linux-imx

// SPDX-License-Identifier: GPL-2.0-only

/* 

 *    Interfaces to retrieve and set PDC Stable options (firmware)

 *

 *    Copyright (C) 2005-2006 Thibaut VARENE <varenet@parisc-linux.org>

 *

 *    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.

 *    One last word: there's one path we can always count on: the primary path.

 *    Anything above 224 bytes is used for 'osdep2' OS-dependent storage area.

 *

 *    The first OS-dependent area should always be available. Obviously, this is

 *    not true for the other one. Also bear in mind that reading/writing from/to

 *    osdep2 is much more expensive than from/to osdep1.

 *    NOTE: We do not handle the 2 bytes OS-dep area at 0x5D, nor the first

 *    2 bytes of storage available right after OSID. That's a total of 4 bytes

 *    sacrificed: -ETOOLAZY :P

 *

 *    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 <linux/uaccess.h>

#include <asm/hardware.h>

​

#define PDCS_VERSION    "0.30"

#define PDCS_PREFIX "PDC Stable Storage"

​

#define PDCS_ADDR_PPRI  0x00

#define PDCS_ADDR_OSID  0x40

#define PDCS_ADDR_OSD1  0x48

#define PDCS_ADDR_DIAG  0x58

#define PDCS_ADDR_FSIZ  0x5C

#define PDCS_ADDR_PCON  0x60

#define PDCS_ADDR_PALT  0x80

#define PDCS_ADDR_PKBD  0xA0

#define PDCS_ADDR_OSD2  0xE0

​

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;

​

/* holds OS ID. Initialized once and for all, hopefully to 0x0006 */

static u16 pdcs_osid __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 */