/* Copyright (c) 2012, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/jiffies.h>
#include <linux/debugfs.h>
#include <linux/io.h>
#include <linux/idr.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/completion.h>

#include <mach/msm_ipc_logging.h>

#include "ipc_logging.h"

static DEFINE_MUTEX(ipc_log_debugfs_init_lock);
static struct dentry *root_dent;
#define MAX_MSG_DECODED_SIZE (MAX_MSG_SIZE*4)

static void *get_deserialization_func(struct ipc_log_context *ilctxt,
				      int type)
{
	struct dfunc_info *df_info = NULL;

	if (!ilctxt)
		return NULL;

	list_for_each_entry(df_info, &ilctxt->dfunc_info_list, list) {
		if (df_info->type == type)
			return df_info->dfunc;
	}
	return NULL;
}

static int deserialize_log(struct ipc_log_context *ilctxt,
			   char *buff, int size)
{
	struct encode_context ectxt;
	struct decode_context dctxt;
	void (*deserialize_func)(struct encode_context *ectxt,
				 struct decode_context *dctxt);
	unsigned long flags;

	dctxt.output_format = OUTPUT_DEBUGFS;
	dctxt.buff = buff;
	dctxt.size = size;
	spin_lock_irqsave(&ipc_log_context_list_lock, flags);
	spin_lock(&ilctxt->ipc_log_context_lock);
	while (dctxt.size >= MAX_MSG_DECODED_SIZE &&
	       !is_ilctxt_empty(ilctxt)) {
		msg_read(ilctxt, &ectxt);
		deserialize_func = get_deserialization_func(ilctxt,
							ectxt.hdr.type);
		spin_unlock(&ilctxt->ipc_log_context_lock);
		spin_unlock_irqrestore(&ipc_log_context_list_lock, flags);
		if (deserialize_func)
			deserialize_func(&ectxt, &dctxt);
		else
			pr_err("%s: unknown message 0x%x\n",
				__func__, ectxt.hdr.type);
		spin_lock_irqsave(&ipc_log_context_list_lock, flags);
		spin_lock(&ilctxt->ipc_log_context_lock);
	}
	if ((size - dctxt.size) == 0)
		init_completion(&ilctxt->read_avail);
	spin_unlock(&ilctxt->ipc_log_context_lock);
	spin_unlock_irqrestore(&ipc_log_context_list_lock, flags);
	return size - dctxt.size;
}

static int debug_log(struct ipc_log_context *ilctxt,
		     char *buff, int size, int cont)
{
	int i = 0;

	if (size < MAX_MSG_DECODED_SIZE) {
		pr_err("%s: buffer size %d < %d\n", __func__, size,
			MAX_MSG_DECODED_SIZE);
		return -ENOMEM;
	}
	do {
		i = deserialize_log(ilctxt, buff, size - 1);
		if (cont && i == 0) {
			wait_for_completion_interruptible(&ilctxt->read_avail);
			if (signal_pending(current))
				break;
		}
	} while (cont && i == 0);

	return i;
}

/*
 * VFS Read operation helper which dispatches the call to the debugfs
 * read command stored in file->private_data.
 *
 * @file  File structure
 * @buff   user buffer
 * @count size of user buffer
 * @ppos  file position to read from (only a value of 0 is accepted)
 * @cont  1 = continuous mode (don't return 0 to signal end-of-file)
 *
 * @returns ==0 end of file
 *           >0 number of bytes read
 *           <0 error
 */
static ssize_t debug_read_helper(struct file *file, char __user *buff,
				 size_t count, loff_t *ppos, int cont)
{
	struct ipc_log_context *ilctxt = file->private_data;
	char *buffer;
	int bsize;

	buffer = kmalloc(count, GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	bsize = debug_log(ilctxt, buffer, count, cont);
	if (bsize > 0) {
		if (copy_to_user(buff, buffer, bsize)) {
			kfree(buffer);
			return -EFAULT;
		}
		*ppos += bsize;
	}
	kfree(buffer);
	return bsize;
}

static ssize_t debug_read(struct file *file, char __user *buff,
			  size_t count, loff_t *ppos)
{
	return debug_read_helper(file, buff, count, ppos, 0);
}

static ssize_t debug_read_cont(struct file *file, char __user *buff,
			       size_t count, loff_t *ppos)
{
	return debug_read_helper(file, buff, count, ppos, 1);
}

static int debug_open(struct inode *inode, struct file *file)
{
	file->private_data = inode->i_private;
	return 0;
}

static const struct file_operations debug_ops = {
	.read = debug_read,
	.open = debug_open,
};

static const struct file_operations debug_ops_cont = {
	.read = debug_read_cont,
	.open = debug_open,
};

static void debug_create(const char *name, mode_t mode,
			 struct dentry *dent,
			 struct ipc_log_context *ilctxt,
			 const struct file_operations *fops)
{
	debugfs_create_file(name, mode, dent, ilctxt, fops);
}

static void dfunc_string(struct encode_context *ectxt,
			 struct decode_context *dctxt)
{
	tsv_timestamp_read(ectxt, dctxt, " ");
	tsv_byte_array_read(ectxt, dctxt, "");

	/* add trailing \n if necessary */
	if (*(dctxt->buff - 1) != '\n') {
		if (dctxt->size) {
			++dctxt->buff;
			--dctxt->size;
		}
		*(dctxt->buff - 1) = '\n';
	}
}

void check_and_create_debugfs(void)
{
	mutex_lock(&ipc_log_debugfs_init_lock);
	if (!root_dent) {
		root_dent = debugfs_create_dir("ipc_logging", 0);

		if (IS_ERR(root_dent)) {
			pr_err("%s: unable to create debugfs %ld\n",
				__func__, IS_ERR(root_dent));
			root_dent = NULL;
		}
	}
	mutex_unlock(&ipc_log_debugfs_init_lock);
}
EXPORT_SYMBOL(check_and_create_debugfs);

void create_ctx_debugfs(struct ipc_log_context *ctxt,
			const char *mod_name)
{
	if (!root_dent)
		check_and_create_debugfs();

	if (root_dent) {
		ctxt->dent = debugfs_create_dir(mod_name, root_dent);
		if (!IS_ERR(ctxt->dent)) {
			debug_create("log", 0444, ctxt->dent,
				     ctxt, &debug_ops);
			debug_create("log_cont", 0444, ctxt->dent,
				     ctxt, &debug_ops_cont);
		}
	}
	add_deserialization_func((void *)ctxt,
				 TSV_TYPE_STRING, dfunc_string);
}
EXPORT_SYMBOL(create_ctx_debugfs);