/*
 * Copyright (c) 2010-2011 Samsung Electronics Co., Ltd.
 *              http://www.samsung.com
 *
 * Cloned from linux/arch/arm/mach-vexpress/platsmp.c
 *
 *  Copyright (C) 2002 ARM Ltd.
 *  All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
*/

#include <linux/init.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/smp.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/soc/samsung/exynos-regs-pmu.h>

#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/smp_plat.h>
#include <asm/smp_scu.h>
#include <asm/firmware.h>

#include <mach/map.h>

#include "common.h"

extern void exynos4_secondary_startup(void);

#ifdef CONFIG_HOTPLUG_CPU
static inline void cpu_leave_lowpower(u32 core_id)
{
        unsigned int v;

        asm volatile(
        "mrc    p15, 0, %0, c1, c0, 0\n"
        "       orr     %0, %0, %1\n"
        "       mcr     p15, 0, %0, c1, c0, 0\n"
        "       mrc     p15, 0, %0, c1, c0, 1\n"
        "       orr     %0, %0, %2\n"
        "       mcr     p15, 0, %0, c1, c0, 1\n"
          : "=&r" (v)
          : "Ir" (CR_C), "Ir" (0x40)
          : "cc");
}

static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
{
        u32 mpidr = cpu_logical_map(cpu);
        u32 core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);

        for (;;) {

                /* Turn the CPU off on next WFI instruction. */
                exynos_cpu_power_down(core_id);

                wfi();

                if (pen_release == core_id) {
                        /*
                         * OK, proper wakeup, we're done
                         */
                        break;
                }

                /*
                 * Getting here, means that we have come out of WFI without
                 * having been woken up - this shouldn't happen
                 *
                 * Just note it happening - when we're woken, we can report
                 * its occurrence.
                 */
                (*spurious)++;
        }
}
#endif /* CONFIG_HOTPLUG_CPU */

/**
 * exynos_core_power_down : power down the specified cpu
 * @cpu : the cpu to power down
 *
 * Power down the specified cpu. The sequence must be finished by a
 * call to cpu_do_idle()
 *
 */
void exynos_cpu_power_down(int cpu)
{
        u32 core_conf;

        if (cpu == 0 && (soc_is_exynos5420() || soc_is_exynos5800())) {
                /*
                 * Bypass power down for CPU0 during suspend. Check for
                 * the SYS_PWR_REG value to decide if we are suspending
                 * the system.
                 */
                int val = pmu_raw_readl(EXYNOS5_ARM_CORE0_SYS_PWR_REG);

                if (!(val & S5P_CORE_LOCAL_PWR_EN))
                        return;
        }

        core_conf = pmu_raw_readl(EXYNOS_ARM_CORE_CONFIGURATION(cpu));
        core_conf &= ~S5P_CORE_LOCAL_PWR_EN;
        pmu_raw_writel(core_conf, EXYNOS_ARM_CORE_CONFIGURATION(cpu));
}

/**
 * exynos_cpu_power_up : power up the specified cpu
 * @cpu : the cpu to power up
 *
 * Power up the specified cpu
 */
void exynos_cpu_power_up(int cpu)
{
        u32 core_conf = S5P_CORE_LOCAL_PWR_EN;

        if (soc_is_exynos3250())
                core_conf |= S5P_CORE_AUTOWAKEUP_EN;

        pmu_raw_writel(core_conf,
                        EXYNOS_ARM_CORE_CONFIGURATION(cpu));
}

/**
 * exynos_cpu_power_state : returns the power state of the cpu
 * @cpu : the cpu to retrieve the power state from
 *
 */
int exynos_cpu_power_state(int cpu)
{
        return (pmu_raw_readl(EXYNOS_ARM_CORE_STATUS(cpu)) &
                        S5P_CORE_LOCAL_PWR_EN);
}

/**
 * exynos_cluster_power_down : power down the specified cluster
 * @cluster : the cluster to power down
 */
void exynos_cluster_power_down(int cluster)
{
        pmu_raw_writel(0, EXYNOS_COMMON_CONFIGURATION(cluster));
}

/**
 * exynos_cluster_power_up : power up the specified cluster
 * @cluster : the cluster to power up
 */
void exynos_cluster_power_up(int cluster)
{
        pmu_raw_writel(S5P_CORE_LOCAL_PWR_EN,
                        EXYNOS_COMMON_CONFIGURATION(cluster));
}

/**
 * exynos_cluster_power_state : returns the power state of the cluster
 * @cluster : the cluster to retrieve the power state from
 *
 */
int exynos_cluster_power_state(int cluster)
{
        return (pmu_raw_readl(EXYNOS_COMMON_STATUS(cluster)) &
                S5P_CORE_LOCAL_PWR_EN);
}

static void __iomem *cpu_boot_reg_base(void)
{
        if (soc_is_exynos4210() && samsung_rev() == EXYNOS4210_REV_1_1)
                return pmu_base_addr + S5P_INFORM5;
        return sysram_base_addr;
}

static inline void __iomem *cpu_boot_reg(int cpu)
{
        void __iomem *boot_reg;

        boot_reg = cpu_boot_reg_base();
        if (!boot_reg)
                return IOMEM_ERR_PTR(-ENODEV);
        if (soc_is_exynos4412())
                boot_reg += 4*cpu;
        else if (soc_is_exynos5420() || soc_is_exynos5800())
                boot_reg += 4;
        return boot_reg;
}

/*
 * Set wake up by local power mode and execute software reset for given core.
 *
 * Currently this is needed only when booting secondary CPU on Exynos3250.
 */
void exynos_core_restart(u32 core_id)
{
        u32 val;

        if (!of_machine_is_compatible("samsung,exynos3250"))
                return;

        while (!pmu_raw_readl(S5P_PMU_SPARE2))
                udelay(10);
        udelay(10);

        val = pmu_raw_readl(EXYNOS_ARM_CORE_STATUS(core_id));
        val |= S5P_CORE_WAKEUP_FROM_LOCAL_CFG;
        pmu_raw_writel(val, EXYNOS_ARM_CORE_STATUS(core_id));

        pmu_raw_writel(EXYNOS_CORE_PO_RESET(core_id), EXYNOS_SWRESET);
}

/*
 * Write pen_release in a way that is guaranteed to be visible to all
 * observers, irrespective of whether they're taking part in coherency
 * or not.  This is necessary for the hotplug code to work reliably.
 */
static void write_pen_release(int val)
{
        pen_release = val;
        smp_wmb();
        sync_cache_w(&pen_release);
}

static void __iomem *scu_base_addr(void)
{
        return (void __iomem *)(S5P_VA_SCU);
}

static DEFINE_SPINLOCK(boot_lock);

static void exynos_secondary_init(unsigned int cpu)
{
        /*
         * let the primary processor know we're out of the
         * pen, then head off into the C entry point
         */
        write_pen_release(-1);

        /*
         * Synchronise with the boot thread.
         */
        spin_lock(&boot_lock);
        spin_unlock(&boot_lock);
}

int exynos_set_boot_addr(u32 core_id, unsigned long boot_addr)
{
        int ret;

        /*
         * Try to set boot address using firmware first
         * and fall back to boot register if it fails.
         */
        ret = call_firmware_op(set_cpu_boot_addr, core_id, boot_addr);
        if (ret && ret != -ENOSYS)
                goto fail;
        if (ret == -ENOSYS) {
                void __iomem *boot_reg = cpu_boot_reg(core_id);

                if (IS_ERR(boot_reg)) {
                        ret = PTR_ERR(boot_reg);
                        goto fail;
                }
                __raw_writel(boot_addr, boot_reg);
                ret = 0;
        }
fail:
        return ret;
}

int exynos_get_boot_addr(u32 core_id, unsigned long *boot_addr)
{
        int ret;

        /*
         * Try to get boot address using firmware first
         * and fall back to boot register if it fails.
         */
        ret = call_firmware_op(get_cpu_boot_addr, core_id, boot_addr);
        if (ret && ret != -ENOSYS)
                goto fail;
        if (ret == -ENOSYS) {
                void __iomem *boot_reg = cpu_boot_reg(core_id);

                if (IS_ERR(boot_reg)) {
                        ret = PTR_ERR(boot_reg);
                        goto fail;
                }
                *boot_addr = __raw_readl(boot_reg);
                ret = 0;
        }
fail:
        return ret;
}

static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
{
        unsigned long timeout;
        u32 mpidr = cpu_logical_map(cpu);
        u32 core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
        int ret = -ENOSYS;

        /*
         * Set synchronisation state between this boot processor
         * and the secondary one
         */
        spin_lock(&boot_lock);

        /*
         * The secondary processor is waiting to be released from
         * the holding pen - release it, then wait for it to flag
         * that it has been released by resetting pen_release.
         *
         * Note that "pen_release" is the hardware CPU core ID, whereas
         * "cpu" is Linux's internal ID.
         */
        write_pen_release(core_id);

        if (!exynos_cpu_power_state(core_id)) {
                exynos_cpu_power_up(core_id);
                timeout = 10;

                /* wait max 10 ms until cpu1 is on */
                while (exynos_cpu_power_state(core_id)
                       != S5P_CORE_LOCAL_PWR_EN) {
                        if (timeout-- == 0)
                                break;

                        mdelay(1);
                }

                if (timeout == 0) {
                        printk(KERN_ERR "cpu1 power enable failed");
                        spin_unlock(&boot_lock);
                        return -ETIMEDOUT;
                }
        }

        exynos_core_restart(core_id);

        /*
         * Send the secondary CPU a soft interrupt, thereby causing
         * the boot monitor to read the system wide flags register,
         * and branch to the address found there.
         */

        timeout = jiffies + (1 * HZ);
        while (time_before(jiffies, timeout)) {
                unsigned long boot_addr;

                smp_rmb();

                boot_addr = virt_to_phys(exynos4_secondary_startup);

                ret = exynos_set_boot_addr(core_id, boot_addr);
                if (ret)
                        goto fail;

                call_firmware_op(cpu_boot, core_id);

                if (soc_is_exynos3250())
                        dsb_sev();
                else
                        arch_send_wakeup_ipi_mask(cpumask_of(cpu));

                if (pen_release == -1)
                        break;

                udelay(10);
        }

        if (pen_release != -1)
                ret = -ETIMEDOUT;

        /*
         * now the secondary core is starting up let it run its
         * calibrations, then wait for it to finish
         */
fail:
        spin_unlock(&boot_lock);

        return pen_release != -1 ? ret : 0;
}

/*
 * Initialise the CPU possible map early - this describes the CPUs
 * which may be present or become present in the system.
 */

static void __init exynos_smp_init_cpus(void)
{
        void __iomem *scu_base = scu_base_addr();
        unsigned int i, ncores;

        if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A9)
                ncores = scu_base ? scu_get_core_count(scu_base) : 1;
        else
                /*
                 * CPU Nodes are passed thru DT and set_cpu_possible
                 * is set by "arm_dt_init_cpu_maps".
                 */
                return;

        /* sanity check */
        if (ncores > nr_cpu_ids) {
                pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
                        ncores, nr_cpu_ids);
                ncores = nr_cpu_ids;
        }

        for (i = 0; i < ncores; i++)
                set_cpu_possible(i, true);
}

static void __init exynos_smp_prepare_cpus(unsigned int max_cpus)
{
        int i;

        exynos_sysram_init();

        exynos_set_delayed_reset_assertion(true);

        if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A9)
                scu_enable(scu_base_addr());

        /*
         * Write the address of secondary startup into the
         * system-wide flags register. The boot monitor waits
         * until it receives a soft interrupt, and then the
         * secondary CPU branches to this address.
         *
         * Try using firmware operation first and fall back to
         * boot register if it fails.
         */
        for (i = 1; i < max_cpus; ++i) {
                unsigned long boot_addr;
                u32 mpidr;
                u32 core_id;
                int ret;

                mpidr = cpu_logical_map(i);
                core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
                boot_addr = virt_to_phys(exynos4_secondary_startup);

                ret = exynos_set_boot_addr(core_id, boot_addr);
                if (ret)
                        break;
        }
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * platform-specific code to shutdown a CPU
 *
 * Called with IRQs disabled
 */
static void exynos_cpu_die(unsigned int cpu)
{
        int spurious = 0;
        u32 mpidr = cpu_logical_map(cpu);
        u32 core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);

        v7_exit_coherency_flush(louis);

        platform_do_lowpower(cpu, &spurious);

        /*
         * bring this CPU back into the world of cache
         * coherency, and then restore interrupts
         */
        cpu_leave_lowpower(core_id);

        if (spurious)
                pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
}
#endif /* CONFIG_HOTPLUG_CPU */

const struct smp_operations exynos_smp_ops __initconst = {
        .smp_init_cpus          = exynos_smp_init_cpus,
        .smp_prepare_cpus       = exynos_smp_prepare_cpus,
        .smp_secondary_init     = exynos_secondary_init,
        .smp_boot_secondary     = exynos_boot_secondary,
#ifdef CONFIG_HOTPLUG_CPU
        .cpu_die                = exynos_cpu_die,
#endif
};