/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/hyperv.h>
#include <linux/version.h>
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <asm/hyperv.h>
#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"

/* The one and only */
struct hv_context hv_context = {
        .synic_initialized      = false,
        .hypercall_page         = NULL,
};

#define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
#define HV_MIN_DELTA_TICKS 1

/*
 * query_hypervisor_info - Get version info of the windows hypervisor
 */
unsigned int host_info_eax;
unsigned int host_info_ebx;
unsigned int host_info_ecx;
unsigned int host_info_edx;

static int query_hypervisor_info(void)
{
        unsigned int eax;
        unsigned int ebx;
        unsigned int ecx;
        unsigned int edx;
        unsigned int max_leaf;
        unsigned int op;

        /*
        * Its assumed that this is called after confirming that Viridian
        * is present. Query id and revision.
        */
        eax = 0;
        ebx = 0;
        ecx = 0;
        edx = 0;
        op = HVCPUID_VENDOR_MAXFUNCTION;
        cpuid(op, &eax, &ebx, &ecx, &edx);

        max_leaf = eax;

        if (max_leaf >= HVCPUID_VERSION) {
                eax = 0;
                ebx = 0;
                ecx = 0;
                edx = 0;
                op = HVCPUID_VERSION;
                cpuid(op, &eax, &ebx, &ecx, &edx);
                host_info_eax = eax;
                host_info_ebx = ebx;
                host_info_ecx = ecx;
                host_info_edx = edx;
        }
        return max_leaf;
}

/*
 * do_hypercall- Invoke the specified hypercall
 */
static u64 do_hypercall(u64 control, void *input, void *output)
{
#ifdef CONFIG_X86_64
        u64 hv_status = 0;
        u64 input_address = (input) ? virt_to_phys(input) : 0;
        u64 output_address = (output) ? virt_to_phys(output) : 0;
        void *hypercall_page = hv_context.hypercall_page;

        __asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");
        __asm__ __volatile__("call *%3" : "=a" (hv_status) :
                             "c" (control), "d" (input_address),
                             "m" (hypercall_page));

        return hv_status;

#else

        u32 control_hi = control >> 32;
        u32 control_lo = control & 0xFFFFFFFF;
        u32 hv_status_hi = 1;
        u32 hv_status_lo = 1;
        u64 input_address = (input) ? virt_to_phys(input) : 0;
        u32 input_address_hi = input_address >> 32;
        u32 input_address_lo = input_address & 0xFFFFFFFF;
        u64 output_address = (output) ? virt_to_phys(output) : 0;
        u32 output_address_hi = output_address >> 32;
        u32 output_address_lo = output_address & 0xFFFFFFFF;
        void *hypercall_page = hv_context.hypercall_page;

        __asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi),
                              "=a"(hv_status_lo) : "d" (control_hi),
                              "a" (control_lo), "b" (input_address_hi),
                              "c" (input_address_lo), "D"(output_address_hi),
                              "S"(output_address_lo), "m" (hypercall_page));

        return hv_status_lo | ((u64)hv_status_hi << 32);
#endif /* !x86_64 */
}

/*
 * hv_init - Main initialization routine.
 *
 * This routine must be called before any other routines in here are called
 */
int hv_init(void)
{
        int max_leaf;
        union hv_x64_msr_hypercall_contents hypercall_msr;
        void *virtaddr = NULL;

        memset(hv_context.synic_event_page, 0, sizeof(void *) * NR_CPUS);
        memset(hv_context.synic_message_page, 0,
               sizeof(void *) * NR_CPUS);
        memset(hv_context.post_msg_page, 0,
               sizeof(void *) * NR_CPUS);
        memset(hv_context.vp_index, 0,
               sizeof(int) * NR_CPUS);
        memset(hv_context.event_dpc, 0,
               sizeof(void *) * NR_CPUS);
        memset(hv_context.clk_evt, 0,
               sizeof(void *) * NR_CPUS);

        max_leaf = query_hypervisor_info();

        /*
         * Write our OS ID.
         */
        hv_context.guestid = generate_guest_id(0, LINUX_VERSION_CODE, 0);
        wrmsrl(HV_X64_MSR_GUEST_OS_ID, hv_context.guestid);

        /* See if the hypercall page is already set */
        rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

        virtaddr = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_EXEC);

        if (!virtaddr)
                goto cleanup;

        hypercall_msr.enable = 1;

        hypercall_msr.guest_physical_address = vmalloc_to_pfn(virtaddr);
        wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

        /* Confirm that hypercall page did get setup. */
        hypercall_msr.as_uint64 = 0;
        rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

        if (!hypercall_msr.enable)
                goto cleanup;

        hv_context.hypercall_page = virtaddr;

        return 0;

cleanup:
        if (virtaddr) {
                if (hypercall_msr.enable) {
                        hypercall_msr.as_uint64 = 0;
                        wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
                }

                vfree(virtaddr);
        }

        return -ENOTSUPP;
}

/*
 * hv_cleanup - Cleanup routine.
 *
 * This routine is called normally during driver unloading or exiting.
 */
void hv_cleanup(void)
{
        union hv_x64_msr_hypercall_contents hypercall_msr;

        /* Reset our OS id */
        wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);

        if (hv_context.hypercall_page) {
                hypercall_msr.as_uint64 = 0;
                wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
                vfree(hv_context.hypercall_page);
                hv_context.hypercall_page = NULL;
        }
}

/*
 * hv_post_message - Post a message using the hypervisor message IPC.
 *
 * This involves a hypercall.
 */
int hv_post_message(union hv_connection_id connection_id,
                  enum hv_message_type message_type,
                  void *payload, size_t payload_size)
{

        struct hv_input_post_message *aligned_msg;
        u16 status;

        if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
                return -EMSGSIZE;

        aligned_msg = (struct hv_input_post_message *)
                        hv_context.post_msg_page[get_cpu()];

        aligned_msg->connectionid = connection_id;
        aligned_msg->reserved = 0;
        aligned_msg->message_type = message_type;
        aligned_msg->payload_size = payload_size;
        memcpy((void *)aligned_msg->payload, payload, payload_size);

        status = do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL)
                & 0xFFFF;

        put_cpu();
        return status;
}


/*
 * hv_signal_event -
 * Signal an event on the specified connection using the hypervisor event IPC.
 *
 * This involves a hypercall.
 */
u16 hv_signal_event(void *con_id)
{
        u16 status;

        status = (do_hypercall(HVCALL_SIGNAL_EVENT, con_id, NULL) & 0xFFFF);

        return status;
}

static int hv_ce_set_next_event(unsigned long delta,
                                struct clock_event_device *evt)
{
        cycle_t current_tick;

        WARN_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT);

        rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
        current_tick += delta;
        wrmsrl(HV_X64_MSR_STIMER0_COUNT, current_tick);
        return 0;
}

static void hv_ce_setmode(enum clock_event_mode mode,
                          struct clock_event_device *evt)
{
        union hv_timer_config timer_cfg;

        switch (mode) {
        case CLOCK_EVT_MODE_PERIODIC:
                /* unsupported */
                break;

        case CLOCK_EVT_MODE_ONESHOT:
                timer_cfg.enable = 1;
                timer_cfg.auto_enable = 1;
                timer_cfg.sintx = VMBUS_MESSAGE_SINT;
                wrmsrl(HV_X64_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
                break;

        case CLOCK_EVT_MODE_UNUSED:
        case CLOCK_EVT_MODE_SHUTDOWN:
                wrmsrl(HV_X64_MSR_STIMER0_COUNT, 0);
                wrmsrl(HV_X64_MSR_STIMER0_CONFIG, 0);
                break;
        case CLOCK_EVT_MODE_RESUME:
                break;
        }
}

static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
{
        dev->name = "Hyper-V clockevent";
        dev->features = CLOCK_EVT_FEAT_ONESHOT;
        dev->cpumask = cpumask_of(cpu);
        dev->rating = 1000;
        /*
         * Avoid settint dev->owner = THIS_MODULE deliberately as doing so will
         * result in clockevents_config_and_register() taking additional
         * references to the hv_vmbus module making it impossible to unload.
         */

        dev->set_mode = hv_ce_setmode;
        dev->set_next_event = hv_ce_set_next_event;
}


int hv_synic_alloc(void)
{
        size_t size = sizeof(struct tasklet_struct);
        size_t ced_size = sizeof(struct clock_event_device);
        int cpu;

        for_each_online_cpu(cpu) {
                hv_context.event_dpc[cpu] = kmalloc(size, GFP_ATOMIC);
                if (hv_context.event_dpc[cpu] == NULL) {
                        pr_err("Unable to allocate event dpc\n");
                        goto err;
                }
                tasklet_init(hv_context.event_dpc[cpu], vmbus_on_event, cpu);

                hv_context.clk_evt[cpu] = kzalloc(ced_size, GFP_ATOMIC);
                if (hv_context.clk_evt[cpu] == NULL) {
                        pr_err("Unable to allocate clock event device\n");
                        goto err;
                }
                hv_init_clockevent_device(hv_context.clk_evt[cpu], cpu);

                hv_context.synic_message_page[cpu] =
                        (void *)get_zeroed_page(GFP_ATOMIC);

                if (hv_context.synic_message_page[cpu] == NULL) {
                        pr_err("Unable to allocate SYNIC message page\n");
                        goto err;
                }

                hv_context.synic_event_page[cpu] =
                        (void *)get_zeroed_page(GFP_ATOMIC);

                if (hv_context.synic_event_page[cpu] == NULL) {
                        pr_err("Unable to allocate SYNIC event page\n");
                        goto err;
                }

                hv_context.post_msg_page[cpu] =
                        (void *)get_zeroed_page(GFP_ATOMIC);

                if (hv_context.post_msg_page[cpu] == NULL) {
                        pr_err("Unable to allocate post msg page\n");
                        goto err;
                }
        }

        return 0;
err:
        return -ENOMEM;
}

static void hv_synic_free_cpu(int cpu)
{
        kfree(hv_context.event_dpc[cpu]);
        kfree(hv_context.clk_evt[cpu]);
        if (hv_context.synic_event_page[cpu])
                free_page((unsigned long)hv_context.synic_event_page[cpu]);
        if (hv_context.synic_message_page[cpu])
                free_page((unsigned long)hv_context.synic_message_page[cpu]);
        if (hv_context.post_msg_page[cpu])
                free_page((unsigned long)hv_context.post_msg_page[cpu]);
}

void hv_synic_free(void)
{
        int cpu;

        for_each_online_cpu(cpu)
                hv_synic_free_cpu(cpu);
}

/*
 * hv_synic_init - Initialize the Synthethic Interrupt Controller.
 *
 * If it is already initialized by another entity (ie x2v shim), we need to
 * retrieve the initialized message and event pages.  Otherwise, we create and
 * initialize the message and event pages.
 */
void hv_synic_init(void *arg)
{
        u64 version;
        union hv_synic_simp simp;
        union hv_synic_siefp siefp;
        union hv_synic_sint shared_sint;
        union hv_synic_scontrol sctrl;
        u64 vp_index;

        int cpu = smp_processor_id();

        if (!hv_context.hypercall_page)
                return;

        /* Check the version */
        rdmsrl(HV_X64_MSR_SVERSION, version);

        /* Setup the Synic's message page */
        rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
        simp.simp_enabled = 1;
        simp.base_simp_gpa = virt_to_phys(hv_context.synic_message_page[cpu])
                >> PAGE_SHIFT;

        wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);

        /* Setup the Synic's event page */
        rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
        siefp.siefp_enabled = 1;
        siefp.base_siefp_gpa = virt_to_phys(hv_context.synic_event_page[cpu])
                >> PAGE_SHIFT;

        wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);

        /* Setup the shared SINT. */
        rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

        shared_sint.as_uint64 = 0;
        shared_sint.vector = HYPERVISOR_CALLBACK_VECTOR;
        shared_sint.masked = false;
        shared_sint.auto_eoi = true;

        wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

        /* Enable the global synic bit */
        rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
        sctrl.enable = 1;

        wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);

        hv_context.synic_initialized = true;

        /*
         * Setup the mapping between Hyper-V's notion
         * of cpuid and Linux' notion of cpuid.
         * This array will be indexed using Linux cpuid.
         */
        rdmsrl(HV_X64_MSR_VP_INDEX, vp_index);
        hv_context.vp_index[cpu] = (u32)vp_index;

        INIT_LIST_HEAD(&hv_context.percpu_list[cpu]);

        /*
         * Register the per-cpu clockevent source.
         */
        if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
                clockevents_config_and_register(hv_context.clk_evt[cpu],
                                                HV_TIMER_FREQUENCY,
                                                HV_MIN_DELTA_TICKS,
                                                HV_MAX_MAX_DELTA_TICKS);
        return;
}

/*
 * hv_synic_clockevents_cleanup - Cleanup clockevent devices
 */
void hv_synic_clockevents_cleanup(void)
{
        int cpu;

        if (!(ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE))
                return;

        for_each_online_cpu(cpu)
                clockevents_unbind_device(hv_context.clk_evt[cpu], cpu);
}

/*
 * hv_synic_cleanup - Cleanup routine for hv_synic_init().
 */
void hv_synic_cleanup(void *arg)
{
        union hv_synic_sint shared_sint;
        union hv_synic_simp simp;
        union hv_synic_siefp siefp;
        union hv_synic_scontrol sctrl;
        int cpu = smp_processor_id();

        if (!hv_context.synic_initialized)
                return;

        /* Turn off clockevent device */
        if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
                hv_ce_setmode(CLOCK_EVT_MODE_SHUTDOWN,
                              hv_context.clk_evt[cpu]);

        rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

        shared_sint.masked = 1;

        /* Need to correctly cleanup in the case of SMP!!! */
        /* Disable the interrupt */
        wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

        rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
        simp.simp_enabled = 0;
        simp.base_simp_gpa = 0;

        wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);

        rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
        siefp.siefp_enabled = 0;
        siefp.base_siefp_gpa = 0;

        wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);

        /* Disable the global synic bit */
        rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
        sctrl.enable = 0;
        wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);

        hv_synic_free_cpu(cpu);
}