// 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 <[email protected]>");
MODULE_DESCRIPTION("Apple SART driver");
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