/* Copyright 2014-2015 IBM Corp.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *	http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.
 * See the License for the specific language governing permissions and
 * imitations under the License.
 */

#include <skiboot.h>
#include <opal.h>
#include <lock.h>
#include <xscom.h>
#include <chip.h>
#include <opal-api.h>
#include <opal-msg.h>
#include <fsp.h>

enum events {
	EVENT_ATTN	= 1 << 0,
	EVENT_OCC_ERROR	= 1 << 1,
	EVENT_OCC_RESET	= 1 << 2,
};

static uint8_t events[MAX_CHIPS];
static uint64_t ipoll_status[MAX_CHIPS];
static struct opal_prd_msg prd_msg;
static bool prd_msg_inuse, prd_active;

/* Locking:
 *
 * The events lock serialises access to the events, ipoll_status,
 * prd_msg_inuse, and prd_active variables.
 *
 * The ipoll_lock protects against concurrent updates to the ipoll registers.
 *
 * The ipoll_lock may be acquired with events_lock held. This order must
 * be preserved.
 */
static struct lock events_lock = LOCK_UNLOCKED;
static struct lock ipoll_lock = LOCK_UNLOCKED;

/* PRD registers */
#define PRD_IPOLL_REG_MASK	0x01020013
#define PRD_IPOLL_REG_STATUS	0x01020014
#define PRD_IPOLL_XSTOP		PPC_BIT(0) /* Xstop for host/core/millicode */
#define PRD_IPOLL_RECOV		PPC_BIT(1) /* Recoverable */
#define PRD_IPOLL_SPEC_ATTN	PPC_BIT(2) /* Special attention */
#define PRD_IPOLL_HOST_ATTN	PPC_BIT(3) /* Host attention */
#define PRD_IPOLL_MASK		PPC_BITMASK(0, 3)

static int queue_prd_msg_hbrt(struct opal_prd_msg *msg,
		void (*consumed)(void *data))
{
	uint64_t *buf;

	BUILD_ASSERT(sizeof(*msg) / sizeof(uint64_t) == 4);

	buf = (uint64_t *)msg;

	return _opal_queue_msg(OPAL_MSG_PRD, msg, consumed, 4, buf);
}

static int queue_prd_msg_nop(struct opal_prd_msg *msg,
		void (*consumed)(void *data))
{
	(void)msg;
	(void)consumed;
	return OPAL_UNSUPPORTED;
}

static int (*queue_prd_msg)(struct opal_prd_msg *msg,
		void (*consumed)(void *data)) = queue_prd_msg_nop;

static void send_pending_events(void);

static void prd_msg_consumed(void *data)
{
	struct opal_prd_msg *msg = data;
	uint32_t proc;
	uint8_t event = 0;

	lock(&events_lock);
	switch (msg->type) {
	case OPAL_PRD_MSG_TYPE_ATTN:
		proc = msg->attn.proc;

		/* If other ipoll events have been received in the time
		 * between prd_msg creation and consumption, we'll need to
		 * raise a separate ATTN message for those. So, we only
		 * clear the event if we don't have any further ipoll_status
		 * bits.
		 */
		ipoll_status[proc] &= ~msg->attn.ipoll_status;
		if (!ipoll_status[proc])
			event = EVENT_ATTN;

		break;
	case OPAL_PRD_MSG_TYPE_OCC_ERROR:
		proc = msg->occ_error.chip;
		event = EVENT_OCC_ERROR;
		break;
	case OPAL_PRD_MSG_TYPE_OCC_RESET:
		proc = msg->occ_reset.chip;
		event = EVENT_OCC_RESET;
		break;
	default:
		return;
	}

	events[proc] &= ~event;
	prd_msg_inuse = false;
	send_pending_events();
	unlock(&events_lock);
}

static int populate_ipoll_msg(struct opal_prd_msg *msg, uint32_t proc)
{
	uint64_t ipoll_mask;
	int rc;

	lock(&ipoll_lock);
	rc = xscom_read(proc, PRD_IPOLL_REG_MASK, &ipoll_mask);
	unlock(&ipoll_lock);

	if (rc) {
		prlog(PR_ERR, "PRD: Unable to read ipoll status (chip %d)!\n",
				proc);
		return -1;
	}

	msg->attn.proc = proc;
	msg->attn.ipoll_status = ipoll_status[proc];
	msg->attn.ipoll_mask = ipoll_mask;
	return 0;
}

static void send_pending_events(void)
{
	struct proc_chip *chip;
	uint32_t proc;
	uint8_t event;

	assert(!prd_msg_inuse);

	if (!prd_active)
		return;

	event = 0;

	for_each_chip(chip) {
		proc = chip->id;
		if (events[proc]) {
			event = events[proc];
			break;
		}
	}

	if (!event)
		return;

	prd_msg_inuse = true;
	prd_msg.token = 0;

	if (event & EVENT_ATTN) {
		prd_msg.type = OPAL_PRD_MSG_TYPE_ATTN;
		populate_ipoll_msg(&prd_msg, proc);
		event = EVENT_ATTN;

	} else if (event & EVENT_OCC_ERROR) {
		prd_msg.type = OPAL_PRD_MSG_TYPE_OCC_ERROR;
		prd_msg.occ_error.chip = proc;
		event = EVENT_OCC_ERROR;

	} else if (event & EVENT_OCC_RESET) {
		prd_msg.type = OPAL_PRD_MSG_TYPE_OCC_RESET;
		prd_msg.occ_reset.chip = proc;
		event = EVENT_OCC_RESET;

	}

	queue_prd_msg(&prd_msg, prd_msg_consumed);
}

static void __prd_event(uint32_t proc, uint8_t event)
{
	events[proc] |= event;
	if (!prd_msg_inuse)
		send_pending_events();
}

static void prd_event(uint32_t proc, uint8_t event)
{
	lock(&events_lock);
	__prd_event(proc, event);
	unlock(&events_lock);
}

static int __ipoll_update_mask(uint32_t proc, bool set, uint64_t bits)
{
	uint64_t mask;
	int rc;

	rc = xscom_read(proc, PRD_IPOLL_REG_MASK, &mask);
	if (rc)
		return rc;

	if (set)
		mask |= bits;
	else
		mask &= ~bits;

	return xscom_write(proc, PRD_IPOLL_REG_MASK, mask);
}

static int ipoll_record_and_mask_pending(uint32_t proc)
{
	uint64_t status;
	int rc;

	lock(&ipoll_lock);
	rc = xscom_read(proc, PRD_IPOLL_REG_STATUS, &status);
	if (!rc)
		__ipoll_update_mask(proc, true, status);
	unlock(&ipoll_lock);

	if (!rc)
		ipoll_status[proc] |= (status & PRD_IPOLL_MASK);

	return rc;
}

/* Entry point for interrupts */
void prd_psi_interrupt(uint32_t proc)
{
	int rc;

	lock(&events_lock);

	rc = ipoll_record_and_mask_pending(proc);
	if (rc)
		prlog(PR_ERR, "PRD: Failed to update IPOLL mask\n");

	__prd_event(proc, EVENT_ATTN);

	unlock(&events_lock);
}

void prd_tmgt_interrupt(uint32_t proc)
{
	prd_event(proc, EVENT_OCC_ERROR);
}

void prd_occ_reset(uint32_t proc)
{
	prd_event(proc, EVENT_OCC_RESET);
}

/* incoming message handlers */
static int prd_msg_handle_attn_ack(struct opal_prd_msg *msg)
{
	int rc;

	lock(&ipoll_lock);
	rc = __ipoll_update_mask(msg->attn_ack.proc, false,
			msg->attn_ack.ipoll_ack & PRD_IPOLL_MASK);
	unlock(&ipoll_lock);

	if (rc)
		prlog(PR_ERR, "PRD: Unable to unmask ipoll!\n");

	return rc;
}

static int prd_msg_handle_init(struct opal_prd_msg *msg)
{
	struct proc_chip *chip;

	lock(&ipoll_lock);
	for_each_chip(chip) {
		__ipoll_update_mask(chip->id, false, msg->init.ipoll);
	}
	unlock(&ipoll_lock);

	/* we're transitioning from inactive to active; send any pending tmgt
	 * interrupts */
	lock(&events_lock);
	prd_active = true;
	if (!prd_msg_inuse)
		send_pending_events();
	unlock(&events_lock);

	return OPAL_SUCCESS;
}

static int prd_msg_handle_fini(void)
{
	struct proc_chip *chip;

	lock(&events_lock);
	prd_active = false;
	unlock(&events_lock);

	lock(&ipoll_lock);
	for_each_chip(chip) {
		__ipoll_update_mask(chip->id, true, -1ul);
	}
	unlock(&ipoll_lock);

	return OPAL_SUCCESS;
}

/* Entry from the host above */
static int64_t opal_prd_msg(struct opal_prd_msg *msg)
{
	int rc;

	switch (msg->type) {
	case OPAL_PRD_MSG_TYPE_INIT:
		rc = prd_msg_handle_init(msg);
		break;
	case OPAL_PRD_MSG_TYPE_FINI:
		rc = prd_msg_handle_fini();
		break;
	case OPAL_PRD_MSG_TYPE_ATTN_ACK:
		rc = prd_msg_handle_attn_ack(msg);
		break;
	default:
		rc = OPAL_UNSUPPORTED;
	}

	return rc;
}

void prd_init(void)
{
	struct proc_chip *chip;

	/* mask everything */
	lock(&ipoll_lock);
	for_each_chip(chip) {
		__ipoll_update_mask(chip->id, true, -1ul);
	}
	unlock(&ipoll_lock);

	if (fsp_present()) {
		/* todo: FSP implementation */
		queue_prd_msg = queue_prd_msg_nop;
	} else {
		queue_prd_msg = queue_prd_msg_hbrt;
		opal_register(OPAL_PRD_MSG, opal_prd_msg, 1);
	}
}