ibmasmfs.c

linux-2.6.15.6

/*
 * IBM ASM Service Processor Device Driver
 *
 * 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2004
 *
 * Author: Max Asb鯿k <[e-mail]> 
 *
 */

/*
 * Parts of this code are based on an article by Jonathan Corbet 
 * that appeared in Linux Weekly News.
 */


/*
 * The IBMASM file virtual filesystem. It creates the following hierarchy
 * dymamically when mounted from user space:
 *
 *    /ibmasm
 *    |-- 0
 *    |   |-- command
 *    |   |-- event
 *    |   |-- reverse_heartbeat
 *    |   `-- remote_video
 *    |       |-- depth
 *    |       |-- height
 *    |       `-- width
 *    .
 *    .
 *    .
 *    `-- n
 *        |-- command
 *        |-- event
 *        |-- reverse_heartbeat
 *        `-- remote_video
 *            |-- depth
 *            |-- height
 *            `-- width
 *
 * For each service processor the following files are created:
 *
 * command: execute dot commands
 * 	write: execute a dot command on the service processor
 * 	read: return the result of a previously executed dot command
 *
 * events: listen for service processor events
 * 	read: sleep (interruptible) until an event occurs
 *      write: wakeup sleeping event listener
 *
 * reverse_heartbeat: send a heartbeat to the service processor
 * 	read: sleep (interruptible) until the reverse heartbeat fails
 *      write: wakeup sleeping heartbeat listener
 *
 * remote_video/width
 * remote_video/height
 * remote_video/width: control remote display settings
 * 	write: set value
 * 	read: read value
 */

#include <linux/fs.h>
#include <linux/pagemap.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include "ibmasm.h"
#include "remote.h"
#include "dot_command.h"

#define IBMASMFS_MAGIC 0x66726f67

static LIST_HEAD(service_processors);

static struct inode *ibmasmfs_make_inode(struct super_block *sb, int mode);
static void ibmasmfs_create_files (struct super_block *sb, struct dentry *root);
static int ibmasmfs_fill_super (struct super_block *sb, void *data, int silent);


static struct super_block *ibmasmfs_get_super(struct file_system_type *fst,
			int flags, const char *name, void *data)
{
	return get_sb_single(fst, flags, data, ibmasmfs_fill_super);
}

static struct super_operations ibmasmfs_s_ops = {
	.statfs		= simple_statfs,
	.drop_inode	= generic_delete_inode,
};

static struct file_operations *ibmasmfs_dir_ops = &simple_dir_operations;

static struct file_system_type ibmasmfs_type = {
	.owner          = THIS_MODULE,
	.name           = "ibmasmfs",
	.get_sb         = ibmasmfs_get_super,
	.kill_sb        = kill_litter_super,
};

static int ibmasmfs_fill_super (struct super_block *sb, void *data, int silent)
{
	struct inode *root;
	struct dentry *root_dentry;

	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = IBMASMFS_MAGIC;
	sb->s_op = &ibmasmfs_s_ops;
	sb->s_time_gran = 1;

	root = ibmasmfs_make_inode (sb, S_IFDIR | 0500);
	if (!root)
		return -ENOMEM;

	root->i_op = &simple_dir_inode_operations;
	root->i_fop = ibmasmfs_dir_ops;

	root_dentry = d_alloc_root(root);
	if (!root_dentry) {
		iput(root);
		return -ENOMEM;
	}
	sb->s_root = root_dentry;

	ibmasmfs_create_files(sb, root_dentry);
	return 0;
}

static struct inode *ibmasmfs_make_inode(struct super_block *sb, int mode)
{
	struct inode *ret = new_inode(sb);

	if (ret) {
		ret->i_mode = mode;
		ret->i_uid = ret->i_gid = 0;
		ret->i_blksize = PAGE_CACHE_SIZE;
		ret->i_blocks = 0;
		ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
	}
	return ret;
}

static struct dentry *ibmasmfs_create_file (struct super_block *sb,
			struct dentry *parent,
		       	const char *name,
			struct file_operations *fops,
			void *data,
			int mode)
{
	struct dentry *dentry;
	struct inode *inode;

	dentry = d_alloc_name(parent, name);
	if (!dentry)
		return NULL;

	inode = ibmasmfs_make_inode(sb, S_IFREG | mode);
	if (!inode) {
		dput(dentry);
		return NULL;
	}

	inode->i_fop = fops;
	inode->u.generic_ip = data;

	d_add(dentry, inode);
	return dentry;
}

static struct dentry *ibmasmfs_create_dir (struct super_block *sb,
				struct dentry *parent,
				const char *name)
{
	struct dentry *dentry;
	struct inode *inode;

	dentry = d_alloc_name(parent, name);
	if (!dentry)
		return NULL;

	inode = ibmasmfs_make_inode(sb, S_IFDIR | 0500);
	if (!inode) {
		dput(dentry);
		return NULL;
	}

	inode->i_op = &simple_dir_inode_operations;
	inode->i_fop = ibmasmfs_dir_ops;

	d_add(dentry, inode);
	return dentry;
}

int ibmasmfs_register(void)
{
	return register_filesystem(&ibmasmfs_type);
}

void ibmasmfs_unregister(void)
{
	unregister_filesystem(&ibmasmfs_type);
}

void ibmasmfs_add_sp(struct service_processor *sp)
{
	list_add(&sp->node, &service_processors);
}

/* struct to save state between command file operations */
struct ibmasmfs_command_data {
	struct service_processor	*sp;
	struct command			*command;
};

/* struct to save state between event file operations */
struct ibmasmfs_event_data {
	struct service_processor	*sp;
	struct event_reader		reader;
	int				active;
};

/* struct to save state between reverse heartbeat file operations */
struct ibmasmfs_heartbeat_data {
	struct service_processor	*sp;
	struct reverse_heartbeat	heartbeat;
	int				active;
};

static int command_file_open(struct inode *inode, struct file *file)
{
	struct ibmasmfs_command_data *command_data;

	if (!inode->u.generic_ip)
		return -ENODEV;

	command_data = kmalloc(sizeof(struct ibmasmfs_command_data), GFP_KERNEL);
	if (!command_data)
		return -ENOMEM;

	command_data->command = NULL;
	command_data->sp = inode->u.generic_ip;
	file->private_data = command_data;
	return 0;
}

static int command_file_close(struct inode *inode, struct file *file)
{
	struct ibmasmfs_command_data *command_data = file->private_data;

	if (command_data->command)
		command_put(command_data->command);	

	kfree(command_data);
	return 0;
}

static ssize_t command_file_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
	struct ibmasmfs_command_data *command_data = file->private_data;
	struct command *cmd;
	int len;
	unsigned long flags;

	if (*offset < 0)
		return -EINVAL;
	if (count == 0 || count > IBMASM_CMD_MAX_BUFFER_SIZE)
		return 0;
	if (*offset != 0)
		return 0;

	spin_lock_irqsave(&command_data->sp->lock, flags);
	cmd = command_data->command;
	if (cmd == NULL) {
		spin_unlock_irqrestore(&command_data->sp->lock, flags);
		return 0;
	}
	command_data->command = NULL;
	spin_unlock_irqrestore(&command_data->sp->lock, flags);

	if (cmd->status != IBMASM_CMD_COMPLETE) {
		command_put(cmd);
		return -EIO;
	}
	len = min(count, cmd->buffer_size);
	if (copy_to_user(buf, cmd->buffer, len)) {
		command_put(cmd);
		return -EFAULT;
	}
	command_put(cmd);

	return len;
}

static ssize_t command_file_write(struct file *file, const char __user *ubuff, size_t count, loff_t *offset)
{
	struct ibmasmfs_command_data *command_data = file->private_data;
	struct command *cmd;
	unsigned long flags;

	if (*offset < 0)
		return -EINVAL;
	if (count == 0 || count > IBMASM_CMD_MAX_BUFFER_SIZE)
		return 0;
	if (*offset != 0)
		return 0;

	/* commands are executed sequentially, only one command at a time */