/*
 * 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.
 *
 * 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.
 *
 * Copyright (C) 2015 ARM Limited
 */

#define pr_fmt(fmt) "psci: " fmt

#include <linux/arm-smccc.h>
#include <linux/errno.h>
#include <linux/linkage.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/printk.h>
#include <linux/psci.h>
#include <linux/reboot.h>
#include <linux/suspend.h>

#include <uapi/linux/psci.h>

#include <asm/cputype.h>
#include <asm/system_misc.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>

/*
 * While a 64-bit OS can make calls with SMC32 calling conventions, for some
 * calls it is necessary to use SMC64 to pass or return 64-bit values.
 * For such calls PSCI_FN_NATIVE(version, name) will choose the appropriate
 * (native-width) function ID.
 */
#ifdef CONFIG_64BIT
#define PSCI_FN_NATIVE(version, name)   PSCI_##version##_FN64_##name
#else
#define PSCI_FN_NATIVE(version, name)   PSCI_##version##_FN_##name
#endif

/*
 * The CPU any Trusted OS is resident on. The trusted OS may reject CPU_OFF
 * calls to its resident CPU, so we must avoid issuing those. We never migrate
 * a Trusted OS even if it claims to be capable of migration -- doing so will
 * require cooperation with a Trusted OS driver.
 */
static int resident_cpu = -1;

bool psci_tos_resident_on(int cpu)
{
        return cpu == resident_cpu;
}

struct psci_operations psci_ops;

typedef unsigned long (psci_fn)(unsigned long, unsigned long,
                                unsigned long, unsigned long);
static psci_fn *invoke_psci_fn;

enum psci_function {
        PSCI_FN_CPU_SUSPEND,
        PSCI_FN_CPU_ON,
        PSCI_FN_CPU_OFF,
        PSCI_FN_MIGRATE,
        PSCI_FN_MAX,
};

static u32 psci_function_id[PSCI_FN_MAX];

#define PSCI_0_2_POWER_STATE_MASK               \
                                (PSCI_0_2_POWER_STATE_ID_MASK | \
                                PSCI_0_2_POWER_STATE_TYPE_MASK | \
                                PSCI_0_2_POWER_STATE_AFFL_MASK)

#define PSCI_1_0_EXT_POWER_STATE_MASK           \
                                (PSCI_1_0_EXT_POWER_STATE_ID_MASK | \
                                PSCI_1_0_EXT_POWER_STATE_TYPE_MASK)

static u32 psci_cpu_suspend_feature;

static inline bool psci_has_ext_power_state(void)
{
        return psci_cpu_suspend_feature &
                                PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK;
}

bool psci_power_state_loses_context(u32 state)
{
        const u32 mask = psci_has_ext_power_state() ?
                                        PSCI_1_0_EXT_POWER_STATE_TYPE_MASK :
                                        PSCI_0_2_POWER_STATE_TYPE_MASK;

        return state & mask;
}

bool psci_power_state_is_valid(u32 state)
{
        const u32 valid_mask = psci_has_ext_power_state() ?
                               PSCI_1_0_EXT_POWER_STATE_MASK :
                               PSCI_0_2_POWER_STATE_MASK;

        return !(state & ~valid_mask);
}

static unsigned long __invoke_psci_fn_hvc(unsigned long function_id,
                        unsigned long arg0, unsigned long arg1,
                        unsigned long arg2)
{
        struct arm_smccc_res res;

        arm_smccc_hvc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
        return res.a0;
}

static unsigned long __invoke_psci_fn_smc(unsigned long function_id,
                        unsigned long arg0, unsigned long arg1,
                        unsigned long arg2)
{
        struct arm_smccc_res res;

        arm_smccc_smc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
        return res.a0;
}

static int psci_to_linux_errno(int errno)
{
        switch (errno) {
        case PSCI_RET_SUCCESS:
                return 0;
        case PSCI_RET_NOT_SUPPORTED:
                return -EOPNOTSUPP;
        case PSCI_RET_INVALID_PARAMS:
        case PSCI_RET_INVALID_ADDRESS:
                return -EINVAL;
        case PSCI_RET_DENIED:
                return -EPERM;
        };

        return -EINVAL;
}

static u32 psci_get_version(void)
{
        return invoke_psci_fn(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
}

static int psci_cpu_suspend(u32 state, unsigned long entry_point)
{
        int err;
        u32 fn;

        fn = psci_function_id[PSCI_FN_CPU_SUSPEND];
        err = invoke_psci_fn(fn, state, entry_point, 0);
        return psci_to_linux_errno(err);
}

static int psci_cpu_off(u32 state)
{
        int err;
        u32 fn;

        fn = psci_function_id[PSCI_FN_CPU_OFF];
        err = invoke_psci_fn(fn, state, 0, 0);
        return psci_to_linux_errno(err);
}

static int psci_cpu_on(unsigned long cpuid, unsigned long entry_point)
{
        int err;
        u32 fn;

        fn = psci_function_id[PSCI_FN_CPU_ON];
        err = invoke_psci_fn(fn, cpuid, entry_point, 0);
        return psci_to_linux_errno(err);
}

static int psci_migrate(unsigned long cpuid)
{
        int err;
        u32 fn;

        fn = psci_function_id[PSCI_FN_MIGRATE];
        err = invoke_psci_fn(fn, cpuid, 0, 0);
        return psci_to_linux_errno(err);
}

static int psci_affinity_info(unsigned long target_affinity,
                unsigned long lowest_affinity_level)
{
        return invoke_psci_fn(PSCI_FN_NATIVE(0_2, AFFINITY_INFO),
                              target_affinity, lowest_affinity_level, 0);
}

static int psci_migrate_info_type(void)
{
        return invoke_psci_fn(PSCI_0_2_FN_MIGRATE_INFO_TYPE, 0, 0, 0);
}

static unsigned long psci_migrate_info_up_cpu(void)
{
        return invoke_psci_fn(PSCI_FN_NATIVE(0_2, MIGRATE_INFO_UP_CPU),
                              0, 0, 0);
}

static int get_set_conduit_method(struct device_node *np)
{
        const char *method;

        pr_info("probing for conduit method from DT.\n");

        if (of_property_read_string(np, "method", &method)) {
                pr_warn("missing \"method\" property\n");
                return -ENXIO;
        }

        if (!strcmp("hvc", method)) {
                invoke_psci_fn = __invoke_psci_fn_hvc;
        } else if (!strcmp("smc", method)) {
                invoke_psci_fn = __invoke_psci_fn_smc;
        } else {
                pr_warn("invalid \"method\" property: %s\n", method);
                return -EINVAL;
        }
        return 0;
}

static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
{
        invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
}

static void psci_sys_poweroff(void)
{
        invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
}

static int __init psci_features(u32 psci_func_id)
{
        return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES,
                              psci_func_id, 0, 0);
}

static int psci_system_suspend(unsigned long unused)
{
        return invoke_psci_fn(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND),
                              virt_to_phys(cpu_resume), 0, 0);
}

static int psci_system_suspend_enter(suspend_state_t state)
{
        return cpu_suspend(0, psci_system_suspend);
}

static const struct platform_suspend_ops psci_suspend_ops = {
        .valid          = suspend_valid_only_mem,
        .enter          = psci_system_suspend_enter,
};

static void __init psci_init_system_suspend(void)
{
        int ret;

        if (!IS_ENABLED(CONFIG_SUSPEND))
                return;

        ret = psci_features(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND));

        if (ret != PSCI_RET_NOT_SUPPORTED)
                suspend_set_ops(&psci_suspend_ops);
}

static void __init psci_init_cpu_suspend(void)
{
        int feature = psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND]);

        if (feature != PSCI_RET_NOT_SUPPORTED)
                psci_cpu_suspend_feature = feature;
}

/*
 * Detect the presence of a resident Trusted OS which may cause CPU_OFF to
 * return DENIED (which would be fatal).
 */
static void __init psci_init_migrate(void)
{
        unsigned long cpuid;
        int type, cpu = -1;

        type = psci_ops.migrate_info_type();

        if (type == PSCI_0_2_TOS_MP) {
                pr_info("Trusted OS migration not required\n");
                return;
        }

        if (type == PSCI_RET_NOT_SUPPORTED) {
                pr_info("MIGRATE_INFO_TYPE not supported.\n");
                return;
        }

        if (type != PSCI_0_2_TOS_UP_MIGRATE &&
            type != PSCI_0_2_TOS_UP_NO_MIGRATE) {
                pr_err("MIGRATE_INFO_TYPE returned unknown type (%d)\n", type);
                return;
        }

        cpuid = psci_migrate_info_up_cpu();
        if (cpuid & ~MPIDR_HWID_BITMASK) {
                pr_warn("MIGRATE_INFO_UP_CPU reported invalid physical ID (0x%lx)\n",
                        cpuid);
                return;
        }

        cpu = get_logical_index(cpuid);
        resident_cpu = cpu >= 0 ? cpu : -1;

        pr_info("Trusted OS resident on physical CPU 0x%lx\n", cpuid);
}

static void __init psci_0_2_set_functions(void)
{
        pr_info("Using standard PSCI v0.2 function IDs\n");
        psci_function_id[PSCI_FN_CPU_SUSPEND] =
                                        PSCI_FN_NATIVE(0_2, CPU_SUSPEND);
        psci_ops.cpu_suspend = psci_cpu_suspend;

        psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF;
        psci_ops.cpu_off = psci_cpu_off;

        psci_function_id[PSCI_FN_CPU_ON] = PSCI_FN_NATIVE(0_2, CPU_ON);
        psci_ops.cpu_on = psci_cpu_on;

        psci_function_id[PSCI_FN_MIGRATE] = PSCI_FN_NATIVE(0_2, MIGRATE);
        psci_ops.migrate = psci_migrate;

        psci_ops.affinity_info = psci_affinity_info;

        psci_ops.migrate_info_type = psci_migrate_info_type;

        arm_pm_restart = psci_sys_reset;

        pm_power_off = psci_sys_poweroff;
}

/*
 * Probe function for PSCI firmware versions >= 0.2
 */
static int __init psci_probe(void)
{
        u32 ver = psci_get_version();

        pr_info("PSCIv%d.%d detected in firmware.\n",
                        PSCI_VERSION_MAJOR(ver),
                        PSCI_VERSION_MINOR(ver));

        if (PSCI_VERSION_MAJOR(ver) == 0 && PSCI_VERSION_MINOR(ver) < 2) {
                pr_err("Conflicting PSCI version detected.\n");
                return -EINVAL;
        }

        psci_0_2_set_functions();

        psci_init_migrate();

        if (PSCI_VERSION_MAJOR(ver) >= 1) {
                psci_init_cpu_suspend();
                psci_init_system_suspend();
        }

        return 0;
}

typedef int (*psci_initcall_t)(const struct device_node *);

/*
 * PSCI init function for PSCI versions >=0.2
 *
 * Probe based on PSCI PSCI_VERSION function
 */
static int __init psci_0_2_init(struct device_node *np)
{
        int err;

        err = get_set_conduit_method(np);

        if (err)
                goto out_put_node;
        /*
         * Starting with v0.2, the PSCI specification introduced a call
         * (PSCI_VERSION) that allows probing the firmware version, so
         * that PSCI function IDs and version specific initialization
         * can be carried out according to the specific version reported
         * by firmware
         */
        err = psci_probe();

out_put_node:
        of_node_put(np);
        return err;
}

/*
 * PSCI < v0.2 get PSCI Function IDs via DT.
 */
static int __init psci_0_1_init(struct device_node *np)
{
        u32 id;
        int err;

        err = get_set_conduit_method(np);

        if (err)
                goto out_put_node;

        pr_info("Using PSCI v0.1 Function IDs from DT\n");

        if (!of_property_read_u32(np, "cpu_suspend", &id)) {
                psci_function_id[PSCI_FN_CPU_SUSPEND] = id;
                psci_ops.cpu_suspend = psci_cpu_suspend;
        }

        if (!of_property_read_u32(np, "cpu_off", &id)) {
                psci_function_id[PSCI_FN_CPU_OFF] = id;
                psci_ops.cpu_off = psci_cpu_off;
        }

        if (!of_property_read_u32(np, "cpu_on", &id)) {
                psci_function_id[PSCI_FN_CPU_ON] = id;
                psci_ops.cpu_on = psci_cpu_on;
        }

        if (!of_property_read_u32(np, "migrate", &id)) {
                psci_function_id[PSCI_FN_MIGRATE] = id;
                psci_ops.migrate = psci_migrate;
        }

out_put_node:
        of_node_put(np);
        return err;
}

static const struct of_device_id const psci_of_match[] __initconst = {
        { .compatible = "arm,psci",     .data = psci_0_1_init},
        { .compatible = "arm,psci-0.2", .data = psci_0_2_init},
        { .compatible = "arm,psci-1.0", .data = psci_0_2_init},
        {},
};

int __init psci_dt_init(void)
{
        struct device_node *np;
        const struct of_device_id *matched_np;
        psci_initcall_t init_fn;

        np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);

        if (!np)
                return -ENODEV;

        init_fn = (psci_initcall_t)matched_np->data;
        return init_fn(np);
}

#ifdef CONFIG_ACPI
/*
 * We use PSCI 0.2+ when ACPI is deployed on ARM64 and it's
 * explicitly clarified in SBBR
 */
int __init psci_acpi_init(void)
{
        if (!acpi_psci_present()) {
                pr_info("is not implemented in ACPI.\n");
                return -EOPNOTSUPP;
        }

        pr_info("probing for conduit method from ACPI.\n");

        if (acpi_psci_use_hvc())
                invoke_psci_fn = __invoke_psci_fn_hvc;
        else
                invoke_psci_fn = __invoke_psci_fn_smc;

        return psci_probe();
}
#endif