/*
 * Copyright (C) 2005 Intel Corporation
 *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
 *      - Added _PDC for SMP C-states on Intel CPUs
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/cpu.h>
#include <linux/sched.h>

#include <acpi/processor.h>
#include <asm/acpi.h>
#include <asm/mwait.h>
#include <asm/special_insns.h>

/*
 * Initialize bm_flags based on the CPU cache properties
 * On SMP it depends on cache configuration
 * - When cache is not shared among all CPUs, we flush cache
 *   before entering C3.
 * - When cache is shared among all CPUs, we use bm_check
 *   mechanism as in UP case
 *
 * This routine is called only after all the CPUs are online
 */
void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
                                        unsigned int cpu)
{
        struct cpuinfo_x86 *c = &cpu_data(cpu);

        flags->bm_check = 0;
        if (num_online_cpus() == 1)
                flags->bm_check = 1;
        else if (c->x86_vendor == X86_VENDOR_INTEL) {
                /*
                 * Today all MP CPUs that support C3 share cache.
                 * And caches should not be flushed by software while
                 * entering C3 type state.
                 */
                flags->bm_check = 1;
        }

        /*
         * On all recent Intel platforms, ARB_DISABLE is a nop.
         * So, set bm_control to zero to indicate that ARB_DISABLE
         * is not required while entering C3 type state on
         * P4, Core and beyond CPUs
         */
        if (c->x86_vendor == X86_VENDOR_INTEL &&
            (c->x86 > 0xf || (c->x86 == 6 && c->x86_model >= 0x0f)))
                        flags->bm_control = 0;
}
EXPORT_SYMBOL(acpi_processor_power_init_bm_check);

/* The code below handles cstate entry with monitor-mwait pair on Intel*/

struct cstate_entry {
        struct {
                unsigned int eax;
                unsigned int ecx;
        } states[ACPI_PROCESSOR_MAX_POWER];
};
static struct cstate_entry __percpu *cpu_cstate_entry;  /* per CPU ptr */

static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];

#define NATIVE_CSTATE_BEYOND_HALT       (2)

static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
{
        struct acpi_processor_cx *cx = _cx;
        long retval;
        unsigned int eax, ebx, ecx, edx;
        unsigned int edx_part;
        unsigned int cstate_type; /* C-state type and not ACPI C-state type */
        unsigned int num_cstate_subtype;

        cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);

        /* Check whether this particular cx_type (in CST) is supported or not */
        cstate_type = ((cx->address >> MWAIT_SUBSTATE_SIZE) &
                        MWAIT_CSTATE_MASK) + 1;
        edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
        num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;

        retval = 0;
        if (num_cstate_subtype < (cx->address & MWAIT_SUBSTATE_MASK)) {
                retval = -1;
                goto out;
        }

        /* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
        if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
            !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
                retval = -1;
                goto out;
        }

        if (!mwait_supported[cstate_type]) {
                mwait_supported[cstate_type] = 1;
                printk(KERN_DEBUG
                        "Monitor-Mwait will be used to enter C-%d "
                        "state\n", cx->type);
        }
        snprintf(cx->desc,
                        ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
                        cx->address);
out:
        return retval;
}

int acpi_processor_ffh_cstate_probe(unsigned int cpu,
                struct acpi_processor_cx *cx, struct acpi_power_register *reg)
{
        struct cstate_entry *percpu_entry;
        struct cpuinfo_x86 *c = &cpu_data(cpu);
        long retval;

        if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF)
                return -1;

        if (reg->bit_offset != NATIVE_CSTATE_BEYOND_HALT)
                return -1;

        percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
        percpu_entry->states[cx->index].eax = 0;
        percpu_entry->states[cx->index].ecx = 0;

        /* Make sure we are running on right CPU */

        retval = work_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx);
        if (retval == 0) {
                /* Use the hint in CST */
                percpu_entry->states[cx->index].eax = cx->address;
                percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
        }

        /*
         * For _CST FFH on Intel, if GAS.access_size bit 1 is cleared,
         * then we should skip checking BM_STS for this C-state.
         * ref: "Intel Processor Vendor-Specific ACPI Interface Specification"
         */
        if ((c->x86_vendor == X86_VENDOR_INTEL) && !(reg->access_size & 0x2))
                cx->bm_sts_skip = 1;

        return retval;
}
EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);

/*
 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
 * which can obviate IPI to trigger checking of need_resched.
 * We execute MONITOR against need_resched and enter optimized wait state
 * through MWAIT. Whenever someone changes need_resched, we would be woken
 * up from MWAIT (without an IPI).
 *
 * New with Core Duo processors, MWAIT can take some hints based on CPU
 * capability.
 */
void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
{
        if (!need_resched()) {
                if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
                        clflush((void *)&current_thread_info()->flags);

                __monitor((void *)&current_thread_info()->flags, 0, 0);
                smp_mb();
                if (!need_resched())
                        __mwait(ax, cx);
        }
}

void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
{
        unsigned int cpu = smp_processor_id();
        struct cstate_entry *percpu_entry;

        percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
        mwait_idle_with_hints(percpu_entry->states[cx->index].eax,
                              percpu_entry->states[cx->index].ecx);
}
EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);

static int __init ffh_cstate_init(void)
{
        struct cpuinfo_x86 *c = &boot_cpu_data;
        if (c->x86_vendor != X86_VENDOR_INTEL)
                return -1;

        cpu_cstate_entry = alloc_percpu(struct cstate_entry);
        return 0;
}

static void __exit ffh_cstate_exit(void)
{
        free_percpu(cpu_cstate_entry);
        cpu_cstate_entry = NULL;
}

arch_initcall(ffh_cstate_init);
__exitcall(ffh_cstate_exit);