1 /*
2 * Copyright (c) 2018-2023, ARM Limited and Contributors. All rights reserved.
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 */
6
7 /* Helper functions to offer easier navigation of Device Tree Blob */
8
9 #include <assert.h>
10 #include <errno.h>
11 #include <inttypes.h>
12 #include <stdint.h>
13 #include <string.h>
14
15 #include <libfdt.h>
16
17 #include <common/debug.h>
18 #include <common/fdt_wrappers.h>
19 #include <common/uuid.h>
20
21 /*
22 * Read cells from a given property of the given node. Any number of 32-bit
23 * cells of the property can be read. Returns 0 on success, or a negative
24 * FDT error value otherwise.
25 */
fdt_read_uint32_array(const void * dtb,int node,const char * prop_name,unsigned int cells,uint32_t * value)26 int fdt_read_uint32_array(const void *dtb, int node, const char *prop_name,
27 unsigned int cells, uint32_t *value)
28 {
29 const fdt32_t *prop;
30 int value_len;
31
32 assert(dtb != NULL);
33 assert(prop_name != NULL);
34 assert(value != NULL);
35 assert(node >= 0);
36
37 /* Access property and obtain its length (in bytes) */
38 prop = fdt_getprop(dtb, node, prop_name, &value_len);
39 if (prop == NULL) {
40 VERBOSE("Couldn't find property %s in dtb\n", prop_name);
41 return -FDT_ERR_NOTFOUND;
42 }
43
44 /* Verify that property length can fill the entire array. */
45 if (NCELLS((unsigned int)value_len) < cells) {
46 WARN("Property length mismatch\n");
47 return -FDT_ERR_BADVALUE;
48 }
49
50 for (unsigned int i = 0U; i < cells; i++) {
51 value[i] = fdt32_to_cpu(prop[i]);
52 }
53
54 return 0;
55 }
56
fdt_read_uint32(const void * dtb,int node,const char * prop_name,uint32_t * value)57 int fdt_read_uint32(const void *dtb, int node, const char *prop_name,
58 uint32_t *value)
59 {
60 return fdt_read_uint32_array(dtb, node, prop_name, 1, value);
61 }
62
fdt_read_uint32_default(const void * dtb,int node,const char * prop_name,uint32_t dflt_value)63 uint32_t fdt_read_uint32_default(const void *dtb, int node,
64 const char *prop_name, uint32_t dflt_value)
65 {
66 uint32_t ret = dflt_value;
67 int err = fdt_read_uint32(dtb, node, prop_name, &ret);
68
69 if (err < 0) {
70 return dflt_value;
71 }
72
73 return ret;
74 }
75
fdt_read_uint64(const void * dtb,int node,const char * prop_name,uint64_t * value)76 int fdt_read_uint64(const void *dtb, int node, const char *prop_name,
77 uint64_t *value)
78 {
79 uint32_t array[2] = {0, 0};
80 int ret;
81
82 ret = fdt_read_uint32_array(dtb, node, prop_name, 2, array);
83 if (ret < 0) {
84 return ret;
85 }
86
87 *value = ((uint64_t)array[0] << 32) | array[1];
88 return 0;
89 }
90
91 /*
92 * Read bytes from a given property of the given node. Any number of
93 * bytes of the property can be read. The fdt pointer is updated.
94 * Returns 0 on success, and -1 on error.
95 */
fdtw_read_bytes(const void * dtb,int node,const char * prop,unsigned int length,void * value)96 int fdtw_read_bytes(const void *dtb, int node, const char *prop,
97 unsigned int length, void *value)
98 {
99 const void *ptr;
100 int value_len;
101
102 assert(dtb != NULL);
103 assert(prop != NULL);
104 assert(value != NULL);
105 assert(node >= 0);
106
107 /* Access property and obtain its length (in bytes) */
108 ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop),
109 &value_len);
110 if (ptr == NULL) {
111 WARN("Couldn't find property %s in dtb\n", prop);
112 return -1;
113 }
114
115 /* Verify that property length is not less than number of bytes */
116 if ((unsigned int)value_len < length) {
117 WARN("Property length mismatch\n");
118 return -1;
119 }
120
121 (void)memcpy(value, ptr, length);
122
123 return 0;
124 }
125
126 /*
127 * Read string from a given property of the given node. Up to 'size - 1'
128 * characters are read, and a NUL terminator is added. Returns 0 on success,
129 * and -1 upon error.
130 */
fdtw_read_string(const void * dtb,int node,const char * prop,char * str,size_t size)131 int fdtw_read_string(const void *dtb, int node, const char *prop,
132 char *str, size_t size)
133 {
134 const char *ptr;
135 size_t len;
136
137 assert(dtb != NULL);
138 assert(node >= 0);
139 assert(prop != NULL);
140 assert(str != NULL);
141 assert(size > 0U);
142
143 ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop), NULL);
144 if (ptr == NULL) {
145 WARN("Couldn't find property %s in dtb\n", prop);
146 return -1;
147 }
148
149 len = strlcpy(str, ptr, size);
150 if (len >= size) {
151 WARN("String of property %s in dtb has been truncated\n", prop);
152 return -1;
153 }
154
155 return 0;
156 }
157
158 /*
159 * Read UUID from a given property of the given node. Returns 0 on success,
160 * and a negative value upon error.
161 */
fdtw_read_uuid(const void * dtb,int node,const char * prop,unsigned int length,uint8_t * uuid)162 int fdtw_read_uuid(const void *dtb, int node, const char *prop,
163 unsigned int length, uint8_t *uuid)
164 {
165 /* Buffer for UUID string (plus NUL terminator) */
166 char uuid_string[UUID_STRING_LENGTH + 1U];
167 int err;
168
169 assert(dtb != NULL);
170 assert(prop != NULL);
171 assert(uuid != NULL);
172 assert(node >= 0);
173
174 if (length < UUID_BYTES_LENGTH) {
175 return -EINVAL;
176 }
177
178 err = fdtw_read_string(dtb, node, prop, uuid_string,
179 UUID_STRING_LENGTH + 1U);
180 if (err != 0) {
181 return err;
182 }
183
184 if (read_uuid(uuid, uuid_string) != 0) {
185 return -FDT_ERR_BADVALUE;
186 }
187
188 return 0;
189 }
190
191 /*
192 * Write cells in place to a given property of the given node. At most 2 cells
193 * of the property are written. Returns 0 on success, and -1 upon error.
194 */
fdtw_write_inplace_cells(void * dtb,int node,const char * prop,unsigned int cells,void * value)195 int fdtw_write_inplace_cells(void *dtb, int node, const char *prop,
196 unsigned int cells, void *value)
197 {
198 int err, len;
199
200 assert(dtb != NULL);
201 assert(prop != NULL);
202 assert(value != NULL);
203 assert(node >= 0);
204
205 /* We expect either 1 or 2 cell property */
206 assert(cells <= 2U);
207
208 if (cells == 2U)
209 *(fdt64_t *)value = cpu_to_fdt64(*(uint64_t *)value);
210 else
211 *(fdt32_t *)value = cpu_to_fdt32(*(uint32_t *)value);
212
213 len = (int)cells * 4;
214
215 /* Set property value in place */
216 err = fdt_setprop_inplace(dtb, node, prop, value, len);
217 if (err != 0) {
218 WARN("Modify property %s failed with error %d\n", prop, err);
219 return -1;
220 }
221
222 return 0;
223 }
224
225 /*
226 * Write bytes in place to a given property of the given node.
227 * Any number of bytes of the property can be written.
228 * Returns 0 on success, and < 0 on error.
229 */
fdtw_write_inplace_bytes(void * dtb,int node,const char * prop,unsigned int length,const void * data)230 int fdtw_write_inplace_bytes(void *dtb, int node, const char *prop,
231 unsigned int length, const void *data)
232 {
233 const void *ptr;
234 int namelen, value_len, err;
235
236 assert(dtb != NULL);
237 assert(prop != NULL);
238 assert(data != NULL);
239 assert(node >= 0);
240
241 namelen = (int)strlen(prop);
242
243 /* Access property and obtain its length in bytes */
244 ptr = fdt_getprop_namelen(dtb, node, prop, namelen, &value_len);
245 if (ptr == NULL) {
246 WARN("Couldn't find property %s in dtb\n", prop);
247 return -1;
248 }
249
250 /* Verify that property length is not less than number of bytes */
251 if ((unsigned int)value_len < length) {
252 WARN("Property length mismatch\n");
253 return -1;
254 }
255
256 /* Set property value in place */
257 err = fdt_setprop_inplace_namelen_partial(dtb, node, prop,
258 namelen, 0,
259 data, (int)length);
260 if (err != 0) {
261 WARN("Set property %s failed with error %d\n", prop, err);
262 }
263
264 return err;
265 }
266
fdt_read_prop_cells(const fdt32_t * prop,int nr_cells)267 static uint64_t fdt_read_prop_cells(const fdt32_t *prop, int nr_cells)
268 {
269 uint64_t reg = fdt32_to_cpu(prop[0]);
270
271 if (nr_cells > 1) {
272 reg = (reg << 32) | fdt32_to_cpu(prop[1]);
273 }
274
275 return reg;
276 }
277
fdt_get_reg_props_by_index(const void * dtb,int node,int index,uintptr_t * base,size_t * size)278 int fdt_get_reg_props_by_index(const void *dtb, int node, int index,
279 uintptr_t *base, size_t *size)
280 {
281 const fdt32_t *prop;
282 int parent, len;
283 int ac, sc;
284 int cell;
285
286 parent = fdt_parent_offset(dtb, node);
287 if (parent < 0) {
288 return -FDT_ERR_BADOFFSET;
289 }
290
291 ac = fdt_address_cells(dtb, parent);
292 sc = fdt_size_cells(dtb, parent);
293
294 cell = index * (ac + sc);
295
296 prop = fdt_getprop(dtb, node, "reg", &len);
297 if (prop == NULL) {
298 WARN("Couldn't find \"reg\" property in dtb\n");
299 return -FDT_ERR_NOTFOUND;
300 }
301
302 if (((cell + ac + sc) * (int)sizeof(uint32_t)) > len) {
303 return -FDT_ERR_BADVALUE;
304 }
305
306 if (base != NULL) {
307 *base = (uintptr_t)fdt_read_prop_cells(&prop[cell], ac);
308 }
309
310 if (size != NULL) {
311 *size = (size_t)fdt_read_prop_cells(&prop[cell + ac], sc);
312 }
313
314 return 0;
315 }
316
317 /*******************************************************************************
318 * This function fills reg node info (base & size) with an index found by
319 * checking the reg-names node.
320 * Returns 0 on success and a negative FDT error code on failure.
321 ******************************************************************************/
fdt_get_reg_props_by_name(const void * dtb,int node,const char * name,uintptr_t * base,size_t * size)322 int fdt_get_reg_props_by_name(const void *dtb, int node, const char *name,
323 uintptr_t *base, size_t *size)
324 {
325 int index;
326
327 index = fdt_stringlist_search(dtb, node, "reg-names", name);
328 if (index < 0) {
329 return index;
330 }
331
332 return fdt_get_reg_props_by_index(dtb, node, index, base, size);
333 }
334
335 /*******************************************************************************
336 * This function gets the stdout path node.
337 * It reads the value indicated inside the device tree.
338 * Returns node offset on success and a negative FDT error code on failure.
339 ******************************************************************************/
fdt_get_stdout_node_offset(const void * dtb)340 int fdt_get_stdout_node_offset(const void *dtb)
341 {
342 int node;
343 const char *prop, *path;
344 int len;
345
346 /* The /secure-chosen node takes precedence over the standard one. */
347 node = fdt_path_offset(dtb, "/secure-chosen");
348 if (node < 0) {
349 node = fdt_path_offset(dtb, "/chosen");
350 if (node < 0) {
351 return -FDT_ERR_NOTFOUND;
352 }
353 }
354
355 prop = fdt_getprop(dtb, node, "stdout-path", NULL);
356 if (prop == NULL) {
357 return -FDT_ERR_NOTFOUND;
358 }
359
360 /* Determine the actual path length, as a colon terminates the path. */
361 path = strchr(prop, ':');
362 if (path == NULL) {
363 len = strlen(prop);
364 } else {
365 len = path - prop;
366 }
367
368 /* Aliases cannot start with a '/', so it must be the actual path. */
369 if (prop[0] == '/') {
370 return fdt_path_offset_namelen(dtb, prop, len);
371 }
372
373 /* Lookup the alias, as this contains the actual path. */
374 path = fdt_get_alias_namelen(dtb, prop, len);
375 if (path == NULL) {
376 return -FDT_ERR_NOTFOUND;
377 }
378
379 return fdt_path_offset(dtb, path);
380 }
381
382
383 /*******************************************************************************
384 * Only devices which are direct children of root node use CPU address domain.
385 * All other devices use addresses that are local to the device node and cannot
386 * directly used by CPU. Device tree provides an address translation mechanism
387 * through "ranges" property which provides mappings from local address space to
388 * parent address space. Since a device could be a child of a child node to the
389 * root node, there can be more than one level of address translation needed to
390 * map the device local address space to CPU address space.
391 * fdtw_translate_address() API performs address translation of a local address
392 * to a global address with help of various helper functions.
393 ******************************************************************************/
394
fdtw_xlat_hit(const fdt32_t * value,int child_addr_size,int parent_addr_size,int range_size,uint64_t base_address,uint64_t * translated_addr)395 static bool fdtw_xlat_hit(const fdt32_t *value, int child_addr_size,
396 int parent_addr_size, int range_size, uint64_t base_address,
397 uint64_t *translated_addr)
398 {
399 uint64_t local_address, parent_address, addr_range;
400
401 local_address = fdt_read_prop_cells(value, child_addr_size);
402 parent_address = fdt_read_prop_cells(value + child_addr_size,
403 parent_addr_size);
404 addr_range = fdt_read_prop_cells(value + child_addr_size +
405 parent_addr_size,
406 range_size);
407 VERBOSE("DT: Address %" PRIx64 " mapped to %" PRIx64 " with range %" PRIx64 "\n",
408 local_address, parent_address, addr_range);
409
410 /* Perform range check */
411 if ((base_address < local_address) ||
412 (base_address >= local_address + addr_range)) {
413 return false;
414 }
415
416 /* Found hit for the addr range that needs to be translated */
417 *translated_addr = parent_address + (base_address - local_address);
418 VERBOSE("DT: child address %" PRIx64 "mapped to %" PRIx64 " in parent bus\n",
419 local_address, parent_address);
420 return true;
421 }
422
423 #define ILLEGAL_ADDR ULL(~0)
424
fdtw_search_all_xlat_entries(const void * dtb,const struct fdt_property * ranges_prop,int local_bus,uint64_t base_address)425 static uint64_t fdtw_search_all_xlat_entries(const void *dtb,
426 const struct fdt_property *ranges_prop,
427 int local_bus, uint64_t base_address)
428 {
429 uint64_t translated_addr;
430 const fdt32_t *next_entry;
431 int parent_bus_node, nxlat_entries, length;
432 int self_addr_cells, parent_addr_cells, self_size_cells, ncells_xlat;
433
434 /*
435 * The number of cells in one translation entry in ranges is the sum of
436 * the following values:
437 * self#address-cells + parent#address-cells + self#size-cells
438 * Ex: the iofpga ranges property has one translation entry with 4 cells
439 * They represent iofpga#addr-cells + motherboard#addr-cells + iofpga#size-cells
440 * = 1 + 2 + 1
441 */
442
443 parent_bus_node = fdt_parent_offset(dtb, local_bus);
444 self_addr_cells = fdt_address_cells(dtb, local_bus);
445 self_size_cells = fdt_size_cells(dtb, local_bus);
446 parent_addr_cells = fdt_address_cells(dtb, parent_bus_node);
447
448 /* Number of cells per translation entry i.e., mapping */
449 ncells_xlat = self_addr_cells + parent_addr_cells + self_size_cells;
450
451 assert(ncells_xlat > 0);
452
453 /*
454 * Find the number of translations(mappings) specified in the current
455 * `ranges` property. Note that length represents number of bytes and
456 * is stored in big endian mode.
457 */
458 length = fdt32_to_cpu(ranges_prop->len);
459 nxlat_entries = (length/sizeof(uint32_t))/ncells_xlat;
460
461 assert(nxlat_entries > 0);
462
463 next_entry = (const fdt32_t *)ranges_prop->data;
464
465 /* Iterate over the entries in the "ranges" */
466 for (int i = 0; i < nxlat_entries; i++) {
467 if (fdtw_xlat_hit(next_entry, self_addr_cells,
468 parent_addr_cells, self_size_cells, base_address,
469 &translated_addr)){
470 return translated_addr;
471 }
472 next_entry = next_entry + ncells_xlat;
473 }
474
475 INFO("DT: No translation found for address %" PRIx64 " in node %s\n",
476 base_address, fdt_get_name(dtb, local_bus, NULL));
477 return ILLEGAL_ADDR;
478 }
479
480
481 /*******************************************************************************
482 * address mapping needs to be done recursively starting from current node to
483 * root node through all intermediate parent nodes.
484 * Sample device tree is shown here:
485
486 smb@0,0 {
487 compatible = "simple-bus";
488
489 #address-cells = <2>;
490 #size-cells = <1>;
491 ranges = <0 0 0 0x08000000 0x04000000>,
492 <1 0 0 0x14000000 0x04000000>,
493 <2 0 0 0x18000000 0x04000000>,
494 <3 0 0 0x1c000000 0x04000000>,
495 <4 0 0 0x0c000000 0x04000000>,
496 <5 0 0 0x10000000 0x04000000>;
497
498 motherboard {
499 arm,v2m-memory-map = "rs1";
500 compatible = "arm,vexpress,v2m-p1", "simple-bus";
501 #address-cells = <2>;
502 #size-cells = <1>;
503 ranges;
504
505 iofpga@3,00000000 {
506 compatible = "arm,amba-bus", "simple-bus";
507 #address-cells = <1>;
508 #size-cells = <1>;
509 ranges = <0 3 0 0x200000>;
510 v2m_serial1: uart@a0000 {
511 compatible = "arm,pl011", "arm,primecell";
512 reg = <0x0a0000 0x1000>;
513 interrupts = <0 6 4>;
514 clocks = <&v2m_clk24mhz>, <&v2m_clk24mhz>;
515 clock-names = "uartclk", "apb_pclk";
516 };
517 };
518 };
519
520 * As seen above, there are 3 levels of address translations needed. An empty
521 * `ranges` property denotes identity mapping (as seen in `motherboard` node).
522 * Each ranges property can map a set of child addresses to parent bus. Hence
523 * there can be more than 1 (translation) entry in the ranges property as seen
524 * in the `smb` node which has 6 translation entries.
525 ******************************************************************************/
526
527 /* Recursive implementation */
fdtw_translate_address(const void * dtb,int node,uint64_t base_address)528 uint64_t fdtw_translate_address(const void *dtb, int node,
529 uint64_t base_address)
530 {
531 int length, local_bus_node;
532 const char *node_name;
533 uint64_t global_address;
534
535 local_bus_node = fdt_parent_offset(dtb, node);
536 node_name = fdt_get_name(dtb, local_bus_node, NULL);
537
538 /*
539 * In the example given above, starting from the leaf node:
540 * uart@a000 represents the current node
541 * iofpga@3,00000000 represents the local bus
542 * motherboard represents the parent bus
543 */
544
545 /* Read the ranges property */
546 const struct fdt_property *property = fdt_get_property(dtb,
547 local_bus_node, "ranges", &length);
548
549 if (property == NULL) {
550 if (local_bus_node == 0) {
551 /*
552 * root node doesn't have range property as addresses
553 * are in CPU address space.
554 */
555 return base_address;
556 }
557 INFO("DT: Couldn't find ranges property in node %s\n",
558 node_name);
559 return ILLEGAL_ADDR;
560 } else if (length == 0) {
561 /* empty ranges indicates identity map to parent bus */
562 return fdtw_translate_address(dtb, local_bus_node, base_address);
563 }
564
565 VERBOSE("DT: Translation lookup in node %s at offset %d\n", node_name,
566 local_bus_node);
567 global_address = fdtw_search_all_xlat_entries(dtb, property,
568 local_bus_node, base_address);
569
570 if (global_address == ILLEGAL_ADDR) {
571 return ILLEGAL_ADDR;
572 }
573
574 /* Translate the local device address recursively */
575 return fdtw_translate_address(dtb, local_bus_node, global_address);
576 }
577
578 /*
579 * For every CPU node (`/cpus/cpu@n`) in an FDT, execute a callback passing a
580 * pointer to the FDT and the offset of the CPU node. If the return value of the
581 * callback is negative, it is treated as an error and the loop is aborted. In
582 * this situation, the value of the callback is returned from the function.
583 *
584 * Returns `0` on success, or a negative integer representing an error code.
585 */
fdtw_for_each_cpu(const void * dtb,int (* callback)(const void * dtb,int node,uintptr_t mpidr))586 int fdtw_for_each_cpu(const void *dtb,
587 int (*callback)(const void *dtb, int node, uintptr_t mpidr))
588 {
589 int ret = 0;
590 int parent, node = 0;
591
592 parent = fdt_path_offset(dtb, "/cpus");
593 if (parent < 0) {
594 return parent;
595 }
596
597 fdt_for_each_subnode(node, dtb, parent) {
598 const char *name;
599 int len;
600
601 uintptr_t mpidr = 0U;
602
603 name = fdt_get_name(dtb, node, &len);
604 if (strncmp(name, "cpu@", 4) != 0) {
605 continue;
606 }
607
608 ret = fdt_get_reg_props_by_index(dtb, node, 0, &mpidr, NULL);
609 if (ret < 0) {
610 break;
611 }
612
613 ret = callback(dtb, node, mpidr);
614 if (ret < 0) {
615 break;
616 }
617 }
618
619 return ret;
620 }
621
622 /*
623 * Find a given node in device tree. If not present, add it.
624 * Returns offset of node found/added on success, and < 0 on error.
625 */
fdtw_find_or_add_subnode(void * fdt,int parentoffset,const char * name)626 int fdtw_find_or_add_subnode(void *fdt, int parentoffset, const char *name)
627 {
628 int offset;
629
630 offset = fdt_subnode_offset(fdt, parentoffset, name);
631
632 if (offset == -FDT_ERR_NOTFOUND) {
633 offset = fdt_add_subnode(fdt, parentoffset, name);
634 }
635
636 if (offset < 0) {
637 ERROR("%s: %s: %s\n", __func__, name, fdt_strerror(offset));
638 }
639
640 return offset;
641 }
642
