linux/drivers/gpu/host1x/cdma.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Tegra host1x Command DMA
 *
 * Copyright (c) 2010-2013, NVIDIA Corporation.
 */


#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.
 */

/*
 * Typically the commands written into the push buffer are a pair of words. We
 * use slots to represent each of these pairs and to simplify things. Note the
 * strange number of slots allocated here. 512 slots will fit exactly within a
 * single memory page. We also need one additional word at the end of the push
 * buffer for the RESTART opcode that will instruct the CDMA to jump back to
 * the beginning of the push buffer. With 512 slots, this means that we'll use
 * 2 memory pages and waste 4092 bytes of the second page that will never be
 * used.
 */
#define HOST1X_PUSHBUFFER_SLOTS …

/*
 * Clean up push buffer resources
 */
static void host1x_pushbuffer_destroy(struct push_buffer *pb)
{ … }

/*
 * Init push buffer resources
 */
static int host1x_pushbuffer_init(struct push_buffer *pb)
{ … }

/*
 * 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)
{ … }

/*
 * 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)
{ … }

/*
 * Return the number of two word slots free in the push buffer
 */
static u32 host1x_pushbuffer_space(struct push_buffer *pb)
{ … }

/*
 * 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)
{ … }

/*
 * Sleep (if necessary) until the push buffer has enough free space.
 *
 * Must be called with the cdma lock held.
 */
static int host1x_cdma_wait_pushbuffer_space(struct host1x *host1x,
					     struct host1x_cdma *cdma,
					     unsigned int needed)
{ … }
/*
 * 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)
{ … }

/*
 * 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)
{ … }

/*
 * 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)
{ … }

void host1x_cdma_update_sync_queue(struct host1x_cdma *cdma,
				   struct device *dev)
{ … }

static void cdma_update_work(struct work_struct *work)
{ … }

/*
 * Create a cdma
 */
int host1x_cdma_init(struct host1x_cdma *cdma)
{ … }

/*
 * Destroy a cdma
 */
int host1x_cdma_deinit(struct host1x_cdma *cdma)
{ … }

/*
 * Begin a cdma submit
 */
int host1x_cdma_begin(struct host1x_cdma *cdma, struct host1x_job *job)
{ … }

/*
 * 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)
{ … }

/*
 * Push four words into two consecutive push buffer slots. Note that extra
 * care needs to be taken not to split the two slots across the end of the
 * push buffer. Otherwise the RESTART opcode at the end of the push buffer
 * that ensures processing will restart at the beginning will break up the
 * four words.
 *
 * Blocks as necessary if the push buffer is full.
 */
void host1x_cdma_push_wide(struct host1x_cdma *cdma, u32 op1, u32 op2,
			   u32 op3, u32 op4)
{ … }

/*
 * 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)
{ … }

/*
 * Update cdma state according to current sync point values
 */
void host1x_cdma_update(struct host1x_cdma *cdma)
{ … }