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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 * [fw_cfg.]ioport=<size>@<base>[:<ctrl_off>:<data_off>]
14 * or
15 * [fw_cfg.]mmio=<size>@<base>[:<ctrl_off>:<data_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 *
23 * e.g.:
24 * fw_cfg.ioport=2@0x510:0:1 (the default on x86)
25 * or
26 * fw_cfg.mmio=0xA@0x9020000:8:0 (the default on arm)
27 */
28
29#include <linux/module.h>
30#include <linux/platform_device.h>
31#include <linux/acpi.h>
32#include <linux/slab.h>
33#include <linux/io.h>
34#include <linux/ioport.h>
35
36MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
37MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
38MODULE_LICENSE("GPL");
39
40/* selector key values for "well-known" fw_cfg entries */
41#define FW_CFG_SIGNATURE 0x00
42#define FW_CFG_ID 0x01
43#define FW_CFG_FILE_DIR 0x19
44
45/* size in bytes of fw_cfg signature */
46#define FW_CFG_SIG_SIZE 4
47
48/* fw_cfg "file name" is up to 56 characters (including terminating nul) */
49#define FW_CFG_MAX_FILE_PATH 56
50
51/* fw_cfg file directory entry type */
52struct fw_cfg_file {
53 u32 size;
54 u16 select;
55 u16 reserved;
56 char name[FW_CFG_MAX_FILE_PATH];
57};
58
59/* fw_cfg device i/o register addresses */
60static bool fw_cfg_is_mmio;
61static phys_addr_t fw_cfg_p_base;
62static resource_size_t fw_cfg_p_size;
63static void __iomem *fw_cfg_dev_base;
64static void __iomem *fw_cfg_reg_ctrl;
65static void __iomem *fw_cfg_reg_data;
66
67/* atomic access to fw_cfg device (potentially slow i/o, so using mutex) */
68static DEFINE_MUTEX(fw_cfg_dev_lock);
69
70/* pick appropriate endianness for selector key */
71static inline u16 fw_cfg_sel_endianness(u16 key)
72{
73 return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key);
74}
75
76/* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
77static inline void fw_cfg_read_blob(u16 key,
78 void *buf, loff_t pos, size_t count)
79{
80 u32 glk = -1U;
81 acpi_status status;
82
83 /* If we have ACPI, ensure mutual exclusion against any potential
84 * device access by the firmware, e.g. via AML methods:
85 */
86 status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
87 if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
88 /* Should never get here */
89 WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
90 memset(buf, 0, count);
91 return;
92 }
93
94 mutex_lock(&fw_cfg_dev_lock);
95 iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
96 while (pos-- > 0)
97 ioread8(fw_cfg_reg_data);
98 ioread8_rep(fw_cfg_reg_data, buf, count);
99 mutex_unlock(&fw_cfg_dev_lock);
100
101 acpi_release_global_lock(glk);
102}
103
104/* clean up fw_cfg device i/o */
105static void fw_cfg_io_cleanup(void)
106{
107 if (fw_cfg_is_mmio) {
108 iounmap(fw_cfg_dev_base);
109 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
110 } else {
111 ioport_unmap(fw_cfg_dev_base);
112 release_region(fw_cfg_p_base, fw_cfg_p_size);
113 }
114}
115
116/* arch-specific ctrl & data register offsets are not available in ACPI, DT */
117#if !(defined(FW_CFG_CTRL_OFF) && defined(FW_CFG_DATA_OFF))
118# if (defined(CONFIG_ARM) || defined(CONFIG_ARM64))
119# define FW_CFG_CTRL_OFF 0x08
120# define FW_CFG_DATA_OFF 0x00
121# elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
122# define FW_CFG_CTRL_OFF 0x00
123# define FW_CFG_DATA_OFF 0x02
124# elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */
125# define FW_CFG_CTRL_OFF 0x00
126# define FW_CFG_DATA_OFF 0x01
127# else
128# warning "QEMU FW_CFG may not be available on this architecture!"
129# define FW_CFG_CTRL_OFF 0x00
130# define FW_CFG_DATA_OFF 0x01
131# endif
132#endif
133
134/* initialize fw_cfg device i/o from platform data */
135static int fw_cfg_do_platform_probe(struct platform_device *pdev)
136{
137 char sig[FW_CFG_SIG_SIZE];
138 struct resource *range, *ctrl, *data;
139
140 /* acquire i/o range details */
141 fw_cfg_is_mmio = false;
142 range = platform_get_resource(pdev, IORESOURCE_IO, 0);
143 if (!range) {
144 fw_cfg_is_mmio = true;
145 range = platform_get_resource(pdev, IORESOURCE_MEM, 0);
146 if (!range)
147 return -EINVAL;
148 }
149 fw_cfg_p_base = range->start;
150 fw_cfg_p_size = resource_size(range);
151
152 if (fw_cfg_is_mmio) {
153 if (!request_mem_region(fw_cfg_p_base,
154 fw_cfg_p_size, "fw_cfg_mem"))
155 return -EBUSY;
156 fw_cfg_dev_base = ioremap(fw_cfg_p_base, fw_cfg_p_size);
157 if (!fw_cfg_dev_base) {
158 release_mem_region(fw_cfg_p_base, fw_cfg_p_size);
159 return -EFAULT;
160 }
161 } else {
162 if (!request_region(fw_cfg_p_base,
163 fw_cfg_p_size, "fw_cfg_io"))
164 return -EBUSY;
165 fw_cfg_dev_base = ioport_map(fw_cfg_p_base, fw_cfg_p_size);
166 if (!fw_cfg_dev_base) {
167 release_region(fw_cfg_p_base, fw_cfg_p_size);
168 return -EFAULT;
169 }
170 }
171
172 /* were custom register offsets provided (e.g. on the command line)? */
173 ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");
174 data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");
175 if (ctrl && data) {
176 fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;
177 fw_cfg_reg_data = fw_cfg_dev_base + data->start;
178 } else {
179 /* use architecture-specific offsets */
180 fw_cfg_reg_ctrl = fw_cfg_dev_base + FW_CFG_CTRL_OFF;
181 fw_cfg_reg_data = fw_cfg_dev_base + FW_CFG_DATA_OFF;
182 }
183
184 /* verify fw_cfg device signature */
185 fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE);
186 if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
187 fw_cfg_io_cleanup();
188 return -ENODEV;
189 }
190
191 return 0;
192}
193
194/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
195static u32 fw_cfg_rev;
196
197static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
198{
199 return sprintf(buf, "%u\n", fw_cfg_rev);
200}
201
202static const struct {
203 struct attribute attr;
204 ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);
205} fw_cfg_rev_attr = {
206 .attr = { .name = "rev", .mode = S_IRUSR },
207 .show = fw_cfg_showrev,
208};
209
210/* fw_cfg_sysfs_entry type */
211struct fw_cfg_sysfs_entry {
212 struct kobject kobj;
213 struct fw_cfg_file f;
214 struct list_head list;
215};
216
217/* get fw_cfg_sysfs_entry from kobject member */
218static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
219{
220 return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);
221}
222
223/* fw_cfg_sysfs_attribute type */
224struct fw_cfg_sysfs_attribute {
225 struct attribute attr;
226 ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);
227};
228
229/* get fw_cfg_sysfs_attribute from attribute member */
230static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)
231{
232 return container_of(attr, struct fw_cfg_sysfs_attribute, attr);
233}
234
235/* global cache of fw_cfg_sysfs_entry objects */
236static LIST_HEAD(fw_cfg_entry_cache);
237
238/* kobjects removed lazily by kernel, mutual exclusion needed */
239static DEFINE_SPINLOCK(fw_cfg_cache_lock);
240
241static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)
242{
243 spin_lock(&fw_cfg_cache_lock);
244 list_add_tail(&entry->list, &fw_cfg_entry_cache);
245 spin_unlock(&fw_cfg_cache_lock);
246}
247
248static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)
249{
250 spin_lock(&fw_cfg_cache_lock);
251 list_del(&entry->list);
252 spin_unlock(&fw_cfg_cache_lock);
253}
254
255static void fw_cfg_sysfs_cache_cleanup(void)
256{
257 struct fw_cfg_sysfs_entry *entry, *next;
258
259 list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {
260 /* will end up invoking fw_cfg_sysfs_cache_delist()
261 * via each object's release() method (i.e. destructor)
262 */
263 kobject_put(&entry->kobj);
264 }
265}
266
267/* default_attrs: per-entry attributes and show methods */
268
269#define FW_CFG_SYSFS_ATTR(_attr) \
270struct fw_cfg_sysfs_attribute fw_cfg_sysfs_attr_##_attr = { \
271 .attr = { .name = __stringify(_attr), .mode = S_IRUSR }, \
272 .show = fw_cfg_sysfs_show_##_attr, \
273}
274
275static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)
276{
277 return sprintf(buf, "%u\n", e->f.size);
278}
279
280static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)
281{
282 return sprintf(buf, "%u\n", e->f.select);
283}
284
285static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)
286{
287 return sprintf(buf, "%s\n", e->f.name);
288}
289
290static FW_CFG_SYSFS_ATTR(size);
291static FW_CFG_SYSFS_ATTR(key);
292static FW_CFG_SYSFS_ATTR(name);
293
294static struct attribute *fw_cfg_sysfs_entry_attrs[] = {
295 &fw_cfg_sysfs_attr_size.attr,
296 &fw_cfg_sysfs_attr_key.attr,
297 &fw_cfg_sysfs_attr_name.attr,
298 NULL,
299};
300
301/* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */
302static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,
303 char *buf)
304{
305 struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
306 struct fw_cfg_sysfs_attribute *attr = to_attr(a);
307
308 return attr->show(entry, buf);
309}
310
311static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {
312 .show = fw_cfg_sysfs_attr_show,
313};
314
315/* release: destructor, to be called via kobject_put() */
316static void fw_cfg_sysfs_release_entry(struct kobject *kobj)
317{
318 struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
319
320 fw_cfg_sysfs_cache_delist(entry);
321 kfree(entry);
322}
323
324/* kobj_type: ties together all properties required to register an entry */
325static struct kobj_type fw_cfg_sysfs_entry_ktype = {
326 .default_attrs = fw_cfg_sysfs_entry_attrs,
327 .sysfs_ops = &fw_cfg_sysfs_attr_ops,
328 .release = fw_cfg_sysfs_release_entry,
329};
330
331/* raw-read method and attribute */
332static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
333 struct bin_attribute *bin_attr,
334 char *buf, loff_t pos, size_t count)
335{
336 struct fw_cfg_sysfs_entry *entry = to_entry(kobj);
337
338 if (pos > entry->f.size)
339 return -EINVAL;
340
341 if (count > entry->f.size - pos)
342 count = entry->f.size - pos;
343
344 fw_cfg_read_blob(entry->f.select, buf, pos, count);
345 return count;
346}
347
348static struct bin_attribute fw_cfg_sysfs_attr_raw = {
349 .attr = { .name = "raw", .mode = S_IRUSR },
350 .read = fw_cfg_sysfs_read_raw,
351};
352
353/*
354 * Create a kset subdirectory matching each '/' delimited dirname token
355 * in 'name', starting with sysfs kset/folder 'dir'; At the end, create
356 * a symlink directed at the given 'target'.
357 * NOTE: We do this on a best-effort basis, since 'name' is not guaranteed
358 * to be a well-behaved path name. Whenever a symlink vs. kset directory
359 * name collision occurs, the kernel will issue big scary warnings while
360 * refusing to add the offending link or directory. We follow up with our
361 * own, slightly less scary error messages explaining the situation :)
362 */
363static int fw_cfg_build_symlink(struct kset *dir,
364 struct kobject *target, const char *name)
365{
366 int ret;
367 struct kset *subdir;
368 struct kobject *ko;
369 char *name_copy, *p, *tok;
370
371 if (!dir || !target || !name || !*name)
372 return -EINVAL;
373
374 /* clone a copy of name for parsing */
375 name_copy = p = kstrdup(name, GFP_KERNEL);
376 if (!name_copy)
377 return -ENOMEM;
378
379 /* create folders for each dirname token, then symlink for basename */
380 while ((tok = strsep(&p, "/")) && *tok) {
381
382 /* last (basename) token? If so, add symlink here */
383 if (!p || !*p) {
384 ret = sysfs_create_link(&dir->kobj, target, tok);
385 break;
386 }
387
388 /* does the current dir contain an item named after tok ? */
389 ko = kset_find_obj(dir, tok);
390 if (ko) {
391 /* drop reference added by kset_find_obj */
392 kobject_put(ko);
393
394 /* ko MUST be a kset - we're about to use it as one ! */
395 if (ko->ktype != dir->kobj.ktype) {
396 ret = -EINVAL;
397 break;
398 }
399
400 /* descend into already existing subdirectory */
401 dir = to_kset(ko);
402 } else {
403 /* create new subdirectory kset */
404 subdir = kzalloc(sizeof(struct kset), GFP_KERNEL);
405 if (!subdir) {
406 ret = -ENOMEM;
407 break;
408 }
409 subdir->kobj.kset = dir;
410 subdir->kobj.ktype = dir->kobj.ktype;
411 ret = kobject_set_name(&subdir->kobj, "%s", tok);
412 if (ret) {
413 kfree(subdir);
414 break;
415 }
416 ret = kset_register(subdir);
417 if (ret) {
418 kfree(subdir);
419 break;
420 }
421
422 /* descend into newly created subdirectory */
423 dir = subdir;
424 }
425 }
426
427 /* we're done with cloned copy of name */
428 kfree(name_copy);
429 return ret;
430}
431
432/* recursively unregister fw_cfg/by_name/ kset directory tree */
433static void fw_cfg_kset_unregister_recursive(struct kset *kset)
434{
435 struct kobject *k, *next;
436
437 list_for_each_entry_safe(k, next, &kset->list, entry)
438 /* all set members are ksets too, but check just in case... */
439 if (k->ktype == kset->kobj.ktype)
440 fw_cfg_kset_unregister_recursive(to_kset(k));
441
442 /* symlinks are cleanly and automatically removed with the directory */
443 kset_unregister(kset);
444}
445
446/* kobjects & kset representing top-level, by_key, and by_name folders */
447static struct kobject *fw_cfg_top_ko;
448static struct kobject *fw_cfg_sel_ko;
449static struct kset *fw_cfg_fname_kset;
450
451/* register an individual fw_cfg file */
452static int fw_cfg_register_file(const struct fw_cfg_file *f)
453{
454 int err;
455 struct fw_cfg_sysfs_entry *entry;
456
457 /* allocate new entry */
458 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
459 if (!entry)
460 return -ENOMEM;
461
462 /* set file entry information */
463 memcpy(&entry->f, f, sizeof(struct fw_cfg_file));
464
465 /* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */
466 err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,
467 fw_cfg_sel_ko, "%d", entry->f.select);
468 if (err)
469 goto err_register;
470
471 /* add raw binary content access */
472 err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);
473 if (err)
474 goto err_add_raw;
475
476 /* try adding "/sys/firmware/qemu_fw_cfg/by_name/" symlink */
477 fw_cfg_build_symlink(fw_cfg_fname_kset, &entry->kobj, entry->f.name);
478
479 /* success, add entry to global cache */
480 fw_cfg_sysfs_cache_enlist(entry);
481 return 0;
482
483err_add_raw:
484 kobject_del(&entry->kobj);
485err_register:
486 kfree(entry);
487 return err;
488}
489
490/* iterate over all fw_cfg directory entries, registering each one */
491static int fw_cfg_register_dir_entries(void)
492{
493 int ret = 0;
494 u32 count, i;
495 struct fw_cfg_file *dir;
496 size_t dir_size;
497
498 fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count));
499 count = be32_to_cpu(count);
500 dir_size = count * sizeof(struct fw_cfg_file);
501
502 dir = kmalloc(dir_size, GFP_KERNEL);
503 if (!dir)
504 return -ENOMEM;
505
506 fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size);
507
508 for (i = 0; i < count; i++) {
509 dir[i].size = be32_to_cpu(dir[i].size);
510 dir[i].select = be16_to_cpu(dir[i].select);
511 ret = fw_cfg_register_file(&dir[i]);
512 if (ret)
513 break;
514 }
515
516 kfree(dir);
517 return ret;
518}
519
520/* unregister top-level or by_key folder */
521static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)
522{
523 kobject_del(kobj);
524 kobject_put(kobj);
525}
526
527static int fw_cfg_sysfs_probe(struct platform_device *pdev)
528{
529 int err;
530
531 /* NOTE: If we supported multiple fw_cfg devices, we'd first create
532 * a subdirectory named after e.g. pdev->id, then hang per-device
533 * by_key (and by_name) subdirectories underneath it. However, only
534 * one fw_cfg device exist system-wide, so if one was already found
535 * earlier, we might as well stop here.
536 */
537 if (fw_cfg_sel_ko)
538 return -EBUSY;
539
540 /* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
541 err = -ENOMEM;
542 fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
543 if (!fw_cfg_sel_ko)
544 goto err_sel;
545 fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
546 if (!fw_cfg_fname_kset)
547 goto err_name;
548
549 /* initialize fw_cfg device i/o from platform data */
550 err = fw_cfg_do_platform_probe(pdev);
551 if (err)
552 goto err_probe;
553
554 /* get revision number, add matching top-level attribute */
555 fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev));
556 fw_cfg_rev = le32_to_cpu(fw_cfg_rev);
557 err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
558 if (err)
559 goto err_rev;
560
561 /* process fw_cfg file directory entry, registering each file */
562 err = fw_cfg_register_dir_entries();
563 if (err)
564 goto err_dir;
565
566 /* success */
567 pr_debug("fw_cfg: loaded.\n");
568 return 0;
569
570err_dir:
571 fw_cfg_sysfs_cache_cleanup();
572 sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
573err_rev:
574 fw_cfg_io_cleanup();
575err_probe:
576 fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
577err_name:
578 fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
579err_sel:
580 return err;
581}
582
583static int fw_cfg_sysfs_remove(struct platform_device *pdev)
584{
585 pr_debug("fw_cfg: unloading.\n");
586 fw_cfg_sysfs_cache_cleanup();
587 fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
588 fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
589 fw_cfg_io_cleanup();
590 return 0;
591}
592
593static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
594 { .compatible = "qemu,fw-cfg-mmio", },
595 {},
596};
597MODULE_DEVICE_TABLE(of, fw_cfg_sysfs_mmio_match);
598
599#ifdef CONFIG_ACPI
600static const struct acpi_device_id fw_cfg_sysfs_acpi_match[] = {
601 { "QEMU0002", },
602 {},
603};
604MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
605#endif
606
607static struct platform_driver fw_cfg_sysfs_driver = {
608 .probe = fw_cfg_sysfs_probe,
609 .remove = fw_cfg_sysfs_remove,
610 .driver = {
611 .name = "fw_cfg",
612 .of_match_table = fw_cfg_sysfs_mmio_match,
613 .acpi_match_table = ACPI_PTR(fw_cfg_sysfs_acpi_match),
614 },
615};
616
617#ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
618
619static struct platform_device *fw_cfg_cmdline_dev;
620
621/* this probably belongs in e.g. include/linux/types.h,
622 * but right now we are the only ones doing it...
623 */
624#ifdef CONFIG_PHYS_ADDR_T_64BIT
625#define __PHYS_ADDR_PREFIX "ll"
626#else
627#define __PHYS_ADDR_PREFIX ""
628#endif
629
630/* use special scanf/printf modifier for phys_addr_t, resource_size_t */
631#define PH_ADDR_SCAN_FMT "@%" __PHYS_ADDR_PREFIX "i%n" \
632 ":%" __PHYS_ADDR_PREFIX "i" \
633 ":%" __PHYS_ADDR_PREFIX "i%n"
634
635#define PH_ADDR_PR_1_FMT "0x%" __PHYS_ADDR_PREFIX "x@" \
636 "0x%" __PHYS_ADDR_PREFIX "x"
637
638#define PH_ADDR_PR_3_FMT PH_ADDR_PR_1_FMT \
639 ":%" __PHYS_ADDR_PREFIX "u" \
640 ":%" __PHYS_ADDR_PREFIX "u"
641
642static int fw_cfg_cmdline_set(const char *arg, const struct kernel_param *kp)
643{
644 struct resource res[3] = {};
645 char *str;
646 phys_addr_t base;
647 resource_size_t size, ctrl_off, data_off;
648 int processed, consumed = 0;
649
650 /* only one fw_cfg device can exist system-wide, so if one
651 * was processed on the command line already, we might as
652 * well stop here.
653 */
654 if (fw_cfg_cmdline_dev) {
655 /* avoid leaking previously registered device */
656 platform_device_unregister(fw_cfg_cmdline_dev);
657 return -EINVAL;
658 }
659
660 /* consume "<size>" portion of command line argument */
661 size = memparse(arg, &str);
662
663 /* get "@<base>[:<ctrl_off>:<data_off>]" chunks */
664 processed = sscanf(str, PH_ADDR_SCAN_FMT,
665 &base, &consumed,
666 &ctrl_off, &data_off, &consumed);
667
668 /* sscanf() must process precisely 1 or 3 chunks:
669 * <base> is mandatory, optionally followed by <ctrl_off>
670 * and <data_off>;
671 * there must be no extra characters after the last chunk,
672 * so str[consumed] must be '\0'.
673 */
674 if (str[consumed] ||
675 (processed != 1 && processed != 3))
676 return -EINVAL;
677
678 res[0].start = base;
679 res[0].end = base + size - 1;
680 res[0].flags = !strcmp(kp->name, "mmio") ? IORESOURCE_MEM :
681 IORESOURCE_IO;
682
683 /* insert register offsets, if provided */
684 if (processed > 1) {
685 res[1].name = "ctrl";
686 res[1].start = ctrl_off;
687 res[1].flags = IORESOURCE_REG;
688 res[2].name = "data";
689 res[2].start = data_off;
690 res[2].flags = IORESOURCE_REG;
691 }
692
693 /* "processed" happens to nicely match the number of resources
694 * we need to pass in to this platform device.
695 */
696 fw_cfg_cmdline_dev = platform_device_register_simple("fw_cfg",
697 PLATFORM_DEVID_NONE, res, processed);
698 if (IS_ERR(fw_cfg_cmdline_dev))
699 return PTR_ERR(fw_cfg_cmdline_dev);
700
701 return 0;
702}
703
704static int fw_cfg_cmdline_get(char *buf, const struct kernel_param *kp)
705{
706 /* stay silent if device was not configured via the command
707 * line, or if the parameter name (ioport/mmio) doesn't match
708 * the device setting
709 */
710 if (!fw_cfg_cmdline_dev ||
711 (!strcmp(kp->name, "mmio") ^
712 (fw_cfg_cmdline_dev->resource[0].flags == IORESOURCE_MEM)))
713 return 0;
714
715 switch (fw_cfg_cmdline_dev->num_resources) {
716 case 1:
717 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_1_FMT,
718 resource_size(&fw_cfg_cmdline_dev->resource[0]),
719 fw_cfg_cmdline_dev->resource[0].start);
720 case 3:
721 return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_3_FMT,
722 resource_size(&fw_cfg_cmdline_dev->resource[0]),
723 fw_cfg_cmdline_dev->resource[0].start,
724 fw_cfg_cmdline_dev->resource[1].start,
725 fw_cfg_cmdline_dev->resource[2].start);
726 }
727
728 /* Should never get here */
729 WARN(1, "Unexpected number of resources: %d\n",
730 fw_cfg_cmdline_dev->num_resources);
731 return 0;
732}
733
734static const struct kernel_param_ops fw_cfg_cmdline_param_ops = {
735 .set = fw_cfg_cmdline_set,
736 .get = fw_cfg_cmdline_get,
737};
738
739device_param_cb(ioport, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
740device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);
741
742#endif /* CONFIG_FW_CFG_SYSFS_CMDLINE */
743
744static int __init fw_cfg_sysfs_init(void)
745{
746 int ret;
747
748 /* create /sys/firmware/qemu_fw_cfg/ top level directory */
749 fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);
750 if (!fw_cfg_top_ko)
751 return -ENOMEM;
752
753 ret = platform_driver_register(&fw_cfg_sysfs_driver);
754 if (ret)
755 fw_cfg_kobj_cleanup(fw_cfg_top_ko);
756
757 return ret;
758}
759
760static void __exit fw_cfg_sysfs_exit(void)
761{
762 platform_driver_unregister(&fw_cfg_sysfs_driver);
763
764#ifdef CONFIG_FW_CFG_SYSFS_CMDLINE
765 platform_device_unregister(fw_cfg_cmdline_dev);
766#endif
767
768 /* clean up /sys/firmware/qemu_fw_cfg/ */
769 fw_cfg_kobj_cleanup(fw_cfg_top_ko);
770}
771
772module_init(fw_cfg_sysfs_init);
773module_exit(fw_cfg_sysfs_exit);