/*
 *  cpuidle-powernv - idle state cpuidle driver.
 *  Adapted from drivers/cpuidle/cpuidle-pseries
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/cpuidle.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/clockchips.h>
#include <linux/of.h>
#include <linux/slab.h>

#include <asm/machdep.h>
#include <asm/firmware.h>
#include <asm/opal.h>
#include <asm/runlatch.h>

#define MAX_POWERNV_IDLE_STATES 8

struct cpuidle_driver powernv_idle_driver = {
        .name             = "powernv_idle",
        .owner            = THIS_MODULE,
};

static int max_idle_state;
static struct cpuidle_state *cpuidle_state_table;
static u64 snooze_timeout;
static bool snooze_timeout_en;

static int snooze_loop(struct cpuidle_device *dev,
                        struct cpuidle_driver *drv,
                        int index)
{
        u64 snooze_exit_time;

        local_irq_enable();
        set_thread_flag(TIF_POLLING_NRFLAG);

        snooze_exit_time = get_tb() + snooze_timeout;
        ppc64_runlatch_off();
        while (!need_resched()) {
                HMT_low();
                HMT_very_low();
                if (snooze_timeout_en && get_tb() > snooze_exit_time)
                        break;
        }

        HMT_medium();
        ppc64_runlatch_on();
        clear_thread_flag(TIF_POLLING_NRFLAG);
        smp_mb();
        return index;
}

static int nap_loop(struct cpuidle_device *dev,
                        struct cpuidle_driver *drv,
                        int index)
{
        ppc64_runlatch_off();
        power7_idle();
        ppc64_runlatch_on();
        return index;
}

/* Register for fastsleep only in oneshot mode of broadcast */
#ifdef CONFIG_TICK_ONESHOT
static int fastsleep_loop(struct cpuidle_device *dev,
                                struct cpuidle_driver *drv,
                                int index)
{
        unsigned long old_lpcr = mfspr(SPRN_LPCR);
        unsigned long new_lpcr;

        if (unlikely(system_state < SYSTEM_RUNNING))
                return index;

        new_lpcr = old_lpcr;
        /* Do not exit powersave upon decrementer as we've setup the timer
         * offload.
         */
        new_lpcr &= ~LPCR_PECE1;

        mtspr(SPRN_LPCR, new_lpcr);
        power7_sleep();

        mtspr(SPRN_LPCR, old_lpcr);

        return index;
}
#endif
/*
 * States for dedicated partition case.
 */
static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
        { /* Snooze */
                .name = "snooze",
                .desc = "snooze",
                .exit_latency = 0,
                .target_residency = 0,
                .enter = &snooze_loop },
};

static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
                        unsigned long action, void *hcpu)
{
        int hotcpu = (unsigned long)hcpu;
        struct cpuidle_device *dev =
                                per_cpu(cpuidle_devices, hotcpu);

        if (dev && cpuidle_get_driver()) {
                switch (action) {
                case CPU_ONLINE:
                case CPU_ONLINE_FROZEN:
                        cpuidle_pause_and_lock();
                        cpuidle_enable_device(dev);
                        cpuidle_resume_and_unlock();
                        break;

                case CPU_DEAD:
                case CPU_DEAD_FROZEN:
                        cpuidle_pause_and_lock();
                        cpuidle_disable_device(dev);
                        cpuidle_resume_and_unlock();
                        break;

                default:
                        return NOTIFY_DONE;
                }
        }
        return NOTIFY_OK;
}

static struct notifier_block setup_hotplug_notifier = {
        .notifier_call = powernv_cpuidle_add_cpu_notifier,
};

/*
 * powernv_cpuidle_driver_init()
 */
static int powernv_cpuidle_driver_init(void)
{
        int idle_state;
        struct cpuidle_driver *drv = &powernv_idle_driver;

        drv->state_count = 0;

        for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
                /* Is the state not enabled? */
                if (cpuidle_state_table[idle_state].enter == NULL)
                        continue;

                drv->states[drv->state_count] = /* structure copy */
                        cpuidle_state_table[idle_state];

                drv->state_count += 1;
        }

        return 0;
}

static int powernv_add_idle_states(void)
{
        struct device_node *power_mgt;
        int nr_idle_states = 1; /* Snooze */
        int dt_idle_states;
        u32 *latency_ns, *residency_ns, *flags;
        int i, rc;

        /* Currently we have snooze statically defined */

        power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
        if (!power_mgt) {
                pr_warn("opal: PowerMgmt Node not found\n");
                goto out;
        }

        /* Read values of any property to determine the num of idle states */
        dt_idle_states = of_property_count_u32_elems(power_mgt, "ibm,cpu-idle-state-flags");
        if (dt_idle_states < 0) {
                pr_warn("cpuidle-powernv: no idle states found in the DT\n");
                goto out;
        }

        flags = kzalloc(sizeof(*flags) * dt_idle_states, GFP_KERNEL);
        if (of_property_read_u32_array(power_mgt,
                        "ibm,cpu-idle-state-flags", flags, dt_idle_states)) {
                pr_warn("cpuidle-powernv : missing ibm,cpu-idle-state-flags in DT\n");
                goto out_free_flags;
        }

        latency_ns = kzalloc(sizeof(*latency_ns) * dt_idle_states, GFP_KERNEL);
        rc = of_property_read_u32_array(power_mgt,
                "ibm,cpu-idle-state-latencies-ns", latency_ns, dt_idle_states);
        if (rc) {
                pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT\n");
                goto out_free_latency;
        }

        residency_ns = kzalloc(sizeof(*residency_ns) * dt_idle_states, GFP_KERNEL);
        rc = of_property_read_u32_array(power_mgt,
                "ibm,cpu-idle-state-residency-ns", residency_ns, dt_idle_states);

        for (i = 0; i < dt_idle_states; i++) {

                /*
                 * Cpuidle accepts exit_latency and target_residency in us.
                 * Use default target_residency values if f/w does not expose it.
                 */
                if (flags[i] & OPAL_PM_NAP_ENABLED) {
                        /* Add NAP state */
                        strcpy(powernv_states[nr_idle_states].name, "Nap");
                        strcpy(powernv_states[nr_idle_states].desc, "Nap");
                        powernv_states[nr_idle_states].flags = 0;
                        powernv_states[nr_idle_states].target_residency = 100;
                        powernv_states[nr_idle_states].enter = &nap_loop;
                }

                /*
                 * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
                 * within this config dependency check.
                 */
#ifdef CONFIG_TICK_ONESHOT
                if (flags[i] & OPAL_PM_SLEEP_ENABLED ||
                        flags[i] & OPAL_PM_SLEEP_ENABLED_ER1) {
                        /* Add FASTSLEEP state */
                        strcpy(powernv_states[nr_idle_states].name, "FastSleep");
                        strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
                        powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIMER_STOP;
                        powernv_states[nr_idle_states].target_residency = 300000;
                        powernv_states[nr_idle_states].enter = &fastsleep_loop;
                }
#endif
                powernv_states[nr_idle_states].exit_latency =
                                ((unsigned int)latency_ns[i]) / 1000;

                if (!rc) {
                        powernv_states[nr_idle_states].target_residency =
                                ((unsigned int)residency_ns[i]) / 1000;
                }

                nr_idle_states++;
        }

        kfree(residency_ns);
out_free_latency:
        kfree(latency_ns);
out_free_flags:
        kfree(flags);
out:
        return nr_idle_states;
}

/*
 * powernv_idle_probe()
 * Choose state table for shared versus dedicated partition
 */
static int powernv_idle_probe(void)
{
        if (cpuidle_disable != IDLE_NO_OVERRIDE)
                return -ENODEV;

        if (firmware_has_feature(FW_FEATURE_OPAL)) {
                cpuidle_state_table = powernv_states;
                /* Device tree can indicate more idle states */
                max_idle_state = powernv_add_idle_states();
                if (max_idle_state > 1) {
                        snooze_timeout_en = true;
                        snooze_timeout = powernv_states[1].target_residency *
                                         tb_ticks_per_usec;
                }
        } else
                return -ENODEV;

        return 0;
}

static int __init powernv_processor_idle_init(void)
{
        int retval;

        retval = powernv_idle_probe();
        if (retval)
                return retval;

        powernv_cpuidle_driver_init();
        retval = cpuidle_register(&powernv_idle_driver, NULL);
        if (retval) {
                printk(KERN_DEBUG "Registration of powernv driver failed.\n");
                return retval;
        }

        register_cpu_notifier(&setup_hotplug_notifier);
        printk(KERN_DEBUG "powernv_idle_driver registered\n");
        return 0;
}

device_initcall(powernv_processor_idle_init);