drivers/dma/idxd/submit.c

// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2019 Intel Corporation. All rights rsvd. */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <uapi/linux/idxd.h>
#include "idxd.h"
#include "registers.h"

static struct idxd_desc *__get_desc(struct idxd_wq *wq, int idx, int cpu)
{
	struct idxd_desc *desc;

	desc = wq->descs[idx];
	memset(desc->hw, 0, sizeof(struct dsa_hw_desc));
	memset(desc->completion, 0, sizeof(struct dsa_completion_record));
	desc->cpu = cpu;
	return desc;
}

struct idxd_desc *idxd_alloc_desc(struct idxd_wq *wq, enum idxd_op_type optype)
{
	int cpu, idx;
	struct idxd_device *idxd = wq->idxd;
	DEFINE_SBQ_WAIT(wait);
	struct sbq_wait_state *ws;
	struct sbitmap_queue *sbq;

	if (idxd->state != IDXD_DEV_ENABLED)
		return ERR_PTR(-EIO);

	sbq = &wq->sbq;
	idx = sbitmap_queue_get(sbq, &cpu);
	if (idx < 0) {
		if (optype == IDXD_OP_NONBLOCK)
			return ERR_PTR(-EAGAIN);
	} else {
		return __get_desc(wq, idx, cpu);
	}

	ws = &sbq->ws[0];
	for (;;) {
		sbitmap_prepare_to_wait(sbq, ws, &wait, TASK_INTERRUPTIBLE);
		if (signal_pending_state(TASK_INTERRUPTIBLE, current))
			break;
		idx = sbitmap_queue_get(sbq, &cpu);
		if (idx >= 0)
			break;
		schedule();
	}

	sbitmap_finish_wait(sbq, ws, &wait);
	if (idx < 0)
		return ERR_PTR(-EAGAIN);

	return __get_desc(wq, idx, cpu);
}

void idxd_free_desc(struct idxd_wq *wq, struct idxd_desc *desc)
{
	int cpu = desc->cpu;

	desc->cpu = -1;
	sbitmap_queue_clear(&wq->sbq, desc->id, cpu);
}

int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
{
	struct idxd_device *idxd = wq->idxd;
	int vec = desc->hw->int_handle;
	void __iomem *portal;

	if (idxd->state != IDXD_DEV_ENABLED)
		return -EIO;

	portal = wq->dportal;
	/*
	 * The wmb() flushes writes to coherent DMA data before possibly
	 * triggering a DMA read. The wmb() is necessary even on UP because
	 * the recipient is a device.
	 */
	wmb();
	iosubmit_cmds512(portal, desc->hw, 1);

	/*
	 * Pending the descriptor to the lockless list for the irq_entry
	 * that we designated the descriptor to.
	 */
	if (desc->hw->flags & IDXD_OP_FLAG_RCI)
		llist_add(&desc->llnode,
			  &idxd->irq_entries[vec].pending_llist);

	return 0;
}