// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2006 Jake Moilanen <moilanen@austin.ibm.com>, IBM Corp.
 * Copyright 2006-2007 Michael Ellerman, IBM Corp.
 */

#include <linux/crash_dump.h>
#include <linux/device.h>
#include <linux/irq.h>
#include <linux/irqchip/irq-msi-lib.h>
#include <linux/irqdomain.h>
#include <linux/msi.h>
#include <linux/seq_file.h>

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

#include "pseries.h"

struct pseries_msi_device {
        unsigned int msi_quota;
        unsigned int msi_used;
};

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
#define RTAS_CHANGE_32MSI_FN    5
#define RTAS_CHANGE_32MSIX_FN   6

/* 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 ||
                    func == RTAS_CHANGE_32MSI_FN || func == RTAS_CHANGE_32MSIX_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 = pci_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 int check_req(struct pci_dev *pdev, int nvec, char *prop_name)
{
        struct device_node *dn;
        const __be32 *p;
        u32 req_msi;

        dn = pci_device_to_OF_node(pdev);

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

        req_msi = be32_to_cpup(p);
        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 device_node *node, int *total)
{
        struct device_node *dn;
        const __be32 *p;

        dn = of_node_get(node);
        while (dn) {
                p = of_get_property(dn, "ibm,pe-total-#msi", NULL);
                if (p) {
                        pr_debug("rtas_msi: found prop on dn %pOF\n",
                                dn);
                        *total = be32_to_cpup(p);
                        return dn;
                }

                dn = of_get_next_parent(dn);
        }

        return NULL;
}

static struct device_node *find_pe_total_msi(struct pci_dev *dev, int *total)
{
        return __find_pe_total_msi(pci_device_to_OF_node(dev), total);
}

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 = pdn_to_eeh_dev(PCI_DN(dn));
        if (edev->pe)
                edev = list_first_entry(&edev->pe->edevs, struct eeh_dev,
                                        entry);
        dn = pci_device_to_OF_node(edev->pdev);
        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 %pOF\n", dn);

        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 __be32 *p;
        u32 class;

        pr_debug("rtas_msi: counting %pOF\n", dn);

        p = of_get_property(dn, "class-code", NULL);
        class = p ? be32_to_cpup(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 __be32 *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 = be32_to_cpup(p);

                p = of_get_property(dn, "ibm,req#msi-x", NULL);
                if (p)
                        req = max(req, (int)be32_to_cpup(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 %pOF\n", pe_dn);

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

        /* Work out how many devices we have below this PE */
        pci_traverse_device_nodes(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;
        pci_traverse_device_nodes(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 void rtas_hack_32bit_msi_gen2(struct pci_dev *pdev)
{
        u32 addr_hi, addr_lo;

        /*
         * We should only get in here for IODA1 configs. This is based on the
         * fact that we using RTAS for MSIs, we don't have the 32 bit MSI RTAS
         * support, and we are in a PCIe Gen2 slot.
         */
        dev_info(&pdev->dev,
                 "rtas_msi: No 32 bit MSI firmware support, forcing 32 bit MSI\n");
        pci_read_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, &addr_hi);
        addr_lo = 0xffff0000 | ((addr_hi >> (48 - 32)) << 4);
        pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_LO, addr_lo);
        pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, 0);
}

static int rtas_prepare_msi_irqs(struct pci_dev *pdev, int nvec_in, int type,
                                 msi_alloc_info_t *arg)
{
        struct pci_dn *pdn;
        int quota, rc;
        int nvec = nvec_in;
        int use_32bit_msi_hack = 0;

        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;

        /*
         * 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);
                quota = msi_quota_for_device(pdev, m);

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

        pdn = pci_get_pdn(pdev);

        /*
         * 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) {
                if (pdev->msi_addr_mask < DMA_BIT_MASK(64)) {
                        rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSI_FN, nvec);
                        if (rc < 0) {
                                /*
                                 * We only want to run the 32 bit MSI hack below if
                                 * the max bus speed is Gen2 speed
                                 */
                                if (pdev->bus->max_bus_speed != PCIE_SPEED_5_0GT)
                                        return rc;

                                use_32bit_msi_hack = 1;
                        }
                } else
                        rc = -1;

                if (rc < 0)
                        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);
                }

                if (use_32bit_msi_hack && rc > 0)
                        rtas_hack_32bit_msi_gen2(pdev);
        } else {
                if (pdev->msi_addr_mask < DMA_BIT_MASK(64))
                        rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSIX_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;
        }

        return 0;
}

static int pseries_msi_ops_prepare(struct irq_domain *domain, struct device *dev,
                                   int nvec, msi_alloc_info_t *arg)
{
        struct msi_domain_info *info = domain->host_data;
        struct pci_dev *pdev = to_pci_dev(dev);
        int type = (info->flags & MSI_FLAG_PCI_MSIX) ? PCI_CAP_ID_MSIX : PCI_CAP_ID_MSI;
        int ret;

        struct pseries_msi_device *pseries_dev __free(kfree)
                = kmalloc_obj(*pseries_dev);
        if (!pseries_dev)
                return -ENOMEM;

        while (1) {
                ret = rtas_prepare_msi_irqs(pdev, nvec, type, arg);
                if (!ret)
                        break;
                else if (ret > 0)
                        nvec = ret;
                else
                        return ret;
        }

        pseries_dev->msi_quota = nvec;
        pseries_dev->msi_used = 0;

        arg->scratchpad[0].ptr = no_free_ptr(pseries_dev);
        return 0;
}

/*
 * RTAS can not disable one MSI at a time. It's all or nothing. Do it
 * at the end after all IRQs have been freed.
 */
static void pseries_msi_ops_teardown(struct irq_domain *domain, msi_alloc_info_t *arg)
{
        struct pseries_msi_device *pseries_dev = arg->scratchpad[0].ptr;
        struct pci_dev *pdev = to_pci_dev(domain->dev);

        rtas_disable_msi(pdev);

        WARN_ON(pseries_dev->msi_used);
        kfree(pseries_dev);
}

static void pseries_msi_shutdown(struct irq_data *d)
{
        d = d->parent_data;
        if (d->chip->irq_shutdown)
                d->chip->irq_shutdown(d);
}

static void pseries_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
{
        struct msi_desc *entry = irq_data_get_msi_desc(data);

        /*
         * Do not update the MSIx vector table. It's not strictly necessary
         * because the table is initialized by the underlying hypervisor, PowerVM
         * or QEMU/KVM. However, if the MSIx vector entry is cleared, any further
         * activation will fail. This can happen in some drivers (eg. IPR) which
         * deactivate an IRQ used for testing MSI support.
         */
        entry->msg = *msg;
}

static bool pseries_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
                                      struct irq_domain *real_parent, struct msi_domain_info *info)
{
        struct irq_chip *chip = info->chip;

        if (!msi_lib_init_dev_msi_info(dev, domain, real_parent, info))
                return false;

        chip->irq_shutdown = pseries_msi_shutdown;
        chip->irq_write_msi_msg = pseries_msi_write_msg;

        info->ops->msi_prepare = pseries_msi_ops_prepare;
        info->ops->msi_teardown = pseries_msi_ops_teardown;

        return true;
}

#define PSERIES_PCI_MSI_FLAGS_REQUIRED (MSI_FLAG_USE_DEF_DOM_OPS        | \
                                        MSI_FLAG_USE_DEF_CHIP_OPS       | \
                                        MSI_FLAG_PCI_MSI_MASK_PARENT)
#define PSERIES_PCI_MSI_FLAGS_SUPPORTED (MSI_GENERIC_FLAGS_MASK         | \
                                         MSI_FLAG_PCI_MSIX              | \
                                         MSI_FLAG_MSIX_CONTIGUOUS       | \
                                         MSI_FLAG_MULTI_PCI_MSI)

static const struct msi_parent_ops pseries_msi_parent_ops = {
        .required_flags         = PSERIES_PCI_MSI_FLAGS_REQUIRED,
        .supported_flags        = PSERIES_PCI_MSI_FLAGS_SUPPORTED,
        .chip_flags             = MSI_CHIP_FLAG_SET_EOI,
        .bus_select_token       = DOMAIN_BUS_NEXUS,
        .bus_select_mask        = MATCH_PCI_MSI,
        .prefix                 = "pSeries-",
        .init_dev_msi_info      = pseries_init_dev_msi_info,
};

static void pseries_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
{
        struct pci_dev *dev = msi_desc_to_pci_dev(irq_data_get_msi_desc(data));

        if (dev->current_state == PCI_D0)
                __pci_read_msi_msg(irq_data_get_msi_desc(data), msg);
        else
                get_cached_msi_msg(data->irq, msg);
}

static struct irq_chip pseries_msi_irq_chip = {
        .name                   = "pSeries-MSI",
        .irq_shutdown           = pseries_msi_shutdown,
        .irq_mask               = irq_chip_mask_parent,
        .irq_unmask             = irq_chip_unmask_parent,
        .irq_eoi                = irq_chip_eoi_parent,
        .irq_set_affinity       = irq_chip_set_affinity_parent,
        .irq_compose_msi_msg    = pseries_msi_compose_msg,
};

static int pseries_irq_parent_domain_alloc(struct irq_domain *domain, unsigned int virq,
                                           irq_hw_number_t hwirq)
{
        struct irq_fwspec parent_fwspec;
        int ret;

        parent_fwspec.fwnode = domain->parent->fwnode;
        parent_fwspec.param_count = 2;
        parent_fwspec.param[0] = hwirq;
        parent_fwspec.param[1] = IRQ_TYPE_EDGE_RISING;

        ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &parent_fwspec);
        if (ret)
                return ret;

        return 0;
}

static int pseries_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
                                    unsigned int nr_irqs, void *arg)
{
        struct pci_controller *phb = domain->host_data;
        struct pseries_msi_device *pseries_dev;
        msi_alloc_info_t *info = arg;
        struct msi_desc *desc = info->desc;
        struct pci_dev *pdev = msi_desc_to_pci_dev(desc);
        int hwirq;
        int i, ret;

        pseries_dev = info->scratchpad[0].ptr;

        if (pseries_dev->msi_used + nr_irqs > pseries_dev->msi_quota)
                return -ENOSPC;

        hwirq = rtas_query_irq_number(pci_get_pdn(pdev), desc->msi_index);
        if (hwirq < 0) {
                dev_err(&pdev->dev, "Failed to query HW IRQ: %d\n", hwirq);
                return hwirq;
        }

        dev_dbg(&pdev->dev, "%s bridge %pOF %d/%x #%d\n", __func__,
                phb->dn, virq, hwirq, nr_irqs);

        for (i = 0; i < nr_irqs; i++) {
                ret = pseries_irq_parent_domain_alloc(domain, virq + i, hwirq + i);
                if (ret)
                        goto out;

                irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
                                              &pseries_msi_irq_chip, pseries_dev);
        }

        pseries_dev->msi_used += nr_irqs;
        return 0;

out:
        /* TODO: handle RTAS cleanup in ->msi_finish() ? */
        irq_domain_free_irqs_parent(domain, virq, i);
        return ret;
}

static void pseries_irq_domain_free(struct irq_domain *domain, unsigned int virq,
                                    unsigned int nr_irqs)
{
        struct irq_data *d = irq_domain_get_irq_data(domain, virq);
        struct pseries_msi_device *pseries_dev = irq_data_get_irq_chip_data(d);
        struct pci_controller *phb = domain->host_data;

        pr_debug("%s bridge %pOF %d #%d\n", __func__, phb->dn, virq, nr_irqs);
        pseries_dev->msi_used -= nr_irqs;
        irq_domain_free_irqs_parent(domain, virq, nr_irqs);
}

static const struct irq_domain_ops pseries_irq_domain_ops = {
        .select = msi_lib_irq_domain_select,
        .alloc  = pseries_irq_domain_alloc,
        .free   = pseries_irq_domain_free,
};

static int __pseries_msi_allocate_domains(struct pci_controller *phb,
                                          unsigned int count)
{
        struct irq_domain *parent = irq_get_default_domain();
        struct irq_domain_info info = {
                .fwnode         = of_fwnode_handle(phb->dn),
                .ops            = &pseries_irq_domain_ops,
                .host_data      = phb,
                .size           = count,
                .parent         = parent,
        };

        phb->dev_domain = msi_create_parent_irq_domain(&info, &pseries_msi_parent_ops);
        if (!phb->dev_domain) {
                pr_err("PCI: failed to create MSI IRQ domain bridge %pOF (domain %d)\n",
                       phb->dn, phb->global_number);
                return -ENOMEM;
        }

        return 0;
}

int pseries_msi_allocate_domains(struct pci_controller *phb)
{
        int count;

        if (!__find_pe_total_msi(phb->dn, &count)) {
                pr_err("PCI: failed to find MSIs for bridge %pOF (domain %d)\n",
                       phb->dn, phb->global_number);
                return -ENOSPC;
        }

        return __pseries_msi_allocate_domains(phb, count);
}

void pseries_msi_free_domains(struct pci_controller *phb)
{
        if (phb->dev_domain)
                irq_domain_remove(phb->dev_domain);
}

static void rtas_msi_pci_irq_fixup(struct pci_dev *pdev)
{
        /* No LSI -> leave MSIs (if any) configured */
        if (!pdev->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_function_token(RTAS_FN_IBM_QUERY_INTERRUPT_SOURCE_NUMBER);
        change_token = rtas_function_token(RTAS_FN_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.pci_irq_fixup);
        ppc_md.pci_irq_fixup = rtas_msi_pci_irq_fixup;

        return 0;
}
machine_arch_initcall(pseries, rtas_msi_init);