htirq.c

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/*
 * File:    htirq.c
 * Purpose: Hypertransport Interrupt Capability
 *
 * Copyright (C) 2006 Linux Networx
 * Copyright (C) Eric Biederman <[email protected]>
 */

#include <linux/irq.h>
#include <linux/pci.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/htirq.h>

/* Global ht irq lock.
 *
 * This is needed to serialize access to the data port in hypertransport
 * irq capability.
 *
 * With multiple simultaneous hypertransport irq devices it might pay
 * to make this more fine grained.  But start with simple, stupid, and correct.
 */
static DEFINE_SPINLOCK(ht_irq_lock);

struct ht_irq_cfg {
    struct pci_dev *dev;
     /* Update callback used to cope with buggy hardware */
    ht_irq_update_t *update;
    unsigned pos;
    unsigned idx;
    struct ht_irq_msg msg;
};


void write_ht_irq_msg(unsigned int irq, struct ht_irq_msg *msg)
{
    struct ht_irq_cfg *cfg = irq_get_handler_data(irq);
    unsigned long flags;
    spin_lock_irqsave(&ht_irq_lock, flags);
    if (cfg->msg.address_lo != msg->address_lo) {
        pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx);
        pci_write_config_dword(cfg->dev, cfg->pos + 4, msg->address_lo);
    }
    if (cfg->msg.address_hi != msg->address_hi) {
        pci_write_config_byte(cfg->dev, cfg->pos + 2, cfg->idx + 1);
        pci_write_config_dword(cfg->dev, cfg->pos + 4, msg->address_hi);
    }
    if (cfg->update)
        cfg->update(cfg->dev, irq, msg);
    spin_unlock_irqrestore(&ht_irq_lock, flags);
    cfg->msg = *msg;
}

void fetch_ht_irq_msg(unsigned int irq, struct ht_irq_msg *msg)
{
    struct ht_irq_cfg *cfg = irq_get_handler_data(irq);
    *msg = cfg->msg;
}

void mask_ht_irq(struct irq_data *data)
{
    struct ht_irq_cfg *cfg = irq_data_get_irq_handler_data(data);
    struct ht_irq_msg msg = cfg->msg;

    msg.address_lo |= 1;
    write_ht_irq_msg(data->irq, &msg);
}

void unmask_ht_irq(struct irq_data *data)
{
    struct ht_irq_cfg *cfg = irq_data_get_irq_handler_data(data);
    struct ht_irq_msg msg = cfg->msg;

    msg.address_lo &= ~1;
    write_ht_irq_msg(data->irq, &msg);
}

int __ht_create_irq(struct pci_dev *dev, int idx, ht_irq_update_t *update)
{
    struct ht_irq_cfg *cfg;
    unsigned long flags;
    u32 data;
    int max_irq;
    int pos;
    int irq;
    int node;

    pos = pci_find_ht_capability(dev, HT_CAPTYPE_IRQ);
    if (!pos)
        return -EINVAL;

    /* Verify the idx I want to use is in range */
    spin_lock_irqsave(&ht_irq_lock, flags);
    pci_write_config_byte(dev, pos + 2, 1);
    pci_read_config_dword(dev, pos + 4, &data);
    spin_unlock_irqrestore(&ht_irq_lock, flags);

    max_irq = (data >> 16) & 0xff;
    if ( idx > max_irq)
        return -EINVAL;

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

    cfg->dev = dev;
    cfg->update = update;
    cfg->pos = pos;
    cfg->idx = 0x10 + (idx * 2);
    /* Initialize msg to a value that will never match the first write. */
    cfg->msg.address_lo = 0xffffffff;
    cfg->msg.address_hi = 0xffffffff;

    node = dev_to_node(&dev->dev);
    irq = create_irq_nr(0, node);

    if (irq <= 0) {
        kfree(cfg);
        return -EBUSY;
    }
    irq_set_handler_data(irq, cfg);

    if (arch_setup_ht_irq(irq, dev) < 0) {
        ht_destroy_irq(irq);
        return -EBUSY;
    }

    return irq;
}

int ht_create_irq(struct pci_dev *dev, int idx)
{
    return __ht_create_irq(dev, idx, NULL);
}

void ht_destroy_irq(unsigned int irq)
{
    struct ht_irq_cfg *cfg;

    cfg = irq_get_handler_data(irq);
    irq_set_chip(irq, NULL);
    irq_set_handler_data(irq, NULL);
    destroy_irq(irq);

    kfree(cfg);
}

EXPORT_SYMBOL(__ht_create_irq);
EXPORT_SYMBOL(ht_create_irq);
EXPORT_SYMBOL(ht_destroy_irq);