/*
 * Thermal throttle event support code (such as syslog messaging and rate
 * limiting) that was factored out from x86_64 (mce_intel.c) and i386 (p4.c).
 *
 * This allows consistent reporting of CPU thermal throttle events.
 *
 * Maintains a counter in /sys that keeps track of the number of thermal
 * events, such that the user knows how bad the thermal problem might be
 * (since the logging to syslog and mcelog is rate limited).
 *
 * Author: Dmitriy Zavin (dmitriyz@google.com)
 *
 * Credits: Adapted from Zwane Mwaikambo's original code in mce_intel.c.
 *          Inspired by Ross Biro's and Al Borchers' counter code.
 */
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/percpu.h>
#include <linux/sysdev.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/cpu.h>

#include <asm/processor.h>
#include <asm/system.h>
#include <asm/apic.h>
#include <asm/idle.h>
#include <asm/mce.h>
#include <asm/msr.h>

/* How long to wait between reporting thermal events */
#define CHECK_INTERVAL          (300 * HZ)

/*
 * Current thermal throttling state:
 */
struct thermal_state {
        bool                    is_throttled;

        u64                     next_check;
        unsigned long           throttle_count;
        unsigned long           last_throttle_count;
};

static DEFINE_PER_CPU(struct thermal_state, thermal_state);

static atomic_t therm_throt_en  = ATOMIC_INIT(0);

#ifdef CONFIG_SYSFS
#define define_therm_throt_sysdev_one_ro(_name)                         \
        static SYSDEV_ATTR(_name, 0444, therm_throt_sysdev_show_##_name, NULL)

#define define_therm_throt_sysdev_show_func(name)                       \
                                                                        \
static ssize_t therm_throt_sysdev_show_##name(                          \
                        struct sys_device *dev,                         \
                        struct sysdev_attribute *attr,                  \
                        char *buf)                                      \
{                                                                       \
        unsigned int cpu = dev->id;                                     \
        ssize_t ret;                                                    \
                                                                        \
        preempt_disable();      /* CPU hotplug */                       \
        if (cpu_online(cpu))                                            \
                ret = sprintf(buf, "%lu\n",                             \
                              per_cpu(thermal_state, cpu).name);        \
        else                                                            \
                ret = 0;                                                \
        preempt_enable();                                               \
                                                                        \
        return ret;                                                     \
}

define_therm_throt_sysdev_show_func(throttle_count);
define_therm_throt_sysdev_one_ro(throttle_count);

static struct attribute *thermal_throttle_attrs[] = {
        &attr_throttle_count.attr,
        NULL
};

static struct attribute_group thermal_throttle_attr_group = {
        .attrs  = thermal_throttle_attrs,
        .name   = "thermal_throttle"
};
#endif /* CONFIG_SYSFS */

/***
 * therm_throt_process - Process thermal throttling event from interrupt
 * @curr: Whether the condition is current or not (boolean), since the
 *        thermal interrupt normally gets called both when the thermal
 *        event begins and once the event has ended.
 *
 * This function is called by the thermal interrupt after the
 * IRQ has been acknowledged.
 *
 * It will take care of rate limiting and printing messages to the syslog.
 *
 * Returns: 0 : Event should NOT be further logged, i.e. still in
 *              "timeout" from previous log message.
 *          1 : Event should be logged further, and a message has been
 *              printed to the syslog.
 */
static int therm_throt_process(bool is_throttled)
{
        struct thermal_state *state;
        unsigned int this_cpu;
        bool was_throttled;
        u64 now;

        this_cpu = smp_processor_id();
        now = get_jiffies_64();
        state = &per_cpu(thermal_state, this_cpu);

        was_throttled = state->is_throttled;
        state->is_throttled = is_throttled;

        if (is_throttled)
                state->throttle_count++;

        if (time_before64(now, state->next_check) &&
                        state->throttle_count != state->last_throttle_count)
                return 0;

        state->next_check = now + CHECK_INTERVAL;
        state->last_throttle_count = state->throttle_count;

        /* if we just entered the thermal event */
        if (is_throttled) {
                printk(KERN_CRIT "CPU%d: Temperature above threshold, cpu clock throttled (total events = %lu)\n", this_cpu, state->throttle_count);

                add_taint(TAINT_MACHINE_CHECK);
                return 1;
        }
        if (was_throttled) {
                printk(KERN_INFO "CPU%d: Temperature/speed normal\n", this_cpu);
                return 1;
        }

        return 0;
}

#ifdef CONFIG_SYSFS
/* Add/Remove thermal_throttle interface for CPU device: */
static __cpuinit int thermal_throttle_add_dev(struct sys_device *sys_dev)
{
        return sysfs_create_group(&sys_dev->kobj,
                                  &thermal_throttle_attr_group);
}

static __cpuinit void thermal_throttle_remove_dev(struct sys_device *sys_dev)
{
        sysfs_remove_group(&sys_dev->kobj, &thermal_throttle_attr_group);
}

/* Mutex protecting device creation against CPU hotplug: */
static DEFINE_MUTEX(therm_cpu_lock);

/* Get notified when a cpu comes on/off. Be hotplug friendly. */
static __cpuinit int
thermal_throttle_cpu_callback(struct notifier_block *nfb,
                              unsigned long action,
                              void *hcpu)
{
        unsigned int cpu = (unsigned long)hcpu;
        struct sys_device *sys_dev;
        int err = 0;

        sys_dev = get_cpu_sysdev(cpu);

        switch (action) {
        case CPU_UP_PREPARE:
        case CPU_UP_PREPARE_FROZEN:
                mutex_lock(&therm_cpu_lock);
                err = thermal_throttle_add_dev(sys_dev);
                mutex_unlock(&therm_cpu_lock);
                WARN_ON(err);
                break;
        case CPU_UP_CANCELED:
        case CPU_UP_CANCELED_FROZEN:
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
                mutex_lock(&therm_cpu_lock);
                thermal_throttle_remove_dev(sys_dev);
                mutex_unlock(&therm_cpu_lock);
                break;
        }
        return err ? NOTIFY_BAD : NOTIFY_OK;
}

static struct notifier_block thermal_throttle_cpu_notifier __cpuinitdata =
{
        .notifier_call = thermal_throttle_cpu_callback,
};

static __init int thermal_throttle_init_device(void)
{
        unsigned int cpu = 0;
        int err;

        if (!atomic_read(&therm_throt_en))
                return 0;

        register_hotcpu_notifier(&thermal_throttle_cpu_notifier);

#ifdef CONFIG_HOTPLUG_CPU
        mutex_lock(&therm_cpu_lock);
#endif
        /* connect live CPUs to sysfs */
        for_each_online_cpu(cpu) {
                err = thermal_throttle_add_dev(get_cpu_sysdev(cpu));
                WARN_ON(err);
        }
#ifdef CONFIG_HOTPLUG_CPU
        mutex_unlock(&therm_cpu_lock);
#endif

        return 0;
}
device_initcall(thermal_throttle_init_device);

#endif /* CONFIG_SYSFS */

/* Thermal transition interrupt handler */
static void intel_thermal_interrupt(void)
{
        __u64 msr_val;

        rdmsrl(MSR_IA32_THERM_STATUS, msr_val);
        if (therm_throt_process((msr_val & THERM_STATUS_PROCHOT) != 0))
                mce_log_therm_throt_event(msr_val);
}

static void unexpected_thermal_interrupt(void)
{
        printk(KERN_ERR "CPU%d: Unexpected LVT TMR interrupt!\n",
                        smp_processor_id());
        add_taint(TAINT_MACHINE_CHECK);
}

static void (*smp_thermal_vector)(void) = unexpected_thermal_interrupt;

asmlinkage void smp_thermal_interrupt(struct pt_regs *regs)
{
        exit_idle();
        irq_enter();
        inc_irq_stat(irq_thermal_count);
        smp_thermal_vector();
        irq_exit();
        /* Ack only at the end to avoid potential reentry */
        ack_APIC_irq();
}

void intel_init_thermal(struct cpuinfo_x86 *c)
{
        unsigned int cpu = smp_processor_id();
        int tm2 = 0;
        u32 l, h;

        /* Thermal monitoring depends on ACPI and clock modulation*/
        if (!cpu_has(c, X86_FEATURE_ACPI) || !cpu_has(c, X86_FEATURE_ACC))
                return;

        /*
         * First check if its enabled already, in which case there might
         * be some SMM goo which handles it, so we can't even put a handler
         * since it might be delivered via SMI already:
         */
        rdmsr(MSR_IA32_MISC_ENABLE, l, h);
        h = apic_read(APIC_LVTTHMR);
        if ((l & MSR_IA32_MISC_ENABLE_TM1) && (h & APIC_DM_SMI)) {
                printk(KERN_DEBUG
                       "CPU%d: Thermal monitoring handled by SMI\n", cpu);
                return;
        }

        /* Check whether a vector already exists */
        if (h & APIC_VECTOR_MASK) {
                printk(KERN_DEBUG
                       "CPU%d: Thermal LVT vector (%#x) already installed\n",
                       cpu, (h & APIC_VECTOR_MASK));
                return;
        }

        /* early Pentium M models use different method for enabling TM2 */
        if (cpu_has(c, X86_FEATURE_TM2)) {
                if (c->x86 == 6 && (c->x86_model == 9 || c->x86_model == 13)) {
                        rdmsr(MSR_THERM2_CTL, l, h);
                        if (l & MSR_THERM2_CTL_TM_SELECT)
                                tm2 = 1;
                } else if (l & MSR_IA32_MISC_ENABLE_TM2)
                        tm2 = 1;
        }

        /* We'll mask the thermal vector in the lapic till we're ready: */
        h = THERMAL_APIC_VECTOR | APIC_DM_FIXED | APIC_LVT_MASKED;
        apic_write(APIC_LVTTHMR, h);

        rdmsr(MSR_IA32_THERM_INTERRUPT, l, h);
        wrmsr(MSR_IA32_THERM_INTERRUPT,
                l | (THERM_INT_LOW_ENABLE | THERM_INT_HIGH_ENABLE), h);

        smp_thermal_vector = intel_thermal_interrupt;

        rdmsr(MSR_IA32_MISC_ENABLE, l, h);
        wrmsr(MSR_IA32_MISC_ENABLE, l | MSR_IA32_MISC_ENABLE_TM1, h);

        /* Unmask the thermal vector: */
        l = apic_read(APIC_LVTTHMR);
        apic_write(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);

        printk(KERN_INFO "CPU%d: Thermal monitoring enabled (%s)\n",
               cpu, tm2 ? "TM2" : "TM1");

        /* enable thermal throttle processing */
        atomic_set(&therm_throt_en, 1);
}