drivers/soc/sunxi/sunxi_mbus.c

   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);