From: Simon Glass sjg@chromium.org Date: Sun, 19 Sep 2021 21:16:00 -0600
Hi Mark,
On Sat, 18 Sept 2021 at 07:55, Mark Kettenis kettenis@openbsd.org wrote:
The DART is an IOMMU that is used on Apple's M1 SoC. This driver supports the DART in bypass mode as well as in a mode where it creates a 1:1 mapping of a subset of RAM as not all DARTs support bypass mode. The USB3 ports integrated on the SoC use a DART that supports bypass mode. The 1:1 mapping will be used in the future to support other devices such as the PCIe host bridge of the M1 SoC.
Signed-off-by: Mark Kettenis kettenis@openbsd.org
drivers/misc/Kconfig | 7 ++ drivers/misc/Makefile | 1 + drivers/misc/apple_dart.c | 171 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 179 insertions(+) create mode 100644 drivers/misc/apple_dart.c
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index 997b713221..d70b060e74 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -38,6 +38,13 @@ config ALTERA_SYSID Select this to enable a sysid for Altera devices. Please find details on the "Embedded Peripherals IP User Guide" of Altera.
+config APPLE_DART
bool "Apple DART support"depends on MISC && ARCH_APPLEdefault yhelpEnable support for the DART on Apple SoCs.Should have at least 3 lines. E.g. what does DART stand for, what does it do and what does the driver support?
Sure. The DART is what we usually call an IOMMU.
config ATSHA204A bool "Support for Atmel ATSHA204A module" depends on MISC diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index b64cd2a4de..f666cd392d 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -29,6 +29,7 @@ endif endif obj-$(CONFIG_ALI152X) += ali512x.o obj-$(CONFIG_ALTERA_SYSID) += altera_sysid.o +obj-$(CONFIG_APPLE_DART) += apple_dart.o obj-$(CONFIG_ATSHA204A) += atsha204a-i2c.o obj-$(CONFIG_CBMEM_CONSOLE) += cbmem_console.o obj-$(CONFIG_DS4510) += ds4510.o diff --git a/drivers/misc/apple_dart.c b/drivers/misc/apple_dart.c new file mode 100644 index 0000000000..f619a624d0 --- /dev/null +++ b/drivers/misc/apple_dart.c @@ -0,0 +1,171 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*
- Copyright (C) 2021 Mark Kettenis kettenis@openbsd.org
- */
+#include <common.h> +#include <clk.h> +#include <cpu_func.h> +#include <dm.h> +#include <mapmem.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
+struct apple_dart_priv {
How about s/apple_dart/dart/ ?
It makes the code easier to read.
I think using apple_dart_ consistently as a prefix makes more sense.
struct clk_bulk clks;void *base;+};
+dma_addr_t apple_dart_bus_start; +phys_addr_t apple_dart_phys_start; +phys_size_t apple_dart_size = SZ_512M;
Try to avoid variables in drivers. Can these go in a priv struct?
Not really since the intent is that these variables specify a global "window" that is mapped 1:1 into all the DARTs.
+static void apple_dart_flush_tlb(struct apple_dart_priv *priv)
comments on these functions
+{
u32 status;writel(0xffffffff, priv->base + DART_TLB_OP_SIDMASK);writel(DART_TLB_OP_FLUSH, priv->base + DART_TLB_OP);for (;;) {status = readl(priv->base + DART_TLB_OP);if ((status & DART_TLB_OP_OPMASK) == 0)break;if ((status & DART_TLB_OP_BUSY) == 0)break;}+}
+static int apple_dart_clk_init(struct udevice *dev,
struct apple_dart_priv *priv)+{
int ret;ret = clk_get_bulk(dev, &priv->clks);if (ret == -ENOSYS || ret == -ENOENT)Does -ENOSYS not indicate an error? If it doesn't, I think a comment would help here.
So we just learned that what we previously considered to be clocks are really better modelled as power domains. So this code will go away.
return 0;if (ret)return ret;ret = clk_enable_bulk(&priv->clks);if (ret) {clk_release_bulk(&priv->clks);return ret;}return 0;+}
+static int apple_dart_bind(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));}}Not allowed hardware access in bind(). Can this more to probe() ?
Well, I need to make sure that this happens before other drivers get probed (in particular the xhci-dwc3 driver). Is there a better mechanism to achieve that?
return 0;+}
+static int apple_dart_probe(struct udevice *dev) +{
struct apple_dart_priv *priv = dev_get_priv(dev);phys_addr_t phys;u64 *l1, *l2;int sid, i, j;int ret;apple_dart_phys_start = gd->ram_top - apple_dart_size;priv->base = dev_read_addr_ptr(dev);if (!priv->base)return -EINVAL;ret = apple_dart_clk_init(dev, priv);if (ret)return ret;l1 = memalign(SZ_64K, SZ_64K);memset(l1, 0, SZ_64K);i = 0;phys = apple_dart_phys_start;while (phys < apple_dart_phys_start + apple_dart_size) {l2 = memalign(SZ_16K, SZ_16K);check for error
memset(l2, 0, SZ_16K);for (j = 0; j < 2048; j++) {l2[j] = phys | 0x3;phys += SZ_16K;}flush_dcache_range((unsigned long)l2,(unsigned long)l2 + SZ_16K);l1[i++] = (phys_addr_t)l2 | 0x8 | 0x3;Do you need the cast? What are the magic numbers here? Can you use an enum/#define ?
Not sure if we know the exact meaning of those bits yet. But there is a Linux driver now, so maybe I need to look at it again.
}flush_dcache_range((unsigned long)l1, (unsigned long)l1 + SZ_64K);for (sid = 0; sid < 16; sid++) {comment,...what is this doing?
for (i = 0; i < 4; i++)writel(0, priv->base + DART_TTBR(sid, i));}apple_dart_flush_tlb(priv);for (sid = 0; sid < 16; sid++) {phys = (phys_addr_t)l1;for (i = 0; i < 4; i++) {writel((phys >> DART_TTBR_SHIFT) | DART_TTBR_VALID,priv->base + DART_TTBR(sid, i));phys += SZ_16K;}}apple_dart_flush_tlb(priv);for (sid = 0; sid < 16; sid++)writel(DART_TCR_TRANSLATE_ENABLE, priv->base + DART_TCR(sid));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_MISC,.of_match = apple_dart_ids,.priv_auto = sizeof(struct apple_dart_priv),.bind = apple_dart_bind,.probe = apple_dart_probe+};
2.33.0
Regards, Simon