/*
 *  c 2001 PPC 64 Team, IBM Corp
 *
 *      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.
 *
 * /dev/nvram driver for PPC64
 *
 * This perhaps should live in drivers/char
 */


#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/kmsg_dump.h>
#include <linux/pstore.h>
#include <linux/ctype.h>
#include <linux/zlib.h>
#include <asm/uaccess.h>
#include <asm/nvram.h>
#include <asm/rtas.h>
#include <asm/prom.h>
#include <asm/machdep.h>

/* Max bytes to read/write in one go */
#define NVRW_CNT 0x20

/*
 * Set oops header version to distinguish between old and new format header.
 * lnx,oops-log partition max size is 4000, header version > 4000 will
 * help in identifying new header.
 */
#define OOPS_HDR_VERSION 5000

static unsigned int nvram_size;
static int nvram_fetch, nvram_store;
static char nvram_buf[NVRW_CNT];        /* assume this is in the first 4GB */
static DEFINE_SPINLOCK(nvram_lock);

struct err_log_info {
        __be32 error_type;
        __be32 seq_num;
};

struct nvram_os_partition {
        const char *name;
        int req_size;   /* desired size, in bytes */
        int min_size;   /* minimum acceptable size (0 means req_size) */
        long size;      /* size of data portion (excluding err_log_info) */
        long index;     /* offset of data portion of partition */
        bool os_partition; /* partition initialized by OS, not FW */
};

static struct nvram_os_partition rtas_log_partition = {
        .name = "ibm,rtas-log",
        .req_size = 2079,
        .min_size = 1055,
        .index = -1,
        .os_partition = true
};

static struct nvram_os_partition oops_log_partition = {
        .name = "lnx,oops-log",
        .req_size = 4000,
        .min_size = 2000,
        .index = -1,
        .os_partition = true
};

static const char *pseries_nvram_os_partitions[] = {
        "ibm,rtas-log",
        "lnx,oops-log",
        NULL
};

struct oops_log_info {
        __be16 version;
        __be16 report_length;
        __be64 timestamp;
} __attribute__((packed));

static void oops_to_nvram(struct kmsg_dumper *dumper,
                          enum kmsg_dump_reason reason);

static struct kmsg_dumper nvram_kmsg_dumper = {
        .dump = oops_to_nvram
};

/* See clobbering_unread_rtas_event() */
#define NVRAM_RTAS_READ_TIMEOUT 5               /* seconds */
static unsigned long last_unread_rtas_event;    /* timestamp */

/*
 * For capturing and compressing an oops or panic report...

 * big_oops_buf[] holds the uncompressed text we're capturing.
 *
 * oops_buf[] holds the compressed text, preceded by a oops header.
 * oops header has u16 holding the version of oops header (to differentiate
 * between old and new format header) followed by u16 holding the length of
 * the compressed* text (*Or uncompressed, if compression fails.) and u64
 * holding the timestamp. oops_buf[] gets written to NVRAM.
 *
 * oops_log_info points to the header. oops_data points to the compressed text.
 *
 * +- oops_buf
 * |                                   +- oops_data
 * v                                   v
 * +-----------+-----------+-----------+------------------------+
 * | version   | length    | timestamp | text                   |
 * | (2 bytes) | (2 bytes) | (8 bytes) | (oops_data_sz bytes)   |
 * +-----------+-----------+-----------+------------------------+
 * ^
 * +- oops_log_info
 *
 * We preallocate these buffers during init to avoid kmalloc during oops/panic.
 */
static size_t big_oops_buf_sz;
static char *big_oops_buf, *oops_buf;
static char *oops_data;
static size_t oops_data_sz;

/* Compression parameters */
#define COMPR_LEVEL 6
#define WINDOW_BITS 12
#define MEM_LEVEL 4
static struct z_stream_s stream;

#ifdef CONFIG_PSTORE
static struct nvram_os_partition of_config_partition = {
        .name = "of-config",
        .index = -1,
        .os_partition = false
};

static struct nvram_os_partition common_partition = {
        .name = "common",
        .index = -1,
        .os_partition = false
};

static enum pstore_type_id nvram_type_ids[] = {
        PSTORE_TYPE_DMESG,
        PSTORE_TYPE_PPC_RTAS,
        PSTORE_TYPE_PPC_OF,
        PSTORE_TYPE_PPC_COMMON,
        -1
};
static int read_type;
static unsigned long last_rtas_event;
#endif

static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
{
        unsigned int i;
        unsigned long len;
        int done;
        unsigned long flags;
        char *p = buf;


        if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
                return -ENODEV;

        if (*index >= nvram_size)
                return 0;

        i = *index;
        if (i + count > nvram_size)
                count = nvram_size - i;

        spin_lock_irqsave(&nvram_lock, flags);

        for (; count != 0; count -= len) {
                len = count;
                if (len > NVRW_CNT)
                        len = NVRW_CNT;
                
                if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
                               len) != 0) || len != done) {
                        spin_unlock_irqrestore(&nvram_lock, flags);
                        return -EIO;
                }
                
                memcpy(p, nvram_buf, len);

                p += len;
                i += len;
        }

        spin_unlock_irqrestore(&nvram_lock, flags);
        
        *index = i;
        return p - buf;
}

static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
{
        unsigned int i;
        unsigned long len;
        int done;
        unsigned long flags;
        const char *p = buf;

        if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
                return -ENODEV;

        if (*index >= nvram_size)
                return 0;

        i = *index;
        if (i + count > nvram_size)
                count = nvram_size - i;

        spin_lock_irqsave(&nvram_lock, flags);

        for (; count != 0; count -= len) {
                len = count;
                if (len > NVRW_CNT)
                        len = NVRW_CNT;

                memcpy(nvram_buf, p, len);

                if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
                               len) != 0) || len != done) {
                        spin_unlock_irqrestore(&nvram_lock, flags);
                        return -EIO;
                }
                
                p += len;
                i += len;
        }
        spin_unlock_irqrestore(&nvram_lock, flags);
        
        *index = i;
        return p - buf;
}

static ssize_t pSeries_nvram_get_size(void)
{
        return nvram_size ? nvram_size : -ENODEV;
}


/* nvram_write_os_partition, nvram_write_error_log
 *
 * We need to buffer the error logs into nvram to ensure that we have
 * the failure information to decode.  If we have a severe error there
 * is no way to guarantee that the OS or the machine is in a state to
 * get back to user land and write the error to disk.  For example if
 * the SCSI device driver causes a Machine Check by writing to a bad
 * IO address, there is no way of guaranteeing that the device driver
 * is in any state that is would also be able to write the error data
 * captured to disk, thus we buffer it in NVRAM for analysis on the
 * next boot.
 *
 * In NVRAM the partition containing the error log buffer will looks like:
 * Header (in bytes):
 * +-----------+----------+--------+------------+------------------+
 * | signature | checksum | length | name       | data             |
 * |0          |1         |2      3|4         15|16        length-1|
 * +-----------+----------+--------+------------+------------------+
 *
 * The 'data' section would look like (in bytes):
 * +--------------+------------+-----------------------------------+
 * | event_logged | sequence # | error log                         |
 * |0            3|4          7|8                  error_log_size-1|
 * +--------------+------------+-----------------------------------+
 *
 * event_logged: 0 if event has not been logged to syslog, 1 if it has
 * sequence #: The unique sequence # for each event. (until it wraps)
 * error log: The error log from event_scan
 */
int nvram_write_os_partition(struct nvram_os_partition *part, char * buff,
                int length, unsigned int err_type, unsigned int error_log_cnt)
{
        int rc;
        loff_t tmp_index;
        struct err_log_info info;
        
        if (part->index == -1) {
                return -ESPIPE;
        }

        if (length > part->size) {
                length = part->size;
        }

        info.error_type = cpu_to_be32(err_type);
        info.seq_num = cpu_to_be32(error_log_cnt);

        tmp_index = part->index;

        rc = ppc_md.nvram_write((char *)&info, sizeof(struct err_log_info), &tmp_index);
        if (rc <= 0) {
                pr_err("%s: Failed nvram_write (%d)\n", __FUNCTION__, rc);
                return rc;
        }

        rc = ppc_md.nvram_write(buff, length, &tmp_index);
        if (rc <= 0) {
                pr_err("%s: Failed nvram_write (%d)\n", __FUNCTION__, rc);
                return rc;
        }
        
        return 0;
}

int nvram_write_error_log(char * buff, int length,
                          unsigned int err_type, unsigned int error_log_cnt)
{
        int rc = nvram_write_os_partition(&rtas_log_partition, buff, length,
                                                err_type, error_log_cnt);
        if (!rc) {
                last_unread_rtas_event = get_seconds();
#ifdef CONFIG_PSTORE
                last_rtas_event = get_seconds();
#endif
        }

        return rc;
}

/* nvram_read_partition
 *
 * Reads nvram partition for at most 'length'
 */
int nvram_read_partition(struct nvram_os_partition *part, char *buff,
                        int length, unsigned int *err_type,
                        unsigned int *error_log_cnt)
{
        int rc;
        loff_t tmp_index;
        struct err_log_info info;
        
        if (part->index == -1)
                return -1;

        if (length > part->size)
                length = part->size;

        tmp_index = part->index;

        if (part->os_partition) {
                rc = ppc_md.nvram_read((char *)&info,
                                        sizeof(struct err_log_info),
                                        &tmp_index);
                if (rc <= 0) {
                        pr_err("%s: Failed nvram_read (%d)\n", __FUNCTION__,
                                                                        rc);
                        return rc;
                }
        }

        rc = ppc_md.nvram_read(buff, length, &tmp_index);
        if (rc <= 0) {
                pr_err("%s: Failed nvram_read (%d)\n", __FUNCTION__, rc);
                return rc;
        }

        if (part->os_partition) {
                *error_log_cnt = be32_to_cpu(info.seq_num);
                *err_type = be32_to_cpu(info.error_type);
        }

        return 0;
}

/* nvram_read_error_log
 *
 * Reads nvram for error log for at most 'length'
 */
int nvram_read_error_log(char *buff, int length,
                        unsigned int *err_type, unsigned int *error_log_cnt)
{
        return nvram_read_partition(&rtas_log_partition, buff, length,
                                                err_type, error_log_cnt);
}

/* This doesn't actually zero anything, but it sets the event_logged
 * word to tell that this event is safely in syslog.
 */
int nvram_clear_error_log(void)
{
        loff_t tmp_index;
        int clear_word = ERR_FLAG_ALREADY_LOGGED;
        int rc;

        if (rtas_log_partition.index == -1)
                return -1;

        tmp_index = rtas_log_partition.index;
        
        rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
        if (rc <= 0) {
                printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n", rc);
                return rc;
        }
        last_unread_rtas_event = 0;

        return 0;
}

/* pseries_nvram_init_os_partition
 *
 * This sets up a partition with an "OS" signature.
 *
 * The general strategy is the following:
 * 1.) If a partition with the indicated name already exists...
 *      - If it's large enough, use it.
 *      - Otherwise, recycle it and keep going.
 * 2.) Search for a free partition that is large enough.
 * 3.) If there's not a free partition large enough, recycle any obsolete
 * OS partitions and try again.
 * 4.) Will first try getting a chunk that will satisfy the requested size.
 * 5.) If a chunk of the requested size cannot be allocated, then try finding
 * a chunk that will satisfy the minum needed.
 *
 * Returns 0 on success, else -1.
 */
static int __init pseries_nvram_init_os_partition(struct nvram_os_partition
                                                                        *part)
{
        loff_t p;
        int size;

        /* Look for ours */
        p = nvram_find_partition(part->name, NVRAM_SIG_OS, &size);

        /* Found one but too small, remove it */
        if (p && size < part->min_size) {
                pr_info("nvram: Found too small %s partition,"
                                        " removing it...\n", part->name);
                nvram_remove_partition(part->name, NVRAM_SIG_OS, NULL);
                p = 0;
        }

        /* Create one if we didn't find */
        if (!p) {
                p = nvram_create_partition(part->name, NVRAM_SIG_OS,
                                        part->req_size, part->min_size);
                if (p == -ENOSPC) {
                        pr_info("nvram: No room to create %s partition, "
                                "deleting any obsolete OS partitions...\n",
                                part->name);
                        nvram_remove_partition(NULL, NVRAM_SIG_OS,
                                                pseries_nvram_os_partitions);
                        p = nvram_create_partition(part->name, NVRAM_SIG_OS,
                                        part->req_size, part->min_size);
                }
        }

        if (p <= 0) {
                pr_err("nvram: Failed to find or create %s"
                       " partition, err %d\n", part->name, (int)p);
                return -1;
        }

        part->index = p;
        part->size = nvram_get_partition_size(p) - sizeof(struct err_log_info);
        
        return 0;
}

/*
 * Are we using the ibm,rtas-log for oops/panic reports?  And if so,
 * would logging this oops/panic overwrite an RTAS event that rtas_errd
 * hasn't had a chance to read and process?  Return 1 if so, else 0.
 *
 * We assume that if rtas_errd hasn't read the RTAS event in
 * NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.
 */
static int clobbering_unread_rtas_event(void)
{
        return (oops_log_partition.index == rtas_log_partition.index
                && last_unread_rtas_event
                && get_seconds() - last_unread_rtas_event <=
                                                NVRAM_RTAS_READ_TIMEOUT);
}

/* Derived from logfs_compress() */
static int nvram_compress(const void *in, void *out, size_t inlen,
                                                        size_t outlen)
{
        int err, ret;

        ret = -EIO;
        err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
                                                MEM_LEVEL, Z_DEFAULT_STRATEGY);
        if (err != Z_OK)
                goto error;

        stream.next_in = in;
        stream.avail_in = inlen;
        stream.total_in = 0;
        stream.next_out = out;
        stream.avail_out = outlen;
        stream.total_out = 0;

        err = zlib_deflate(&stream, Z_FINISH);
        if (err != Z_STREAM_END)
                goto error;

        err = zlib_deflateEnd(&stream);
        if (err != Z_OK)
                goto error;

        if (stream.total_out >= stream.total_in)
                goto error;

        ret = stream.total_out;
error:
        return ret;
}

/* Compress the text from big_oops_buf into oops_buf. */
static int zip_oops(size_t text_len)
{
        struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
        int zipped_len = nvram_compress(big_oops_buf, oops_data, text_len,
                                                                oops_data_sz);
        if (zipped_len < 0) {
                pr_err("nvram: compression failed; returned %d\n", zipped_len);
                pr_err("nvram: logging uncompressed oops/panic report\n");
                return -1;
        }
        oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION);
        oops_hdr->report_length = cpu_to_be16(zipped_len);
        oops_hdr->timestamp = cpu_to_be64(get_seconds());
        return 0;
}

#ifdef CONFIG_PSTORE
static int nvram_pstore_open(struct pstore_info *psi)
{
        /* Reset the iterator to start reading partitions again */
        read_type = -1;
        return 0;
}

/**
 * nvram_pstore_write - pstore write callback for nvram
 * @type:               Type of message logged
 * @reason:             reason behind dump (oops/panic)
 * @id:                 identifier to indicate the write performed
 * @part:               pstore writes data to registered buffer in parts,
 *                      part number will indicate the same.
 * @count:              Indicates oops count
 * @compressed:         Flag to indicate the log is compressed
 * @size:               number of bytes written to the registered buffer
 * @psi:                registered pstore_info structure
 *
 * Called by pstore_dump() when an oops or panic report is logged in the
 * printk buffer.
 * Returns 0 on successful write.
 */
static int nvram_pstore_write(enum pstore_type_id type,
                                enum kmsg_dump_reason reason,
                                u64 *id, unsigned int part, int count,
                                bool compressed, size_t size,
                                struct pstore_info *psi)
{
        int rc;
        unsigned int err_type = ERR_TYPE_KERNEL_PANIC;
        struct oops_log_info *oops_hdr = (struct oops_log_info *) oops_buf;

        /* part 1 has the recent messages from printk buffer */
        if (part > 1 || type != PSTORE_TYPE_DMESG ||
                                clobbering_unread_rtas_event())
                return -1;

        oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION);
        oops_hdr->report_length = cpu_to_be16(size);
        oops_hdr->timestamp = cpu_to_be64(get_seconds());

        if (compressed)
                err_type = ERR_TYPE_KERNEL_PANIC_GZ;

        rc = nvram_write_os_partition(&oops_log_partition, oops_buf,
                (int) (sizeof(*oops_hdr) + size), err_type, count);

        if (rc != 0)
                return rc;

        *id = part;
        return 0;
}

/*
 * Reads the oops/panic report, rtas, of-config and common partition.
 * Returns the length of the data we read from each partition.
 * Returns 0 if we've been called before.
 */
static ssize_t nvram_pstore_read(u64 *id, enum pstore_type_id *type,
                                int *count, struct timespec *time, char **buf,
                                bool *compressed, struct pstore_info *psi)
{
        struct oops_log_info *oops_hdr;
        unsigned int err_type, id_no, size = 0;
        struct nvram_os_partition *part = NULL;
        char *buff = NULL;
        int sig = 0;
        loff_t p;

        read_type++;

        switch (nvram_type_ids[read_type]) {
        case PSTORE_TYPE_DMESG:
                part = &oops_log_partition;
                *type = PSTORE_TYPE_DMESG;
                break;
        case PSTORE_TYPE_PPC_RTAS:
                part = &rtas_log_partition;
                *type = PSTORE_TYPE_PPC_RTAS;
                time->tv_sec = last_rtas_event;
                time->tv_nsec = 0;
                break;
        case PSTORE_TYPE_PPC_OF:
                sig = NVRAM_SIG_OF;
                part = &of_config_partition;
                *type = PSTORE_TYPE_PPC_OF;
                *id = PSTORE_TYPE_PPC_OF;
                time->tv_sec = 0;
                time->tv_nsec = 0;
                break;
        case PSTORE_TYPE_PPC_COMMON:
                sig = NVRAM_SIG_SYS;
                part = &common_partition;
                *type = PSTORE_TYPE_PPC_COMMON;
                *id = PSTORE_TYPE_PPC_COMMON;
                time->tv_sec = 0;
                time->tv_nsec = 0;
                break;
        default:
                return 0;
        }

        if (!part->os_partition) {
                p = nvram_find_partition(part->name, sig, &size);
                if (p <= 0) {
                        pr_err("nvram: Failed to find partition %s, "
                                "err %d\n", part->name, (int)p);
                        return 0;
                }
                part->index = p;
                part->size = size;
        }

        buff = kmalloc(part->size, GFP_KERNEL);

        if (!buff)
                return -ENOMEM;

        if (nvram_read_partition(part, buff, part->size, &err_type, &id_no)) {
                kfree(buff);
                return 0;
        }

        *count = 0;

        if (part->os_partition)
                *id = id_no;

        if (nvram_type_ids[read_type] == PSTORE_TYPE_DMESG) {
                size_t length, hdr_size;

                oops_hdr = (struct oops_log_info *)buff;
                if (be16_to_cpu(oops_hdr->version) < OOPS_HDR_VERSION) {
                        /* Old format oops header had 2-byte record size */
                        hdr_size = sizeof(u16);
                        length = be16_to_cpu(oops_hdr->version);
                        time->tv_sec = 0;
                        time->tv_nsec = 0;
                } else {
                        hdr_size = sizeof(*oops_hdr);
                        length = be16_to_cpu(oops_hdr->report_length);
                        time->tv_sec = be64_to_cpu(oops_hdr->timestamp);
                        time->tv_nsec = 0;
                }
                *buf = kmalloc(length, GFP_KERNEL);
                if (*buf == NULL)
                        return -ENOMEM;
                memcpy(*buf, buff + hdr_size, length);
                kfree(buff);

                if (err_type == ERR_TYPE_KERNEL_PANIC_GZ)
                        *compressed = true;
                else
                        *compressed = false;
                return length;
        }

        *buf = buff;
        return part->size;
}

static struct pstore_info nvram_pstore_info = {
        .owner = THIS_MODULE,
        .name = "nvram",
        .open = nvram_pstore_open,
        .read = nvram_pstore_read,
        .write = nvram_pstore_write,
};

static int nvram_pstore_init(void)
{
        int rc = 0;

        nvram_pstore_info.buf = oops_data;
        nvram_pstore_info.bufsize = oops_data_sz;

        rc = pstore_register(&nvram_pstore_info);
        if (rc != 0)
                pr_err("nvram: pstore_register() failed, defaults to "
                                "kmsg_dump; returned %d\n", rc);

        return rc;
}
#else
static int nvram_pstore_init(void)
{
        return -1;
}
#endif

static void __init nvram_init_oops_partition(int rtas_partition_exists)
{
        int rc;

        rc = pseries_nvram_init_os_partition(&oops_log_partition);
        if (rc != 0) {
                if (!rtas_partition_exists)
                        return;
                pr_notice("nvram: Using %s partition to log both"
                        " RTAS errors and oops/panic reports\n",
                        rtas_log_partition.name);
                memcpy(&oops_log_partition, &rtas_log_partition,
                                                sizeof(rtas_log_partition));
        }
        oops_buf = kmalloc(oops_log_partition.size, GFP_KERNEL);
        if (!oops_buf) {
                pr_err("nvram: No memory for %s partition\n",
                                                oops_log_partition.name);
                return;
        }
        oops_data = oops_buf + sizeof(struct oops_log_info);
        oops_data_sz = oops_log_partition.size - sizeof(struct oops_log_info);

        rc = nvram_pstore_init();

        if (!rc)
                return;

        /*
         * Figure compression (preceded by elimination of each line's <n>
         * severity prefix) will reduce the oops/panic report to at most
         * 45% of its original size.
         */
        big_oops_buf_sz = (oops_data_sz * 100) / 45;
        big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
        if (big_oops_buf) {
                stream.workspace =  kmalloc(zlib_deflate_workspacesize(
                                        WINDOW_BITS, MEM_LEVEL), GFP_KERNEL);
                if (!stream.workspace) {
                        pr_err("nvram: No memory for compression workspace; "
                                "skipping compression of %s partition data\n",
                                oops_log_partition.name);
                        kfree(big_oops_buf);
                        big_oops_buf = NULL;
                }
        } else {
                pr_err("No memory for uncompressed %s data; "
                        "skipping compression\n", oops_log_partition.name);
                stream.workspace = NULL;
        }

        rc = kmsg_dump_register(&nvram_kmsg_dumper);
        if (rc != 0) {
                pr_err("nvram: kmsg_dump_register() failed; returned %d\n", rc);
                kfree(oops_buf);
                kfree(big_oops_buf);
                kfree(stream.workspace);
        }
}

static int __init pseries_nvram_init_log_partitions(void)
{
        int rc;

        /* Scan nvram for partitions */
        nvram_scan_partitions();

        rc = pseries_nvram_init_os_partition(&rtas_log_partition);
        nvram_init_oops_partition(rc == 0);
        return 0;
}
machine_arch_initcall(pseries, pseries_nvram_init_log_partitions);

int __init pSeries_nvram_init(void)
{
        struct device_node *nvram;
        const __be32 *nbytes_p;
        unsigned int proplen;

        nvram = of_find_node_by_type(NULL, "nvram");
        if (nvram == NULL)
                return -ENODEV;

        nbytes_p = of_get_property(nvram, "#bytes", &proplen);
        if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
                of_node_put(nvram);
                return -EIO;
        }

        nvram_size = be32_to_cpup(nbytes_p);

        nvram_fetch = rtas_token("nvram-fetch");
        nvram_store = rtas_token("nvram-store");
        printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
        of_node_put(nvram);

        ppc_md.nvram_read       = pSeries_nvram_read;
        ppc_md.nvram_write      = pSeries_nvram_write;
        ppc_md.nvram_size       = pSeries_nvram_get_size;

        return 0;
}


/*
 * This is our kmsg_dump callback, called after an oops or panic report
 * has been written to the printk buffer.  We want to capture as much
 * of the printk buffer as possible.  First, capture as much as we can
 * that we think will compress sufficiently to fit in the lnx,oops-log
 * partition.  If that's too much, go back and capture uncompressed text.
 */
static void oops_to_nvram(struct kmsg_dumper *dumper,
                          enum kmsg_dump_reason reason)
{
        struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
        static unsigned int oops_count = 0;
        static bool panicking = false;
        static DEFINE_SPINLOCK(lock);
        unsigned long flags;
        size_t text_len;
        unsigned int err_type = ERR_TYPE_KERNEL_PANIC_GZ;
        int rc = -1;

        switch (reason) {
        case KMSG_DUMP_RESTART:
        case KMSG_DUMP_HALT:
        case KMSG_DUMP_POWEROFF:
                /* These are almost always orderly shutdowns. */
                return;
        case KMSG_DUMP_OOPS:
                break;
        case KMSG_DUMP_PANIC:
                panicking = true;
                break;
        case KMSG_DUMP_EMERG:
                if (panicking)
                        /* Panic report already captured. */
                        return;
                break;
        default:
                pr_err("%s: ignoring unrecognized KMSG_DUMP_* reason %d\n",
                                                __FUNCTION__, (int) reason);
                return;
        }

        if (clobbering_unread_rtas_event())
                return;

        if (!spin_trylock_irqsave(&lock, flags))
                return;

        if (big_oops_buf) {
                kmsg_dump_get_buffer(dumper, false,
                                     big_oops_buf, big_oops_buf_sz, &text_len);
                rc = zip_oops(text_len);
        }
        if (rc != 0) {
                kmsg_dump_rewind(dumper);
                kmsg_dump_get_buffer(dumper, false,
                                     oops_data, oops_data_sz, &text_len);
                err_type = ERR_TYPE_KERNEL_PANIC;
                oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION);
                oops_hdr->report_length = cpu_to_be16(text_len);
                oops_hdr->timestamp = cpu_to_be64(get_seconds());
        }

        (void) nvram_write_os_partition(&oops_log_partition, oops_buf,
                (int) (sizeof(*oops_hdr) + text_len), err_type,
                ++oops_count);

        spin_unlock_irqrestore(&lock, flags);
}