@@ -906,6 +906,7 @@ config ARCH_APPLE
select DM_SERIAL
select DM_USB
select DM_VIDEO
+ select IOMMU
select LINUX_KERNEL_IMAGE_HEADER
select OF_CONTROL
select OF_BOARD
@@ -10,4 +10,14 @@ config IOMMU
help
Enable driver model for IOMMU devices.
+config APPLE_DART
+ bool "Apple DART support"
+ depends on IOMMU && ARCH_APPLE
+ default y
+ help
+ Enable support for the DART on Apple SoCs. The DART is Apple's
+ IOMMU implementation. The driver performs the necessary
+ configuration to put the DART into bypass mode such that it can
+ be used transparently by U-Boot.
+
endmenu
@@ -2,4 +2,5 @@
obj-$(CONFIG_IOMMU) += iommu-uclass.o
+obj-$(CONFIG_APPLE_DART) += apple_dart.o
obj-$(CONFIG_SANDBOX) += sandbox_iommu.o
new file mode 100644
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
+ */
+
+#include <common.h>
+#include <cpu_func.h>
+#include <dm.h>
+#include <asm/io.h>
+
+#define DART_PARAMS2 0x0004
+#define DART_PARAMS2_BYPASS_SUPPORT BIT(0)
+#define DART_TLB_OP 0x0020
+#define DART_TLB_OP_OPMASK (0xfff << 20)
+#define DART_TLB_OP_FLUSH (0x001 << 20)
+#define DART_TLB_OP_BUSY BIT(2)
+#define DART_TLB_OP_SIDMASK 0x0034
+#define DART_ERROR_STATUS 0x0040
+#define DART_TCR(sid) (0x0100 + 4 * (sid))
+#define DART_TCR_TRANSLATE_ENABLE BIT(7)
+#define DART_TCR_BYPASS_DART BIT(8)
+#define DART_TCR_BYPASS_DAPF BIT(12)
+#define DART_TTBR(sid, idx) (0x0200 + 16 * (sid) + 4 * (idx))
+#define DART_TTBR_VALID BIT(31)
+#define DART_TTBR_SHIFT 12
+
+static int apple_dart_probe(struct udevice *dev)
+{
+ void *base;
+ int sid, i;
+
+ base = dev_read_addr_ptr(dev);
+ if (!base)
+ return -EINVAL;
+
+ u32 params2 = readl(base + DART_PARAMS2);
+ if (params2 & DART_PARAMS2_BYPASS_SUPPORT) {
+ for (sid = 0; sid < 16; sid++) {
+ writel(DART_TCR_BYPASS_DART | DART_TCR_BYPASS_DAPF,
+ base + DART_TCR(sid));
+ for (i = 0; i < 4; i++)
+ writel(0, base + DART_TTBR(sid, i));
+ }
+ }
+
+ return 0;
+}
+
+static const struct udevice_id apple_dart_ids[] = {
+ { .compatible = "apple,t8103-dart" },
+ { /* sentinel */ }
+};
+
+U_BOOT_DRIVER(apple_dart) = {
+ .name = "apple_dart",
+ .id = UCLASS_IOMMU,
+ .of_match = apple_dart_ids,
+ .probe = apple_dart_probe
+};
The DART is an IOMMU that is used on Apple's M1 SoC. This driver configures the DART such that it operates in bypass mode which is enough to support DMA for the USB3 ports integrated on the SoC. Signed-off-by: Mark Kettenis <kettenis@openbsd.org> --- arch/arm/Kconfig | 1 + drivers/iommu/Kconfig | 10 +++++++ drivers/iommu/Makefile | 1 + drivers/iommu/apple_dart.c | 59 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 71 insertions(+) create mode 100644 drivers/iommu/apple_dart.c