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ACPI: Processor native C-states using MWAIT

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Intel processors starting with the Core Duo support
support processor native C-state using the MWAIT instruction.
Refer: Intel Architecture Software Developer's Manual
http://www.intel.com/design/Pentium4/manuals/253668.htm

Platform firmware exports the support for Native C-state to OS using
ACPI _PDC and _CST methods.
Refer: Intel Processor Vendor-Specific ACPI: Interface Specification
http://www.intel.com/technology/iapc/acpi/downloads/302223.htm

With Processor Native C-state, we use 'MWAIT' instruction on the processor
to enter different C-states (C1, C2, C3).  We won't use the special IO
ports to enter C-state and no SMM mode etc required to enter C-state.
Overall this will mean better C-state support.

One major advantage of using MWAIT for all C-states is, with this and
"treat interrupt as break event" feature of MWAIT, we can now get accurate
timing for the time spent in C1, C2, ..  states.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Venkatesh Pallipadi
2006-09-25 16:28:13 -07:00
committed by Len Brown
parent b4bd8c6643
commit 991528d734
8 changed files with 242 additions and 56 deletions
Download Patch File Download Diff File Expand all files Collapse all files

97
drivers/acpi/processor_idle.c
View File

@@ -219,6 +219,23 @@ static void acpi_safe_halt(void)
static atomic_t c3_cpu_count;
/* Common C-state entry for C2, C3, .. */
static void acpi_cstate_enter(struct acpi_processor_cx *cstate)
{
if (cstate->space_id == ACPI_CSTATE_FFH) {
/* Call into architectural FFH based C-state */
acpi_processor_ffh_cstate_enter(cstate);
} else {
int unused;
/* IO port based C-state */
inb(cstate->address);
/* Dummy wait op - must do something useless after P_LVL2 read
because chipsets cannot guarantee that STPCLK# signal
gets asserted in time to freeze execution properly. */
unused = inl(acpi_fadt.xpm_tmr_blk.address);
}
}
static void acpi_processor_idle(void)
{
struct acpi_processor *pr = NULL;
@@ -361,11 +378,7 @@ static void acpi_processor_idle(void)
/* Get start time (ticks) */
t1 = inl(acpi_fadt.xpm_tmr_blk.address);
/* Invoke C2 */
inb(cx->address);
/* Dummy wait op - must do something useless after P_LVL2 read
because chipsets cannot guarantee that STPCLK# signal
gets asserted in time to freeze execution properly. */
t2 = inl(acpi_fadt.xpm_tmr_blk.address);
acpi_cstate_enter(cx);
/* Get end time (ticks) */
t2 = inl(acpi_fadt.xpm_tmr_blk.address);
@@ -401,9 +414,7 @@ static void acpi_processor_idle(void)
/* Get start time (ticks) */
t1 = inl(acpi_fadt.xpm_tmr_blk.address);
/* Invoke C3 */
inb(cx->address);
/* Dummy wait op (see above) */
t2 = inl(acpi_fadt.xpm_tmr_blk.address);
acpi_cstate_enter(cx);
/* Get end time (ticks) */
t2 = inl(acpi_fadt.xpm_tmr_blk.address);
if (pr->flags.bm_check) {
@@ -628,20 +639,16 @@ static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
return 0;
}
static int acpi_processor_get_power_info_default_c1(struct acpi_processor *pr)
static int acpi_processor_get_power_info_default(struct acpi_processor *pr)
{
/* Zero initialize all the C-states info. */
memset(pr->power.states, 0, sizeof(pr->power.states));
/* set the first C-State to C1 */
pr->power.states[ACPI_STATE_C1].type = ACPI_STATE_C1;
/* the C0 state only exists as a filler in our array,
* and all processors need to support C1 */
if (!pr->power.states[ACPI_STATE_C1].valid) {
/* set the first C-State to C1 */
/* all processors need to support C1 */
pr->power.states[ACPI_STATE_C1].type = ACPI_STATE_C1;
pr->power.states[ACPI_STATE_C1].valid = 1;
}
/* the C0 state only exists as a filler in our array */
pr->power.states[ACPI_STATE_C0].valid = 1;
pr->power.states[ACPI_STATE_C1].valid = 1;
return 0;
}
@@ -658,12 +665,7 @@ static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
if (nocst)
return -ENODEV;
current_count = 1;
/* Zero initialize C2 onwards and prepare for fresh CST lookup */
for (i = 2; i < ACPI_PROCESSOR_MAX_POWER; i++)
memset(&(pr->power.states[i]), 0,
sizeof(struct acpi_processor_cx));
current_count = 0;
status = acpi_evaluate_object(pr->handle, "_CST", NULL, &buffer);
if (ACPI_FAILURE(status)) {
@@ -718,22 +720,39 @@ static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
(reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE))
continue;
cx.address = (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) ?
0 : reg->address;
/* There should be an easy way to extract an integer... */
obj = (union acpi_object *)&(element->package.elements[1]);
if (obj->type != ACPI_TYPE_INTEGER)
continue;
cx.type = obj->integer.value;
/*
* Some buggy BIOSes won't list C1 in _CST -
* Let acpi_processor_get_power_info_default() handle them later
*/
if (i == 1 && cx.type != ACPI_STATE_C1)
current_count++;
if ((cx.type != ACPI_STATE_C1) &&
(reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO))
continue;
cx.address = reg->address;
cx.index = current_count + 1;
if ((cx.type < ACPI_STATE_C2) || (cx.type > ACPI_STATE_C3))
continue;
cx.space_id = ACPI_CSTATE_SYSTEMIO;
if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
if (acpi_processor_ffh_cstate_probe
(pr->id, &cx, reg) == 0) {
cx.space_id = ACPI_CSTATE_FFH;
} else if (cx.type != ACPI_STATE_C1) {
/*
* C1 is a special case where FIXED_HARDWARE
* can be handled in non-MWAIT way as well.
* In that case, save this _CST entry info.
* That is, we retain space_id of SYSTEM_IO for
* halt based C1.
* Otherwise, ignore this info and continue.
*/
continue;
}
}
obj = (union acpi_object *)&(element->package.elements[2]);
if (obj->type != ACPI_TYPE_INTEGER)
@@ -938,12 +957,18 @@ static int acpi_processor_get_power_info(struct acpi_processor *pr)
/* NOTE: the idle thread may not be running while calling
* this function */
/* Adding C1 state */
acpi_processor_get_power_info_default_c1(pr);
/* Zero initialize all the C-states info. */
memset(pr->power.states, 0, sizeof(pr->power.states));
result = acpi_processor_get_power_info_cst(pr);
if (result == -ENODEV)
acpi_processor_get_power_info_fadt(pr);
if (result)
return result;
acpi_processor_get_power_info_default(pr);
pr->power.count = acpi_processor_power_verify(pr);
/*