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 11 static 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 60 static 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_property_present(dev->of_node, "interconnects")) 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 95 static struct notifier_block sunxi_mbus_nb = { 96 .notifier_call = sunxi_mbus_notifier, 97 }; 98 99 static 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 }; 118 119 static 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 } 127 arch_initcall(sunxi_mbus_init); 128