Quelle  sunxi_mbus.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2020 Maxime Ripard <maxime@cerno.tech> */

#include <linux/device.h>
#include <linux/dma-map-ops.h>
#include <linux/init.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/platform_device.h>

static const char * const sunxi_mbus_devices[] = {
 /*
 * The display engine virtual devices are not strictly speaking
 * connected to the MBUS, but since DRM will perform all the
 * memory allocations and DMA operations through that device, we
 * need to have the quirk on those devices too.
 */
 "allwinner,sun4i-a10-display-engine",
 "allwinner,sun5i-a10s-display-engine",
 "allwinner,sun5i-a13-display-engine",
 "allwinner,sun6i-a31-display-engine",
 "allwinner,sun6i-a31s-display-engine",
 "allwinner,sun7i-a20-display-engine",
 "allwinner,sun8i-a23-display-engine",
 "allwinner,sun8i-a33-display-engine",
 "allwinner,sun9i-a80-display-engine",

 /*
 * And now we have the regular devices connected to the MBUS
 * (that we know of).
 */
 "allwinner,sun4i-a10-csi1",
 "allwinner,sun4i-a10-display-backend",
 "allwinner,sun4i-a10-display-frontend",
 "allwinner,sun4i-a10-video-engine",
 "allwinner,sun5i-a13-display-backend",
 "allwinner,sun5i-a13-video-engine",
 "allwinner,sun6i-a31-csi",
 "allwinner,sun6i-a31-display-backend",
 "allwinner,sun7i-a20-csi0",
 "allwinner,sun7i-a20-display-backend",
 "allwinner,sun7i-a20-display-frontend",
 "allwinner,sun7i-a20-video-engine",
 "allwinner,sun8i-a23-display-backend",
 "allwinner,sun8i-a23-display-frontend",
 "allwinner,sun8i-a33-display-backend",
 "allwinner,sun8i-a33-display-frontend",
 "allwinner,sun8i-a33-video-engine",
 "allwinner,sun8i-a83t-csi",
 "allwinner,sun8i-h3-csi",
 "allwinner,sun8i-h3-video-engine",
 "allwinner,sun8i-v3s-csi",
 "allwinner,sun9i-a80-display-backend",
 "allwinner,sun50i-a64-csi",
 "allwinner,sun50i-a64-video-engine",
 "allwinner,sun50i-h5-video-engine",
 NULL,
};

static int sunxi_mbus_notifier(struct notifier_block *nb,
          unsigned long event, void *__dev)
{
 struct device *dev = __dev;
 int ret;

 if (event != BUS_NOTIFY_ADD_DEVICE)
  return NOTIFY_DONE;

 /*
 * Only the devices that need a large memory bandwidth do DMA
 * directly over the memory bus (called MBUS), instead of going
 * through the regular system bus.
 */
 if (!of_device_compatible_match(dev->of_node, sunxi_mbus_devices))
  return NOTIFY_DONE;

 /*
 * Devices with an interconnects property have the MBUS
 * relationship described in their DT and dealt with by
 * of_dma_configure, so we can just skip them.
 *
 * Older DTs or SoCs who are not clearly understood need to set
 * that DMA offset though.
 */
 if (of_property_present(dev->of_node, "interconnects"))
  return NOTIFY_DONE;

 ret = dma_direct_set_offset(dev, PHYS_OFFSET, 0, SZ_4G);
 if (ret)
  dev_err(dev, "Couldn't setup our DMA offset: %d\n", ret);

 return NOTIFY_DONE;
}

static struct notifier_block sunxi_mbus_nb = {
 .notifier_call = sunxi_mbus_notifier,
};

static const char * const sunxi_mbus_platforms[] __initconst = {
 "allwinner,sun4i-a10",
 "allwinner,sun5i-a10s",
 "allwinner,sun5i-a13",
 "allwinner,sun6i-a31",
 "allwinner,sun7i-a20",
 "allwinner,sun8i-a23",
 "allwinner,sun8i-a33",
 "allwinner,sun8i-a83t",
 "allwinner,sun8i-h3",
 "allwinner,sun8i-r40",
 "allwinner,sun8i-v3",
 "allwinner,sun8i-v3s",
 "allwinner,sun9i-a80",
 "allwinner,sun50i-a64",
 "allwinner,sun50i-h5",
 "nextthing,gr8",
 NULL,
};

static int __init sunxi_mbus_init(void)
{
 if (!of_device_compatible_match(of_root, sunxi_mbus_platforms))
  return 0;

 bus_register_notifier(&platform_bus_type, &sunxi_mbus_nb);
 return 0;
}
arch_initcall(sunxi_mbus_init);