// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2025 Arm Ltd.

/* Parse the MPAM ACPI table feeding the discovered nodes into the driver */

#define pr_fmt(fmt) "ACPI MPAM: " fmt

#include <linux/acpi.h>
#include <linux/arm_mpam.h>
#include <linux/bits.h>
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/platform_device.h>

#include <acpi/processor.h>

/*
 * Flags for acpi_table_mpam_msc.*_interrupt_flags.
 * See 2.1.1 Interrupt Flags, Table 5, of DEN0065B_MPAM_ACPI_3.0-bet.
 */
#define ACPI_MPAM_MSC_IRQ_MODE                              BIT(0)
#define ACPI_MPAM_MSC_IRQ_TYPE_MASK                         GENMASK(2, 1)
#define ACPI_MPAM_MSC_IRQ_TYPE_WIRED                        0
#define ACPI_MPAM_MSC_IRQ_AFFINITY_TYPE_MASK                BIT(3)
#define ACPI_MPAM_MSC_IRQ_AFFINITY_TYPE_PROCESSOR           0
#define ACPI_MPAM_MSC_IRQ_AFFINITY_TYPE_PROCESSOR_CONTAINER 1
#define ACPI_MPAM_MSC_IRQ_AFFINITY_VALID                    BIT(4)

/*
 * Encodings for the MSC node body interface type field.
 * See 2.1 MPAM MSC node, Table 4 of DEN0065B_MPAM_ACPI_3.0-bet.
 */
#define ACPI_MPAM_MSC_IFACE_MMIO   0x00
#define ACPI_MPAM_MSC_IFACE_PCC    0x0a

static bool _is_ppi_partition(u32 flags)
{
        u32 aff_type, is_ppi;
        bool ret;

        is_ppi = FIELD_GET(ACPI_MPAM_MSC_IRQ_AFFINITY_VALID, flags);
        if (!is_ppi)
                return false;

        aff_type = FIELD_GET(ACPI_MPAM_MSC_IRQ_AFFINITY_TYPE_MASK, flags);
        ret = (aff_type == ACPI_MPAM_MSC_IRQ_AFFINITY_TYPE_PROCESSOR_CONTAINER);
        if (ret)
                pr_err_once("Partitioned interrupts not supported\n");

        return ret;
}

static int acpi_mpam_register_irq(struct platform_device *pdev,
                                  u32 intid, u32 flags)
{
        int irq;
        u32 int_type;
        int trigger;

        if (!intid)
                return -EINVAL;

        if (_is_ppi_partition(flags))
                return -EINVAL;

        trigger = FIELD_GET(ACPI_MPAM_MSC_IRQ_MODE, flags);
        int_type = FIELD_GET(ACPI_MPAM_MSC_IRQ_TYPE_MASK, flags);
        if (int_type != ACPI_MPAM_MSC_IRQ_TYPE_WIRED)
                return -EINVAL;

        irq = acpi_register_gsi(&pdev->dev, intid, trigger, ACPI_ACTIVE_HIGH);
        if (irq < 0)
                pr_err_once("Failed to register interrupt 0x%x with ACPI\n", intid);

        return irq;
}

static void acpi_mpam_parse_irqs(struct platform_device *pdev,
                                 struct acpi_mpam_msc_node *tbl_msc,
                                 struct resource *res, int *res_idx)
{
        u32 flags, intid;
        int irq;

        intid = tbl_msc->overflow_interrupt;
        flags = tbl_msc->overflow_interrupt_flags;
        irq = acpi_mpam_register_irq(pdev, intid, flags);
        if (irq > 0)
                res[(*res_idx)++] = DEFINE_RES_IRQ_NAMED(irq, "overflow");

        intid = tbl_msc->error_interrupt;
        flags = tbl_msc->error_interrupt_flags;
        irq = acpi_mpam_register_irq(pdev, intid, flags);
        if (irq > 0)
                res[(*res_idx)++] = DEFINE_RES_IRQ_NAMED(irq, "error");
}

static int acpi_mpam_parse_resource(struct mpam_msc *msc,
                                    struct acpi_mpam_resource_node *res)
{
        int level, nid;
        u32 cache_id;

        switch (res->locator_type) {
        case ACPI_MPAM_LOCATION_TYPE_PROCESSOR_CACHE:
                cache_id = res->locator.cache_locator.cache_reference;
                level = find_acpi_cache_level_from_id(cache_id);
                if (level <= 0) {
                        pr_err_once("Bad level (%d) for cache with id %u\n", level, cache_id);
                        return -EINVAL;
                }
                return mpam_ris_create(msc, res->ris_index, MPAM_CLASS_CACHE,
                                       level, cache_id);
        case ACPI_MPAM_LOCATION_TYPE_MEMORY:
                nid = pxm_to_node(res->locator.memory_locator.proximity_domain);
                if (nid == NUMA_NO_NODE) {
                        pr_debug("Bad proximity domain %lld, using node 0 instead\n",
                                 res->locator.memory_locator.proximity_domain);
                        nid = 0;
                }
                return mpam_ris_create(msc, res->ris_index, MPAM_CLASS_MEMORY,
                                       MPAM_CLASS_ID_DEFAULT, nid);
        default:
                /* These get discovered later and are treated as unknown */
                return 0;
        }
}

int acpi_mpam_parse_resources(struct mpam_msc *msc,
                              struct acpi_mpam_msc_node *tbl_msc)
{
        int i, err;
        char *ptr, *table_end;
        struct acpi_mpam_resource_node *resource;

        table_end = (char *)tbl_msc + tbl_msc->length;
        ptr = (char *)(tbl_msc + 1);
        for (i = 0; i < tbl_msc->num_resource_nodes; i++) {
                u64 max_deps, remaining_table;

                if (ptr + sizeof(*resource) > table_end)
                        return -EINVAL;

                resource = (struct acpi_mpam_resource_node *)ptr;

                remaining_table = table_end - ptr;
                max_deps = remaining_table / sizeof(struct acpi_mpam_func_deps);
                if (resource->num_functional_deps > max_deps) {
                        pr_debug("MSC has impossible number of functional dependencies\n");
                        return -EINVAL;
                }

                err = acpi_mpam_parse_resource(msc, resource);
                if (err)
                        return err;

                ptr += sizeof(*resource);
                ptr += resource->num_functional_deps * sizeof(struct acpi_mpam_func_deps);
        }

        return 0;
}

/*
 * Creates the device power management link and returns true if the
 * acpi id is valid and usable for cpu affinity.  This is the case
 * when the linked device is a processor or a processor container.
 */
static bool __init parse_msc_pm_link(struct acpi_mpam_msc_node *tbl_msc,
                                     struct platform_device *pdev,
                                     u32 *acpi_id)
{
        char hid[sizeof(tbl_msc->hardware_id_linked_device) + 1] = { 0 };
        bool acpi_id_valid = false;
        struct acpi_device *buddy;
        char uid[11];
        int len;

        memcpy(hid, &tbl_msc->hardware_id_linked_device,
               sizeof(tbl_msc->hardware_id_linked_device));

        if (!strcmp(hid, ACPI_PROCESSOR_CONTAINER_HID)) {
                *acpi_id = tbl_msc->instance_id_linked_device;
                acpi_id_valid = true;
        }

        len = snprintf(uid, sizeof(uid), "%u",
                       tbl_msc->instance_id_linked_device);
        if (len >= sizeof(uid)) {
                pr_debug("Failed to convert uid of device for power management.");
                return acpi_id_valid;
        }

        buddy = acpi_dev_get_first_match_dev(hid, uid, -1);
        if (buddy) {
                device_link_add(&pdev->dev, &buddy->dev, DL_FLAG_STATELESS);
                acpi_dev_put(buddy);
        }

        return acpi_id_valid;
}

static int decode_interface_type(struct acpi_mpam_msc_node *tbl_msc,
                                 enum mpam_msc_iface *iface)
{
        switch (tbl_msc->interface_type) {
        case ACPI_MPAM_MSC_IFACE_MMIO:
                *iface = MPAM_IFACE_MMIO;
                return 0;
        case ACPI_MPAM_MSC_IFACE_PCC:
                *iface = MPAM_IFACE_PCC;
                return 0;
        default:
                return -EINVAL;
        }
}

static struct platform_device * __init acpi_mpam_parse_msc(struct acpi_mpam_msc_node *tbl_msc)
{
        struct platform_device *pdev __free(platform_device_put) =
                platform_device_alloc("mpam_msc", tbl_msc->identifier);
        int next_res = 0, next_prop = 0, err;
        /* pcc, nrdy, affinity and a sentinel */
        struct property_entry props[4] = { 0 };
        /* mmio, 2xirq, no sentinel. */
        struct resource res[3] = { 0 };
        struct acpi_device *companion;
        enum mpam_msc_iface iface;
        char uid[16];
        u32 acpi_id;

        if (!pdev)
                return ERR_PTR(-ENOMEM);

        /* Some power management is described in the namespace: */
        err = snprintf(uid, sizeof(uid), "%u", tbl_msc->identifier);
        if (err > 0 && err < sizeof(uid)) {
                companion = acpi_dev_get_first_match_dev("ARMHAA5C", uid, -1);
                if (companion) {
                        ACPI_COMPANION_SET(&pdev->dev, companion);
                        acpi_dev_put(companion);
                } else {
                        pr_debug("MSC.%u: missing namespace entry\n", tbl_msc->identifier);
                }
        }

        if (decode_interface_type(tbl_msc, &iface)) {
                pr_debug("MSC.%u: unknown interface type\n", tbl_msc->identifier);
                return ERR_PTR(-EINVAL);
        }

        if (iface == MPAM_IFACE_MMIO) {
                res[next_res++] = DEFINE_RES_MEM_NAMED(tbl_msc->base_address,
                                                       tbl_msc->mmio_size,
                                                       "MPAM:MSC");
        } else if (iface == MPAM_IFACE_PCC) {
                props[next_prop++] = PROPERTY_ENTRY_U32("pcc-channel",
                                                        tbl_msc->base_address);
        }

        acpi_mpam_parse_irqs(pdev, tbl_msc, res, &next_res);

        WARN_ON_ONCE(next_res > ARRAY_SIZE(res));
        err = platform_device_add_resources(pdev, res, next_res);
        if (err)
                return ERR_PTR(err);

        props[next_prop++] = PROPERTY_ENTRY_U32("arm,not-ready-us",
                                                tbl_msc->max_nrdy_usec);

        /*
         * The MSC's CPU affinity is described via its linked power
         * management device, but only if it points at a Processor or
         * Processor Container.
         */
        if (parse_msc_pm_link(tbl_msc, pdev, &acpi_id))
                props[next_prop++] = PROPERTY_ENTRY_U32("cpu_affinity", acpi_id);

        WARN_ON_ONCE(next_prop > ARRAY_SIZE(props) - 1);
        err = device_create_managed_software_node(&pdev->dev, props, NULL);
        if (err)
                return ERR_PTR(err);

        /*
         * Stash the table entry for acpi_mpam_parse_resources() to discover
         * what this MSC controls.
         */
        err = platform_device_add_data(pdev, tbl_msc, tbl_msc->length);
        if (err)
                return ERR_PTR(err);

        err = platform_device_add(pdev);
        if (err)
                return ERR_PTR(err);

        return_ptr(pdev);
}

static int __init acpi_mpam_parse(void)
{
        char *table_end, *table_offset;
        struct acpi_mpam_msc_node *tbl_msc;
        struct platform_device *pdev;

        if (acpi_disabled || !system_supports_mpam())
                return 0;

        struct acpi_table_header *table __free(acpi_put_table) =
                acpi_get_table_pointer(ACPI_SIG_MPAM, 0);

        if (IS_ERR(table))
                return 0;

        if (table->revision < 1) {
                pr_debug("MPAM ACPI table revision %d not supported\n", table->revision);
                return 0;
        }

        table_offset = (char *)(table + 1);
        table_end = (char *)table + table->length;

        while (table_offset < table_end) {
                tbl_msc = (struct acpi_mpam_msc_node *)table_offset;
                if (table_offset + sizeof(*tbl_msc) > table_end ||
                    table_offset + tbl_msc->length > table_end) {
                        pr_err("MSC entry overlaps end of ACPI table\n");
                        return -EINVAL;
                }
                table_offset += tbl_msc->length;

                /*
                 * If any of the reserved fields are set, make no attempt to
                 * parse the MSC structure. This MSC will still be counted by
                 * acpi_mpam_count_msc(), meaning the MPAM driver can't probe
                 * against all MSC, and will never be enabled. There is no way
                 * to enable it safely, because we cannot determine safe
                 * system-wide partid and pmg ranges in this situation.
                 */
                if (tbl_msc->reserved || tbl_msc->reserved1 || tbl_msc->reserved2) {
                        pr_err_once("Unrecognised MSC, MPAM not usable\n");
                        pr_debug("MSC.%u: reserved field set\n", tbl_msc->identifier);
                        continue;
                }

                if (!tbl_msc->mmio_size) {
                        pr_debug("MSC.%u: marked as disabled\n", tbl_msc->identifier);
                        continue;
                }

                pdev = acpi_mpam_parse_msc(tbl_msc);
                if (IS_ERR(pdev))
                        return PTR_ERR(pdev);
        }

        return 0;
}

/**
 * acpi_mpam_count_msc() - Count the number of MSC described by firmware.
 *
 * Returns the number of MSCs, or zero for an error.
 *
 * This can be called before or in parallel with acpi_mpam_parse().
 */
int acpi_mpam_count_msc(void)
{
        char *table_end, *table_offset;
        struct acpi_mpam_msc_node *tbl_msc;
        int count = 0;

        if (acpi_disabled || !system_supports_mpam())
                return 0;

        struct acpi_table_header *table __free(acpi_put_table) =
                acpi_get_table_pointer(ACPI_SIG_MPAM, 0);

        if (IS_ERR(table))
                return 0;

        if (table->revision < 1)
                return 0;

        table_offset = (char *)(table + 1);
        table_end = (char *)table + table->length;

        while (table_offset < table_end) {
                tbl_msc = (struct acpi_mpam_msc_node *)table_offset;

                if (table_offset + sizeof(*tbl_msc) > table_end)
                        return -EINVAL;
                if (tbl_msc->length < sizeof(*tbl_msc))
                        return -EINVAL;
                if (tbl_msc->length > table_end - table_offset)
                        return -EINVAL;
                table_offset += tbl_msc->length;

                if (!tbl_msc->mmio_size)
                        continue;

                count++;
        }

        return count;
}

/*
 * Call after ACPI devices have been created, which happens behind acpi_scan_init()
 * called from subsys_initcall(). PCC requires the mailbox driver, which is
 * initialised from postcore_initcall().
 */
subsys_initcall_sync(acpi_mpam_parse);