msi.c

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/*
 * Copyright 2006 Jake Moilanen <[email protected]>, IBM Corp.
 * Copyright 2006-2007 Michael Ellerman, IBM Corp.
 *
 * 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; version 2 of the
 * License.
 *
 */

#include <linux/device.h>
#include <linux/irq.h>
#include <linux/msi.h>

#include <asm/rtas.h>
#include <asm/hw_irq.h>
#include <asm/ppc-pci.h>

static int query_token, change_token;

#define RTAS_QUERY_FN       0
#define RTAS_CHANGE_FN      1
#define RTAS_RESET_FN       2
#define RTAS_CHANGE_MSI_FN  3
#define RTAS_CHANGE_MSIX_FN 4

static struct pci_dn *get_pdn(struct pci_dev *pdev)
{
    struct device_node *dn;
    struct pci_dn *pdn;

    dn = pci_device_to_OF_node(pdev);
    if (!dn) {
        dev_dbg(&pdev->dev, "rtas_msi: No OF device node\n");
        return NULL;
    }

    pdn = PCI_DN(dn);
    if (!pdn) {
        dev_dbg(&pdev->dev, "rtas_msi: No PCI DN\n");
        return NULL;
    }

    return pdn;
}

/* RTAS Helpers */

static int rtas_change_msi(struct pci_dn *pdn, u32 func, u32 num_irqs)
{
    u32 addr, seq_num, rtas_ret[3];
    unsigned long buid;
    int rc;

    addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
    buid = pdn->phb->buid;

    seq_num = 1;
    do {
        if (func == RTAS_CHANGE_MSI_FN || func == RTAS_CHANGE_MSIX_FN)
            rc = rtas_call(change_token, 6, 4, rtas_ret, addr,
                    BUID_HI(buid), BUID_LO(buid),
                    func, num_irqs, seq_num);
        else
            rc = rtas_call(change_token, 6, 3, rtas_ret, addr,
                    BUID_HI(buid), BUID_LO(buid),
                    func, num_irqs, seq_num);

        seq_num = rtas_ret[1];
    } while (rtas_busy_delay(rc));

    /*
     * If the RTAS call succeeded, return the number of irqs allocated.
     * If not, make sure we return a negative error code.
     */
    if (rc == 0)
        rc = rtas_ret[0];
    else if (rc > 0)
        rc = -rc;

    pr_debug("rtas_msi: ibm,change_msi(func=%d,num=%d), got %d rc = %d\n",
         func, num_irqs, rtas_ret[0], rc);

    return rc;
}

static void rtas_disable_msi(struct pci_dev *pdev)
{
    struct pci_dn *pdn;

    pdn = get_pdn(pdev);
    if (!pdn)
        return;

    /*
     * disabling MSI with the explicit interface also disables MSI-X
     */
    if (rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, 0) != 0) {
        /* 
         * may have failed because explicit interface is not
         * present
         */
        if (rtas_change_msi(pdn, RTAS_CHANGE_FN, 0) != 0) {
            pr_debug("rtas_msi: Setting MSIs to 0 failed!\n");
        }
    }
}

static int rtas_query_irq_number(struct pci_dn *pdn, int offset)
{
    u32 addr, rtas_ret[2];
    unsigned long buid;
    int rc;

    addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
    buid = pdn->phb->buid;

    do {
        rc = rtas_call(query_token, 4, 3, rtas_ret, addr,
                   BUID_HI(buid), BUID_LO(buid), offset);
    } while (rtas_busy_delay(rc));

    if (rc) {
        pr_debug("rtas_msi: error (%d) querying source number\n", rc);
        return rc;
    }

    return rtas_ret[0];
}

static void rtas_teardown_msi_irqs(struct pci_dev *pdev)
{
    struct msi_desc *entry;

    list_for_each_entry(entry, &pdev->msi_list, list) {
        if (entry->irq == NO_IRQ)
            continue;

        irq_set_msi_desc(entry->irq, NULL);
        irq_dispose_mapping(entry->irq);
    }

    rtas_disable_msi(pdev);
}

static int check_req(struct pci_dev *pdev, int nvec, char *prop_name)
{
    struct device_node *dn;
    struct pci_dn *pdn;
    const u32 *req_msi;

    pdn = get_pdn(pdev);
    if (!pdn)
        return -ENODEV;

    dn = pdn->node;

    req_msi = of_get_property(dn, prop_name, NULL);
    if (!req_msi) {
        pr_debug("rtas_msi: No %s on %s\n", prop_name, dn->full_name);
        return -ENOENT;
    }

    if (*req_msi < nvec) {
        pr_debug("rtas_msi: %s requests < %d MSIs\n", prop_name, nvec);

        if (*req_msi == 0) /* Be paranoid */
            return -ENOSPC;

        return *req_msi;
    }

    return 0;
}

static int check_req_msi(struct pci_dev *pdev, int nvec)
{
    return check_req(pdev, nvec, "ibm,req#msi");
}

static int check_req_msix(struct pci_dev *pdev, int nvec)
{
    return check_req(pdev, nvec, "ibm,req#msi-x");
}

/* Quota calculation */

static struct device_node *find_pe_total_msi(struct pci_dev *dev, int *total)
{
    struct device_node *dn;
    const u32 *p;

    dn = of_node_get(pci_device_to_OF_node(dev));
    while (dn) {
        p = of_get_property(dn, "ibm,pe-total-#msi", NULL);
        if (p) {
            pr_debug("rtas_msi: found prop on dn %s\n",
                dn->full_name);
            *total = *p;
            return dn;
        }

        dn = of_get_next_parent(dn);
    }

    return NULL;
}

static struct device_node *find_pe_dn(struct pci_dev *dev, int *total)
{
    struct device_node *dn;
    struct eeh_dev *edev;

    /* Found our PE and assume 8 at that point. */

    dn = pci_device_to_OF_node(dev);
    if (!dn)
        return NULL;

    /* Get the top level device in the PE */
    edev = of_node_to_eeh_dev(dn);
    if (edev->pe)
        edev = list_first_entry(&edev->pe->edevs, struct eeh_dev, list);
    dn = eeh_dev_to_of_node(edev);
    if (!dn)
        return NULL;

    /* We actually want the parent */
    dn = of_get_parent(dn);
    if (!dn)
        return NULL;

    /* Hardcode of 8 for old firmwares */
    *total = 8;
    pr_debug("rtas_msi: using PE dn %s\n", dn->full_name);

    return dn;
}

struct msi_counts {
    struct device_node *requestor;
    int num_devices;
    int request;
    int quota;
    int spare;
    int over_quota;
};

static void *count_non_bridge_devices(struct device_node *dn, void *data)
{
    struct msi_counts *counts = data;
    const u32 *p;
    u32 class;

    pr_debug("rtas_msi: counting %s\n", dn->full_name);

    p = of_get_property(dn, "class-code", NULL);
    class = p ? *p : 0;

    if ((class >> 8) != PCI_CLASS_BRIDGE_PCI)
        counts->num_devices++;

    return NULL;
}

static void *count_spare_msis(struct device_node *dn, void *data)
{
    struct msi_counts *counts = data;
    const u32 *p;
    int req;

    if (dn == counts->requestor)
        req = counts->request;
    else {
        /* We don't know if a driver will try to use MSI or MSI-X,
         * so we just have to punt and use the larger of the two. */
        req = 0;
        p = of_get_property(dn, "ibm,req#msi", NULL);
        if (p)
            req = *p;

        p = of_get_property(dn, "ibm,req#msi-x", NULL);
        if (p)
            req = max(req, (int)*p);
    }

    if (req < counts->quota)
        counts->spare += counts->quota - req;
    else if (req > counts->quota)
        counts->over_quota++;

    return NULL;
}

static int msi_quota_for_device(struct pci_dev *dev, int request)
{
    struct device_node *pe_dn;
    struct msi_counts counts;
    int total;

    pr_debug("rtas_msi: calc quota for %s, request %d\n", pci_name(dev),
          request);

    pe_dn = find_pe_total_msi(dev, &total);
    if (!pe_dn)
        pe_dn = find_pe_dn(dev, &total);

    if (!pe_dn) {
        pr_err("rtas_msi: couldn't find PE for %s\n", pci_name(dev));
        goto out;
    }

    pr_debug("rtas_msi: found PE %s\n", pe_dn->full_name);

    memset(&counts, 0, sizeof(struct msi_counts));

    /* Work out how many devices we have below this PE */
    traverse_pci_devices(pe_dn, count_non_bridge_devices, &counts);

    if (counts.num_devices == 0) {
        pr_err("rtas_msi: found 0 devices under PE for %s\n",
            pci_name(dev));
        goto out;
    }

    counts.quota = total / counts.num_devices;
    if (request <= counts.quota)
        goto out;

    /* else, we have some more calculating to do */
    counts.requestor = pci_device_to_OF_node(dev);
    counts.request = request;
    traverse_pci_devices(pe_dn, count_spare_msis, &counts);

    /* If the quota isn't an integer multiple of the total, we can
     * use the remainder as spare MSIs for anyone that wants them. */
    counts.spare += total % counts.num_devices;

    /* Divide any spare by the number of over-quota requestors */
    if (counts.over_quota)
        counts.quota += counts.spare / counts.over_quota;

    /* And finally clamp the request to the possibly adjusted quota */
    request = min(counts.quota, request);

    pr_debug("rtas_msi: request clamped to quota %d\n", request);
out:
    of_node_put(pe_dn);

    return request;
}

static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
{
    int quota, rc;

    if (type == PCI_CAP_ID_MSIX)
        rc = check_req_msix(pdev, nvec);
    else
        rc = check_req_msi(pdev, nvec);

    if (rc)
        return rc;

    quota = msi_quota_for_device(pdev, nvec);

    if (quota && quota < nvec)
        return quota;

    return 0;
}

static int check_msix_entries(struct pci_dev *pdev)
{
    struct msi_desc *entry;
    int expected;

    /* There's no way for us to express to firmware that we want
     * a discontiguous, or non-zero based, range of MSI-X entries.
     * So we must reject such requests. */

    expected = 0;
    list_for_each_entry(entry, &pdev->msi_list, list) {
        if (entry->msi_attrib.entry_nr != expected) {
            pr_debug("rtas_msi: bad MSI-X entries.\n");
            return -EINVAL;
        }
        expected++;
    }

    return 0;
}

static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
{
    struct pci_dn *pdn;
    int hwirq, virq, i, rc;
    struct msi_desc *entry;
    struct msi_msg msg;
    int nvec = nvec_in;

    pdn = get_pdn(pdev);
    if (!pdn)
        return -ENODEV;

    if (type == PCI_CAP_ID_MSIX && check_msix_entries(pdev))
        return -EINVAL;

    /*
     * Firmware currently refuse any non power of two allocation
     * so we round up if the quota will allow it.
     */
    if (type == PCI_CAP_ID_MSIX) {
        int m = roundup_pow_of_two(nvec);
        int quota = msi_quota_for_device(pdev, m);

        if (quota >= m)
            nvec = m;
    }

    /*
     * Try the new more explicit firmware interface, if that fails fall
     * back to the old interface. The old interface is known to never
     * return MSI-Xs.
     */
again:
    if (type == PCI_CAP_ID_MSI) {
        rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);

        if (rc < 0) {
            pr_debug("rtas_msi: trying the old firmware call.\n");
            rc = rtas_change_msi(pdn, RTAS_CHANGE_FN, nvec);
        }
    } else
        rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);

    if (rc != nvec) {
        if (nvec != nvec_in) {
            nvec = nvec_in;
            goto again;
        }
        pr_debug("rtas_msi: rtas_change_msi() failed\n");
        return rc;
    }

    i = 0;
    list_for_each_entry(entry, &pdev->msi_list, list) {
        hwirq = rtas_query_irq_number(pdn, i++);
        if (hwirq < 0) {
            pr_debug("rtas_msi: error (%d) getting hwirq\n", rc);
            return hwirq;
        }

        virq = irq_create_mapping(NULL, hwirq);

        if (virq == NO_IRQ) {
            pr_debug("rtas_msi: Failed mapping hwirq %d\n", hwirq);
            return -ENOSPC;
        }

        dev_dbg(&pdev->dev, "rtas_msi: allocated virq %d\n", virq);
        irq_set_msi_desc(virq, entry);

        /* Read config space back so we can restore after reset */
        read_msi_msg(virq, &msg);
        entry->msg = msg;
    }

    return 0;
}

static void rtas_msi_pci_irq_fixup(struct pci_dev *pdev)
{
    /* No LSI -> leave MSIs (if any) configured */
    if (pdev->irq == NO_IRQ) {
        dev_dbg(&pdev->dev, "rtas_msi: no LSI, nothing to do.\n");
        return;
    }

    /* No MSI -> MSIs can't have been assigned by fw, leave LSI */
    if (check_req_msi(pdev, 1) && check_req_msix(pdev, 1)) {
        dev_dbg(&pdev->dev, "rtas_msi: no req#msi/x, nothing to do.\n");
        return;
    }

    dev_dbg(&pdev->dev, "rtas_msi: disabling existing MSI.\n");
    rtas_disable_msi(pdev);
}

static int rtas_msi_init(void)
{
    query_token  = rtas_token("ibm,query-interrupt-source-number");
    change_token = rtas_token("ibm,change-msi");

    if ((query_token == RTAS_UNKNOWN_SERVICE) ||
            (change_token == RTAS_UNKNOWN_SERVICE)) {
        pr_debug("rtas_msi: no RTAS tokens, no MSI support.\n");
        return -1;
    }

    pr_debug("rtas_msi: Registering RTAS MSI callbacks.\n");

    WARN_ON(ppc_md.setup_msi_irqs);
    ppc_md.setup_msi_irqs = rtas_setup_msi_irqs;
    ppc_md.teardown_msi_irqs = rtas_teardown_msi_irqs;
    ppc_md.msi_check_device = rtas_msi_check_device;

    WARN_ON(ppc_md.pci_irq_fixup);
    ppc_md.pci_irq_fixup = rtas_msi_pci_irq_fixup;

    return 0;
}
arch_initcall(rtas_msi_init);