1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (C) 2020 Maxime Ripard <maxime@cerno.tech> */
3
4#include <linux/device.h>
5#include <linux/dma-map-ops.h>
6#include <linux/init.h>
7#include <linux/notifier.h>
8#include <linux/of.h>
9#include <linux/platform_device.h>
10
11static const char * const sunxi_mbus_devices[] = {
12 /*
13 * The display engine virtual devices are not strictly speaking
14 * connected to the MBUS, but since DRM will perform all the
15 * memory allocations and DMA operations through that device, we
16 * need to have the quirk on those devices too.
17 */
18 "allwinner,sun4i-a10-display-engine",
19 "allwinner,sun5i-a10s-display-engine",
20 "allwinner,sun5i-a13-display-engine",
21 "allwinner,sun6i-a31-display-engine",
22 "allwinner,sun6i-a31s-display-engine",
23 "allwinner,sun7i-a20-display-engine",
24 "allwinner,sun8i-a23-display-engine",
25 "allwinner,sun8i-a33-display-engine",
26 "allwinner,sun9i-a80-display-engine",
27
28 /*
29 * And now we have the regular devices connected to the MBUS
30 * (that we know of).
31 */
32 "allwinner,sun4i-a10-csi1",
33 "allwinner,sun4i-a10-display-backend",
34 "allwinner,sun4i-a10-display-frontend",
35 "allwinner,sun4i-a10-video-engine",
36 "allwinner,sun5i-a13-display-backend",
37 "allwinner,sun5i-a13-video-engine",
38 "allwinner,sun6i-a31-csi",
39 "allwinner,sun6i-a31-display-backend",
40 "allwinner,sun7i-a20-csi0",
41 "allwinner,sun7i-a20-display-backend",
42 "allwinner,sun7i-a20-display-frontend",
43 "allwinner,sun7i-a20-video-engine",
44 "allwinner,sun8i-a23-display-backend",
45 "allwinner,sun8i-a23-display-frontend",
46 "allwinner,sun8i-a33-display-backend",
47 "allwinner,sun8i-a33-display-frontend",
48 "allwinner,sun8i-a33-video-engine",
49 "allwinner,sun8i-a83t-csi",
50 "allwinner,sun8i-h3-csi",
51 "allwinner,sun8i-h3-video-engine",
52 "allwinner,sun8i-v3s-csi",
53 "allwinner,sun9i-a80-display-backend",
54 "allwinner,sun50i-a64-csi",
55 "allwinner,sun50i-a64-video-engine",
56 "allwinner,sun50i-h5-video-engine",
57 NULL,
58};
59
60static int sunxi_mbus_notifier(struct notifier_block *nb,
61 unsigned long event, void *__dev)
62{
63 struct device *dev = __dev;
64 int ret;
65
66 if (event != BUS_NOTIFY_ADD_DEVICE)
67 return NOTIFY_DONE;
68
69 /*
70 * Only the devices that need a large memory bandwidth do DMA
71 * directly over the memory bus (called MBUS), instead of going
72 * through the regular system bus.
73 */
74 if (!of_device_compatible_match(device: dev->of_node, compat: sunxi_mbus_devices))
75 return NOTIFY_DONE;
76
77 /*
78 * Devices with an interconnects property have the MBUS
79 * relationship described in their DT and dealt with by
80 * of_dma_configure, so we can just skip them.
81 *
82 * Older DTs or SoCs who are not clearly understood need to set
83 * that DMA offset though.
84 */
85 if (of_property_present(np: dev->of_node, propname: "interconnects"))
86 return NOTIFY_DONE;
87
88 ret = dma_direct_set_offset(dev, cpu_start: PHYS_OFFSET, dma_start: 0, SZ_4G);
89 if (ret)
90 dev_err(dev, "Couldn't setup our DMA offset: %d\n", ret);
91
92 return NOTIFY_DONE;
93}
94
95static struct notifier_block sunxi_mbus_nb = {
96 .notifier_call = sunxi_mbus_notifier,
97};
98
99static const char * const sunxi_mbus_platforms[] __initconst = {
100 "allwinner,sun4i-a10",
101 "allwinner,sun5i-a10s",
102 "allwinner,sun5i-a13",
103 "allwinner,sun6i-a31",
104 "allwinner,sun7i-a20",
105 "allwinner,sun8i-a23",
106 "allwinner,sun8i-a33",
107 "allwinner,sun8i-a83t",
108 "allwinner,sun8i-h3",
109 "allwinner,sun8i-r40",
110 "allwinner,sun8i-v3",
111 "allwinner,sun8i-v3s",
112 "allwinner,sun9i-a80",
113 "allwinner,sun50i-a64",
114 "allwinner,sun50i-h5",
115 "nextthing,gr8",
116 NULL,
117};
118
119static int __init sunxi_mbus_init(void)
120{
121 if (!of_device_compatible_match(device: of_root, compat: sunxi_mbus_platforms))
122 return 0;
123
124 bus_register_notifier(bus: &platform_bus_type, nb: &sunxi_mbus_nb);
125 return 0;
126}
127arch_initcall(sunxi_mbus_init);
128

source code of linux/drivers/soc/sunxi/sunxi_mbus.c