arm64: Use bus notifiers to set per-device coherent DMA ops

Recently, the default DMA ops have been changed to non-coherent for
alignment with 32-bit ARM platforms (and DT files). This patch adds bus
notifiers to be able to set the coherent DMA ops (with no cache
maintenance) for devices explicitly marked as coherent via the
"dma-coherent" DT property.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 93e7df8968fe123d40ce7ad2a017ac88aef7e118..7ec784653b29fad2b1eba1c49a21e9e499a6c167 100644 (file)
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -396,7 +396,7 @@ static int __init arm64_device_init(void)
        of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
        return 0;
 }
-arch_initcall(arm64_device_init);
+arch_initcall_sync(arm64_device_init);
 
 static DEFINE_PER_CPU(struct cpu, cpu_data);
 

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 1f65963a9c0464c5e3233a165957e6788a39da86..c851eb44dc505f8b250b7e1205b1a5ccb35afc8c 100644 (file)
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -22,8 +22,11 @@
 #include <linux/slab.h>
 #include <linux/dma-mapping.h>
 #include <linux/dma-contiguous.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
 #include <linux/vmalloc.h>
 #include <linux/swiotlb.h>
+#include <linux/amba/bus.h>
 
 #include <asm/cacheflush.h>
 
@@ -305,17 +308,45 @@ struct dma_map_ops coherent_swiotlb_dma_ops = {
 };
 EXPORT_SYMBOL(coherent_swiotlb_dma_ops);
 
+static int dma_bus_notifier(struct notifier_block *nb,
+                           unsigned long event, void *_dev)
+{
+       struct device *dev = _dev;
+
+       if (event != BUS_NOTIFY_ADD_DEVICE)
+               return NOTIFY_DONE;
+
+       if (of_property_read_bool(dev->of_node, "dma-coherent"))
+               set_dma_ops(dev, &coherent_swiotlb_dma_ops);
+
+       return NOTIFY_OK;
+}
+
+static struct notifier_block platform_bus_nb = {
+       .notifier_call = dma_bus_notifier,
+};
+
+static struct notifier_block amba_bus_nb = {
+       .notifier_call = dma_bus_notifier,
+};
+
 extern int swiotlb_late_init_with_default_size(size_t default_size);
 
 static int __init swiotlb_late_init(void)
 {
        size_t swiotlb_size = min(SZ_64M, MAX_ORDER_NR_PAGES << PAGE_SHIFT);
 
+       /*
+        * These must be registered before of_platform_populate().
+        */
+       bus_register_notifier(&platform_bus_type, &platform_bus_nb);
+       bus_register_notifier(&amba_bustype, &amba_bus_nb);
+
        dma_ops = &noncoherent_swiotlb_dma_ops;
 
        return swiotlb_late_init_with_default_size(swiotlb_size);
 }
-subsys_initcall(swiotlb_late_init);
+arch_initcall(swiotlb_late_init);
 
 #define PREALLOC_DMA_DEBUG_ENTRIES     4096