1/* 
   2 *    Interfaces to retrieve and set PDC Stable options (firmware)
   3 *
   4 *    Copyright (C) 2005-2006 Thibaut VARENE <varenet@parisc-linux.org>
   5 *
   6 *    This program is free software; you can redistribute it and/or modify
   7 *    it under the terms of the GNU General Public License, version 2, as
   8 *    published by the Free Software Foundation.
   9 *
  10 *    This program is distributed in the hope that it will be useful,
  11 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 *    GNU General Public License for more details.
  14 *
  15 *    You should have received a copy of the GNU General Public License
  16 *    along with this program; if not, write to the Free Software
  17 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 *
  19 *
  20 *    DEV NOTE: the PDC Procedures reference states that:
  21 *    "A minimum of 96 bytes of Stable Storage is required. Providing more than
  22 *    96 bytes of Stable Storage is optional [...]. Failure to provide the
  23 *    optional locations from 96 to 192 results in the loss of certain
  24 *    functionality during boot."
  25 *
  26 *    Since locations between 96 and 192 are the various paths, most (if not
  27 *    all) PA-RISC machines should have them. Anyway, for safety reasons, the
  28 *    following code can deal with just 96 bytes of Stable Storage, and all
  29 *    sizes between 96 and 192 bytes (provided they are multiple of struct
  30 *    device_path size, eg: 128, 160 and 192) to provide full information.
  31 *    One last word: there's one path we can always count on: the primary path.
  32 *    Anything above 224 bytes is used for 'osdep2' OS-dependent storage area.
  33 *
  34 *    The first OS-dependent area should always be available. Obviously, this is
  35 *    not true for the other one. Also bear in mind that reading/writing from/to
  36 *    osdep2 is much more expensive than from/to osdep1.
  37 *    NOTE: We do not handle the 2 bytes OS-dep area at 0x5D, nor the first
  38 *    2 bytes of storage available right after OSID. That's a total of 4 bytes
  39 *    sacrificed: -ETOOLAZY :P
  40 *
  41 *    The current policy wrt file permissions is:
  42 *	- write: root only
  43 *	- read: (reading triggers PDC calls) ? root only : everyone
  44 *    The rationale is that PDC calls could hog (DoS) the machine.
  45 *
  46 *	TODO:
  47 *	- timer/fastsize write calls
  48 */
  49
  50#undef PDCS_DEBUG
  51#ifdef PDCS_DEBUG
  52#define DPRINTK(fmt, args...)	printk(KERN_DEBUG fmt, ## args)
  53#else
  54#define DPRINTK(fmt, args...)
  55#endif
  56
  57#include <linux/module.h>
  58#include <linux/init.h>
  59#include <linux/kernel.h>
  60#include <linux/string.h>
  61#include <linux/capability.h>
  62#include <linux/ctype.h>
  63#include <linux/sysfs.h>
  64#include <linux/kobject.h>
  65#include <linux/device.h>
  66#include <linux/errno.h>
  67#include <linux/spinlock.h>
  68
  69#include <asm/pdc.h>
  70#include <asm/page.h>
  71#include <asm/uaccess.h>
  72#include <asm/hardware.h>
  73
  74#define PDCS_VERSION	"0.30"
  75#define PDCS_PREFIX	"PDC Stable Storage"
  76
  77#define PDCS_ADDR_PPRI	0x00
  78#define PDCS_ADDR_OSID	0x40
  79#define PDCS_ADDR_OSD1	0x48
  80#define PDCS_ADDR_DIAG	0x58
  81#define PDCS_ADDR_FSIZ	0x5C
  82#define PDCS_ADDR_PCON	0x60
  83#define PDCS_ADDR_PALT	0x80
  84#define PDCS_ADDR_PKBD	0xA0
  85#define PDCS_ADDR_OSD2	0xE0
  86
  87MODULE_AUTHOR("Thibaut VARENE <varenet@parisc-linux.org>");
  88MODULE_DESCRIPTION("sysfs interface to HP PDC Stable Storage data");
  89MODULE_LICENSE("GPL");
  90MODULE_VERSION(PDCS_VERSION);
  91
  92/* holds Stable Storage size. Initialized once and for all, no lock needed */
  93static unsigned long pdcs_size __read_mostly;
  94
  95/* holds OS ID. Initialized once and for all, hopefully to 0x0006 */
  96static u16 pdcs_osid __read_mostly;
  97
  98/* This struct defines what we need to deal with a parisc pdc path entry */
  99struct pdcspath_entry {
 100	rwlock_t rw_lock;		/* to protect path entry access */
 101	short ready;			/* entry record is valid if != 0 */
 102	unsigned long addr;		/* entry address in stable storage */
 103	char *name;			/* entry name */
 104	struct device_path devpath;	/* device path in parisc representation */
 105	struct device *dev;		/* corresponding device */
 106	struct kobject kobj;
 107};
 108
 109struct pdcspath_attribute {
 110	struct attribute attr;
 111	ssize_t (*show)(struct pdcspath_entry *entry, char *buf);
 112	ssize_t (*store)(struct pdcspath_entry *entry, const char *buf, size_t count);
 113};
 114
 115#define PDCSPATH_ENTRY(_addr, _name) \
 116struct pdcspath_entry pdcspath_entry_##_name = { \
 117	.ready = 0, \
 118	.addr = _addr, \
 119	.name = __stringify(_name), \
 120};
 121
 122#define PDCS_ATTR(_name, _mode, _show, _store) \
 123struct kobj_attribute pdcs_attr_##_name = { \
 124	.attr = {.name = __stringify(_name), .mode = _mode}, \
 125	.show = _show, \
 126	.store = _store, \
 127};
 128
 129#define PATHS_ATTR(_name, _mode, _show, _store) \
 130struct pdcspath_attribute paths_attr_##_name = { \
 131	.attr = {.name = __stringify(_name), .mode = _mode}, \
 132	.show = _show, \
 133	.store = _store, \
 134};
 135
 136#define to_pdcspath_attribute(_attr) container_of(_attr, struct pdcspath_attribute, attr)
 137#define to_pdcspath_entry(obj)  container_of(obj, struct pdcspath_entry, kobj)
 138
 139/**
 140 * pdcspath_fetch - This function populates the path entry structs.
 141 * @entry: A pointer to an allocated pdcspath_entry.
 142 * 
 143 * The general idea is that you don't read from the Stable Storage every time
 144 * you access the files provided by the facilities. We store a copy of the
 145 * content of the stable storage WRT various paths in these structs. We read
 146 * these structs when reading the files, and we will write to these structs when
 147 * writing to the files, and only then write them back to the Stable Storage.
 148 *
 149 * This function expects to be called with @entry->rw_lock write-hold.
 150 */
 151static int
 152pdcspath_fetch(struct pdcspath_entry *entry)
 153{
 154	struct device_path *devpath;
 155
 156	if (!entry)
 157		return -EINVAL;
 158
 159	devpath = &entry->devpath;
 160	
 161	DPRINTK("%s: fetch: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
 162			entry, devpath, entry->addr);
 163
 164	/* addr, devpath and count must be word aligned */
 165	if (pdc_stable_read(entry->addr, devpath, sizeof(*devpath)) != PDC_OK)
 166		return -EIO;
 167		
 168	/* Find the matching device.
 169	   NOTE: hardware_path overlays with device_path, so the nice cast can
 170	   be used */
 171	entry->dev = hwpath_to_device((struct hardware_path *)devpath);
 172
 173	entry->ready = 1;
 174	
 175	DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
 176	
 177	return 0;
 178}
 179
 180/**
 181 * pdcspath_store - This function writes a path to stable storage.
 182 * @entry: A pointer to an allocated pdcspath_entry.
 183 * 
 184 * It can be used in two ways: either by passing it a preset devpath struct
 185 * containing an already computed hardware path, or by passing it a device
 186 * pointer, from which it'll find out the corresponding hardware path.
 187 * For now we do not handle the case where there's an error in writing to the
 188 * Stable Storage area, so you'd better not mess up the data :P
 189 *
 190 * This function expects to be called with @entry->rw_lock write-hold.
 191 */
 192static void
 193pdcspath_store(struct pdcspath_entry *entry)
 194{
 195	struct device_path *devpath;
 196
 197	BUG_ON(!entry);
 198
 199	devpath = &entry->devpath;
 200	
 201	/* We expect the caller to set the ready flag to 0 if the hardware
 202	   path struct provided is invalid, so that we know we have to fill it.
 203	   First case, we don't have a preset hwpath... */
 204	if (!entry->ready) {
 205		/* ...but we have a device, map it */
 206		BUG_ON(!entry->dev);
 207		device_to_hwpath(entry->dev, (struct hardware_path *)devpath);
 208	}
 209	/* else, we expect the provided hwpath to be valid. */
 210	
 211	DPRINTK("%s: store: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
 212			entry, devpath, entry->addr);
 213
 214	/* addr, devpath and count must be word aligned */
 215	if (pdc_stable_write(entry->addr, devpath, sizeof(*devpath)) != PDC_OK) {
 216		printk(KERN_ERR "%s: an error occurred when writing to PDC.\n"
 217				"It is likely that the Stable Storage data has been corrupted.\n"
 218				"Please check it carefully upon next reboot.\n", __func__);
 219		WARN_ON(1);
 220	}
 221		
 222	/* kobject is already registered */
 223	entry->ready = 2;
 224	
 225	DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
 226}
 227
 228/**
 229 * pdcspath_hwpath_read - This function handles hardware path pretty printing.
 230 * @entry: An allocated and populated pdscpath_entry struct.
 231 * @buf: The output buffer to write to.
 232 * 
 233 * We will call this function to format the output of the hwpath attribute file.
 234 */
 235static ssize_t
 236pdcspath_hwpath_read(struct pdcspath_entry *entry, char *buf)
 237{
 238	char *out = buf;
 239	struct device_path *devpath;
 240	short i;
 241
 242	if (!entry || !buf)
 243		return -EINVAL;
 244
 245	read_lock(&entry->rw_lock);
 246	devpath = &entry->devpath;
 247	i = entry->ready;
 248	read_unlock(&entry->rw_lock);
 249
 250	if (!i)	/* entry is not ready */
 251		return -ENODATA;
 252	
 253	for (i = 0; i < 6; i++) {
 254		if (devpath->bc[i] >= 128)
 255			continue;
 256		out += sprintf(out, "%u/", (unsigned char)devpath->bc[i]);
 257	}
 258	out += sprintf(out, "%u\n", (unsigned char)devpath->mod);
 259	
 260	return out - buf;
 261}
 262
 263/**
 264 * pdcspath_hwpath_write - This function handles hardware path modifying.
 265 * @entry: An allocated and populated pdscpath_entry struct.
 266 * @buf: The input buffer to read from.
 267 * @count: The number of bytes to be read.
 268 * 
 269 * We will call this function to change the current hardware path.
 270 * Hardware paths are to be given '/'-delimited, without brackets.
 271 * We make sure that the provided path actually maps to an existing
 272 * device, BUT nothing would prevent some foolish user to set the path to some
 273 * PCI bridge or even a CPU...
 274 * A better work around would be to make sure we are at the end of a device tree
 275 * for instance, but it would be IMHO beyond the simple scope of that driver.
 276 * The aim is to provide a facility. Data correctness is left to userland.
 277 */
 278static ssize_t
 279pdcspath_hwpath_write(struct pdcspath_entry *entry, const char *buf, size_t count)
 280{
 281	struct hardware_path hwpath;
 282	unsigned short i;
 283	char in[count+1], *temp;
 284	struct device *dev;
 285	int ret;
 286
 287	if (!entry || !buf || !count)
 288		return -EINVAL;
 289
 290	/* We'll use a local copy of buf */
 291	memset(in, 0, count+1);
 292	strncpy(in, buf, count);
 293	
 294	/* Let's clean up the target. 0xff is a blank pattern */
 295	memset(&hwpath, 0xff, sizeof(hwpath));
 296	
 297	/* First, pick the mod field (the last one of the input string) */
 298	if (!(temp = strrchr(in, '/')))
 299		return -EINVAL;
 300			
 301	hwpath.mod = simple_strtoul(temp+1, NULL, 10);
 302	in[temp-in] = '\0';	/* truncate the remaining string. just precaution */
 303	DPRINTK("%s: mod: %d\n", __func__, hwpath.mod);
 304	
 305	/* Then, loop for each delimiter, making sure we don't have too many.
 306	   we write the bc fields in a down-top way. No matter what, we stop
 307	   before writing the last field. If there are too many fields anyway,
 308	   then the user is a moron and it'll be caught up later when we'll
 309	   check the consistency of the given hwpath. */
 310	for (i=5; ((temp = strrchr(in, '/'))) && (temp-in > 0) && (likely(i)); i--) {
 311		hwpath.bc[i] = simple_strtoul(temp+1, NULL, 10);
 312		in[temp-in] = '\0';
 313		DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.bc[i]);
 314	}
 315	
 316	/* Store the final field */		
 317	hwpath.bc[i] = simple_strtoul(in, NULL, 10);
 318	DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.bc[i]);
 319	
 320	/* Now we check that the user isn't trying to lure us */
 321	if (!(dev = hwpath_to_device((struct hardware_path *)&hwpath))) {
 322		printk(KERN_WARNING "%s: attempt to set invalid \"%s\" "
 323			"hardware path: %s\n", __func__, entry->name, buf);
 324		return -EINVAL;
 325	}
 326	
 327	/* So far so good, let's get in deep */
 328	write_lock(&entry->rw_lock);
 329	entry->ready = 0;
 330	entry->dev = dev;
 331	
 332	/* Now, dive in. Write back to the hardware */
 333	pdcspath_store(entry);
 334	
 335	/* Update the symlink to the real device */
 336	sysfs_remove_link(&entry->kobj, "device");
 337	ret = sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
 338	WARN_ON(ret);
 339
 340	write_unlock(&entry->rw_lock);
 341	
 342	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" path to \"%s\"\n",
 343		entry->name, buf);
 344	
 345	return count;
 346}
 347
 348/**
 349 * pdcspath_layer_read - Extended layer (eg. SCSI ids) pretty printing.
 350 * @entry: An allocated and populated pdscpath_entry struct.
 351 * @buf: The output buffer to write to.
 352 * 
 353 * We will call this function to format the output of the layer attribute file.
 354 */
 355static ssize_t
 356pdcspath_layer_read(struct pdcspath_entry *entry, char *buf)
 357{
 358	char *out = buf;
 359	struct device_path *devpath;
 360	short i;
 361
 362	if (!entry || !buf)
 363		return -EINVAL;
 364	
 365	read_lock(&entry->rw_lock);
 366	devpath = &entry->devpath;
 367	i = entry->ready;
 368	read_unlock(&entry->rw_lock);
 369
 370	if (!i)	/* entry is not ready */
 371		return -ENODATA;
 372	
 373	for (i = 0; i < 6 && devpath->layers[i]; i++)
 374		out += sprintf(out, "%u ", devpath->layers[i]);
 375
 376	out += sprintf(out, "\n");
 377	
 378	return out - buf;
 379}
 380
 381/**
 382 * pdcspath_layer_write - This function handles extended layer modifying.
 383 * @entry: An allocated and populated pdscpath_entry struct.
 384 * @buf: The input buffer to read from.
 385 * @count: The number of bytes to be read.
 386 * 
 387 * We will call this function to change the current layer value.
 388 * Layers are to be given '.'-delimited, without brackets.
 389 * XXX beware we are far less checky WRT input data provided than for hwpath.
 390 * Potential harm can be done, since there's no way to check the validity of
 391 * the layer fields.
 392 */
 393static ssize_t
 394pdcspath_layer_write(struct pdcspath_entry *entry, const char *buf, size_t count)
 395{
 396	unsigned int layers[6]; /* device-specific info (ctlr#, unit#, ...) */
 397	unsigned short i;
 398	char in[count+1], *temp;
 399
 400	if (!entry || !buf || !count)
 401		return -EINVAL;
 402
 403	/* We'll use a local copy of buf */
 404	memset(in, 0, count+1);
 405	strncpy(in, buf, count);
 406	
 407	/* Let's clean up the target. 0 is a blank pattern */
 408	memset(&layers, 0, sizeof(layers));
 409	
 410	/* First, pick the first layer */
 411	if (unlikely(!isdigit(*in)))
 412		return -EINVAL;
 413	layers[0] = simple_strtoul(in, NULL, 10);
 414	DPRINTK("%s: layer[0]: %d\n", __func__, layers[0]);
 415	
 416	temp = in;
 417	for (i=1; ((temp = strchr(temp, '.'))) && (likely(i<6)); i++) {
 418		if (unlikely(!isdigit(*(++temp))))
 419			return -EINVAL;
 420		layers[i] = simple_strtoul(temp, NULL, 10);
 421		DPRINTK("%s: layer[%d]: %d\n", __func__, i, layers[i]);
 422	}
 423		
 424	/* So far so good, let's get in deep */
 425	write_lock(&entry->rw_lock);
 426	
 427	/* First, overwrite the current layers with the new ones, not touching
 428	   the hardware path. */
 429	memcpy(&entry->devpath.layers, &layers, sizeof(layers));
 430	
 431	/* Now, dive in. Write back to the hardware */
 432	pdcspath_store(entry);
 433	write_unlock(&entry->rw_lock);
 434	
 435	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" layers to \"%s\"\n",
 436		entry->name, buf);
 437	
 438	return count;
 439}
 440
 441/**
 442 * pdcspath_attr_show - Generic read function call wrapper.
 443 * @kobj: The kobject to get info from.
 444 * @attr: The attribute looked upon.
 445 * @buf: The output buffer.
 446 */
 447static ssize_t
 448pdcspath_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
 449{
 450	struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
 451	struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
 452	ssize_t ret = 0;
 453
 454	if (pdcs_attr->show)
 455		ret = pdcs_attr->show(entry, buf);
 456
 457	return ret;
 458}
 459
 460/**
 461 * pdcspath_attr_store - Generic write function call wrapper.
 462 * @kobj: The kobject to write info to.
 463 * @attr: The attribute to be modified.
 464 * @buf: The input buffer.
 465 * @count: The size of the buffer.
 466 */
 467static ssize_t
 468pdcspath_attr_store(struct kobject *kobj, struct attribute *attr,
 469			const char *buf, size_t count)
 470{
 471	struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
 472	struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
 473	ssize_t ret = 0;
 474
 475	if (!capable(CAP_SYS_ADMIN))
 476		return -EACCES;
 477
 478	if (pdcs_attr->store)
 479		ret = pdcs_attr->store(entry, buf, count);
 480
 481	return ret;
 482}
 483
 484static const struct sysfs_ops pdcspath_attr_ops = {
 485	.show = pdcspath_attr_show,
 486	.store = pdcspath_attr_store,
 487};
 488
 489/* These are the two attributes of any PDC path. */
 490static PATHS_ATTR(hwpath, 0644, pdcspath_hwpath_read, pdcspath_hwpath_write);
 491static PATHS_ATTR(layer, 0644, pdcspath_layer_read, pdcspath_layer_write);
 492
 493static struct attribute *paths_subsys_attrs[] = {
 494	&paths_attr_hwpath.attr,
 495	&paths_attr_layer.attr,
 496	NULL,
 497};
 498
 499/* Specific kobject type for our PDC paths */
 500static struct kobj_type ktype_pdcspath = {
 501	.sysfs_ops = &pdcspath_attr_ops,
 502	.default_attrs = paths_subsys_attrs,
 503};
 504
 505/* We hard define the 4 types of path we expect to find */
 506static PDCSPATH_ENTRY(PDCS_ADDR_PPRI, primary);
 507static PDCSPATH_ENTRY(PDCS_ADDR_PCON, console);
 508static PDCSPATH_ENTRY(PDCS_ADDR_PALT, alternative);
 509static PDCSPATH_ENTRY(PDCS_ADDR_PKBD, keyboard);
 510
 511/* An array containing all PDC paths we will deal with */
 512static struct pdcspath_entry *pdcspath_entries[] = {
 513	&pdcspath_entry_primary,
 514	&pdcspath_entry_alternative,
 515	&pdcspath_entry_console,
 516	&pdcspath_entry_keyboard,
 517	NULL,
 518};
 519
 520
 521/* For more insight of what's going on here, refer to PDC Procedures doc,
 522 * Section PDC_STABLE */
 523
 524/**
 525 * pdcs_size_read - Stable Storage size output.
 526 * @buf: The output buffer to write to.
 527 */
 528static ssize_t pdcs_size_read(struct kobject *kobj,
 529			      struct kobj_attribute *attr,
 530			      char *buf)
 531{
 532	char *out = buf;
 533
 534	if (!buf)
 535		return -EINVAL;
 536
 537	/* show the size of the stable storage */
 538	out += sprintf(out, "%ld\n", pdcs_size);
 539
 540	return out - buf;
 541}
 542
 543/**
 544 * pdcs_auto_read - Stable Storage autoboot/search flag output.
 545 * @buf: The output buffer to write to.
 546 * @knob: The PF_AUTOBOOT or PF_AUTOSEARCH flag
 547 */
 548static ssize_t pdcs_auto_read(struct kobject *kobj,
 549			      struct kobj_attribute *attr,
 550			      char *buf, int knob)
 551{
 552	char *out = buf;
 553	struct pdcspath_entry *pathentry;
 554
 555	if (!buf)
 556		return -EINVAL;
 557
 558	/* Current flags are stored in primary boot path entry */
 559	pathentry = &pdcspath_entry_primary;
 560
 561	read_lock(&pathentry->rw_lock);
 562	out += sprintf(out, "%s\n", (pathentry->devpath.flags & knob) ?
 563					"On" : "Off");
 564	read_unlock(&pathentry->rw_lock);
 565
 566	return out - buf;
 567}
 568
 569/**
 570 * pdcs_autoboot_read - Stable Storage autoboot flag output.
 571 * @buf: The output buffer to write to.
 572 */
 573static ssize_t pdcs_autoboot_read(struct kobject *kobj,
 574				  struct kobj_attribute *attr, char *buf)
 575{
 576	return pdcs_auto_read(kobj, attr, buf, PF_AUTOBOOT);
 577}
 578
 579/**
 580 * pdcs_autosearch_read - Stable Storage autoboot flag output.
 581 * @buf: The output buffer to write to.
 582 */
 583static ssize_t pdcs_autosearch_read(struct kobject *kobj,
 584				    struct kobj_attribute *attr, char *buf)
 585{
 586	return pdcs_auto_read(kobj, attr, buf, PF_AUTOSEARCH);
 587}
 588
 589/**
 590 * pdcs_timer_read - Stable Storage timer count output (in seconds).
 591 * @buf: The output buffer to write to.
 592 *
 593 * The value of the timer field correponds to a number of seconds in powers of 2.
 594 */
 595static ssize_t pdcs_timer_read(struct kobject *kobj,
 596			       struct kobj_attribute *attr, char *buf)
 597{
 598	char *out = buf;
 599	struct pdcspath_entry *pathentry;
 600
 601	if (!buf)
 602		return -EINVAL;
 603
 604	/* Current flags are stored in primary boot path entry */
 605	pathentry = &pdcspath_entry_primary;
 606
 607	/* print the timer value in seconds */
 608	read_lock(&pathentry->rw_lock);
 609	out += sprintf(out, "%u\n", (pathentry->devpath.flags & PF_TIMER) ?
 610				(1 << (pathentry->devpath.flags & PF_TIMER)) : 0);
 611	read_unlock(&pathentry->rw_lock);
 612
 613	return out - buf;
 614}
 615
 616/**
 617 * pdcs_osid_read - Stable Storage OS ID register output.
 618 * @buf: The output buffer to write to.
 619 */
 620static ssize_t pdcs_osid_read(struct kobject *kobj,
 621			      struct kobj_attribute *attr, char *buf)
 622{
 623	char *out = buf;
 624
 625	if (!buf)
 626		return -EINVAL;
 627
 628	out += sprintf(out, "%s dependent data (0x%.4x)\n",
 629		os_id_to_string(pdcs_osid), pdcs_osid);
 630
 631	return out - buf;
 632}
 633
 634/**
 635 * pdcs_osdep1_read - Stable Storage OS-Dependent data area 1 output.
 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 * @buf: The output buffer to write to.
 663 *
 664 * I have NFC how to interpret the content of that register ;-).
 665 */
 666static ssize_t pdcs_diagnostic_read(struct kobject *kobj,
 667				    struct kobj_attribute *attr, char *buf)
 668{
 669	char *out = buf;
 670	u32 result;
 671
 672	if (!buf)
 673		return -EINVAL;
 674
 675	/* get diagnostic */
 676	if (pdc_stable_read(PDCS_ADDR_DIAG, &result, sizeof(result)) != PDC_OK)
 677		return -EIO;
 678
 679	out += sprintf(out, "0x%.4x\n", (result >> 16));
 680
 681	return out - buf;
 682}
 683
 684/**
 685 * pdcs_fastsize_read - Stable Storage FastSize register output.
 686 * @buf: The output buffer to write to.
 687 *
 688 * This register holds the amount of system RAM to be tested during boot sequence.
 689 */
 690static ssize_t pdcs_fastsize_read(struct kobject *kobj,
 691				  struct kobj_attribute *attr, char *buf)
 692{
 693	char *out = buf;
 694	u32 result;
 695
 696	if (!buf)
 697		return -EINVAL;
 698
 699	/* get fast-size */
 700	if (pdc_stable_read(PDCS_ADDR_FSIZ, &result, sizeof(result)) != PDC_OK)
 701		return -EIO;
 702
 703	if ((result & 0x0F) < 0x0E)
 704		out += sprintf(out, "%d kB", (1<<(result & 0x0F))*256);
 705	else
 706		out += sprintf(out, "All");
 707	out += sprintf(out, "\n");
 708	
 709	return out - buf;
 710}
 711
 712/**
 713 * pdcs_osdep2_read - Stable Storage OS-Dependent data area 2 output.
 714 * @buf: The output buffer to write to.
 715 *
 716 * This can hold pdcs_size - 224 bytes of OS-Dependent data, when available.
 717 */
 718static ssize_t pdcs_osdep2_read(struct kobject *kobj,
 719				struct kobj_attribute *attr, char *buf)
 720{
 721	char *out = buf;
 722	unsigned long size;
 723	unsigned short i;
 724	u32 result;
 725
 726	if (unlikely(pdcs_size <= 224))
 727		return -ENODATA;
 728
 729	size = pdcs_size - 224;
 730
 731	if (!buf)
 732		return -EINVAL;
 733
 734	for (i=0; i<size; i+=4) {
 735		if (unlikely(pdc_stable_read(PDCS_ADDR_OSD2 + i, &result,
 736					sizeof(result)) != PDC_OK))
 737			return -EIO;
 738		out += sprintf(out, "0x%.8x\n", result);
 739	}
 740
 741	return out - buf;
 742}
 743
 744/**
 745 * pdcs_auto_write - This function handles autoboot/search flag modifying.
 746 * @buf: The input buffer to read from.
 747 * @count: The number of bytes to be read.
 748 * @knob: The PF_AUTOBOOT or PF_AUTOSEARCH flag
 749 * 
 750 * We will call this function to change the current autoboot flag.
 751 * We expect a precise syntax:
 752 *	\"n\" (n == 0 or 1) to toggle AutoBoot Off or On
 753 */
 754static ssize_t pdcs_auto_write(struct kobject *kobj,
 755			       struct kobj_attribute *attr, const char *buf,
 756			       size_t count, int knob)
 757{
 758	struct pdcspath_entry *pathentry;
 759	unsigned char flags;
 760	char in[count+1], *temp;
 761	char c;
 762
 763	if (!capable(CAP_SYS_ADMIN))
 764		return -EACCES;
 765
 766	if (!buf || !count)
 767		return -EINVAL;
 768
 769	/* We'll use a local copy of buf */
 770	memset(in, 0, count+1);
 771	strncpy(in, buf, count);
 772
 773	/* Current flags are stored in primary boot path entry */
 774	pathentry = &pdcspath_entry_primary;
 775	
 776	/* Be nice to the existing flag record */
 777	read_lock(&pathentry->rw_lock);
 778	flags = pathentry->devpath.flags;
 779	read_unlock(&pathentry->rw_lock);
 780	
 781	DPRINTK("%s: flags before: 0x%X\n", __func__, flags);
 782
 783	temp = skip_spaces(in);
 784
 785	c = *temp++ - '0';
 786	if ((c != 0) && (c != 1))
 787		goto parse_error;
 788	if (c == 0)
 789		flags &= ~knob;
 790	else
 791		flags |= knob;
 792	
 793	DPRINTK("%s: flags after: 0x%X\n", __func__, flags);
 794		
 795	/* So far so good, let's get in deep */
 796	write_lock(&pathentry->rw_lock);
 797	
 798	/* Change the path entry flags first */
 799	pathentry->devpath.flags = flags;
 800		
 801	/* Now, dive in. Write back to the hardware */
 802	pdcspath_store(pathentry);
 803	write_unlock(&pathentry->rw_lock);
 804	
 805	printk(KERN_INFO PDCS_PREFIX ": changed \"%s\" to \"%s\"\n",
 806		(knob & PF_AUTOBOOT) ? "autoboot" : "autosearch",
 807		(flags & knob) ? "On" : "Off");
 808	
 809	return count;
 810
 811parse_error:
 812	printk(KERN_WARNING "%s: Parse error: expect \"n\" (n == 0 or 1)\n", __func__);
 813	return -EINVAL;
 814}
 815
 816/**
 817 * pdcs_autoboot_write - This function handles autoboot flag modifying.
 818 * @buf: The input buffer to read from.
 819 * @count: The number of bytes to be read.
 820 *
 821 * We will call this function to change the current boot flags.
 822 * We expect a precise syntax:
 823 *	\"n\" (n == 0 or 1) to toggle AutoSearch Off or On
 824 */
 825static ssize_t pdcs_autoboot_write(struct kobject *kobj,
 826				   struct kobj_attribute *attr,
 827				   const char *buf, size_t count)
 828{
 829	return pdcs_auto_write(kobj, attr, buf, count, PF_AUTOBOOT);
 830}
 831
 832/**
 833 * pdcs_autosearch_write - This function handles autosearch flag modifying.
 834 * @buf: The input buffer to read from.
 835 * @count: The number of bytes to be read.
 836 *
 837 * We will call this function to change the current boot flags.
 838 * We expect a precise syntax:
 839 *	\"n\" (n == 0 or 1) to toggle AutoSearch Off or On
 840 */
 841static ssize_t pdcs_autosearch_write(struct kobject *kobj,
 842				     struct kobj_attribute *attr,
 843				     const char *buf, size_t count)
 844{
 845	return pdcs_auto_write(kobj, attr, buf, count, PF_AUTOSEARCH);
 846}
 847
 848/**
 849 * pdcs_osdep1_write - Stable Storage OS-Dependent data area 1 input.
 850 * @buf: The input buffer to read from.
 851 * @count: The number of bytes to be read.
 852 *
 853 * This can store 16 bytes of OS-Dependent data. We use a byte-by-byte
 854 * write approach. It's up to userspace to deal with it when constructing
 855 * its input buffer.
 856 */
 857static ssize_t pdcs_osdep1_write(struct kobject *kobj,
 858				 struct kobj_attribute *attr,
 859				 const char *buf, size_t count)
 860{
 861	u8 in[16];
 862
 863	if (!capable(CAP_SYS_ADMIN))
 864		return -EACCES;
 865
 866	if (!buf || !count)
 867		return -EINVAL;
 868
 869	if (unlikely(pdcs_osid != OS_ID_LINUX))
 870		return -EPERM;
 871
 872	if (count > 16)
 873		return -EMSGSIZE;
 874
 875	/* We'll use a local copy of buf */
 876	memset(in, 0, 16);
 877	memcpy(in, buf, count);
 878
 879	if (pdc_stable_write(PDCS_ADDR_OSD1, &in, sizeof(in)) != PDC_OK)
 880		return -EIO;
 881
 882	return count;
 883}
 884
 885/**
 886 * pdcs_osdep2_write - Stable Storage OS-Dependent data area 2 input.
 887 * @buf: The input buffer to read from.
 888 * @count: The number of bytes to be read.
 889 *
 890 * This can store pdcs_size - 224 bytes of OS-Dependent data. We use a
 891 * byte-by-byte write approach. It's up to userspace to deal with it when
 892 * constructing its input buffer.
 893 */
 894static ssize_t pdcs_osdep2_write(struct kobject *kobj,
 895				 struct kobj_attribute *attr,
 896				 const char *buf, size_t count)
 897{
 898	unsigned long size;
 899	unsigned short i;
 900	u8 in[4];
 901
 902	if (!capable(CAP_SYS_ADMIN))
 903		return -EACCES;
 904
 905	if (!buf || !count)
 906		return -EINVAL;
 907
 908	if (unlikely(pdcs_size <= 224))
 909		return -ENOSYS;
 910
 911	if (unlikely(pdcs_osid != OS_ID_LINUX))
 912		return -EPERM;
 913
 914	size = pdcs_size - 224;
 915
 916	if (count > size)
 917		return -EMSGSIZE;
 918
 919	/* We'll use a local copy of buf */
 920
 921	for (i=0; i<count; i+=4) {
 922		memset(in, 0, 4);
 923		memcpy(in, buf+i, (count-i < 4) ? count-i : 4);
 924		if (unlikely(pdc_stable_write(PDCS_ADDR_OSD2 + i, &in,
 925					sizeof(in)) != PDC_OK))
 926			return -EIO;
 927	}
 928
 929	return count;
 930}
 931
 932/* The remaining attributes. */
 933static PDCS_ATTR(size, 0444, pdcs_size_read, NULL);
 934static PDCS_ATTR(autoboot, 0644, pdcs_autoboot_read, pdcs_autoboot_write);
 935static PDCS_ATTR(autosearch, 0644, pdcs_autosearch_read, pdcs_autosearch_write);
 936static PDCS_ATTR(timer, 0444, pdcs_timer_read, NULL);
 937static PDCS_ATTR(osid, 0444, pdcs_osid_read, NULL);
 938static PDCS_ATTR(osdep1, 0600, pdcs_osdep1_read, pdcs_osdep1_write);
 939static PDCS_ATTR(diagnostic, 0400, pdcs_diagnostic_read, NULL);
 940static PDCS_ATTR(fastsize, 0400, pdcs_fastsize_read, NULL);
 941static PDCS_ATTR(osdep2, 0600, pdcs_osdep2_read, pdcs_osdep2_write);
 942
 943static struct attribute *pdcs_subsys_attrs[] = {
 944	&pdcs_attr_size.attr,
 945	&pdcs_attr_autoboot.attr,
 946	&pdcs_attr_autosearch.attr,
 947	&pdcs_attr_timer.attr,
 948	&pdcs_attr_osid.attr,
 949	&pdcs_attr_osdep1.attr,
 950	&pdcs_attr_diagnostic.attr,
 951	&pdcs_attr_fastsize.attr,
 952	&pdcs_attr_osdep2.attr,
 953	NULL,
 954};
 955
 956static struct attribute_group pdcs_attr_group = {
 957	.attrs = pdcs_subsys_attrs,
 958};
 959
 960static struct kobject *stable_kobj;
 961static struct kset *paths_kset;
 962
 963/**
 964 * pdcs_register_pathentries - Prepares path entries kobjects for sysfs usage.
 965 * 
 966 * It creates kobjects corresponding to each path entry with nice sysfs
 967 * links to the real device. This is where the magic takes place: when
 968 * registering the subsystem attributes during module init, each kobject hereby
 969 * created will show in the sysfs tree as a folder containing files as defined
 970 * by path_subsys_attr[].
 971 */
 972static inline int __init
 973pdcs_register_pathentries(void)
 974{
 975	unsigned short i;
 976	struct pdcspath_entry *entry;
 977	int err;
 978	
 979	/* Initialize the entries rw_lock before anything else */
 980	for (i = 0; (entry = pdcspath_entries[i]); i++)
 981		rwlock_init(&entry->rw_lock);
 982
 983	for (i = 0; (entry = pdcspath_entries[i]); i++) {
 984		write_lock(&entry->rw_lock);
 985		err = pdcspath_fetch(entry);
 986		write_unlock(&entry->rw_lock);
 987
 988		if (err < 0)
 989			continue;
 990
 991		entry->kobj.kset = paths_kset;
 992		err = kobject_init_and_add(&entry->kobj, &ktype_pdcspath, NULL,
 993					   "%s", entry->name);
 994		if (err)
 995			return err;
 996
 997		/* kobject is now registered */
 998		write_lock(&entry->rw_lock);
 999		entry->ready = 2;
1000		
1001		/* Add a nice symlink to the real device */
1002		if (entry->dev) {
1003			err = sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
1004			WARN_ON(err);
1005		}
1006
1007		write_unlock(&entry->rw_lock);
1008		kobject_uevent(&entry->kobj, KOBJ_ADD);
1009	}
1010	
1011	return 0;
1012}
1013
1014/**
1015 * pdcs_unregister_pathentries - Routine called when unregistering the module.
1016 */
1017static inline void
1018pdcs_unregister_pathentries(void)
1019{
1020	unsigned short i;
1021	struct pdcspath_entry *entry;
1022	
1023	for (i = 0; (entry = pdcspath_entries[i]); i++) {
1024		read_lock(&entry->rw_lock);
1025		if (entry->ready >= 2)
1026			kobject_put(&entry->kobj);
1027		read_unlock(&entry->rw_lock);
1028	}
1029}
1030
1031/*
1032 * For now we register the stable subsystem with the firmware subsystem
1033 * and the paths subsystem with the stable subsystem
1034 */
1035static int __init
1036pdc_stable_init(void)
1037{
1038	int rc = 0, error = 0;
1039	u32 result;
1040
1041	/* find the size of the stable storage */
1042	if (pdc_stable_get_size(&pdcs_size) != PDC_OK) 
1043		return -ENODEV;
1044
1045	/* make sure we have enough data */
1046	if (pdcs_size < 96)
1047		return -ENODATA;
1048
1049	printk(KERN_INFO PDCS_PREFIX " facility v%s\n", PDCS_VERSION);
1050
1051	/* get OSID */
1052	if (pdc_stable_read(PDCS_ADDR_OSID, &result, sizeof(result)) != PDC_OK)
1053		return -EIO;
1054
1055	/* the actual result is 16 bits away */
1056	pdcs_osid = (u16)(result >> 16);
1057
1058	/* For now we'll register the directory at /sys/firmware/stable */
1059	stable_kobj = kobject_create_and_add("stable", firmware_kobj);
1060	if (!stable_kobj) {
1061		rc = -ENOMEM;
1062		goto fail_firmreg;
1063	}
1064
1065	/* Don't forget the root entries */
1066	error = sysfs_create_group(stable_kobj, &pdcs_attr_group);
1067
1068	/* register the paths kset as a child of the stable kset */
1069	paths_kset = kset_create_and_add("paths", NULL, stable_kobj);
1070	if (!paths_kset) {
1071		rc = -ENOMEM;
1072		goto fail_ksetreg;
1073	}
1074
1075	/* now we create all "files" for the paths kset */
1076	if ((rc = pdcs_register_pathentries()))
1077		goto fail_pdcsreg;
1078
1079	return rc;
1080	
1081fail_pdcsreg:
1082	pdcs_unregister_pathentries();
1083	kset_unregister(paths_kset);
1084	
1085fail_ksetreg:
1086	kobject_put(stable_kobj);
1087	
1088fail_firmreg:
1089	printk(KERN_INFO PDCS_PREFIX " bailing out\n");
1090	return rc;
1091}
1092
1093static void __exit
1094pdc_stable_exit(void)
1095{
1096	pdcs_unregister_pathentries();
1097	kset_unregister(paths_kset);
1098	kobject_put(stable_kobj);
1099}
1100
1101
1102module_init(pdc_stable_init);
1103module_exit(pdc_stable_exit);