drivers/soc/apple/sart.c - linux - Git at Google

 // 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/device.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);
 	void (*set_entry)(struct apple_sart *sart, int index, u8 flags,
 			  phys_addr_t paddr_shifted, size_t size_shifted);
 	unsigned int size_shift;
 	unsigned int paddr_shift;
 	size_t size_max;
 };

 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(sart->regs + APPLE_SART2_CONFIG(index));
 	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART2_PADDR(index));
 	size_t size_ = FIELD_GET(APPLE_SART2_CONFIG_SIZE, cfg);

 	*flags = FIELD_GET(APPLE_SART2_CONFIG_FLAGS, cfg);
 	*size = size_ << APPLE_SART2_CONFIG_SIZE_SHIFT;
 	*paddr = paddr_ << APPLE_SART2_PADDR_SHIFT;
 }

 static void sart2_set_entry(struct apple_sart *sart, int index, u8 flags,
 			    phys_addr_t paddr_shifted, size_t size_shifted)
 {
 	u32 cfg;

 	cfg = FIELD_PREP(APPLE_SART2_CONFIG_FLAGS, flags);
 	cfg |= FIELD_PREP(APPLE_SART2_CONFIG_SIZE, size_shifted);

 	writel(paddr_shifted, sart->regs + APPLE_SART2_PADDR(index));
 	writel(cfg, sart->regs + APPLE_SART2_CONFIG(index));
 }

 static struct apple_sart_ops sart_ops_v2 = {
 	.get_entry = sart2_get_entry,
 	.set_entry = sart2_set_entry,
 	.size_shift = APPLE_SART2_CONFIG_SIZE_SHIFT,
 	.paddr_shift = APPLE_SART2_PADDR_SHIFT,
 	.size_max = APPLE_SART2_CONFIG_SIZE_MAX,
 };

 static void sart3_get_entry(struct apple_sart *sart, int index, u8 *flags,
 			    phys_addr_t *paddr, size_t *size)
 {
 	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART3_PADDR(index));
 	size_t size_ = readl(sart->regs + APPLE_SART3_SIZE(index));

 	*flags = readl(sart->regs + APPLE_SART3_CONFIG(index));
 	*size = size_ << APPLE_SART3_SIZE_SHIFT;
 	*paddr = paddr_ << APPLE_SART3_PADDR_SHIFT;
 }

 static void sart3_set_entry(struct apple_sart *sart, int index, u8 flags,
 			    phys_addr_t paddr_shifted, size_t size_shifted)
 {
 	writel(paddr_shifted, sart->regs + APPLE_SART3_PADDR(index));
 	writel(size_shifted, sart->regs + APPLE_SART3_SIZE(index));
 	writel(flags, sart->regs + APPLE_SART3_CONFIG(index));
 }

 static struct apple_sart_ops sart_ops_v3 = {
 	.get_entry = sart3_get_entry,
 	.set_entry = sart3_set_entry,
 	.size_shift = APPLE_SART3_SIZE_SHIFT,
 	.paddr_shift = APPLE_SART3_PADDR_SHIFT,
 	.size_max = APPLE_SART3_SIZE_MAX,
 };

 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;
 }

 static void apple_sart_put_device(void *dev)
 {
 	put_device(dev);
 }

 struct apple_sart *devm_apple_sart_get(struct device *dev)
 {
 	struct device_node *sart_node;
 	struct platform_device *sart_pdev;
 	struct apple_sart *sart;
 	int ret;

 	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) {
 		put_device(&sart_pdev->dev);
 		return ERR_PTR(-EPROBE_DEFER);
 	}

 	ret = devm_add_action_or_reset(dev, apple_sart_put_device,
 				       &sart_pdev->dev);
 	if (ret)
 		return ERR_PTR(ret);

 	device_link_add(dev, &sart_pdev->dev,
 			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);

 	return sart;
 }
 EXPORT_SYMBOL_GPL(devm_apple_sart_get);

 static int sart_set_entry(struct apple_sart *sart, int index, u8 flags,
 			  phys_addr_t paddr, size_t size)
 {
 	if (size & ((1 << sart->ops->size_shift) - 1))
 		return -EINVAL;
 	if (paddr & ((1 << sart->ops->paddr_shift) - 1))
 		return -EINVAL;

 	paddr >>= sart->ops->size_shift;
 	size >>= sart->ops->paddr_shift;

 	if (size > sart->ops->size_max)
 		return -EINVAL;

 	sart->ops->set_entry(sart, index, flags, paddr, size);
 	return 0;
 }

 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_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%pa, size: 0x%zx]\n",
 		 &paddr, size);

 	return -EBUSY;
 }
 EXPORT_SYMBOL_GPL(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%pa, size: 0x%zx] not found\n",
 		 &paddr, size);

 	return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(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@svenpeter.dev>");
 MODULE_DESCRIPTION("Apple SART driver");
	// 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/device.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);
	void (set_entry)(struct apple_sart sart, int index, u8 flags,
	phys_addr_t paddr_shifted, size_t size_shifted);
	unsigned int size_shift;
	unsigned int paddr_shift;
	size_t size_max;
	};

	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(sart->regs + APPLE_SART2_CONFIG(index));
	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART2_PADDR(index));
	size_t size_ = FIELD_GET(APPLE_SART2_CONFIG_SIZE, cfg);

	*flags = FIELD_GET(APPLE_SART2_CONFIG_FLAGS, cfg);
	*size = size_ << APPLE_SART2_CONFIG_SIZE_SHIFT;
	*paddr = paddr_ << APPLE_SART2_PADDR_SHIFT;
	}

	static void sart2_set_entry(struct apple_sart *sart, int index, u8 flags,
	phys_addr_t paddr_shifted, size_t size_shifted)
	{
	u32 cfg;

	cfg = FIELD_PREP(APPLE_SART2_CONFIG_FLAGS, flags);
	cfg \|= FIELD_PREP(APPLE_SART2_CONFIG_SIZE, size_shifted);

	writel(paddr_shifted, sart->regs + APPLE_SART2_PADDR(index));
	writel(cfg, sart->regs + APPLE_SART2_CONFIG(index));
	}

	static struct apple_sart_ops sart_ops_v2 = {
	.get_entry = sart2_get_entry,
	.set_entry = sart2_set_entry,
	.size_shift = APPLE_SART2_CONFIG_SIZE_SHIFT,
	.paddr_shift = APPLE_SART2_PADDR_SHIFT,
	.size_max = APPLE_SART2_CONFIG_SIZE_MAX,
	};

	static void sart3_get_entry(struct apple_sart sart, int index, u8 flags,
	phys_addr_t paddr, size_t size)
	{
	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART3_PADDR(index));
	size_t size_ = readl(sart->regs + APPLE_SART3_SIZE(index));

	*flags = readl(sart->regs + APPLE_SART3_CONFIG(index));
	*size = size_ << APPLE_SART3_SIZE_SHIFT;
	*paddr = paddr_ << APPLE_SART3_PADDR_SHIFT;
	}

	static void sart3_set_entry(struct apple_sart *sart, int index, u8 flags,
	phys_addr_t paddr_shifted, size_t size_shifted)
	{
	writel(paddr_shifted, sart->regs + APPLE_SART3_PADDR(index));
	writel(size_shifted, sart->regs + APPLE_SART3_SIZE(index));
	writel(flags, sart->regs + APPLE_SART3_CONFIG(index));
	}

	static struct apple_sart_ops sart_ops_v3 = {
	.get_entry = sart3_get_entry,
	.set_entry = sart3_set_entry,
	.size_shift = APPLE_SART3_SIZE_SHIFT,
	.paddr_shift = APPLE_SART3_PADDR_SHIFT,
	.size_max = APPLE_SART3_SIZE_MAX,
	};

	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;
	}

	static void apple_sart_put_device(void *dev)
	{
	put_device(dev);
	}

	struct apple_sart devm_apple_sart_get(struct device dev)
	{
	struct device_node *sart_node;
	struct platform_device *sart_pdev;
	struct apple_sart *sart;
	int ret;

	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) {
	put_device(&sart_pdev->dev);
	return ERR_PTR(-EPROBE_DEFER);
	}

	ret = devm_add_action_or_reset(dev, apple_sart_put_device,
	&sart_pdev->dev);
	if (ret)
	return ERR_PTR(ret);

	device_link_add(dev, &sart_pdev->dev,
	DL_FLAG_PM_RUNTIME \| DL_FLAG_AUTOREMOVE_SUPPLIER);

	return sart;
	}
	EXPORT_SYMBOL_GPL(devm_apple_sart_get);

	static int sart_set_entry(struct apple_sart *sart, int index, u8 flags,
	phys_addr_t paddr, size_t size)
	{
	if (size & ((1 << sart->ops->size_shift) - 1))
	return -EINVAL;
	if (paddr & ((1 << sart->ops->paddr_shift) - 1))
	return -EINVAL;

	paddr >>= sart->ops->size_shift;
	size >>= sart->ops->paddr_shift;

	if (size > sart->ops->size_max)
	return -EINVAL;

	sart->ops->set_entry(sart, index, flags, paddr, size);
	return 0;
	}

	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_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%pa, size: 0x%zx]\n",
	&paddr, size);

	return -EBUSY;
	}
	EXPORT_SYMBOL_GPL(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%pa, size: 0x%zx] not found\n",
	&paddr, size);

	return -EINVAL;
	}
	EXPORT_SYMBOL_GPL(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@svenpeter.dev>");
	MODULE_DESCRIPTION("Apple SART driver");