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(objp: 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(objp: priv->sgts);
47 kfree(objp: 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(dev: priv->dev->parent->parent,
72 PAGE_SIZE, dma_handle: &sg_dma_address(sg_ptr),
73 GFP_KERNEL);
74 if (!block)
75 return -ENOMEM;
76
77 sg_set_buf(sg: sg_ptr, buf: 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(dev: priv->dev->parent->parent, PAGE_SIZE,
92 cpu_addr: sg_virt(sg: 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(dev: 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_DESCRIPTION("example software sink buffer for Intel TH MSU");
120MODULE_LICENSE("GPL v2");
121

source code of linux/drivers/hwtracing/intel_th/msu-sink.c