1 /*
2 * drivers/firmware/qemu_fw_cfg.c
3 *
4 * Copyright 2015 Carnegie Mellon University
5 *
6 * Expose entries from QEMU's firmware configuration (fw_cfg) device in
7 * sysfs (read-only, under "/sys/firmware/qemu_fw_cfg/...").
8 *
9 * The fw_cfg device may be instantiated via either an ACPI node (on x86
10 * and select subsets of aarch64), a Device Tree node (on arm), or using
11 * a kernel module (or command line) parameter with the following syntax:
12 *
13 * [qemu_fw_cfg.]ioport=<size>@<base>[:<ctrl_off>:<data_off>[:<dma_off>]]
14 * or
15 * [qemu_fw_cfg.]mmio=<size>@<base>[:<ctrl_off>:<data_off>[:<dma_off>]]
16 *
17 * where:
18 * <size> := size of ioport or mmio range
19 * <base> := physical base address of ioport or mmio range
20 * <ctrl_off> := (optional) offset of control register
21 * <data_off> := (optional) offset of data register
22 * <dma_off> := (optional) offset of dma register
23 *
24 * e.g.:
25 * qemu_fw_cfg.ioport=12@0x510:0:1:4 (the default on x86)
26 * or
27 * qemu_fw_cfg.mmio=16@0x9020000:8:0:16 (the default on arm)
28 */
29
30 #include <linux/module.h>
31 #include <linux/mod_devicetable.h>
32 #include <linux/platform_device.h>
33 #include <linux/acpi.h>
34 #include <linux/slab.h>
35 #include <linux/io.h>
36 #include <linux/ioport.h>
37 #include <uapi/linux/qemu_fw_cfg.h>
38 #include <linux/delay.h>
39 #include <linux/crash_dump.h>
40 #include <linux/crash_core.h>
41
42 MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
43 MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
44 MODULE_LICENSE("GPL");
45
46 /* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
47 static u32 fw_cfg_rev;
48
49 /* fw_cfg device i/o register addresses */
50 static bool fw_cfg_is_mmio;
51 static phys_addr_t fw_cfg_p_base;
52 static resource_size_t fw_cfg_p_size;
53 static void __iomem *fw_cfg_dev_base;
54 static void __iomem *fw_cfg_reg_ctrl;
55 static void __iomem *fw_cfg_reg_data;
56 static void __iomem *fw_cfg_reg_dma;
57
58 /* atomic access to fw_cfg device (potentially slow i/o, so using mutex) */
59 static DEFINE_MUTEX(fw_cfg_dev_lock);
60
61 /* pick appropriate endianness for selector key */
fw_cfg_sel_endianness(u16 key)62 static void fw_cfg_sel_endianness(u16 key)
63 {
64 if (fw_cfg_is_mmio)
65 iowrite16be(key, fw_cfg_reg_ctrl);
66 else
67 iowrite16(key, fw_cfg_reg_ctrl);
68 }
69
70 #ifdef CONFIG_CRASH_CORE
fw_cfg_dma_enabled(void)71 static inline bool fw_cfg_dma_enabled(void)
72 {
73 return (fw_cfg_rev & FW_CFG_VERSION_DMA) && fw_cfg_reg_dma;
74 }
75
76 /* qemu fw_cfg device is sync today, but spec says it may become async */
fw_cfg_wait_for_control(struct fw_cfg_dma_access * d)77 static void fw_cfg_wait_for_control(struct fw_cfg_dma_access *d)
78 {
79 for (;;) {
80 u32 ctrl = be32_to_cpu(READ_ONCE(d->control));
81
82 /* do not reorder the read to d->control */
83 rmb();
84 if ((ctrl & ~FW_CFG_DMA_CTL_ERROR) == 0)
85 return;
86
87 cpu_relax();
88 }
89 }
90
fw_cfg_dma_transfer(void * address,u32 length,u32 control)91 static ssize_t fw_cfg_dma_transfer(void *address, u32 length, u32 control)
92 {
93 phys_addr_t dma;
94 struct fw_cfg_dma_access *d = NULL;
95 ssize_t ret = length;
96
97 d = kmalloc(sizeof(*d), GFP_KERNEL);
98 if (!d) {
99 ret = -ENOMEM;
100 goto end;
101 }
102
103 /* fw_cfg device does not need IOMMU protection, so use physical addresses */
104 *d = (struct fw_cfg_dma_access) {
105 .address = cpu_to_be64(address ? virt_to_phys(address) : 0),
106 .length = cpu_to_be32(length),
107 .control = cpu_to_be32(control)
108 };
109
110 dma = virt_to_phys(d);
111
112 iowrite32be((u64)dma >> 32, fw_cfg_reg_dma);
113 /* force memory to sync before notifying device via MMIO */
114 wmb();
115 iowrite32be(dma, fw_cfg_reg_dma + 4);
116
117 fw_cfg_wait_for_control(d);
118
119 if (be32_to_cpu(READ_ONCE(d->control)) & FW_CFG_DMA_CTL_ERROR) {
120 ret = -EIO;
121 }
122
123 end:
124 kfree(d);
125
126 return ret;
127 }
128 #endif
129
130 /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
fw_cfg_read_blob(u16 key,void * buf,loff_t pos,size_t count)131 static ssize_t fw_cfg_read_blob(u16 key,
132 void *buf, loff_t pos, size_t count)
133 {
134 u32 glk = -1U;
135 acpi_status status;
136
137 /* If we have ACPI, ensure mutual exclusion against any potential
138 * device access by the firmware, e.g. via AML methods:
139 */
140 status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
141 if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
142 /* Should never get here */
143 WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
144 memset(buf, 0, count);
145 return -EINVAL;
146 }
147
148 mutex_lock(&fw_cfg_dev_lock);
149 fw_cfg_sel_endianness(key);
150 while (pos-- > 0)
151 ioread8(fw_cfg_reg_data);
152 ioread8_rep(fw_cfg_reg_data, buf, count);
153 mutex_unlock(&fw_cfg_dev_lock);
154
155 acpi_release_global_lock(glk);
156 return count;
157 }
158
159 #ifdef CONFIG_CRASH_CORE
160 /* write chunk of given fw_cfg blob (caller responsible for sanity-check) */
fw_cfg_write_blob(u16 key,void * buf,loff_t pos,size_t count)161 static ssize_t fw_cfg_write_blob(u16 key,
162 void *buf, loff_t pos, size_t count)
163 {
164 u32 glk = -1U;
165 acpi_status status;
166 ssize_t ret = count;
167
168 /* If we have ACPI, ensure mutual exclusion against any potential
169 * device access by the firmware, e.g. via AML methods:
170 */
171 status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
172 if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
173 /* Should never get here */
174 WARN(1, "%s: Failed to lock ACPI!\n", __func__);
175 return -EINVAL;
176 }
177
178 mutex_lock(&fw_cfg_dev_lock);
179 if (pos == 0) {
180 ret = fw_cfg_dma_transfer(buf, count, key << 16
181 | FW_CFG_DMA_CTL_SELECT
182 | FW_CFG_DMA_CTL_WRITE);
183 } else {
184 fw_cfg_sel_endianness(key);
185 ret = fw_cfg_dma_transfer(NULL, pos, FW_CFG_DMA_CTL_SKIP);
186 if (ret < 0)
187 goto end;
188 ret = fw_cfg_dma_transfer(buf, count, FW_CFG_DMA_CTL_WRITE);
189 }
190
191 end:
192 mutex_unlock(&fw_cfg_dev_lock);
193
194 acpi_release_global_lock(glk);
195
196 return ret;
197 }
198 #endif /* CONFIG_CRASH_CORE */
199
200 /* clean up fw_cfg device i/o */
fw_cfg_io_cleanup(void)201 static void fw_cfg_io_cleanup(void)
202 {
203 if (fw_cfg_is_mmio) {
204 iounmap(fw_cfg_dev_base);
205 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
206 } else {
207 ioport_unmap(fw_cfg_dev_base);
208 release_region(fw_cfg_p_base, fw_cfg_p_size);
209 }
210 }
211
212 /* arch-specific ctrl & data register offsets are not available in ACPI, DT */
213 #if !(defined(FW_CFG_CTRL_OFF) && defined(FW_CFG_DATA_OFF))
214 # if (defined(CONFIG_ARM) || defined(CONFIG_ARM64))
215 # define FW_CFG_CTRL_OFF 0x08
216 # define FW_CFG_DATA_OFF 0x00
217 # define FW_CFG_DMA_OFF 0x10
218 # elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
219 # define FW_CFG_CTRL_OFF 0x00
220 # define FW_CFG_DATA_OFF 0x02
221 # elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */
222 # define FW_CFG_CTRL_OFF 0x00
223 # define FW_CFG_DATA_OFF 0x01
224 # define FW_CFG_DMA_OFF 0x04
225 # else
226 # error "QEMU FW_CFG not available on this architecture!"
227 # endif
228 #endif
229
230 /* initialize fw_cfg device i/o from platform data */
fw_cfg_do_platform_probe(struct platform_device * pdev)231 static int fw_cfg_do_platform_probe(struct platform_device *pdev)
232 {
233 char sig[FW_CFG_SIG_SIZE];
234 struct resource *range, *ctrl, *data, *dma;
235
236 /* acquire i/o range details */
237 fw_cfg_is_mmio = false;
238 range = platform_get_resource(pdev, IORESOURCE_IO, 0);
239 if (!range) {
240 fw_cfg_is_mmio = true;
241 range = platform_get_resource(pdev, IORESOURCE_MEM, 0);
242 if (!range)
243 return -EINVAL;
244 }
245 fw_cfg_p_base = range->start;
246 fw_cfg_p_size = resource_size(range);
247
248 if (fw_cfg_is_mmio) {
249 if (!request_mem_region(fw_cfg_p_base,
250 fw_cfg_p_size, "fw_cfg_mem"))
251 return -EBUSY;
252 fw_cfg_dev_base = ioremap(fw_cfg_p_base, fw_cfg_p_size);
253 if (!fw_cfg_dev_base) {
254 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
255 return -EFAULT;
256 }
257 } else {
258 if (!request_region(fw_cfg_p_base,
259 fw_cfg_p_size, "fw_cfg_io"))
260 return -EBUSY;
261 fw_cfg_dev_base = ioport_map(fw_cfg_p_base, fw_cfg_p_size);
262 if (!fw_cfg_dev_base) {
263 release_region(fw_cfg_p_base, fw_cfg_p_size);
264 return -EFAULT;
265 }
266 }
267
268 /* were custom register offsets provided (e.g. on the command line)? */
269 ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");
270 data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");
271 dma = platform_get_resource_byname(pdev, IORESOURCE_REG, "dma");
272 if (ctrl && data) {
273 fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;
274 fw_cfg_reg_data = fw_cfg_dev_base + data->start;
275 } else {
276 /* use architecture-specific offsets */
277 fw_cfg_reg_ctrl = fw_cfg_dev_base + FW_CFG_CTRL_OFF;
278 fw_cfg_reg_data = fw_cfg_dev_base + FW_CFG_DATA_OFF;
279 }
280
281 if (dma)
282 fw_cfg_reg_dma = fw_cfg_dev_base + dma->start;
283 #ifdef FW_CFG_DMA_OFF
284 else
285 fw_cfg_reg_dma = fw_cfg_dev_base + FW_CFG_DMA_OFF;
286 #endif
287
288 /* verify fw_cfg device signature */
289 if (fw_cfg_read_blob(FW_CFG_SIGNATURE, sig,
290 0, FW_CFG_SIG_SIZE) < 0 ||
291 memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
292 fw_cfg_io_cleanup();
293 return -ENODEV;
294 }
295
296 return 0;
297 }
298
fw_cfg_showrev(struct kobject * k,struct attribute * a,char * buf)299 static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
300 {
301 return sprintf(buf, "%u\n", fw_cfg_rev);
302 }
303
304 static const struct {
305 struct attribute attr;
306 ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);
307 } fw_cfg_rev_attr = {
308 .attr = { .name = "rev", .mode = S_IRUSR },
309 .show = fw_cfg_showrev,
310 };
311
312 /* fw_cfg_sysfs_entry type */
313 struct fw_cfg_sysfs_entry {
314 struct kobject kobj;
315 u32 size;
316 u16 select;
317 char name[FW_CFG_MAX_FILE_PATH];
318 struct list_head list;
319 };
320
321 #ifdef CONFIG_CRASH_CORE
fw_cfg_write_vmcoreinfo(const struct fw_cfg_file * f)322 static ssize_t fw_cfg_write_vmcoreinfo(const struct fw_cfg_file *f)
323 {
324 static struct fw_cfg_vmcoreinfo *data;
325 ssize_t ret;
326
327 data = kmalloc(sizeof(struct fw_cfg_vmcoreinfo), GFP_KERNEL);
328 if (!data)
329 return -ENOMEM;
330
331 *data = (struct fw_cfg_vmcoreinfo) {
332 .guest_format = cpu_to_le16(FW_CFG_VMCOREINFO_FORMAT_ELF),
333 .size = cpu_to_le32(VMCOREINFO_NOTE_SIZE),
334 .paddr = cpu_to_le64(paddr_vmcoreinfo_note())
335 };
336 /* spare ourself reading host format support for now since we
337 * don't know what else to format - host may ignore ours
338 */
339 ret = fw_cfg_write_blob(be16_to_cpu(f->select), data,
340 0, sizeof(struct fw_cfg_vmcoreinfo));
341
342 kfree(data);
343 return ret;
344 }
345 #endif /* CONFIG_CRASH_CORE */
346
347 /* get fw_cfg_sysfs_entry from kobject member */
to_entry(struct kobject * kobj)348 static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
349 {
350 return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);
351 }
352
353 /* fw_cfg_sysfs_attribute type */
354 struct fw_cfg_sysfs_attribute {
355 struct attribute attr;
356 ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);
357 };
358
359 /* get fw_cfg_sysfs_attribute from attribute member */
to_attr(struct attribute * attr)360 static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)
361 {
362 return container_of(attr, struct fw_cfg_sysfs_attribute, attr);
363 }
364
365 /* global cache of fw_cfg_sysfs_entry objects */
366 static LIST_HEAD(fw_cfg_entry_cache);
367
368 /* kobjects removed lazily by kernel, mutual exclusion needed */
369 static DEFINE_SPINLOCK(fw_cfg_cache_lock);
370
fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry * entry)371 static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)
372 {
373 spin_lock(&fw_cfg_cache_lock);
374 list_add_tail(&entry->list, &fw_cfg_entry_cache);
375 spin_unlock(&fw_cfg_cache_lock);
376 }
377
fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry * entry)378 static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)
379 {
380 spin_lock(&fw_cfg_cache_lock);
381 list_del(&entry->list);
382 spin_unlock(&fw_cfg_cache_lock);
383 }
384
fw_cfg_sysfs_cache_cleanup(void)385 static void fw_cfg_sysfs_cache_cleanup(void)
386 {
387 struct fw_cfg_sysfs_entry *entry, *next;
388
389 list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {
390 /* will end up invoking fw_cfg_sysfs_cache_delist()
391 * via each object's release() method (i.e. destructor)
392 */
393 kobject_put(&entry->kobj);
394 }
395 }
396
397 /* default_attrs: per-entry attributes and show methods */
398
399 #define FW_CFG_SYSFS_ATTR(_attr) \
400 struct fw_cfg_sysfs_attribute fw_cfg_sysfs_attr_##_attr = { \
401 .attr = { .name = __stringify(_attr), .mode = S_IRUSR }, \
402 .show = fw_cfg_sysfs_show_##_attr, \
403 }
404
fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry * e,char * buf)405 static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)
406 {
407 return sprintf(buf, "%u\n", e->size);
408 }
409
fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry * e,char * buf)410 static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)
411 {
412 return sprintf(buf, "%u\n", e->select);
413 }
414
fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry * e,char * buf)415 static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)
416 {
417 return sprintf(buf, "%s\n", e->name);
418 }
419
420 static FW_CFG_SYSFS_ATTR(size);
421 static FW_CFG_SYSFS_ATTR(key);
422 static FW_CFG_SYSFS_ATTR(name);
423
424 static struct attribute *fw_cfg_sysfs_entry_attrs[] = {
425 &fw_cfg_sysfs_attr_size.attr,
426 &fw_cfg_sysfs_attr_key.attr,
427 &fw_cfg_sysfs_attr_name.attr,
428 NULL,
429 };
430
431 /* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */
fw_cfg_sysfs_attr_show(struct kobject * kobj,struct attribute * a,char * buf)432 static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,
433 char *buf)
434 {
435 struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
436 struct fw_cfg_sysfs_attribute *attr = to_attr(a);
437
438 return attr->show(entry, buf);
439 }
440
441 static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {
442 .show = fw_cfg_sysfs_attr_show,
443 };
444
445 /* release: destructor, to be called via kobject_put() */
fw_cfg_sysfs_release_entry(struct kobject * kobj)446 static void fw_cfg_sysfs_release_entry(struct kobject *kobj)
447 {
448 struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
449
450 fw_cfg_sysfs_cache_delist(entry);
451 kfree(entry);
452 }
453
454 /* kobj_type: ties together all properties required to register an entry */
455 static struct kobj_type fw_cfg_sysfs_entry_ktype = {
456 .default_attrs = fw_cfg_sysfs_entry_attrs,
457 .sysfs_ops = &fw_cfg_sysfs_attr_ops,
458 .release = fw_cfg_sysfs_release_entry,
459 };
460
461 /* raw-read method and attribute */
fw_cfg_sysfs_read_raw(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t pos,size_t count)462 static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
463 struct bin_attribute *bin_attr,
464 char *buf, loff_t pos, size_t count)
465 {
466 struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
467
468 if (pos > entry->size)
469 return -EINVAL;
470
471 if (count > entry->size - pos)
472 count = entry->size - pos;
473
474 return fw_cfg_read_blob(entry->select, buf, pos, count);
475 }
476
477 static struct bin_attribute fw_cfg_sysfs_attr_raw = {
478 .attr = { .name = "raw", .mode = S_IRUSR },
479 .read = fw_cfg_sysfs_read_raw,
480 };
481
482 /*
483 * Create a kset subdirectory matching each '/' delimited dirname token
484 * in 'name', starting with sysfs kset/folder 'dir'; At the end, create
485 * a symlink directed at the given 'target'.
486 * NOTE: We do this on a best-effort basis, since 'name' is not guaranteed
487 * to be a well-behaved path name. Whenever a symlink vs. kset directory
488 * name collision occurs, the kernel will issue big scary warnings while
489 * refusing to add the offending link or directory. We follow up with our
490 * own, slightly less scary error messages explaining the situation :)
491 */
fw_cfg_build_symlink(struct kset * dir,struct kobject * target,const char * name)492 static int fw_cfg_build_symlink(struct kset *dir,
493 struct kobject *target, const char *name)
494 {
495 int ret;
496 struct kset *subdir;
497 struct kobject *ko;
498 char *name_copy, *p, *tok;
499
500 if (!dir || !target || !name || !*name)
501 return -EINVAL;
502
503 /* clone a copy of name for parsing */
504 name_copy = p = kstrdup(name, GFP_KERNEL);
505 if (!name_copy)
506 return -ENOMEM;
507
508 /* create folders for each dirname token, then symlink for basename */
509 while ((tok = strsep(&p, "/")) && *tok) {
510
511 /* last (basename) token? If so, add symlink here */
512 if (!p || !*p) {
513 ret = sysfs_create_link(&dir->kobj, target, tok);
514 break;
515 }
516
517 /* does the current dir contain an item named after tok ? */
518 ko = kset_find_obj(dir, tok);
519 if (ko) {
520 /* drop reference added by kset_find_obj */
521 kobject_put(ko);
522
523 /* ko MUST be a kset - we're about to use it as one ! */
524 if (ko->ktype != dir->kobj.ktype) {
525 ret = -EINVAL;
526 break;
527 }
528
529 /* descend into already existing subdirectory */
530 dir = to_kset(ko);
531 } else {
532 /* create new subdirectory kset */
533 subdir = kzalloc(sizeof(struct kset), GFP_KERNEL);
534 if (!subdir) {
535 ret = -ENOMEM;
536 break;
537 }
538 subdir->kobj.kset = dir;
539 subdir->kobj.ktype = dir->kobj.ktype;
540 ret = kobject_set_name(&subdir->kobj, "%s", tok);
541 if (ret) {
542 kfree(subdir);
543 break;
544 }
545 ret = kset_register(subdir);
546 if (ret) {
547 kfree(subdir);
548 break;
549 }
550
551 /* descend into newly created subdirectory */
552 dir = subdir;
553 }
554 }
555
556 /* we're done with cloned copy of name */
557 kfree(name_copy);
558 return ret;
559 }
560
561 /* recursively unregister fw_cfg/by_name/ kset directory tree */
fw_cfg_kset_unregister_recursive(struct kset * kset)562 static void fw_cfg_kset_unregister_recursive(struct kset *kset)
563 {
564 struct kobject *k, *next;
565
566 list_for_each_entry_safe(k, next, &kset->list, entry)
567 /* all set members are ksets too, but check just in case... */
568 if (k->ktype == kset->kobj.ktype)
569 fw_cfg_kset_unregister_recursive(to_kset(k));
570
571 /* symlinks are cleanly and automatically removed with the directory */
572 kset_unregister(kset);
573 }
574
575 /* kobjects & kset representing top-level, by_key, and by_name folders */
576 static struct kobject *fw_cfg_top_ko;
577 static struct kobject *fw_cfg_sel_ko;
578 static struct kset *fw_cfg_fname_kset;
579
580 /* register an individual fw_cfg file */
fw_cfg_register_file(const struct fw_cfg_file * f)581 static int fw_cfg_register_file(const struct fw_cfg_file *f)
582 {
583 int err;
584 struct fw_cfg_sysfs_entry *entry;
585
586 #ifdef CONFIG_CRASH_CORE
587 if (fw_cfg_dma_enabled() &&
588 strcmp(f->name, FW_CFG_VMCOREINFO_FILENAME) == 0 &&
589 !is_kdump_kernel()) {
590 if (fw_cfg_write_vmcoreinfo(f) < 0)
591 pr_warn("fw_cfg: failed to write vmcoreinfo");
592 }
593 #endif
594
595 /* allocate new entry */
596 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
597 if (!entry)
598 return -ENOMEM;
599
600 /* set file entry information */
601 entry->size = be32_to_cpu(f->size);
602 entry->select = be16_to_cpu(f->select);
603 memcpy(entry->name, f->name, FW_CFG_MAX_FILE_PATH);
604
605 /* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
606 err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,
607 fw_cfg_sel_ko, "%d", entry->select);
608 if (err)
609 goto err_register;
610
611 /* add raw binary content access */
612 err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);
613 if (err)
614 goto err_add_raw;
615
616 /* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
617 fw_cfg_build_symlink(fw_cfg_fname_kset, &entry->kobj, entry->name);
618
619 /* success, add entry to global cache */
620 fw_cfg_sysfs_cache_enlist(entry);
621 return 0;
622
623 err_add_raw:
624 kobject_del(&entry->kobj);
625 err_register:
626 kfree(entry);
627 return err;
628 }
629
630 /* iterate over all fw_cfg directory entries, registering each one */
fw_cfg_register_dir_entries(void)631 static int fw_cfg_register_dir_entries(void)
632 {
633 int ret = 0;
634 __be32 files_count;
635 u32 count, i;
636 struct fw_cfg_file *dir;
637 size_t dir_size;
638
639 ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, &files_count,
640 0, sizeof(files_count));
641 if (ret < 0)
642 return ret;
643
644 count = be32_to_cpu(files_count);
645 dir_size = count * sizeof(struct fw_cfg_file);
646
647 dir = kmalloc(dir_size, GFP_KERNEL);
648 if (!dir)
649 return -ENOMEM;
650
651 ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, dir,
652 sizeof(files_count), dir_size);
653 if (ret < 0)
654 goto end;
655
656 for (i = 0; i < count; i++) {
657 ret = fw_cfg_register_file(&dir[i]);
658 if (ret)
659 break;
660 }
661
662 end:
663 kfree(dir);
664 return ret;
665 }
666
667 /* unregister top-level or by_key folder */
fw_cfg_kobj_cleanup(struct kobject * kobj)668 static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)
669 {
670 kobject_del(kobj);
671 kobject_put(kobj);
672 }
673
fw_cfg_sysfs_probe(struct platform_device * pdev)674 static int fw_cfg_sysfs_probe(struct platform_device *pdev)
675 {
676 int err;
677 __le32 rev;
678
679 /* NOTE: If we supported multiple fw_cfg devices, we'd first create
680 * a subdirectory named after e.g. pdev->id, then hang per-device
681 * by_key (and by_name) subdirectories underneath it. However, only
682 * one fw_cfg device exist system-wide, so if one was already found
683 * earlier, we might as well stop here.
684 */
685 if (fw_cfg_sel_ko)
686 return -EBUSY;
687
688 /* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
689 err = -ENOMEM;
690 fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
691 if (!fw_cfg_sel_ko)
692 goto err_sel;
693 fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
694 if (!fw_cfg_fname_kset)
695 goto err_name;
696
697 /* initialize fw_cfg device i/o from platform data */
698 err = fw_cfg_do_platform_probe(pdev);
699 if (err)
700 goto err_probe;
701
702 /* get revision number, add matching top-level attribute */
703 err = fw_cfg_read_blob(FW_CFG_ID, &rev, 0, sizeof(rev));
704 if (err < 0)
705 goto err_probe;
706
707 fw_cfg_rev = le32_to_cpu(rev);
708 err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
709 if (err)
710 goto err_rev;
711
712 /* process fw_cfg file directory entry, registering each file */
713 err = fw_cfg_register_dir_entries();
714 if (err)
715 goto err_dir;
716
717 /* success */
718 pr_debug("fw_cfg: loaded.\n");
719 return 0;
720
721 err_dir:
722 fw_cfg_sysfs_cache_cleanup();
723 sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
724 err_rev:
725 fw_cfg_io_cleanup();
726 err_probe:
727 fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
728 err_name:
729 fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
730 err_sel:
731 return err;
732 }
733
fw_cfg_sysfs_remove(struct platform_device * pdev)734 static int fw_cfg_sysfs_remove(struct platform_device *pdev)
735 {
736 pr_debug("fw_cfg: unloading.\n");
737 fw_cfg_sysfs_cache_cleanup();
738 sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
739 fw_cfg_io_cleanup();
740 fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
741 fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
742 return 0;
743 }
744
745 static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
746 { .compatible = "qemu,fw-cfg-mmio", },
747 {},
748 };
749 MODULE_DEVICE_TABLE(of, fw_cfg_sysfs_mmio_match);
750
751 #ifdef CONFIG_ACPI
752 static const struct acpi_device_id fw_cfg_sysfs_acpi_match[] = {
753 { FW_CFG_ACPI_DEVICE_ID, },
754 {},
755 };
756 MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
757 #endif
758
759 static struct platform_driver fw_cfg_sysfs_driver = {
760 .probe = fw_cfg_sysfs_probe,
761 .remove = fw_cfg_sysfs_remove,
762 .driver = {
763 .name = "fw_cfg",
764 .of_match_table = fw_cfg_sysfs_mmio_match,
765 .acpi_match_table = ACPI_PTR(fw_cfg_sysfs_acpi_match),
766 },
767 };
768
769 #ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
770
771 static struct platform_device *fw_cfg_cmdline_dev;
772
773 /* this probably belongs in e.g. include/linux/types.h,
774 * but right now we are the only ones doing it...
775 */
776 #ifdef CONFIG_PHYS_ADDR_T_64BIT
777 #define __PHYS_ADDR_PREFIX "ll"
778 #else
779 #define __PHYS_ADDR_PREFIX ""
780 #endif
781
782 /* use special scanf/printf modifier for phys_addr_t, resource_size_t */
783 #define PH_ADDR_SCAN_FMT "@%" __PHYS_ADDR_PREFIX "i%n" \
784 ":%" __PHYS_ADDR_PREFIX "i" \
785 ":%" __PHYS_ADDR_PREFIX "i%n" \
786 ":%" __PHYS_ADDR_PREFIX "i%n"
787
788 #define PH_ADDR_PR_1_FMT "0x%" __PHYS_ADDR_PREFIX "x@" \
789 "0x%" __PHYS_ADDR_PREFIX "x"
790
791 #define PH_ADDR_PR_3_FMT PH_ADDR_PR_1_FMT \
792 ":%" __PHYS_ADDR_PREFIX "u" \
793 ":%" __PHYS_ADDR_PREFIX "u"
794
795 #define PH_ADDR_PR_4_FMT PH_ADDR_PR_3_FMT \
796 ":%" __PHYS_ADDR_PREFIX "u"
797
fw_cfg_cmdline_set(const char * arg,const struct kernel_param * kp)798 static int fw_cfg_cmdline_set(const char *arg, const struct kernel_param *kp)
799 {
800 struct resource res[4] = {};
801 char *str;
802 phys_addr_t base;
803 resource_size_t size, ctrl_off, data_off, dma_off;
804 int processed, consumed = 0;
805
806 /* only one fw_cfg device can exist system-wide, so if one
807 * was processed on the command line already, we might as
808 * well stop here.
809 */
810 if (fw_cfg_cmdline_dev) {
811 /* avoid leaking previously registered device */
812 platform_device_unregister(fw_cfg_cmdline_dev);
813 return -EINVAL;
814 }
815
816 /* consume "<size>" portion of command line argument */
817 size = memparse(arg, &str);
818
819 /* get "@<base>[:<ctrl_off>:<data_off>[:<dma_off>]]" chunks */
820 processed = sscanf(str, PH_ADDR_SCAN_FMT,
821 &base, &consumed,
822 &ctrl_off, &data_off, &consumed,
823 &dma_off, &consumed);
824
825 /* sscanf() must process precisely 1, 3 or 4 chunks:
826 * <base> is mandatory, optionally followed by <ctrl_off>
827 * and <data_off>, and <dma_off>;
828 * there must be no extra characters after the last chunk,
829 * so str[consumed] must be '\0'.
830 */
831 if (str[consumed] ||
832 (processed != 1 && processed != 3 && processed != 4))
833 return -EINVAL;
834
835 res[0].start = base;
836 res[0].end = base + size - 1;
837 res[0].flags = !strcmp(kp->name, "mmio") ? IORESOURCE_MEM :
838 IORESOURCE_IO;
839
840 /* insert register offsets, if provided */
841 if (processed > 1) {
842 res[1].name = "ctrl";
843 res[1].start = ctrl_off;
844 res[1].flags = IORESOURCE_REG;
845 res[2].name = "data";
846 res[2].start = data_off;
847 res[2].flags = IORESOURCE_REG;
848 }
849 if (processed > 3) {
850 res[3].name = "dma";
851 res[3].start = dma_off;
852 res[3].flags = IORESOURCE_REG;
853 }
854
855 /* "processed" happens to nicely match the number of resources
856 * we need to pass in to this platform device.
857 */
858 fw_cfg_cmdline_dev = platform_device_register_simple("fw_cfg",
859 PLATFORM_DEVID_NONE, res, processed);
860
861 return PTR_ERR_OR_ZERO(fw_cfg_cmdline_dev);
862 }
863
fw_cfg_cmdline_get(char * buf,const struct kernel_param * kp)864 static int fw_cfg_cmdline_get(char *buf, const struct kernel_param *kp)
865 {
866 /* stay silent if device was not configured via the command
867 * line, or if the parameter name (ioport/mmio) doesn't match
868 * the device setting
869 */
870 if (!fw_cfg_cmdline_dev ||
871 (!strcmp(kp->name, "mmio") ^
872 (fw_cfg_cmdline_dev->resource[0].flags == IORESOURCE_MEM)))
873 return 0;
874
875 switch (fw_cfg_cmdline_dev->num_resources) {
876 case 1:
877 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_1_FMT,
878 resource_size(&fw_cfg_cmdline_dev->resource[0]),
879 fw_cfg_cmdline_dev->resource[0].start);
880 case 3:
881 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_3_FMT,
882 resource_size(&fw_cfg_cmdline_dev->resource[0]),
883 fw_cfg_cmdline_dev->resource[0].start,
884 fw_cfg_cmdline_dev->resource[1].start,
885 fw_cfg_cmdline_dev->resource[2].start);
886 case 4:
887 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_4_FMT,
888 resource_size(&fw_cfg_cmdline_dev->resource[0]),
889 fw_cfg_cmdline_dev->resource[0].start,
890 fw_cfg_cmdline_dev->resource[1].start,
891 fw_cfg_cmdline_dev->resource[2].start,
892 fw_cfg_cmdline_dev->resource[3].start);
893 }
894
895 /* Should never get here */
896 WARN(1, "Unexpected number of resources: %d\n",
897 fw_cfg_cmdline_dev->num_resources);
898 return 0;
899 }
900
901 static const struct kernel_param_ops fw_cfg_cmdline_param_ops = {
902 .set = fw_cfg_cmdline_set,
903 .get = fw_cfg_cmdline_get,
904 };
905
906 device_param_cb(ioport, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
907 device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
908
909 #endif /* CONFIG_FW_CFG_SYSFS_CMDLINE */
910
fw_cfg_sysfs_init(void)911 static int __init fw_cfg_sysfs_init(void)
912 {
913 int ret;
914
915 /* create /sys/firmware/qemu_fw_cfg/ top level directory */
916 fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);
917 if (!fw_cfg_top_ko)
918 return -ENOMEM;
919
920 ret = platform_driver_register(&fw_cfg_sysfs_driver);
921 if (ret)
922 fw_cfg_kobj_cleanup(fw_cfg_top_ko);
923
924 return ret;
925 }
926
fw_cfg_sysfs_exit(void)927 static void __exit fw_cfg_sysfs_exit(void)
928 {
929 platform_driver_unregister(&fw_cfg_sysfs_driver);
930
931 #ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
932 platform_device_unregister(fw_cfg_cmdline_dev);
933 #endif
934
935 /* clean up /sys/firmware/qemu_fw_cfg/ */
936 fw_cfg_kobj_cleanup(fw_cfg_top_ko);
937 }
938
939 module_init(fw_cfg_sysfs_init);
940 module_exit(fw_cfg_sysfs_exit);
941