/*
   * pmi driver
   *
   * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
   *
   * PMI (Platform Management Interrupt) is a way to communicate
   * with the BMC (Baseboard Management Controller) via interrupts.
   * Unlike IPMI it is bidirectional and has a low latency.
   *
   * Author: Christian Krafft <krafft@de.ibm.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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  #include <linux/interrupt.h>
  #include <linux/slab.h>
  #include <linux/completion.h>
  #include <linux/spinlock.h>
  #include <linux/module.h>
  #include <linux/workqueue.h>
  #include <linux/of_device.h>
  #include <linux/of_platform.h>
  
  #include <asm/io.h>
  #include <asm/pmi.h>
  #include <asm/prom.h>
  
  struct pmi_data {
  	struct list_head	handler;
  	spinlock_t		handler_spinlock;
  	spinlock_t		pmi_spinlock;
  	struct mutex		msg_mutex;
  	pmi_message_t		msg;
  	struct completion	*completion;
  	struct platform_device	*dev;
  	int			irq;
  	u8 __iomem		*pmi_reg;
  	struct work_struct	work;
  };
  
  static struct pmi_data *data;
  
  static irqreturn_t pmi_irq_handler(int irq, void *dev_id)
  {
  	u8 type;
  	int rc;
  
  	spin_lock(&data->pmi_spinlock);
  
  	type = ioread8(data->pmi_reg + PMI_READ_TYPE);
  	pr_debug("pmi: got message of type %d
  ", type);
  
  	if (type & PMI_ACK && !data->completion) {
  		printk(KERN_WARNING "pmi: got unexpected ACK message.
  ");
  		rc = -EIO;
  		goto unlock;
  	}
  
  	if (data->completion && !(type & PMI_ACK)) {
  		printk(KERN_WARNING "pmi: expected ACK, but got %d
  ", type);
  		rc = -EIO;
  		goto unlock;
  	}
  
  	data->msg.type = type;
  	data->msg.data0 = ioread8(data->pmi_reg + PMI_READ_DATA0);
  	data->msg.data1 = ioread8(data->pmi_reg + PMI_READ_DATA1);
  	data->msg.data2 = ioread8(data->pmi_reg + PMI_READ_DATA2);
  	rc = 0;
  unlock:
  	spin_unlock(&data->pmi_spinlock);
  
  	if (rc == -EIO) {
  		rc = IRQ_HANDLED;
  		goto out;
  	}
  
  	if (data->msg.type & PMI_ACK) {
  		complete(data->completion);
  		rc = IRQ_HANDLED;
  		goto out;
  	}
  
  	schedule_work(&data->work);
  
  	rc = IRQ_HANDLED;
  out:
  	return rc;
  }
  
  
  static struct of_device_id pmi_match[] = {
  	{ .type = "ibm,pmi", .name = "ibm,pmi" },
  	{ .type = "ibm,pmi" },
  	{},
  };
  
  MODULE_DEVICE_TABLE(of, pmi_match);
  
  static void pmi_notify_handlers(struct work_struct *work)
  {
  	struct pmi_handler *handler;
  
  	spin_lock(&data->handler_spinlock);
  	list_for_each_entry(handler, &data->handler, node) {
  		pr_debug("pmi: notifying handler %p
  ", handler);
  		if (handler->type == data->msg.type)
  			handler->handle_pmi_message(data->msg);
  	}
  	spin_unlock(&data->handler_spinlock);
  }
  
  static int pmi_of_probe(struct platform_device *dev)
  {
  	struct device_node *np = dev->dev.of_node;
  	int rc;
  
  	if (data) {
  		printk(KERN_ERR "pmi: driver has already been initialized.
  ");
  		rc = -EBUSY;
  		goto out;
  	}
  
  	data = kzalloc(sizeof(struct pmi_data), GFP_KERNEL);
  	if (!data) {
  		printk(KERN_ERR "pmi: could not allocate memory.
  ");
  		rc = -ENOMEM;
  		goto out;
  	}
  
  	data->pmi_reg = of_iomap(np, 0);
  	if (!data->pmi_reg) {
  		printk(KERN_ERR "pmi: invalid register address.
  ");
  		rc = -EFAULT;
  		goto error_cleanup_data;
  	}
  
  	INIT_LIST_HEAD(&data->handler);
  
  	mutex_init(&data->msg_mutex);
  	spin_lock_init(&data->pmi_spinlock);
  	spin_lock_init(&data->handler_spinlock);
  
  	INIT_WORK(&data->work, pmi_notify_handlers);
  
  	data->dev = dev;
  
  	data->irq = irq_of_parse_and_map(np, 0);
  	if (data->irq == NO_IRQ) {
  		printk(KERN_ERR "pmi: invalid interrupt.
  ");
  		rc = -EFAULT;
  		goto error_cleanup_iomap;
  	}
  
  	rc = request_irq(data->irq, pmi_irq_handler, 0, "pmi", NULL);
  	if (rc) {
  		printk(KERN_ERR "pmi: can't request IRQ %d: returned %d
  ",
  				data->irq, rc);
  		goto error_cleanup_iomap;
  	}
  
  	printk(KERN_INFO "pmi: found pmi device at addr %p.
  ", data->pmi_reg);
  
  	goto out;
  
  error_cleanup_iomap:
  	iounmap(data->pmi_reg);
  
  error_cleanup_data:
  	kfree(data);
  
  out:
  	return rc;
  }
  
  static int pmi_of_remove(struct platform_device *dev)
  {
  	struct pmi_handler *handler, *tmp;
  
  	free_irq(data->irq, NULL);
  	iounmap(data->pmi_reg);
  
  	spin_lock(&data->handler_spinlock);
  
  	list_for_each_entry_safe(handler, tmp, &data->handler, node)
  		list_del(&handler->node);
  
  	spin_unlock(&data->handler_spinlock);
  
  	kfree(data);
  	data = NULL;
  
  	return 0;
  }
  
  static struct platform_driver pmi_of_platform_driver = {
  	.probe		= pmi_of_probe,
  	.remove		= pmi_of_remove,
  	.driver = {
  		.name = "pmi",
  		.owner = THIS_MODULE,
  		.of_match_table = pmi_match,
  	},
  };
  module_platform_driver(pmi_of_platform_driver);
  
  int pmi_send_message(pmi_message_t msg)
  {
  	unsigned long flags;
  	DECLARE_COMPLETION_ONSTACK(completion);
  
  	if (!data)
  		return -ENODEV;
  
  	mutex_lock(&data->msg_mutex);
  
  	data->msg = msg;
  	pr_debug("pmi_send_message: msg is %08x
  ", *(u32*)&msg);
  
  	data->completion = &completion;
  
  	spin_lock_irqsave(&data->pmi_spinlock, flags);
  	iowrite8(msg.data0, data->pmi_reg + PMI_WRITE_DATA0);
  	iowrite8(msg.data1, data->pmi_reg + PMI_WRITE_DATA1);
  	iowrite8(msg.data2, data->pmi_reg + PMI_WRITE_DATA2);
  	iowrite8(msg.type, data->pmi_reg + PMI_WRITE_TYPE);
  	spin_unlock_irqrestore(&data->pmi_spinlock, flags);
  
  	pr_debug("pmi_send_message: wait for completion
  ");
  
  	wait_for_completion_interruptible_timeout(data->completion,
  						  PMI_TIMEOUT);
  
  	data->completion = NULL;
  
  	mutex_unlock(&data->msg_mutex);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pmi_send_message);
  
  int pmi_register_handler(struct pmi_handler *handler)
  {
  	if (!data)
  		return -ENODEV;
  
  	spin_lock(&data->handler_spinlock);
  	list_add_tail(&handler->node, &data->handler);
  	spin_unlock(&data->handler_spinlock);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pmi_register_handler);
  
  void pmi_unregister_handler(struct pmi_handler *handler)
  {
  	if (!data)
  		return;
  
  	pr_debug("pmi: unregistering handler %p
  ", handler);
  
  	spin_lock(&data->handler_spinlock);
  	list_del(&handler->node);
  	spin_unlock(&data->handler_spinlock);
  }
  EXPORT_SYMBOL_GPL(pmi_unregister_handler);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
  MODULE_DESCRIPTION("IBM Platform Management Interrupt driver");