/*
 * Copyright (c) 2013 MundoReader S.L.
 * Author: Heiko Stuebner <heiko@sntech.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that 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.
 */

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>

#include <linux/reset.h>
#include <linux/cpu.h>
#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/smp_scu.h>
#include <asm/smp_plat.h>
#include <asm/mach/map.h>

#include "core.h"

static void __iomem *scu_base_addr;
static void __iomem *sram_base_addr;
static int ncores;

#define PMU_PWRDN_CON           0x08
#define PMU_PWRDN_ST            0x0c

#define PMU_PWRDN_SCU           4

static struct regmap *pmu;
static int has_pmu = true;

static int pmu_power_domain_is_on(int pd)
{
        u32 val;
        int ret;

        ret = regmap_read(pmu, PMU_PWRDN_ST, &val);
        if (ret < 0)
                return ret;

        return !(val & BIT(pd));
}

static struct reset_control *rockchip_get_core_reset(int cpu)
{
        struct device *dev = get_cpu_device(cpu);
        struct device_node *np;

        /* The cpu device is only available after the initial core bringup */
        if (dev)
                np = dev->of_node;
        else
                np = of_get_cpu_node(cpu, NULL);

        return of_reset_control_get_exclusive(np, NULL);
}

static int pmu_set_power_domain(int pd, bool on)
{
        u32 val = (on) ? 0 : BIT(pd);
        struct reset_control *rstc = rockchip_get_core_reset(pd);
        int ret;

        if (IS_ERR(rstc) && read_cpuid_part() != ARM_CPU_PART_CORTEX_A9) {
                pr_err("%s: could not get reset control for core %d\n",
                       __func__, pd);
                return PTR_ERR(rstc);
        }

        /*
         * We need to soft reset the cpu when we turn off the cpu power domain,
         * or else the active processors might be stalled when the individual
         * processor is powered down.
         */
        if (!IS_ERR(rstc) && !on)
                reset_control_assert(rstc);

        if (has_pmu) {
                ret = regmap_update_bits(pmu, PMU_PWRDN_CON, BIT(pd), val);
                if (ret < 0) {
                        pr_err("%s: could not update power domain\n",
                               __func__);
                        return ret;
                }

                ret = -1;
                while (ret != on) {
                        ret = pmu_power_domain_is_on(pd);
                        if (ret < 0) {
                                pr_err("%s: could not read power domain state\n",
                                       __func__);
                                return ret;
                        }
                }
        }

        if (!IS_ERR(rstc)) {
                if (on)
                        reset_control_deassert(rstc);
                reset_control_put(rstc);
        }

        return 0;
}

/*
 * Handling of CPU cores
 */

static int rockchip_boot_secondary(unsigned int cpu, struct task_struct *idle)
{
        int ret;

        if (!sram_base_addr || (has_pmu && !pmu)) {
                pr_err("%s: sram or pmu missing for cpu boot\n", __func__);
                return -ENXIO;
        }

        if (cpu >= ncores) {
                pr_err("%s: cpu %d outside maximum number of cpus %d\n",
                       __func__, cpu, ncores);
                return -ENXIO;
        }

        /* start the core */
        ret = pmu_set_power_domain(0 + cpu, true);
        if (ret < 0)
                return ret;

        if (read_cpuid_part() != ARM_CPU_PART_CORTEX_A9) {
                /*
                 * We communicate with the bootrom to active the cpus other
                 * than cpu0, after a blob of initialize code, they will
                 * stay at wfe state, once they are actived, they will check
                 * the mailbox:
                 * sram_base_addr + 4: 0xdeadbeaf
                 * sram_base_addr + 8: start address for pc
                 * The cpu0 need to wait the other cpus other than cpu0 entering
                 * the wfe state.The wait time is affected by many aspects.
                 * (e.g: cpu frequency, bootrom frequency, sram frequency, ...)
                 */
                mdelay(1); /* ensure the cpus other than cpu0 to startup */

                writel(__pa_symbol(secondary_startup), sram_base_addr + 8);
                writel(0xDEADBEAF, sram_base_addr + 4);
                dsb_sev();
        }

        return 0;
}

/**
 * rockchip_smp_prepare_sram - populate necessary sram block
 * Starting cores execute the code residing at the start of the on-chip sram
 * after power-on. Therefore make sure, this sram region is reserved and
 * big enough. After this check, copy the trampoline code that directs the
 * core to the real startup code in ram into the sram-region.
 * @node: mmio-sram device node
 */
static int __init rockchip_smp_prepare_sram(struct device_node *node)
{
        unsigned int trampoline_sz = &rockchip_secondary_trampoline_end -
                                            &rockchip_secondary_trampoline;
        struct resource res;
        unsigned int rsize;
        int ret;

        ret = of_address_to_resource(node, 0, &res);
        if (ret < 0) {
                pr_err("%s: could not get address for node %pOF\n",
                       __func__, node);
                return ret;
        }

        rsize = resource_size(&res);
        if (rsize < trampoline_sz) {
                pr_err("%s: reserved block with size 0x%x is to small for trampoline size 0x%x\n",
                       __func__, rsize, trampoline_sz);
                return -EINVAL;
        }

        /* set the boot function for the sram code */
        rockchip_boot_fn = __pa_symbol(secondary_startup);

        /* copy the trampoline to sram, that runs during startup of the core */
        memcpy(sram_base_addr, &rockchip_secondary_trampoline, trampoline_sz);
        flush_cache_all();
        outer_clean_range(0, trampoline_sz);

        dsb_sev();

        return 0;
}

static const struct regmap_config rockchip_pmu_regmap_config = {
        .name = "rockchip-pmu",
        .reg_bits = 32,
        .val_bits = 32,
        .reg_stride = 4,
};

static int __init rockchip_smp_prepare_pmu(void)
{
        struct device_node *node;
        void __iomem *pmu_base;

        /*
         * This function is only called via smp_ops->smp_prepare_cpu().
         * That only happens if a "/cpus" device tree node exists
         * and has an "enable-method" property that selects the SMP
         * operations defined herein.
         */
        node = of_find_node_by_path("/cpus");

        pmu = syscon_regmap_lookup_by_phandle(node, "rockchip,pmu");
        of_node_put(node);
        if (!IS_ERR(pmu))
                return 0;

        pmu = syscon_regmap_lookup_by_compatible("rockchip,rk3066-pmu");
        if (!IS_ERR(pmu))
                return 0;

        /* fallback, create our own regmap for the pmu area */
        pmu = NULL;
        node = of_find_compatible_node(NULL, NULL, "rockchip,rk3066-pmu");
        if (!node) {
                pr_err("%s: could not find pmu dt node\n", __func__);
                return -ENODEV;
        }

        pmu_base = of_iomap(node, 0);
        if (!pmu_base) {
                pr_err("%s: could not map pmu registers\n", __func__);
                return -ENOMEM;
        }

        pmu = regmap_init_mmio(NULL, pmu_base, &rockchip_pmu_regmap_config);
        if (IS_ERR(pmu)) {
                int ret = PTR_ERR(pmu);

                iounmap(pmu_base);
                pmu = NULL;
                pr_err("%s: regmap init failed\n", __func__);
                return ret;
        }

        return 0;
}

static void __init rockchip_smp_prepare_cpus(unsigned int max_cpus)
{
        struct device_node *node;
        unsigned int i;

        node = of_find_compatible_node(NULL, NULL, "rockchip,rk3066-smp-sram");
        if (!node) {
                pr_err("%s: could not find sram dt node\n", __func__);
                return;
        }

        sram_base_addr = of_iomap(node, 0);
        if (!sram_base_addr) {
                pr_err("%s: could not map sram registers\n", __func__);
                return;
        }

        if (has_pmu && rockchip_smp_prepare_pmu())
                return;

        if (read_cpuid_part() == ARM_CPU_PART_CORTEX_A9) {
                if (rockchip_smp_prepare_sram(node))
                        return;

                /* enable the SCU power domain */
                pmu_set_power_domain(PMU_PWRDN_SCU, true);

                node = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
                if (!node) {
                        pr_err("%s: missing scu\n", __func__);
                        return;
                }

                scu_base_addr = of_iomap(node, 0);
                if (!scu_base_addr) {
                        pr_err("%s: could not map scu registers\n", __func__);
                        return;
                }

                /*
                 * While the number of cpus is gathered from dt, also get the
                 * number of cores from the scu to verify this value when
                 * booting the cores.
                 */
                ncores = scu_get_core_count(scu_base_addr);
                pr_err("%s: ncores %d\n", __func__, ncores);

                scu_enable(scu_base_addr);
        } else {
                unsigned int l2ctlr;

                asm ("mrc p15, 1, %0, c9, c0, 2\n" : "=r" (l2ctlr));
                ncores = ((l2ctlr >> 24) & 0x3) + 1;
        }

        /* Make sure that all cores except the first are really off */
        for (i = 1; i < ncores; i++)
                pmu_set_power_domain(0 + i, false);
}

static void __init rk3036_smp_prepare_cpus(unsigned int max_cpus)
{
        has_pmu = false;

        rockchip_smp_prepare_cpus(max_cpus);
}

#ifdef CONFIG_HOTPLUG_CPU
static int rockchip_cpu_kill(unsigned int cpu)
{
        /*
         * We need a delay here to ensure that the dying CPU can finish
         * executing v7_coherency_exit() and reach the WFI/WFE state
         * prior to having the power domain disabled.
         */
        mdelay(1);

        pmu_set_power_domain(0 + cpu, false);
        return 1;
}

static void rockchip_cpu_die(unsigned int cpu)
{
        v7_exit_coherency_flush(louis);
        while (1)
                cpu_do_idle();
}
#endif

static const struct smp_operations rk3036_smp_ops __initconst = {
        .smp_prepare_cpus       = rk3036_smp_prepare_cpus,
        .smp_boot_secondary     = rockchip_boot_secondary,
#ifdef CONFIG_HOTPLUG_CPU
        .cpu_kill               = rockchip_cpu_kill,
        .cpu_die                = rockchip_cpu_die,
#endif
};

static const struct smp_operations rockchip_smp_ops __initconst = {
        .smp_prepare_cpus       = rockchip_smp_prepare_cpus,
        .smp_boot_secondary     = rockchip_boot_secondary,
#ifdef CONFIG_HOTPLUG_CPU
        .cpu_kill               = rockchip_cpu_kill,
        .cpu_die                = rockchip_cpu_die,
#endif
};

CPU_METHOD_OF_DECLARE(rk3036_smp, "rockchip,rk3036-smp", &rk3036_smp_ops);
CPU_METHOD_OF_DECLARE(rk3066_smp, "rockchip,rk3066-smp", &rockchip_smp_ops);