/*
 *	Functions to handle I2O drivers (OSMs) and I2O bus type for sysfs
 *
 *	Copyright (C) 2004	Markus Lidel <Markus.Lidel@shadowconnect.com>
 *
 *	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.
 *
 *	Fixes/additions:
 *		Markus Lidel <Markus.Lidel@shadowconnect.com>
 *			initial version.
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/rwsem.h>
#include <linux/i2o.h>

/* max_drivers - Maximum I2O drivers (OSMs) which could be registered */
unsigned int i2o_max_drivers = I2O_MAX_DRIVERS;
module_param_named(max_drivers, i2o_max_drivers, uint, 0);
MODULE_PARM_DESC(max_drivers, "maximum number of OSM's to support");

/* I2O drivers lock and array */
static spinlock_t i2o_drivers_lock;
static struct i2o_driver **i2o_drivers;

/**
 *	i2o_bus_match - Tell if a I2O device class id match the class ids of
 *			the I2O driver (OSM)
 *
 *	@dev: device which should be verified
 *	@drv: the driver to match against
 *
 *	Used by the bus to check if the driver wants to handle the device.
 *
 *	Returns 1 if the class ids of the driver match the class id of the
 *	device, otherwise 0.
 */
static int i2o_bus_match(struct device *dev, struct device_driver *drv)
{
	struct i2o_device *i2o_dev = to_i2o_device(dev);
	struct i2o_driver *i2o_drv = to_i2o_driver(drv);
	struct i2o_class_id *ids = i2o_drv->classes;

	if (ids)
		while (ids->class_id != I2O_CLASS_END) {
			if (ids->class_id == i2o_dev->lct_data.class_id)
				return 1;
			ids++;
		}
	return 0;
};

/* I2O bus type */
struct bus_type i2o_bus_type = {
	.name = "i2o",
	.match = i2o_bus_match,
};

/**
 *	i2o_driver_register - Register a I2O driver (OSM) in the I2O core
 *	@drv: I2O driver which should be registered
 *
 *	Registers the OSM drv in the I2O core and creates an event queues if
 *	necessary.
 *
 *	Returns 0 on success or negative error code on failure.
 */
int i2o_driver_register(struct i2o_driver *drv)
{
	struct i2o_controller *c;
	int i;
	int rc = 0;
	unsigned long flags;

	pr_debug("i2o: Register driver %s\n", drv->name);

	if (drv->event) {
		drv->event_queue = create_workqueue(drv->name);
		if (!drv->event_queue) {
			printk(KERN_ERR "i2o: Could not initialize event queue "
			       "for driver %s\n", drv->name);
			return -EFAULT;
		}
		pr_debug("i2o: Event queue initialized for driver %s\n",
			 drv->name);
	} else
		drv->event_queue = NULL;

	drv->driver.name = drv->name;
	drv->driver.bus = &i2o_bus_type;

	spin_lock_irqsave(&i2o_drivers_lock, flags);

	for (i = 0; i2o_drivers[i]; i++)
		if (i >= i2o_max_drivers) {
			printk(KERN_ERR "i2o: too many drivers registered, "
			       "increase max_drivers\n");
			spin_unlock_irqrestore(&i2o_drivers_lock, flags);
			return -EFAULT;
		}

	drv->context = i;
	i2o_drivers[i] = drv;

	spin_unlock_irqrestore(&i2o_drivers_lock, flags);

	pr_debug("i2o: driver %s gets context id %d\n", drv->name,
		 drv->context);

	list_for_each_entry(c, &i2o_controllers, list) {
		struct i2o_device *i2o_dev;

		i2o_driver_notify_controller_add(drv, c);
		list_for_each_entry(i2o_dev, &c->devices, list)
			i2o_driver_notify_device_add(drv, i2o_dev);
	}


	rc = driver_register(&drv->driver);
	if (rc)
		destroy_workqueue(drv->event_queue);

	return rc;
};

/**
 *	i2o_driver_unregister - Unregister a I2O driver (OSM) from the I2O core
 *	@drv: I2O driver which should be unregistered
 *
 *	Unregisters the OSM drv from the I2O core and cleanup event queues if
 *	necessary.
 */
void i2o_driver_unregister(struct i2o_driver *drv)
{
	struct i2o_controller *c;
	unsigned long flags;

	pr_debug("i2o: unregister driver %s\n", drv->name);

	driver_unregister(&drv->driver);

	list_for_each_entry(c, &i2o_controllers, list) {
		struct i2o_device *i2o_dev;

		list_for_each_entry(i2o_dev, &c->devices, list)
		    i2o_driver_notify_device_remove(drv, i2o_dev);

		i2o_driver_notify_controller_remove(drv, c);
	}

	spin_lock_irqsave(&i2o_drivers_lock, flags);
	i2o_drivers[drv->context] = NULL;
	spin_unlock_irqrestore(&i2o_drivers_lock, flags);

	if (drv->event_queue) {
		destroy_workqueue(drv->event_queue);
		drv->event_queue = NULL;
		pr_debug("i2o: event queue removed for %s\n", drv->name);
	}
};

/**
 *	i2o_driver_dispatch - dispatch an I2O reply message
 *	@c: I2O controller of the message
 *	@m: I2O message number
 *	@msg: I2O message to be delivered
 *
 *	The reply is delivered to the driver from which the original message
 *	was. This function is only called from interrupt context.
 *
 *	Returns 0 on success and the message should not be flushed. Returns > 0
 *	on success and if the message should be flushed afterwords. Returns
 *	negative error code on failure (the message will be flushed too).
 */
int i2o_driver_dispatch(struct i2o_controller *c, u32 m,
			struct i2o_message __iomem *msg)
{
	struct i2o_driver *drv;
	u32 context = readl(&msg->u.s.icntxt);

	if (likely(context < i2o_max_drivers)) {
		spin_lock(&i2o_drivers_lock);
		drv = i2o_drivers[context];
		spin_unlock(&i2o_drivers_lock);

		if (unlikely(!drv)) {
			printk(KERN_WARNING "%s: Spurious reply to unknown "
			       "driver %d\n", c->name, context);
			return -EIO;
		}

		if ((readl(&msg->u.head[1]) >> 24) == I2O_CMD_UTIL_EVT_REGISTER) {
			struct i2o_device *dev, *tmp;
			struct i2o_event *evt;
			u16 size;
			u16 tid;

			tid = readl(&msg->u.head[1]) & 0x1fff;

			pr_debug("%s: event received from device %d\n", c->name,
				 tid);

			/* cut of header from message size (in 32-bit words) */
			size = (readl(&msg->u.head[0]) >> 16) - 5;

			evt = kmalloc(size * 4 + sizeof(*evt), GFP_ATOMIC);
			if (!evt)
				return -ENOMEM;
			memset(evt, 0, size * 4 + sizeof(*evt));

			evt->size = size;
			memcpy_fromio(&evt->tcntxt, &msg->u.s.tcntxt,
				      (size + 2) * 4);

			list_for_each_entry_safe(dev, tmp, &c->devices, list)
			    if (dev->lct_data.tid == tid) {
				evt->i2o_dev = dev;
				break;
			}

			INIT_WORK(&evt->work, (void (*)(void *))drv->event,
				  evt);
			queue_work(drv->event_queue, &evt->work);
			return 1;
		}

		if (likely(drv->reply))
			return drv->reply(c, m, msg);
		else
			pr_debug("%s: Reply to driver %s, but no reply function"
				 " defined!\n", c->name, drv->name);
		return -EIO;
	} else
		printk(KERN_WARNING "%s: Spurious reply to unknown driver "
		       "%d\n", c->name, readl(&msg->u.s.icntxt));
	return -EIO;
}

/**
 *	i2o_driver_notify_controller_add_all - Send notify of added controller
 *					       to all I2O drivers
 *
 *	Send notifications to all registered drivers that a new controller was
 *	added.
 */
void i2o_driver_notify_controller_add_all(struct i2o_controller *c)
{
	int i;
	struct i2o_driver *drv;

	for (i = 0; i < I2O_MAX_DRIVERS; i++) {
		drv = i2o_drivers[i];

		if (drv)
			i2o_driver_notify_controller_add(drv, c);
	}
}

/**
 *	i2o_driver_notify_controller_remove_all - Send notify of removed
 *						  controller to all I2O drivers
 *
 *	Send notifications to all registered drivers that a controller was
 *	removed.
 */
void i2o_driver_notify_controller_remove_all(struct i2o_controller *c)
{
	int i;
	struct i2o_driver *drv;

	for (i = 0; i < I2O_MAX_DRIVERS; i++) {
		drv = i2o_drivers[i];

		if (drv)
			i2o_driver_notify_controller_remove(drv, c);
	}
}

/**
 *	i2o_driver_notify_device_add_all - Send notify of added device to all
 *					   I2O drivers
 *
 *	Send notifications to all registered drivers that a device was added.
 */
void i2o_driver_notify_device_add_all(struct i2o_device *i2o_dev)
{
	int i;
	struct i2o_driver *drv;

	for (i = 0; i < I2O_MAX_DRIVERS; i++) {
		drv = i2o_drivers[i];

		if (drv)
			i2o_driver_notify_device_add(drv, i2o_dev);
	}
}

/**
 *	i2o_driver_notify_device_remove_all - Send notify of removed device to
 *					      all I2O drivers
 *
 *	Send notifications to all registered drivers that a device was removed.
 */
void i2o_driver_notify_device_remove_all(struct i2o_device *i2o_dev)
{
	int i;
	struct i2o_driver *drv;

	for (i = 0; i < I2O_MAX_DRIVERS; i++) {
		drv = i2o_drivers[i];

		if (drv)
			i2o_driver_notify_device_remove(drv, i2o_dev);
	}
}

/**
 *	i2o_driver_init - initialize I2O drivers (OSMs)
 *
 *	Registers the I2O bus and allocate memory for the array of OSMs.
 *
 *	Returns 0 on success or negative error code on failure.
 */
int __init i2o_driver_init(void)
{
	int rc = 0;

	spin_lock_init(&i2o_drivers_lock);

	if ((i2o_max_drivers < 2) || (i2o_max_drivers > 64) ||
	    ((i2o_max_drivers ^ (i2o_max_drivers - 1)) !=
	     (2 * i2o_max_drivers - 1))) {
		printk(KERN_WARNING "i2o: max_drivers set to %d, but must be "
		       ">=2 and <= 64 and a power of 2\n", i2o_max_drivers);
		i2o_max_drivers = I2O_MAX_DRIVERS;
	}
	printk(KERN_INFO "i2o: max drivers = %d\n", i2o_max_drivers);

	i2o_drivers =
	    kmalloc(i2o_max_drivers * sizeof(*i2o_drivers), GFP_KERNEL);
	if (!i2o_drivers)
		return -ENOMEM;

	memset(i2o_drivers, 0, i2o_max_drivers * sizeof(*i2o_drivers));

	rc = bus_register(&i2o_bus_type);

	if (rc < 0)
		kfree(i2o_drivers);

	return rc;
};

/**
 *	i2o_driver_exit - clean up I2O drivers (OSMs)
 *
 *	Unregisters the I2O bus and free driver array.
 */
void __exit i2o_driver_exit(void)
{
	bus_unregister(&i2o_bus_type);
	kfree(i2o_drivers);
};

EXPORT_SYMBOL(i2o_driver_register);
EXPORT_SYMBOL(i2o_driver_unregister);
EXPORT_SYMBOL(i2o_driver_notify_controller_add_all);
EXPORT_SYMBOL(i2o_driver_notify_controller_remove_all);
EXPORT_SYMBOL(i2o_driver_notify_device_add_all);
EXPORT_SYMBOL(i2o_driver_notify_device_remove_all);