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pmi.c

/*
 * 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/completion.h>
#include <linux/spinlock.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 of_device  *dev;
      int               irq;
      u8 __iomem        *pmi_reg;
      struct work_struct      work;
};

static struct pmi_data *data;

static int 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\n", type);

      if (type & PMI_ACK && !data->completion) {
            printk(KERN_WARNING "pmi: got unexpected ACK message.\n");
            rc = -EIO;
            goto unlock;
      }

      if (data->completion && !(type & PMI_ACK)) {
            printk(KERN_WARNING "pmi: expected ACK, but got %d\n", 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(KERN_INFO "pmi: notifying handler %p\n", handler);
            if (handler->type == data->msg.type)
                  handler->handle_pmi_message(data->msg);
      }
      spin_unlock(&data->handler_spinlock);
}

static int pmi_of_probe(struct of_device *dev,
                  const struct of_device_id *match)
{
      struct device_node *np = dev->node;
      int rc;

      if (data) {
            printk(KERN_ERR "pmi: driver has already been initialized.\n");
            rc = -EBUSY;
            goto out;
      }

      data = kzalloc(sizeof(struct pmi_data), GFP_KERNEL);
      if (!data) {
            printk(KERN_ERR "pmi: could not allocate memory.\n");
            rc = -ENOMEM;
            goto out;
      }

      data->pmi_reg = of_iomap(np, 0);
      if (!data->pmi_reg) {
            printk(KERN_ERR "pmi: invalid register address.\n");
            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.\n");
            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\n",
                        data->irq, rc);
            goto error_cleanup_iomap;
      }

      printk(KERN_INFO "pmi: found pmi device at addr %p.\n", 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 of_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 of_platform_driver pmi_of_platform_driver = {
      .match_table      = pmi_match,
      .probe            = pmi_of_probe,
      .remove           = pmi_of_remove,
      .driver           = {
            .name = "pmi",
      },
};

static int __init pmi_module_init(void)
{
      return of_register_platform_driver(&pmi_of_platform_driver);
}
module_init(pmi_module_init);

static void __exit pmi_module_exit(void)
{
      of_unregister_platform_driver(&pmi_of_platform_driver);
}
module_exit(pmi_module_exit);

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\n", *(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\n");

      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\n", 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");

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