/*
 * Copyright 2006 Jake Moilanen <moilanen@austin.ibm.com>, 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;

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

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

        dn = find_device_pe(dn);
        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, int type)
{
        struct pci_dn *pdn;
        int hwirq, virq, i, rc;
        struct msi_desc *entry;
        struct msi_msg msg;

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

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

        /*
         * 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.
         */
        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) {
                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);