/*
 * Tegra host1x Command DMA
 *
 * Copyright (c) 2010-2013, NVIDIA Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */


#include <asm/cacheflush.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/host1x.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kfifo.h>
#include <linux/slab.h>
#include <trace/events/host1x.h>

#include "cdma.h"
#include "channel.h"
#include "dev.h"
#include "debug.h"
#include "job.h"

/*
 * push_buffer
 *
 * The push buffer is a circular array of words to be fetched by command DMA.
 * Note that it works slightly differently to the sync queue; fence == pos
 * means that the push buffer is full, not empty.
 */

#define HOST1X_PUSHBUFFER_SLOTS	512

/*
 * Clean up push buffer resources
 */
static void host1x_pushbuffer_destroy(struct push_buffer *pb)
{
	struct host1x_cdma *cdma = pb_to_cdma(pb);
	struct host1x *host1x = cdma_to_host1x(cdma);

	if (pb->phys != 0)
		dma_free_writecombine(host1x->dev, pb->size_bytes + 4,
				      pb->mapped, pb->phys);

	pb->mapped = NULL;
	pb->phys = 0;
}

/*
 * Init push buffer resources
 */
static int host1x_pushbuffer_init(struct push_buffer *pb)
{
	struct host1x_cdma *cdma = pb_to_cdma(pb);
	struct host1x *host1x = cdma_to_host1x(cdma);

	pb->mapped = NULL;
	pb->phys = 0;
	pb->size_bytes = HOST1X_PUSHBUFFER_SLOTS * 8;

	/* initialize buffer pointers */
	pb->fence = pb->size_bytes - 8;
	pb->pos = 0;

	/* allocate and map pushbuffer memory */
	pb->mapped = dma_alloc_writecombine(host1x->dev, pb->size_bytes + 4,
					    &pb->phys, GFP_KERNEL);
	if (!pb->mapped)
		goto fail;

	host1x_hw_pushbuffer_init(host1x, pb);

	return 0;

fail:
	host1x_pushbuffer_destroy(pb);
	return -ENOMEM;
}

/*
 * Push two words to the push buffer
 * Caller must ensure push buffer is not full
 */
static void host1x_pushbuffer_push(struct push_buffer *pb, u32 op1, u32 op2)
{
	u32 pos = pb->pos;
	u32 *p = (u32 *)((u32)pb->mapped + pos);
	WARN_ON(pos == pb->fence);
	*(p++) = op1;
	*(p++) = op2;
	pb->pos = (pos + 8) & (pb->size_bytes - 1);
}

/*
 * Pop a number of two word slots from the push buffer
 * Caller must ensure push buffer is not empty
 */
static void host1x_pushbuffer_pop(struct push_buffer *pb, unsigned int slots)
{
	/* Advance the next write position */
	pb->fence = (pb->fence + slots * 8) & (pb->size_bytes - 1);
}

/*
 * Return the number of two word slots free in the push buffer
 */
static u32 host1x_pushbuffer_space(struct push_buffer *pb)
{
	return ((pb->fence - pb->pos) & (pb->size_bytes - 1)) / 8;
}

/*
 * Sleep (if necessary) until the requested event happens
 *   - CDMA_EVENT_SYNC_QUEUE_EMPTY : sync queue is completely empty.
 *     - Returns 1
 *   - CDMA_EVENT_PUSH_BUFFER_SPACE : there is space in the push buffer
 *     - Return the amount of space (> 0)
 * Must be called with the cdma lock held.
 */
unsigned int host1x_cdma_wait_locked(struct host1x_cdma *cdma,
				     enum cdma_event event)
{
	for (;;) {
		unsigned int space;

		if (event == CDMA_EVENT_SYNC_QUEUE_EMPTY)
			space = list_empty(&cdma->sync_queue) ? 1 : 0;
		else if (event == CDMA_EVENT_PUSH_BUFFER_SPACE) {
			struct push_buffer *pb = &cdma->push_buffer;
			space = host1x_pushbuffer_space(pb);
		} else {
			WARN_ON(1);
			return -EINVAL;
		}

		if (space)
			return space;

		trace_host1x_wait_cdma(dev_name(cdma_to_channel(cdma)->dev),
				       event);

		/* If somebody has managed to already start waiting, yield */
		if (cdma->event != CDMA_EVENT_NONE) {
			mutex_unlock(&cdma->lock);
			schedule();
			mutex_lock(&cdma->lock);
			continue;
		}
		cdma->event = event;

		mutex_unlock(&cdma->lock);
		down(&cdma->sem);
		mutex_lock(&cdma->lock);
	}
	return 0;
}

/*
 * Start timer that tracks the time spent by the job.
 * Must be called with the cdma lock held.
 */
static void cdma_start_timer_locked(struct host1x_cdma *cdma,
				    struct host1x_job *job)
{
	struct host1x *host = cdma_to_host1x(cdma);

	if (cdma->timeout.client) {
		/* timer already started */
		return;
	}

	cdma->timeout.client = job->client;
	cdma->timeout.syncpt = host1x_syncpt_get(host, job->syncpt_id);
	cdma->timeout.syncpt_val = job->syncpt_end;
	cdma->timeout.start_ktime = ktime_get();

	schedule_delayed_work(&cdma->timeout.wq,
			      msecs_to_jiffies(job->timeout));
}

/*
 * Stop timer when a buffer submission completes.
 * Must be called with the cdma lock held.
 */
static void stop_cdma_timer_locked(struct host1x_cdma *cdma)
{
	cancel_delayed_work(&cdma->timeout.wq);
	cdma->timeout.client = 0;
}

/*
 * For all sync queue entries that have already finished according to the
 * current sync point registers:
 *  - unpin & unref their mems
 *  - pop their push buffer slots
 *  - remove them from the sync queue
 * This is normally called from the host code's worker thread, but can be
 * called manually if necessary.
 * Must be called with the cdma lock held.
 */
static void update_cdma_locked(struct host1x_cdma *cdma)
{
	bool signal = false;
	struct host1x *host1x = cdma_to_host1x(cdma);
	struct host1x_job *job, *n;

	/* If CDMA is stopped, queue is cleared and we can return */
	if (!cdma->running)
		return;

	/*
	 * Walk the sync queue, reading the sync point registers as necessary,
	 * to consume as many sync queue entries as possible without blocking
	 */
	list_for_each_entry_safe(job, n, &cdma->sync_queue, list) {
		struct host1x_syncpt *sp =
			host1x_syncpt_get(host1x, job->syncpt_id);

		/* Check whether this syncpt has completed, and bail if not */
		if (!host1x_syncpt_is_expired(sp, job->syncpt_end)) {
			/* Start timer on next pending syncpt */
			if (job->timeout)
				cdma_start_timer_locked(cdma, job);
			break;
		}

		/* Cancel timeout, when a buffer completes */
		if (cdma->timeout.client)
			stop_cdma_timer_locked(cdma);

		/* Unpin the memory */
		host1x_job_unpin(job);

		/* Pop push buffer slots */
		if (job->num_slots) {
			struct push_buffer *pb = &cdma->push_buffer;
			host1x_pushbuffer_pop(pb, job->num_slots);
			if (cdma->event == CDMA_EVENT_PUSH_BUFFER_SPACE)
				signal = true;
		}

		list_del(&job->list);
		host1x_job_put(job);
	}

	if (cdma->event == CDMA_EVENT_SYNC_QUEUE_EMPTY &&
	    list_empty(&cdma->sync_queue))
		signal = true;

	if (signal) {
		cdma->event = CDMA_EVENT_NONE;
		up(&cdma->sem);
	}
}

void host1x_cdma_update_sync_queue(struct host1x_cdma *cdma,
				   struct device *dev)
{
	u32 restart_addr;
	u32 syncpt_incrs;
	struct host1x_job *job = NULL;
	u32 syncpt_val;
	struct host1x *host1x = cdma_to_host1x(cdma);

	syncpt_val = host1x_syncpt_load(cdma->timeout.syncpt);

	dev_dbg(dev, "%s: starting cleanup (thresh %d)\n",
		__func__, syncpt_val);

	/*
	 * Move the sync_queue read pointer to the first entry that hasn't
	 * completed based on the current HW syncpt value. It's likely there
	 * won't be any (i.e. we're still at the head), but covers the case
	 * where a syncpt incr happens just prior/during the teardown.
	 */

	dev_dbg(dev, "%s: skip completed buffers still in sync_queue\n",
		__func__);

	list_for_each_entry(job, &cdma->sync_queue, list) {
		if (syncpt_val < job->syncpt_end)
			break;

		host1x_job_dump(dev, job);
	}

	/*
	 * Walk the sync_queue, first incrementing with the CPU syncpts that
	 * are partially executed (the first buffer) or fully skipped while
	 * still in the current context (slots are also NOP-ed).
	 *
	 * At the point contexts are interleaved, syncpt increments must be
	 * done inline with the pushbuffer from a GATHER buffer to maintain
	 * the order (slots are modified to be a GATHER of syncpt incrs).
	 *
	 * Note: save in restart_addr the location where the timed out buffer
	 * started in the PB, so we can start the refetch from there (with the
	 * modified NOP-ed PB slots). This lets things appear to have completed
	 * properly for this buffer and resources are freed.
	 */

	dev_dbg(dev, "%s: perform CPU incr on pending same ctx buffers\n",
		__func__);

	if (!list_empty(&cdma->sync_queue))
		restart_addr = job->first_get;
	else
		restart_addr = cdma->last_pos;

	/* do CPU increments as long as this context continues */
	list_for_each_entry_from(job, &cdma->sync_queue, list) {
		/* different context, gets us out of this loop */
		if (job->client != cdma->timeout.client)
			break;

		/* won't need a timeout when replayed */
		job->timeout = 0;

		syncpt_incrs = job->syncpt_end - syncpt_val;
		dev_dbg(dev, "%s: CPU incr (%d)\n", __func__, syncpt_incrs);

		host1x_job_dump(dev, job);

		/* safe to use CPU to incr syncpts */
		host1x_hw_cdma_timeout_cpu_incr(host1x, cdma, job->first_get,
						syncpt_incrs, job->syncpt_end,
						job->num_slots);

		syncpt_val += syncpt_incrs;
	}

	/* The following sumbits from the same client may be dependent on the
	 * failed submit and therefore they may fail. Force a small timeout
	 * to make the queue cleanup faster */

	list_for_each_entry_from(job, &cdma->sync_queue, list)
		if (job->client == cdma->timeout.client)
			job->timeout = min_t(unsigned int, job->timeout, 500);

	dev_dbg(dev, "%s: finished sync_queue modification\n", __func__);

	/* roll back DMAGET and start up channel again */
	host1x_hw_cdma_resume(host1x, cdma, restart_addr);
}

/*
 * Create a cdma
 */
int host1x_cdma_init(struct host1x_cdma *cdma)
{
	int err;

	mutex_init(&cdma->lock);
	sema_init(&cdma->sem, 0);

	INIT_LIST_HEAD(&cdma->sync_queue);

	cdma->event = CDMA_EVENT_NONE;
	cdma->running = false;
	cdma->torndown = false;

	err = host1x_pushbuffer_init(&cdma->push_buffer);
	if (err)
		return err;
	return 0;
}

/*
 * Destroy a cdma
 */
int host1x_cdma_deinit(struct host1x_cdma *cdma)
{
	struct push_buffer *pb = &cdma->push_buffer;
	struct host1x *host1x = cdma_to_host1x(cdma);

	if (cdma->running) {
		pr_warn("%s: CDMA still running\n", __func__);
		return -EBUSY;
	}

	host1x_pushbuffer_destroy(pb);
	host1x_hw_cdma_timeout_destroy(host1x, cdma);

	return 0;
}

/*
 * Begin a cdma submit
 */
int host1x_cdma_begin(struct host1x_cdma *cdma, struct host1x_job *job)
{
	struct host1x *host1x = cdma_to_host1x(cdma);

	mutex_lock(&cdma->lock);

	if (job->timeout) {
		/* init state on first submit with timeout value */
		if (!cdma->timeout.initialized) {
			int err;
			err = host1x_hw_cdma_timeout_init(host1x, cdma,
							  job->syncpt_id);
			if (err) {
				mutex_unlock(&cdma->lock);
				return err;
			}
		}
	}
	if (!cdma->running)
		host1x_hw_cdma_start(host1x, cdma);

	cdma->slots_free = 0;
	cdma->slots_used = 0;
	cdma->first_get = cdma->push_buffer.pos;

	trace_host1x_cdma_begin(dev_name(job->channel->dev));
	return 0;
}

/*
 * Push two words into a push buffer slot
 * Blocks as necessary if the push buffer is full.
 */
void host1x_cdma_push(struct host1x_cdma *cdma, u32 op1, u32 op2)
{
	struct host1x *host1x = cdma_to_host1x(cdma);
	struct push_buffer *pb = &cdma->push_buffer;
	u32 slots_free = cdma->slots_free;

	if (host1x_debug_trace_cmdbuf)
		trace_host1x_cdma_push(dev_name(cdma_to_channel(cdma)->dev),
				       op1, op2);

	if (slots_free == 0) {
		host1x_hw_cdma_flush(host1x, cdma);
		slots_free = host1x_cdma_wait_locked(cdma,
						CDMA_EVENT_PUSH_BUFFER_SPACE);
	}
	cdma->slots_free = slots_free - 1;
	cdma->slots_used++;
	host1x_pushbuffer_push(pb, op1, op2);
}

/*
 * End a cdma submit
 * Kick off DMA, add job to the sync queue, and a number of slots to be freed
 * from the pushbuffer. The handles for a submit must all be pinned at the same
 * time, but they can be unpinned in smaller chunks.
 */
void host1x_cdma_end(struct host1x_cdma *cdma,
		     struct host1x_job *job)
{
	struct host1x *host1x = cdma_to_host1x(cdma);
	bool idle = list_empty(&cdma->sync_queue);

	host1x_hw_cdma_flush(host1x, cdma);

	job->first_get = cdma->first_get;
	job->num_slots = cdma->slots_used;
	host1x_job_get(job);
	list_add_tail(&job->list, &cdma->sync_queue);

	/* start timer on idle -> active transitions */
	if (job->timeout && idle)
		cdma_start_timer_locked(cdma, job);

	trace_host1x_cdma_end(dev_name(job->channel->dev));
	mutex_unlock(&cdma->lock);
}

/*
 * Update cdma state according to current sync point values
 */
void host1x_cdma_update(struct host1x_cdma *cdma)
{
	mutex_lock(&cdma->lock);
	update_cdma_locked(cdma);
	mutex_unlock(&cdma->lock);
}