/*
 *  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
 *
 * TODO: Split the /dev/nvram part (that one can use
 *       drivers/char/generic_nvram.c) from the arch & partition
 *       parsing code.
 */

#include <linux/module.h>

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/nvram.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <asm/uaccess.h>
#include <asm/nvram.h>
#include <asm/rtas.h>
#include <asm/prom.h>
#include <asm/machdep.h>

#undef DEBUG_NVRAM

static struct nvram_partition * nvram_part;
static long nvram_error_log_index = -1;
static long nvram_error_log_size = 0;

struct err_log_info {
        int error_type;
        unsigned int seq_num;
};

static loff_t dev_nvram_llseek(struct file *file, loff_t offset, int origin)
{
        int size;

        if (ppc_md.nvram_size == NULL)
                return -ENODEV;
        size = ppc_md.nvram_size();

        switch (origin) {
        case 1:
                offset += file->f_pos;
                break;
        case 2:
                offset += size;
                break;
        }
        if (offset < 0)
                return -EINVAL;
        file->f_pos = offset;
        return file->f_pos;
}


static ssize_t dev_nvram_read(struct file *file, char __user *buf,
                          size_t count, loff_t *ppos)
{
        ssize_t ret;
        char *tmp = NULL;
        ssize_t size;

        ret = -ENODEV;
        if (!ppc_md.nvram_size)
                goto out;

        ret = 0;
        size = ppc_md.nvram_size();
        if (*ppos >= size || size < 0)
                goto out;

        count = min_t(size_t, count, size - *ppos);
        count = min(count, PAGE_SIZE);

        ret = -ENOMEM;
        tmp = kmalloc(count, GFP_KERNEL);
        if (!tmp)
                goto out;

        ret = ppc_md.nvram_read(tmp, count, ppos);
        if (ret <= 0)
                goto out;

        if (copy_to_user(buf, tmp, ret))
                ret = -EFAULT;

out:
        kfree(tmp);
        return ret;

}

static ssize_t dev_nvram_write(struct file *file, const char __user *buf,
                          size_t count, loff_t *ppos)
{
        ssize_t ret;
        char *tmp = NULL;
        ssize_t size;

        ret = -ENODEV;
        if (!ppc_md.nvram_size)
                goto out;

        ret = 0;
        size = ppc_md.nvram_size();
        if (*ppos >= size || size < 0)
                goto out;

        count = min_t(size_t, count, size - *ppos);
        count = min(count, PAGE_SIZE);

        ret = -ENOMEM;
        tmp = kmalloc(count, GFP_KERNEL);
        if (!tmp)
                goto out;

        ret = -EFAULT;
        if (copy_from_user(tmp, buf, count))
                goto out;

        ret = ppc_md.nvram_write(tmp, count, ppos);

out:
        kfree(tmp);
        return ret;

}

static int dev_nvram_ioctl(struct inode *inode, struct file *file,
        unsigned int cmd, unsigned long arg)
{
        switch(cmd) {
#ifdef CONFIG_PPC_PMAC
        case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
                printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
        case IOC_NVRAM_GET_OFFSET: {
                int part, offset;

                if (!machine_is(powermac))
                        return -EINVAL;
                if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
                        return -EFAULT;
                if (part < pmac_nvram_OF || part > pmac_nvram_NR)
                        return -EINVAL;
                offset = pmac_get_partition(part);
                if (offset < 0)
                        return offset;
                if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
                        return -EFAULT;
                return 0;
        }
#endif /* CONFIG_PPC_PMAC */
        default:
                return -EINVAL;
        }
}

const struct file_operations nvram_fops = {
        .owner =        THIS_MODULE,
        .llseek =       dev_nvram_llseek,
        .read =         dev_nvram_read,
        .write =        dev_nvram_write,
        .ioctl =        dev_nvram_ioctl,
};

static struct miscdevice nvram_dev = {
        NVRAM_MINOR,
        "nvram",
        &nvram_fops
};


#ifdef DEBUG_NVRAM
static void nvram_print_partitions(char * label)
{
        struct list_head * p;
        struct nvram_partition * tmp_part;
        
        printk(KERN_WARNING "--------%s---------\n", label);
        printk(KERN_WARNING "indx\t\tsig\tchks\tlen\tname\n");
        list_for_each(p, &nvram_part->partition) {
                tmp_part = list_entry(p, struct nvram_partition, partition);
                printk(KERN_WARNING "%4d    \t%02x\t%02x\t%d\t%s\n",
                       tmp_part->index, tmp_part->header.signature,
                       tmp_part->header.checksum, tmp_part->header.length,
                       tmp_part->header.name);
        }
}
#endif


static int nvram_write_header(struct nvram_partition * part)
{
        loff_t tmp_index;
        int rc;
        
        tmp_index = part->index;
        rc = ppc_md.nvram_write((char *)&part->header, NVRAM_HEADER_LEN, &tmp_index); 

        return rc;
}


static unsigned char nvram_checksum(struct nvram_header *p)
{
        unsigned int c_sum, c_sum2;
        unsigned short *sp = (unsigned short *)p->name; /* assume 6 shorts */
        c_sum = p->signature + p->length + sp[0] + sp[1] + sp[2] + sp[3] + sp[4] + sp[5];

        /* The sum may have spilled into the 3rd byte.  Fold it back. */
        c_sum = ((c_sum & 0xffff) + (c_sum >> 16)) & 0xffff;
        /* The sum cannot exceed 2 bytes.  Fold it into a checksum */
        c_sum2 = (c_sum >> 8) + (c_sum << 8);
        c_sum = ((c_sum + c_sum2) >> 8) & 0xff;
        return c_sum;
}


/*
 * Find an nvram partition, sig can be 0 for any
 * partition or name can be NULL for any name, else
 * tries to match both
 */
struct nvram_partition *nvram_find_partition(int sig, const char *name)
{
        struct nvram_partition * part;
        struct list_head * p;

        list_for_each(p, &nvram_part->partition) {
                part = list_entry(p, struct nvram_partition, partition);

                if (sig && part->header.signature != sig)
                        continue;
                if (name && 0 != strncmp(name, part->header.name, 12))
                        continue;
                return part; 
        }
        return NULL;
}
EXPORT_SYMBOL(nvram_find_partition);


static int nvram_remove_os_partition(void)
{
        struct list_head *i;
        struct list_head *j;
        struct nvram_partition * part;
        struct nvram_partition * cur_part;
        int rc;

        list_for_each(i, &nvram_part->partition) {
                part = list_entry(i, struct nvram_partition, partition);
                if (part->header.signature != NVRAM_SIG_OS)
                        continue;
                
                /* Make os partition a free partition */
                part->header.signature = NVRAM_SIG_FREE;
                sprintf(part->header.name, "wwwwwwwwwwww");
                part->header.checksum = nvram_checksum(&part->header);

                /* Merge contiguous free partitions backwards */
                list_for_each_prev(j, &part->partition) {
                        cur_part = list_entry(j, struct nvram_partition, partition);
                        if (cur_part == nvram_part || cur_part->header.signature != NVRAM_SIG_FREE) {
                                break;
                        }
                        
                        part->header.length += cur_part->header.length;
                        part->header.checksum = nvram_checksum(&part->header);
                        part->index = cur_part->index;

                        list_del(&cur_part->partition);
                        kfree(cur_part);
                        j = &part->partition; /* fixup our loop */
                }
                
                /* Merge contiguous free partitions forwards */
                list_for_each(j, &part->partition) {
                        cur_part = list_entry(j, struct nvram_partition, partition);
                        if (cur_part == nvram_part || cur_part->header.signature != NVRAM_SIG_FREE) {
                                break;
                        }

                        part->header.length += cur_part->header.length;
                        part->header.checksum = nvram_checksum(&part->header);

                        list_del(&cur_part->partition);
                        kfree(cur_part);
                        j = &part->partition; /* fixup our loop */
                }
                
                rc = nvram_write_header(part);
                if (rc <= 0) {
                        printk(KERN_ERR "nvram_remove_os_partition: nvram_write failed (%d)\n", rc);
                        return rc;
                }

        }
        
        return 0;
}

/* nvram_create_os_partition
 *
 * Create a OS linux partition to buffer error logs.
 * Will create a partition starting at the first free
 * space found if space has enough room.
 */
static int nvram_create_os_partition(void)
{
        struct nvram_partition *part;
        struct nvram_partition *new_part;
        struct nvram_partition *free_part = NULL;
        int seq_init[2] = { 0, 0 };
        loff_t tmp_index;
        long size = 0;
        int rc;
        
        /* Find a free partition that will give us the maximum needed size 
           If can't find one that will give us the minimum size needed */
        list_for_each_entry(part, &nvram_part->partition, partition) {
                if (part->header.signature != NVRAM_SIG_FREE)
                        continue;

                if (part->header.length >= NVRAM_MAX_REQ) {
                        size = NVRAM_MAX_REQ;
                        free_part = part;
                        break;
                }
                if (!size && part->header.length >= NVRAM_MIN_REQ) {
                        size = NVRAM_MIN_REQ;
                        free_part = part;
                }
        }
        if (!size)
                return -ENOSPC;
        
        /* Create our OS partition */
        new_part = kmalloc(sizeof(*new_part), GFP_KERNEL);
        if (!new_part) {
                printk(KERN_ERR "nvram_create_os_partition: kmalloc failed\n");
                return -ENOMEM;
        }

        new_part->index = free_part->index;
        new_part->header.signature = NVRAM_SIG_OS;
        new_part->header.length = size;
        strcpy(new_part->header.name, "ppc64,linux");
        new_part->header.checksum = nvram_checksum(&new_part->header);

        rc = nvram_write_header(new_part);
        if (rc <= 0) {
                printk(KERN_ERR "nvram_create_os_partition: nvram_write_header \
                                failed (%d)\n", rc);
                return rc;
        }

        /* make sure and initialize to zero the sequence number and the error
           type logged */
        tmp_index = new_part->index + NVRAM_HEADER_LEN;
        rc = ppc_md.nvram_write((char *)&seq_init, sizeof(seq_init), &tmp_index);
        if (rc <= 0) {
                printk(KERN_ERR "nvram_create_os_partition: nvram_write "
                                "failed (%d)\n", rc);
                return rc;
        }
        
        nvram_error_log_index = new_part->index + NVRAM_HEADER_LEN;
        nvram_error_log_size = ((part->header.length - 1) *
                                NVRAM_BLOCK_LEN) - sizeof(struct err_log_info);
        
        list_add_tail(&new_part->partition, &free_part->partition);

        if (free_part->header.length <= size) {
                list_del(&free_part->partition);
                kfree(free_part);
                return 0;
        } 

        /* Adjust the partition we stole the space from */
        free_part->index += size * NVRAM_BLOCK_LEN;
        free_part->header.length -= size;
        free_part->header.checksum = nvram_checksum(&free_part->header);
        
        rc = nvram_write_header(free_part);
        if (rc <= 0) {
                printk(KERN_ERR "nvram_create_os_partition: nvram_write_header "
                       "failed (%d)\n", rc);
                return rc;
        }

        return 0;
}


/* nvram_setup_partition
 *
 * This will setup the partition we need for buffering the
 * error logs and cleanup partitions if needed.
 *
 * The general strategy is the following:
 * 1.) If there is ppc64,linux partition large enough then use it.
 * 2.) If there is not a ppc64,linux partition large enough, search
 * for a free partition that is large enough.
 * 3.) If there is not a free partition large enough remove 
 * _all_ OS partitions and consolidate the space.
 * 4.) Will first try getting a chunk that will satisfy the maximum
 * error log size (NVRAM_MAX_REQ).
 * 5.) If the max chunk cannot be allocated then try finding a chunk
 * that will satisfy the minum needed (NVRAM_MIN_REQ).
 */
static int nvram_setup_partition(void)
{
        struct list_head * p;
        struct nvram_partition * part;
        int rc;

        /* For now, we don't do any of this on pmac, until I
         * have figured out if it's worth killing some unused stuffs
         * in our nvram, as Apple defined partitions use pretty much
         * all of the space
         */
        if (machine_is(powermac))
                return -ENOSPC;

        /* see if we have an OS partition that meets our needs.
           will try getting the max we need.  If not we'll delete
           partitions and try again. */
        list_for_each(p, &nvram_part->partition) {
                part = list_entry(p, struct nvram_partition, partition);
                if (part->header.signature != NVRAM_SIG_OS)
                        continue;

                if (strcmp(part->header.name, "ppc64,linux"))
                        continue;

                if (part->header.length >= NVRAM_MIN_REQ) {
                        /* found our partition */
                        nvram_error_log_index = part->index + NVRAM_HEADER_LEN;
                        nvram_error_log_size = ((part->header.length - 1) *
                                                NVRAM_BLOCK_LEN) - sizeof(struct err_log_info);
                        return 0;
                }
        }
        
        /* try creating a partition with the free space we have */
        rc = nvram_create_os_partition();
        if (!rc) {
                return 0;
        }
                
        /* need to free up some space */
        rc = nvram_remove_os_partition();
        if (rc) {
                return rc;
        }
        
        /* create a partition in this new space */
        rc = nvram_create_os_partition();
        if (rc) {
                printk(KERN_ERR "nvram_create_os_partition: Could not find a "
                       "NVRAM partition large enough\n");
                return rc;
        }
        
        return 0;
}


static int nvram_scan_partitions(void)
{
        loff_t cur_index = 0;
        struct nvram_header phead;
        struct nvram_partition * tmp_part;
        unsigned char c_sum;
        char * header;
        int total_size;
        int err;

        if (ppc_md.nvram_size == NULL)
                return -ENODEV;
        total_size = ppc_md.nvram_size();
        
        header = kmalloc(NVRAM_HEADER_LEN, GFP_KERNEL);
        if (!header) {
                printk(KERN_ERR "nvram_scan_partitions: Failed kmalloc\n");
                return -ENOMEM;
        }

        while (cur_index < total_size) {

                err = ppc_md.nvram_read(header, NVRAM_HEADER_LEN, &cur_index);
                if (err != NVRAM_HEADER_LEN) {
                        printk(KERN_ERR "nvram_scan_partitions: Error parsing "
                               "nvram partitions\n");
                        goto out;
                }

                cur_index -= NVRAM_HEADER_LEN; /* nvram_read will advance us */

                memcpy(&phead, header, NVRAM_HEADER_LEN);

                err = 0;
                c_sum = nvram_checksum(&phead);
                if (c_sum != phead.checksum) {
                        printk(KERN_WARNING "WARNING: nvram partition checksum"
                               " was %02x, should be %02x!\n",
                               phead.checksum, c_sum);
                        printk(KERN_WARNING "Terminating nvram partition scan\n");
                        goto out;
                }
                if (!phead.length) {
                        printk(KERN_WARNING "WARNING: nvram corruption "
                               "detected: 0-length partition\n");
                        goto out;
                }
                tmp_part = (struct nvram_partition *)
                        kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
                err = -ENOMEM;
                if (!tmp_part) {
                        printk(KERN_ERR "nvram_scan_partitions: kmalloc failed\n");
                        goto out;
                }
                
                memcpy(&tmp_part->header, &phead, NVRAM_HEADER_LEN);
                tmp_part->index = cur_index;
                list_add_tail(&tmp_part->partition, &nvram_part->partition);
                
                cur_index += phead.length * NVRAM_BLOCK_LEN;
        }
        err = 0;

 out:
        kfree(header);
        return err;
}

static int __init nvram_init(void)
{
        int error;
        int rc;
        
        if (ppc_md.nvram_size == NULL || ppc_md.nvram_size() <= 0)
                return  -ENODEV;

        rc = misc_register(&nvram_dev);
        if (rc != 0) {
                printk(KERN_ERR "nvram_init: failed to register device\n");
                return rc;
        }
        
        /* initialize our anchor for the nvram partition list */
        nvram_part = kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
        if (!nvram_part) {
                printk(KERN_ERR "nvram_init: Failed kmalloc\n");
                return -ENOMEM;
        }
        INIT_LIST_HEAD(&nvram_part->partition);
  
        /* Get all the NVRAM partitions */
        error = nvram_scan_partitions();
        if (error) {
                printk(KERN_ERR "nvram_init: Failed nvram_scan_partitions\n");
                return error;
        }
                
        if(nvram_setup_partition()) 
                printk(KERN_WARNING "nvram_init: Could not find nvram partition"
                       " for nvram buffered error logging.\n");
  
#ifdef DEBUG_NVRAM
        nvram_print_partitions("NVRAM Partitions");
#endif

        return rc;
}

void __exit nvram_cleanup(void)
{
        misc_deregister( &nvram_dev );
}


#ifdef CONFIG_PPC_PSERIES

/* 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            nvram_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_error_log(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 (nvram_error_log_index == -1) {
                return -ESPIPE;
        }

        if (length > nvram_error_log_size) {
                length = nvram_error_log_size;
        }

        info.error_type = err_type;
        info.seq_num = error_log_cnt;

        tmp_index = nvram_error_log_index;

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

        rc = ppc_md.nvram_write(buff, length, &tmp_index);
        if (rc <= 0) {
                printk(KERN_ERR "nvram_write_error_log: Failed nvram_write (%d)\n", rc);
                return rc;
        }
        
        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)
{
        int rc;
        loff_t tmp_index;
        struct err_log_info info;
        
        if (nvram_error_log_index == -1)
                return -1;

        if (length > nvram_error_log_size)
                length = nvram_error_log_size;

        tmp_index = nvram_error_log_index;

        rc = ppc_md.nvram_read((char *)&info, sizeof(struct err_log_info), &tmp_index);
        if (rc <= 0) {
                printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
                return rc;
        }

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

        *error_log_cnt = info.seq_num;
        *err_type = info.error_type;

        return 0;
}

/* 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;

        tmp_index = nvram_error_log_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;
        }

        return 0;
}

#endif /* CONFIG_PPC_PSERIES */

module_init(nvram_init);
module_exit(nvram_cleanup);
MODULE_LICENSE("GPL");