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
devm_apple_sart_get(struct device * dev)167 struct apple_sart *devm_apple_sart_get(struct device *dev)
168 {
169 struct device_node *sart_node;
170 struct platform_device *sart_pdev;
171 struct apple_sart *sart;
172 int ret;
173
174 sart_node = of_parse_phandle(dev->of_node, "apple,sart", 0);
175 if (!sart_node)
176 return ERR_PTR(-ENODEV);
177
178 sart_pdev = of_find_device_by_node(sart_node);
179 of_node_put(sart_node);
180
181 if (!sart_pdev)
182 return ERR_PTR(-ENODEV);
183
184 sart = dev_get_drvdata(&sart_pdev->dev);
185 if (!sart) {
186 put_device(&sart_pdev->dev);
187 return ERR_PTR(-EPROBE_DEFER);
188 }
189
190 ret = devm_add_action_or_reset(dev, (void (*)(void *))put_device,
191 &sart_pdev->dev);
192 if (ret)
193 return ERR_PTR(ret);
194
195 device_link_add(dev, &sart_pdev->dev,
196 DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
197
198 return sart;
199 }
200 EXPORT_SYMBOL_GPL(devm_apple_sart_get);
201
sart_set_entry(struct apple_sart * sart,int index,u8 flags,phys_addr_t paddr,size_t size)202 static int sart_set_entry(struct apple_sart *sart, int index, u8 flags,
203 phys_addr_t paddr, size_t size)
204 {
205 if (size & ((1 << sart->ops->size_shift) - 1))
206 return -EINVAL;
207 if (paddr & ((1 << sart->ops->paddr_shift) - 1))
208 return -EINVAL;
209
210 paddr >>= sart->ops->size_shift;
211 size >>= sart->ops->paddr_shift;
212
213 if (size > sart->ops->size_max)
214 return -EINVAL;
215
216 sart->ops->set_entry(sart, index, flags, paddr, size);
217 return 0;
218 }
219
apple_sart_add_allowed_region(struct apple_sart * sart,phys_addr_t paddr,size_t size)220 int apple_sart_add_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
221 size_t size)
222 {
223 int i, ret;
224
225 for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
226 if (test_bit(i, &sart->protected_entries))
227 continue;
228 if (test_and_set_bit(i, &sart->used_entries))
229 continue;
230
231 ret = sart_set_entry(sart, i, APPLE_SART_FLAGS_ALLOW, paddr,
232 size);
233 if (ret) {
234 dev_dbg(sart->dev,
235 "unable to set entry %d to [%pa, 0x%zx]\n",
236 i, &paddr, size);
237 clear_bit(i, &sart->used_entries);
238 return ret;
239 }
240
241 dev_dbg(sart->dev, "wrote [%pa, 0x%zx] to %d\n", &paddr, size,
242 i);
243 return 0;
244 }
245
246 dev_warn(sart->dev,
247 "no free entries left to add [paddr: 0x%pa, size: 0x%zx]\n",
248 &paddr, size);
249
250 return -EBUSY;
251 }
252 EXPORT_SYMBOL_GPL(apple_sart_add_allowed_region);
253
apple_sart_remove_allowed_region(struct apple_sart * sart,phys_addr_t paddr,size_t size)254 int apple_sart_remove_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
255 size_t size)
256 {
257 int i;
258
259 dev_dbg(sart->dev,
260 "will remove [paddr: %pa, size: 0x%zx] from allowed regions\n",
261 &paddr, size);
262
263 for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
264 u8 eflags;
265 size_t esize;
266 phys_addr_t epaddr;
267
268 if (test_bit(i, &sart->protected_entries))
269 continue;
270
271 sart->ops->get_entry(sart, i, &eflags, &epaddr, &esize);
272
273 if (epaddr != paddr || esize != size)
274 continue;
275
276 sart->ops->set_entry(sart, i, 0, 0, 0);
277
278 clear_bit(i, &sart->used_entries);
279 dev_dbg(sart->dev, "cleared entry %d\n", i);
280 return 0;
281 }
282
283 dev_warn(sart->dev, "entry [paddr: 0x%pa, size: 0x%zx] not found\n",
284 &paddr, size);
285
286 return -EINVAL;
287 }
288 EXPORT_SYMBOL_GPL(apple_sart_remove_allowed_region);
289
apple_sart_shutdown(struct platform_device * pdev)290 static void apple_sart_shutdown(struct platform_device *pdev)
291 {
292 struct apple_sart *sart = dev_get_drvdata(&pdev->dev);
293 int i;
294
295 for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
296 if (test_bit(i, &sart->protected_entries))
297 continue;
298
299 sart->ops->set_entry(sart, i, 0, 0, 0);
300 }
301 }
302
303 static const struct of_device_id apple_sart_of_match[] = {
304 {
305 .compatible = "apple,t6000-sart",
306 .data = &sart_ops_v3,
307 },
308 {
309 .compatible = "apple,t8103-sart",
310 .data = &sart_ops_v2,
311 },
312 {}
313 };
314 MODULE_DEVICE_TABLE(of, apple_sart_of_match);
315
316 static struct platform_driver apple_sart_driver = {
317 .driver = {
318 .name = "apple-sart",
319 .of_match_table = apple_sart_of_match,
320 },
321 .probe = apple_sart_probe,
322 .shutdown = apple_sart_shutdown,
323 };
324 module_platform_driver(apple_sart_driver);
325
326 MODULE_LICENSE("Dual MIT/GPL");
327 MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
328 MODULE_DESCRIPTION("Apple SART driver");
329
