334 lines
8.5 KiB
C
334 lines
8.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only OR MIT
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/*
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* Apple SART device driver
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* Copyright (C) The Asahi Linux Contributors
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*
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* Apple SART is a simple address filter for some DMA transactions.
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* Regions of physical memory must be added to the SART's allow
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* list before any DMA can target these. Unlike a proper
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* IOMMU no remapping can be done and special support in the
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* consumer driver is required since not all DMA transactions of
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* a single device are subject to SART filtering.
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*/
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#include <linux/soc/apple/sart.h>
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#include <linux/atomic.h>
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#include <linux/bits.h>
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#include <linux/bitfield.h>
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#include <linux/device.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_platform.h>
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#include <linux/platform_device.h>
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#include <linux/types.h>
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#define APPLE_SART_MAX_ENTRIES 16
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/* This is probably a bitfield but the exact meaning of each bit is unknown. */
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#define APPLE_SART_FLAGS_ALLOW 0xff
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/* SARTv2 registers */
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#define APPLE_SART2_CONFIG(idx) (0x00 + 4 * (idx))
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#define APPLE_SART2_CONFIG_FLAGS GENMASK(31, 24)
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#define APPLE_SART2_CONFIG_SIZE GENMASK(23, 0)
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#define APPLE_SART2_CONFIG_SIZE_SHIFT 12
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#define APPLE_SART2_CONFIG_SIZE_MAX GENMASK(23, 0)
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#define APPLE_SART2_PADDR(idx) (0x40 + 4 * (idx))
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#define APPLE_SART2_PADDR_SHIFT 12
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/* SARTv3 registers */
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#define APPLE_SART3_CONFIG(idx) (0x00 + 4 * (idx))
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#define APPLE_SART3_PADDR(idx) (0x40 + 4 * (idx))
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#define APPLE_SART3_PADDR_SHIFT 12
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#define APPLE_SART3_SIZE(idx) (0x80 + 4 * (idx))
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#define APPLE_SART3_SIZE_SHIFT 12
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#define APPLE_SART3_SIZE_MAX GENMASK(29, 0)
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struct apple_sart_ops {
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void (*get_entry)(struct apple_sart *sart, int index, u8 *flags,
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phys_addr_t *paddr, size_t *size);
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void (*set_entry)(struct apple_sart *sart, int index, u8 flags,
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phys_addr_t paddr_shifted, size_t size_shifted);
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unsigned int size_shift;
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unsigned int paddr_shift;
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size_t size_max;
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};
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struct apple_sart {
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struct device *dev;
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void __iomem *regs;
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const struct apple_sart_ops *ops;
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unsigned long protected_entries;
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unsigned long used_entries;
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};
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static void sart2_get_entry(struct apple_sart *sart, int index, u8 *flags,
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phys_addr_t *paddr, size_t *size)
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{
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u32 cfg = readl(sart->regs + APPLE_SART2_CONFIG(index));
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phys_addr_t paddr_ = readl(sart->regs + APPLE_SART2_PADDR(index));
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size_t size_ = FIELD_GET(APPLE_SART2_CONFIG_SIZE, cfg);
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*flags = FIELD_GET(APPLE_SART2_CONFIG_FLAGS, cfg);
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*size = size_ << APPLE_SART2_CONFIG_SIZE_SHIFT;
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*paddr = paddr_ << APPLE_SART2_PADDR_SHIFT;
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}
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static void sart2_set_entry(struct apple_sart *sart, int index, u8 flags,
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phys_addr_t paddr_shifted, size_t size_shifted)
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{
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u32 cfg;
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cfg = FIELD_PREP(APPLE_SART2_CONFIG_FLAGS, flags);
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cfg |= FIELD_PREP(APPLE_SART2_CONFIG_SIZE, size_shifted);
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writel(paddr_shifted, sart->regs + APPLE_SART2_PADDR(index));
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writel(cfg, sart->regs + APPLE_SART2_CONFIG(index));
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}
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static struct apple_sart_ops sart_ops_v2 = {
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.get_entry = sart2_get_entry,
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.set_entry = sart2_set_entry,
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.size_shift = APPLE_SART2_CONFIG_SIZE_SHIFT,
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.paddr_shift = APPLE_SART2_PADDR_SHIFT,
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.size_max = APPLE_SART2_CONFIG_SIZE_MAX,
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};
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static void sart3_get_entry(struct apple_sart *sart, int index, u8 *flags,
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phys_addr_t *paddr, size_t *size)
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{
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phys_addr_t paddr_ = readl(sart->regs + APPLE_SART3_PADDR(index));
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size_t size_ = readl(sart->regs + APPLE_SART3_SIZE(index));
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*flags = readl(sart->regs + APPLE_SART3_CONFIG(index));
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*size = size_ << APPLE_SART3_SIZE_SHIFT;
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*paddr = paddr_ << APPLE_SART3_PADDR_SHIFT;
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}
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static void sart3_set_entry(struct apple_sart *sart, int index, u8 flags,
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phys_addr_t paddr_shifted, size_t size_shifted)
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{
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writel(paddr_shifted, sart->regs + APPLE_SART3_PADDR(index));
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writel(size_shifted, sart->regs + APPLE_SART3_SIZE(index));
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writel(flags, sart->regs + APPLE_SART3_CONFIG(index));
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}
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static struct apple_sart_ops sart_ops_v3 = {
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.get_entry = sart3_get_entry,
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.set_entry = sart3_set_entry,
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.size_shift = APPLE_SART3_SIZE_SHIFT,
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.paddr_shift = APPLE_SART3_PADDR_SHIFT,
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.size_max = APPLE_SART3_SIZE_MAX,
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};
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static int apple_sart_probe(struct platform_device *pdev)
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{
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int i;
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struct apple_sart *sart;
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struct device *dev = &pdev->dev;
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sart = devm_kzalloc(dev, sizeof(*sart), GFP_KERNEL);
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if (!sart)
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return -ENOMEM;
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sart->dev = dev;
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sart->ops = of_device_get_match_data(dev);
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sart->regs = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(sart->regs))
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return PTR_ERR(sart->regs);
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for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
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u8 flags;
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size_t size;
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phys_addr_t paddr;
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sart->ops->get_entry(sart, i, &flags, &paddr, &size);
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if (!flags)
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continue;
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dev_dbg(sart->dev,
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"SART bootloader entry: index %02d; flags: 0x%02x; paddr: %pa; size: 0x%zx\n",
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i, flags, &paddr, size);
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set_bit(i, &sart->protected_entries);
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}
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platform_set_drvdata(pdev, sart);
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return 0;
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}
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static void apple_sart_put_device(void *dev)
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{
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put_device(dev);
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}
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struct apple_sart *devm_apple_sart_get(struct device *dev)
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{
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struct device_node *sart_node;
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struct platform_device *sart_pdev;
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struct apple_sart *sart;
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int ret;
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sart_node = of_parse_phandle(dev->of_node, "apple,sart", 0);
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if (!sart_node)
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return ERR_PTR(-ENODEV);
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sart_pdev = of_find_device_by_node(sart_node);
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of_node_put(sart_node);
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if (!sart_pdev)
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return ERR_PTR(-ENODEV);
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sart = dev_get_drvdata(&sart_pdev->dev);
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if (!sart) {
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put_device(&sart_pdev->dev);
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return ERR_PTR(-EPROBE_DEFER);
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}
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ret = devm_add_action_or_reset(dev, apple_sart_put_device,
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&sart_pdev->dev);
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if (ret)
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return ERR_PTR(ret);
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device_link_add(dev, &sart_pdev->dev,
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DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
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return sart;
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}
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EXPORT_SYMBOL_GPL(devm_apple_sart_get);
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static int sart_set_entry(struct apple_sart *sart, int index, u8 flags,
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phys_addr_t paddr, size_t size)
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{
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if (size & ((1 << sart->ops->size_shift) - 1))
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return -EINVAL;
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if (paddr & ((1 << sart->ops->paddr_shift) - 1))
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return -EINVAL;
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paddr >>= sart->ops->size_shift;
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size >>= sart->ops->paddr_shift;
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if (size > sart->ops->size_max)
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return -EINVAL;
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sart->ops->set_entry(sart, index, flags, paddr, size);
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return 0;
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}
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int apple_sart_add_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
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size_t size)
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{
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int i, ret;
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for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
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if (test_bit(i, &sart->protected_entries))
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continue;
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if (test_and_set_bit(i, &sart->used_entries))
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continue;
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ret = sart_set_entry(sart, i, APPLE_SART_FLAGS_ALLOW, paddr,
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size);
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if (ret) {
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dev_dbg(sart->dev,
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"unable to set entry %d to [%pa, 0x%zx]\n",
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i, &paddr, size);
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clear_bit(i, &sart->used_entries);
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return ret;
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}
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dev_dbg(sart->dev, "wrote [%pa, 0x%zx] to %d\n", &paddr, size,
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i);
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return 0;
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}
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dev_warn(sart->dev,
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"no free entries left to add [paddr: 0x%pa, size: 0x%zx]\n",
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&paddr, size);
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return -EBUSY;
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}
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EXPORT_SYMBOL_GPL(apple_sart_add_allowed_region);
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int apple_sart_remove_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
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size_t size)
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{
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int i;
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dev_dbg(sart->dev,
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"will remove [paddr: %pa, size: 0x%zx] from allowed regions\n",
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&paddr, size);
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for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
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u8 eflags;
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size_t esize;
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phys_addr_t epaddr;
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if (test_bit(i, &sart->protected_entries))
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continue;
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sart->ops->get_entry(sart, i, &eflags, &epaddr, &esize);
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if (epaddr != paddr || esize != size)
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continue;
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sart->ops->set_entry(sart, i, 0, 0, 0);
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clear_bit(i, &sart->used_entries);
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dev_dbg(sart->dev, "cleared entry %d\n", i);
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return 0;
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}
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dev_warn(sart->dev, "entry [paddr: 0x%pa, size: 0x%zx] not found\n",
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&paddr, size);
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return -EINVAL;
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}
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EXPORT_SYMBOL_GPL(apple_sart_remove_allowed_region);
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static void apple_sart_shutdown(struct platform_device *pdev)
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{
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struct apple_sart *sart = dev_get_drvdata(&pdev->dev);
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int i;
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for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
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if (test_bit(i, &sart->protected_entries))
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continue;
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sart->ops->set_entry(sart, i, 0, 0, 0);
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}
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}
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static const struct of_device_id apple_sart_of_match[] = {
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{
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.compatible = "apple,t6000-sart",
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.data = &sart_ops_v3,
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},
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{
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.compatible = "apple,t8103-sart",
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.data = &sart_ops_v2,
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},
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{}
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};
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MODULE_DEVICE_TABLE(of, apple_sart_of_match);
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static struct platform_driver apple_sart_driver = {
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.driver = {
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.name = "apple-sart",
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.of_match_table = apple_sart_of_match,
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},
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.probe = apple_sart_probe,
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.shutdown = apple_sart_shutdown,
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};
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module_platform_driver(apple_sart_driver);
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MODULE_LICENSE("Dual MIT/GPL");
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MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
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MODULE_DESCRIPTION("Apple SART driver");
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