[PATCH] PA-RISC PDC stable storage driver

Add PDC stable storage driver.  Also reorganise PA-RISC Kconfig a little.
Signed-off-by: Thibaut VARENE <varenet@parisc-linux.org>
Signed-off-by: Matthew Wilcox <willy@parisc-linux.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/parisc/Kconfig

@@ -110,6 +110,14 @@ config IOMMU_SBA
 #	help
 #	  Say Y here for V-class PCI, DMA/IOMMU, IRQ subsystem support.
 
+source "drivers/pcmcia/Kconfig"
+
+source "drivers/pci/hotplug/Kconfig"
+
+endmenu
+
+menu "PA-RISC specific drivers"
+
 config SUPERIO
 	bool "SuperIO (SuckyIO) support"
 	depends on PCI_LBA
@@ -144,9 +152,18 @@ config PDC_CHASSIS
 	  
 	  If unsure, say Y.
 
-source "drivers/pcmcia/Kconfig"
+config PDC_STABLE
+	tristate "PDC Stable Storage support"
+	depends on SYSFS
+	default y
+	help
+	  Say Y here if you want to enable support for accessing Stable Storage
+	  variables (PDC non volatile variables such as Primary Boot Path,
+	  Console Path, Autoboot, Autosearch, etc) through SysFS.
 	
-source "drivers/pci/hotplug/Kconfig"
+	  If unsure, say Y.
 	
+	  To compile this driver as a module, choose M here.
+	  The module will be called pdc_stable.
 
 endmenu

drivers/parisc/Makefile

@@ -22,5 +22,6 @@ obj-$(CONFIG_EISA)		+= eisa.o eisa_enumerator.o eisa_eeprom.o
 
 obj-$(CONFIG_SUPERIO)		+= superio.o
 obj-$(CONFIG_CHASSIS_LCD_LED)	+= led.o
+obj-$(CONFIG_PDC_STABLE)	+= pdc_stable.o
 obj-y				+= power.o
 

drivers/parisc/pdc_stable.c

+/* 
+ *    Interfaces to retrieve and set PDC Stable options (firmware)
+ *
+ *    Copyright (C) 2005 Thibaut VARENE <varenet@parisc-linux.org>
+ *
+ *    This program is free software; you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation; either version 2 of the License, or
+ *    (at your option) any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *
+ *    DEV NOTE: the PDC Procedures reference states that:
+ *    "A minimum of 96 bytes of Stable Storage is required. Providing more than
+ *    96 bytes of Stable Storage is optional [...]. Failure to provide the
+ *    optional locations from 96 to 192 results in the loss of certain
+ *    functionality during boot."
+ *
+ *    Since locations between 96 and 192 are the various paths, most (if not
+ *    all) PA-RISC machines should have them. Anyway, for safety reasons, the
+ *    following code can deal with only 96 bytes of Stable Storage, and all
+ *    sizes between 96 and 192 bytes (provided they are multiple of struct
+ *    device_path size, eg: 128, 160 and 192) to provide full information.
+ *    The code makes no use of data above 192 bytes. One last word: there's one
+ *    path we can always count on: the primary path.
+ */
+
+#undef PDCS_DEBUG
+#ifdef PDCS_DEBUG
+#define DPRINTK(fmt, args...)	printk(KERN_DEBUG fmt, ## args)
+#else
+#define DPRINTK(fmt, args...)
+#endif
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>		/* for capable() */
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+
+#include <asm/pdc.h>
+#include <asm/page.h>
+#include <asm/uaccess.h>
+#include <asm/hardware.h>
+
+#define PDCS_VERSION	"0.09"
+
+#define PDCS_ADDR_PPRI	0x00
+#define PDCS_ADDR_OSID	0x40
+#define PDCS_ADDR_FSIZ	0x5C
+#define PDCS_ADDR_PCON	0x60
+#define PDCS_ADDR_PALT	0x80
+#define PDCS_ADDR_PKBD	0xA0
+
+MODULE_AUTHOR("Thibaut VARENE <varenet@parisc-linux.org>");
+MODULE_DESCRIPTION("sysfs interface to HP PDC Stable Storage data");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(PDCS_VERSION);
+
+static unsigned long pdcs_size = 0;
+
+/* This struct defines what we need to deal with a parisc pdc path entry */
+struct pdcspath_entry {
+	short ready;			/* entry record is valid if != 0 */
+	unsigned long addr;		/* entry address in stable storage */
+	char *name;			/* entry name */
+	struct device_path devpath;	/* device path in parisc representation */
+	struct device *dev;		/* corresponding device */
+	struct kobject kobj;
+};
+
+struct pdcspath_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct pdcspath_entry *entry, char *buf);
+	ssize_t (*store)(struct pdcspath_entry *entry, const char *buf, size_t count);
+};
+
+#define PDCSPATH_ENTRY(_addr, _name) \
+struct pdcspath_entry pdcspath_entry_##_name = { \
+	.ready = 0, \
+	.addr = _addr, \
+	.name = __stringify(_name), \
+};
+
+#define PDCS_ATTR(_name, _mode, _show, _store) \
+struct subsys_attribute pdcs_attr_##_name = { \
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
+	.show = _show, \
+	.store = _store, \
+};
+
+#define PATHS_ATTR(_name, _mode, _show, _store) \
+struct pdcspath_attribute paths_attr_##_name = { \
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
+	.show = _show, \
+	.store = _store, \
+};
+
+#define to_pdcspath_attribute(_attr) container_of(_attr, struct pdcspath_attribute, attr)
+#define to_pdcspath_entry(obj)  container_of(obj, struct pdcspath_entry, kobj)
+
+/**
+ * pdcspath_fetch - This function populates the path entry structs.
+ * @entry: A pointer to an allocated pdcspath_entry.
+ * 
+ * The general idea is that you don't read from the Stable Storage every time
+ * you access the files provided by the facilites. We store a copy of the
+ * content of the stable storage WRT various paths in these structs. We read
+ * these structs when reading the files, and we will write to these structs when
+ * writing to the files, and only then write them back to the Stable Storage.
+ */
+static int
+pdcspath_fetch(struct pdcspath_entry *entry)
+{
+	struct device_path *devpath;
+
+	if (!entry)
+		return -EINVAL;
+
+	devpath = &entry->devpath;
+	
+	DPRINTK("%s: fetch: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
+			entry, devpath, entry->addr);
+
+	/* addr, devpath and count must be word aligned */
+	if (pdc_stable_read(entry->addr, devpath, sizeof(*devpath)) != PDC_OK)
+		return -EIO;
+		
+	/* Find the matching device.
+	   NOTE: hardware_path overlays with device_path, so the nice cast can
+	   be used */
+	entry->dev = hwpath_to_device((struct hardware_path *)devpath);
+
+	entry->ready = 1;
+	
+	DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
+	
+	return 0;
+}
+
+/**
+ * pdcspath_store - This function writes a path to stable storage.
+ * @entry: A pointer to an allocated pdcspath_entry.
+ * 
+ * It can be used in two ways: either by passing it a preset devpath struct
+ * containing an already computed hardware path, or by passing it a device
+ * pointer, from which it'll find out the corresponding hardware path.
+ * For now we do not handle the case where there's an error in writing to the
+ * Stable Storage area, so you'd better not mess up the data :P
+ */
+static int
+pdcspath_store(struct pdcspath_entry *entry)
+{
+	struct device_path *devpath;
+
+	if (!entry)
+		return -EINVAL;
+
+	devpath = &entry->devpath;
+	
+	/* We expect the caller to set the ready flag to 0 if the hardware
+	   path struct provided is invalid, so that we know we have to fill it.
+	   First case, we don't have a preset hwpath... */
+	if (!entry->ready) {
+		/* ...but we have a device, map it */
+		if (entry->dev)
+			device_to_hwpath(entry->dev, (struct hardware_path *)devpath);
+		else
+			return -EINVAL;
+	}
+	/* else, we expect the provided hwpath to be valid. */
+	
+	DPRINTK("%s: store: 0x%p, 0x%p, addr: 0x%lx\n", __func__,
+			entry, devpath, entry->addr);
+
+	/* addr, devpath and count must be word aligned */
+	if (pdc_stable_write(entry->addr, devpath, sizeof(*devpath)) != PDC_OK) {
+		printk(KERN_ERR "%s: an error occured when writing to PDC.\n"
+				"It is likely that the Stable Storage data has been corrupted.\n"
+				"Please check it carefully upon next reboot.\n", __func__);
+		return -EIO;
+	}
+		
+	entry->ready = 1;
+	
+	DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
+	
+	return 0;
+}
+
+/**
+ * pdcspath_hwpath_read - This function handles hardware path pretty printing.
+ * @entry: An allocated and populated pdscpath_entry struct.
+ * @buf: The output buffer to write to.
+ * 
+ * We will call this function to format the output of the hwpath attribute file.
+ */
+static ssize_t
+pdcspath_hwpath_read(struct pdcspath_entry *entry, char *buf)
+{
+	char *out = buf;
+	struct device_path *devpath;
+	unsigned short i;
+
+	if (!entry || !buf)
+		return -EINVAL;
+
+	devpath = &entry->devpath;
+
+	if (!entry->ready)
+		return -ENODATA;
+	
+	for (i = 0; i < 6; i++) {
+		if (devpath->bc[i] >= 128)
+			continue;
+		out += sprintf(out, "%u/", (unsigned char)devpath->bc[i]);
+	}
+	out += sprintf(out, "%u\n", (unsigned char)devpath->mod);
+	
+	return out - buf;
+}
+
+/**
+ * pdcspath_hwpath_write - This function handles hardware path modifying.
+ * @entry: An allocated and populated pdscpath_entry struct.
+ * @buf: The input buffer to read from.
+ * @count: The number of bytes to be read.
+ * 
+ * We will call this function to change the current hardware path.
+ * Hardware paths are to be given '/'-delimited, without brackets.
+ * We take care to make sure that the provided path actually maps to an existing
+ * device, BUT nothing would prevent some foolish user to set the path to some
+ * PCI bridge or even a CPU...
+ * A better work around would be to make sure we are at the end of a device tree
+ * for instance, but it would be IMHO beyond the simple scope of that driver.
+ * The aim is to provide a facility. Data correctness is left to userland.
+ */
+static ssize_t
+pdcspath_hwpath_write(struct pdcspath_entry *entry, const char *buf, size_t count)
+{
+	struct hardware_path hwpath;
+	unsigned short i;
+	char in[count+1], *temp;
+	struct device *dev;
+
+	if (!entry || !buf || !count)
+		return -EINVAL;
+
+	/* We'll use a local copy of buf */
+	memset(in, 0, count+1);
+	strncpy(in, buf, count);
+	
+	/* Let's clean up the target. 0xff is a blank pattern */
+	memset(&hwpath, 0xff, sizeof(hwpath));
+	
+	/* First, pick the mod field (the last one of the input string) */
+	if (!(temp = strrchr(in, '/')))
+		return -EINVAL;
+			
+	hwpath.mod = simple_strtoul(temp+1, NULL, 10);
+	in[temp-in] = '\0';	/* truncate the remaining string. just precaution */
+	DPRINTK("%s: mod: %d\n", __func__, hwpath.mod);
+	
+	/* Then, loop for each delimiter, making sure we don't have too many.
+	   we write the bc fields in a down-top way. No matter what, we stop
+	   before writing the last field. If there are too many fields anyway,
+	   then the user is a moron and it'll be caught up later when we'll
+	   check the consistency of the given hwpath. */
+	for (i=5; ((temp = strrchr(in, '/'))) && (temp-in > 0) && (likely(i)); i--) {
+		hwpath.bc[i] = simple_strtoul(temp+1, NULL, 10);
+		in[temp-in] = '\0';
+		DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.bc[i]);
+	}
+	
+	/* Store the final field */		
+	hwpath.bc[i] = simple_strtoul(in, NULL, 10);
+	DPRINTK("%s: bc[%d]: %d\n", __func__, i, hwpath.bc[i]);
+	
+	/* Now we check that the user isn't trying to lure us */
+	if (!(dev = hwpath_to_device((struct hardware_path *)&hwpath))) {
+		printk(KERN_WARNING "%s: attempt to set invalid \"%s\" "
+			"hardware path: %s\n", __func__, entry->name, buf);
+		return -EINVAL;
+	}
+	
+	/* So far so good, let's get in deep */
+	entry->ready = 0;
+	entry->dev = dev;
+	
+	/* Now, dive in. Write back to the hardware */
+	WARN_ON(pdcspath_store(entry));	/* this warn should *NEVER* happen */
+	
+	/* Update the symlink to the real device */
+	sysfs_remove_link(&entry->kobj, "device");
+	sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
+	
+	printk(KERN_INFO "PDC Stable Storage: changed \"%s\" path to \"%s\"\n",
+		entry->name, buf);
+	
+	return count;
+}
+
+/**
+ * pdcspath_layer_read - Extended layer (eg. SCSI ids) pretty printing.
+ * @entry: An allocated and populated pdscpath_entry struct.
+ * @buf: The output buffer to write to.
+ * 
+ * We will call this function to format the output of the layer attribute file.
+ */
+static ssize_t
+pdcspath_layer_read(struct pdcspath_entry *entry, char *buf)
+{
+	char *out = buf;
+	struct device_path *devpath;
+	unsigned short i;
+
+	if (!entry || !buf)
+		return -EINVAL;
+	
+	devpath = &entry->devpath;
+
+	if (!entry->ready)
+		return -ENODATA;
+	
+	for (i = 0; devpath->layers[i] && (likely(i < 6)); i++)
+		out += sprintf(out, "%u ", devpath->layers[i]);
+
+	out += sprintf(out, "\n");
+	
+	return out - buf;
+}
+
+/**
+ * pdcspath_layer_write - This function handles extended layer modifying.
+ * @entry: An allocated and populated pdscpath_entry struct.
+ * @buf: The input buffer to read from.
+ * @count: The number of bytes to be read.
+ * 
+ * We will call this function to change the current layer value.
+ * Layers are to be given '.'-delimited, without brackets.
+ * XXX beware we are far less checky WRT input data provided than for hwpath.
+ * Potential harm can be done, since there's no way to check the validity of
+ * the layer fields.
+ */
+static ssize_t
+pdcspath_layer_write(struct pdcspath_entry *entry, const char *buf, size_t count)
+{
+	unsigned int layers[6]; /* device-specific info (ctlr#, unit#, ...) */
+	unsigned short i;
+	char in[count+1], *temp;
+
+	if (!entry || !buf || !count)
+		return -EINVAL;
+
+	/* We'll use a local copy of buf */
+	memset(in, 0, count+1);
+	strncpy(in, buf, count);
+	
+	/* Let's clean up the target. 0 is a blank pattern */
+	memset(&layers, 0, sizeof(layers));
+	
+	/* First, pick the first layer */
+	if (unlikely(!isdigit(*in)))
+		return -EINVAL;
+	layers[0] = simple_strtoul(in, NULL, 10);
+	DPRINTK("%s: layer[0]: %d\n", __func__, layers[0]);
+	
+	temp = in;
+	for (i=1; ((temp = strchr(temp, '.'))) && (likely(i<6)); i++) {
+		if (unlikely(!isdigit(*(++temp))))
+			return -EINVAL;
+		layers[i] = simple_strtoul(temp, NULL, 10);
+		DPRINTK("%s: layer[%d]: %d\n", __func__, i, layers[i]);
+	}
+		
+	/* So far so good, let's get in deep */
+	
+	/* First, overwrite the current layers with the new ones, not touching
+	   the hardware path. */
+	memcpy(&entry->devpath.layers, &layers, sizeof(layers));
+	
+	/* Now, dive in. Write back to the hardware */
+	WARN_ON(pdcspath_store(entry));	/* this warn should *NEVER* happen */
+	
+	printk(KERN_INFO "PDC Stable Storage: changed \"%s\" layers to \"%s\"\n",
+		entry->name, buf);
+	
+	return count;
+}
+
+/**
+ * pdcspath_attr_show - Generic read function call wrapper.
+ * @kobj: The kobject to get info from.
+ * @attr: The attribute looked upon.
+ * @buf: The output buffer.
+ */
+static ssize_t
+pdcspath_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+	struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
+	struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
+	ssize_t ret = 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (pdcs_attr->show)
+		ret = pdcs_attr->show(entry, buf);
+
+	return ret;
+}
+
+/**
+ * pdcspath_attr_store - Generic write function call wrapper.
+ * @kobj: The kobject to write info to.
+ * @attr: The attribute to be modified.
+ * @buf: The input buffer.
+ * @count: The size of the buffer.
+ */
+static ssize_t
+pdcspath_attr_store(struct kobject *kobj, struct attribute *attr,
+			const char *buf, size_t count)
+{
+	struct pdcspath_entry *entry = to_pdcspath_entry(kobj);
+	struct pdcspath_attribute *pdcs_attr = to_pdcspath_attribute(attr);
+	ssize_t ret = 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (pdcs_attr->store)
+		ret = pdcs_attr->store(entry, buf, count);
+
+	return ret;
+}
+
+static struct sysfs_ops pdcspath_attr_ops = {
+	.show = pdcspath_attr_show,
+	.store = pdcspath_attr_store,
+};
+
+/* These are the two attributes of any PDC path. */
+static PATHS_ATTR(hwpath, 0600, pdcspath_hwpath_read, pdcspath_hwpath_write);
+static PATHS_ATTR(layer, 0600, pdcspath_layer_read, pdcspath_layer_write);
+
+static struct attribute *paths_subsys_attrs[] = {
+	&paths_attr_hwpath.attr,
+	&paths_attr_layer.attr,
+	NULL,
+};
+
+/* Specific kobject type for our PDC paths */
+static struct kobj_type ktype_pdcspath = {
+	.sysfs_ops = &pdcspath_attr_ops,
+	.default_attrs = paths_subsys_attrs,
+};
+
+/* We hard define the 4 types of path we expect to find */
+static PDCSPATH_ENTRY(PDCS_ADDR_PPRI, primary);
+static PDCSPATH_ENTRY(PDCS_ADDR_PCON, console);
+static PDCSPATH_ENTRY(PDCS_ADDR_PALT, alternative);
+static PDCSPATH_ENTRY(PDCS_ADDR_PKBD, keyboard);
+
+/* An array containing all PDC paths we will deal with */
+static struct pdcspath_entry *pdcspath_entries[] = {
+	&pdcspath_entry_primary,
+	&pdcspath_entry_alternative,
+	&pdcspath_entry_console,
+	&pdcspath_entry_keyboard,
+	NULL,
+};
+
+/**
+ * pdcs_info_read - Pretty printing of the remaining useful data.
+ * @entry: An allocated and populated subsytem struct. We don't use it tho.
+ * @buf: The output buffer to write to.
+ * 
+ * We will call this function to format the output of the 'info' attribute file.
+ * Please refer to PDC Procedures documentation, section PDC_STABLE to get a
+ * better insight of what we're doing here.
+ */
+static ssize_t
+pdcs_info_read(struct subsystem *entry, char *buf)
+{
+	char *out = buf;
+	__u32 result;
+	struct device_path devpath;
+	char *tmpstr = NULL;
+	
+	if (!entry || !buf)
+		return -EINVAL;
+		
+	/* show the size of the stable storage */
+	out += sprintf(out, "Stable Storage size: %ld bytes\n", pdcs_size);
+
+	/* deal with flags */
+	if (pdc_stable_read(PDCS_ADDR_PPRI, &devpath, sizeof(devpath)) != PDC_OK)
+		return -EIO;
+	
+	out += sprintf(out, "Autoboot: %s\n", (devpath.flags & PF_AUTOBOOT) ? "On" : "Off");
+	out += sprintf(out, "Autosearch: %s\n", (devpath.flags & PF_AUTOSEARCH) ? "On" : "Off");
+	out += sprintf(out, "Timer: %u s\n", (devpath.flags & PF_TIMER) ? (1 << (devpath.flags & PF_TIMER)) : 0);
+
+	/* get OSID */
+	if (pdc_stable_read(PDCS_ADDR_OSID, &result, sizeof(result)) != PDC_OK)
+		return -EIO;
+
+	/* the actual result is 16 bits away */
+	switch (result >> 16) {
+		case 0x0000:	tmpstr = "No OS-dependent data"; break;
+		case 0x0001:	tmpstr = "HP-UX dependent data"; break;
+		case 0x0002:	tmpstr = "MPE-iX dependent data"; break;
+		case 0x0003:	tmpstr = "OSF dependent data"; break;
+		case 0x0004:	tmpstr = "HP-RT dependent data"; break;
+		case 0x0005:	tmpstr = "Novell Netware dependent data"; break;
+		default:	tmpstr = "Unknown"; break;
+	}
+	out += sprintf(out, "OS ID: %s (0x%.4x)\n", tmpstr, (result >> 16));
+
+	/* get fast-size */
+	if (pdc_stable_read(PDCS_ADDR_FSIZ, &result, sizeof(result)) != PDC_OK)
+		return -EIO;
+
+	out += sprintf(out, "Memory tested: ");
+	if ((result & 0x0F) < 0x0E)
+		out += sprintf(out, "%.3f MB", 0.256*(1<<(result & 0x0F)));
+	else
+		out += sprintf(out, "All");
+	out += sprintf(out, "\n");
+	
+	return out - buf;
+}
+
+/**
+ * pdcs_info_write - This function handles boot flag modifying.
+ * @entry: An allocated and populated subsytem struct. We don't use it tho.
+ * @buf: The input buffer to read from.
+ * @count: The number of bytes to be read.
+ * 
+ * We will call this function to change the current boot flags.
+ * We expect a precise syntax:
+ *	\"n n\" (n == 0 or 1) to toggle respectively AutoBoot and AutoSearch
+ *
+ * As of now there is no incentive on my side to provide more "knobs" to that
+ * interface, since modifying the rest of the data is pretty meaningless when
+ * the machine is running and for the expected use of that facility, such as
+ * PALO setting up the boot disk when installing a Linux distribution...
+ */
+static ssize_t
+pdcs_info_write(struct subsystem *entry, const char *buf, size_t count)
+{
+	struct pdcspath_entry *pathentry;
+	unsigned char flags;
+	char in[count+1], *temp;
+	char c;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (!entry || !buf || !count)
+		return -EINVAL;
+
+	/* We'll use a local copy of buf */
+	memset(in, 0, count+1);
+	strncpy(in, buf, count);
+
+	/* Current flags are stored in primary boot path entry */
+	pathentry = &pdcspath_entry_primary;
+	
+	/* Be nice to the existing flag record */
+	flags = pathentry->devpath.flags;
+	
+	DPRINTK("%s: flags before: 0x%X\n", __func__, flags);
+			
+	temp = in;
+	
+	while (*temp && isspace(*temp))
+		temp++;
+	
+	c = *temp++ - '0';
+	if ((c != 0) && (c != 1))
+		goto parse_error;
+	if (c == 0)
+		flags &= ~PF_AUTOBOOT;
+	else
+		flags |= PF_AUTOBOOT;
+	
+	if (*temp++ != ' ')
+		goto parse_error;
+	
+	c = *temp++ - '0';
+	if ((c != 0) && (c != 1))
+		goto parse_error;
+	if (c == 0)
+		flags &= ~PF_AUTOSEARCH;
+	else
+		flags |= PF_AUTOSEARCH;
+	
+	DPRINTK("%s: flags after: 0x%X\n", __func__, flags);
+		
+	/* So far so good, let's get in deep */
+	
+	/* Change the path entry flags first */
+	pathentry->devpath.flags = flags;
+		
+	/* Now, dive in. Write back to the hardware */
+	WARN_ON(pdcspath_store(pathentry));	/* this warn should *NEVER* happen */
+	
+	printk(KERN_INFO "PDC Stable Storage: changed flags to \"%s\"\n", buf);
+	
+	return count;
+
+parse_error:
+	printk(KERN_WARNING "%s: Parse error: expect \"n n\" (n == 0 or 1) for AB and AS\n", __func__);
+	return -EINVAL;
+}
+
+/* The last attribute (the 'root' one actually) with all remaining data. */
+static PDCS_ATTR(info, 0600, pdcs_info_read, pdcs_info_write);
+
+static struct subsys_attribute *pdcs_subsys_attrs[] = {
+	&pdcs_attr_info,
+	NULL,	/* maybe more in the future? */
+};
+
+static decl_subsys(paths, &ktype_pdcspath, NULL);
+static decl_subsys(pdc, NULL, NULL);
+
+/**
+ * pdcs_register_pathentries - Prepares path entries kobjects for sysfs usage.
+ * 
+ * It creates kobjects corresponding to each path entry with nice sysfs
+ * links to the real device. This is where the magic takes place: when
+ * registering the subsystem attributes during module init, each kobject hereby
+ * created will show in the sysfs tree as a folder containing files as defined
+ * by path_subsys_attr[].
+ */
+static inline int __init
+pdcs_register_pathentries(void)
+{
+	unsigned short i;
+	struct pdcspath_entry *entry;
+	
+	for (i = 0; (entry = pdcspath_entries[i]); i++) {
+		if (pdcspath_fetch(entry) < 0)
+			continue;
+
+		kobject_set_name(&entry->kobj, "%s", entry->name);
+		kobj_set_kset_s(entry, paths_subsys);
+		kobject_register(&entry->kobj);
+
+		if (!entry->dev)
+			continue;
+
+		/* Add a nice symlink to the real device */
+		sysfs_create_link(&entry->kobj, &entry->dev->kobj, "device");
+	}
+	
+	return 0;
+}
+
+/**
+ * pdcs_unregister_pathentries - Routine called when unregistering the module.
+ */
+static inline void __exit
+pdcs_unregister_pathentries(void)
+{
+	unsigned short i;
+	struct pdcspath_entry *entry;
+	
+	for (i = 0; (entry = pdcspath_entries[i]); i++)
+		if (entry->ready)
+			kobject_unregister(&entry->kobj);	
+}
+
+/*
+ * For now we register the pdc subsystem with the firmware subsystem
+ * and the paths subsystem with the pdc subsystem
+ */
+static int __init
+pdc_stable_init(void)
+{
+	struct subsys_attribute *attr;
+	int i, rc = 0, error = 0;
+
+	/* find the size of the stable storage */
+	if (pdc_stable_get_size(&pdcs_size) != PDC_OK) 
+		return -ENODEV;
+
+	printk(KERN_INFO "PDC Stable Storage facility v%s\n", PDCS_VERSION);
+
+	/* For now we'll register the pdc subsys within this driver */
+	if ((rc = firmware_register(&pdc_subsys)))
+		return rc;
+
+	/* Don't forget the info entry */
+	for (i = 0; (attr = pdcs_subsys_attrs[i]) && !error; i++)
+		if (attr->show)
+			error = subsys_create_file(&pdc_subsys, attr);
+	
+	/* register the paths subsys as a subsystem of pdc subsys */
+	kset_set_kset_s(&paths_subsys, pdc_subsys);
+	subsystem_register(&paths_subsys);
+
+	/* now we create all "files" for the paths subsys */
+	pdcs_register_pathentries();
+	
+	return 0;
+}
+
+static void __exit
+pdc_stable_exit(void)
+{
+	pdcs_unregister_pathentries();
+	subsystem_unregister(&paths_subsys);
+
+	firmware_unregister(&pdc_subsys);
+}
+
+
+module_init(pdc_stable_init);
+module_exit(pdc_stable_exit);