diff options
Diffstat (limited to 'drivers/soc/apple/sart.c')
| -rw-r--r-- | drivers/soc/apple/sart.c | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/drivers/soc/apple/sart.c b/drivers/soc/apple/sart.c new file mode 100644 index 000000000..afa111736 --- /dev/null +++ b/drivers/soc/apple/sart.c @@ -0,0 +1,333 @@ +// 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"); |