/*
 *  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");