/*
 * Copyright (C) 2015 Google, Inc
 *
 * SPDX-License-Identifier:     GPL-2.0+
 *
 * Based on code from the coreboot file of the same name
 */

#include <common.h>
#include <cpu.h>
#include <dm.h>
#include <errno.h>
#include <malloc.h>
#include <asm/atomic.h>
#include <asm/cpu.h>
#include <asm/interrupt.h>
#include <asm/lapic.h>
#include <asm/mp.h>
#include <asm/msr.h>
#include <asm/mtrr.h>
#include <asm/processor.h>
#include <asm/sipi.h>
#include <dm/device-internal.h>
#include <dm/uclass-internal.h>
#include <linux/linkage.h>

DECLARE_GLOBAL_DATA_PTR;

/* Total CPUs include BSP */
static int num_cpus;

/* This also needs to match the sipi.S assembly code for saved MSR encoding */
struct saved_msr {
        uint32_t index;
        uint32_t lo;
        uint32_t hi;
} __packed;


struct mp_flight_plan {
        int num_records;
        struct mp_flight_record *records;
};

static struct mp_flight_plan mp_info;

struct cpu_map {
        struct udevice *dev;
        int apic_id;
        int err_code;
};

static inline void barrier_wait(atomic_t *b)
{
        while (atomic_read(b) == 0)
                asm("pause");
        mfence();
}

static inline void release_barrier(atomic_t *b)
{
        mfence();
        atomic_set(b, 1);
}

static inline void stop_this_cpu(void)
{
        /* Called by an AP when it is ready to halt and wait for a new task */
        for (;;)
                cpu_hlt();
}

/* Returns 1 if timeout waiting for APs. 0 if target APs found */
static int wait_for_aps(atomic_t *val, int target, int total_delay,
                        int delay_step)
{
        int timeout = 0;
        int delayed = 0;

        while (atomic_read(val) != target) {
                udelay(delay_step);
                delayed += delay_step;
                if (delayed >= total_delay) {
                        timeout = 1;
                        break;
                }
        }

        return timeout;
}

static void ap_do_flight_plan(struct udevice *cpu)
{
        int i;

        for (i = 0; i < mp_info.num_records; i++) {
                struct mp_flight_record *rec = &mp_info.records[i];

                atomic_inc(&rec->cpus_entered);
                barrier_wait(&rec->barrier);

                if (rec->ap_call != NULL)
                        rec->ap_call(cpu, rec->ap_arg);
        }
}

static int find_cpu_by_apid_id(int apic_id, struct udevice **devp)
{
        struct udevice *dev;

        *devp = NULL;
        for (uclass_find_first_device(UCLASS_CPU, &dev);
             dev;
             uclass_find_next_device(&dev)) {
                struct cpu_platdata *plat = dev_get_parent_platdata(dev);

                if (plat->cpu_id == apic_id) {
                        *devp = dev;
                        return 0;
                }
        }

        return -ENOENT;
}

/*
 * By the time APs call ap_init() caching has been setup, and microcode has
 * been loaded
 */
static void ap_init(unsigned int cpu_index)
{
        struct udevice *dev;
        int apic_id;
        int ret;

        /* Ensure the local apic is enabled */
        enable_lapic();

        apic_id = lapicid();
        ret = find_cpu_by_apid_id(apic_id, &dev);
        if (ret) {
                debug("Unknown CPU apic_id %x\n", apic_id);
                goto done;
        }

        debug("AP: slot %d apic_id %x, dev %s\n", cpu_index, apic_id,
              dev ? dev->name : "(apic_id not found)");

        /* Walk the flight plan */
        ap_do_flight_plan(dev);

        /* Park the AP */
        debug("parking\n");
done:
        stop_this_cpu();
}

static const unsigned int fixed_mtrrs[NUM_FIXED_MTRRS] = {
        MTRR_FIX_64K_00000_MSR, MTRR_FIX_16K_80000_MSR, MTRR_FIX_16K_A0000_MSR,
        MTRR_FIX_4K_C0000_MSR, MTRR_FIX_4K_C8000_MSR, MTRR_FIX_4K_D0000_MSR,
        MTRR_FIX_4K_D8000_MSR, MTRR_FIX_4K_E0000_MSR, MTRR_FIX_4K_E8000_MSR,
        MTRR_FIX_4K_F0000_MSR, MTRR_FIX_4K_F8000_MSR,
};

static inline struct saved_msr *save_msr(int index, struct saved_msr *entry)
{
        msr_t msr;

        msr = msr_read(index);
        entry->index = index;
        entry->lo = msr.lo;
        entry->hi = msr.hi;

        /* Return the next entry */
        entry++;
        return entry;
}

static int save_bsp_msrs(char *start, int size)
{
        int msr_count;
        int num_var_mtrrs;
        struct saved_msr *msr_entry;
        int i;
        msr_t msr;

        /* Determine number of MTRRs need to be saved */
        msr = msr_read(MTRR_CAP_MSR);
        num_var_mtrrs = msr.lo & 0xff;

        /* 2 * num_var_mtrrs for base and mask. +1 for IA32_MTRR_DEF_TYPE */
        msr_count = 2 * num_var_mtrrs + NUM_FIXED_MTRRS + 1;

        if ((msr_count * sizeof(struct saved_msr)) > size) {
                printf("Cannot mirror all %d msrs.\n", msr_count);
                return -ENOSPC;
        }

        msr_entry = (void *)start;
        for (i = 0; i < NUM_FIXED_MTRRS; i++)
                msr_entry = save_msr(fixed_mtrrs[i], msr_entry);

        for (i = 0; i < num_var_mtrrs; i++) {
                msr_entry = save_msr(MTRR_PHYS_BASE_MSR(i), msr_entry);
                msr_entry = save_msr(MTRR_PHYS_MASK_MSR(i), msr_entry);
        }

        msr_entry = save_msr(MTRR_DEF_TYPE_MSR, msr_entry);

        return msr_count;
}

static int load_sipi_vector(atomic_t **ap_countp)
{
        struct sipi_params_16bit *params16;
        struct sipi_params *params;
        static char msr_save[512];
        char *stack;
        ulong addr;
        int code_len;
        int size;
        int ret;

        /* Copy in the code */
        code_len = ap_start16_code_end - ap_start16;
        debug("Copying SIPI code to %x: %d bytes\n", AP_DEFAULT_BASE,
              code_len);
        memcpy((void *)AP_DEFAULT_BASE, ap_start16, code_len);

        addr = AP_DEFAULT_BASE + (ulong)sipi_params_16bit - (ulong)ap_start16;
        params16 = (struct sipi_params_16bit *)addr;
        params16->ap_start = (uint32_t)ap_start;
        params16->gdt = (uint32_t)gd->arch.gdt;
        params16->gdt_limit = X86_GDT_SIZE - 1;
        debug("gdt = %x, gdt_limit = %x\n", params16->gdt, params16->gdt_limit);

        params = (struct sipi_params *)sipi_params;
        debug("SIPI 32-bit params at %p\n", params);
        params->idt_ptr = (uint32_t)x86_get_idt();

        params->stack_size = CONFIG_AP_STACK_SIZE;
        size = params->stack_size * CONFIG_MAX_CPUS;
        stack = memalign(size, 4096);
        if (!stack)
                return -ENOMEM;
        params->stack_top = (u32)(stack + size);

        params->microcode_ptr = 0;
        params->msr_table_ptr = (u32)msr_save;
        ret = save_bsp_msrs(msr_save, sizeof(msr_save));
        if (ret < 0)
                return ret;
        params->msr_count = ret;

        params->c_handler = (uint32_t)&ap_init;

        *ap_countp = &params->ap_count;
        atomic_set(*ap_countp, 0);
        debug("SIPI vector is ready\n");

        return 0;
}

static int check_cpu_devices(int expected_cpus)
{
        int i;

        for (i = 0; i < expected_cpus; i++) {
                struct udevice *dev;
                int ret;

                ret = uclass_find_device(UCLASS_CPU, i, &dev);
                if (ret) {
                        debug("Cannot find CPU %d in device tree\n", i);
                        return ret;
                }
        }

        return 0;
}

/* Returns 1 for timeout. 0 on success */
static int apic_wait_timeout(int total_delay, int delay_step)
{
        int total = 0;
        int timeout = 0;

        while (lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY) {
                udelay(delay_step);
                total += delay_step;
                if (total >= total_delay) {
                        timeout = 1;
                        break;
                }
        }

        return timeout;
}

static int start_aps(int ap_count, atomic_t *num_aps)
{
        int sipi_vector;
        /* Max location is 4KiB below 1MiB */
        const int max_vector_loc = ((1 << 20) - (1 << 12)) >> 12;

        if (ap_count == 0)
                return 0;

        /* The vector is sent as a 4k aligned address in one byte */
        sipi_vector = AP_DEFAULT_BASE >> 12;

        if (sipi_vector > max_vector_loc) {
                printf("SIPI vector too large! 0x%08x\n",
                       sipi_vector);
                return -1;
        }

        debug("Attempting to start %d APs\n", ap_count);

        if ((lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY)) {
                debug("Waiting for ICR not to be busy...");
                if (apic_wait_timeout(1000, 50)) {
                        debug("timed out. Aborting.\n");
                        return -1;
                } else {
                        debug("done.\n");
                }
        }

        /* Send INIT IPI to all but self */
        lapic_write(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(0));
        lapic_write(LAPIC_ICR, LAPIC_DEST_ALLBUT | LAPIC_INT_ASSERT |
                    LAPIC_DM_INIT);
        debug("Waiting for 10ms after sending INIT.\n");
        mdelay(10);

        /* Send 1st SIPI */
        if ((lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY)) {
                debug("Waiting for ICR not to be busy...");
                if (apic_wait_timeout(1000, 50)) {
                        debug("timed out. Aborting.\n");
                        return -1;
                } else {
                        debug("done.\n");
                }
        }

        lapic_write(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(0));
        lapic_write(LAPIC_ICR, LAPIC_DEST_ALLBUT | LAPIC_INT_ASSERT |
                    LAPIC_DM_STARTUP | sipi_vector);
        debug("Waiting for 1st SIPI to complete...");
        if (apic_wait_timeout(10000, 50)) {
                debug("timed out.\n");
                return -1;
        } else {
                debug("done.\n");
        }

        /* Wait for CPUs to check in up to 200 us */
        wait_for_aps(num_aps, ap_count, 200, 15);

        /* Send 2nd SIPI */
        if ((lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY)) {
                debug("Waiting for ICR not to be busy...");
                if (apic_wait_timeout(1000, 50)) {
                        debug("timed out. Aborting.\n");
                        return -1;
                } else {
                        debug("done.\n");
                }
        }

        lapic_write(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(0));
        lapic_write(LAPIC_ICR, LAPIC_DEST_ALLBUT | LAPIC_INT_ASSERT |
                    LAPIC_DM_STARTUP | sipi_vector);
        debug("Waiting for 2nd SIPI to complete...");
        if (apic_wait_timeout(10000, 50)) {
                debug("timed out.\n");
                return -1;
        } else {
                debug("done.\n");
        }

        /* Wait for CPUs to check in */
        if (wait_for_aps(num_aps, ap_count, 10000, 50)) {
                debug("Not all APs checked in: %d/%d.\n",
                      atomic_read(num_aps), ap_count);
                return -1;
        }

        return 0;
}

static int bsp_do_flight_plan(struct udevice *cpu, struct mp_params *mp_params)
{
        int i;
        int ret = 0;
        const int timeout_us = 100000;
        const int step_us = 100;
        int num_aps = num_cpus - 1;

        for (i = 0; i < mp_params->num_records; i++) {
                struct mp_flight_record *rec = &mp_params->flight_plan[i];

                /* Wait for APs if the record is not released */
                if (atomic_read(&rec->barrier) == 0) {
                        /* Wait for the APs to check in */
                        if (wait_for_aps(&rec->cpus_entered, num_aps,
                                         timeout_us, step_us)) {
                                debug("MP record %d timeout.\n", i);
                                ret = -1;
                        }
                }

                if (rec->bsp_call != NULL)
                        rec->bsp_call(cpu, rec->bsp_arg);

                release_barrier(&rec->barrier);
        }
        return ret;
}

static int init_bsp(struct udevice **devp)
{
        char processor_name[CPU_MAX_NAME_LEN];
        int apic_id;
        int ret;

        cpu_get_name(processor_name);
        debug("CPU: %s.\n", processor_name);

        lapic_setup();

        apic_id = lapicid();
        ret = find_cpu_by_apid_id(apic_id, devp);
        if (ret) {
                printf("Cannot find boot CPU, APIC ID %d\n", apic_id);
                return ret;
        }

        return 0;
}

int mp_init(struct mp_params *p)
{
        int num_aps;
        atomic_t *ap_count;
        struct udevice *cpu;
        int ret;

        /* This will cause the CPUs devices to be bound */
        struct uclass *uc;
        ret = uclass_get(UCLASS_CPU, &uc);
        if (ret)
                return ret;

        ret = init_bsp(&cpu);
        if (ret) {
                debug("Cannot init boot CPU: err=%d\n", ret);
                return ret;
        }

        if (p == NULL || p->flight_plan == NULL || p->num_records < 1) {
                printf("Invalid MP parameters\n");
                return -1;
        }

        num_cpus = cpu_get_count(cpu);
        if (num_cpus < 0) {
                debug("Cannot get number of CPUs: err=%d\n", num_cpus);
                return num_cpus;
        }

        if (num_cpus < 2)
                debug("Warning: Only 1 CPU is detected\n");

        ret = check_cpu_devices(num_cpus);
        if (ret)
                debug("Warning: Device tree does not describe all CPUs. Extra ones will not be started correctly\n");

        /* Copy needed parameters so that APs have a reference to the plan */
        mp_info.num_records = p->num_records;
        mp_info.records = p->flight_plan;

        /* Load the SIPI vector */
        ret = load_sipi_vector(&ap_count);
        if (ap_count == NULL)
                return -1;

        /*
         * Make sure SIPI data hits RAM so the APs that come up will see
         * the startup code even if the caches are disabled
         */
        wbinvd();

        /* Start the APs providing number of APs and the cpus_entered field */
        num_aps = num_cpus - 1;
        ret = start_aps(num_aps, ap_count);
        if (ret) {
                mdelay(1000);
                debug("%d/%d eventually checked in?\n", atomic_read(ap_count),
                      num_aps);
                return ret;
        }

        /* Walk the flight plan for the BSP */
        ret = bsp_do_flight_plan(cpu, p);
        if (ret) {
                debug("CPU init failed: err=%d\n", ret);
                return ret;
        }

        return 0;
}

int mp_init_cpu(struct udevice *cpu, void *unused)
{
        /*
         * Multiple APs are brought up simultaneously and they may get the same
         * seq num in the uclass_resolve_seq() during device_probe(). To avoid
         * this, set req_seq to the reg number in the device tree in advance.
         */
        cpu->req_seq = fdtdec_get_int(gd->fdt_blob, cpu->of_offset, "reg", -1);

        return device_probe(cpu);
}