source: trunk/packages/xen-3.1/xen-3.1/linux-2.6-xen-sparse/drivers/xen/pciback/xenbus.c @ 34

/*
 * PCI Backend Xenbus Setup - handles setup with frontend and xend
 *
 *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <xen/xenbus.h>
#include <xen/evtchn.h>
#include "pciback.h"

#define INVALID_EVTCHN_IRQ  (-1)

static struct pciback_device *alloc_pdev(struct xenbus_device *xdev)
{
        struct pciback_device *pdev;

        pdev = kzalloc(sizeof(struct pciback_device), GFP_KERNEL);
        if (pdev == NULL)
                goto out;
        dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);

        pdev->xdev = xdev;
        xdev->dev.driver_data = pdev;

        spin_lock_init(&pdev->dev_lock);

        pdev->sh_area = NULL;
        pdev->sh_info = NULL;
        pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
        pdev->be_watching = 0;

        INIT_WORK(&pdev->op_work, pciback_do_op, pdev);

        if (pciback_init_devices(pdev)) {
                kfree(pdev);
                pdev = NULL;
        }
      out:
        return pdev;
}

static void free_pdev(struct pciback_device *pdev)
{
        if (pdev->be_watching)
                unregister_xenbus_watch(&pdev->be_watch);

        /* Ensure the guest can't trigger our handler before removing devices */
        if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ)
                unbind_from_irqhandler(pdev->evtchn_irq, pdev);

        /* If the driver domain started an op, make sure we complete it or
         * delete it before releasing the shared memory */
        cancel_delayed_work(&pdev->op_work);
        flush_scheduled_work();

        if (pdev->sh_info)
                xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_area);

        pciback_release_devices(pdev);

        pdev->xdev->dev.driver_data = NULL;
        pdev->xdev = NULL;

        kfree(pdev);
}

static int pciback_do_attach(struct pciback_device *pdev, int gnt_ref,
                             int remote_evtchn)
{
        int err = 0;
        struct vm_struct *area;

        dev_dbg(&pdev->xdev->dev,
                "Attaching to frontend resources - gnt_ref=%d evtchn=%d\n",
                gnt_ref, remote_evtchn);

        area = xenbus_map_ring_valloc(pdev->xdev, gnt_ref);
        if (IS_ERR(area)) {
                err = PTR_ERR(area);
                goto out;
        }
        pdev->sh_area = area;
        pdev->sh_info = area->addr;

        err = bind_interdomain_evtchn_to_irqhandler(
                pdev->xdev->otherend_id, remote_evtchn, pciback_handle_event,
                SA_SAMPLE_RANDOM, "pciback", pdev);
        if (err < 0) {
                xenbus_dev_fatal(pdev->xdev, err,
                                 "Error binding event channel to IRQ");
                goto out;
        }
        pdev->evtchn_irq = err;
        err = 0;

        dev_dbg(&pdev->xdev->dev, "Attached!\n");
      out:
        return err;
}

static int pciback_attach(struct pciback_device *pdev)
{
        int err = 0;
        int gnt_ref, remote_evtchn;
        char *magic = NULL;

        spin_lock(&pdev->dev_lock);

        /* Make sure we only do this setup once */
        if (xenbus_read_driver_state(pdev->xdev->nodename) !=
            XenbusStateInitialised)
                goto out;

        /* Wait for frontend to state that it has published the configuration */
        if (xenbus_read_driver_state(pdev->xdev->otherend) !=
            XenbusStateInitialised)
                goto out;

        dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");

        err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
                            "pci-op-ref", "%u", &gnt_ref,
                            "event-channel", "%u", &remote_evtchn,
                            "magic", NULL, &magic, NULL);
        if (err) {
                /* If configuration didn't get read correctly, wait longer */
                xenbus_dev_fatal(pdev->xdev, err,
                                 "Error reading configuration from frontend");
                goto out;
        }

        if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
                xenbus_dev_fatal(pdev->xdev, -EFAULT,
                                 "version mismatch (%s/%s) with pcifront - "
                                 "halting pciback",
                                 magic, XEN_PCI_MAGIC);
                goto out;
        }

        err = pciback_do_attach(pdev, gnt_ref, remote_evtchn);
        if (err)
                goto out;

        dev_dbg(&pdev->xdev->dev, "Connecting...\n");

        err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
        if (err)
                xenbus_dev_fatal(pdev->xdev, err,
                                 "Error switching to connected state!");

        dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
      out:
        spin_unlock(&pdev->dev_lock);

        if (magic)
                kfree(magic);

        return err;
}

static void pciback_frontend_changed(struct xenbus_device *xdev,
                                     enum xenbus_state fe_state)
{
        struct pciback_device *pdev = xdev->dev.driver_data;

        dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);

        switch (fe_state) {
        case XenbusStateInitialised:
                pciback_attach(pdev);
                break;

        case XenbusStateClosing:
                xenbus_switch_state(xdev, XenbusStateClosing);
                break;

        case XenbusStateUnknown:
        case XenbusStateClosed:
                dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
                device_unregister(&xdev->dev);
                break;

        default:
                break;
        }
}

static int pciback_publish_pci_root(struct pciback_device *pdev,
                                    unsigned int domain, unsigned int bus)
{
        unsigned int d, b;
        int i, root_num, len, err;
        char str[64];

        dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");

        err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
                           "root_num", "%d", &root_num);
        if (err == 0 || err == -ENOENT)
                root_num = 0;
        else if (err < 0)
                goto out;

        /* Verify that we haven't already published this pci root */
        for (i = 0; i < root_num; i++) {
                len = snprintf(str, sizeof(str), "root-%d", i);
                if (unlikely(len >= (sizeof(str) - 1))) {
                        err = -ENOMEM;
                        goto out;
                }

                err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
                                   str, "%x:%x", &d, &b);
                if (err < 0)
                        goto out;
                if (err != 2) {
                        err = -EINVAL;
                        goto out;
                }

                if (d == domain && b == bus) {
                        err = 0;
                        goto out;
                }
        }

        len = snprintf(str, sizeof(str), "root-%d", root_num);
        if (unlikely(len >= (sizeof(str) - 1))) {
                err = -ENOMEM;
                goto out;
        }

        dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
                root_num, domain, bus);

        err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
                            "%04x:%02x", domain, bus);
        if (err)
                goto out;

        err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
                            "root_num", "%d", (root_num + 1));

      out:
        return err;
}

static int pciback_export_device(struct pciback_device *pdev,
                                 int domain, int bus, int slot, int func)
{
        struct pci_dev *dev;
        int err = 0;

        dev_dbg(&pdev->xdev->dev, "exporting dom %x bus %x slot %x func %x\n",
                domain, bus, slot, func);

        dev = pcistub_get_pci_dev_by_slot(pdev, domain, bus, slot, func);
        if (!dev) {
                err = -EINVAL;
                xenbus_dev_fatal(pdev->xdev, err,
                                 "Couldn't locate PCI device "
                                 "(%04x:%02x:%02x.%01x)! "
                                 "perhaps already in-use?",
                                 domain, bus, slot, func);
                goto out;
        }

        err = pciback_add_pci_dev(pdev, dev);
        if (err)
                goto out;

        /* TODO: It'd be nice to export a bridge and have all of its children
         * get exported with it. This may be best done in xend (which will
         * have to calculate resource usage anyway) but we probably want to
         * put something in here to ensure that if a bridge gets given to a
         * driver domain, that all devices under that bridge are not given
         * to other driver domains (as he who controls the bridge can disable
         * it and stop the other devices from working).
         */
      out:
        return err;
}

static int pciback_setup_backend(struct pciback_device *pdev)
{
        /* Get configuration from xend (if available now) */
        int domain, bus, slot, func;
        int err = 0;
        int i, num_devs;
        char dev_str[64];

        spin_lock(&pdev->dev_lock);

        /* It's possible we could get the call to setup twice, so make sure
         * we're not already connected.
         */
        if (xenbus_read_driver_state(pdev->xdev->nodename) !=
            XenbusStateInitWait)
                goto out;

        dev_dbg(&pdev->xdev->dev, "getting be setup\n");

        err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
                           &num_devs);
        if (err != 1) {
                if (err >= 0)
                        err = -EINVAL;
                xenbus_dev_fatal(pdev->xdev, err,
                                 "Error reading number of devices");
                goto out;
        }

        for (i = 0; i < num_devs; i++) {
                int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
                if (unlikely(l >= (sizeof(dev_str) - 1))) {
                        err = -ENOMEM;
                        xenbus_dev_fatal(pdev->xdev, err,
                                         "String overflow while reading "
                                         "configuration");
                        goto out;
                }

                err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
                                   "%x:%x:%x.%x", &domain, &bus, &slot, &func);
                if (err < 0) {
                        xenbus_dev_fatal(pdev->xdev, err,
                                         "Error reading device configuration");
                        goto out;
                }
                if (err != 4) {
                        err = -EINVAL;
                        xenbus_dev_fatal(pdev->xdev, err,
                                         "Error parsing pci device "
                                         "configuration");
                        goto out;
                }

                err = pciback_export_device(pdev, domain, bus, slot, func);
                if (err)
                        goto out;
        }

        err = pciback_publish_pci_roots(pdev, pciback_publish_pci_root);
        if (err) {
                xenbus_dev_fatal(pdev->xdev, err,
                                 "Error while publish PCI root buses "
                                 "for frontend");
                goto out;
        }

        err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
        if (err)
                xenbus_dev_fatal(pdev->xdev, err,
                                 "Error switching to initialised state!");

      out:
        spin_unlock(&pdev->dev_lock);

        if (!err)
                /* see if pcifront is already configured (if not, we'll wait) */
                pciback_attach(pdev);

        return err;
}

static void pciback_be_watch(struct xenbus_watch *watch,
                             const char **vec, unsigned int len)
{
        struct pciback_device *pdev =
            container_of(watch, struct pciback_device, be_watch);

        switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
        case XenbusStateInitWait:
                pciback_setup_backend(pdev);
                break;

        default:
                break;
        }
}

static int pciback_xenbus_probe(struct xenbus_device *dev,
                                const struct xenbus_device_id *id)
{
        int err = 0;
        struct pciback_device *pdev = alloc_pdev(dev);

        if (pdev == NULL) {
                err = -ENOMEM;
                xenbus_dev_fatal(dev, err,
                                 "Error allocating pciback_device struct");
                goto out;
        }

        /* wait for xend to configure us */
        err = xenbus_switch_state(dev, XenbusStateInitWait);
        if (err)
                goto out;

        /* watch the backend node for backend configuration information */
        err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
                                pciback_be_watch);
        if (err)
                goto out;
        pdev->be_watching = 1;

        /* We need to force a call to our callback here in case
         * xend already configured us!
         */
        pciback_be_watch(&pdev->be_watch, NULL, 0);

      out:
        return err;
}

static int pciback_xenbus_remove(struct xenbus_device *dev)
{
        struct pciback_device *pdev = dev->dev.driver_data;

        if (pdev != NULL)
                free_pdev(pdev);

        return 0;
}

static struct xenbus_device_id xenpci_ids[] = {
        {"pci"},
        {{0}},
};

static struct xenbus_driver xenbus_pciback_driver = {
        .name                   = "pciback",
        .owner                  = THIS_MODULE,
        .ids                    = xenpci_ids,
        .probe                  = pciback_xenbus_probe,
        .remove                 = pciback_xenbus_remove,
        .otherend_changed       = pciback_frontend_changed,
};

int __init pciback_xenbus_register(void)
{
        if (!is_running_on_xen())
                return -ENODEV;

        return xenbus_register_backend(&xenbus_pciback_driver);
}

void __exit pciback_xenbus_unregister(void)
{
        xenbus_unregister_driver(&xenbus_pciback_driver);
}