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/*
* Interfaces to retrieve and set PDC Stable options (firmware)
*
* Copyright (C) 2005-2006 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, version 2, as
* published by the Free Software Foundation.
*
* 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 just 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.
*
* The current policy wrt file permissions is:
* - write: root only
* - read: (reading triggers PDC calls) ? root only : everyone
* The rationale is that PDC calls could hog (DoS) the machine.
*
* TODO:
* - timer/fastsize write calls
*/
#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/kernel.h>
#include <linux/string.h>
#include <linux/capability.h>
#include <linux/ctype.h>
#include <linux/sysfs.h>
#include <linux/kobject.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/spinlock.h>
#include <asm/pdc.h>
#include <asm/page.h>
#include <asm/uaccess.h>
#include <asm/hardware.h>
#define PDCS_VERSION "0.22"
#define PDCS_PREFIX "PDC Stable Storage"
#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);
/* holds Stable Storage size. Initialized once and for all, no lock needed */
static unsigned long pdcs_size __read_mostly;
/* This struct defines what we need to deal with a parisc pdc path entry */
struct pdcspath_entry {
rwlock_t rw_lock; /* to protect path entry access */
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.
*
* This function expects to be called with @entry->rw_lock write-hold.
*/
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
*
* This function expects to be called with @entry->rw_lock write-hold.
*/
static void
pdcspath_store(struct pdcspath_entry *entry)
{
struct device_path *devpath;
BUG_ON(!entry);
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 */
BUG_ON(!entry->dev);
device_to_hwpath(entry->dev, (struct hardware_path *)devpath);
}
/* 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__);
WARN_ON(1);
}
/* kobject is already registered */
entry->ready = 2;
DPRINTK("%s: device: 0x%p\n", __func__, entry->dev);
}
/**
* 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;
short i;
if (!entry || !buf)
return -EINVAL;
read_lock(&entry->rw_lock);
devpath = &entry->devpath;
i = entry->ready;
read_unlock(&entry->rw_lock);
if (!i) /* entry is not ready */
|