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/vmcore_info.h>
41
42MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
43MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
44MODULE_LICENSE("GPL");
45
46/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
47static u32 fw_cfg_rev;
48
49/* fw_cfg device i/o register addresses */
50static bool fw_cfg_is_mmio;
51static phys_addr_t fw_cfg_p_base;
52static resource_size_t fw_cfg_p_size;
53static void __iomem *fw_cfg_dev_base;
54static void __iomem *fw_cfg_reg_ctrl;
55static void __iomem *fw_cfg_reg_data;
56static void __iomem *fw_cfg_reg_dma;
57
58/* atomic access to fw_cfg device (potentially slow i/o, so using mutex) */
59static DEFINE_MUTEX(fw_cfg_dev_lock);
60
61/* pick appropriate endianness for selector key */
62static 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_VMCORE_INFO
71static 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 */
77static 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
91static 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(size: 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(address: 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
123end:
124 kfree(objp: d);
125
126 return ret;
127}
128#endif
129
130/* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
131static 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, handle: &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(port: fw_cfg_reg_data, buf, count);
153 mutex_unlock(lock: &fw_cfg_dev_lock);
154
155 acpi_release_global_lock(handle: glk);
156 return count;
157}
158
159#ifdef CONFIG_VMCORE_INFO
160/* write chunk of given fw_cfg blob (caller responsible for sanity-check) */
161static 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, handle: &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(address: buf, length: count, control: 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, length: pos, FW_CFG_DMA_CTL_SKIP);
186 if (ret < 0)
187 goto end;
188 ret = fw_cfg_dma_transfer(address: buf, length: count, FW_CFG_DMA_CTL_WRITE);
189 }
190
191end:
192 mutex_unlock(lock: &fw_cfg_dev_lock);
193
194 acpi_release_global_lock(handle: glk);
195
196 return ret;
197}
198#endif /* CONFIG_VMCORE_INFO */
199
200/* clean up fw_cfg device i/o */
201static void fw_cfg_io_cleanup(void)
202{
203 if (fw_cfg_is_mmio) {
204 iounmap(addr: fw_cfg_dev_base);
205 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
206 } else {
207 ioport_unmap(p: 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) || defined(CONFIG_RISCV))
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_PARISC) /* parisc */
219# define FW_CFG_CTRL_OFF 0x00
220# define FW_CFG_DATA_OFF 0x04
221# elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
222# define FW_CFG_CTRL_OFF 0x00
223# define FW_CFG_DATA_OFF 0x02
224# elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */
225# define FW_CFG_CTRL_OFF 0x00
226# define FW_CFG_DATA_OFF 0x01
227# define FW_CFG_DMA_OFF 0x04
228# else
229# error "QEMU FW_CFG not available on this architecture!"
230# endif
231#endif
232
233/* initialize fw_cfg device i/o from platform data */
234static int fw_cfg_do_platform_probe(struct platform_device *pdev)
235{
236 char sig[FW_CFG_SIG_SIZE];
237 struct resource *range, *ctrl, *data, *dma;
238
239 /* acquire i/o range details */
240 fw_cfg_is_mmio = false;
241 range = platform_get_resource(pdev, IORESOURCE_IO, 0);
242 if (!range) {
243 fw_cfg_is_mmio = true;
244 range = platform_get_resource(pdev, IORESOURCE_MEM, 0);
245 if (!range)
246 return -EINVAL;
247 }
248 fw_cfg_p_base = range->start;
249 fw_cfg_p_size = resource_size(res: range);
250
251 if (fw_cfg_is_mmio) {
252 if (!request_mem_region(fw_cfg_p_base,
253 fw_cfg_p_size, "fw_cfg_mem"))
254 return -EBUSY;
255 fw_cfg_dev_base = ioremap(offset: fw_cfg_p_base, size: fw_cfg_p_size);
256 if (!fw_cfg_dev_base) {
257 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
258 return -EFAULT;
259 }
260 } else {
261 if (!request_region(fw_cfg_p_base,
262 fw_cfg_p_size, "fw_cfg_io"))
263 return -EBUSY;
264 fw_cfg_dev_base = ioport_map(port: fw_cfg_p_base, nr: fw_cfg_p_size);
265 if (!fw_cfg_dev_base) {
266 release_region(fw_cfg_p_base, fw_cfg_p_size);
267 return -EFAULT;
268 }
269 }
270
271 /* were custom register offsets provided (e.g. on the command line)? */
272 ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");
273 data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");
274 dma = platform_get_resource_byname(pdev, IORESOURCE_REG, "dma");
275 if (ctrl && data) {
276 fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;
277 fw_cfg_reg_data = fw_cfg_dev_base + data->start;
278 } else {
279 /* use architecture-specific offsets */
280 fw_cfg_reg_ctrl = fw_cfg_dev_base + FW_CFG_CTRL_OFF;
281 fw_cfg_reg_data = fw_cfg_dev_base + FW_CFG_DATA_OFF;
282 }
283
284 if (dma)
285 fw_cfg_reg_dma = fw_cfg_dev_base + dma->start;
286#ifdef FW_CFG_DMA_OFF
287 else
288 fw_cfg_reg_dma = fw_cfg_dev_base + FW_CFG_DMA_OFF;
289#endif
290
291 /* verify fw_cfg device signature */
292 if (fw_cfg_read_blob(FW_CFG_SIGNATURE, buf: sig,
293 pos: 0, FW_CFG_SIG_SIZE) < 0 ||
294 memcmp(p: sig, q: "QEMU", FW_CFG_SIG_SIZE) != 0) {
295 fw_cfg_io_cleanup();
296 return -ENODEV;
297 }
298
299 return 0;
300}
301
302static ssize_t fw_cfg_showrev(struct kobject *k, struct kobj_attribute *a,
303 char *buf)
304{
305 return sprintf(buf, fmt: "%u\n", fw_cfg_rev);
306}
307
308static const struct kobj_attribute fw_cfg_rev_attr = {
309 .attr = { .name = "rev", .mode = S_IRUSR },
310 .show = fw_cfg_showrev,
311};
312
313/* fw_cfg_sysfs_entry type */
314struct fw_cfg_sysfs_entry {
315 struct kobject kobj;
316 u32 size;
317 u16 select;
318 char name[FW_CFG_MAX_FILE_PATH];
319 struct list_head list;
320};
321
322#ifdef CONFIG_VMCORE_INFO
323static ssize_t fw_cfg_write_vmcoreinfo(const struct fw_cfg_file *f)
324{
325 static struct fw_cfg_vmcoreinfo *data;
326 ssize_t ret;
327
328 data = kmalloc(size: sizeof(struct fw_cfg_vmcoreinfo), GFP_KERNEL);
329 if (!data)
330 return -ENOMEM;
331
332 *data = (struct fw_cfg_vmcoreinfo) {
333 .guest_format = cpu_to_le16(FW_CFG_VMCOREINFO_FORMAT_ELF),
334 .size = cpu_to_le32(VMCOREINFO_NOTE_SIZE),
335 .paddr = cpu_to_le64(paddr_vmcoreinfo_note())
336 };
337 /* spare ourself reading host format support for now since we
338 * don't know what else to format - host may ignore ours
339 */
340 ret = fw_cfg_write_blob(be16_to_cpu(f->select), buf: data,
341 pos: 0, count: sizeof(struct fw_cfg_vmcoreinfo));
342
343 kfree(objp: data);
344 return ret;
345}
346#endif /* CONFIG_VMCORE_INFO */
347
348/* get fw_cfg_sysfs_entry from kobject member */
349static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
350{
351 return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);
352}
353
354/* fw_cfg_sysfs_attribute type */
355struct fw_cfg_sysfs_attribute {
356 struct attribute attr;
357 ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);
358};
359
360/* get fw_cfg_sysfs_attribute from attribute member */
361static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)
362{
363 return container_of(attr, struct fw_cfg_sysfs_attribute, attr);
364}
365
366/* global cache of fw_cfg_sysfs_entry objects */
367static LIST_HEAD(fw_cfg_entry_cache);
368
369/* kobjects removed lazily by kernel, mutual exclusion needed */
370static DEFINE_SPINLOCK(fw_cfg_cache_lock);
371
372static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)
373{
374 spin_lock(lock: &fw_cfg_cache_lock);
375 list_add_tail(new: &entry->list, head: &fw_cfg_entry_cache);
376 spin_unlock(lock: &fw_cfg_cache_lock);
377}
378
379static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)
380{
381 spin_lock(lock: &fw_cfg_cache_lock);
382 list_del(entry: &entry->list);
383 spin_unlock(lock: &fw_cfg_cache_lock);
384}
385
386static void fw_cfg_sysfs_cache_cleanup(void)
387{
388 struct fw_cfg_sysfs_entry *entry, *next;
389
390 list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {
391 fw_cfg_sysfs_cache_delist(entry);
392 kobject_del(kobj: &entry->kobj);
393 kobject_put(kobj: &entry->kobj);
394 }
395}
396
397/* per-entry attributes and show methods */
398
399#define FW_CFG_SYSFS_ATTR(_attr) \
400struct 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
405static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)
406{
407 return sprintf(buf, fmt: "%u\n", e->size);
408}
409
410static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)
411{
412 return sprintf(buf, fmt: "%u\n", e->select);
413}
414
415static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)
416{
417 return sprintf(buf, fmt: "%s\n", e->name);
418}
419
420static FW_CFG_SYSFS_ATTR(size);
421static FW_CFG_SYSFS_ATTR(key);
422static FW_CFG_SYSFS_ATTR(name);
423
424static 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};
430ATTRIBUTE_GROUPS(fw_cfg_sysfs_entry);
431
432/* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */
433static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,
434 char *buf)
435{
436 struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
437 struct fw_cfg_sysfs_attribute *attr = to_attr(attr: a);
438
439 return attr->show(entry, buf);
440}
441
442static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {
443 .show = fw_cfg_sysfs_attr_show,
444};
445
446/* release: destructor, to be called via kobject_put() */
447static void fw_cfg_sysfs_release_entry(struct kobject *kobj)
448{
449 struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
450
451 kfree(objp: entry);
452}
453
454/* kobj_type: ties together all properties required to register an entry */
455static struct kobj_type fw_cfg_sysfs_entry_ktype = {
456 .default_groups = fw_cfg_sysfs_entry_groups,
457 .sysfs_ops = &fw_cfg_sysfs_attr_ops,
458 .release = fw_cfg_sysfs_release_entry,
459};
460
461/* raw-read method and attribute */
462static 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(key: entry->select, buf, pos, count);
475}
476
477static 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 */
492static 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(s: 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(kobj: &dir->kobj, target, name: 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(kobj: 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(kobj: ko);
531 } else {
532 /* create new subdirectory kset */
533 subdir = kzalloc(size: 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(kobj: &subdir->kobj, name: "%s", tok);
541 if (ret) {
542 kfree(objp: subdir);
543 break;
544 }
545 ret = kset_register(kset: subdir);
546 if (ret) {
547 kfree(objp: 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(objp: name_copy);
558 return ret;
559}
560
561/* recursively unregister fw_cfg/by_name/ kset directory tree */
562static 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(kset: to_kset(kobj: 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 */
576static struct kobject *fw_cfg_top_ko;
577static struct kobject *fw_cfg_sel_ko;
578static struct kset *fw_cfg_fname_kset;
579
580/* register an individual fw_cfg file */
581static 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_VMCORE_INFO
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(size: 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 strscpy(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(kobj: &entry->kobj, ktype: &fw_cfg_sysfs_entry_ktype,
607 parent: fw_cfg_sel_ko, fmt: "%d", entry->select);
608 if (err)
609 goto err_put_entry;
610
611 /* add raw binary content access */
612 err = sysfs_create_bin_file(kobj: &entry->kobj, attr: &fw_cfg_sysfs_attr_raw);
613 if (err)
614 goto err_del_entry;
615
616 /* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
617 fw_cfg_build_symlink(dir: fw_cfg_fname_kset, target: &entry->kobj, name: entry->name);
618
619 /* success, add entry to global cache */
620 fw_cfg_sysfs_cache_enlist(entry);
621 return 0;
622
623err_del_entry:
624 kobject_del(kobj: &entry->kobj);
625err_put_entry:
626 kobject_put(kobj: &entry->kobj);
627 return err;
628}
629
630/* iterate over all fw_cfg directory entries, registering each one */
631static 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, buf: &files_count,
640 pos: 0, count: 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(size: dir_size, GFP_KERNEL);
648 if (!dir)
649 return -ENOMEM;
650
651 ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, buf: dir,
652 pos: sizeof(files_count), count: dir_size);
653 if (ret < 0)
654 goto end;
655
656 for (i = 0; i < count; i++) {
657 ret = fw_cfg_register_file(f: &dir[i]);
658 if (ret)
659 break;
660 }
661
662end:
663 kfree(objp: dir);
664 return ret;
665}
666
667/* unregister top-level or by_key folder */
668static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)
669{
670 kobject_del(kobj);
671 kobject_put(kobj);
672}
673
674static 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(name: "by_key", parent: fw_cfg_top_ko);
691 if (!fw_cfg_sel_ko)
692 goto err_sel;
693 fw_cfg_fname_kset = kset_create_and_add(name: "by_name", NULL, parent_kobj: 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, buf: &rev, pos: 0, count: sizeof(rev));
704 if (err < 0)
705 goto err_probe;
706
707 fw_cfg_rev = le32_to_cpu(rev);
708 err = sysfs_create_file(kobj: fw_cfg_top_ko, attr: &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
721err_dir:
722 fw_cfg_sysfs_cache_cleanup();
723 sysfs_remove_file(kobj: fw_cfg_top_ko, attr: &fw_cfg_rev_attr.attr);
724err_rev:
725 fw_cfg_io_cleanup();
726err_probe:
727 fw_cfg_kset_unregister_recursive(kset: fw_cfg_fname_kset);
728err_name:
729 fw_cfg_kobj_cleanup(kobj: fw_cfg_sel_ko);
730err_sel:
731 return err;
732}
733
734static void 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(kobj: fw_cfg_top_ko, attr: &fw_cfg_rev_attr.attr);
739 fw_cfg_io_cleanup();
740 fw_cfg_kset_unregister_recursive(kset: fw_cfg_fname_kset);
741 fw_cfg_kobj_cleanup(kobj: fw_cfg_sel_ko);
742}
743
744static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
745 { .compatible = "qemu,fw-cfg-mmio", },
746 {},
747};
748MODULE_DEVICE_TABLE(of, fw_cfg_sysfs_mmio_match);
749
750#ifdef CONFIG_ACPI
751static const struct acpi_device_id fw_cfg_sysfs_acpi_match[] = {
752 { FW_CFG_ACPI_DEVICE_ID, },
753 {},
754};
755MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
756#endif
757
758static struct platform_driver fw_cfg_sysfs_driver = {
759 .probe = fw_cfg_sysfs_probe,
760 .remove_new = fw_cfg_sysfs_remove,
761 .driver = {
762 .name = "fw_cfg",
763 .of_match_table = fw_cfg_sysfs_mmio_match,
764 .acpi_match_table = ACPI_PTR(fw_cfg_sysfs_acpi_match),
765 },
766};
767
768#ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
769
770static struct platform_device *fw_cfg_cmdline_dev;
771
772/* this probably belongs in e.g. include/linux/types.h,
773 * but right now we are the only ones doing it...
774 */
775#ifdef CONFIG_PHYS_ADDR_T_64BIT
776#define __PHYS_ADDR_PREFIX "ll"
777#else
778#define __PHYS_ADDR_PREFIX ""
779#endif
780
781/* use special scanf/printf modifier for phys_addr_t, resource_size_t */
782#define PH_ADDR_SCAN_FMT "@%" __PHYS_ADDR_PREFIX "i%n" \
783 ":%" __PHYS_ADDR_PREFIX "i" \
784 ":%" __PHYS_ADDR_PREFIX "i%n" \
785 ":%" __PHYS_ADDR_PREFIX "i%n"
786
787#define PH_ADDR_PR_1_FMT "0x%" __PHYS_ADDR_PREFIX "x@" \
788 "0x%" __PHYS_ADDR_PREFIX "x"
789
790#define PH_ADDR_PR_3_FMT PH_ADDR_PR_1_FMT \
791 ":%" __PHYS_ADDR_PREFIX "u" \
792 ":%" __PHYS_ADDR_PREFIX "u"
793
794#define PH_ADDR_PR_4_FMT PH_ADDR_PR_3_FMT \
795 ":%" __PHYS_ADDR_PREFIX "u"
796
797static int fw_cfg_cmdline_set(const char *arg, const struct kernel_param *kp)
798{
799 struct resource res[4] = {};
800 char *str;
801 phys_addr_t base;
802 resource_size_t size, ctrl_off, data_off, dma_off;
803 int processed, consumed = 0;
804
805 /* only one fw_cfg device can exist system-wide, so if one
806 * was processed on the command line already, we might as
807 * well stop here.
808 */
809 if (fw_cfg_cmdline_dev) {
810 /* avoid leaking previously registered device */
811 platform_device_unregister(fw_cfg_cmdline_dev);
812 return -EINVAL;
813 }
814
815 /* consume "<size>" portion of command line argument */
816 size = memparse(ptr: arg, retptr: &str);
817
818 /* get "@<base>[:<ctrl_off>:<data_off>[:<dma_off>]]" chunks */
819 processed = sscanf(str, PH_ADDR_SCAN_FMT,
820 &base, &consumed,
821 &ctrl_off, &data_off, &consumed,
822 &dma_off, &consumed);
823
824 /* sscanf() must process precisely 1, 3 or 4 chunks:
825 * <base> is mandatory, optionally followed by <ctrl_off>
826 * and <data_off>, and <dma_off>;
827 * there must be no extra characters after the last chunk,
828 * so str[consumed] must be '\0'.
829 */
830 if (str[consumed] ||
831 (processed != 1 && processed != 3 && processed != 4))
832 return -EINVAL;
833
834 res[0].start = base;
835 res[0].end = base + size - 1;
836 res[0].flags = !strcmp(kp->name, "mmio") ? IORESOURCE_MEM :
837 IORESOURCE_IO;
838
839 /* insert register offsets, if provided */
840 if (processed > 1) {
841 res[1].name = "ctrl";
842 res[1].start = ctrl_off;
843 res[1].flags = IORESOURCE_REG;
844 res[2].name = "data";
845 res[2].start = data_off;
846 res[2].flags = IORESOURCE_REG;
847 }
848 if (processed > 3) {
849 res[3].name = "dma";
850 res[3].start = dma_off;
851 res[3].flags = IORESOURCE_REG;
852 }
853
854 /* "processed" happens to nicely match the number of resources
855 * we need to pass in to this platform device.
856 */
857 fw_cfg_cmdline_dev = platform_device_register_simple(name: "fw_cfg",
858 PLATFORM_DEVID_NONE, res, num: processed);
859
860 return PTR_ERR_OR_ZERO(ptr: fw_cfg_cmdline_dev);
861}
862
863static int fw_cfg_cmdline_get(char *buf, const struct kernel_param *kp)
864{
865 /* stay silent if device was not configured via the command
866 * line, or if the parameter name (ioport/mmio) doesn't match
867 * the device setting
868 */
869 if (!fw_cfg_cmdline_dev ||
870 (!strcmp(kp->name, "mmio") ^
871 (fw_cfg_cmdline_dev->resource[0].flags == IORESOURCE_MEM)))
872 return 0;
873
874 switch (fw_cfg_cmdline_dev->num_resources) {
875 case 1:
876 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_1_FMT,
877 resource_size(res: &fw_cfg_cmdline_dev->resource[0]),
878 fw_cfg_cmdline_dev->resource[0].start);
879 case 3:
880 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_3_FMT,
881 resource_size(res: &fw_cfg_cmdline_dev->resource[0]),
882 fw_cfg_cmdline_dev->resource[0].start,
883 fw_cfg_cmdline_dev->resource[1].start,
884 fw_cfg_cmdline_dev->resource[2].start);
885 case 4:
886 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_4_FMT,
887 resource_size(res: &fw_cfg_cmdline_dev->resource[0]),
888 fw_cfg_cmdline_dev->resource[0].start,
889 fw_cfg_cmdline_dev->resource[1].start,
890 fw_cfg_cmdline_dev->resource[2].start,
891 fw_cfg_cmdline_dev->resource[3].start);
892 }
893
894 /* Should never get here */
895 WARN(1, "Unexpected number of resources: %d\n",
896 fw_cfg_cmdline_dev->num_resources);
897 return 0;
898}
899
900static const struct kernel_param_ops fw_cfg_cmdline_param_ops = {
901 .set = fw_cfg_cmdline_set,
902 .get = fw_cfg_cmdline_get,
903};
904
905device_param_cb(ioport, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
906device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
907
908#endif /* CONFIG_FW_CFG_SYSFS_CMDLINE */
909
910static int __init fw_cfg_sysfs_init(void)
911{
912 int ret;
913
914 /* create /sys/firmware/qemu_fw_cfg/ top level directory */
915 fw_cfg_top_ko = kobject_create_and_add(name: "qemu_fw_cfg", parent: firmware_kobj);
916 if (!fw_cfg_top_ko)
917 return -ENOMEM;
918
919 ret = platform_driver_register(&fw_cfg_sysfs_driver);
920 if (ret)
921 fw_cfg_kobj_cleanup(kobj: fw_cfg_top_ko);
922
923 return ret;
924}
925
926static void __exit fw_cfg_sysfs_exit(void)
927{
928 platform_driver_unregister(&fw_cfg_sysfs_driver);
929
930#ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
931 platform_device_unregister(fw_cfg_cmdline_dev);
932#endif
933
934 /* clean up /sys/firmware/qemu_fw_cfg/ */
935 fw_cfg_kobj_cleanup(kobj: fw_cfg_top_ko);
936}
937
938module_init(fw_cfg_sysfs_init);
939module_exit(fw_cfg_sysfs_exit);
940

source code of linux/drivers/firmware/qemu_fw_cfg.c