diff options
Diffstat (limited to 'arch/x86/kernel/acpi/cstate.c')
| -rw-r--r-- | arch/x86/kernel/acpi/cstate.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c new file mode 100644 index 00000000..d2b7f277 --- /dev/null +++ b/arch/x86/kernel/acpi/cstate.c @@ -0,0 +1,204 @@ +/* + * 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 *)¤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); |