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 | |
16 | struct msu_sink_private { |
17 | struct device *dev; |
18 | struct sg_table **sgts; |
19 | unsigned int nr_sgts; |
20 | }; |
21 | |
22 | static void *msu_sink_assign(struct device *dev, int *mode) |
23 | { |
24 | struct msu_sink_private *priv; |
25 | |
26 | priv = kzalloc(size: sizeof(*priv), GFP_KERNEL); |
27 | if (!priv) |
28 | return NULL; |
29 | |
30 | priv->sgts = kcalloc(MAX_SGTS, size: 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 | |
42 | static 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() */ |
51 | static 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() */ |
84 | static 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 | |
99 | static 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 | |
108 | static 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 | |
117 | module_intel_th_msu_buffer(sink_mbuf); |
118 | |
119 | MODULE_LICENSE("GPL v2" ); |
120 | |