The NVMe co-processor on the Apple M1 uses a DMA address filter called
SART for some DMA transactions. This adds a simple driver used to
configure the memory regions from which DMA transactions are allowed.
Co-developed-by: Hector Martin <marcan@xxxxxxxxx>
Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
Signed-off-by: Sven Peter <sven@xxxxxxxxxxxxx>
---
MAINTAINERS | 1 +
drivers/soc/apple/Kconfig | 11 ++
drivers/soc/apple/Makefile | 3 +
drivers/soc/apple/sart.c | 318 +++++++++++++++++++++++++++++++++
include/linux/soc/apple/sart.h | 77 ++++++++
5 files changed, 410 insertions(+)
create mode 100644 drivers/soc/apple/sart.c
create mode 100644 include/linux/soc/apple/sart.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 027c3b4ad61c..3d37fe7a0408 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1787,6 +1787,7 @@ F: drivers/watchdog/apple_wdt.c
F: include/dt-bindings/interrupt-controller/apple-aic.h
F: include/dt-bindings/pinctrl/apple.h
F: include/linux/apple-mailbox.h
+F: include/linux/soc/apple/*
ARM/ARTPEC MACHINE SUPPORT
M: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
diff --git a/drivers/soc/apple/Kconfig b/drivers/soc/apple/Kconfig
index 9b8de31d6a8f..8c37ffd53fbd 100644
--- a/drivers/soc/apple/Kconfig
+++ b/drivers/soc/apple/Kconfig
@@ -17,6 +17,17 @@ config APPLE_PMGR_PWRSTATE
controls for SoC devices. This driver manages them through the
generic power domain framework, and also provides reset support.
+config APPLE_SART
+ tristate "Apple SART DMA address filter"
+ depends on ARCH_APPLE || COMPILE_TEST
+ default ARCH_APPLE
+ help
+ Apple SART is a simple DMA address filter used on Apple SoCs such
+ as the M1. It is usually required for the NVMe coprocessor which does
+ not use a proper IOMMU.
+
+ Say 'y' here if you have an Apple SoC.
+
endmenu
endif
diff --git a/drivers/soc/apple/Makefile b/drivers/soc/apple/Makefile
index c114e84667e4..c83c66317098 100644
--- a/drivers/soc/apple/Makefile
+++ b/drivers/soc/apple/Makefile
@@ -1,2 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_APPLE_PMGR_PWRSTATE) += apple-pmgr-pwrstate.o
+
+obj-$(CONFIG_APPLE_SART) += apple-sart.o
+apple-sart-y = sart.o
diff --git a/drivers/soc/apple/sart.c b/drivers/soc/apple/sart.c
new file mode 100644
index 000000000000..836ea68db2fc
--- /dev/null
+++ b/drivers/soc/apple/sart.c
@@ -0,0 +1,318 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SART device driver
+ * Copyright (C) The Asahi Linux Contributors
+ *
+ * Apple SART is a simple address filter for some DMA transactions.
+ * Regions of physical memory must be added to the SART's allow
+ * list before any DMA can target these. Unlike a proper
+ * IOMMU no remapping can be done and special support in the
+ * consumer driver is required since not all DMA transactions of
+ * a single device are subject to SART filtering.
+ */
+
+#include <linux/soc/apple/sart.h>
+#include <linux/atomic.h>
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#define APPLE_SART_MAX_ENTRIES 16
+
+/* This is probably a bitfield but the exact meaning of each bit is unknown. */
+#define APPLE_SART_FLAGS_ALLOW 0xff
+
+/* SARTv2 registers */
+#define APPLE_SART2_CONFIG(idx) (0x00 + 4 * (idx))
+#define APPLE_SART2_CONFIG_FLAGS GENMASK(31, 24)
+#define APPLE_SART2_CONFIG_SIZE GENMASK(23, 0)
+#define APPLE_SART2_CONFIG_SIZE_SHIFT 12
+#define APPLE_SART2_CONFIG_SIZE_MAX GENMASK(23, 0)
+
+#define APPLE_SART2_PADDR(idx) (0x40 + 4 * (idx))
+#define APPLE_SART2_PADDR_SHIFT 12
+
+/* SARTv3 registers */
+#define APPLE_SART3_CONFIG(idx) (0x00 + 4 * (idx))
+
+#define APPLE_SART3_PADDR(idx) (0x40 + 4 * (idx))
+#define APPLE_SART3_PADDR_SHIFT 12
+
+#define APPLE_SART3_SIZE(idx) (0x80 + 4 * (idx))
+#define APPLE_SART3_SIZE_SHIFT 12
+#define APPLE_SART3_SIZE_MAX GENMASK(29, 0)
+
+struct apple_sart_ops {
+ void (*get_entry)(struct apple_sart *sart, int index, u8 *flags,
+ phys_addr_t *paddr, size_t *size);
+ int (*set_entry)(struct apple_sart *sart, int index, u8 flags,
+ phys_addr_t paddr, size_t size);
+};
+
+struct apple_sart {
+ struct device *dev;
+ void __iomem *regs;
+
+ const struct apple_sart_ops *ops;
+
+ unsigned long protected_entries;
+ unsigned long used_entries;
+};
+
+static void sart2_get_entry(struct apple_sart *sart, int index, u8 *flags,
+ phys_addr_t *paddr, size_t *size)
+{
+ u32 cfg = readl_relaxed(sart->regs + APPLE_SART2_CONFIG(index));
+ u32 paddr_ = readl_relaxed(sart->regs + APPLE_SART2_PADDR(index));
+ u32 size_ = FIELD_GET(APPLE_SART2_CONFIG_SIZE, cfg);
+
+ *flags = FIELD_GET(APPLE_SART2_CONFIG_FLAGS, cfg);
+ *size = (size_t)size_ << APPLE_SART2_CONFIG_SIZE_SHIFT;
+ *paddr = (phys_addr_t)paddr_ << APPLE_SART2_PADDR_SHIFT;
+}
+
+static int sart2_set_entry(struct apple_sart *sart, int index, u8 flags,
+ phys_addr_t paddr, size_t size)
+{
+ u32 cfg;
+
+ if (size & ((1 << APPLE_SART2_CONFIG_SIZE_SHIFT) - 1))
+ return -EINVAL;
+ if (paddr & ((1 << APPLE_SART2_PADDR_SHIFT) - 1))
+ return -EINVAL;
+
+ size >>= APPLE_SART2_CONFIG_SIZE_SHIFT;
+ paddr >>= APPLE_SART2_PADDR_SHIFT;
+
+ if (size > APPLE_SART2_CONFIG_SIZE_MAX)
+ return -EINVAL;
+
+ cfg = FIELD_PREP(APPLE_SART2_CONFIG_FLAGS, flags);
+ cfg |= FIELD_PREP(APPLE_SART2_CONFIG_SIZE, size);
+
+ writel_relaxed(paddr, sart->regs + APPLE_SART2_PADDR(index));
+ writel_relaxed(cfg, sart->regs + APPLE_SART2_CONFIG(index));
+
+ return 0;
+}
+
+static struct apple_sart_ops sart_ops_v2 = {
+ .get_entry = sart2_get_entry,
+ .set_entry = sart2_set_entry,
+};
+
+static void sart3_get_entry(struct apple_sart *sart, int index, u8 *flags,
+ phys_addr_t *paddr, size_t *size)
+{
+ u32 paddr_ = readl_relaxed(sart->regs + APPLE_SART3_PADDR(index));
+ u32 size_ = readl_relaxed(sart->regs + APPLE_SART3_SIZE(index));
+
+ *flags = readl_relaxed(sart->regs + APPLE_SART3_CONFIG(index));
+ *size = (size_t)size_ << APPLE_SART3_SIZE_SHIFT;
+ *paddr = (phys_addr_t)paddr_ << APPLE_SART3_PADDR_SHIFT;
+}
+
+static int sart3_set_entry(struct apple_sart *sart, int index, u8 flags,
+ phys_addr_t paddr, size_t size)
+{
+ if (size & ((1 << APPLE_SART3_SIZE_SHIFT) - 1))
+ return -EINVAL;
+ if (paddr & ((1 << APPLE_SART3_PADDR_SHIFT) - 1))
+ return -EINVAL;
+
+ paddr >>= APPLE_SART3_PADDR_SHIFT;
+ size >>= APPLE_SART3_SIZE_SHIFT;
+
+ if (size > APPLE_SART3_SIZE_MAX)
+ return -EINVAL;
+
+ writel_relaxed(paddr, sart->regs + APPLE_SART3_PADDR(index));
+ writel_relaxed(size, sart->regs + APPLE_SART3_SIZE(index));
+ writel_relaxed(flags, sart->regs + APPLE_SART3_CONFIG(index));
+
+ return 0;
+}
+
+static struct apple_sart_ops sart_ops_v3 = {
+ .get_entry = sart3_get_entry,
+ .set_entry = sart3_set_entry,
+};
+
+static int apple_sart_probe(struct platform_device *pdev)
+{
+ int i;
+ struct apple_sart *sart;
+ struct device *dev = &pdev->dev;
+
+ sart = devm_kzalloc(dev, sizeof(*sart), GFP_KERNEL);
+ if (!sart)
+ return -ENOMEM;
+
+ sart->dev = dev;
+ sart->ops = of_device_get_match_data(dev);
+
+ sart->regs = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(sart->regs))
+ return PTR_ERR(sart->regs);
+
+ for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
+ u8 flags;
+ size_t size;
+ phys_addr_t paddr;
+
+ sart->ops->get_entry(sart, i, &flags, &paddr, &size);
+
+ if (!flags)
+ continue;
+
+ dev_dbg(sart->dev,
+ "SART bootloader entry: index %02d; flags: 0x%02x; paddr: %pa; size: 0x%zx\n",
+ i, flags, &paddr, size);
+ set_bit(i, &sart->protected_entries);
+ }
+
+ platform_set_drvdata(pdev, sart);
+ return 0;
+}
+
+struct apple_sart *apple_sart_get(struct device *dev)
+{
+ struct device_node *sart_node;
+ struct platform_device *sart_pdev;
+ struct apple_sart *sart;
+
+ sart_node = of_parse_phandle(dev->of_node, "apple,sart", 0);
+ if (!sart_node)
+ return ERR_PTR(ENODEV);
+
+ sart_pdev = of_find_device_by_node(sart_node);
+ of_node_put(sart_node);
+
+ if (!sart_pdev)
+ return ERR_PTR(ENODEV);
+
+ sart = dev_get_drvdata(&sart_pdev->dev);
+ if (!sart)
+ return ERR_PTR(EPROBE_DEFER);
+
+ device_link_add(dev, &sart_pdev->dev,
+ DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
+
+ return sart;
+}
+EXPORT_SYMBOL(apple_sart_get);
+
+int apple_sart_add_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
+ size_t size)
+{
+ int i, ret;
+
+ for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
+ if (test_bit(i, &sart->protected_entries))
+ continue;
+ if (test_and_set_bit(i, &sart->used_entries))
+ continue;
+
+ ret = sart->ops->set_entry(sart, i, APPLE_SART_FLAGS_ALLOW,
+ paddr, size);
+ if (ret) {
+ dev_dbg(sart->dev,
+ "unable to set entry %d to [%pa, 0x%zx]\n",
+ i, &paddr, size);
+ clear_bit(i, &sart->used_entries);
+ return ret;
+ }
+
+ dev_dbg(sart->dev, "wrote [%pa, 0x%zx] to %d\n", &paddr, size,
+ i);
+ return 0;
+ }
+
+ dev_warn(sart->dev,
+ "no free entries left to add [paddr: 0x%llx, size: 0x%zx]\n",
+ paddr, size);
+
+ return -EBUSY;
+}
+EXPORT_SYMBOL(apple_sart_add_allowed_region);
+
+int apple_sart_remove_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
+ size_t size)
+{
+ int i;
+
+ dev_dbg(sart->dev,
+ "will remove [paddr: %pa, size: 0x%zx] from allowed regions\n",
+ &paddr, size);
+
+ for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
+ u8 eflags;
+ size_t esize;
+ phys_addr_t epaddr;
+
+ if (test_bit(i, &sart->protected_entries))
+ continue;
+
+ sart->ops->get_entry(sart, i, &eflags, &epaddr, &esize);
+
+ if (epaddr != paddr || esize != size)
+ continue;
+
+ sart->ops->set_entry(sart, i, 0, 0, 0);
+
+ clear_bit(i, &sart->used_entries);
+ dev_dbg(sart->dev, "cleared entry %d\n", i);
+ return 0;
+ }
+
+ dev_warn(sart->dev, "entry [paddr: 0x%llx, size: 0x%zx] not found\n",
+ paddr, size);
+
+ return -EINVAL;
+}
+EXPORT_SYMBOL(apple_sart_remove_allowed_region);
+
+static void apple_sart_shutdown(struct platform_device *pdev)
+{
+ struct apple_sart *sart = dev_get_drvdata(&pdev->dev);
+ int i;
+
+ for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
+ if (test_bit(i, &sart->protected_entries))
+ continue;
+
+ sart->ops->set_entry(sart, i, 0, 0, 0);
+ }
+}
+
+static const struct of_device_id apple_sart_of_match[] = {
+ {
+ .compatible = "apple,t6000-sart",
+ .data = &sart_ops_v3,
+ },
+ {
+ .compatible = "apple,t8103-sart",
+ .data = &sart_ops_v2,
+ },
+ {}
+};
+MODULE_DEVICE_TABLE(of, apple_sart_of_match);
+
+static struct platform_driver apple_sart_driver = {
+ .driver = {
+ .name = "apple-sart",
+ .of_match_table = apple_sart_of_match,
+ },
+ .probe = apple_sart_probe,
+ .shutdown = apple_sart_shutdown,
+};
+module_platform_driver(apple_sart_driver);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_AUTHOR("Sven Peter <sven@xxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Apple SART driver");
diff --git a/include/linux/soc/apple/sart.h b/include/linux/soc/apple/sart.h
new file mode 100644
index 000000000000..4e3d4960be5a
--- /dev/null
+++ b/include/linux/soc/apple/sart.h
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+/*
+ * Apple SART device driver
+ * Copyright (C) The Asahi Linux Contributors
+ *
+ * Apple SART is a simple address filter for DMA transactions.
+ * Regions of physical memory must be added to the SART's allow
+ * list before any DMA can target these. Unlike a proper
+ * IOMMU no remapping can be done.
+ */
+
+#ifndef _LINUX_SOC_APPLE_SART_H_
+#define _LINUX_SOC_APPLE_SART_H_
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/types.h>
+
+struct apple_sart;
+
+#if IS_ENABLED(CONFIG_APPLE_SART)
+
+/*
+ * Get a reference to the SART attached to dev.
+ *
+ * Looks for the phandle reference in apple,sart and returns a pointer
+ * to the corresponding apple_sart struct to be used with
+ * apple_sart_add_allowed_region and apple_sart_remove_allowed_region.
+ */
+struct apple_sart *apple_sart_get(struct device *dev);
+
+/*
+ * Adds the region [paddr, paddr+size] to the DMA allow list.
+ *
+ * @sart: SART reference
+ * @paddr: Start address of the region to be used for DMA
+ * @size: Size of the region to be used for DMA.
+ */
+int apple_sart_add_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
+ size_t size);
+
+/*
+ * Removes the region [paddr, paddr+size] from the DMA allow list.
+ *
+ * Note that exact same paddr and size used for apple_sart_add_allowed_region
+ * have to be passed.
+ *
+ * @sart: SART reference
+ * @paddr: Start address of the region no longer used for DMA
+ * @size: Size of the region no longer used for DMA.
+ */
+int apple_sart_remove_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
+ size_t size);
+
+#else
+
+static inline struct apple_sart *apple_sart_get(struct device *dev)
+{
+ return ERR_PTR(-ENODEV);
+}
+
+static inline int apple_sart_add_allowed_region(struct apple_sart *sart,
+ phys_addr_t paddr, size_t size)
+{
+ return -ENODEV;
+}
+
+static inline int apple_sart_remove_allowed_region(struct apple_sart *sart,
+ phys_addr_t paddr,
+ size_t size)
+{
+ return -ENODEV;
+}
+
+#endif /* IS_ENABLED(CONFIG_APPLE_SART) */
+
+#endif /* _LINUX_SOC_APPLE_SART_H_ */
--
2.25.1
