/*
 * Copyright 2012 Cisco Systems, Inc.  All rights reserved.
 *
 * This program is free software; you may redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/debugfs.h>
#include "fnic.h"

static struct dentry *fnic_trace_debugfs_root;
static struct dentry *fnic_trace_debugfs_file;
static struct dentry *fnic_trace_enable;
static struct dentry *fnic_stats_debugfs_root;

/*
 * fnic_debugfs_init - Initialize debugfs for fnic debug logging
 *
 * Description:
 * When Debugfs is configured this routine sets up the fnic debugfs
 * file system. If not already created, this routine will create the
 * fnic directory and statistics directory for trace buffer and
 * stats logging.
 */
int fnic_debugfs_init(void)
{
	int rc = -1;
	fnic_trace_debugfs_root = debugfs_create_dir("fnic", NULL);
	if (!fnic_trace_debugfs_root) {
		printk(KERN_DEBUG "Cannot create debugfs root\n");
		return rc;
	}

	if (!fnic_trace_debugfs_root) {
		printk(KERN_DEBUG
			"fnic root directory doesn't exist in debugfs\n");
		return rc;
	}

	fnic_stats_debugfs_root = debugfs_create_dir("statistics",
						fnic_trace_debugfs_root);
	if (!fnic_stats_debugfs_root) {
		printk(KERN_DEBUG "Cannot create Statistics directory\n");
		return rc;
	}

	rc = 0;
	return rc;
}

/*
 * fnic_debugfs_terminate - Tear down debugfs infrastructure
 *
 * Description:
 * When Debugfs is configured this routine removes debugfs file system
 * elements that are specific to fnic.
 */
void fnic_debugfs_terminate(void)
{
	debugfs_remove(fnic_stats_debugfs_root);
	fnic_stats_debugfs_root = NULL;

	debugfs_remove(fnic_trace_debugfs_root);
	fnic_trace_debugfs_root = NULL;
}

/*
 * fnic_trace_ctrl_open - Open the trace_enable file
 * @inode: The inode pointer.
 * @file: The file pointer to attach the trace enable/disable flag.
 *
 * Description:
 * This routine opens a debugsfs file trace_enable.
 *
 * Returns:
 * This function returns zero if successful.
 */
static int fnic_trace_ctrl_open(struct inode *inode, struct file *filp)
{
	filp->private_data = inode->i_private;
	return 0;
}

/*
 * fnic_trace_ctrl_read - Read a trace_enable debugfs file
 * @filp: The file pointer to read from.
 * @ubuf: The buffer to copy the data to.
 * @cnt: The number of bytes to read.
 * @ppos: The position in the file to start reading from.
 *
 * Description:
 * This routine reads value of variable fnic_tracing_enabled
 * and stores into local @buf. It will start reading file at @ppos and
 * copy up to @cnt of data to @ubuf from @buf.
 *
 * Returns:
 * This function returns the amount of data that was read.
 */
static ssize_t fnic_trace_ctrl_read(struct file *filp,
				  char __user *ubuf,
				  size_t cnt, loff_t *ppos)
{
	char buf[64];
	int len;
	len = sprintf(buf, "%u\n", fnic_tracing_enabled);

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
}

/*
 * fnic_trace_ctrl_write - Write to trace_enable debugfs file
 * @filp: The file pointer to write from.
 * @ubuf: The buffer to copy the data from.
 * @cnt: The number of bytes to write.
 * @ppos: The position in the file to start writing to.
 *
 * Description:
 * This routine writes data from user buffer @ubuf to buffer @buf and
 * sets fnic_tracing_enabled value as per user input.
 *
 * Returns:
 * This function returns the amount of data that was written.
 */
static ssize_t fnic_trace_ctrl_write(struct file *filp,
				  const char __user *ubuf,
				  size_t cnt, loff_t *ppos)
{
	char buf[64];
	unsigned long val;
	int ret;

	if (cnt >= sizeof(buf))
		return -EINVAL;

	if (copy_from_user(&buf, ubuf, cnt))
		return -EFAULT;

	buf[cnt] = 0;

	ret = kstrtoul(buf, 10, &val);
	if (ret < 0)
		return ret;

	fnic_tracing_enabled = val;
	(*ppos)++;

	return cnt;
}

/*
 * fnic_trace_debugfs_open - Open the fnic trace log
 * @inode: The inode pointer
 * @file: The file pointer to attach the log output
 *
 * Description:
 * This routine is the entry point for the debugfs open file operation.
 * It allocates the necessary buffer for the log, fills the buffer from
 * the in-memory log and then returns a pointer to that log in
 * the private_data field in @file.
 *
 * Returns:
 * This function returns zero if successful. On error it will return
 * a negative error value.
 */
static int fnic_trace_debugfs_open(struct inode *inode,
				  struct file *file)
{
	fnic_dbgfs_t *fnic_dbg_prt;
	fnic_dbg_prt = kzalloc(sizeof(fnic_dbgfs_t), GFP_KERNEL);
	if (!fnic_dbg_prt)
		return -ENOMEM;

	fnic_dbg_prt->buffer = vmalloc((3*(trace_max_pages * PAGE_SIZE)));
	if (!fnic_dbg_prt->buffer) {
		kfree(fnic_dbg_prt);
		return -ENOMEM;
	}
	memset((void *)fnic_dbg_prt->buffer, 0,
			  (3*(trace_max_pages * PAGE_SIZE)));
	fnic_dbg_prt->buffer_len = fnic_get_trace_data(fnic_dbg_prt);
	file->private_data = fnic_dbg_prt;
	return 0;
}

/*
 * fnic_trace_debugfs_lseek - Seek through a debugfs file
 * @file: The file pointer to seek through.
 * @offset: The offset to seek to or the amount to seek by.
 * @howto: Indicates how to seek.
 *
 * Description:
 * This routine is the entry point for the debugfs lseek file operation.
 * The @howto parameter indicates whether @offset is the offset to directly
 * seek to, or if it is a value to seek forward or reverse by. This function
 * figures out what the new offset of the debugfs file will be and assigns
 * that value to the f_pos field of @file.
 *
 * Returns:
 * This function returns the new offset if successful and returns a negative
 * error if unable to process the seek.
 */
static loff_t fnic_trace_debugfs_lseek(struct file *file,
					loff_t offset,
					int howto)
{
	fnic_dbgfs_t *fnic_dbg_prt = file->private_data;
	return fixed_size_llseek(file, offset, howto,
				fnic_dbg_prt->buffer_len);
}

/*
 * fnic_trace_debugfs_read - Read a debugfs file
 * @file: The file pointer to read from.
 * @ubuf: The buffer to copy the data to.
 * @nbytes: The number of bytes to read.
 * @pos: The position in the file to start reading from.
 *
 * Description:
 * This routine reads data from the buffer indicated in the private_data
 * field of @file. It will start reading at @pos and copy up to @nbytes of
 * data to @ubuf.
 *
 * Returns:
 * This function returns the amount of data that was read (this could be
 * less than @nbytes if the end of the file was reached).
 */
static ssize_t fnic_trace_debugfs_read(struct file *file,
					char __user *ubuf,
					size_t nbytes,
					loff_t *pos)
{
	fnic_dbgfs_t *fnic_dbg_prt = file->private_data;
	int rc = 0;
	rc = simple_read_from_buffer(ubuf, nbytes, pos,
				  fnic_dbg_prt->buffer,
				  fnic_dbg_prt->buffer_len);
	return rc;
}

/*
 * fnic_trace_debugfs_release - Release the buffer used to store
 * debugfs file data
 * @inode: The inode pointer
 * @file: The file pointer that contains the buffer to release
 *
 * Description:
 * This routine frees the buffer that was allocated when the debugfs
 * file was opened.
 *
 * Returns:
 * This function returns zero.
 */
static int fnic_trace_debugfs_release(struct inode *inode,
					  struct file *file)
{
	fnic_dbgfs_t *fnic_dbg_prt = file->private_data;

	vfree(fnic_dbg_prt->buffer);
	kfree(fnic_dbg_prt);
	return 0;
}

static const struct file_operations fnic_trace_ctrl_fops = {
	.owner = THIS_MODULE,
	.open = fnic_trace_ctrl_open,
	.read = fnic_trace_ctrl_read,
	.write = fnic_trace_ctrl_write,
};

static const struct file_operations fnic_trace_debugfs_fops = {
	.owner = THIS_MODULE,
	.open = fnic_trace_debugfs_open,
	.llseek = fnic_trace_debugfs_lseek,
	.read = fnic_trace_debugfs_read,
	.release = fnic_trace_debugfs_release,
};

/*
 * fnic_trace_debugfs_init - Initialize debugfs for fnic trace logging
 *
 * Description:
 * When Debugfs is configured this routine sets up the fnic debugfs
 * file system. If not already created, this routine will create the
 * create file trace to log fnic trace buffer output into debugfs and
 * it will also create file trace_enable to control enable/disable of
 * trace logging into trace buffer.
 */
int fnic_trace_debugfs_init(void)
{
	int rc = -1;
	if (!fnic_trace_debugfs_root) {
		printk(KERN_DEBUG
			"FNIC Debugfs root directory doesn't exist\n");
		return rc;
	}
	fnic_trace_enable = debugfs_create_file("tracing_enable",
					  S_IFREG|S_IRUGO|S_IWUSR,
					  fnic_trace_debugfs_root,
					  NULL, &fnic_trace_ctrl_fops);

	if (!fnic_trace_enable) {
		printk(KERN_DEBUG
			"Cannot create trace_enable file under debugfs\n");
		return rc;
	}

	fnic_trace_debugfs_file = debugfs_create_file("trace",
						  S_IFREG|S_IRUGO|S_IWUSR,
						  fnic_trace_debugfs_root,
						  NULL,
						  &fnic_trace_debugfs_fops);

	if (!fnic_trace_debugfs_file) {
		printk(KERN_DEBUG
			"Cannot create trace file under debugfs\n");
		return rc;
	}
	rc = 0;
	return rc;
}

/*
 * fnic_trace_debugfs_terminate - Tear down debugfs infrastructure
 *
 * Description:
 * When Debugfs is configured this routine removes debugfs file system
 * elements that are specific to fnic trace logging.
 */
void fnic_trace_debugfs_terminate(void)
{
	if (fnic_trace_debugfs_file) {
		debugfs_remove(fnic_trace_debugfs_file);
		fnic_trace_debugfs_file = NULL;
	}
	if (fnic_trace_enable) {
		debugfs_remove(fnic_trace_enable);
		fnic_trace_enable = NULL;
	}
}

/*
 * fnic_reset_stats_open - Open the reset_stats file
 * @inode: The inode pointer.
 * @file: The file pointer to attach the stats reset flag.
 *
 * Description:
 * This routine opens a debugsfs file reset_stats and stores i_private data
 * to debug structure to retrieve later for while performing other
 * file oprations.
 *
 * Returns:
 * This function returns zero if successful.
 */
static int fnic_reset_stats_open(struct inode *inode, struct file *file)
{
	struct stats_debug_info *debug;

	debug = kzalloc(sizeof(struct stats_debug_info), GFP_KERNEL);
	if (!debug)
		return -ENOMEM;

	debug->i_private = inode->i_private;

	file->private_data = debug;

	return 0;
}

/*
 * fnic_reset_stats_read - Read a reset_stats debugfs file
 * @filp: The file pointer to read from.
 * @ubuf: The buffer to copy the data to.
 * @cnt: The number of bytes to read.
 * @ppos: The position in the file to start reading from.
 *
 * Description:
 * This routine reads value of variable reset_stats
 * and stores into local @buf. It will start reading file at @ppos and
 * copy up to @cnt of data to @ubuf from @buf.
 *
 * Returns:
 * This function returns the amount of data that was read.
 */
static ssize_t fnic_reset_stats_read(struct file *file,
					char __user *ubuf,
					size_t cnt, loff_t *ppos)
{
	struct stats_debug_info *debug = file->private_data;
	struct fnic *fnic = (struct fnic *)debug->i_private;
	char buf[64];
	int len;

	len = sprintf(buf, "%u\n", fnic->reset_stats);

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
}

/*
 * fnic_reset_stats_write - Write to reset_stats debugfs file
 * @filp: The file pointer to write from.
 * @ubuf: The buffer to copy the data from.
 * @cnt: The number of bytes to write.
 * @ppos: The position in the file to start writing to.
 *
 * Description:
 * This routine writes data from user buffer @ubuf to buffer @buf and
 * resets cumulative stats of fnic.
 *
 * Returns:
 * This function returns the amount of data that was written.
 */
static ssize_t fnic_reset_stats_write(struct file *file,
					const char __user *ubuf,
					size_t cnt, loff_t *ppos)
{
	struct stats_debug_info *debug = file->private_data;
	struct fnic *fnic = (struct fnic *)debug->i_private;
	struct fnic_stats *stats = &fnic->fnic_stats;
	u64 *io_stats_p = (u64 *)&stats->io_stats;
	u64 *fw_stats_p = (u64 *)&stats->fw_stats;
	char buf[64];
	unsigned long val;
	int ret;

	if (cnt >= sizeof(buf))
		return -EINVAL;

	if (copy_from_user(&buf, ubuf, cnt))
		return -EFAULT;

	buf[cnt] = 0;

	ret = kstrtoul(buf, 10, &val);
	if (ret < 0)
		return ret;

	fnic->reset_stats = val;

	if (fnic->reset_stats) {
		/* Skip variable is used to avoid descrepancies to Num IOs
		 * and IO Completions stats. Skip incrementing No IO Compls
		 * for pending active IOs after reset stats
		 */
		atomic64_set(&fnic->io_cmpl_skip,
			atomic64_read(&stats->io_stats.active_ios));
		memset(&stats->abts_stats, 0, sizeof(struct abort_stats));
		memset(&stats->term_stats, 0,
			sizeof(struct terminate_stats));
		memset(&stats->reset_stats, 0, sizeof(struct reset_stats));
		memset(&stats->misc_stats, 0, sizeof(struct misc_stats));
		memset(&stats->vlan_stats, 0, sizeof(struct vlan_stats));
		memset(io_stats_p+1, 0,
			sizeof(struct io_path_stats) - sizeof(u64));
		memset(fw_stats_p+1, 0,
			sizeof(struct fw_stats) - sizeof(u64));
	}

	(*ppos)++;
	return cnt;
}

/*
 * fnic_reset_stats_release - Release the buffer used to store
 * debugfs file data
 * @inode: The inode pointer
 * @file: The file pointer that contains the buffer to release
 *
 * Description:
 * This routine frees the buffer that was allocated when the debugfs
 * file was opened.
 *
 * Returns:
 * This function returns zero.
 */
static int fnic_reset_stats_release(struct inode *inode,
					struct file *file)
{
	struct stats_debug_info *debug = file->private_data;
	kfree(debug);
	return 0;
}

/*
 * fnic_stats_debugfs_open - Open the stats file for specific host
 * and get fnic stats.
 * @inode: The inode pointer.
 * @file: The file pointer to attach the specific host statistics.
 *
 * Description:
 * This routine opens a debugsfs file stats of specific host and print
 * fnic stats.
 *
 * Returns:
 * This function returns zero if successful.
 */
static int fnic_stats_debugfs_open(struct inode *inode,
					struct file *file)
{
	struct fnic *fnic = inode->i_private;
	struct fnic_stats *fnic_stats = &fnic->fnic_stats;
	struct stats_debug_info *debug;
	int buf_size = 2 * PAGE_SIZE;

	debug = kzalloc(sizeof(struct stats_debug_info), GFP_KERNEL);
	if (!debug)
		return -ENOMEM;

	debug->debug_buffer = vmalloc(buf_size);
	if (!debug->debug_buffer) {
		kfree(debug);
		return -ENOMEM;
	}

	debug->buf_size = buf_size;
	memset((void *)debug->debug_buffer, 0, buf_size);
	debug->buffer_len = fnic_get_stats_data(debug, fnic_stats);

	file->private_data = debug;

	return 0;
}

/*
 * fnic_stats_debugfs_read - Read a debugfs file
 * @file: The file pointer to read from.
 * @ubuf: The buffer to copy the data to.
 * @nbytes: The number of bytes to read.
 * @pos: The position in the file to start reading from.
 *
 * Description:
 * This routine reads data from the buffer indicated in the private_data
 * field of @file. It will start reading at @pos and copy up to @nbytes of
 * data to @ubuf.
 *
 * Returns:
 * This function returns the amount of data that was read (this could be
 * less than @nbytes if the end of the file was reached).
 */
static ssize_t fnic_stats_debugfs_read(struct file *file,
					char __user *ubuf,
					size_t nbytes,
					loff_t *pos)
{
	struct stats_debug_info *debug = file->private_data;
	int rc = 0;
	rc = simple_read_from_buffer(ubuf, nbytes, pos,
					debug->debug_buffer,
					debug->buffer_len);
	return rc;
}

/*
 * fnic_stats_stats_release - Release the buffer used to store
 * debugfs file data
 * @inode: The inode pointer
 * @file: The file pointer that contains the buffer to release
 *
 * Description:
 * This routine frees the buffer that was allocated when the debugfs
 * file was opened.
 *
 * Returns:
 * This function returns zero.
 */
static int fnic_stats_debugfs_release(struct inode *inode,
					struct file *file)
{
	struct stats_debug_info *debug = file->private_data;
	vfree(debug->debug_buffer);
	kfree(debug);
	return 0;
}

static const struct file_operations fnic_stats_debugfs_fops = {
	.owner = THIS_MODULE,
	.open = fnic_stats_debugfs_open,
	.read = fnic_stats_debugfs_read,
	.release = fnic_stats_debugfs_release,
};

static const struct file_operations fnic_reset_debugfs_fops = {
	.owner = THIS_MODULE,
	.open = fnic_reset_stats_open,
	.read = fnic_reset_stats_read,
	.write = fnic_reset_stats_write,
	.release = fnic_reset_stats_release,
};

/*
 * fnic_stats_init - Initialize stats struct and create stats file per fnic
 *
 * Description:
 * When Debugfs is configured this routine sets up the stats file per fnic
 * It will create file stats and reset_stats under statistics/host# directory
 * to log per fnic stats.
 */
int fnic_stats_debugfs_init(struct fnic *fnic)
{
	int rc = -1;
	char name[16];

	snprintf(name, sizeof(name), "host%d", fnic->lport->host->host_no);

	if (!fnic_stats_debugfs_root) {
		printk(KERN_DEBUG "fnic_stats root doesn't exist\n");
		return rc;
	}
	fnic->fnic_stats_debugfs_host = debugfs_create_dir(name,
						fnic_stats_debugfs_root);
	if (!fnic->fnic_stats_debugfs_host) {
		printk(KERN_DEBUG "Cannot create host directory\n");
		return rc;
	}

	fnic->fnic_stats_debugfs_file = debugfs_create_file("stats",
						S_IFREG|S_IRUGO|S_IWUSR,
						fnic->fnic_stats_debugfs_host,
						fnic,
						&fnic_stats_debugfs_fops);
	if (!fnic->fnic_stats_debugfs_file) {
		printk(KERN_DEBUG "Cannot create host stats file\n");
		return rc;
	}

	fnic->fnic_reset_debugfs_file = debugfs_create_file("reset_stats",
						S_IFREG|S_IRUGO|S_IWUSR,
						fnic->fnic_stats_debugfs_host,
						fnic,
						&fnic_reset_debugfs_fops);
	if (!fnic->fnic_reset_debugfs_file) {
		printk(KERN_DEBUG "Cannot create host stats file\n");
		return rc;
	}
	rc = 0;
	return rc;
}

/*
 * fnic_stats_debugfs_remove - Tear down debugfs infrastructure of stats
 *
 * Description:
 * When Debugfs is configured this routine removes debugfs file system
 * elements that are specific to fnic stats.
 */
void fnic_stats_debugfs_remove(struct fnic *fnic)
{
	if (!fnic)
		return;

	debugfs_remove(fnic->fnic_stats_debugfs_file);
	fnic->fnic_stats_debugfs_file = NULL;

	debugfs_remove(fnic->fnic_reset_debugfs_file);
	fnic->fnic_reset_debugfs_file = NULL;

	debugfs_remove(fnic->fnic_stats_debugfs_host);
	fnic->fnic_stats_debugfs_host = NULL;
}