/*
 *  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

#define NVRAM_HEADER_LEN        sizeof(struct nvram_header)
#define NVRAM_BLOCK_LEN         NVRAM_HEADER_LEN

/* If change this size, then change the size of NVNAME_LEN */
struct nvram_header {
        unsigned char signature;
        unsigned char checksum;
        unsigned short length;
        /* Terminating null required only for names < 12 chars. */
        char name[12];
};

struct nvram_partition {
        struct list_head partition;
        struct nvram_header header;
        unsigned int index;
};

static LIST_HEAD(nvram_partitions);

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;

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

        size = ppc_md.nvram_size();
        if (size < 0) {
                ret = size;
                goto out;
        }

        if (*ppos >= size) {
                ret = 0;
                goto out;
        }

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

        tmp = kmalloc(count, GFP_KERNEL);
        if (!tmp) {
                ret = -ENOMEM;
                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 long dev_nvram_ioctl(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,
        .unlocked_ioctl = dev_nvram_ioctl,
};

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


#ifdef DEBUG_NVRAM
static void __init nvram_print_partitions(char * label)
{
        struct nvram_partition * tmp_part;
        
        printk(KERN_WARNING "--------%s---------\n", label);
        printk(KERN_WARNING "indx\t\tsig\tchks\tlen\tname\n");
        list_for_each_entry(tmp_part, &nvram_partitions, partition) {
                printk(KERN_WARNING "%4d    \t%02x\t%02x\t%d\t%12.12s\n",
                       tmp_part->index, tmp_part->header.signature,
                       tmp_part->header.checksum, tmp_part->header.length,
                       tmp_part->header.name);
        }
}
#endif


static int __init nvram_write_header(struct nvram_partition * part)
{
        loff_t tmp_index;
        int rc;
        struct nvram_header phead;

        memcpy(&phead, &part->header, NVRAM_HEADER_LEN);
        phead.length = cpu_to_be16(phead.length);

        tmp_index = part->index;
        rc = ppc_md.nvram_write((char *)&phead, NVRAM_HEADER_LEN, &tmp_index);

        return rc;
}


static unsigned char __init 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;
}

/*
 * Per the criteria passed via nvram_remove_partition(), should this
 * partition be removed?  1=remove, 0=keep
 */
static int nvram_can_remove_partition(struct nvram_partition *part,
                const char *name, int sig, const char *exceptions[])
{
        if (part->header.signature != sig)
                return 0;
        if (name) {
                if (strncmp(name, part->header.name, 12))
                        return 0;
        } else if (exceptions) {
                const char **except;
                for (except = exceptions; *except; except++) {
                        if (!strncmp(*except, part->header.name, 12))
                                return 0;
                }
        }
        return 1;
}

/**
 * nvram_remove_partition - Remove one or more partitions in nvram
 * @name: name of the partition to remove, or NULL for a
 *        signature only match
 * @sig: signature of the partition(s) to remove
 * @exceptions: When removing all partitions with a matching signature,
 *        leave these alone.
 */

int __init nvram_remove_partition(const char *name, int sig,
                                                const char *exceptions[])
{
        struct nvram_partition *part, *prev, *tmp;
        int rc;

        list_for_each_entry(part, &nvram_partitions, partition) {
                if (!nvram_can_remove_partition(part, name, sig, exceptions))
                        continue;

                /* Make partition a free partition */
                part->header.signature = NVRAM_SIG_FREE;
                strncpy(part->header.name, "wwwwwwwwwwww", 12);
                part->header.checksum = nvram_checksum(&part->header);
                rc = nvram_write_header(part);
                if (rc <= 0) {
                        printk(KERN_ERR "nvram_remove_partition: nvram_write failed (%d)\n", rc);
                        return rc;
                }
        }

        /* Merge contiguous ones */
        prev = NULL;
        list_for_each_entry_safe(part, tmp, &nvram_partitions, partition) {
                if (part->header.signature != NVRAM_SIG_FREE) {
                        prev = NULL;
                        continue;
                }
                if (prev) {
                        prev->header.length += part->header.length;
                        prev->header.checksum = nvram_checksum(&part->header);
                        rc = nvram_write_header(part);
                        if (rc <= 0) {
                                printk(KERN_ERR "nvram_remove_partition: nvram_write failed (%d)\n", rc);
                                return rc;
                        }
                        list_del(&part->partition);
                        kfree(part);
                } else
                        prev = part;
        }
        
        return 0;
}

/**
 * nvram_create_partition - Create a partition in nvram
 * @name: name of the partition to create
 * @sig: signature of the partition to create
 * @req_size: size of data to allocate in bytes
 * @min_size: minimum acceptable size (0 means req_size)
 *
 * Returns a negative error code or a positive nvram index
 * of the beginning of the data area of the newly created
 * partition. If you provided a min_size smaller than req_size
 * you need to query for the actual size yourself after the
 * call using nvram_partition_get_size().
 */
loff_t __init nvram_create_partition(const char *name, int sig,
                                     int req_size, int min_size)
{
        struct nvram_partition *part;
        struct nvram_partition *new_part;
        struct nvram_partition *free_part = NULL;
        static char nv_init_vals[16];
        loff_t tmp_index;
        long size = 0;
        int rc;

        /* Convert sizes from bytes to blocks */
        req_size = _ALIGN_UP(req_size, NVRAM_BLOCK_LEN) / NVRAM_BLOCK_LEN;
        min_size = _ALIGN_UP(min_size, NVRAM_BLOCK_LEN) / NVRAM_BLOCK_LEN;

        /* If no minimum size specified, make it the same as the
         * requested size
         */
        if (min_size == 0)
                min_size = req_size;
        if (min_size > req_size)
                return -EINVAL;

        /* Now add one block to each for the header */
        req_size += 1;
        min_size += 1;

        /* 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_partitions, partition) {
                if (part->header.signature != NVRAM_SIG_FREE)
                        continue;

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

        new_part->index = free_part->index;
        new_part->header.signature = sig;
        new_part->header.length = size;
        strncpy(new_part->header.name, name, 12);
        new_part->header.checksum = nvram_checksum(&new_part->header);

        rc = nvram_write_header(new_part);
        if (rc <= 0) {
                pr_err("nvram_create_os_partition: nvram_write_header "
                       "failed (%d)\n", rc);
                return rc;
        }
        list_add_tail(&new_part->partition, &free_part->partition);

        /* Adjust or remove the partition we stole the space from */
        if (free_part->header.length > size) {
                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) {
                        pr_err("nvram_create_os_partition: nvram_write_header "
                               "failed (%d)\n", rc);
                        return rc;
                }
        } else {
                list_del(&free_part->partition);
                kfree(free_part);
        } 

        /* Clear the new partition */
        for (tmp_index = new_part->index + NVRAM_HEADER_LEN;
             tmp_index <  ((size - 1) * NVRAM_BLOCK_LEN);
             tmp_index += NVRAM_BLOCK_LEN) {
                rc = ppc_md.nvram_write(nv_init_vals, NVRAM_BLOCK_LEN, &tmp_index);
                if (rc <= 0) {
                        pr_err("nvram_create_partition: nvram_write failed (%d)\n", rc);
                        return rc;
                }
        }
        
        return new_part->index + NVRAM_HEADER_LEN;
}

/**
 * nvram_get_partition_size - Get the data size of an nvram partition
 * @data_index: This is the offset of the start of the data of
 *              the partition. The same value that is returned by
 *              nvram_create_partition().
 */
int nvram_get_partition_size(loff_t data_index)
{
        struct nvram_partition *part;
        
        list_for_each_entry(part, &nvram_partitions, partition) {
                if (part->index + NVRAM_HEADER_LEN == data_index)
                        return (part->header.length - 1) * NVRAM_BLOCK_LEN;
        }
        return -1;
}


/**
 * nvram_find_partition - Find an nvram partition by signature and name
 * @name: Name of the partition or NULL for any name
 * @sig: Signature to test against
 * @out_size: if non-NULL, returns the size of the data part of the partition
 */
loff_t nvram_find_partition(const char *name, int sig, int *out_size)
{
        struct nvram_partition *p;

        list_for_each_entry(p, &nvram_partitions, partition) {
                if (p->header.signature == sig &&
                    (!name || !strncmp(p->header.name, name, 12))) {
                        if (out_size)
                                *out_size = (p->header.length - 1) *
                                        NVRAM_BLOCK_LEN;
                        return p->index + NVRAM_HEADER_LEN;
                }
        }
        return 0;
}

int __init 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 || ppc_md.nvram_size() <= 0)
                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);

                phead.length = be16_to_cpu(phead.length);

                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 = 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_partitions);
                
                cur_index += phead.length * NVRAM_BLOCK_LEN;
        }
        err = 0;

#ifdef DEBUG_NVRAM
        nvram_print_partitions("NVRAM Partitions");
#endif

 out:
        kfree(header);
        return err;
}

static int __init nvram_init(void)
{
        int rc;
        
        BUILD_BUG_ON(NVRAM_BLOCK_LEN != 16);

        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;
        }
        
        return rc;
}

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

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