Re: [PATCH v3 7/9] bus: fsl-mc: dpio: add the DPAA2 DPIO service interface

[Laurentiu Tudor]

On 12/02/2016 12:41 AM, Stuart Yoder wrote:
> From: Roy Pledge <Roy.Pledge@xxxxxxx>
> 
> The DPIO service interface handles initialization of DPIO objects
> and exports APIs to be used by other DPAA2 object drivers to perform
> queuing and buffer management related operations.  The service allows
> registration of callbacks when frames or notifications are received.
> 
> Signed-off-by: Roy Pledge <roy.pledge@xxxxxxx>
> Signed-off-by: Haiying Wang <haiying.wang@xxxxxxx>
> Signed-off-by: Stuart Yoder <stuart.yoder@xxxxxxx>
> ---
> 
> Notes:
>     -v3
>        -zero memory allocated for a dpio store (bug fix suggested
>         by Ioana Radulescu)
>     -v2
>        -use service_select_by_cpu() for re-arming DPIO interrupts
>        -replace use of NR_CPUS with num_possible_cpus()
> 
>  drivers/bus/fsl-mc/dpio/Makefile       |   2 +-
>  drivers/bus/fsl-mc/dpio/dpio-service.c | 614 +++++++++++++++++++++++++++++++++
>  include/linux/fsl/dpaa2-io.h           | 138 ++++++++
>  3 files changed, 753 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/bus/fsl-mc/dpio/dpio-service.c
>  create mode 100644 include/linux/fsl/dpaa2-io.h
> 
> diff --git a/drivers/bus/fsl-mc/dpio/Makefile b/drivers/bus/fsl-mc/dpio/Makefile
> index 6588498..0778da7 100644
> --- a/drivers/bus/fsl-mc/dpio/Makefile
> +++ b/drivers/bus/fsl-mc/dpio/Makefile
> @@ -6,4 +6,4 @@ subdir-ccflags-y := -Werror
>  
>  obj-$(CONFIG_FSL_MC_DPIO) += fsl-mc-dpio.o
>  
> -fsl-mc-dpio-objs := dpio.o qbman-portal.o
> +fsl-mc-dpio-objs := dpio.o qbman-portal.o dpio-service.o
> diff --git a/drivers/bus/fsl-mc/dpio/dpio-service.c b/drivers/bus/fsl-mc/dpio/dpio-service.c
> new file mode 100644
> index 0000000..01f0293
> --- /dev/null
> +++ b/drivers/bus/fsl-mc/dpio/dpio-service.c
> @@ -0,0 +1,614 @@
> +/*
> + * Copyright 2014-2016 Freescale Semiconductor Inc.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are met:
> + *     * Redistributions of source code must retain the above copyright
> + *	 notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *	 notice, this list of conditions and the following disclaimer in the
> + *	 documentation and/or other materials provided with the distribution.
> + *     * Neither the name of Freescale Semiconductor nor the
> + *	 names of its contributors may be used to endorse or promote products
> + *	 derived from this software without specific prior written permission.
> + *
> + *
> + * ALTERNATIVELY, this software may be distributed under the terms of the
> + * GNU General Public License ("GPL") as published by the Free Software
> + * Foundation, either version 2 of that License or (at your option) any
> + * later version.
> + *
> + * THIS SOFTWARE IS PROVIDED BY Freescale Semiconductor ``AS IS'' AND ANY
> + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL Freescale Semiconductor BE LIABLE FOR ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +#include <linux/types.h>
> +#include <linux/fsl/mc.h>
> +#include <linux/fsl/dpaa2-io.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/interrupt.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/slab.h>
> +
> +#include "dpio.h"
> +#include "qbman-portal.h"
> +
> +struct dpaa2_io {
> +	atomic_t refs;
> +	struct dpaa2_io_desc dpio_desc;
> +	struct qbman_swp_desc swp_desc;
> +	struct qbman_swp *swp;
> +	struct list_head node;
> +	spinlock_t lock_mgmt_cmd;
> +	spinlock_t lock_notifications;
> +	struct list_head notifications;
> +};
> +
> +struct dpaa2_io_store {
> +	unsigned int max;
> +	dma_addr_t paddr;
> +	struct dpaa2_dq *vaddr;
> +	void *alloced_addr;    /* unaligned value from kmalloc() */
> +	unsigned int idx;      /* position of the next-to-be-returned entry */
> +	struct qbman_swp *swp; /* portal used to issue VDQCR */
> +	struct device *dev;    /* device used for DMA mapping */
> +};
> +
> +/* keep a per cpu array of DPIOs for fast access */
> +static struct dpaa2_io *dpio_by_cpu[NR_CPUS];
> +static struct list_head dpio_list = LIST_HEAD_INIT(dpio_list);
> +static DEFINE_SPINLOCK(dpio_list_lock);
> +
> +static inline struct dpaa2_io *service_select_by_cpu(struct dpaa2_io *d,
> +						     int cpu)
> +{
> +	if (d)
> +		return d;
> +
> +	if (unlikely(cpu >= num_possible_cpus()))
> +		return NULL;
> +
> +	/*
> +	 * If cpu == -1, choose the current cpu, with no guarantees about
> +	 * potentially being migrated away.
> +	 */
> +	if (unlikely(cpu < 0))
> +		cpu = smp_processor_id();
> +
> +	/* If a specific cpu was requested, pick it up immediately */
> +	return dpio_by_cpu[cpu];
> +}
> +
> +static inline struct dpaa2_io *service_select(struct dpaa2_io *d)
> +{
> +	if (d)
> +		return d;
> +
> +	spin_lock(&dpio_list_lock);
> +	d = list_entry(dpio_list.next, struct dpaa2_io, node);
> +	list_del(&d->node);
> +	list_add_tail(&d->node, &dpio_list);
> +	spin_unlock(&dpio_list_lock);
> +
> +	return d;
> +}
> +
> +/**
> + * dpaa2_io_create() - create a dpaa2_io object.
> + * @desc: the dpaa2_io descriptor
> + *
> + * Activates a "struct dpaa2_io" corresponding to the given config of an actual
> + * DPIO object.
> + *
> + * Return a valid dpaa2_io object for success, or NULL for failure.
> + */
> +struct dpaa2_io *dpaa2_io_create(const struct dpaa2_io_desc *desc)
> +{
> +	struct dpaa2_io *obj = kmalloc(sizeof(*obj), GFP_KERNEL);
> +
> +	if (!obj)
> +		return NULL;
> +
> +	/* check if CPU is out of range (-1 means any cpu) */
> +	if (desc->cpu >= num_possible_cpus())

We leak 'obj' on this error path.

> +		return NULL;
> +
> +	atomic_set(&obj->refs, 1);
> +	obj->dpio_desc = *desc;
> +	obj->swp_desc.cena_bar = obj->dpio_desc.regs_cena;
> +	obj->swp_desc.cinh_bar = obj->dpio_desc.regs_cinh;
> +	obj->swp_desc.qman_version = obj->dpio_desc.qman_version;
> +	obj->swp = qbman_swp_init(&obj->swp_desc);
> +
> +	if (!obj->swp) {
> +		kfree(obj);
> +		return NULL;
> +	}
> +
> +	INIT_LIST_HEAD(&obj->node);
> +	spin_lock_init(&obj->lock_mgmt_cmd);
> +	spin_lock_init(&obj->lock_notifications);
> +	INIT_LIST_HEAD(&obj->notifications);
> +
> +	/* For now only enable DQRR interrupts */
> +	qbman_swp_interrupt_set_trigger(obj->swp,
> +					QBMAN_SWP_INTERRUPT_DQRI);
> +	qbman_swp_interrupt_clear_status(obj->swp, 0xffffffff);
> +	if (obj->dpio_desc.receives_notifications)
> +		qbman_swp_push_set(obj->swp, 0, 1);
> +
> +	spin_lock(&dpio_list_lock);
> +	list_add_tail(&obj->node, &dpio_list);
> +	if (desc->cpu >= 0 && !dpio_by_cpu[desc->cpu])
> +		dpio_by_cpu[desc->cpu] = obj;
> +	spin_unlock(&dpio_list_lock);
> +
> +	return obj;
> +}
> +EXPORT_SYMBOL(dpaa2_io_create);
> +
> +/**
> + * dpaa2_io_down() - release the dpaa2_io object.
> + * @d: the dpaa2_io object to be released.
> + *
> + * The "struct dpaa2_io" type can represent an individual DPIO object (as
> + * described by "struct dpaa2_io_desc") or an instance of a "DPIO service",
> + * which can be used to group/encapsulate multiple DPIO objects. In all cases,
> + * each handle obtained should be released using this function.
> + */
> +void dpaa2_io_down(struct dpaa2_io *d)
> +{
> +	if (!atomic_dec_and_test(&d->refs))
> +		return;
> +	kfree(d);
> +}
> +EXPORT_SYMBOL(dpaa2_io_down);
> +
> +#define DPAA_POLL_MAX 32
> +
> +/**
> + * dpaa2_io_irq() - ISR for DPIO interrupts
> + *
> + * @obj: the given DPIO object.
> + *
> + * Return IRQ_HANDLED for success or IRQ_NONE if there
> + * were no pending interrupts.
> + */
> +irqreturn_t dpaa2_io_irq(struct dpaa2_io *obj)
> +{
> +	const struct dpaa2_dq *dq;
> +	int max = 0;
> +	struct qbman_swp *swp;
> +	u32 status;
> +
> +	swp = obj->swp;
> +	status = qbman_swp_interrupt_read_status(swp);
> +	if (!status)
> +		return IRQ_NONE;
> +
> +	dq = qbman_swp_dqrr_next(swp);
> +	while (dq) {
> +		if (qbman_result_is_SCN(dq)) {
> +			struct dpaa2_io_notification_ctx *ctx;
> +			u64 q64;
> +
> +			q64 = qbman_result_SCN_ctx(dq);
> +			ctx = (void *)q64;
> +			ctx->cb(ctx);
> +		} else {
> +			pr_crit("fsl-mc-dpio: Unrecognised/ignored DQRR entry\n");
> +		}
> +		qbman_swp_dqrr_consume(swp, dq);
> +		++max;
> +		if (max > DPAA_POLL_MAX)
> +			goto done;
> +		dq = qbman_swp_dqrr_next(swp);
> +	}
> +done:
> +	qbman_swp_interrupt_clear_status(swp, status);
> +	qbman_swp_interrupt_set_inhibit(swp, 0);
> +	return IRQ_HANDLED;
> +}
> +EXPORT_SYMBOL(dpaa2_io_irq);
> +
> +/**
> + * dpaa2_io_service_register() - Prepare for servicing of FQDAN or CDAN
> + *                               notifications on the given DPIO service.
> + * @d:   the given DPIO service.
> + * @ctx: the notification context.
> + *
> + * The caller should make the MC command to attach a DPAA2 object to
> + * a DPIO after this function completes successfully.  In that way:
> + *    (a) The DPIO service is "ready" to handle a notification arrival
> + *        (which might happen before the "attach" command to MC has
> + *        returned control of execution back to the caller)
> + *    (b) The DPIO service can provide back to the caller the 'dpio_id' and
> + *        'qman64' parameters that it should pass along in the MC command
> + *        in order for the object to be configured to produce the right
> + *        notification fields to the DPIO service.
> + *
> + * Return 0 for success, or -ENODEV for failure.
> + */
> +int dpaa2_io_service_register(struct dpaa2_io *d,
> +			      struct dpaa2_io_notification_ctx *ctx)
> +{
> +	unsigned long irqflags;
> +
> +	d = service_select_by_cpu(d, ctx->desired_cpu);
> +	if (!d)
> +		return -ENODEV;
> +
> +	ctx->dpio_id = d->dpio_desc.dpio_id;
> +	ctx->qman64 = (u64)ctx;
> +	ctx->dpio_private = d;
> +	spin_lock_irqsave(&d->lock_notifications, irqflags);
> +	list_add(&ctx->node, &d->notifications);
> +	spin_unlock_irqrestore(&d->lock_notifications, irqflags);
> +
> +	/* Enable the generation of CDAN notifications */
> +	if (ctx->is_cdan)
> +		qbman_swp_CDAN_set_context_enable(d->swp,
> +						  (u16)ctx->id,
> +						  ctx->qman64);
> +	return 0;
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_register);
> +
> +/**
> + * dpaa2_io_service_deregister - The opposite of 'register'.
> + * @service: the given DPIO service.
> + * @ctx: the notification context.
> + *
> + * This function should be called only after sending the MC command to
> + * to detach the notification-producing device from the DPIO.
> + */
> +void dpaa2_io_service_deregister(struct dpaa2_io *service,
> +				struct dpaa2_io_notification_ctx *ctx)
> +{
> +	struct dpaa2_io *d = ctx->dpio_private;
> +	unsigned long irqflags;
> +
> +	if (ctx->is_cdan)
> +		qbman_swp_CDAN_disable(d->swp, (u16)ctx->id);
> +
> +	spin_lock_irqsave(&d->lock_notifications, irqflags);
> +	list_del(&ctx->node);
> +	spin_unlock_irqrestore(&d->lock_notifications, irqflags);
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_deregister);
> +
> +/**
> + * dpaa2_io_service_rearm() - Rearm the notification for the given DPIO service.
> + * @service: the given DPIO service.

s/@service/@d/

> + * @ctx: the notification context.
> + *
> + * Once a FQDAN/CDAN has been produced, the corresponding FQ/channel is
> + * considered "disarmed". Ie. the user can issue pull dequeue operations on that
> + * traffic source for as long as it likes. Eventually it may wish to "rearm"
> + * that source to allow it to produce another FQDAN/CDAN, that's what this
> + * function achieves.
> + *
> + * Return 0 for success.
> + */
> +int dpaa2_io_service_rearm(struct dpaa2_io *d,
> +			   struct dpaa2_io_notification_ctx *ctx)
> +{
> +	unsigned long irqflags;
> +	int err;
> +
> +	d = service_select_by_cpu(d, ctx->desired_cpu);
> +	if (!unlikely(d))
> +		return -ENODEV;
> +
> +	spin_lock_irqsave(&d->lock_mgmt_cmd, irqflags);
> +	if (ctx->is_cdan)
> +		err = qbman_swp_CDAN_enable(d->swp, (u16)ctx->id);
> +	else
> +		err = qbman_swp_fq_schedule(d->swp, ctx->id);
> +	spin_unlock_irqrestore(&d->lock_mgmt_cmd, irqflags);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_rearm);
> +
> +/**
> + * dpaa2_io_service_pull_fq() - pull dequeue functions from a fq.
> + * @d: the given DPIO service.
> + * @fqid: the given frame queue id.
> + * @s: the dpaa2_io_store object for the result.
> + *
> + * Return 0 for success, or error code for failure.
> + */
> +int dpaa2_io_service_pull_fq(struct dpaa2_io *d, u32 fqid,
> +			     struct dpaa2_io_store *s)
> +{
> +	struct qbman_pull_desc pd;
> +	int err;
> +
> +	qbman_pull_desc_clear(&pd);
> +	qbman_pull_desc_set_storage(&pd, s->vaddr, s->paddr, 1);
> +	qbman_pull_desc_set_numframes(&pd, (u8)s->max);
> +	qbman_pull_desc_set_fq(&pd, fqid);
> +
> +	d = service_select(d);
> +	if (!d)
> +		return -ENODEV;
> +	s->swp = d->swp;
> +	err = qbman_swp_pull(d->swp, &pd);
> +	if (err)
> +		s->swp = NULL;
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_pull_fq);
> +
> +/**
> + * dpaa2_io_service_pull_channel() - pull dequeue functions from a channel.
> + * @d: the given DPIO service.
> + * @channelid: the given channel id.
> + * @s: the dpaa2_io_store object for the result.
> + *
> + * Return 0 for success, or error code for failure.
> + */
> +int dpaa2_io_service_pull_channel(struct dpaa2_io *d, u32 channelid,
> +				  struct dpaa2_io_store *s)
> +{
> +	struct qbman_pull_desc pd;
> +	int err;
> +
> +	qbman_pull_desc_clear(&pd);
> +	qbman_pull_desc_set_storage(&pd, s->vaddr, s->paddr, 1);
> +	qbman_pull_desc_set_numframes(&pd, (u8)s->max);
> +	qbman_pull_desc_set_channel(&pd, channelid, qbman_pull_type_prio);
> +
> +	d = service_select(d);
> +	if (!d)
> +		return -ENODEV;
> +
> +	s->swp = d->swp;
> +	err = qbman_swp_pull(d->swp, &pd);
> +	if (err)
> +		s->swp = NULL;
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_pull_channel);
> +
> +/**
> + * dpaa2_io_service_enqueue_fq() - Enqueue a frame to a frame queue.
> + * @d: the given DPIO service.
> + * @fqid: the given frame queue id.
> + * @fd: the frame descriptor which is enqueued.
> + *
> + * Return 0 for successful enqueue, -EBUSY if the enqueue ring is not ready,
> + * or -ENODEV if there is no dpio service.
> + */
> +int dpaa2_io_service_enqueue_fq(struct dpaa2_io *d,
> +				u32 fqid,
> +				const struct dpaa2_fd *fd)
> +{
> +	struct qbman_eq_desc ed;
> +
> +	d = service_select(d);
> +	if (!d)
> +		return -ENODEV;
> +
> +	qbman_eq_desc_clear(&ed);
> +	qbman_eq_desc_set_no_orp(&ed, 0);
> +	qbman_eq_desc_set_fq(&ed, fqid);
> +
> +	return qbman_swp_enqueue(d->swp, &ed, fd);
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_enqueue_fq);
> +
> +/**
> + * dpaa2_io_service_enqueue_qd() - Enqueue a frame to a QD.
> + * @d: the given DPIO service.
> + * @qdid: the given queuing destination id.
> + * @prio: the given queuing priority.
> + * @qdbin: the given queuing destination bin.
> + * @fd: the frame descriptor which is enqueued.
> + *
> + * Return 0 for successful enqueue, or -EBUSY if the enqueue ring is not ready,
> + * or -ENODEV if there is no dpio service.
> + */
> +int dpaa2_io_service_enqueue_qd(struct dpaa2_io *d,
> +				u32 qdid, u8 prio, u16 qdbin,
> +				const struct dpaa2_fd *fd)
> +{
> +	struct qbman_eq_desc ed;
> +
> +	d = service_select(d);
> +	if (!d)
> +		return -ENODEV;
> +
> +	qbman_eq_desc_clear(&ed);
> +	qbman_eq_desc_set_no_orp(&ed, 0);
> +	qbman_eq_desc_set_qd(&ed, qdid, qdbin, prio);
> +
> +	return qbman_swp_enqueue(d->swp, &ed, fd);
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_enqueue_qd);
> +
> +/**
> + * dpaa2_io_service_release() - Release buffers to a buffer pool.
> + * @d: the given DPIO object.
> + * @bpid: the buffer pool id.
> + * @buffers: the buffers to be released.
> + * @num_buffers: the number of the buffers to be released.
> + *
> + * Return 0 for success, and negative error code for failure.
> + */
> +int dpaa2_io_service_release(struct dpaa2_io *d,
> +			     u32 bpid,
> +			     const u64 *buffers,
> +			     unsigned int num_buffers)
> +{
> +	struct qbman_release_desc rd;
> +
> +	d = service_select(d);
> +	if (!d)
> +		return -ENODEV;
> +
> +	qbman_release_desc_clear(&rd);
> +	qbman_release_desc_set_bpid(&rd, bpid);
> +
> +	return qbman_swp_release(d->swp, &rd, buffers, num_buffers);
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_release);
> +
> +/**
> + * dpaa2_io_service_acquire() - Acquire buffers from a buffer pool.
> + * @d: the given DPIO object.
> + * @bpid: the buffer pool id.
> + * @buffers: the buffer addresses for acquired buffers.
> + * @num_buffers: the expected number of the buffers to acquire.
> + *
> + * Return a negative error code if the command failed, otherwise it returns
> + * the number of buffers acquired, which may be less than the number requested.
> + * Eg. if the buffer pool is empty, this will return zero.
> + */
> +int dpaa2_io_service_acquire(struct dpaa2_io *d,
> +			     u32 bpid,
> +			     u64 *buffers,
> +			     unsigned int num_buffers)
> +{
> +	unsigned long irqflags;
> +	int err;
> +
> +	d = service_select(d);
> +	if (!d)
> +		return -ENODEV;
> +
> +	spin_lock_irqsave(&d->lock_mgmt_cmd, irqflags);
> +	err = qbman_swp_acquire(d->swp, bpid, buffers, num_buffers);
> +	spin_unlock_irqrestore(&d->lock_mgmt_cmd, irqflags);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(dpaa2_io_service_acquire);
> +
> +/*
> + * 'Stores' are reusable memory blocks for holding dequeue results, and to
> + * assist with parsing those results.
> + */
> +
> +/**
> + * dpaa2_io_store_create() - Create the dma memory storage for dequeue result.
> + * @max_frames: the maximum number of dequeued result for frames, must be <= 16.
> + * @dev:        the device to allow mapping/unmapping the DMAable region.
> + *
> + * The size of the storage is "max_frames*sizeof(struct dpaa2_dq)".
> + * The 'dpaa2_io_store' returned is a DPIO service managed object.
> + *
> + * Return pointer to dpaa2_io_store struct for successfuly created storage
> + * memory, or NULL on error.
> + */
> +struct dpaa2_io_store *dpaa2_io_store_create(unsigned int max_frames,
> +					     struct device *dev)
> +{
> +	struct dpaa2_io_store *ret;
> +	size_t size;
> +
> +	if (!max_frames || (max_frames > 16))
> +		return NULL;
> +
> +	ret = kmalloc(sizeof(*ret), GFP_KERNEL);
> +	if (!ret)
> +		return NULL;
> +
> +	ret->max = max_frames;
> +	size = max_frames * sizeof(struct dpaa2_dq) + 64;
> +	ret->alloced_addr = kzalloc(size, GFP_KERNEL);
> +	if (!ret->alloced_addr) {
> +		kfree(ret);
> +		return NULL;
> +	}
> +
> +	ret->vaddr = PTR_ALIGN(ret->alloced_addr, 64);
> +	ret->paddr = dma_map_single(dev, ret->vaddr,
> +				    sizeof(struct dpaa2_dq) * max_frames,
> +				    DMA_FROM_DEVICE);
> +	if (dma_mapping_error(dev, ret->paddr)) {
> +		kfree(ret->alloced_addr);
> +		kfree(ret);
> +		return NULL;
> +	}
> +
> +	ret->idx = 0;
> +	ret->dev = dev;
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(dpaa2_io_store_create);
> +
> +/**
> + * dpaa2_io_store_destroy() - Frees the dma memory storage for dequeue
> + *                            result.
> + * @s: the storage memory to be destroyed.
> + */
> +void dpaa2_io_store_destroy(struct dpaa2_io_store *s)
> +{
> +	dma_unmap_single(s->dev, s->paddr, sizeof(struct dpaa2_dq) * s->max,
> +			 DMA_FROM_DEVICE);
> +	kfree(s->alloced_addr);
> +	kfree(s);
> +}
> +EXPORT_SYMBOL(dpaa2_io_store_destroy);
> +
> +/**
> + * dpaa2_io_store_next() - Determine when the next dequeue result is available.
> + * @s: the dpaa2_io_store object.
> + * @is_last: indicate whether this is the last frame in the pull command.
> + *
> + * When an object driver performs dequeues to a dpaa2_io_store, this function
> + * can be used to determine when the next frame result is available. Once
> + * this function returns non-NULL, a subsequent call to it will try to find
> + * the next dequeue result.
> + *
> + * Note that if a pull-dequeue has a NULL result because the target FQ/channel
> + * was empty, then this function will also return NULL (rather than expecting
> + * the caller to always check for this. As such, "is_last" can be used to
> + * differentiate between "end-of-empty-dequeue" and "still-waiting".
> + *
> + * Return dequeue result for a valid dequeue result, or NULL for empty dequeue.
> + */
> +struct dpaa2_dq *dpaa2_io_store_next(struct dpaa2_io_store *s, int *is_last)

"bool *is_last"?

---
Best Regards, Laurentiu