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/*

 * CMOS/NV-RAM driver for Linux

 *

 * Copyright (C) 1997 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>

 * idea by and with help from Richard Jelinek <rj@suse.de>

 * Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com)

 *

 * This driver allows you to access the contents of the non-volatile memory in

 * the mc146818rtc.h real-time clock. This chip is built into all PCs and into

 * many Atari machines. In the former it's called "CMOS-RAM", in the latter

 * "NVRAM" (NV stands for non-volatile).

 *

 * The data are supplied as a (seekable) character device, /dev/nvram. The

 * size of this file is dependant on the controller.  The usual size is 114,

 * the number of freely available bytes in the memory (i.e., not used by the

 * RTC itself).

 *

 * Checksums over the NVRAM contents are managed by this driver. In case of a

 * bad checksum, reads and writes return -EIO. The checksum can be initialized

 * to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or

 * ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid

 * again; use with care!)

 *

 * This file also provides some functions for other parts of the kernel that

 * want to access the NVRAM: nvram_{read,write,check_checksum,set_checksum}.

 * Obviously this can be used only if this driver is always configured into

 * the kernel and is not a module. Since the functions are used by some Atari

 * drivers, this is the case on the Atari.

 *

 *

 *      1.1     Cesar Barros: SMP locking fixes

 *              added changelog

 *      1.2     Erik Gilling: Cobalt Networks support

 *              Tim Hockin: general cleanup, Cobalt support

 */

#define NVRAM_VERSION   "1.2"

#include <linux/module.h>

#include <linux/config.h>

#include <linux/sched.h>

#include <linux/smp_lock.h>

#include <linux/nvram.h>

#define PC              1

#define ATARI           2

#define COBALT          3

/* select machine configuration */

#if defined(CONFIG_ATARI)

#  define MACH ATARI

#elif defined(__i386__) || defined(__x86_64__) || defined(__arm__)  /* and others?? */

#define MACH PC

#  if defined(CONFIG_COBALT)

#    include <linux/cobalt-nvram.h>

#    define MACH COBALT

#  else

#    define MACH PC

#  endif

#else

#  error Cannot build nvram driver for this machine configuration.

#endif

#if MACH == PC

/* RTC in a PC */

#define CHECK_DRIVER_INIT()     1

/* On PCs, the checksum is built only over bytes 2..31 */

#define PC_CKS_RANGE_START      2

#define PC_CKS_RANGE_END        31

#define PC_CKS_LOC              32

#define NVRAM_BYTES             (128-NVRAM_FIRST_BYTE)

#define mach_check_checksum     pc_check_checksum

#define mach_set_checksum       pc_set_checksum

#define mach_proc_infos         pc_proc_infos

#endif

#if MACH == COBALT

#define CHECK_DRIVER_INIT()     1

#define NVRAM_BYTES             (128-NVRAM_FIRST_BYTE)

#define mach_check_checksum     cobalt_check_checksum

#define mach_set_checksum       cobalt_set_checksum

#define mach_proc_infos         cobalt_proc_infos

#endif

#if MACH == ATARI

/* Special parameters for RTC in Atari machines */

#include <asm/atarihw.h>

#include <asm/atariints.h>

#define RTC_PORT(x)             (TT_RTC_BAS + 2*(x))

#define CHECK_DRIVER_INIT()     (MACH_IS_ATARI && ATARIHW_PRESENT(TT_CLK))

#define NVRAM_BYTES             50

/* On Ataris, the checksum is over all bytes except the checksum bytes

 * themselves; these are at the very end */

#define ATARI_CKS_RANGE_START   0

#define ATARI_CKS_RANGE_END     47

#define ATARI_CKS_LOC           48

#define mach_check_checksum     atari_check_checksum

#define mach_set_checksum       atari_set_checksum

#define mach_proc_infos         atari_proc_infos

#endif

/* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with

 * rtc_lock held. Due to the index-port/data-port design of the RTC, we

 * don't want two different things trying to get to it at once. (e.g. the

 * periodic 11 min sync from time.c vs. this driver.)

 */

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/miscdevice.h>

#include <linux/slab.h>

#include <linux/ioport.h>

#include <linux/fcntl.h>

#include <linux/mc146818rtc.h>

#include <linux/init.h>

#include <linux/proc_fs.h>

#include <linux/spinlock.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#include <asm/system.h>

static spinlock_t nvram_state_lock = SPIN_LOCK_UNLOCKED;

static int nvram_open_cnt;      /* #times opened */

static int nvram_open_mode;     /* special open modes */

#define NVRAM_WRITE             1 /* opened for writing (exclusive) */

#define NVRAM_EXCL              2 /* opened with O_EXCL */

static int mach_check_checksum(void);

static void mach_set_checksum(void);

#ifdef CONFIG_PROC_FS

static int mach_proc_infos(unsigned char *contents, char *buffer, int *len,

    off_t *begin, off_t offset, int size);

#endif

/*

 * These functions are provided to be called internally or by other parts of

 * the kernel. It's up to the caller to ensure correct checksum before reading

 * or after writing (needs to be done only once).

 *

 * It is worth noting that these functions all access bytes of general

 * purpose memory in the NVRAM - that is to say, they all add the

 * NVRAM_FIRST_BYTE offset.  Pass them offsets into NVRAM as if you did not

 * know about the RTC cruft.

 */

unsigned char

__nvram_read_byte(int i)

{

        return CMOS_READ(NVRAM_FIRST_BYTE + i);

}

unsigned char

nvram_read_byte(int i)

{

        unsigned long flags;

        unsigned char c;

        spin_lock_irqsave(&rtc_lock, flags);

        c = __nvram_read_byte(i);

        spin_unlock_irqrestore(&rtc_lock, flags);

        return c;

}

/* This races nicely with trying to read with checksum checking (nvram_read) */

void

__nvram_write_byte(unsigned char c, int i)

{

        CMOS_WRITE(c, NVRAM_FIRST_BYTE + i);

}

void

nvram_write_byte(unsigned char c, int i)

{

        unsigned long flags;

        spin_lock_irqsave(&rtc_lock, flags);

        __nvram_write_byte(c, i);

        spin_unlock_irqrestore(&rtc_lock, flags);

}

int

__nvram_check_checksum(void)

{

        return mach_check_checksum();

}

int

nvram_check_checksum(void)

{

        unsigned long flags;

        int rv;

        spin_lock_irqsave(&rtc_lock, flags);

        rv = __nvram_check_checksum();

        spin_unlock_irqrestore(&rtc_lock, flags);

        return rv;

}

void

__nvram_set_checksum(void)

{

        mach_set_checksum();

}

void

nvram_set_checksum(void)

{

        unsigned long flags;

        spin_lock_irqsave(&rtc_lock, flags);

        __nvram_set_checksum();

        spin_unlock_irqrestore(&rtc_lock, flags);

}

/*

 * The are the file operation function for user access to /dev/nvram

 */

static long long

nvram_llseek(struct file *file, loff_t offset, int origin)

{

        switch (origin) {

        case 0:

                /* nothing to do */

                break;

        case 1:

                offset += file->f_pos;

                break;

        case 2:

                offset += NVRAM_BYTES;

                break;

        }

        return (offset >= 0) ? (file->f_pos = offset) : -EINVAL;

}

static ssize_t

nvram_read(struct file *file, char *buf, size_t count, loff_t *ppos)

{

        unsigned char contents[NVRAM_BYTES];

        unsigned i = *ppos;

        unsigned char *tmp;

        spin_lock_irq(&rtc_lock);

        if (!__nvram_check_checksum())

                goto checksum_err;

        for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)

                *tmp = __nvram_read_byte(i);

        spin_unlock_irq(&rtc_lock);

        if (copy_to_user(buf, contents, tmp - contents))

                return -EFAULT;

        *ppos = i;

        return tmp - contents;

      checksum_err:

        spin_unlock_irq(&rtc_lock);

        return -EIO;

}

static ssize_t

nvram_write(struct file *file, const char *buf, size_t count, loff_t *ppos)

{

        unsigned char contents[NVRAM_BYTES];

        unsigned i = *ppos;

        unsigned char *tmp;

        int len;

        len = (NVRAM_BYTES - i) < count ? (NVRAM_BYTES - i) : count;

        if (copy_from_user(contents, buf, len))

                return -EFAULT;

        spin_lock_irq(&rtc_lock);

        if (!__nvram_check_checksum())

                goto checksum_err;

        for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)

                __nvram_write_byte(*tmp, i);

        __nvram_set_checksum();

        spin_unlock_irq(&rtc_lock);

        *ppos = i;

        return tmp - contents;

      checksum_err:

        spin_unlock_irq(&rtc_lock);

        return -EIO;

}

static int

nvram_ioctl(struct inode *inode, struct file *file,

    unsigned int cmd, unsigned long arg)

{

        int i;

        switch (cmd) {

        case NVRAM_INIT:

                /* initialize NVRAM contents and checksum */

                if (!capable(CAP_SYS_ADMIN))

                        return -EACCES;

                spin_lock_irq(&rtc_lock);

                for (i = 0; i < NVRAM_BYTES; ++i)

                        __nvram_write_byte(0, i);

                __nvram_set_checksum();

                spin_unlock_irq(&rtc_lock);

                return 0;

        case NVRAM_SETCKS:

                /* just set checksum, contents unchanged (maybe useful after

                 * checksum garbaged somehow...) */

                if (!capable(CAP_SYS_ADMIN))

                        return -EACCES;

                spin_lock_irq(&rtc_lock);

                __nvram_set_checksum();

                spin_unlock_irq(&rtc_lock);

                return 0;

        default:

                return -ENOTTY;

        }

}

static int

nvram_open(struct inode *inode, struct file *file)

{

        spin_lock(&nvram_state_lock);

        if ((nvram_open_cnt && (file->f_flags & O_EXCL)) ||

            (nvram_open_mode & NVRAM_EXCL) ||

            ((file->f_mode & 2) && (nvram_open_mode & NVRAM_WRITE))) {

                spin_unlock(&nvram_state_lock);

                return -EBUSY;

        }

        if (file->f_flags & O_EXCL)

                nvram_open_mode |= NVRAM_EXCL;

        if (file->f_mode & 2)

                nvram_open_mode |= NVRAM_WRITE;

        nvram_open_cnt++;

        spin_unlock(&nvram_state_lock);

        return 0;

}

static int

nvram_release(struct inode *inode, struct file *file)

{

        spin_lock(&nvram_state_lock);

        nvram_open_cnt--;

        /* if only one instance is open, clear the EXCL bit */

        if (nvram_open_mode & NVRAM_EXCL)

                nvram_open_mode &= ~NVRAM_EXCL;

        if (file->f_mode & 2)

                nvram_open_mode &= ~NVRAM_WRITE;

        spin_unlock(&nvram_state_lock);

        return 0;

}

#ifndef CONFIG_PROC_FS

static int

nvram_read_proc(char *buffer, char **start, off_t offset,

    int size, int *eof, void *data)

{

        return 0;

}

#else

static int

nvram_read_proc(char *buffer, char **start, off_t offset,

    int size, int *eof, void *data)

{

        unsigned char contents[NVRAM_BYTES];

        int i, len = 0;

        off_t begin = 0;

        spin_lock_irq(&rtc_lock);

        for (i = 0; i < NVRAM_BYTES; ++i)

                contents[i] = __nvram_read_byte(i);

        spin_unlock_irq(&rtc_lock);

        *eof = mach_proc_infos(contents, buffer, &len, &begin, offset, size);

        if (offset >= begin + len)

                return 0;

        *start = buffer + (offset - begin);

        return (size < begin + len - offset) ? size : begin + len - offset;

}

/* This macro frees the machine specific function from bounds checking and

 * this like that... */

#define PRINT_PROC(fmt,args...)                                 \

        do {                                                    \

                *len += sprintf(buffer+*len, fmt, ##args);      \

                if (*begin + *len > offset + size)              \

                        return 0;                                \

                if (*begin + *len < offset) {                   \

                        *begin += *len;                         \

                        *len = 0;                                \

                }                                               \

        } while(0)

#endif /* CONFIG_PROC_FS */

static struct file_operations nvram_fops = {

        owner:          THIS_MODULE,

        llseek:         nvram_llseek,

        read:           nvram_read,

        write:          nvram_write,

        ioctl:          nvram_ioctl,

        open:           nvram_open,

        release:        nvram_release,

};

static struct miscdevice nvram_dev = {

        NVRAM_MINOR,

        "nvram",

        &nvram_fops

};

static int __init

nvram_init(void)

{

        int ret;

        /* First test whether the driver should init at all */

        if (!CHECK_DRIVER_INIT())

                return -ENXIO;

        ret = misc_register(&nvram_dev);

        if (ret) {

                printk(KERN_ERR "nvram: can't misc_register on minor=%d\n",

                    NVRAM_MINOR);

                goto out;

        }

        if (!create_proc_read_entry("driver/nvram", 0, 0, nvram_read_proc,

                NULL)) {

                printk(KERN_ERR "nvram: can't create /proc/driver/nvram\n");

                ret = -ENOMEM;

                goto outmisc;

        }

        ret = 0;

        printk(KERN_INFO "Non-volatile memory driver v" NVRAM_VERSION "\n");

      out:

        return ret;

      outmisc:

        misc_deregister(&nvram_dev);

        goto out;

}

static void __exit

nvram_cleanup_module(void)

{

        remove_proc_entry("driver/nvram", 0);

        misc_deregister(&nvram_dev);

}

module_init(nvram_init);

module_exit(nvram_cleanup_module);

/*

 * Machine specific functions

 */

#if MACH == PC

static int

pc_check_checksum(void)

{

        int i;

        unsigned short sum = 0;

        unsigned short expect;

        for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i)

                sum += __nvram_read_byte(i);

        expect = __nvram_read_byte(PC_CKS_LOC)<<8 |

            __nvram_read_byte(PC_CKS_LOC+1);

        return ((sum & 0xffff) == expect);

}

static void

pc_set_checksum(void)

{

        int i;

        unsigned short sum = 0;

        for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i)

                sum += __nvram_read_byte(i);

        __nvram_write_byte(sum >> 8, PC_CKS_LOC);

        __nvram_write_byte(sum & 0xff, PC_CKS_LOC + 1);

}

#ifdef CONFIG_PROC_FS

static char *floppy_types[] = {

        "none", "5.25'' 360k", "5.25'' 1.2M", "3.5'' 720k", "3.5'' 1.44M",

        "3.5'' 2.88M", "3.5'' 2.88M"

};

static char *gfx_types[] = {

        "EGA, VGA, ... (with BIOS)",

        "CGA (40 cols)",

        "CGA (80 cols)",

        "monochrome",

};

static int

pc_proc_infos(unsigned char *nvram, char *buffer, int *len,

    off_t *begin, off_t offset, int size)

{

        int checksum;

        int type;

        spin_lock_irq(&rtc_lock);

        checksum = __nvram_check_checksum();

        spin_unlock_irq(&rtc_lock);

        PRINT_PROC("Checksum status: %svalid\n", checksum ? "" : "not ");

        PRINT_PROC("# floppies     : %d\n",

            (nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0);

        PRINT_PROC("Floppy 0 type  : ");

        type = nvram[2] >> 4;

        if (type < sizeof (floppy_types) / sizeof (*floppy_types))

                PRINT_PROC("%s\n", floppy_types[type]);

        else

                PRINT_PROC("%d (unknown)\n", type);

        PRINT_PROC("Floppy 1 type  : ");

        type = nvram[2] & 0x0f;

        if (type < sizeof (floppy_types) / sizeof (*floppy_types))

                PRINT_PROC("%s\n", floppy_types[type]);

        else

                PRINT_PROC("%d (unknown)\n", type);

        PRINT_PROC("HD 0 type      : ");

        type = nvram[4] >> 4;

        if (type)

                PRINT_PROC("%02x\n", type == 0x0f ? nvram[11] : type);

        else

                PRINT_PROC("none\n");

        PRINT_PROC("HD 1 type      : ");

        type = nvram[4] & 0x0f;

        if (type)

                PRINT_PROC("%02x\n", type == 0x0f ? nvram[12] : type);

        else

                PRINT_PROC("none\n");

        PRINT_PROC("HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d\n",

            nvram[18] | (nvram[19] << 8),

            nvram[20], nvram[25],

            nvram[21] | (nvram[22] << 8), nvram[23] | (nvram[24] << 8));

        PRINT_PROC("HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d\n",

            nvram[39] | (nvram[40] << 8),

            nvram[41], nvram[46],

            nvram[42] | (nvram[43] << 8), nvram[44] | (nvram[45] << 8));

        PRINT_PROC("DOS base memory: %d kB\n", nvram[7] | (nvram[8] << 8));

        PRINT_PROC("Extended memory: %d kB (configured), %d kB (tested)\n",

            nvram[9] | (nvram[10] << 8), nvram[34] | (nvram[35] << 8));

        PRINT_PROC("Gfx adapter    : %s\n", gfx_types[(nvram[6] >> 4) & 3]);

        PRINT_PROC("FPU            : %sinstalled\n",

            (nvram[6] & 2) ? "" : "not ");

        return 1;

}

#endif

#endif /* MACH == PC */

#if MACH == COBALT

/* the cobalt CMOS has a wider range of it's checksum */

static int cobalt_check_checksum(void)

{

        int i;

        unsigned short sum = 0;

        unsigned short expect;

        for (i = COBT_CMOS_CKS_START; i <= COBT_CMOS_CKS_END; ++i) {

                if ((i == COBT_CMOS_CHECKSUM) || (i == (COBT_CMOS_CHECKSUM+1)))

                        continue;

                sum += __nvram_read_byte(i);

        }

        expect = __nvram_read_byte(COBT_CMOS_CHECKSUM) << 8 |

            __nvram_read_byte(COBT_CMOS_CHECKSUM+1);

        return ((sum & 0xffff) == expect);

}

static void cobalt_set_checksum(void)

{

        int i;

        unsigned short sum = 0;

        for (i = COBT_CMOS_CKS_START; i <= COBT_CMOS_CKS_END; ++i) {

                if ((i == COBT_CMOS_CHECKSUM) || (i == (COBT_CMOS_CHECKSUM+1)))

                        continue;

                sum += __nvram_read_byte(i);

        }

        __nvram_write_byte(sum >> 8, COBT_CMOS_CHECKSUM);

        __nvram_write_byte(sum & 0xff, COBT_CMOS_CHECKSUM+1);

}

#ifdef CONFIG_PROC_FS

static int cobalt_proc_infos(unsigned char *nvram, char *buffer, int *len,

        off_t *begin, off_t offset, int size)

{

        int i;

        unsigned int checksum;

        unsigned int flags;

        char sernum[14];

        char *key = "cNoEbTaWlOtR!";

        unsigned char bto_csum;

        spin_lock_irq(&rtc_lock);

        checksum = __nvram_check_checksum();

        spin_unlock_irq(&rtc_lock);

        PRINT_PROC("Checksum status: %svalid\n", checksum ? "" : "not ");

        flags = nvram[COBT_CMOS_FLAG_BYTE_0] << 8

            | nvram[COBT_CMOS_FLAG_BYTE_1];

        PRINT_PROC("Console: %s\n",

                flags & COBT_CMOS_CONSOLE_FLAG ?  "on": "off");

        PRINT_PROC("Firmware Debug Messages: %s\n",

                flags & COBT_CMOS_DEBUG_FLAG ? "on": "off");

        PRINT_PROC("Auto Prompt: %s\n",

                flags & COBT_CMOS_AUTO_PROMPT_FLAG ? "on": "off");

        PRINT_PROC("Shutdown Status: %s\n",

                flags & COBT_CMOS_CLEAN_BOOT_FLAG ? "clean": "dirty");

        PRINT_PROC("Hardware Probe: %s\n",

                flags & COBT_CMOS_HW_NOPROBE_FLAG ? "partial": "full");

        PRINT_PROC("System Fault: %sdetected\n",

                flags & COBT_CMOS_SYSFAULT_FLAG ? "": "not ");

        PRINT_PROC("Panic on OOPS: %s\n",