1 // SPDX-License-Identifier: GPL-2.0
3 * An example software sink buffer for Intel TH MSU.
5 * Copyright (C) 2019 Intel Corporation.
8 #include <linux/intel_th.h>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/device.h>
12 #include <linux/dma-mapping.h>
16 struct msu_sink_private {
18 struct sg_table **sgts;
22 static void *msu_sink_assign(struct device *dev, int *mode)
24 struct msu_sink_private *priv;
26 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
30 priv->sgts = kcalloc(MAX_SGTS, sizeof(void *), GFP_KERNEL);
37 *mode = MSC_MODE_MULTI;
42 static void msu_sink_unassign(void *data)
44 struct msu_sink_private *priv = data;
50 /* See also: msc.c: __msc_buffer_win_alloc() */
51 static int msu_sink_alloc_window(void *data, struct sg_table **sgt, size_t size)
53 struct msu_sink_private *priv = data;
55 struct scatterlist *sg_ptr;
59 if (priv->nr_sgts == MAX_SGTS)
62 nents = DIV_ROUND_UP(size, PAGE_SIZE);
64 ret = sg_alloc_table(*sgt, nents, GFP_KERNEL);
68 priv->sgts[priv->nr_sgts++] = *sgt;
70 for_each_sg((*sgt)->sgl, sg_ptr, nents, i) {
71 block = dma_alloc_coherent(priv->dev->parent->parent,
72 PAGE_SIZE, &sg_dma_address(sg_ptr),
77 sg_set_buf(sg_ptr, block, PAGE_SIZE);
83 /* See also: msc.c: __msc_buffer_win_free() */
84 static void msu_sink_free_window(void *data, struct sg_table *sgt)
86 struct msu_sink_private *priv = data;
87 struct scatterlist *sg_ptr;
90 for_each_sg(sgt->sgl, sg_ptr, sgt->nents, i) {
91 dma_free_coherent(priv->dev->parent->parent, PAGE_SIZE,
92 sg_virt(sg_ptr), sg_dma_address(sg_ptr));
99 static int msu_sink_ready(void *data, struct sg_table *sgt, size_t bytes)
101 struct msu_sink_private *priv = data;
103 intel_th_msc_window_unlock(priv->dev, sgt);
108 static const struct msu_buffer sink_mbuf = {
110 .assign = msu_sink_assign,
111 .unassign = msu_sink_unassign,
112 .alloc_window = msu_sink_alloc_window,
113 .free_window = msu_sink_free_window,
114 .ready = msu_sink_ready,
117 module_intel_th_msu_buffer(sink_mbuf);
119 MODULE_LICENSE("GPL v2");