xref: /openbmc/linux/drivers/soc/apple/sart.c (revision 422d0b86)
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 /* This is probably a bitfield but the exact meaning of each bit is unknown. */
29 #define APPLE_SART_FLAGS_ALLOW 0xff
30 
31 /* SARTv2 registers */
32 #define APPLE_SART2_CONFIG(idx)	      (0x00 + 4 * (idx))
33 #define APPLE_SART2_CONFIG_FLAGS      GENMASK(31, 24)
34 #define APPLE_SART2_CONFIG_SIZE	      GENMASK(23, 0)
35 #define APPLE_SART2_CONFIG_SIZE_SHIFT 12
36 #define APPLE_SART2_CONFIG_SIZE_MAX   GENMASK(23, 0)
37 
38 #define APPLE_SART2_PADDR(idx)	(0x40 + 4 * (idx))
39 #define APPLE_SART2_PADDR_SHIFT 12
40 
41 /* SARTv3 registers */
42 #define APPLE_SART3_CONFIG(idx) (0x00 + 4 * (idx))
43 
44 #define APPLE_SART3_PADDR(idx)	(0x40 + 4 * (idx))
45 #define APPLE_SART3_PADDR_SHIFT 12
46 
47 #define APPLE_SART3_SIZE(idx)  (0x80 + 4 * (idx))
48 #define APPLE_SART3_SIZE_SHIFT 12
49 #define APPLE_SART3_SIZE_MAX   GENMASK(29, 0)
50 
51 struct apple_sart_ops {
52 	void (*get_entry)(struct apple_sart *sart, int index, u8 *flags,
53 			  phys_addr_t *paddr, size_t *size);
54 	void (*set_entry)(struct apple_sart *sart, int index, u8 flags,
55 			  phys_addr_t paddr_shifted, size_t size_shifted);
56 	unsigned int size_shift;
57 	unsigned int paddr_shift;
58 	size_t size_max;
59 };
60 
61 struct apple_sart {
62 	struct device *dev;
63 	void __iomem *regs;
64 
65 	const struct apple_sart_ops *ops;
66 
67 	unsigned long protected_entries;
68 	unsigned long used_entries;
69 };
70 
sart2_get_entry(struct apple_sart * sart,int index,u8 * flags,phys_addr_t * paddr,size_t * size)71 static void sart2_get_entry(struct apple_sart *sart, int index, u8 *flags,
72 			    phys_addr_t *paddr, size_t *size)
73 {
74 	u32 cfg = readl(sart->regs + APPLE_SART2_CONFIG(index));
75 	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART2_PADDR(index));
76 	size_t size_ = FIELD_GET(APPLE_SART2_CONFIG_SIZE, cfg);
77 
78 	*flags = FIELD_GET(APPLE_SART2_CONFIG_FLAGS, cfg);
79 	*size = size_ << APPLE_SART2_CONFIG_SIZE_SHIFT;
80 	*paddr = paddr_ << APPLE_SART2_PADDR_SHIFT;
81 }
82 
sart2_set_entry(struct apple_sart * sart,int index,u8 flags,phys_addr_t paddr_shifted,size_t size_shifted)83 static void sart2_set_entry(struct apple_sart *sart, int index, u8 flags,
84 			    phys_addr_t paddr_shifted, size_t size_shifted)
85 {
86 	u32 cfg;
87 
88 	cfg = FIELD_PREP(APPLE_SART2_CONFIG_FLAGS, flags);
89 	cfg |= FIELD_PREP(APPLE_SART2_CONFIG_SIZE, size_shifted);
90 
91 	writel(paddr_shifted, sart->regs + APPLE_SART2_PADDR(index));
92 	writel(cfg, sart->regs + APPLE_SART2_CONFIG(index));
93 }
94 
95 static struct apple_sart_ops sart_ops_v2 = {
96 	.get_entry = sart2_get_entry,
97 	.set_entry = sart2_set_entry,
98 	.size_shift = APPLE_SART2_CONFIG_SIZE_SHIFT,
99 	.paddr_shift = APPLE_SART2_PADDR_SHIFT,
100 	.size_max = APPLE_SART2_CONFIG_SIZE_MAX,
101 };
102 
sart3_get_entry(struct apple_sart * sart,int index,u8 * flags,phys_addr_t * paddr,size_t * size)103 static void sart3_get_entry(struct apple_sart *sart, int index, u8 *flags,
104 			    phys_addr_t *paddr, size_t *size)
105 {
106 	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART3_PADDR(index));
107 	size_t size_ = readl(sart->regs + APPLE_SART3_SIZE(index));
108 
109 	*flags = readl(sart->regs + APPLE_SART3_CONFIG(index));
110 	*size = size_ << APPLE_SART3_SIZE_SHIFT;
111 	*paddr = paddr_ << APPLE_SART3_PADDR_SHIFT;
112 }
113 
sart3_set_entry(struct apple_sart * sart,int index,u8 flags,phys_addr_t paddr_shifted,size_t size_shifted)114 static void sart3_set_entry(struct apple_sart *sart, int index, u8 flags,
115 			    phys_addr_t paddr_shifted, size_t size_shifted)
116 {
117 	writel(paddr_shifted, sart->regs + APPLE_SART3_PADDR(index));
118 	writel(size_shifted, sart->regs + APPLE_SART3_SIZE(index));
119 	writel(flags, sart->regs + APPLE_SART3_CONFIG(index));
120 }
121 
122 static struct apple_sart_ops sart_ops_v3 = {
123 	.get_entry = sart3_get_entry,
124 	.set_entry = sart3_set_entry,
125 	.size_shift = APPLE_SART3_SIZE_SHIFT,
126 	.paddr_shift = APPLE_SART3_PADDR_SHIFT,
127 	.size_max = APPLE_SART3_SIZE_MAX,
128 };
129 
apple_sart_probe(struct platform_device * pdev)130 static int apple_sart_probe(struct platform_device *pdev)
131 {
132 	int i;
133 	struct apple_sart *sart;
134 	struct device *dev = &pdev->dev;
135 
136 	sart = devm_kzalloc(dev, sizeof(*sart), GFP_KERNEL);
137 	if (!sart)
138 		return -ENOMEM;
139 
140 	sart->dev = dev;
141 	sart->ops = of_device_get_match_data(dev);
142 
143 	sart->regs = devm_platform_ioremap_resource(pdev, 0);
144 	if (IS_ERR(sart->regs))
145 		return PTR_ERR(sart->regs);
146 
147 	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
148 		u8 flags;
149 		size_t size;
150 		phys_addr_t paddr;
151 
152 		sart->ops->get_entry(sart, i, &flags, &paddr, &size);
153 
154 		if (!flags)
155 			continue;
156 
157 		dev_dbg(sart->dev,
158 			"SART bootloader entry: index %02d; flags: 0x%02x; paddr: %pa; size: 0x%zx\n",
159 			i, flags, &paddr, size);
160 		set_bit(i, &sart->protected_entries);
161 	}
162 
163 	platform_set_drvdata(pdev, sart);
164 	return 0;
165 }
166 
apple_sart_put_device(void * dev)167 static void apple_sart_put_device(void *dev)
168 {
169 	put_device(dev);
170 }
171 
devm_apple_sart_get(struct device * dev)172 struct apple_sart *devm_apple_sart_get(struct device *dev)
173 {
174 	struct device_node *sart_node;
175 	struct platform_device *sart_pdev;
176 	struct apple_sart *sart;
177 	int ret;
178 
179 	sart_node = of_parse_phandle(dev->of_node, "apple,sart", 0);
180 	if (!sart_node)
181 		return ERR_PTR(-ENODEV);
182 
183 	sart_pdev = of_find_device_by_node(sart_node);
184 	of_node_put(sart_node);
185 
186 	if (!sart_pdev)
187 		return ERR_PTR(-ENODEV);
188 
189 	sart = dev_get_drvdata(&sart_pdev->dev);
190 	if (!sart) {
191 		put_device(&sart_pdev->dev);
192 		return ERR_PTR(-EPROBE_DEFER);
193 	}
194 
195 	ret = devm_add_action_or_reset(dev, apple_sart_put_device,
196 				       &sart_pdev->dev);
197 	if (ret)
198 		return ERR_PTR(ret);
199 
200 	device_link_add(dev, &sart_pdev->dev,
201 			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
202 
203 	return sart;
204 }
205 EXPORT_SYMBOL_GPL(devm_apple_sart_get);
206 
sart_set_entry(struct apple_sart * sart,int index,u8 flags,phys_addr_t paddr,size_t size)207 static int sart_set_entry(struct apple_sart *sart, int index, u8 flags,
208 			  phys_addr_t paddr, size_t size)
209 {
210 	if (size & ((1 << sart->ops->size_shift) - 1))
211 		return -EINVAL;
212 	if (paddr & ((1 << sart->ops->paddr_shift) - 1))
213 		return -EINVAL;
214 
215 	paddr >>= sart->ops->size_shift;
216 	size >>= sart->ops->paddr_shift;
217 
218 	if (size > sart->ops->size_max)
219 		return -EINVAL;
220 
221 	sart->ops->set_entry(sart, index, flags, paddr, size);
222 	return 0;
223 }
224 
apple_sart_add_allowed_region(struct apple_sart * sart,phys_addr_t paddr,size_t size)225 int apple_sart_add_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
226 				  size_t size)
227 {
228 	int i, ret;
229 
230 	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
231 		if (test_bit(i, &sart->protected_entries))
232 			continue;
233 		if (test_and_set_bit(i, &sart->used_entries))
234 			continue;
235 
236 		ret = sart_set_entry(sart, i, APPLE_SART_FLAGS_ALLOW, paddr,
237 				     size);
238 		if (ret) {
239 			dev_dbg(sart->dev,
240 				"unable to set entry %d to [%pa, 0x%zx]\n",
241 				i, &paddr, size);
242 			clear_bit(i, &sart->used_entries);
243 			return ret;
244 		}
245 
246 		dev_dbg(sart->dev, "wrote [%pa, 0x%zx] to %d\n", &paddr, size,
247 			i);
248 		return 0;
249 	}
250 
251 	dev_warn(sart->dev,
252 		 "no free entries left to add [paddr: 0x%pa, size: 0x%zx]\n",
253 		 &paddr, size);
254 
255 	return -EBUSY;
256 }
257 EXPORT_SYMBOL_GPL(apple_sart_add_allowed_region);
258 
apple_sart_remove_allowed_region(struct apple_sart * sart,phys_addr_t paddr,size_t size)259 int apple_sart_remove_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
260 				     size_t size)
261 {
262 	int i;
263 
264 	dev_dbg(sart->dev,
265 		"will remove [paddr: %pa, size: 0x%zx] from allowed regions\n",
266 		&paddr, size);
267 
268 	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
269 		u8 eflags;
270 		size_t esize;
271 		phys_addr_t epaddr;
272 
273 		if (test_bit(i, &sart->protected_entries))
274 			continue;
275 
276 		sart->ops->get_entry(sart, i, &eflags, &epaddr, &esize);
277 
278 		if (epaddr != paddr || esize != size)
279 			continue;
280 
281 		sart->ops->set_entry(sart, i, 0, 0, 0);
282 
283 		clear_bit(i, &sart->used_entries);
284 		dev_dbg(sart->dev, "cleared entry %d\n", i);
285 		return 0;
286 	}
287 
288 	dev_warn(sart->dev, "entry [paddr: 0x%pa, size: 0x%zx] not found\n",
289 		 &paddr, size);
290 
291 	return -EINVAL;
292 }
293 EXPORT_SYMBOL_GPL(apple_sart_remove_allowed_region);
294 
apple_sart_shutdown(struct platform_device * pdev)295 static void apple_sart_shutdown(struct platform_device *pdev)
296 {
297 	struct apple_sart *sart = dev_get_drvdata(&pdev->dev);
298 	int i;
299 
300 	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
301 		if (test_bit(i, &sart->protected_entries))
302 			continue;
303 
304 		sart->ops->set_entry(sart, i, 0, 0, 0);
305 	}
306 }
307 
308 static const struct of_device_id apple_sart_of_match[] = {
309 	{
310 		.compatible = "apple,t6000-sart",
311 		.data = &sart_ops_v3,
312 	},
313 	{
314 		.compatible = "apple,t8103-sart",
315 		.data = &sart_ops_v2,
316 	},
317 	{}
318 };
319 MODULE_DEVICE_TABLE(of, apple_sart_of_match);
320 
321 static struct platform_driver apple_sart_driver = {
322 	.driver = {
323 		.name = "apple-sart",
324 		.of_match_table = apple_sart_of_match,
325 	},
326 	.probe = apple_sart_probe,
327 	.shutdown = apple_sart_shutdown,
328 };
329 module_platform_driver(apple_sart_driver);
330 
331 MODULE_LICENSE("Dual MIT/GPL");
332 MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
333 MODULE_DESCRIPTION("Apple SART driver");
334