/*
 * Copyright 2012 by Oracle Inc
 * Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
 *
 * This code borrows ideas from https://lkml.org/lkml/2011/11/30/249
 * so many thanks go to Kevin Tian <kevin.tian@intel.com>
 * and Yu Ke <ke.yu@intel.com>.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/cpumask.h>
#include <linux/cpufreq.h>
#include <linux/freezer.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/acpi.h>
#include <acpi/processor.h>
#include <xen/xen.h>
#include <xen/xen-ops.h>
#include <xen/interface/platform.h>
#include <asm/xen/hypercall.h>

static int no_hypercall;
MODULE_PARM_DESC(off, "Inhibit the hypercall.");
module_param_named(off, no_hypercall, int, 0400);

/*
 * Note: Do not convert the acpi_id* below to cpumask_var_t or use cpumask_bit
 * - as those shrink to nr_cpu_bits (which is dependent on possible_cpu), which
 * can be less than what we want to put in. Instead use the 'nr_acpi_bits'
 * which is dynamically computed based on the MADT or x2APIC table.
 */
static unsigned int nr_acpi_bits;
/* Mutex to protect the acpi_ids_done - for CPU hotplug use. */
static DEFINE_MUTEX(acpi_ids_mutex);
/* Which ACPI ID we have processed from 'struct acpi_processor'. */
static unsigned long *acpi_ids_done;
/* Which ACPI ID exist in the SSDT/DSDT processor definitions. */
static unsigned long *acpi_id_present;
/* And if there is an _CST definition (or a PBLK) for the ACPI IDs */
static unsigned long *acpi_id_cst_present;

static int push_cxx_to_hypervisor(struct acpi_processor *_pr)
{
        struct xen_platform_op op = {
                .cmd                    = XENPF_set_processor_pminfo,
                .interface_version      = XENPF_INTERFACE_VERSION,
                .u.set_pminfo.id        = _pr->acpi_id,
                .u.set_pminfo.type      = XEN_PM_CX,
        };
        struct xen_processor_cx *dst_cx, *dst_cx_states = NULL;
        struct acpi_processor_cx *cx;
        unsigned int i, ok;
        int ret = 0;

        dst_cx_states = kcalloc(_pr->power.count,
                                sizeof(struct xen_processor_cx), GFP_KERNEL);
        if (!dst_cx_states)
                return -ENOMEM;

        for (ok = 0, i = 1; i <= _pr->power.count; i++) {
                cx = &_pr->power.states[i];
                if (!cx->valid)
                        continue;

                dst_cx = &(dst_cx_states[ok++]);

                dst_cx->reg.space_id = ACPI_ADR_SPACE_SYSTEM_IO;
                if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
                        dst_cx->reg.bit_width = 8;
                        dst_cx->reg.bit_offset = 0;
                        dst_cx->reg.access_size = 1;
                } else {
                        dst_cx->reg.space_id = ACPI_ADR_SPACE_FIXED_HARDWARE;
                        if (cx->entry_method == ACPI_CSTATE_FFH) {
                                /* NATIVE_CSTATE_BEYOND_HALT */
                                dst_cx->reg.bit_offset = 2;
                                dst_cx->reg.bit_width = 1; /* VENDOR_INTEL */
                        }
                        dst_cx->reg.access_size = 0;
                }
                dst_cx->reg.address = cx->address;

                dst_cx->type = cx->type;
                dst_cx->latency = cx->latency;

                dst_cx->dpcnt = 0;
                set_xen_guest_handle(dst_cx->dp, NULL);
        }
        if (!ok) {
                pr_debug("No _Cx for ACPI CPU %u\n", _pr->acpi_id);
                kfree(dst_cx_states);
                return -EINVAL;
        }
        op.u.set_pminfo.power.count = ok;
        op.u.set_pminfo.power.flags.bm_control = _pr->flags.bm_control;
        op.u.set_pminfo.power.flags.bm_check = _pr->flags.bm_check;
        op.u.set_pminfo.power.flags.has_cst = _pr->flags.has_cst;
        op.u.set_pminfo.power.flags.power_setup_done =
                _pr->flags.power_setup_done;

        set_xen_guest_handle(op.u.set_pminfo.power.states, dst_cx_states);

        if (!no_hypercall)
                ret = HYPERVISOR_platform_op(&op);

        if (!ret) {
                pr_debug("ACPI CPU%u - C-states uploaded.\n", _pr->acpi_id);
                for (i = 1; i <= _pr->power.count; i++) {
                        cx = &_pr->power.states[i];
                        if (!cx->valid)
                                continue;
                        pr_debug("     C%d: %s %d uS\n",
                                 cx->type, cx->desc, (u32)cx->latency);
                }
        } else if ((ret != -EINVAL) && (ret != -ENOSYS))
                /* EINVAL means the ACPI ID is incorrect - meaning the ACPI
                 * table is referencing a non-existing CPU - which can happen
                 * with broken ACPI tables. */
                pr_err("(CX): Hypervisor error (%d) for ACPI CPU%u\n",
                       ret, _pr->acpi_id);

        kfree(dst_cx_states);

        return ret;
}
static struct xen_processor_px *
xen_copy_pss_data(struct acpi_processor *_pr,
                  struct xen_processor_performance *dst_perf)
{
        struct xen_processor_px *dst_states = NULL;
        unsigned int i;

        BUILD_BUG_ON(sizeof(struct xen_processor_px) !=
                     sizeof(struct acpi_processor_px));

        dst_states = kcalloc(_pr->performance->state_count,
                             sizeof(struct xen_processor_px), GFP_KERNEL);
        if (!dst_states)
                return ERR_PTR(-ENOMEM);

        dst_perf->state_count = _pr->performance->state_count;
        for (i = 0; i < _pr->performance->state_count; i++) {
                /* Fortunatly for us, they are both the same size */
                memcpy(&(dst_states[i]), &(_pr->performance->states[i]),
                       sizeof(struct acpi_processor_px));
        }
        return dst_states;
}
static int xen_copy_psd_data(struct acpi_processor *_pr,
                             struct xen_processor_performance *dst)
{
        struct acpi_psd_package *pdomain;

        BUILD_BUG_ON(sizeof(struct xen_psd_package) !=
                     sizeof(struct acpi_psd_package));

        /* This information is enumerated only if acpi_processor_preregister_performance
         * has been called.
         */
        dst->shared_type = _pr->performance->shared_type;

        pdomain = &(_pr->performance->domain_info);

        /* 'acpi_processor_preregister_performance' does not parse if the
         * num_processors <= 1, but Xen still requires it. Do it manually here.
         */
        if (pdomain->num_processors <= 1) {
                if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
                        dst->shared_type = CPUFREQ_SHARED_TYPE_ALL;
                else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
                        dst->shared_type = CPUFREQ_SHARED_TYPE_HW;
                else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
                        dst->shared_type = CPUFREQ_SHARED_TYPE_ANY;

        }
        memcpy(&(dst->domain_info), pdomain, sizeof(struct acpi_psd_package));
        return 0;
}
static int xen_copy_pct_data(struct acpi_pct_register *pct,
                             struct xen_pct_register *dst_pct)
{
        /* It would be nice if you could just do 'memcpy(pct, dst_pct') but
         * sadly the Xen structure did not have the proper padding so the
         * descriptor field takes two (dst_pct) bytes instead of one (pct).
         */
        dst_pct->descriptor = pct->descriptor;
        dst_pct->length = pct->length;
        dst_pct->space_id = pct->space_id;
        dst_pct->bit_width = pct->bit_width;
        dst_pct->bit_offset = pct->bit_offset;
        dst_pct->reserved = pct->reserved;
        dst_pct->address = pct->address;
        return 0;
}
static int push_pxx_to_hypervisor(struct acpi_processor *_pr)
{
        int ret = 0;
        struct xen_platform_op op = {
                .cmd                    = XENPF_set_processor_pminfo,
                .interface_version      = XENPF_INTERFACE_VERSION,
                .u.set_pminfo.id        = _pr->acpi_id,
                .u.set_pminfo.type      = XEN_PM_PX,
        };
        struct xen_processor_performance *dst_perf;
        struct xen_processor_px *dst_states = NULL;

        dst_perf = &op.u.set_pminfo.perf;

        dst_perf->platform_limit = _pr->performance_platform_limit;
        dst_perf->flags |= XEN_PX_PPC;
        xen_copy_pct_data(&(_pr->performance->control_register),
                          &dst_perf->control_register);
        xen_copy_pct_data(&(_pr->performance->status_register),
                          &dst_perf->status_register);
        dst_perf->flags |= XEN_PX_PCT;
        dst_states = xen_copy_pss_data(_pr, dst_perf);
        if (!IS_ERR_OR_NULL(dst_states)) {
                set_xen_guest_handle(dst_perf->states, dst_states);
                dst_perf->flags |= XEN_PX_PSS;
        }
        if (!xen_copy_psd_data(_pr, dst_perf))
                dst_perf->flags |= XEN_PX_PSD;

        if (dst_perf->flags != (XEN_PX_PSD | XEN_PX_PSS | XEN_PX_PCT | XEN_PX_PPC)) {
                pr_warn("ACPI CPU%u missing some P-state data (%x), skipping\n",
                        _pr->acpi_id, dst_perf->flags);
                ret = -ENODEV;
                goto err_free;
        }

        if (!no_hypercall)
                ret = HYPERVISOR_platform_op(&op);

        if (!ret) {
                struct acpi_processor_performance *perf;
                unsigned int i;

                perf = _pr->performance;
                pr_debug("ACPI CPU%u - P-states uploaded.\n", _pr->acpi_id);
                for (i = 0; i < perf->state_count; i++) {
                        pr_debug("     %cP%d: %d MHz, %d mW, %d uS\n",
                        (i == perf->state ? '*' : ' '), i,
                        (u32) perf->states[i].core_frequency,
                        (u32) perf->states[i].power,
                        (u32) perf->states[i].transition_latency);
                }
        } else if ((ret != -EINVAL) && (ret != -ENOSYS))
                /* EINVAL means the ACPI ID is incorrect - meaning the ACPI
                 * table is referencing a non-existing CPU - which can happen
                 * with broken ACPI tables. */
                pr_warn("(_PXX): Hypervisor error (%d) for ACPI CPU%u\n",
                        ret, _pr->acpi_id);
err_free:
        if (!IS_ERR_OR_NULL(dst_states))
                kfree(dst_states);

        return ret;
}
static int upload_pm_data(struct acpi_processor *_pr)
{
        int err = 0;

        mutex_lock(&acpi_ids_mutex);
        if (__test_and_set_bit(_pr->acpi_id, acpi_ids_done)) {
                mutex_unlock(&acpi_ids_mutex);
                return -EBUSY;
        }
        if (_pr->flags.power)
                err = push_cxx_to_hypervisor(_pr);

        if (_pr->performance && _pr->performance->states)
                err |= push_pxx_to_hypervisor(_pr);

        mutex_unlock(&acpi_ids_mutex);
        return err;
}
static unsigned int __init get_max_acpi_id(void)
{
        struct xenpf_pcpuinfo *info;
        struct xen_platform_op op = {
                .cmd = XENPF_get_cpuinfo,
                .interface_version = XENPF_INTERFACE_VERSION,
        };
        int ret = 0;
        unsigned int i, last_cpu, max_acpi_id = 0;

        info = &op.u.pcpu_info;
        info->xen_cpuid = 0;

        ret = HYPERVISOR_platform_op(&op);
        if (ret)
                return NR_CPUS;

        /* The max_present is the same irregardless of the xen_cpuid */
        last_cpu = op.u.pcpu_info.max_present;
        for (i = 0; i <= last_cpu; i++) {
                info->xen_cpuid = i;
                ret = HYPERVISOR_platform_op(&op);
                if (ret)
                        continue;
                max_acpi_id = max(info->acpi_id, max_acpi_id);
        }
        max_acpi_id *= 2; /* Slack for CPU hotplug support. */
        pr_debug("Max ACPI ID: %u\n", max_acpi_id);
        return max_acpi_id;
}
/*
 * The read_acpi_id and check_acpi_ids are there to support the Xen
 * oddity of virtual CPUs != physical CPUs in the initial domain.
 * The user can supply 'xen_max_vcpus=X' on the Xen hypervisor line
 * which will band the amount of CPUs the initial domain can see.
 * In general that is OK, except it plays havoc with any of the
 * for_each_[present|online]_cpu macros which are banded to the virtual
 * CPU amount.
 */
static acpi_status
read_acpi_id(acpi_handle handle, u32 lvl, void *context, void **rv)
{
        u32 acpi_id;
        acpi_status status;
        acpi_object_type acpi_type;
        unsigned long long tmp;
        union acpi_object object = { 0 };
        struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
        acpi_io_address pblk = 0;

        status = acpi_get_type(handle, &acpi_type);
        if (ACPI_FAILURE(status))
                return AE_OK;

        switch (acpi_type) {
        case ACPI_TYPE_PROCESSOR:
                status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
                if (ACPI_FAILURE(status))
                        return AE_OK;
                acpi_id = object.processor.proc_id;
                pblk = object.processor.pblk_address;
                break;
        case ACPI_TYPE_DEVICE:
                status = acpi_evaluate_integer(handle, "_UID", NULL, &tmp);
                if (ACPI_FAILURE(status))
                        return AE_OK;
                acpi_id = tmp;
                break;
        default:
                return AE_OK;
        }
        /* There are more ACPI Processor objects than in x2APIC or MADT.
         * This can happen with incorrect ACPI SSDT declerations. */
        if (acpi_id > nr_acpi_bits) {
                pr_debug("We only have %u, trying to set %u\n",
                         nr_acpi_bits, acpi_id);
                return AE_OK;
        }
        /* OK, There is a ACPI Processor object */
        __set_bit(acpi_id, acpi_id_present);

        pr_debug("ACPI CPU%u w/ PBLK:0x%lx\n", acpi_id, (unsigned long)pblk);

        status = acpi_evaluate_object(handle, "_CST", NULL, &buffer);
        if (ACPI_FAILURE(status)) {
                if (!pblk)
                        return AE_OK;
        }
        /* .. and it has a C-state */
        __set_bit(acpi_id, acpi_id_cst_present);

        return AE_OK;
}
static int check_acpi_ids(struct acpi_processor *pr_backup)
{

        if (!pr_backup)
                return -ENODEV;

        if (acpi_id_present && acpi_id_cst_present)
                /* OK, done this once .. skip to uploading */
                goto upload;

        /* All online CPUs have been processed at this stage. Now verify
         * whether in fact "online CPUs" == physical CPUs.
         */
        acpi_id_present = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
        if (!acpi_id_present)
                return -ENOMEM;

        acpi_id_cst_present = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
        if (!acpi_id_cst_present) {
                kfree(acpi_id_present);
                return -ENOMEM;
        }

        acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
                            ACPI_UINT32_MAX,
                            read_acpi_id, NULL, NULL, NULL);
        acpi_get_devices("ACPI0007", read_acpi_id, NULL, NULL);

upload:
        if (!bitmap_equal(acpi_id_present, acpi_ids_done, nr_acpi_bits)) {
                unsigned int i;
                for_each_set_bit(i, acpi_id_present, nr_acpi_bits) {
                        pr_backup->acpi_id = i;
                        /* Mask out C-states if there are no _CST or PBLK */
                        pr_backup->flags.power = test_bit(i, acpi_id_cst_present);
                        (void)upload_pm_data(pr_backup);
                }
        }

        return 0;
}

/* acpi_perf_data is a pointer to percpu data. */
static struct acpi_processor_performance __percpu *acpi_perf_data;

static void free_acpi_perf_data(void)
{
        unsigned int i;

        /* Freeing a NULL pointer is OK, and alloc_percpu zeroes. */
        for_each_possible_cpu(i)
                free_cpumask_var(per_cpu_ptr(acpi_perf_data, i)
                                 ->shared_cpu_map);
        free_percpu(acpi_perf_data);
}

static int xen_upload_processor_pm_data(void)
{
        struct acpi_processor *pr_backup = NULL;
        unsigned int i;
        int rc = 0;

        pr_info("Uploading Xen processor PM info\n");

        for_each_possible_cpu(i) {
                struct acpi_processor *_pr;
                _pr = per_cpu(processors, i /* APIC ID */);
                if (!_pr)
                        continue;

                if (!pr_backup) {
                        pr_backup = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
                        if (pr_backup)
                                memcpy(pr_backup, _pr, sizeof(struct acpi_processor));
                }
                (void)upload_pm_data(_pr);
        }

        rc = check_acpi_ids(pr_backup);
        kfree(pr_backup);

        return rc;
}

static int xen_acpi_processor_resume(struct notifier_block *nb,
                                     unsigned long action, void *data)
{
        bitmap_zero(acpi_ids_done, nr_acpi_bits);
        return xen_upload_processor_pm_data();
}

struct notifier_block xen_acpi_processor_resume_nb = {
        .notifier_call = xen_acpi_processor_resume,
};

static int __init xen_acpi_processor_init(void)
{
        unsigned int i;
        int rc;

        if (!xen_initial_domain())
                return -ENODEV;

        nr_acpi_bits = get_max_acpi_id() + 1;
        acpi_ids_done = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
        if (!acpi_ids_done)
                return -ENOMEM;

        acpi_perf_data = alloc_percpu(struct acpi_processor_performance);
        if (!acpi_perf_data) {
                pr_debug("Memory allocation error for acpi_perf_data\n");
                kfree(acpi_ids_done);
                return -ENOMEM;
        }
        for_each_possible_cpu(i) {
                if (!zalloc_cpumask_var_node(
                        &per_cpu_ptr(acpi_perf_data, i)->shared_cpu_map,
                        GFP_KERNEL, cpu_to_node(i))) {
                        rc = -ENOMEM;
                        goto err_out;
                }
        }

        /* Do initialization in ACPI core. It is OK to fail here. */
        (void)acpi_processor_preregister_performance(acpi_perf_data);

        for_each_possible_cpu(i) {
                struct acpi_processor *pr;
                struct acpi_processor_performance *perf;

                pr = per_cpu(processors, i);
                perf = per_cpu_ptr(acpi_perf_data, i);
                if (!pr)
                        continue;

                pr->performance = perf;
                rc = acpi_processor_get_performance_info(pr);
                if (rc)
                        goto err_out;
        }

        rc = xen_upload_processor_pm_data();
        if (rc)
                goto err_unregister;

        xen_resume_notifier_register(&xen_acpi_processor_resume_nb);

        return 0;
err_unregister:
        for_each_possible_cpu(i)
                acpi_processor_unregister_performance(i);

err_out:
        /* Freeing a NULL pointer is OK: alloc_percpu zeroes. */
        free_acpi_perf_data();
        kfree(acpi_ids_done);
        return rc;
}
static void __exit xen_acpi_processor_exit(void)
{
        int i;

        xen_resume_notifier_unregister(&xen_acpi_processor_resume_nb);
        kfree(acpi_ids_done);
        kfree(acpi_id_present);
        kfree(acpi_id_cst_present);
        for_each_possible_cpu(i)
                acpi_processor_unregister_performance(i);

        free_acpi_perf_data();
}

MODULE_AUTHOR("Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>");
MODULE_DESCRIPTION("Xen ACPI Processor P-states (and Cx) driver which uploads PM data to Xen hypervisor");
MODULE_LICENSE("GPL");

/* We want to be loaded before the CPU freq scaling drivers are loaded.
 * They are loaded in late_initcall. */
device_initcall(xen_acpi_processor_init);
module_exit(xen_acpi_processor_exit);