/*
 * Copyright IBM Corp. 2016
 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 *
 * Adjunct processor bus, queue related code.
 */

#define KMSG_COMPONENT "ap"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/init.h>
#include <linux/slab.h>
#include <asm/facility.h>

#include "ap_bus.h"
#include "ap_asm.h"

/**
 * ap_queue_enable_interruption(): Enable interruption on an AP queue.
 * @qid: The AP queue number
 * @ind: the notification indicator byte
 *
 * Enables interruption on AP queue via ap_aqic(). Based on the return
 * value it waits a while and tests the AP queue if interrupts
 * have been switched on using ap_test_queue().
 */
static int ap_queue_enable_interruption(struct ap_queue *aq, void *ind)
{
	struct ap_queue_status status;

	status = ap_aqic(aq->qid, ind);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
	case AP_RESPONSE_OTHERWISE_CHANGED:
		return 0;
	case AP_RESPONSE_Q_NOT_AVAIL:
	case AP_RESPONSE_DECONFIGURED:
	case AP_RESPONSE_CHECKSTOPPED:
	case AP_RESPONSE_INVALID_ADDRESS:
		pr_err("Registering adapter interrupts for AP device %02x.%04x failed\n",
		       AP_QID_CARD(aq->qid),
		       AP_QID_QUEUE(aq->qid));
		return -EOPNOTSUPP;
	case AP_RESPONSE_RESET_IN_PROGRESS:
	case AP_RESPONSE_BUSY:
	default:
		return -EBUSY;
	}
}

/**
 * __ap_send(): Send message to adjunct processor queue.
 * @qid: The AP queue number
 * @psmid: The program supplied message identifier
 * @msg: The message text
 * @length: The message length
 * @special: Special Bit
 *
 * Returns AP queue status structure.
 * Condition code 1 on NQAP can't happen because the L bit is 1.
 * Condition code 2 on NQAP also means the send is incomplete,
 * because a segment boundary was reached. The NQAP is repeated.
 */
static inline struct ap_queue_status
__ap_send(ap_qid_t qid, unsigned long long psmid, void *msg, size_t length,
	  unsigned int special)
{
	if (special == 1)
		qid |= 0x400000UL;
	return ap_nqap(qid, psmid, msg, length);
}

int ap_send(ap_qid_t qid, unsigned long long psmid, void *msg, size_t length)
{
	struct ap_queue_status status;

	status = __ap_send(qid, psmid, msg, length, 0);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		return 0;
	case AP_RESPONSE_Q_FULL:
	case AP_RESPONSE_RESET_IN_PROGRESS:
		return -EBUSY;
	case AP_RESPONSE_REQ_FAC_NOT_INST:
		return -EINVAL;
	default:	/* Device is gone. */
		return -ENODEV;
	}
}
EXPORT_SYMBOL(ap_send);

int ap_recv(ap_qid_t qid, unsigned long long *psmid, void *msg, size_t length)
{
	struct ap_queue_status status;

	if (msg == NULL)
		return -EINVAL;
	status = ap_dqap(qid, psmid, msg, length);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		return 0;
	case AP_RESPONSE_NO_PENDING_REPLY:
		if (status.queue_empty)
			return -ENOENT;
		return -EBUSY;
	case AP_RESPONSE_RESET_IN_PROGRESS:
		return -EBUSY;
	default:
		return -ENODEV;
	}
}
EXPORT_SYMBOL(ap_recv);

/* State machine definitions and helpers */

static enum ap_wait ap_sm_nop(struct ap_queue *aq)
{
	return AP_WAIT_NONE;
}

/**
 * ap_sm_recv(): Receive pending reply messages from an AP queue but do
 *	not change the state of the device.
 * @aq: pointer to the AP queue
 *
 * Returns AP_WAIT_NONE, AP_WAIT_AGAIN, or AP_WAIT_INTERRUPT
 */
static struct ap_queue_status ap_sm_recv(struct ap_queue *aq)
{
	struct ap_queue_status status;
	struct ap_message *ap_msg;

	status = ap_dqap(aq->qid, &aq->reply->psmid,
			 aq->reply->message, aq->reply->length);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		aq->queue_count--;
		if (aq->queue_count > 0)
			mod_timer(&aq->timeout,
				  jiffies + aq->request_timeout);
		list_for_each_entry(ap_msg, &aq->pendingq, list) {
			if (ap_msg->psmid != aq->reply->psmid)
				continue;
			list_del_init(&ap_msg->list);
			aq->pendingq_count--;
			ap_msg->receive(aq, ap_msg, aq->reply);
			break;
		}
	case AP_RESPONSE_NO_PENDING_REPLY:
		if (!status.queue_empty || aq->queue_count <= 0)
			break;
		/* The card shouldn't forget requests but who knows. */
		aq->queue_count = 0;
		list_splice_init(&aq->pendingq, &aq->requestq);
		aq->requestq_count += aq->pendingq_count;
		aq->pendingq_count = 0;
		break;
	default:
		break;
	}
	return status;
}

/**
 * ap_sm_read(): Receive pending reply messages from an AP queue.
 * @aq: pointer to the AP queue
 *
 * Returns AP_WAIT_NONE, AP_WAIT_AGAIN, or AP_WAIT_INTERRUPT
 */
static enum ap_wait ap_sm_read(struct ap_queue *aq)
{
	struct ap_queue_status status;

	if (!aq->reply)
		return AP_WAIT_NONE;
	status = ap_sm_recv(aq);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		if (aq->queue_count > 0) {
			aq->state = AP_STATE_WORKING;
			return AP_WAIT_AGAIN;
		}
		aq->state = AP_STATE_IDLE;
		return AP_WAIT_NONE;
	case AP_RESPONSE_NO_PENDING_REPLY:
		if (aq->queue_count > 0)
			return AP_WAIT_INTERRUPT;
		aq->state = AP_STATE_IDLE;
		return AP_WAIT_NONE;
	default:
		aq->state = AP_STATE_BORKED;
		return AP_WAIT_NONE;
	}
}

/**
 * ap_sm_suspend_read(): Receive pending reply messages from an AP queue
 * without changing the device state in between. In suspend mode we don't
 * allow sending new requests, therefore just fetch pending replies.
 * @aq: pointer to the AP queue
 *
 * Returns AP_WAIT_NONE or AP_WAIT_AGAIN
 */
static enum ap_wait ap_sm_suspend_read(struct ap_queue *aq)
{
	struct ap_queue_status status;

	if (!aq->reply)
		return AP_WAIT_NONE;
	status = ap_sm_recv(aq);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		if (aq->queue_count > 0)
			return AP_WAIT_AGAIN;
		/* fall through */
	default:
		return AP_WAIT_NONE;
	}
}

/**
 * ap_sm_write(): Send messages from the request queue to an AP queue.
 * @aq: pointer to the AP queue
 *
 * Returns AP_WAIT_NONE, AP_WAIT_AGAIN, or AP_WAIT_INTERRUPT
 */
static enum ap_wait ap_sm_write(struct ap_queue *aq)
{
	struct ap_queue_status status;
	struct ap_message *ap_msg;

	if (aq->requestq_count <= 0)
		return AP_WAIT_NONE;
	/* Start the next request on the queue. */
	ap_msg = list_entry(aq->requestq.next, struct ap_message, list);
	status = __ap_send(aq->qid, ap_msg->psmid,
			   ap_msg->message, ap_msg->length, ap_msg->special);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		aq->queue_count++;
		if (aq->queue_count == 1)
			mod_timer(&aq->timeout, jiffies + aq->request_timeout);
		list_move_tail(&ap_msg->list, &aq->pendingq);
		aq->requestq_count--;
		aq->pendingq_count++;
		if (aq->queue_count < aq->card->queue_depth) {
			aq->state = AP_STATE_WORKING;
			return AP_WAIT_AGAIN;
		}
		/* fall through */
	case AP_RESPONSE_Q_FULL:
		aq->state = AP_STATE_QUEUE_FULL;
		return AP_WAIT_INTERRUPT;
	case AP_RESPONSE_RESET_IN_PROGRESS:
		aq->state = AP_STATE_RESET_WAIT;
		return AP_WAIT_TIMEOUT;
	case AP_RESPONSE_MESSAGE_TOO_BIG:
	case AP_RESPONSE_REQ_FAC_NOT_INST:
		list_del_init(&ap_msg->list);
		aq->requestq_count--;
		ap_msg->rc = -EINVAL;
		ap_msg->receive(aq, ap_msg, NULL);
		return AP_WAIT_AGAIN;
	default:
		aq->state = AP_STATE_BORKED;
		return AP_WAIT_NONE;
	}
}

/**
 * ap_sm_read_write(): Send and receive messages to/from an AP queue.
 * @aq: pointer to the AP queue
 *
 * Returns AP_WAIT_NONE, AP_WAIT_AGAIN, or AP_WAIT_INTERRUPT
 */
static enum ap_wait ap_sm_read_write(struct ap_queue *aq)
{
	return min(ap_sm_read(aq), ap_sm_write(aq));
}

/**
 * ap_sm_reset(): Reset an AP queue.
 * @qid: The AP queue number
 *
 * Submit the Reset command to an AP queue.
 */
static enum ap_wait ap_sm_reset(struct ap_queue *aq)
{
	struct ap_queue_status status;

	status = ap_rapq(aq->qid);
	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
	case AP_RESPONSE_RESET_IN_PROGRESS:
		aq->state = AP_STATE_RESET_WAIT;
		aq->interrupt = AP_INTR_DISABLED;
		return AP_WAIT_TIMEOUT;
	case AP_RESPONSE_BUSY:
		return AP_WAIT_TIMEOUT;
	case AP_RESPONSE_Q_NOT_AVAIL:
	case AP_RESPONSE_DECONFIGURED:
	case AP_RESPONSE_CHECKSTOPPED:
	default:
		aq->state = AP_STATE_BORKED;
		return AP_WAIT_NONE;
	}
}

/**
 * ap_sm_reset_wait(): Test queue for completion of the reset operation
 * @aq: pointer to the AP queue
 *
 * Returns AP_POLL_IMMEDIATELY, AP_POLL_AFTER_TIMEROUT or 0.
 */
static enum ap_wait ap_sm_reset_wait(struct ap_queue *aq)
{
	struct ap_queue_status status;
	void *lsi_ptr;

	if (aq->queue_count > 0 && aq->reply)
		/* Try to read a completed message and get the status */
		status = ap_sm_recv(aq);
	else
		/* Get the status with TAPQ */
		status = ap_tapq(aq->qid, NULL);

	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		lsi_ptr = ap_airq_ptr();
		if (lsi_ptr && ap_queue_enable_interruption(aq, lsi_ptr) == 0)
			aq->state = AP_STATE_SETIRQ_WAIT;
		else
			aq->state = (aq->queue_count > 0) ?
				AP_STATE_WORKING : AP_STATE_IDLE;
		return AP_WAIT_AGAIN;
	case AP_RESPONSE_BUSY:
	case AP_RESPONSE_RESET_IN_PROGRESS:
		return AP_WAIT_TIMEOUT;
	case AP_RESPONSE_Q_NOT_AVAIL:
	case AP_RESPONSE_DECONFIGURED:
	case AP_RESPONSE_CHECKSTOPPED:
	default:
		aq->state = AP_STATE_BORKED;
		return AP_WAIT_NONE;
	}
}

/**
 * ap_sm_setirq_wait(): Test queue for completion of the irq enablement
 * @aq: pointer to the AP queue
 *
 * Returns AP_POLL_IMMEDIATELY, AP_POLL_AFTER_TIMEROUT or 0.
 */
static enum ap_wait ap_sm_setirq_wait(struct ap_queue *aq)
{
	struct ap_queue_status status;

	if (aq->queue_count > 0 && aq->reply)
		/* Try to read a completed message and get the status */
		status = ap_sm_recv(aq);
	else
		/* Get the status with TAPQ */
		status = ap_tapq(aq->qid, NULL);

	if (status.int_enabled == 1) {
		/* Irqs are now enabled */
		aq->interrupt = AP_INTR_ENABLED;
		aq->state = (aq->queue_count > 0) ?
			AP_STATE_WORKING : AP_STATE_IDLE;
	}

	switch (status.response_code) {
	case AP_RESPONSE_NORMAL:
		if (aq->queue_count > 0)
			return AP_WAIT_AGAIN;
		/* fallthrough */
	case AP_RESPONSE_NO_PENDING_REPLY:
		return AP_WAIT_TIMEOUT;
	default:
		aq->state = AP_STATE_BORKED;
		return AP_WAIT_NONE;
	}
}

/*
 * AP state machine jump table
 */
static ap_func_t *ap_jumptable[NR_AP_STATES][NR_AP_EVENTS] = {
	[AP_STATE_RESET_START] = {
		[AP_EVENT_POLL] = ap_sm_reset,
		[AP_EVENT_TIMEOUT] = ap_sm_nop,
	},
	[AP_STATE_RESET_WAIT] = {
		[AP_EVENT_POLL] = ap_sm_reset_wait,
		[AP_EVENT_TIMEOUT] = ap_sm_nop,
	},
	[AP_STATE_SETIRQ_WAIT] = {
		[AP_EVENT_POLL] = ap_sm_setirq_wait,
		[AP_EVENT_TIMEOUT] = ap_sm_nop,
	},
	[AP_STATE_IDLE] = {
		[AP_EVENT_POLL] = ap_sm_write,
		[AP_EVENT_TIMEOUT] = ap_sm_nop,
	},
	[AP_STATE_WORKING] = {
		[AP_EVENT_POLL] = ap_sm_read_write,
		[AP_EVENT_TIMEOUT] = ap_sm_reset,
	},
	[AP_STATE_QUEUE_FULL] = {
		[AP_EVENT_POLL] = ap_sm_read,
		[AP_EVENT_TIMEOUT] = ap_sm_reset,
	},
	[AP_STATE_SUSPEND_WAIT] = {
		[AP_EVENT_POLL] = ap_sm_suspend_read,
		[AP_EVENT_TIMEOUT] = ap_sm_nop,
	},
	[AP_STATE_BORKED] = {
		[AP_EVENT_POLL] = ap_sm_nop,
		[AP_EVENT_TIMEOUT] = ap_sm_nop,
	},
};

enum ap_wait ap_sm_event(struct ap_queue *aq, enum ap_event event)
{
	return ap_jumptable[aq->state][event](aq);
}

enum ap_wait ap_sm_event_loop(struct ap_queue *aq, enum ap_event event)
{
	enum ap_wait wait;

	while ((wait = ap_sm_event(aq, event)) == AP_WAIT_AGAIN)
		;
	return wait;
}

/*
 * Power management for queue devices
 */
void ap_queue_suspend(struct ap_device *ap_dev)
{
	struct ap_queue *aq = to_ap_queue(&ap_dev->device);

	/* Poll on the device until all requests are finished. */
	spin_lock_bh(&aq->lock);
	aq->state = AP_STATE_SUSPEND_WAIT;
	while (ap_sm_event(aq, AP_EVENT_POLL) != AP_WAIT_NONE)
		;
	aq->state = AP_STATE_BORKED;
	spin_unlock_bh(&aq->lock);
}
EXPORT_SYMBOL(ap_queue_suspend);

void ap_queue_resume(struct ap_device *ap_dev)
{
}
EXPORT_SYMBOL(ap_queue_resume);

/*
 * AP queue related attributes.
 */
static ssize_t ap_request_count_show(struct device *dev,
				     struct device_attribute *attr,
				     char *buf)
{
	struct ap_queue *aq = to_ap_queue(dev);
	unsigned int req_cnt;

	spin_lock_bh(&aq->lock);
	req_cnt = aq->total_request_count;
	spin_unlock_bh(&aq->lock);
	return snprintf(buf, PAGE_SIZE, "%d\n", req_cnt);
}

static DEVICE_ATTR(request_count, 0444, ap_request_count_show, NULL);

static ssize_t ap_requestq_count_show(struct device *dev,
				      struct device_attribute *attr, char *buf)
{
	struct ap_queue *aq = to_ap_queue(dev);
	unsigned int reqq_cnt = 0;

	spin_lock_bh(&aq->lock);
	reqq_cnt = aq->requestq_count;
	spin_unlock_bh(&aq->lock);
	return snprintf(buf, PAGE_SIZE, "%d\n", reqq_cnt);
}

static DEVICE_ATTR(requestq_count, 0444, ap_requestq_count_show, NULL);

static ssize_t ap_pendingq_count_show(struct device *dev,
				      struct device_attribute *attr, char *buf)
{
	struct ap_queue *aq = to_ap_queue(dev);
	unsigned int penq_cnt = 0;

	spin_lock_bh(&aq->lock);
	penq_cnt = aq->pendingq_count;
	spin_unlock_bh(&aq->lock);
	return snprintf(buf, PAGE_SIZE, "%d\n", penq_cnt);
}

static DEVICE_ATTR(pendingq_count, 0444, ap_pendingq_count_show, NULL);

static ssize_t ap_reset_show(struct device *dev,
				      struct device_attribute *attr, char *buf)
{
	struct ap_queue *aq = to_ap_queue(dev);
	int rc = 0;

	spin_lock_bh(&aq->lock);
	switch (aq->state) {
	case AP_STATE_RESET_START:
	case AP_STATE_RESET_WAIT:
		rc = snprintf(buf, PAGE_SIZE, "Reset in progress.\n");
		break;
	case AP_STATE_WORKING:
	case AP_STATE_QUEUE_FULL:
		rc = snprintf(buf, PAGE_SIZE, "Reset Timer armed.\n");
		break;
	default:
		rc = snprintf(buf, PAGE_SIZE, "No Reset Timer set.\n");
	}
	spin_unlock_bh(&aq->lock);
	return rc;
}

static DEVICE_ATTR(reset, 0444, ap_reset_show, NULL);

static ssize_t ap_interrupt_show(struct device *dev,
				 struct device_attribute *attr, char *buf)
{
	struct ap_queue *aq = to_ap_queue(dev);
	int rc = 0;

	spin_lock_bh(&aq->lock);
	if (aq->state == AP_STATE_SETIRQ_WAIT)
		rc = snprintf(buf, PAGE_SIZE, "Enable Interrupt pending.\n");
	else if (aq->interrupt == AP_INTR_ENABLED)
		rc = snprintf(buf, PAGE_SIZE, "Interrupts enabled.\n");
	else
		rc = snprintf(buf, PAGE_SIZE, "Interrupts disabled.\n");
	spin_unlock_bh(&aq->lock);
	return rc;
}

static DEVICE_ATTR(interrupt, 0444, ap_interrupt_show, NULL);

static struct attribute *ap_queue_dev_attrs[] = {
	&dev_attr_request_count.attr,
	&dev_attr_requestq_count.attr,
	&dev_attr_pendingq_count.attr,
	&dev_attr_reset.attr,
	&dev_attr_interrupt.attr,
	NULL
};

static struct attribute_group ap_queue_dev_attr_group = {
	.attrs = ap_queue_dev_attrs
};

static const struct attribute_group *ap_queue_dev_attr_groups[] = {
	&ap_queue_dev_attr_group,
	NULL
};

struct device_type ap_queue_type = {
	.name = "ap_queue",
	.groups = ap_queue_dev_attr_groups,
};

static void ap_queue_device_release(struct device *dev)
{
	kfree(to_ap_queue(dev));
}

struct ap_queue *ap_queue_create(ap_qid_t qid, int device_type)
{
	struct ap_queue *aq;

	aq = kzalloc(sizeof(*aq), GFP_KERNEL);
	if (!aq)
		return NULL;
	aq->ap_dev.device.release = ap_queue_device_release;
	aq->ap_dev.device.type = &ap_queue_type;
	aq->ap_dev.device_type = device_type;
	/* CEX6 toleration: map to CEX5 */
	if (device_type == AP_DEVICE_TYPE_CEX6)
		aq->ap_dev.device_type = AP_DEVICE_TYPE_CEX5;
	aq->qid = qid;
	aq->state = AP_STATE_RESET_START;
	aq->interrupt = AP_INTR_DISABLED;
	spin_lock_init(&aq->lock);
	INIT_LIST_HEAD(&aq->pendingq);
	INIT_LIST_HEAD(&aq->requestq);
	setup_timer(&aq->timeout, ap_request_timeout, (unsigned long) aq);

	return aq;
}

void ap_queue_init_reply(struct ap_queue *aq, struct ap_message *reply)
{
	aq->reply = reply;

	spin_lock_bh(&aq->lock);
	ap_wait(ap_sm_event(aq, AP_EVENT_POLL));
	spin_unlock_bh(&aq->lock);
}
EXPORT_SYMBOL(ap_queue_init_reply);

/**
 * ap_queue_message(): Queue a request to an AP device.
 * @aq: The AP device to queue the message to
 * @ap_msg: The message that is to be added
 */
void ap_queue_message(struct ap_queue *aq, struct ap_message *ap_msg)
{
	/* For asynchronous message handling a valid receive-callback
	 * is required.
	 */
	BUG_ON(!ap_msg->receive);

	spin_lock_bh(&aq->lock);
	/* Queue the message. */
	list_add_tail(&ap_msg->list, &aq->requestq);
	aq->requestq_count++;
	aq->total_request_count++;
	atomic_inc(&aq->card->total_request_count);
	/* Send/receive as many request from the queue as possible. */
	ap_wait(ap_sm_event_loop(aq, AP_EVENT_POLL));
	spin_unlock_bh(&aq->lock);
}
EXPORT_SYMBOL(ap_queue_message);

/**
 * ap_cancel_message(): Cancel a crypto request.
 * @aq: The AP device that has the message queued
 * @ap_msg: The message that is to be removed
 *
 * Cancel a crypto request. This is done by removing the request
 * from the device pending or request queue. Note that the
 * request stays on the AP queue. When it finishes the message
 * reply will be discarded because the psmid can't be found.
 */
void ap_cancel_message(struct ap_queue *aq, struct ap_message *ap_msg)
{
	struct ap_message *tmp;

	spin_lock_bh(&aq->lock);
	if (!list_empty(&ap_msg->list)) {
		list_for_each_entry(tmp, &aq->pendingq, list)
			if (tmp->psmid == ap_msg->psmid) {
				aq->pendingq_count--;
				goto found;
			}
		aq->requestq_count--;
found:
		list_del_init(&ap_msg->list);
	}
	spin_unlock_bh(&aq->lock);
}
EXPORT_SYMBOL(ap_cancel_message);

/**
 * __ap_flush_queue(): Flush requests.
 * @aq: Pointer to the AP queue
 *
 * Flush all requests from the request/pending queue of an AP device.
 */
static void __ap_flush_queue(struct ap_queue *aq)
{
	struct ap_message *ap_msg, *next;

	list_for_each_entry_safe(ap_msg, next, &aq->pendingq, list) {
		list_del_init(&ap_msg->list);
		aq->pendingq_count--;
		ap_msg->rc = -EAGAIN;
		ap_msg->receive(aq, ap_msg, NULL);
	}
	list_for_each_entry_safe(ap_msg, next, &aq->requestq, list) {
		list_del_init(&ap_msg->list);
		aq->requestq_count--;
		ap_msg->rc = -EAGAIN;
		ap_msg->receive(aq, ap_msg, NULL);
	}
}

void ap_flush_queue(struct ap_queue *aq)
{
	spin_lock_bh(&aq->lock);
	__ap_flush_queue(aq);
	spin_unlock_bh(&aq->lock);
}
EXPORT_SYMBOL(ap_flush_queue);

void ap_queue_remove(struct ap_queue *aq)
{
	ap_flush_queue(aq);
	del_timer_sync(&aq->timeout);
}
EXPORT_SYMBOL(ap_queue_remove);