1// SPDX-License-Identifier: GPL-2.0
2/*
3 * An example software sink buffer for Intel TH MSU.
4 *
5 * Copyright (C) 2019 Intel Corporation.
6 */
7
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>
13
14#define MAX_SGTS 16
15
16struct msu_sink_private {
17	struct device	*dev;
18	struct sg_table **sgts;
19	unsigned int	nr_sgts;
20};
21
22static void *msu_sink_assign(struct device *dev, int *mode)
23{
24	struct msu_sink_private *priv;
25
26	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
27	if (!priv)
28		return NULL;
29
30	priv->sgts = kcalloc(MAX_SGTS, sizeof(void *), GFP_KERNEL);
31	if (!priv->sgts) {
32		kfree(priv);
33		return NULL;
34	}
35
36	priv->dev = dev;
37	*mode = MSC_MODE_MULTI;
38
39	return priv;
40}
41
42static void msu_sink_unassign(void *data)
43{
44	struct msu_sink_private *priv = data;
45
46	kfree(priv->sgts);
47	kfree(priv);
48}
49
50/* See also: msc.c: __msc_buffer_win_alloc() */
51static int msu_sink_alloc_window(void *data, struct sg_table **sgt, size_t size)
52{
53	struct msu_sink_private *priv = data;
54	unsigned int nents;
55	struct scatterlist *sg_ptr;
56	void *block;
57	int ret, i;
58
59	if (priv->nr_sgts == MAX_SGTS)
60		return -ENOMEM;
61
62	nents = DIV_ROUND_UP(size, PAGE_SIZE);
63
64	ret = sg_alloc_table(*sgt, nents, GFP_KERNEL);
65	if (ret)
66		return -ENOMEM;
67
68	priv->sgts[priv->nr_sgts++] = *sgt;
69
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),
73					   GFP_KERNEL);
74		if (!block)
75			return -ENOMEM;
76
77		sg_set_buf(sg_ptr, block, PAGE_SIZE);
78	}
79
80	return nents;
81}
82
83/* See also: msc.c: __msc_buffer_win_free() */
84static void msu_sink_free_window(void *data, struct sg_table *sgt)
85{
86	struct msu_sink_private *priv = data;
87	struct scatterlist *sg_ptr;
88	int i;
89
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));
93	}
94
95	sg_free_table(sgt);
96	priv->nr_sgts--;
97}
98
99static int msu_sink_ready(void *data, struct sg_table *sgt, size_t bytes)
100{
101	struct msu_sink_private *priv = data;
102
103	intel_th_msc_window_unlock(priv->dev, sgt);
104
105	return 0;
106}
107
108static const struct msu_buffer sink_mbuf = {
109	.name		= "sink",
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,
115};
116
117module_intel_th_msu_buffer(sink_mbuf);
118
119MODULE_LICENSE("GPL v2");
120