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(dev->of_node, 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_find_property(dev->of_node, "interconnects", NULL))
 86		return NOTIFY_DONE;
 87
 88	ret = dma_direct_set_offset(dev, PHYS_OFFSET, 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(of_root, sunxi_mbus_platforms))
122		return 0;
123
124	bus_register_notifier(&platform_bus_type, &sunxi_mbus_nb);
125	return 0;
126}
127arch_initcall(sunxi_mbus_init);