8 *)shr, buf, count);
	160	shr->length = count;
	161	barrier();
	162	shr->state = VTPM_STATE_SUBMIT;
	163	wmb();
	164	notify_remote_via_evtchn(priv->evtchn);
	165
b34b77a9	166	ordinal = be32_to_cpu(((struct tpm_header *)buf)->ordinal);
e2683957 DDG	167	duration = tpm_calc_ordinal_duration(chip, ordinal);
	168
	169	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
6e599f6f	170	&priv->read_queue, true) < 0) {
e2683957 DDG	171	/* got a signal or timeout, try to cancel */
	172	vtpm_cancel(chip);
	173	return -ETIME;
	174	}
	175
f5595f5b	176	return 0;
e2683957 DDG	177	}
	178
	179	static int vtpm_recv(struct tpm_chip chip, u8 buf, size_t count)
	180	{
9e0d39d8	181	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
e2683957 DDG	182	struct vtpm_shared_page *shr = priv->shr;
	183	unsigned int offset = shr_data_offset(shr);
	184	size_t length = shr->length;
	185
	186	if (shr->state == VTPM_STATE_IDLE)
	187	return -ECANCELED;
	188
	189	/* In theory the wait at the end of _send makes this one unnecessary */
af782f33	190	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->timeout_c,
6e599f6f	191	&priv->read_queue, true) < 0) {
e2683957 DDG	192	vtpm_cancel(chip);
	193	return -ETIME;
	194	}
	195
	196	if (offset > PAGE_SIZE)
	197	return -EIO;
	198
	199	if (offset + length > PAGE_SIZE)
	200	length = PAGE_SIZE - offset;
	201
	202	if (length > count)
	203	length = count;
	204
	205	memcpy(buf, offset + (u8 *)shr, length);
	206
	207	return length;
	208	}
	209
01ad1fa7	210	static const struct tpm_class_ops tpm_vtpm = {
e2683957 DDG	211	.status = vtpm_status,
	212	.recv = vtpm_recv,
	213	.send = vtpm_send,
	214	.cancel = vtpm_cancel,
	215	.req_complete_mask = VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT,
	216	.req_complete_val = VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT,
	217	.req_canceled = vtpm_req_canceled,
e2683957 DDG	218	};
	219
	220	static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
	221	{
	222	struct tpm_private *priv = dev_id;
	223
	224	switch (priv->shr->state) {
	225	case VTPM_STATE_IDLE:
	226	case VTPM_STATE_FINISH:
6e599f6f	227	wake_up_interruptible(&priv->read_queue);
e2683957 DDG	228	break;
	229	case VTPM_STATE_SUBMIT:
	230	case VTPM_STATE_CANCEL:
	231	default:
	232	break;
	233	}
	234	return IRQ_HANDLED;
	235	}
	236
	237	static int setup_chip(struct device dev, struct tpm_private priv)
	238	{
	239	struct tpm_chip *chip;
	240
afb5abc2 JS	241	chip = tpmm_chip_alloc(dev, &tpm_vtpm);
	242	if (IS_ERR(chip))
	243	return PTR_ERR(chip);
e2683957	244
6e599f6f	245	init_waitqueue_head(&priv->read_queue);
e2683957 DDG	246
e2683957 DDG	247	priv->chip = chip;
9e0d39d8	248	dev_set_drvdata(&chip->dev, priv);
e2683957 DDG	249
	250	return 0;
	251	}
	252
	253	/* caller must clean up in case of errors */
	254	static int setup_ring(struct xenbus_device dev, struct tpm_private priv)
	255	{
	256	struct xenbus_transaction xbt;
	257	const char *message = NULL;
	258	int rv;
ccc9d90a	259	grant_ref_t gref;
e2683957 DDG	260
	261	priv->shr = (void *)__get_free_page(GFP_KERNEL\|__GFP_ZERO);
	262	if (!priv->shr) {
	263	xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
	264	return -ENOMEM;
	265	}
	266
e487a0f5	267	rv = xenbus_grant_ring(dev, priv->shr, 1, &gref);
e2683957 DDG	268	if (rv < 0)
	269	return rv;
	270
ccc9d90a	271	priv->ring_ref = gref;
e2683957 DDG	272
	273	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
	274	if (rv)
	275	return rv;
	276
	277	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
	278	"tpmif", priv);
	279	if (rv <= 0) {
	280	xenbus_dev_fatal(dev, rv, "allocating TPM irq");
	281	return rv;
	282	}
570a3609	283	priv->irq = rv;
e2683957 DDG	284
	285	again:
	286	rv = xenbus_transaction_start(&xbt);
	287	if (rv) {
	288	xenbus_dev_fatal(dev, rv, "starting transaction");
	289	return rv;
	290	}
	291
	292	rv = xenbus_printf(xbt, dev->nodename,
	293	"ring-ref", "%u", priv->ring_ref);
	294	if (rv) {
	295	message = "writing ring-ref";
	296	goto abort_transaction;
	297	}
	298
	299	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
	300	priv->evtchn);
	301	if (rv) {
	302	message = "writing event-channel";
	303	goto abort_transaction;
	304	}
	305
	306	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
	307	if (rv) {
	308	message = "writing feature-protocol-v2";
	309	goto abort_transaction;
	310	}
	311
	312	rv = xenbus_transaction_end(xbt, 0);
	313	if (rv == -EAGAIN)
	314	goto again;
	315	if (rv) {
	316	xenbus_dev_fatal(dev, rv, "completing transaction");
	317	return rv;
	318	}
	319
	320	xenbus_switch_state(dev, XenbusStateInitialised);
	321
	322	return 0;
	323
	324	abort_transaction:
	325	xenbus_transaction_end(xbt, 1);
	326	if (message)
	327	xenbus_dev_error(dev, rv, "%s", message);
	328
	329	return rv;
	330	}
	331
	332	static void ring_free(struct tpm_private *priv)
	333	{
	334	if (!priv)
	335	return;
	336
	337	if (priv->ring_ref)
	338	gnttab_end_foreign_access(priv->ring_ref, 0,
	339	(unsigned long)priv->shr);
	340	else
	341	free_page((unsigned long)priv->shr);
	342
570a3609 CR	343	if (priv->irq)
570a3609 CR	344	unbind_from_irqhandler(priv->irq, priv);
e2683957 DDG	345
	346	kfree(priv);
	347	}
	348
	349	static int tpmfront_probe(struct xenbus_device *dev,
	350	const struct xenbus_device_id *id)
	351	{
	352	struct tpm_private *priv;
	353	int rv;
	354
	355	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	356	if (!priv) {
	357	xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
	358	return -ENOMEM;
	359	}
	360
	361	rv = setup_chip(&dev->dev, priv);
	362	if (rv) {
	363	kfree(priv);
	364	return rv;
	365	}
	366
	367	rv = setup_ring(dev, priv);
	368	if (rv) {
e2683957 DDG	369	ring_free(priv);
	370	return rv;
	371	}
	372
	373	tpm_get_timeouts(priv->chip);
	374
afb5abc2	375	return tpm_chip_register(priv->chip);
e2683957 DDG	376	}
	377
	378	static int tpmfront_remove(struct xenbus_device *dev)
	379	{
	380	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
9e0d39d8	381	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
afb5abc2	382	tpm_chip_unregister(chip);
e2683957	383	ring_free(priv);
9e0d39d8	384	dev_set_drvdata(&chip->dev, NULL);
e2683957 DDG	385	return 0;
	386	}
	387
	388	static int tpmfront_resume(struct xenbus_device *dev)
	389	{
	390	/* A suspend/resume/migrate will interrupt a vTPM anyway */
	391	tpmfront_remove(dev);
	392	return tpmfront_probe(dev, NULL);
	393	}
	394
	395	static void backend_changed(struct xenbus_device *dev,
	396	enum xenbus_state backend_state)
	397	{
e2683957 DDG	398	switch (backend_state) {
	399	case XenbusStateInitialised:
	400	case XenbusStateConnected:
	401	if (dev->state == XenbusStateConnected)
	402	break;
	403
02409334 JG	404	if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
02409334 JG	405	0)) {
e2683957 DDG	406	xenbus_dev_fatal(dev, -EINVAL,
	407	"vTPM protocol 2 required");
	408	return;
	409	}
	410	xenbus_switch_state(dev, XenbusStateConnected);
	411	break;
	412
	413	case XenbusStateClosing:
	414	case XenbusStateClosed:
	415	device_unregister(&dev->dev);
	416	xenbus_frontend_closed(dev);
	417	break;
	418	default:
	419	break;
	420	}
	421	}
	422
	423	static const struct xenbus_device_id tpmfront_ids[] = {
	424	{ "vtpm" },
	425	{ "" }
	426	};
	427	MODULE_ALIAS("xen:vtpm");
	428
95afae48 DV	429	static struct xenbus_driver tpmfront_driver = {
	430	.ids = tpmfront_ids,
	431	.probe = tpmfront_probe,
	432	.remove = tpmfront_remove,
	433	.resume = tpmfront_resume,
	434	.otherend_changed = backend_changed,
	435	};
e2683957 DDG	436
	437	static int __init xen_tpmfront_init(void)
	438	{
	439	if (!xen_domain())
	440	return -ENODEV;
	441
51c71a3b KRW	442	if (!xen_has_pv_devices())
	443	return -ENODEV;
	444
e2683957 DDG	445	return xenbus_register_frontend(&tpmfront_driver);
	446	}
	447	module_init(xen_tpmfront_init);
	448
	449	static void __exit xen_tpmfront_exit(void)
	450	{
	451	xenbus_unregister_driver(&tpmfront_driver);
	452	}
	453	module_exit(xen_tpmfront_exit);
	454
	455	MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
	456	MODULE_DESCRIPTION("Xen vTPM Driver");
	457	MODULE_LICENSE("GPL");