sart.c

  1// SPDX-License-Identifier: GPL-2.0-only OR MIT
  2/*
  3 * Apple SART device driver
  4 * Copyright (C) The Asahi Linux Contributors
  5 *
  6 * Apple SART is a simple address filter for some DMA transactions.
  7 * Regions of physical memory must be added to the SART's allow
  8 * list before any DMA can target these. Unlike a proper
  9 * IOMMU no remapping can be done and special support in the
 10 * consumer driver is required since not all DMA transactions of
 11 * a single device are subject to SART filtering.
 12 */
 13
 14#include <linux/soc/apple/sart.h>
 15#include <linux/atomic.h>
 16#include <linux/bits.h>
 17#include <linux/bitfield.h>
 18#include <linux/device.h>
 19#include <linux/io.h>
 20#include <linux/module.h>
 21#include <linux/of.h>
 22#include <linux/of_platform.h>
 23#include <linux/platform_device.h>
 24#include <linux/types.h>
 25
 26#define APPLE_SART_MAX_ENTRIES 16
 27
 28/* SARTv0 registers */
 29#define APPLE_SART0_CONFIG(idx)       (0x00 + 4 * (idx))
 30#define APPLE_SART0_CONFIG_FLAGS      GENMASK(28, 24)
 31#define APPLE_SART0_CONFIG_SIZE       GENMASK(18, 0)
 32#define APPLE_SART0_CONFIG_SIZE_SHIFT 12
 33#define APPLE_SART0_CONFIG_SIZE_MAX   GENMASK(18, 0)
 34
 35#define APPLE_SART0_PADDR(idx)  (0x40 + 4 * (idx))
 36#define APPLE_SART0_PADDR_SHIFT 12
 37
 38#define APPLE_SART0_FLAGS_ALLOW 0xf
 39
 40/* SARTv2 registers */
 41#define APPLE_SART2_CONFIG(idx)	      (0x00 + 4 * (idx))
 42#define APPLE_SART2_CONFIG_FLAGS      GENMASK(31, 24)
 43#define APPLE_SART2_CONFIG_SIZE	      GENMASK(23, 0)
 44#define APPLE_SART2_CONFIG_SIZE_SHIFT 12
 45#define APPLE_SART2_CONFIG_SIZE_MAX   GENMASK(23, 0)
 46
 47#define APPLE_SART2_PADDR(idx)	(0x40 + 4 * (idx))
 48#define APPLE_SART2_PADDR_SHIFT 12
 49
 50#define APPLE_SART2_FLAGS_ALLOW 0xff
 51
 52/* SARTv3 registers */
 53#define APPLE_SART3_CONFIG(idx) (0x00 + 4 * (idx))
 54
 55#define APPLE_SART3_PADDR(idx)	(0x40 + 4 * (idx))
 56#define APPLE_SART3_PADDR_SHIFT 12
 57
 58#define APPLE_SART3_SIZE(idx)  (0x80 + 4 * (idx))
 59#define APPLE_SART3_SIZE_SHIFT 12
 60#define APPLE_SART3_SIZE_MAX   GENMASK(29, 0)
 61
 62#define APPLE_SART3_FLAGS_ALLOW 0xff
 63
 64struct apple_sart_ops {
 65	void (*get_entry)(struct apple_sart *sart, int index, u8 *flags,
 66			  phys_addr_t *paddr, size_t *size);
 67	void (*set_entry)(struct apple_sart *sart, int index, u8 flags,
 68			  phys_addr_t paddr_shifted, size_t size_shifted);
 69	/* This is probably a bitfield but the exact meaning of each bit is unknown. */
 70	unsigned int flags_allow;
 71	unsigned int size_shift;
 72	unsigned int paddr_shift;
 73	size_t size_max;
 74};
 75
 76struct apple_sart {
 77	struct device *dev;
 78	void __iomem *regs;
 79
 80	const struct apple_sart_ops *ops;
 81
 82	unsigned long protected_entries;
 83	unsigned long used_entries;
 84};
 85
 86static void sart0_get_entry(struct apple_sart *sart, int index, u8 *flags,
 87	phys_addr_t *paddr, size_t *size)
 88{
 89	u32 cfg = readl(sart->regs + APPLE_SART0_CONFIG(index));
 90	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART0_PADDR(index));
 91	size_t size_ = FIELD_GET(APPLE_SART0_CONFIG_SIZE, cfg);
 92
 93	*flags = FIELD_GET(APPLE_SART0_CONFIG_FLAGS, cfg);
 94	*size = size_ << APPLE_SART0_CONFIG_SIZE_SHIFT;
 95	*paddr = paddr_ << APPLE_SART0_PADDR_SHIFT;
 96}
 97
 98static void sart0_set_entry(struct apple_sart *sart, int index, u8 flags,
 99	phys_addr_t paddr_shifted, size_t size_shifted)
100{
101	u32 cfg;
102
103	cfg = FIELD_PREP(APPLE_SART0_CONFIG_FLAGS, flags);
104	cfg |= FIELD_PREP(APPLE_SART0_CONFIG_SIZE, size_shifted);
105
106	writel(paddr_shifted, sart->regs + APPLE_SART0_PADDR(index));
107	writel(cfg, sart->regs + APPLE_SART0_CONFIG(index));
108}
109
110static struct apple_sart_ops sart_ops_v0 = {
111	.get_entry = sart0_get_entry,
112	.set_entry = sart0_set_entry,
113	.flags_allow = APPLE_SART0_FLAGS_ALLOW,
114	.size_shift = APPLE_SART0_CONFIG_SIZE_SHIFT,
115	.paddr_shift = APPLE_SART0_PADDR_SHIFT,
116	.size_max = APPLE_SART0_CONFIG_SIZE_MAX,
117};
118
119static void sart2_get_entry(struct apple_sart *sart, int index, u8 *flags,
120			    phys_addr_t *paddr, size_t *size)
121{
122	u32 cfg = readl(sart->regs + APPLE_SART2_CONFIG(index));
123	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART2_PADDR(index));
124	size_t size_ = FIELD_GET(APPLE_SART2_CONFIG_SIZE, cfg);
125
126	*flags = FIELD_GET(APPLE_SART2_CONFIG_FLAGS, cfg);
127	*size = size_ << APPLE_SART2_CONFIG_SIZE_SHIFT;
128	*paddr = paddr_ << APPLE_SART2_PADDR_SHIFT;
129}
130
131static void sart2_set_entry(struct apple_sart *sart, int index, u8 flags,
132			    phys_addr_t paddr_shifted, size_t size_shifted)
133{
134	u32 cfg;
135
136	cfg = FIELD_PREP(APPLE_SART2_CONFIG_FLAGS, flags);
137	cfg |= FIELD_PREP(APPLE_SART2_CONFIG_SIZE, size_shifted);
138
139	writel(paddr_shifted, sart->regs + APPLE_SART2_PADDR(index));
140	writel(cfg, sart->regs + APPLE_SART2_CONFIG(index));
141}
142
143static struct apple_sart_ops sart_ops_v2 = {
144	.get_entry = sart2_get_entry,
145	.set_entry = sart2_set_entry,
146	.flags_allow = APPLE_SART2_FLAGS_ALLOW,
147	.size_shift = APPLE_SART2_CONFIG_SIZE_SHIFT,
148	.paddr_shift = APPLE_SART2_PADDR_SHIFT,
149	.size_max = APPLE_SART2_CONFIG_SIZE_MAX,
150};
151
152static void sart3_get_entry(struct apple_sart *sart, int index, u8 *flags,
153			    phys_addr_t *paddr, size_t *size)
154{
155	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART3_PADDR(index));
156	size_t size_ = readl(sart->regs + APPLE_SART3_SIZE(index));
157
158	*flags = readl(sart->regs + APPLE_SART3_CONFIG(index));
159	*size = size_ << APPLE_SART3_SIZE_SHIFT;
160	*paddr = paddr_ << APPLE_SART3_PADDR_SHIFT;
161}
162
163static void sart3_set_entry(struct apple_sart *sart, int index, u8 flags,
164			    phys_addr_t paddr_shifted, size_t size_shifted)
165{
166	writel(paddr_shifted, sart->regs + APPLE_SART3_PADDR(index));
167	writel(size_shifted, sart->regs + APPLE_SART3_SIZE(index));
168	writel(flags, sart->regs + APPLE_SART3_CONFIG(index));
169}
170
171static struct apple_sart_ops sart_ops_v3 = {
172	.get_entry = sart3_get_entry,
173	.set_entry = sart3_set_entry,
174	.flags_allow = APPLE_SART3_FLAGS_ALLOW,
175	.size_shift = APPLE_SART3_SIZE_SHIFT,
176	.paddr_shift = APPLE_SART3_PADDR_SHIFT,
177	.size_max = APPLE_SART3_SIZE_MAX,
178};
179
180static int apple_sart_probe(struct platform_device *pdev)
181{
182	int i;
183	struct apple_sart *sart;
184	struct device *dev = &pdev->dev;
185
186	sart = devm_kzalloc(dev, sizeof(*sart), GFP_KERNEL);
187	if (!sart)
188		return -ENOMEM;
189
190	sart->dev = dev;
191	sart->ops = of_device_get_match_data(dev);
192
193	sart->regs = devm_platform_ioremap_resource(pdev, 0);
194	if (IS_ERR(sart->regs))
195		return PTR_ERR(sart->regs);
196
197	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
198		u8 flags;
199		size_t size;
200		phys_addr_t paddr;
201
202		sart->ops->get_entry(sart, i, &flags, &paddr, &size);
203
204		if (!flags)
205			continue;
206
207		dev_dbg(sart->dev,
208			"SART bootloader entry: index %02d; flags: 0x%02x; paddr: %pa; size: 0x%zx\n",
209			i, flags, &paddr, size);
210		set_bit(i, &sart->protected_entries);
211	}
212
213	platform_set_drvdata(pdev, sart);
214	return 0;
215}
216
217struct apple_sart *devm_apple_sart_get(struct device *dev)
218{
219	struct device_node *sart_node;
220	struct platform_device *sart_pdev;
221	struct apple_sart *sart;
222
223	sart_node = of_parse_phandle(dev->of_node, "apple,sart", 0);
224	if (!sart_node)
225		return ERR_PTR(-ENODEV);
226
227	sart_pdev = of_find_device_by_node(sart_node);
228	of_node_put(sart_node);
229
230	if (!sart_pdev)
231		return ERR_PTR(-ENODEV);
232
233	sart = dev_get_drvdata(&sart_pdev->dev);
234	if (!sart) {
235		put_device(&sart_pdev->dev);
236		return ERR_PTR(-EPROBE_DEFER);
237	}
238
239	device_link_add(dev, &sart_pdev->dev,
240			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
241
242	put_device(&sart_pdev->dev);
243
244	return sart;
245}
246EXPORT_SYMBOL_GPL(devm_apple_sart_get);
247
248static int sart_set_entry(struct apple_sart *sart, int index, u8 flags,
249			  phys_addr_t paddr, size_t size)
250{
251	if (size & ((1 << sart->ops->size_shift) - 1))
252		return -EINVAL;
253	if (paddr & ((1 << sart->ops->paddr_shift) - 1))
254		return -EINVAL;
255
256	paddr >>= sart->ops->size_shift;
257	size >>= sart->ops->paddr_shift;
258
259	if (size > sart->ops->size_max)
260		return -EINVAL;
261
262	sart->ops->set_entry(sart, index, flags, paddr, size);
263	return 0;
264}
265
266int apple_sart_add_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
267				  size_t size)
268{
269	int i, ret;
270
271	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
272		if (test_bit(i, &sart->protected_entries))
273			continue;
274		if (test_and_set_bit(i, &sart->used_entries))
275			continue;
276
277		ret = sart_set_entry(sart, i, sart->ops->flags_allow, paddr,
278				     size);
279		if (ret) {
280			dev_dbg(sart->dev,
281				"unable to set entry %d to [%pa, 0x%zx]\n",
282				i, &paddr, size);
283			clear_bit(i, &sart->used_entries);
284			return ret;
285		}
286
287		dev_dbg(sart->dev, "wrote [%pa, 0x%zx] to %d\n", &paddr, size,
288			i);
289		return 0;
290	}
291
292	dev_warn(sart->dev,
293		 "no free entries left to add [paddr: 0x%pa, size: 0x%zx]\n",
294		 &paddr, size);
295
296	return -EBUSY;
297}
298EXPORT_SYMBOL_GPL(apple_sart_add_allowed_region);
299
300int apple_sart_remove_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
301				     size_t size)
302{
303	int i;
304
305	dev_dbg(sart->dev,
306		"will remove [paddr: %pa, size: 0x%zx] from allowed regions\n",
307		&paddr, size);
308
309	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
310		u8 eflags;
311		size_t esize;
312		phys_addr_t epaddr;
313
314		if (test_bit(i, &sart->protected_entries))
315			continue;
316
317		sart->ops->get_entry(sart, i, &eflags, &epaddr, &esize);
318
319		if (epaddr != paddr || esize != size)
320			continue;
321
322		sart->ops->set_entry(sart, i, 0, 0, 0);
323
324		clear_bit(i, &sart->used_entries);
325		dev_dbg(sart->dev, "cleared entry %d\n", i);
326		return 0;
327	}
328
329	dev_warn(sart->dev, "entry [paddr: 0x%pa, size: 0x%zx] not found\n",
330		 &paddr, size);
331
332	return -EINVAL;
333}
334EXPORT_SYMBOL_GPL(apple_sart_remove_allowed_region);
335
336static void apple_sart_shutdown(struct platform_device *pdev)
337{
338	struct apple_sart *sart = dev_get_drvdata(&pdev->dev);
339	int i;
340
341	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
342		if (test_bit(i, &sart->protected_entries))
343			continue;
344
345		sart->ops->set_entry(sart, i, 0, 0, 0);
346	}
347}
348
349static const struct of_device_id apple_sart_of_match[] = {
350	{
351		.compatible = "apple,t6000-sart",
352		.data = &sart_ops_v3,
353	},
354	{
355		.compatible = "apple,t8103-sart",
356		.data = &sart_ops_v2,
357	},
358	{
359		.compatible = "apple,t8015-sart",
360		.data = &sart_ops_v0,
361	},
362	{}
363};
364MODULE_DEVICE_TABLE(of, apple_sart_of_match);
365
366static struct platform_driver apple_sart_driver = {
367	.driver = {
368		.name = "apple-sart",
369		.of_match_table = apple_sart_of_match,
370	},
371	.probe = apple_sart_probe,
372	.shutdown = apple_sart_shutdown,
373};
374module_platform_driver(apple_sart_driver);
375
376MODULE_LICENSE("Dual MIT/GPL");
377MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
378MODULE_DESCRIPTION("Apple SART driver");