pmi.c

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/*
 * 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 <[email protected]>
 *
 * 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\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("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 platform_device *dev)
{
    struct device_node *np = dev->dev.of_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 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,
    },
};

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

static void __exit pmi_module_exit(void)
{
    platform_driver_unregister(&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 <[email protected]>");
MODULE_DESCRIPTION("IBM Platform Management Interrupt driver");