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/*
* 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>
/*
* 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 *)¤t_thread_info()->flags);
__monitor((void *)¤t_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);
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