alistair23-linux/drivers/gpu/host1x/channel.c

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

#include <linux/slab.h>
#include <linux/module.h>

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

/* Constructor for the host1x device list */
int host1x_channel_list_init(struct host1x_channel_list *chlist,
			     unsigned int num_channels)
{
	chlist->channels = kcalloc(num_channels, sizeof(struct host1x_channel),
				   GFP_KERNEL);
	if (!chlist->channels)
		return -ENOMEM;

	chlist->allocated_channels =
		kcalloc(BITS_TO_LONGS(num_channels), sizeof(unsigned long),
			GFP_KERNEL);
	if (!chlist->allocated_channels) {
		kfree(chlist->channels);
		return -ENOMEM;
	}

	bitmap_zero(chlist->allocated_channels, num_channels);

	return 0;
}

void host1x_channel_list_free(struct host1x_channel_list *chlist)
{
	kfree(chlist->allocated_channels);
	kfree(chlist->channels);
}

int host1x_job_submit(struct host1x_job *job)
{
	struct host1x *host = dev_get_drvdata(job->channel->dev->parent);

	return host1x_hw_channel_submit(host, job);
}
EXPORT_SYMBOL(host1x_job_submit);

struct host1x_channel *host1x_channel_get(struct host1x_channel *channel)
{
	kref_get(&channel->refcount);

	return channel;
}
EXPORT_SYMBOL(host1x_channel_get);

/**
 * host1x_channel_get_index() - Attempt to get channel reference by index
 * @host: Host1x device object
 * @index: Index of channel
 *
 * If channel number @index is currently allocated, increase its refcount
 * and return a pointer to it. Otherwise, return NULL.
 */
struct host1x_channel *host1x_channel_get_index(struct host1x *host,
						unsigned int index)
{
	struct host1x_channel *ch = &host->channel_list.channels[index];

	if (!kref_get_unless_zero(&ch->refcount))
		return NULL;

	return ch;
}

static void release_channel(struct kref *kref)
{
	struct host1x_channel *channel =
		container_of(kref, struct host1x_channel, refcount);
	struct host1x *host = dev_get_drvdata(channel->dev->parent);
	struct host1x_channel_list *chlist = &host->channel_list;

	host1x_hw_cdma_stop(host, &channel->cdma);
	host1x_cdma_deinit(&channel->cdma);

	clear_bit(channel->id, chlist->allocated_channels);
}

void host1x_channel_put(struct host1x_channel *channel)
{
	kref_put(&channel->refcount, release_channel);
}
EXPORT_SYMBOL(host1x_channel_put);

static struct host1x_channel *acquire_unused_channel(struct host1x *host)
{
	struct host1x_channel_list *chlist = &host->channel_list;
	unsigned int max_channels = host->info->nb_channels;
	unsigned int index;

	index = find_first_zero_bit(chlist->allocated_channels, max_channels);
	if (index >= max_channels) {
		dev_err(host->dev, "failed to find free channel\n");
		return NULL;
	}

	chlist->channels[index].id = index;

	set_bit(index, chlist->allocated_channels);

	return &chlist->channels[index];
}

/**
 * host1x_channel_request() - Allocate a channel
 * @device: Host1x unit this channel will be used to send commands to
 *
 * Allocates a new host1x channel for @device. May return NULL if CDMA
 * initialization fails.
 */
struct host1x_channel *host1x_channel_request(struct device *dev)
{
	struct host1x *host = dev_get_drvdata(dev->parent);
	struct host1x_channel_list *chlist = &host->channel_list;
	struct host1x_channel *channel;
	int err;

	channel = acquire_unused_channel(host);
	if (!channel)
		return NULL;

	kref_init(&channel->refcount);
	mutex_init(&channel->submitlock);
	channel->dev = dev;

	err = host1x_hw_channel_init(host, channel, channel->id);
	if (err < 0)
		goto fail;

	err = host1x_cdma_init(&channel->cdma);
	if (err < 0)
		goto fail;

	return channel;

fail:
	clear_bit(channel->id, chlist->allocated_channels);

	dev_err(dev, "failed to initialize channel\n");

	return NULL;
}
EXPORT_SYMBOL(host1x_channel_request);