// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2018 Chen-Yu Tsai
 *
 * Chen-Yu Tsai <wens@csie.org>
 *
 * arch/arm/mach-sunxi/mc_smp.c
 *
 * Based on Allwinner code, arch/arm/mach-exynos/mcpm-exynos.c, and
 * arch/arm/mach-hisi/platmcpm.c
 * Cluster cache enable trampoline code adapted from MCPM framework
 */

#include <linux/arm-cci.h>
#include <linux/cpu_pm.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/irqchip/arm-gic.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/smp.h>

#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/cputype.h>
#include <asm/idmap.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>

#define SUNXI_CPUS_PER_CLUSTER          4
#define SUNXI_NR_CLUSTERS               2

#define POLL_USEC       100
#define TIMEOUT_USEC    100000

#define CPUCFG_CX_CTRL_REG0(c)          (0x10 * (c))
#define CPUCFG_CX_CTRL_REG0_L1_RST_DISABLE(n)   BIT(n)
#define CPUCFG_CX_CTRL_REG0_L1_RST_DISABLE_ALL  0xf
#define CPUCFG_CX_CTRL_REG0_L2_RST_DISABLE_A7   BIT(4)
#define CPUCFG_CX_CTRL_REG0_L2_RST_DISABLE_A15  BIT(0)
#define CPUCFG_CX_CTRL_REG1(c)          (0x10 * (c) + 0x4)
#define CPUCFG_CX_CTRL_REG1_ACINACTM    BIT(0)
#define CPUCFG_CX_STATUS(c)             (0x30 + 0x4 * (c))
#define CPUCFG_CX_STATUS_STANDBYWFI(n)  BIT(16 + (n))
#define CPUCFG_CX_STATUS_STANDBYWFIL2   BIT(0)
#define CPUCFG_CX_RST_CTRL(c)           (0x80 + 0x4 * (c))
#define CPUCFG_CX_RST_CTRL_DBG_SOC_RST  BIT(24)
#define CPUCFG_CX_RST_CTRL_ETM_RST(n)   BIT(20 + (n))
#define CPUCFG_CX_RST_CTRL_ETM_RST_ALL  (0xf << 20)
#define CPUCFG_CX_RST_CTRL_DBG_RST(n)   BIT(16 + (n))
#define CPUCFG_CX_RST_CTRL_DBG_RST_ALL  (0xf << 16)
#define CPUCFG_CX_RST_CTRL_H_RST        BIT(12)
#define CPUCFG_CX_RST_CTRL_L2_RST       BIT(8)
#define CPUCFG_CX_RST_CTRL_CX_RST(n)    BIT(4 + (n))
#define CPUCFG_CX_RST_CTRL_CORE_RST(n)  BIT(n)
#define CPUCFG_CX_RST_CTRL_CORE_RST_ALL (0xf << 0)

#define PRCM_CPU_PO_RST_CTRL(c)         (0x4 + 0x4 * (c))
#define PRCM_CPU_PO_RST_CTRL_CORE(n)    BIT(n)
#define PRCM_CPU_PO_RST_CTRL_CORE_ALL   0xf
#define PRCM_PWROFF_GATING_REG(c)       (0x100 + 0x4 * (c))
/* The power off register for clusters are different from a80 and a83t */
#define PRCM_PWROFF_GATING_REG_CLUSTER_SUN8I    BIT(0)
#define PRCM_PWROFF_GATING_REG_CLUSTER_SUN9I    BIT(4)
#define PRCM_PWROFF_GATING_REG_CORE(n)  BIT(n)
#define PRCM_PWR_SWITCH_REG(c, cpu)     (0x140 + 0x10 * (c) + 0x4 * (cpu))
#define PRCM_CPU_SOFT_ENTRY_REG         0x164

/* R_CPUCFG registers, specific to sun8i-a83t */
#define R_CPUCFG_CLUSTER_PO_RST_CTRL(c) (0x30 + (c) * 0x4)
#define R_CPUCFG_CLUSTER_PO_RST_CTRL_CORE(n)    BIT(n)
#define R_CPUCFG_CPU_SOFT_ENTRY_REG             0x01a4

#define CPU0_SUPPORT_HOTPLUG_MAGIC0     0xFA50392F
#define CPU0_SUPPORT_HOTPLUG_MAGIC1     0x790DCA3A

static void __iomem *cpucfg_base;
static void __iomem *prcm_base;
static void __iomem *sram_b_smp_base;
static void __iomem *r_cpucfg_base;

extern void sunxi_mc_smp_secondary_startup(void);
extern void sunxi_mc_smp_resume(void);
static bool is_a83t;

static bool sunxi_core_is_cortex_a15(unsigned int core, unsigned int cluster)
{
        struct device_node *node;
        int cpu = cluster * SUNXI_CPUS_PER_CLUSTER + core;
        bool is_compatible;

        node = of_cpu_device_node_get(cpu);

        /* In case of_cpu_device_node_get fails */
        if (!node)
                node = of_get_cpu_node(cpu, NULL);

        if (!node) {
                /*
                 * There's no point in returning an error, since we
                 * would be mid way in a core or cluster power sequence.
                 */
                pr_err("%s: Couldn't get CPU cluster %u core %u device node\n",
                       __func__, cluster, core);

                return false;
        }

        is_compatible = of_device_is_compatible(node, "arm,cortex-a15");
        of_node_put(node);
        return is_compatible;
}

static int sunxi_cpu_power_switch_set(unsigned int cpu, unsigned int cluster,
                                      bool enable)
{
        u32 reg;

        /* control sequence from Allwinner A80 user manual v1.2 PRCM section */
        reg = readl(prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
        if (enable) {
                if (reg == 0x00) {
                        pr_debug("power clamp for cluster %u cpu %u already open\n",
                                 cluster, cpu);
                        return 0;
                }

                writel(0xff, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
                udelay(10);
                writel(0xfe, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
                udelay(10);
                writel(0xf8, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
                udelay(10);
                writel(0xf0, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
                udelay(10);
                writel(0x00, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
                udelay(10);
        } else {
                writel(0xff, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
                udelay(10);
        }

        return 0;
}

static void sunxi_cpu0_hotplug_support_set(bool enable)
{
        if (enable) {
                writel(CPU0_SUPPORT_HOTPLUG_MAGIC0, sram_b_smp_base);
                writel(CPU0_SUPPORT_HOTPLUG_MAGIC1, sram_b_smp_base + 0x4);
        } else {
                writel(0x0, sram_b_smp_base);
                writel(0x0, sram_b_smp_base + 0x4);
        }
}

static int sunxi_cpu_powerup(unsigned int cpu, unsigned int cluster)
{
        u32 reg;

        pr_debug("%s: cluster %u cpu %u\n", __func__, cluster, cpu);
        if (cpu >= SUNXI_CPUS_PER_CLUSTER || cluster >= SUNXI_NR_CLUSTERS)
                return -EINVAL;

        /* Set hotplug support magic flags for cpu0 */
        if (cluster == 0 && cpu == 0)
                sunxi_cpu0_hotplug_support_set(true);

        /* assert processor power-on reset */
        reg = readl(prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
        reg &= ~PRCM_CPU_PO_RST_CTRL_CORE(cpu);
        writel(reg, prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));

        if (is_a83t) {
                /* assert cpu power-on reset */
                reg  = readl(r_cpucfg_base +
                             R_CPUCFG_CLUSTER_PO_RST_CTRL(cluster));
                reg &= ~(R_CPUCFG_CLUSTER_PO_RST_CTRL_CORE(cpu));
                writel(reg, r_cpucfg_base +
                       R_CPUCFG_CLUSTER_PO_RST_CTRL(cluster));
                udelay(10);
        }

        /* Cortex-A7: hold L1 reset disable signal low */
        if (!sunxi_core_is_cortex_a15(cpu, cluster)) {
                reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG0(cluster));
                reg &= ~CPUCFG_CX_CTRL_REG0_L1_RST_DISABLE(cpu);
                writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG0(cluster));
        }

        /* assert processor related resets */
        reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
        reg &= ~CPUCFG_CX_RST_CTRL_DBG_RST(cpu);

        /*
         * Allwinner code also asserts resets for NEON on A15. According
         * to ARM manuals, asserting power-on reset is sufficient.
         */
        if (!sunxi_core_is_cortex_a15(cpu, cluster))
                reg &= ~CPUCFG_CX_RST_CTRL_ETM_RST(cpu);

        writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));

        /* open power switch */
        sunxi_cpu_power_switch_set(cpu, cluster, true);

        /* Handle A83T bit swap */
        if (is_a83t) {
                if (cpu == 0)
                        cpu = 4;
        }

        /* clear processor power gate */
        reg = readl(prcm_base + PRCM_PWROFF_GATING_REG(cluster));
        reg &= ~PRCM_PWROFF_GATING_REG_CORE(cpu);
        writel(reg, prcm_base + PRCM_PWROFF_GATING_REG(cluster));
        udelay(20);

        /* Handle A83T bit swap */
        if (is_a83t) {
                if (cpu == 4)
                        cpu = 0;
        }

        /* de-assert processor power-on reset */
        reg = readl(prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
        reg |= PRCM_CPU_PO_RST_CTRL_CORE(cpu);
        writel(reg, prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));

        if (is_a83t) {
                reg  = readl(r_cpucfg_base +
                             R_CPUCFG_CLUSTER_PO_RST_CTRL(cluster));
                reg |= R_CPUCFG_CLUSTER_PO_RST_CTRL_CORE(cpu);
                writel(reg, r_cpucfg_base +
                       R_CPUCFG_CLUSTER_PO_RST_CTRL(cluster));
                udelay(10);
        }

        /* de-assert all processor resets */
        reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
        reg |= CPUCFG_CX_RST_CTRL_DBG_RST(cpu);
        reg |= CPUCFG_CX_RST_CTRL_CORE_RST(cpu);
        if (!sunxi_core_is_cortex_a15(cpu, cluster))
                reg |= CPUCFG_CX_RST_CTRL_ETM_RST(cpu);
        else
                reg |= CPUCFG_CX_RST_CTRL_CX_RST(cpu); /* NEON */
        writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));

        return 0;
}

static int sunxi_cluster_powerup(unsigned int cluster)
{
        u32 reg;

        pr_debug("%s: cluster %u\n", __func__, cluster);
        if (cluster >= SUNXI_NR_CLUSTERS)
                return -EINVAL;

        /* For A83T, assert cluster cores resets */
        if (is_a83t) {
                reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
                reg &= ~CPUCFG_CX_RST_CTRL_CORE_RST_ALL;   /* Core Reset    */
                writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
                udelay(10);
        }

        /* assert ACINACTM */
        reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
        reg |= CPUCFG_CX_CTRL_REG1_ACINACTM;
        writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));

        /* assert cluster processor power-on resets */
        reg = readl(prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
        reg &= ~PRCM_CPU_PO_RST_CTRL_CORE_ALL;
        writel(reg, prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));

        /* assert cluster cores resets */
        if (is_a83t) {
                reg  = readl(r_cpucfg_base +
                             R_CPUCFG_CLUSTER_PO_RST_CTRL(cluster));
                reg &= ~CPUCFG_CX_RST_CTRL_CORE_RST_ALL;
                writel(reg, r_cpucfg_base +
                       R_CPUCFG_CLUSTER_PO_RST_CTRL(cluster));
                udelay(10);
        }

        /* assert cluster resets */
        reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
        reg &= ~CPUCFG_CX_RST_CTRL_DBG_SOC_RST;
        reg &= ~CPUCFG_CX_RST_CTRL_DBG_RST_ALL;
        reg &= ~CPUCFG_CX_RST_CTRL_H_RST;
        reg &= ~CPUCFG_CX_RST_CTRL_L2_RST;

        /*
         * Allwinner code also asserts resets for NEON on A15. According
         * to ARM manuals, asserting power-on reset is sufficient.
         */
        if (!sunxi_core_is_cortex_a15(0, cluster))
                reg &= ~CPUCFG_CX_RST_CTRL_ETM_RST_ALL;

        writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));

        /* hold L1/L2 reset disable signals low */
        reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG0(cluster));
        if (sunxi_core_is_cortex_a15(0, cluster)) {
                /* Cortex-A15: hold L2RSTDISABLE low */
                reg &= ~CPUCFG_CX_CTRL_REG0_L2_RST_DISABLE_A15;
        } else {
                /* Cortex-A7: hold L1RSTDISABLE and L2RSTDISABLE low */
                reg &= ~CPUCFG_CX_CTRL_REG0_L1_RST_DISABLE_ALL;
                reg &= ~CPUCFG_CX_CTRL_REG0_L2_RST_DISABLE_A7;
        }
        writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG0(cluster));

        /* clear cluster power gate */
        reg = readl(prcm_base + PRCM_PWROFF_GATING_REG(cluster));
        if (is_a83t)
                reg &= ~PRCM_PWROFF_GATING_REG_CLUSTER_SUN8I;
        else
                reg &= ~PRCM_PWROFF_GATING_REG_CLUSTER_SUN9I;
        writel(reg, prcm_base + PRCM_PWROFF_GATING_REG(cluster));
        udelay(20);

        /* de-assert cluster resets */
        reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
        reg |= CPUCFG_CX_RST_CTRL_DBG_SOC_RST;
        reg |= CPUCFG_CX_RST_CTRL_H_RST;
        reg |= CPUCFG_CX_RST_CTRL_L2_RST;
        writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));

        /* de-assert ACINACTM */
        reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
        reg &= ~CPUCFG_CX_CTRL_REG1_ACINACTM;
        writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));

        return 0;
}

/*
 * This bit is shared between the initial nocache_trampoline call to
 * enable CCI-400 and proper cluster cache disable before power down.
 */
static void sunxi_cluster_cache_disable_without_axi(void)
{
        if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A15) {
                /*
                 * On the Cortex-A15 we need to disable
                 * L2 prefetching before flushing the cache.
                 */
                asm volatile(
                "mcr    p15, 1, %0, c15, c0, 3\n"
                "isb\n"
                "dsb"
                : : "r" (0x400));
        }

        /* Flush all cache levels for this cluster. */
        v7_exit_coherency_flush(all);

        /*
         * Disable cluster-level coherency by masking
         * incoming snoops and DVM messages:
         */
        cci_disable_port_by_cpu(read_cpuid_mpidr());
}

static int sunxi_mc_smp_cpu_table[SUNXI_NR_CLUSTERS][SUNXI_CPUS_PER_CLUSTER];
int sunxi_mc_smp_first_comer;

static DEFINE_SPINLOCK(boot_lock);

static bool sunxi_mc_smp_cluster_is_down(unsigned int cluster)
{
        int i;

        for (i = 0; i < SUNXI_CPUS_PER_CLUSTER; i++)
                if (sunxi_mc_smp_cpu_table[cluster][i])
                        return false;
        return true;
}

static void sunxi_mc_smp_secondary_init(unsigned int cpu)
{
        /* Clear hotplug support magic flags for cpu0 */
        if (cpu == 0)
                sunxi_cpu0_hotplug_support_set(false);
}

static int sunxi_mc_smp_boot_secondary(unsigned int l_cpu, struct task_struct *idle)
{
        unsigned int mpidr, cpu, cluster;

        mpidr = cpu_logical_map(l_cpu);
        cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
        cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);

        if (!cpucfg_base)
                return -ENODEV;
        if (cluster >= SUNXI_NR_CLUSTERS || cpu >= SUNXI_CPUS_PER_CLUSTER)
                return -EINVAL;

        spin_lock_irq(&boot_lock);

        if (sunxi_mc_smp_cpu_table[cluster][cpu])
                goto out;

        if (sunxi_mc_smp_cluster_is_down(cluster)) {
                sunxi_mc_smp_first_comer = true;
                sunxi_cluster_powerup(cluster);
        } else {
                sunxi_mc_smp_first_comer = false;
        }

        /* This is read by incoming CPUs with their cache and MMU disabled */
        sync_cache_w(&sunxi_mc_smp_first_comer);
        sunxi_cpu_powerup(cpu, cluster);

out:
        sunxi_mc_smp_cpu_table[cluster][cpu]++;
        spin_unlock_irq(&boot_lock);

        return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
static void sunxi_cluster_cache_disable(void)
{
        unsigned int cluster = MPIDR_AFFINITY_LEVEL(read_cpuid_mpidr(), 1);
        u32 reg;

        pr_debug("%s: cluster %u\n", __func__, cluster);

        sunxi_cluster_cache_disable_without_axi();

        /* last man standing, assert ACINACTM */
        reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
        reg |= CPUCFG_CX_CTRL_REG1_ACINACTM;
        writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
}

static void sunxi_mc_smp_cpu_die(unsigned int l_cpu)
{
        unsigned int mpidr, cpu, cluster;
        bool last_man;

        mpidr = cpu_logical_map(l_cpu);
        cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
        cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
        pr_debug("%s: cluster %u cpu %u\n", __func__, cluster, cpu);

        spin_lock(&boot_lock);
        sunxi_mc_smp_cpu_table[cluster][cpu]--;
        if (sunxi_mc_smp_cpu_table[cluster][cpu] == 1) {
                /* A power_up request went ahead of us. */
                pr_debug("%s: aborting due to a power up request\n",
                         __func__);
                spin_unlock(&boot_lock);
                return;
        } else if (sunxi_mc_smp_cpu_table[cluster][cpu] > 1) {
                pr_err("Cluster %d CPU%d boots multiple times\n",
                       cluster, cpu);
                BUG();
        }

        last_man = sunxi_mc_smp_cluster_is_down(cluster);
        spin_unlock(&boot_lock);

        gic_cpu_if_down(0);
        if (last_man)
                sunxi_cluster_cache_disable();
        else
                v7_exit_coherency_flush(louis);

        for (;;)
                wfi();
}

static int sunxi_cpu_powerdown(unsigned int cpu, unsigned int cluster)
{
        u32 reg;

        pr_debug("%s: cluster %u cpu %u\n", __func__, cluster, cpu);
        if (cpu >= SUNXI_CPUS_PER_CLUSTER || cluster >= SUNXI_NR_CLUSTERS)
                return -EINVAL;

        /* gate processor power */
        reg = readl(prcm_base + PRCM_PWROFF_GATING_REG(cluster));
        reg |= PRCM_PWROFF_GATING_REG_CORE(cpu);
        writel(reg, prcm_base + PRCM_PWROFF_GATING_REG(cluster));
        udelay(20);

        /* close power switch */
        sunxi_cpu_power_switch_set(cpu, cluster, false);

        return 0;
}

static int sunxi_cluster_powerdown(unsigned int cluster)
{
        u32 reg;

        pr_debug("%s: cluster %u\n", __func__, cluster);
        if (cluster >= SUNXI_NR_CLUSTERS)
                return -EINVAL;

        /* assert cluster resets or system will hang */
        pr_debug("%s: assert cluster reset\n", __func__);
        reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
        reg &= ~CPUCFG_CX_RST_CTRL_DBG_SOC_RST;
        reg &= ~CPUCFG_CX_RST_CTRL_H_RST;
        reg &= ~CPUCFG_CX_RST_CTRL_L2_RST;
        writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));

        /* gate cluster power */
        pr_debug("%s: gate cluster power\n", __func__);
        reg = readl(prcm_base + PRCM_PWROFF_GATING_REG(cluster));
        if (is_a83t)
                reg |= PRCM_PWROFF_GATING_REG_CLUSTER_SUN8I;
        else
                reg |= PRCM_PWROFF_GATING_REG_CLUSTER_SUN9I;
        writel(reg, prcm_base + PRCM_PWROFF_GATING_REG(cluster));
        udelay(20);

        return 0;
}

static int sunxi_mc_smp_cpu_kill(unsigned int l_cpu)
{
        unsigned int mpidr, cpu, cluster;
        unsigned int tries, count;
        int ret = 0;
        u32 reg;

        mpidr = cpu_logical_map(l_cpu);
        cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
        cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);

        /* This should never happen */
        if (WARN_ON(cluster >= SUNXI_NR_CLUSTERS ||
                    cpu >= SUNXI_CPUS_PER_CLUSTER))
                return 0;

        /* wait for CPU core to die and enter WFI */
        count = TIMEOUT_USEC / POLL_USEC;
        spin_lock_irq(&boot_lock);
        for (tries = 0; tries < count; tries++) {
                spin_unlock_irq(&boot_lock);
                usleep_range(POLL_USEC / 2, POLL_USEC);
                spin_lock_irq(&boot_lock);

                /*
                 * If the user turns off a bunch of cores at the same
                 * time, the kernel might call cpu_kill before some of
                 * them are ready. This is because boot_lock serializes
                 * both cpu_die and cpu_kill callbacks. Either one could
                 * run first. We should wait for cpu_die to complete.
                 */
                if (sunxi_mc_smp_cpu_table[cluster][cpu])
                        continue;

                reg = readl(cpucfg_base + CPUCFG_CX_STATUS(cluster));
                if (reg & CPUCFG_CX_STATUS_STANDBYWFI(cpu))
                        break;
        }

        if (tries >= count) {
                ret = ETIMEDOUT;
                goto out;
        }

        /* power down CPU core */
        sunxi_cpu_powerdown(cpu, cluster);

        if (!sunxi_mc_smp_cluster_is_down(cluster))
                goto out;

        /* wait for cluster L2 WFI */
        ret = readl_poll_timeout(cpucfg_base + CPUCFG_CX_STATUS(cluster), reg,
                                 reg & CPUCFG_CX_STATUS_STANDBYWFIL2,
                                 POLL_USEC, TIMEOUT_USEC);
        if (ret) {
                /*
                 * Ignore timeout on the cluster. Leaving the cluster on
                 * will not affect system execution, just use a bit more
                 * power. But returning an error here will only confuse
                 * the user as the CPU has already been shutdown.
                 */
                ret = 0;
                goto out;
        }

        /* Power down cluster */
        sunxi_cluster_powerdown(cluster);

out:
        spin_unlock_irq(&boot_lock);
        pr_debug("%s: cluster %u cpu %u powerdown: %d\n",
                 __func__, cluster, cpu, ret);
        return !ret;
}

static bool sunxi_mc_smp_cpu_can_disable(unsigned int cpu)
{
        /* CPU0 hotplug not handled for sun8i-a83t */
        if (is_a83t)
                if (cpu == 0)
                        return false;
        return true;
}
#endif

static const struct smp_operations sunxi_mc_smp_smp_ops __initconst = {
        .smp_secondary_init     = sunxi_mc_smp_secondary_init,
        .smp_boot_secondary     = sunxi_mc_smp_boot_secondary,
#ifdef CONFIG_HOTPLUG_CPU
        .cpu_die                = sunxi_mc_smp_cpu_die,
        .cpu_kill               = sunxi_mc_smp_cpu_kill,
        .cpu_can_disable        = sunxi_mc_smp_cpu_can_disable,
#endif
};

static bool __init sunxi_mc_smp_cpu_table_init(void)
{
        unsigned int mpidr, cpu, cluster;

        mpidr = read_cpuid_mpidr();
        cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
        cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);

        if (cluster >= SUNXI_NR_CLUSTERS || cpu >= SUNXI_CPUS_PER_CLUSTER) {
                pr_err("%s: boot CPU is out of bounds!\n", __func__);
                return false;
        }
        sunxi_mc_smp_cpu_table[cluster][cpu] = 1;
        return true;
}

/*
 * Adapted from arch/arm/common/mc_smp_entry.c
 *
 * We need the trampoline code to enable CCI-400 on the first cluster
 */
typedef typeof(cpu_reset) phys_reset_t;

static int __init nocache_trampoline(unsigned long __unused)
{
        phys_reset_t phys_reset;

        setup_mm_for_reboot();
        sunxi_cluster_cache_disable_without_axi();

        phys_reset = (phys_reset_t)(unsigned long)__pa_symbol(cpu_reset);
        phys_reset(__pa_symbol(sunxi_mc_smp_resume), false);
        BUG();
}

static int __init sunxi_mc_smp_loopback(void)
{
        int ret;

        /*
         * We're going to soft-restart the current CPU through the
         * low-level MCPM code by leveraging the suspend/resume
         * infrastructure. Let's play it safe by using cpu_pm_enter()
         * in case the CPU init code path resets the VFP or similar.
         */
        sunxi_mc_smp_first_comer = true;
        local_irq_disable();
        local_fiq_disable();
        ret = cpu_pm_enter();
        if (!ret) {
                ret = cpu_suspend(0, nocache_trampoline);
                cpu_pm_exit();
        }
        local_fiq_enable();
        local_irq_enable();
        sunxi_mc_smp_first_comer = false;

        return ret;
}

/*
 * This holds any device nodes that we requested resources for,
 * so that we may easily release resources in the error path.
 */
struct sunxi_mc_smp_nodes {
        struct device_node *prcm_node;
        struct device_node *cpucfg_node;
        struct device_node *sram_node;
        struct device_node *r_cpucfg_node;
};

/* This structure holds SoC-specific bits tied to an enable-method string. */
struct sunxi_mc_smp_data {
        const char *enable_method;
        int (*get_smp_nodes)(struct sunxi_mc_smp_nodes *nodes);
        bool is_a83t;
};

static void __init sunxi_mc_smp_put_nodes(struct sunxi_mc_smp_nodes *nodes)
{
        of_node_put(nodes->prcm_node);
        of_node_put(nodes->cpucfg_node);
        of_node_put(nodes->sram_node);
        of_node_put(nodes->r_cpucfg_node);
        memset(nodes, 0, sizeof(*nodes));
}

static int __init sun9i_a80_get_smp_nodes(struct sunxi_mc_smp_nodes *nodes)
{
        nodes->prcm_node = of_find_compatible_node(NULL, NULL,
                                                   "allwinner,sun9i-a80-prcm");
        if (!nodes->prcm_node) {
                pr_err("%s: PRCM not available\n", __func__);
                return -ENODEV;
        }

        nodes->cpucfg_node = of_find_compatible_node(NULL, NULL,
                                                     "allwinner,sun9i-a80-cpucfg");
        if (!nodes->cpucfg_node) {
                pr_err("%s: CPUCFG not available\n", __func__);
                return -ENODEV;
        }

        nodes->sram_node = of_find_compatible_node(NULL, NULL,
                                                   "allwinner,sun9i-a80-smp-sram");
        if (!nodes->sram_node) {
                pr_err("%s: Secure SRAM not available\n", __func__);
                return -ENODEV;
        }

        return 0;
}

static int __init sun8i_a83t_get_smp_nodes(struct sunxi_mc_smp_nodes *nodes)
{
        nodes->prcm_node = of_find_compatible_node(NULL, NULL,
                                                   "allwinner,sun8i-a83t-r-ccu");
        if (!nodes->prcm_node) {
                pr_err("%s: PRCM not available\n", __func__);
                return -ENODEV;
        }

        nodes->cpucfg_node = of_find_compatible_node(NULL, NULL,
                                                     "allwinner,sun8i-a83t-cpucfg");
        if (!nodes->cpucfg_node) {
                pr_err("%s: CPUCFG not available\n", __func__);
                return -ENODEV;
        }

        nodes->r_cpucfg_node = of_find_compatible_node(NULL, NULL,
                                                       "allwinner,sun8i-a83t-r-cpucfg");
        if (!nodes->r_cpucfg_node) {
                pr_err("%s: RCPUCFG not available\n", __func__);
                return -ENODEV;
        }

        return 0;
}

static const struct sunxi_mc_smp_data sunxi_mc_smp_data[] __initconst = {
        {
                .enable_method  = "allwinner,sun9i-a80-smp",
                .get_smp_nodes  = sun9i_a80_get_smp_nodes,
        },
        {
                .enable_method  = "allwinner,sun8i-a83t-smp",
                .get_smp_nodes  = sun8i_a83t_get_smp_nodes,
                .is_a83t        = true,
        },
};

static int __init sunxi_mc_smp_init(void)
{
        struct sunxi_mc_smp_nodes nodes = { 0 };
        struct device_node *node;
        struct resource res;
        void __iomem *addr;
        int i, ret;

        /*
         * Don't bother checking the "cpus" node, as an enable-method
         * property in that node is undocumented.
         */
        node = of_cpu_device_node_get(0);
        if (!node)
                return -ENODEV;

        /*
         * We can't actually use the enable-method magic in the kernel.
         * Our loopback / trampoline code uses the CPU suspend framework,
         * which requires the identity mapping be available. It would not
         * yet be available if we used the .init_cpus or .prepare_cpus
         * callbacks in smp_operations, which we would use if we were to
         * use CPU_METHOD_OF_DECLARE
         */
        for (i = 0; i < ARRAY_SIZE(sunxi_mc_smp_data); i++) {
                ret = of_property_match_string(node, "enable-method",
                                               sunxi_mc_smp_data[i].enable_method);
                if (!ret)
                        break;
        }

        is_a83t = sunxi_mc_smp_data[i].is_a83t;

        of_node_put(node);
        if (ret)
                return -ENODEV;

        if (!sunxi_mc_smp_cpu_table_init())
                return -EINVAL;

        if (!cci_probed()) {
                pr_err("%s: CCI-400 not available\n", __func__);
                return -ENODEV;
        }

        /* Get needed device tree nodes */
        ret = sunxi_mc_smp_data[i].get_smp_nodes(&nodes);
        if (ret)
                goto err_put_nodes;

        /*
         * Unfortunately we can not request the I/O region for the PRCM.
         * It is shared with the PRCM clock.
         */
        prcm_base = of_iomap(nodes.prcm_node, 0);
        if (!prcm_base) {
                pr_err("%s: failed to map PRCM registers\n", __func__);
                ret = -ENOMEM;
                goto err_put_nodes;
        }

        cpucfg_base = of_io_request_and_map(nodes.cpucfg_node, 0,
                                            "sunxi-mc-smp");
        if (IS_ERR(cpucfg_base)) {
                ret = PTR_ERR(cpucfg_base);
                pr_err("%s: failed to map CPUCFG registers: %d\n",
                       __func__, ret);
                goto err_unmap_prcm;
        }

        if (is_a83t) {
                r_cpucfg_base = of_io_request_and_map(nodes.r_cpucfg_node,
                                                      0, "sunxi-mc-smp");
                if (IS_ERR(r_cpucfg_base)) {
                        ret = PTR_ERR(r_cpucfg_base);
                        pr_err("%s: failed to map R-CPUCFG registers\n",
                               __func__);
                        goto err_unmap_release_cpucfg;
                }
        } else {
                sram_b_smp_base = of_io_request_and_map(nodes.sram_node, 0,
                                                        "sunxi-mc-smp");
                if (IS_ERR(sram_b_smp_base)) {
                        ret = PTR_ERR(sram_b_smp_base);
                        pr_err("%s: failed to map secure SRAM\n", __func__);
                        goto err_unmap_release_cpucfg;
                }
        }

        /* Configure CCI-400 for boot cluster */
        ret = sunxi_mc_smp_loopback();
        if (ret) {
                pr_err("%s: failed to configure boot cluster: %d\n",
                       __func__, ret);
                goto err_unmap_release_sram_rcpucfg;
        }

        /* We don't need the device nodes anymore */
        sunxi_mc_smp_put_nodes(&nodes);

        /* Set the hardware entry point address */
        if (is_a83t)
                addr = r_cpucfg_base + R_CPUCFG_CPU_SOFT_ENTRY_REG;
        else
                addr = prcm_base + PRCM_CPU_SOFT_ENTRY_REG;
        writel(__pa_symbol(sunxi_mc_smp_secondary_startup), addr);

        /* Actually enable multi cluster SMP */
        smp_set_ops(&sunxi_mc_smp_smp_ops);

        pr_info("sunxi multi cluster SMP support installed\n");

        return 0;

err_unmap_release_sram_rcpucfg:
        if (is_a83t) {
                iounmap(r_cpucfg_base);
                of_address_to_resource(nodes.r_cpucfg_node, 0, &res);
        } else {
                iounmap(sram_b_smp_base);
                of_address_to_resource(nodes.sram_node, 0, &res);
        }
        release_mem_region(res.start, resource_size(&res));
err_unmap_release_cpucfg:
        iounmap(cpucfg_base);
        of_address_to_resource(nodes.cpucfg_node, 0, &res);
        release_mem_region(res.start, resource_size(&res));
err_unmap_prcm:
        iounmap(prcm_base);
err_put_nodes:
        sunxi_mc_smp_put_nodes(&nodes);
        return ret;
}

early_initcall(sunxi_mc_smp_init);