ALSA: xen-front: Implement handling of shared buffers
Implement shared buffer handling according to the para-virtualized sound device protocol at xen/interface/io/sndif.h: - manage buffer memory - handle granted references - handle page directories [ Fixed missing linux/kernel.h inclusion -- tiwai ] Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Oleksandr Andrushchenko
Takashi Iwai
parent
788ef64a2c
commit
d6e0fbb82e
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@ -2,6 +2,7 @@
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snd_xen_front-objs := xen_snd_front.o \
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xen_snd_front_cfg.o \
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xen_snd_front_evtchnl.o
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xen_snd_front_evtchnl.o \
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xen_snd_front_shbuf.o
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obj-$(CONFIG_SND_XEN_FRONTEND) += snd_xen_front.o
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@ -11,6 +11,7 @@
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <xen/page.h>
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#include <xen/platform_pci.h>
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#include <xen/xen.h>
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#include <xen/xenbus.h>
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@ -191,6 +192,13 @@ static int __init xen_drv_init(void)
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if (!xen_has_pv_devices())
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return -ENODEV;
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/* At the moment we only support case with XEN_PAGE_SIZE == PAGE_SIZE */
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if (XEN_PAGE_SIZE != PAGE_SIZE) {
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pr_err(XENSND_DRIVER_NAME ": different kernel and Xen page sizes are not supported: XEN_PAGE_SIZE (%lu) != PAGE_SIZE (%lu)\n",
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XEN_PAGE_SIZE, PAGE_SIZE);
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return -ENODEV;
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}
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pr_info("Initialising Xen " XENSND_DRIVER_NAME " frontend driver\n");
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return xenbus_register_frontend(&xen_driver);
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}
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@ -0,0 +1,194 @@
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// SPDX-License-Identifier: GPL-2.0 OR MIT
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/*
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* Xen para-virtual sound device
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*
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* Copyright (C) 2016-2018 EPAM Systems Inc.
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*
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* Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
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*/
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#include <linux/kernel.h>
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#include <xen/xen.h>
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#include <xen/xenbus.h>
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#include "xen_snd_front_shbuf.h"
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grant_ref_t xen_snd_front_shbuf_get_dir_start(struct xen_snd_front_shbuf *buf)
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{
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if (!buf->grefs)
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return GRANT_INVALID_REF;
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return buf->grefs[0];
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}
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void xen_snd_front_shbuf_clear(struct xen_snd_front_shbuf *buf)
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{
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memset(buf, 0, sizeof(*buf));
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}
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void xen_snd_front_shbuf_free(struct xen_snd_front_shbuf *buf)
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{
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int i;
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if (buf->grefs) {
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for (i = 0; i < buf->num_grefs; i++)
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if (buf->grefs[i] != GRANT_INVALID_REF)
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gnttab_end_foreign_access(buf->grefs[i],
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0, 0UL);
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kfree(buf->grefs);
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}
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kfree(buf->directory);
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free_pages_exact(buf->buffer, buf->buffer_sz);
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xen_snd_front_shbuf_clear(buf);
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}
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/*
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* number of grant references a page can hold with respect to the
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* xensnd_page_directory header
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*/
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#define XENSND_NUM_GREFS_PER_PAGE ((XEN_PAGE_SIZE - \
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offsetof(struct xensnd_page_directory, gref)) / \
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sizeof(grant_ref_t))
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static void fill_page_dir(struct xen_snd_front_shbuf *buf,
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int num_pages_dir)
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{
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struct xensnd_page_directory *page_dir;
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unsigned char *ptr;
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int i, cur_gref, grefs_left, to_copy;
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ptr = buf->directory;
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grefs_left = buf->num_grefs - num_pages_dir;
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/*
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* skip grant references at the beginning, they are for pages granted
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* for the page directory itself
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*/
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cur_gref = num_pages_dir;
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for (i = 0; i < num_pages_dir; i++) {
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page_dir = (struct xensnd_page_directory *)ptr;
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if (grefs_left <= XENSND_NUM_GREFS_PER_PAGE) {
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to_copy = grefs_left;
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page_dir->gref_dir_next_page = GRANT_INVALID_REF;
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} else {
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to_copy = XENSND_NUM_GREFS_PER_PAGE;
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page_dir->gref_dir_next_page = buf->grefs[i + 1];
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}
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memcpy(&page_dir->gref, &buf->grefs[cur_gref],
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to_copy * sizeof(grant_ref_t));
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ptr += XEN_PAGE_SIZE;
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grefs_left -= to_copy;
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cur_gref += to_copy;
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}
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}
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static int grant_references(struct xenbus_device *xb_dev,
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struct xen_snd_front_shbuf *buf,
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int num_pages_dir, int num_pages_buffer,
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int num_grefs)
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{
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grant_ref_t priv_gref_head;
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unsigned long frame;
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int ret, i, j, cur_ref;
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int otherend_id;
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ret = gnttab_alloc_grant_references(num_grefs, &priv_gref_head);
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if (ret)
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return ret;
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buf->num_grefs = num_grefs;
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otherend_id = xb_dev->otherend_id;
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j = 0;
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for (i = 0; i < num_pages_dir; i++) {
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cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
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if (cur_ref < 0) {
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ret = cur_ref;
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goto fail;
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}
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frame = xen_page_to_gfn(virt_to_page(buf->directory +
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XEN_PAGE_SIZE * i));
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gnttab_grant_foreign_access_ref(cur_ref, otherend_id, frame, 0);
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buf->grefs[j++] = cur_ref;
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}
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for (i = 0; i < num_pages_buffer; i++) {
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cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
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if (cur_ref < 0) {
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ret = cur_ref;
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goto fail;
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}
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frame = xen_page_to_gfn(virt_to_page(buf->buffer +
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XEN_PAGE_SIZE * i));
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gnttab_grant_foreign_access_ref(cur_ref, otherend_id, frame, 0);
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buf->grefs[j++] = cur_ref;
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}
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gnttab_free_grant_references(priv_gref_head);
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fill_page_dir(buf, num_pages_dir);
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return 0;
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fail:
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gnttab_free_grant_references(priv_gref_head);
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return ret;
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}
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static int alloc_int_buffers(struct xen_snd_front_shbuf *buf,
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int num_pages_dir, int num_pages_buffer,
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int num_grefs)
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{
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buf->grefs = kcalloc(num_grefs, sizeof(*buf->grefs), GFP_KERNEL);
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if (!buf->grefs)
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return -ENOMEM;
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buf->directory = kcalloc(num_pages_dir, XEN_PAGE_SIZE, GFP_KERNEL);
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if (!buf->directory)
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goto fail;
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buf->buffer_sz = num_pages_buffer * XEN_PAGE_SIZE;
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buf->buffer = alloc_pages_exact(buf->buffer_sz, GFP_KERNEL);
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if (!buf->buffer)
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goto fail;
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return 0;
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fail:
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kfree(buf->grefs);
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buf->grefs = NULL;
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kfree(buf->directory);
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buf->directory = NULL;
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return -ENOMEM;
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}
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int xen_snd_front_shbuf_alloc(struct xenbus_device *xb_dev,
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struct xen_snd_front_shbuf *buf,
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unsigned int buffer_sz)
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{
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int num_pages_buffer, num_pages_dir, num_grefs;
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int ret;
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xen_snd_front_shbuf_clear(buf);
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num_pages_buffer = DIV_ROUND_UP(buffer_sz, XEN_PAGE_SIZE);
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/* number of pages the page directory consumes itself */
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num_pages_dir = DIV_ROUND_UP(num_pages_buffer,
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XENSND_NUM_GREFS_PER_PAGE);
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num_grefs = num_pages_buffer + num_pages_dir;
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ret = alloc_int_buffers(buf, num_pages_dir,
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num_pages_buffer, num_grefs);
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if (ret < 0)
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return ret;
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ret = grant_references(xb_dev, buf, num_pages_dir, num_pages_buffer,
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num_grefs);
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if (ret < 0)
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return ret;
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fill_page_dir(buf, num_pages_dir);
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return 0;
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}
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@ -0,0 +1,36 @@
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/* SPDX-License-Identifier: GPL-2.0 OR MIT */
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/*
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* Xen para-virtual sound device
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*
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* Copyright (C) 2016-2018 EPAM Systems Inc.
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*
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* Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
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*/
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#ifndef __XEN_SND_FRONT_SHBUF_H
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#define __XEN_SND_FRONT_SHBUF_H
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#include <xen/grant_table.h>
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#include "xen_snd_front_evtchnl.h"
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struct xen_snd_front_shbuf {
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int num_grefs;
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grant_ref_t *grefs;
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u8 *directory;
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u8 *buffer;
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size_t buffer_sz;
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};
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grant_ref_t xen_snd_front_shbuf_get_dir_start(struct xen_snd_front_shbuf *buf);
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int xen_snd_front_shbuf_alloc(struct xenbus_device *xb_dev,
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struct xen_snd_front_shbuf *buf,
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unsigned int buffer_sz);
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void xen_snd_front_shbuf_clear(struct xen_snd_front_shbuf *buf);
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void xen_snd_front_shbuf_free(struct xen_snd_front_shbuf *buf);
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#endif /* __XEN_SND_FRONT_SHBUF_H */
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