1// SPDX-License-Identifier: GPL-2.0-only
   2/* 
   3 *    Interfaces to retrieve and set PDC Stable options (firmware)
   4 *
   5 *    Copyright (C) 2005-2006 Thibaut VARENE <varenet@parisc-linux.org>
   6 *
   7 *    DEV NOTE: the PDC Procedures reference states that:
   8 *    "A minimum of 96 bytes of Stable Storage is required. Providing more than
   9 *    96 bytes of Stable Storage is optional [...]. Failure to provide the
  10 *    optional locations from 96 to 192 results in the loss of certain
  11 *    functionality during boot."
  12 *
  13 *    Since locations between 96 and 192 are the various paths, most (if not
  14 *    all) PA-RISC machines should have them. Anyway, for safety reasons, the
  15 *    following code can deal with just 96 bytes of Stable Storage, and all
  16 *    sizes between 96 and 192 bytes (provided they are multiple of struct
  17 *    pdc_module_path size, eg: 128, 160 and 192) to provide full information.
  18 *    One last word: there's one path we can always count on: the primary path.
  19 *    Anything above 224 bytes is used for 'osdep2' OS-dependent storage area.
  20 *
  21 *    The first OS-dependent area should always be available. Obviously, this is
  22 *    not true for the other one. Also bear in mind that reading/writing from/to
  23 *    osdep2 is much more expensive than from/to osdep1.
  24 *    NOTE: We do not handle the 2 bytes OS-dep area at 0x5D, nor the first
  25 *    2 bytes of storage available right after OSID. That's a total of 4 bytes
  26 *    sacrificed: -ETOOLAZY :P
  27 *
  28 *    The current policy wrt file permissions is:
  29 *	- write: root only
  30 *	- read: (reading triggers PDC calls) ? root only : everyone
  31 *    The rationale is that PDC calls could hog (DoS) the machine.
  32 *
  33 *	TODO:
  34 *	- timer/fastsize write calls
  35 */
  36
  37#undef PDCS_DEBUG
  38#ifdef PDCS_DEBUG
  39#define DPRINTK(fmt, args...)	printk(KERN_DEBUG fmt, ## args)
  40#else
  41#define DPRINTK(fmt, args...)
  42#endif
  43
  44#include <linux/module.h>
  45#include <linux/init.h>
  46#include <linux/kernel.h>
  47#include <linux/string.h>
  48#include <linux/capability.h>
  49#include <linux/ctype.h>
  50#include <linux/sysfs.h>
  51#include <linux/kobject.h>
  52#include <linux/device.h>
  53#include <linux/errno.h>
  54#include <linux/spinlock.h>
  55
  56#include <asm/pdc.h>
  57#include <asm/page.h>
  58#include <linux/uaccess.h>
  59#include <asm/hardware.h>
  60
  61#define PDCS_VERSION	"0.30"
  62#define PDCS_PREFIX	"PDC Stable Storage"
  63
  64#define PDCS_ADDR_PPRI	0x00
  65#define PDCS_ADDR_OSID	0x40
  66#define PDCS_ADDR_OSD1	0x48
  67#define PDCS_ADDR_DIAG	0x58
  68#define PDCS_ADDR_FSIZ	0x5C
  69#define PDCS_ADDR_PCON	0x60
  70#define PDCS_ADDR_PALT	0x80
  71#define PDCS_ADDR_PKBD	0xA0
  72#define PDCS_ADDR_OSD2	0xE0
  73
  74MODULE_AUTHOR("Thibaut VARENE <varenet@parisc-linux.org>");
  75MODULE_DESCRIPTION("sysfs interface to HP PDC Stable Storage data");
  76MODULE_LICENSE("GPL");
  77MODULE_VERSION(PDCS_VERSION);
  78
  79/* holds Stable Storage size. Initialized once and for all, no lock needed */
  80static unsigned long pdcs_size __read_mostly;
  81
  82/* holds OS ID. Initialized once and for all, hopefully to 0x0006 */
  83static u16 pdcs_osid __read_mostly;
  84
  85/* This struct defines what we need to deal with a parisc pdc path entry */
  86struct pdcspath_entry {
  87	rwlock_t rw_lock;		/* to protect path entry access */
  88	short ready;			/* entry record is valid if != 0 */
  89	unsigned long addr;		/* entry address in stable storage */
  90	char *name;			/* entry name */
  91	struct pdc_module_path devpath;	/* device path in parisc representation */
  92	struct device *dev;		/* corresponding device */
  93	struct kobject kobj;
  94};
  95
  96struct pdcspath_attribute {
  97	struct attribute attr;
  98	ssize_t (*show)(struct pdcspath_entry *entry, char *buf);
  99	ssize_t (*store)(struct pdcspath_entry *entry, const char *buf, size_t count);
 100};
 101
 102#define PDCSPATH_ENTRY(_addr, _name) \
 103struct pdcspath_entry pdcspath_entry_##_name = { \
 104	.ready = 0, \
 105	.addr = _addr, \
 106	.name = __stringify(_name), \
 107};
 108
 109#define PDCS_ATTR(_name, _mode, _show, _store) \
 110struct kobj_attribute pdcs_attr_##_name = { \
 111	.attr = {.name = __stringify(_name), .mode = _mode}, \
 112	.show = _show, \
 113	.store = _store, \
 114};
 115
 116#define PATHS_ATTR(_name, _mode, _show, _store) \
 117struct pdcspath_attribute paths_attr_##_name = { \
 118	.attr = {.name = __stringify(_name), .mode = _mode}, \
 119	.show = _show, \
 120	.store = _store, \
 121};
 122
 123#define to_pdcspath_attribute(_attr) container_of(_attr, struct pdcspath_attribute, attr)
 124#define to_pdcspath_entry(obj)  container_of(obj, struct pdcspath_entry, kobj)
 125
 126/**
 127 * pdcspath_fetch - This function populates the path entry structs.
 128 * @entry: A pointer to an allocated pdcspath_entry.
 129 * 
 130 * The general idea is that you don't read from the Stable Storage every time
 131 * you access the files provided by the facilities. We store a copy of the
 132 * content of the stable storage WRT various paths in these structs. We read
 133 * these structs when reading the files, and we will write to these structs when
 134 * writing to the files, and only then write them back to the Stable Storage.
 135 *
 136 * This function expects to be called with @entry->rw_lock write-hold.
 137 */
 138static int
 139pdcspath_fetch(struct pdcspath_entry *entry)
 140{
 141	struct pdc_module_path *devpath;
 142
 143	if (!entry)
 144		return -EINVAL;
 145
 146	devpath = &entry->devpath;
 147	
 148	DPRINTK("%s: fetch: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
 149			entry, devpath, entry->addr);
 150
 151	/* addr, devpath and count must be word aligned */
 152	if (pdc_stable_read(entry->addr, devpath, sizeof(*devpath)) != PDC_OK)
 153		return -EIO;
 154		
 155	/* Find the matching device.
 156	   NOTE: hardware_path overlays with pdc_module_path, so the nice cast can
 157	   be used */
 158	entry->dev = hwpath_to_device((struct hardware_path *)devpath);
 159
 160	entry->ready = 1;
 161	
 162	DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
 163	
 164	return 0;
 165}
 166
 167/**
 168 * pdcspath_store - This function writes a path to stable storage.
 169 * @entry: A pointer to an allocated pdcspath_entry.
 170 * 
 171 * It can be used in two ways: either by passing it a preset devpath struct
 172 * containing an already computed hardware path, or by passing it a device
 173 * pointer, from which it'll find out the corresponding hardware path.
 174 * For now we do not handle the case where there's an error in writing to the
 175 * Stable Storage area, so you'd better not mess up the data :P
 176 *
 177 * This function expects to be called with @entry->rw_lock write-hold.
 178 */
 179static void
 180pdcspath_store(struct pdcspath_entry *entry)
 181{
 182	struct pdc_module_path *devpath;
 183
 184	BUG_ON(!entry);
 185
 186	devpath = &entry->devpath;
 187	
 188	/* We expect the caller to set the ready flag to 0 if the hardware
 189	   path struct provided is invalid, so that we know we have to fill it.
 190	   First case, we don't have a preset hwpath... */
 191	if (!entry->ready) {
 192		/* ...but we have a device, map it */
 193		BUG_ON(!entry->dev);
 194		device_to_hwpath(entry->dev, (struct hardware_path *)devpath);
 195	}
 196	/* else, we expect the provided hwpath to be valid. */
 197	
 198	DPRINTK("%s: store: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
 199			entry, devpath, entry->addr);
 200
 201	/* addr, devpath and count must be word aligned */
 202	if (pdc_stable_write(entry->addr, devpath, sizeof(*devpath)) != PDC_OK)
 203		WARN(1, KERN_ERR "%s: an error occurred when writing to PDC.\n"
 204				"It is likely that the Stable Storage data has been corrupted.\n"
 205				"Please check it carefully upon next reboot.\n", __func__);
 206		
 207	/* kobject is already registered */
 208	entry->ready = 2;
 209	
 210	DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
 211}
 212
 213/**
 214 * pdcspath_hwpath_read - This function handles hardware path pretty printing.
 215 * @entry: An allocated and populated pdscpath_entry struct.
 216 * @buf: The output buffer to write to.
 217 * 
 218 * We will call this function to format the output of the hwpath attribute file.
 219 */
 220static ssize_t
 221pdcspath_hwpath_read(struct pdcspath_entry *entry, char *buf)
 222{
 223	char *out = buf;
 224	struct pdc_module_path *devpath;
 225	short i;
 226
 227	if (!entry || !buf)
 228		return -EINVAL;
 229
 230	read_lock(&entry->rw_lock);
 231	devpath = &entry->devpath;
 232	i = entry->ready;
 233	read_unlock(&entry->rw_lock);
 234
 235	if (!i)	/* entry is not ready */
 236		return -ENODATA;
 237	
 238	for (i = 0; i < 6; i++) {
 239		if (devpath->path.bc[i] < 0)
 240			continue;
 241		out += sprintf(out, "%d/", devpath->path.bc[i]);
 242	}
 243	out += sprintf(out, "%u\n", (unsigned char)devpath->path.mod);
 244	
 245	return out - buf;
 246}
 247
 248/**
 249 * pdcspath_hwpath_write - This function handles hardware path modifying.
 250 * @entry: An allocated and populated pdscpath_entry struct.
 251 * @buf: The input buffer to read from.
 252 * @count: The number of bytes to be read.
 253 * 
 254 * We will call this function to change the current hardware path.
 255 * Hardware paths are to be given '/'-delimited, without brackets.
 256 * We make sure that the provided path actually maps to an existing
 257 * device, BUT nothing would prevent some foolish user to set the path to some
 258 * PCI bridge or even a CPU...
 259 * A better work around would be to make sure we are at the end of a device tree
 260 * for instance, but it would be IMHO beyond the simple scope of that driver.
 261 * The aim is to provide a facility. Data correctness is left to userland.
 262 */
 263static ssize_t
 264pdcspath_hwpath_write(struct pdcspath_entry *entry, const char *buf, size_t count)
 265{
 266	struct hardware_path hwpath;
 267	unsigned short i;
 268	char in[64], *temp;
 269	struct device *dev;
 270	int ret;
 271
 272	if (!entry || !buf || !count)
 273		return -EINVAL;
 274
 275	/* We'll use a local copy of buf */
 276	count = min_t(size_t, count, sizeof(in)-1);
 277	strscpy(in, buf, count + 1);
 
 278	
 279	/* Let's clean up the target. 0xff is a blank pattern */
 280	memset(&hwpath, 0xff, sizeof(hwpath));
 281	
 282	/* First, pick the mod field (the last one of the input string) */
 283	if (!(temp = strrchr(in, '/')))
 284		return -EINVAL;
 285			
 286	hwpath.mod = simple_strtoul(temp+1, NULL, 10);
 287	in[temp-in] = '\0';	/* truncate the remaining string. just precaution */
 288	DPRINTK("%s: mod: %d\n", __func__, hwpath.mod);
 289	
 290	/* Then, loop for each delimiter, making sure we don't have too many.
 291	   we write the bc fields in a down-top way. No matter what, we stop
 292	   before writing the last field. If there are too many fields anyway,
 293	   then the user is a moron and it'll be caught up later when we'll
 294	   check the consistency of the given hwpath. */
 295	for (i=5; ((temp = strrchr(in, '/'))) && (temp-in > 0) && (likely(i)); i--) {
 296		hwpath.bc[i] = simple_strtoul(temp+1, NULL, 10);
 297		in[temp-in] = '\0';
 298		DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.path.bc[i]);
 299	}
 300	
 301	/* Store the final field */		
 302	hwpath.bc[i] = simple_strtoul(in, NULL, 10);
 303	DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.path.bc[i]);
 304	
 305	/* Now we check that the user isn't trying to lure us */
 306	if (!(dev = hwpath_to_device((struct hardware_path *)&hwpath))) {
 307		printk(KERN_WARNING "%s: attempt to set invalid \"%s\" "
 308			"hardware path: %s\n", __func__, entry->name, buf);
 309		return -EINVAL;
 310	}
 311	
 312	/* So far so good, let's get in deep */
 313	write_lock(&entry->rw_lock);
 314	entry->ready = 0;
 315	entry->dev = dev;
 316	
 317	/* Now, dive in. Write back to the hardware */
 318	pdcspath_store(entry);
 319	
 320	/* Update the symlink to the real device */
 321	sysfs_remove_link(&entry->kobj, "device");
 322	write_unlock(&entry->rw_lock);
 323
 324	ret = sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
 325	WARN_ON(ret);
 326
 327	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" path to \"%s\"\n",
 328		entry->name, buf);
 329	
 330	return count;
 331}
 332
 333/**
 334 * pdcspath_layer_read - Extended layer (eg. SCSI ids) pretty printing.
 335 * @entry: An allocated and populated pdscpath_entry struct.
 336 * @buf: The output buffer to write to.
 337 * 
 338 * We will call this function to format the output of the layer attribute file.
 339 */
 340static ssize_t
 341pdcspath_layer_read(struct pdcspath_entry *entry, char *buf)
 342{
 343	char *out = buf;
 344	struct pdc_module_path *devpath;
 345	short i;
 346
 347	if (!entry || !buf)
 348		return -EINVAL;
 349	
 350	read_lock(&entry->rw_lock);
 351	devpath = &entry->devpath;
 352	i = entry->ready;
 353	read_unlock(&entry->rw_lock);
 354
 355	if (!i)	/* entry is not ready */
 356		return -ENODATA;
 357	
 358	for (i = 0; i < 6 && devpath->layers[i]; i++)
 359		out += sprintf(out, "%u ", devpath->layers[i]);
 360
 361	out += sprintf(out, "\n");
 362	
 363	return out - buf;
 364}
 365
 366/**
 367 * pdcspath_layer_write - This function handles extended layer modifying.
 368 * @entry: An allocated and populated pdscpath_entry struct.
 369 * @buf: The input buffer to read from.
 370 * @count: The number of bytes to be read.
 371 * 
 372 * We will call this function to change the current layer value.
 373 * Layers are to be given '.'-delimited, without brackets.
 374 * XXX beware we are far less checky WRT input data provided than for hwpath.
 375 * Potential harm can be done, since there's no way to check the validity of
 376 * the layer fields.
 377 */
 378static ssize_t
 379pdcspath_layer_write(struct pdcspath_entry *entry, const char *buf, size_t count)
 380{
 381	unsigned int layers[6]; /* device-specific info (ctlr#, unit#, ...) */
 382	unsigned short i;
 383	char in[64], *temp;
 384
 385	if (!entry || !buf || !count)
 386		return -EINVAL;
 387
 388	/* We'll use a local copy of buf */
 389	count = min_t(size_t, count, sizeof(in)-1);
 390	strscpy(in, buf, count + 1);
 
 391	
 392	/* Let's clean up the target. 0 is a blank pattern */
 393	memset(&layers, 0, sizeof(layers));
 394	
 395	/* First, pick the first layer */
 396	if (unlikely(!isdigit(*in)))
 397		return -EINVAL;
 398	layers[0] = simple_strtoul(in, NULL, 10);
 399	DPRINTK("%s: layer[0]: %d\n", __func__, layers[0]);
 400	
 401	temp = in;
 402	for (i=1; ((temp = strchr(temp, '.'))) && (likely(i<6)); i++) {
 403		if (unlikely(!isdigit(*(++temp))))
 404			return -EINVAL;
 405		layers[i] = simple_strtoul(temp, NULL, 10);
 406		DPRINTK("%s: layer[%d]: %d\n", __func__, i, layers[i]);
 407	}
 408		
 409	/* So far so good, let's get in deep */
 410	write_lock(&entry->rw_lock);
 411	
 412	/* First, overwrite the current layers with the new ones, not touching
 413	   the hardware path. */
 414	memcpy(&entry->devpath.layers, &layers, sizeof(layers));
 415	
 416	/* Now, dive in. Write back to the hardware */
 417	pdcspath_store(entry);
 418	write_unlock(&entry->rw_lock);
 419	
 420	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" layers to \"%s\"\n",
 421		entry->name, buf);
 422	
 423	return count;
 424}
 425
 426/**
 427 * pdcspath_attr_show - Generic read function call wrapper.
 428 * @kobj: The kobject to get info from.
 429 * @attr: The attribute looked upon.
 430 * @buf: The output buffer.
 431 */
 432static ssize_t
 433pdcspath_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
 434{
 435	struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
 436	struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
 437	ssize_t ret = 0;
 438
 439	if (pdcs_attr->show)
 440		ret = pdcs_attr->show(entry, buf);
 441
 442	return ret;
 443}
 444
 445/**
 446 * pdcspath_attr_store - Generic write function call wrapper.
 447 * @kobj: The kobject to write info to.
 448 * @attr: The attribute to be modified.
 449 * @buf: The input buffer.
 450 * @count: The size of the buffer.
 451 */
 452static ssize_t
 453pdcspath_attr_store(struct kobject *kobj, struct attribute *attr,
 454			const char *buf, size_t count)
 455{
 456	struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
 457	struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
 458	ssize_t ret = 0;
 459
 460	if (!capable(CAP_SYS_ADMIN))
 461		return -EACCES;
 462
 463	if (pdcs_attr->store)
 464		ret = pdcs_attr->store(entry, buf, count);
 465
 466	return ret;
 467}
 468
 469static const struct sysfs_ops pdcspath_attr_ops = {
 470	.show = pdcspath_attr_show,
 471	.store = pdcspath_attr_store,
 472};
 473
 474/* These are the two attributes of any PDC path. */
 475static PATHS_ATTR(hwpath, 0644, pdcspath_hwpath_read, pdcspath_hwpath_write);
 476static PATHS_ATTR(layer, 0644, pdcspath_layer_read, pdcspath_layer_write);
 477
 478static struct attribute *paths_subsys_attrs[] = {
 479	&paths_attr_hwpath.attr,
 480	&paths_attr_layer.attr,
 481	NULL,
 482};
 483ATTRIBUTE_GROUPS(paths_subsys);
 484
 485/* Specific kobject type for our PDC paths */
 486static struct kobj_type ktype_pdcspath = {
 487	.sysfs_ops = &pdcspath_attr_ops,
 488	.default_groups = paths_subsys_groups,
 489};
 490
 491/* We hard define the 4 types of path we expect to find */
 492static PDCSPATH_ENTRY(PDCS_ADDR_PPRI, primary);
 493static PDCSPATH_ENTRY(PDCS_ADDR_PCON, console);
 494static PDCSPATH_ENTRY(PDCS_ADDR_PALT, alternative);
 495static PDCSPATH_ENTRY(PDCS_ADDR_PKBD, keyboard);
 496
 497/* An array containing all PDC paths we will deal with */
 498static struct pdcspath_entry *pdcspath_entries[] = {
 499	&pdcspath_entry_primary,
 500	&pdcspath_entry_alternative,
 501	&pdcspath_entry_console,
 502	&pdcspath_entry_keyboard,
 503	NULL,
 504};
 505
 506
 507/* For more insight of what's going on here, refer to PDC Procedures doc,
 508 * Section PDC_STABLE */
 509
 510/**
 511 * pdcs_size_read - Stable Storage size output.
 512 * @kobj: The kobject used to share data with userspace.
 513 * @attr: The kobject attributes.
 514 * @buf: The output buffer to write to.
 515 */
 516static ssize_t pdcs_size_read(struct kobject *kobj,
 517			      struct kobj_attribute *attr,
 518			      char *buf)
 519{
 520	char *out = buf;
 521
 522	if (!buf)
 523		return -EINVAL;
 524
 525	/* show the size of the stable storage */
 526	out += sprintf(out, "%ld\n", pdcs_size);
 527
 528	return out - buf;
 529}
 530
 531/**
 532 * pdcs_auto_read - Stable Storage autoboot/search flag output.
 533 * @kobj: The kobject used to share data with userspace.
 534 * @attr: The kobject attributes.
 535 * @buf: The output buffer to write to.
 536 * @knob: The PF_AUTOBOOT or PF_AUTOSEARCH flag
 537 */
 538static ssize_t pdcs_auto_read(struct kobject *kobj,
 539			      struct kobj_attribute *attr,
 540			      char *buf, int knob)
 541{
 542	char *out = buf;
 543	struct pdcspath_entry *pathentry;
 544
 545	if (!buf)
 546		return -EINVAL;
 547
 548	/* Current flags are stored in primary boot path entry */
 549	pathentry = &pdcspath_entry_primary;
 550
 551	read_lock(&pathentry->rw_lock);
 552	out += sprintf(out, "%s\n", (pathentry->devpath.path.flags & knob) ?
 553					"On" : "Off");
 554	read_unlock(&pathentry->rw_lock);
 555
 556	return out - buf;
 557}
 558
 559/**
 560 * pdcs_autoboot_read - Stable Storage autoboot flag output.
 561 * @kobj: The kobject used to share data with userspace.
 562 * @attr: The kobject attributes.
 563 * @buf: The output buffer to write to.
 564 */
 565static ssize_t pdcs_autoboot_read(struct kobject *kobj,
 566				  struct kobj_attribute *attr, char *buf)
 567{
 568	return pdcs_auto_read(kobj, attr, buf, PF_AUTOBOOT);
 569}
 570
 571/**
 572 * pdcs_autosearch_read - Stable Storage autoboot flag output.
 573 * @kobj: The kobject used to share data with userspace.
 574 * @attr: The kobject attributes.
 575 * @buf: The output buffer to write to.
 576 */
 577static ssize_t pdcs_autosearch_read(struct kobject *kobj,
 578				    struct kobj_attribute *attr, char *buf)
 579{
 580	return pdcs_auto_read(kobj, attr, buf, PF_AUTOSEARCH);
 581}
 582
 583/**
 584 * pdcs_timer_read - Stable Storage timer count output (in seconds).
 585 * @kobj: The kobject used to share data with userspace.
 586 * @attr: The kobject attributes.
 587 * @buf: The output buffer to write to.
 588 *
 589 * The value of the timer field correponds to a number of seconds in powers of 2.
 590 */
 591static ssize_t pdcs_timer_read(struct kobject *kobj,
 592			       struct kobj_attribute *attr, char *buf)
 593{
 594	char *out = buf;
 595	struct pdcspath_entry *pathentry;
 596
 597	if (!buf)
 598		return -EINVAL;
 599
 600	/* Current flags are stored in primary boot path entry */
 601	pathentry = &pdcspath_entry_primary;
 602
 603	/* print the timer value in seconds */
 604	read_lock(&pathentry->rw_lock);
 605	out += sprintf(out, "%u\n", (pathentry->devpath.path.flags & PF_TIMER) ?
 606				(1 << (pathentry->devpath.path.flags & PF_TIMER)) : 0);
 607	read_unlock(&pathentry->rw_lock);
 608
 609	return out - buf;
 610}
 611
 612/**
 613 * pdcs_osid_read - Stable Storage OS ID register output.
 614 * @kobj: The kobject used to share data with userspace.
 615 * @attr: The kobject attributes.
 616 * @buf: The output buffer to write to.
 617 */
 618static ssize_t pdcs_osid_read(struct kobject *kobj,
 619			      struct kobj_attribute *attr, char *buf)
 620{
 621	char *out = buf;
 622
 623	if (!buf)
 624		return -EINVAL;
 625
 626	out += sprintf(out, "%s dependent data (0x%.4x)\n",
 627		os_id_to_string(pdcs_osid), pdcs_osid);
 628
 629	return out - buf;
 630}
 631
 632/**
 633 * pdcs_osdep1_read - Stable Storage OS-Dependent data area 1 output.
 634 * @kobj: The kobject used to share data with userspace.
 635 * @attr: The kobject attributes.
 636 * @buf: The output buffer to write to.
 637 *
 638 * This can hold 16 bytes of OS-Dependent data.
 639 */
 640static ssize_t pdcs_osdep1_read(struct kobject *kobj,
 641				struct kobj_attribute *attr, char *buf)
 642{
 643	char *out = buf;
 644	u32 result[4];
 645
 646	if (!buf)
 647		return -EINVAL;
 648
 649	if (pdc_stable_read(PDCS_ADDR_OSD1, &result, sizeof(result)) != PDC_OK)
 650		return -EIO;
 651
 652	out += sprintf(out, "0x%.8x\n", result[0]);
 653	out += sprintf(out, "0x%.8x\n", result[1]);
 654	out += sprintf(out, "0x%.8x\n", result[2]);
 655	out += sprintf(out, "0x%.8x\n", result[3]);
 656
 657	return out - buf;
 658}
 659
 660/**
 661 * pdcs_diagnostic_read - Stable Storage Diagnostic register output.
 662 * @kobj: The kobject used to share data with userspace.
 663 * @attr: The kobject attributes.
 664 * @buf: The output buffer to write to.
 665 *
 666 * I have NFC how to interpret the content of that register ;-).
 667 */
 668static ssize_t pdcs_diagnostic_read(struct kobject *kobj,
 669				    struct kobj_attribute *attr, char *buf)
 670{
 671	char *out = buf;
 672	u32 result;
 673
 674	if (!buf)
 675		return -EINVAL;
 676
 677	/* get diagnostic */
 678	if (pdc_stable_read(PDCS_ADDR_DIAG, &result, sizeof(result)) != PDC_OK)
 679		return -EIO;
 680
 681	out += sprintf(out, "0x%.4x\n", (result >> 16));
 682
 683	return out - buf;
 684}
 685
 686/**
 687 * pdcs_fastsize_read - Stable Storage FastSize register output.
 688 * @kobj: The kobject used to share data with userspace.
 689 * @attr: The kobject attributes.
 690 * @buf: The output buffer to write to.
 691 *
 692 * This register holds the amount of system RAM to be tested during boot sequence.
 693 */
 694static ssize_t pdcs_fastsize_read(struct kobject *kobj,
 695				  struct kobj_attribute *attr, char *buf)
 696{
 697	char *out = buf;
 698	u32 result;
 699
 700	if (!buf)
 701		return -EINVAL;
 702
 703	/* get fast-size */
 704	if (pdc_stable_read(PDCS_ADDR_FSIZ, &result, sizeof(result)) != PDC_OK)
 705		return -EIO;
 706
 707	if ((result & 0x0F) < 0x0E)
 708		out += sprintf(out, "%d kB", (1<<(result & 0x0F))*256);
 709	else
 710		out += sprintf(out, "All");
 711	out += sprintf(out, "\n");
 712	
 713	return out - buf;
 714}
 715
 716/**
 717 * pdcs_osdep2_read - Stable Storage OS-Dependent data area 2 output.
 718 * @kobj: The kobject used to share data with userspace.
 719 * @attr: The kobject attributes.
 720 * @buf: The output buffer to write to.
 721 *
 722 * This can hold pdcs_size - 224 bytes of OS-Dependent data, when available.
 723 */
 724static ssize_t pdcs_osdep2_read(struct kobject *kobj,
 725				struct kobj_attribute *attr, char *buf)
 726{
 727	char *out = buf;
 728	unsigned long size;
 729	unsigned short i;
 730	u32 result;
 731
 732	if (unlikely(pdcs_size <= 224))
 733		return -ENODATA;
 734
 735	size = pdcs_size - 224;
 736
 737	if (!buf)
 738		return -EINVAL;
 739
 740	for (i=0; i<size; i+=4) {
 741		if (unlikely(pdc_stable_read(PDCS_ADDR_OSD2 + i, &result,
 742					sizeof(result)) != PDC_OK))
 743			return -EIO;
 744		out += sprintf(out, "0x%.8x\n", result);
 745	}
 746
 747	return out - buf;
 748}
 749
 750/**
 751 * pdcs_auto_write - This function handles autoboot/search flag modifying.
 752 * @kobj: The kobject used to share data with userspace.
 753 * @attr: The kobject attributes.
 754 * @buf: The input buffer to read from.
 755 * @count: The number of bytes to be read.
 756 * @knob: The PF_AUTOBOOT or PF_AUTOSEARCH flag
 757 * 
 758 * We will call this function to change the current autoboot flag.
 759 * We expect a precise syntax:
 760 *	\"n\" (n == 0 or 1) to toggle AutoBoot Off or On
 761 */
 762static ssize_t pdcs_auto_write(struct kobject *kobj,
 763			       struct kobj_attribute *attr, const char *buf,
 764			       size_t count, int knob)
 765{
 766	struct pdcspath_entry *pathentry;
 767	unsigned char flags;
 768	char in[8], *temp;
 769	char c;
 770
 771	if (!capable(CAP_SYS_ADMIN))
 772		return -EACCES;
 773
 774	if (!buf || !count)
 775		return -EINVAL;
 776
 777	/* We'll use a local copy of buf */
 778	count = min_t(size_t, count, sizeof(in)-1);
 779	strscpy(in, buf, count + 1);
 
 780
 781	/* Current flags are stored in primary boot path entry */
 782	pathentry = &pdcspath_entry_primary;
 783	
 784	/* Be nice to the existing flag record */
 785	read_lock(&pathentry->rw_lock);
 786	flags = pathentry->devpath.path.flags;
 787	read_unlock(&pathentry->rw_lock);
 788	
 789	DPRINTK("%s: flags before: 0x%X\n", __func__, flags);
 790
 791	temp = skip_spaces(in);
 792
 793	c = *temp++ - '0';
 794	if ((c != 0) && (c != 1))
 795		goto parse_error;
 796	if (c == 0)
 797		flags &= ~knob;
 798	else
 799		flags |= knob;
 800	
 801	DPRINTK("%s: flags after: 0x%X\n", __func__, flags);
 802		
 803	/* So far so good, let's get in deep */
 804	write_lock(&pathentry->rw_lock);
 805	
 806	/* Change the path entry flags first */
 807	pathentry->devpath.path.flags = flags;
 808		
 809	/* Now, dive in. Write back to the hardware */
 810	pdcspath_store(pathentry);
 811	write_unlock(&pathentry->rw_lock);
 812	
 813	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" to \"%s\"\n",
 814		(knob & PF_AUTOBOOT) ? "autoboot" : "autosearch",
 815		(flags & knob) ? "On" : "Off");
 816	
 817	return count;
 818
 819parse_error:
 820	printk(KERN_WARNING "%s: Parse error: expect \"n\" (n == 0 or 1)\n", __func__);
 821	return -EINVAL;
 822}
 823
 824/**
 825 * pdcs_autoboot_write - This function handles autoboot flag modifying.
 826 * @kobj: The kobject used to share data with userspace.
 827 * @attr: The kobject attributes.
 828 * @buf: The input buffer to read from.
 829 * @count: The number of bytes to be read.
 830 *
 831 * We will call this function to change the current boot flags.
 832 * We expect a precise syntax:
 833 *	\"n\" (n == 0 or 1) to toggle AutoSearch Off or On
 834 */
 835static ssize_t pdcs_autoboot_write(struct kobject *kobj,
 836				   struct kobj_attribute *attr,
 837				   const char *buf, size_t count)
 838{
 839	return pdcs_auto_write(kobj, attr, buf, count, PF_AUTOBOOT);
 840}
 841
 842/**
 843 * pdcs_autosearch_write - This function handles autosearch flag modifying.
 844 * @kobj: The kobject used to share data with userspace.
 845 * @attr: The kobject attributes.
 846 * @buf: The input buffer to read from.
 847 * @count: The number of bytes to be read.
 848 *
 849 * We will call this function to change the current boot flags.
 850 * We expect a precise syntax:
 851 *	\"n\" (n == 0 or 1) to toggle AutoSearch Off or On
 852 */
 853static ssize_t pdcs_autosearch_write(struct kobject *kobj,
 854				     struct kobj_attribute *attr,
 855				     const char *buf, size_t count)
 856{
 857	return pdcs_auto_write(kobj, attr, buf, count, PF_AUTOSEARCH);
 858}
 859
 860/**
 861 * pdcs_osdep1_write - Stable Storage OS-Dependent data area 1 input.
 862 * @kobj: The kobject used to share data with userspace.
 863 * @attr: The kobject attributes.
 864 * @buf: The input buffer to read from.
 865 * @count: The number of bytes to be read.
 866 *
 867 * This can store 16 bytes of OS-Dependent data. We use a byte-by-byte
 868 * write approach. It's up to userspace to deal with it when constructing
 869 * its input buffer.
 870 */
 871static ssize_t pdcs_osdep1_write(struct kobject *kobj,
 872				 struct kobj_attribute *attr,
 873				 const char *buf, size_t count)
 874{
 875	u8 in[16];
 876
 877	if (!capable(CAP_SYS_ADMIN))
 878		return -EACCES;
 879
 880	if (!buf || !count)
 881		return -EINVAL;
 882
 883	if (unlikely(pdcs_osid != OS_ID_LINUX))
 884		return -EPERM;
 885
 886	if (count > 16)
 887		return -EMSGSIZE;
 888
 889	/* We'll use a local copy of buf */
 890	memset(in, 0, 16);
 891	memcpy(in, buf, count);
 892
 893	if (pdc_stable_write(PDCS_ADDR_OSD1, &in, sizeof(in)) != PDC_OK)
 894		return -EIO;
 895
 896	return count;
 897}
 898
 899/**
 900 * pdcs_osdep2_write - Stable Storage OS-Dependent data area 2 input.
 901 * @kobj: The kobject used to share data with userspace.
 902 * @attr: The kobject attributes.
 903 * @buf: The input buffer to read from.
 904 * @count: The number of bytes to be read.
 905 *
 906 * This can store pdcs_size - 224 bytes of OS-Dependent data. We use a
 907 * byte-by-byte write approach. It's up to userspace to deal with it when
 908 * constructing its input buffer.
 909 */
 910static ssize_t pdcs_osdep2_write(struct kobject *kobj,
 911				 struct kobj_attribute *attr,
 912				 const char *buf, size_t count)
 913{
 914	unsigned long size;
 915	unsigned short i;
 916	u8 in[4];
 917
 918	if (!capable(CAP_SYS_ADMIN))
 919		return -EACCES;
 920
 921	if (!buf || !count)
 922		return -EINVAL;
 923
 924	if (unlikely(pdcs_size <= 224))
 925		return -ENOSYS;
 926
 927	if (unlikely(pdcs_osid != OS_ID_LINUX))
 928		return -EPERM;
 929
 930	size = pdcs_size - 224;
 931
 932	if (count > size)
 933		return -EMSGSIZE;
 934
 935	/* We'll use a local copy of buf */
 936
 937	for (i=0; i<count; i+=4) {
 938		memset(in, 0, 4);
 939		memcpy(in, buf+i, (count-i < 4) ? count-i : 4);
 940		if (unlikely(pdc_stable_write(PDCS_ADDR_OSD2 + i, &in,
 941					sizeof(in)) != PDC_OK))
 942			return -EIO;
 943	}
 944
 945	return count;
 946}
 947
 948/* The remaining attributes. */
 949static PDCS_ATTR(size, 0444, pdcs_size_read, NULL);
 950static PDCS_ATTR(autoboot, 0644, pdcs_autoboot_read, pdcs_autoboot_write);
 951static PDCS_ATTR(autosearch, 0644, pdcs_autosearch_read, pdcs_autosearch_write);
 952static PDCS_ATTR(timer, 0444, pdcs_timer_read, NULL);
 953static PDCS_ATTR(osid, 0444, pdcs_osid_read, NULL);
 954static PDCS_ATTR(osdep1, 0600, pdcs_osdep1_read, pdcs_osdep1_write);
 955static PDCS_ATTR(diagnostic, 0400, pdcs_diagnostic_read, NULL);
 956static PDCS_ATTR(fastsize, 0400, pdcs_fastsize_read, NULL);
 957static PDCS_ATTR(osdep2, 0600, pdcs_osdep2_read, pdcs_osdep2_write);
 958
 959static struct attribute *pdcs_subsys_attrs[] = {
 960	&pdcs_attr_size.attr,
 961	&pdcs_attr_autoboot.attr,
 962	&pdcs_attr_autosearch.attr,
 963	&pdcs_attr_timer.attr,
 964	&pdcs_attr_osid.attr,
 965	&pdcs_attr_osdep1.attr,
 966	&pdcs_attr_diagnostic.attr,
 967	&pdcs_attr_fastsize.attr,
 968	&pdcs_attr_osdep2.attr,
 969	NULL,
 970};
 971
 972static const struct attribute_group pdcs_attr_group = {
 973	.attrs = pdcs_subsys_attrs,
 974};
 975
 976static struct kobject *stable_kobj;
 977static struct kset *paths_kset;
 978
 979/**
 980 * pdcs_register_pathentries - Prepares path entries kobjects for sysfs usage.
 981 * 
 982 * It creates kobjects corresponding to each path entry with nice sysfs
 983 * links to the real device. This is where the magic takes place: when
 984 * registering the subsystem attributes during module init, each kobject hereby
 985 * created will show in the sysfs tree as a folder containing files as defined
 986 * by path_subsys_attr[].
 987 */
 988static inline int __init
 989pdcs_register_pathentries(void)
 990{
 991	unsigned short i;
 992	struct pdcspath_entry *entry;
 993	int err;
 994	
 995	/* Initialize the entries rw_lock before anything else */
 996	for (i = 0; (entry = pdcspath_entries[i]); i++)
 997		rwlock_init(&entry->rw_lock);
 998
 999	for (i = 0; (entry = pdcspath_entries[i]); i++) {
1000		write_lock(&entry->rw_lock);
1001		err = pdcspath_fetch(entry);
1002		write_unlock(&entry->rw_lock);
1003
1004		if (err < 0)
1005			continue;
1006
1007		entry->kobj.kset = paths_kset;
1008		err = kobject_init_and_add(&entry->kobj, &ktype_pdcspath, NULL,
1009					   "%s", entry->name);
1010		if (err) {
1011			kobject_put(&entry->kobj);
1012			return err;
1013		}
1014
1015		/* kobject is now registered */
1016		write_lock(&entry->rw_lock);
1017		entry->ready = 2;
1018		write_unlock(&entry->rw_lock);
1019		
1020		/* Add a nice symlink to the real device */
1021		if (entry->dev) {
1022			err = sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
1023			WARN_ON(err);
1024		}
1025
1026		kobject_uevent(&entry->kobj, KOBJ_ADD);
1027	}
1028	
1029	return 0;
1030}
1031
1032/**
1033 * pdcs_unregister_pathentries - Routine called when unregistering the module.
1034 */
1035static inline void
1036pdcs_unregister_pathentries(void)
1037{
1038	unsigned short i;
1039	struct pdcspath_entry *entry;
1040	
1041	for (i = 0; (entry = pdcspath_entries[i]); i++) {
1042		read_lock(&entry->rw_lock);
1043		if (entry->ready >= 2)
1044			kobject_put(&entry->kobj);
1045		read_unlock(&entry->rw_lock);
1046	}
1047}
1048
1049/*
1050 * For now we register the stable subsystem with the firmware subsystem
1051 * and the paths subsystem with the stable subsystem
1052 */
1053static int __init
1054pdc_stable_init(void)
1055{
1056	int rc = 0, error;
1057	u32 result;
1058
1059	/* find the size of the stable storage */
1060	if (pdc_stable_get_size(&pdcs_size) != PDC_OK) 
1061		return -ENODEV;
1062
1063	/* make sure we have enough data */
1064	if (pdcs_size < 96)
1065		return -ENODATA;
1066
1067	printk(KERN_INFO PDCS_PREFIX " facility v%s\n", PDCS_VERSION);
1068
1069	/* get OSID */
1070	if (pdc_stable_read(PDCS_ADDR_OSID, &result, sizeof(result)) != PDC_OK)
1071		return -EIO;
1072
1073	/* the actual result is 16 bits away */
1074	pdcs_osid = (u16)(result >> 16);
1075
1076	/* For now we'll register the directory at /sys/firmware/stable */
1077	stable_kobj = kobject_create_and_add("stable", firmware_kobj);
1078	if (!stable_kobj) {
1079		rc = -ENOMEM;
1080		goto fail_firmreg;
1081	}
1082
1083	/* Don't forget the root entries */
1084	error = sysfs_create_group(stable_kobj, &pdcs_attr_group);
1085	if (error) {
1086		rc = -ENOMEM;
1087		goto fail_ksetreg;
1088	}
1089
1090	/* register the paths kset as a child of the stable kset */
1091	paths_kset = kset_create_and_add("paths", NULL, stable_kobj);
1092	if (!paths_kset) {
1093		rc = -ENOMEM;
1094		goto fail_ksetreg;
1095	}
1096
1097	/* now we create all "files" for the paths kset */
1098	if ((rc = pdcs_register_pathentries()))
1099		goto fail_pdcsreg;
1100
1101	return rc;
1102	
1103fail_pdcsreg:
1104	pdcs_unregister_pathentries();
1105	kset_unregister(paths_kset);
1106	
1107fail_ksetreg:
1108	kobject_put(stable_kobj);
1109	
1110fail_firmreg:
1111	printk(KERN_INFO PDCS_PREFIX " bailing out\n");
1112	return rc;
1113}
1114
1115static void __exit
1116pdc_stable_exit(void)
1117{
1118	pdcs_unregister_pathentries();
1119	kset_unregister(paths_kset);
1120	kobject_put(stable_kobj);
1121}
1122
1123
1124module_init(pdc_stable_init);
1125module_exit(pdc_stable_exit);