diff mbox

[v5,2/5] ACPI / processor_idle: Add support for Low Power Idle(LPI) states

Message ID 1462981062-24909-3-git-send-email-sudeep.holla@arm.com (mailing list archive)
State Superseded, archived
Headers show

Commit Message

Sudeep Holla May 11, 2016, 3:37 p.m. UTC
ACPI 6.0 introduced an optional object _LPI that provides an alternate
method to describe Low Power Idle states. It defines the local power
states for each node in a hierarchical processor topology. The OSPM can
use _LPI object to select a local power state for each level of processor
hierarchy in the system. They used to produce a composite power state
request that is presented to the platform by the OSPM.

Since multiple processors affect the idle state for any non-leaf hierarchy
node, coordination of idle state requests between the processors is
required. ACPI supports two different coordination schemes: Platform
coordinated and  OS initiated.

This patch adds initial support for Platform coordination scheme of LPI.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/acpi/bus.c              |  14 +-
 drivers/acpi/processor_driver.c |   2 +-
 drivers/acpi/processor_idle.c   | 463 +++++++++++++++++++++++++++++++++++-----
 include/acpi/processor.h        |  24 ++-
 include/linux/acpi.h            |   4 +
 5 files changed, 447 insertions(+), 60 deletions(-)

Comments

Prakash, Prashanth May 17, 2016, 5:46 p.m. UTC | #1
Hi Sudeep,

On 5/11/2016 9:37 AM, Sudeep Holla wrote:
> +
> +static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
> +{
> +	int ret, i;
> +	struct acpi_lpi_states_array *info;
> +	struct acpi_device *d = NULL;
> +	acpi_handle handle = pr->handle, pr_ahandle;
> +	acpi_status status;
> +
> +	if (!osc_pc_lpi_support_confirmed)
> +		return -EOPNOTSUPP;
> +
> +	max_leaf_depth = 0;
> +	if (!acpi_has_method(handle, "_LPI"))
> +		return -EINVAL;
> +	flat_state_cnt = 0;
> +
> +	while (ACPI_SUCCESS(status = acpi_get_parent(handle, &pr_ahandle))) {
> +		if (!acpi_has_method(handle, "_LPI"))
> +			continue;
> +
> +		acpi_bus_get_device(handle, &d);
> +		if (!strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID))
> +			break;
> +
> +		max_leaf_depth++;
> +		handle = pr_ahandle;
> +	}
> +
In the above loop, we break when we find a device with HID == ACPI_PROCESSOR_CONTAINER_HID.
Shouldn't we continue to parse as long as the parent HID == ACPI_PROCESSOR_CONTAINER_HID?
This is required to make sure we parse states in levels higher than cluster level
in processor hierarchy.

Also, I think it might be safe to break out of the loop if we didn't find _LPI
package, instead of continuing. Given  the presence of LPI entry: "Enabled Parent
State", I can't think of a non-ambiguous scenario where we might find LPI packages
in state N and N+2, but not in N+1, as we will not be able to figure out which
state in N enables which states in N+2. Thoughts?

Thanks,
Prashanth
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Sudeep Holla May 18, 2016, 5:37 p.m. UTC | #2
On 17/05/16 18:46, Prakash, Prashanth wrote:
> Hi Sudeep,
>
> On 5/11/2016 9:37 AM, Sudeep Holla wrote:
>> +
>> +static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
>> +{
>> +	int ret, i;
>> +	struct acpi_lpi_states_array *info;
>> +	struct acpi_device *d = NULL;
>> +	acpi_handle handle = pr->handle, pr_ahandle;
>> +	acpi_status status;
>> +
>> +	if (!osc_pc_lpi_support_confirmed)
>> +		return -EOPNOTSUPP;
>> +
>> +	max_leaf_depth = 0;
>> +	if (!acpi_has_method(handle, "_LPI"))
>> +		return -EINVAL;
>> +	flat_state_cnt = 0;
>> +
>> +	while (ACPI_SUCCESS(status = acpi_get_parent(handle, &pr_ahandle))) {
>> +		if (!acpi_has_method(handle, "_LPI"))
>> +			continue;
>> +
>> +		acpi_bus_get_device(handle, &d);
>> +		if (!strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID))
>> +			break;
>> +
>> +		max_leaf_depth++;
>> +		handle = pr_ahandle;
>> +	}
>> +
> In the above loop, we break when we find a device with HID ==
> ACPI_PROCESSOR_CONTAINER_HID. Shouldn't we continue to parse as long as the
> parent HID == ACPI_PROCESSOR_CONTAINER_HID? This is required to make sure we
> parse states in levels higher than cluster level in processor hierarchy.
>

Yes, thanks for pointing that out. With just clusters in _LPI on my dev
board, I missed it.

> Also, I think it might be safe to break out of the loop if we didn't find
> _LPI package, instead of continuing. Given  the presence of LPI entry:
> "Enabled Parent State", I can't think of a non-ambiguous scenario where we
> might find LPI packages in state N and N+2, but not in N+1, as we will not
> be able to figure out which state in N enables which states in N+2.
> Thoughts?

Though I admit I haven't thought in detail on how to deal with the
asymmetric topology, but that was the reason why I continue instead of
breaking.

Excerpts from the spec: "... This example is symmetric but that is not a
requirement. For example, a system may contain a different number of
processors in different containers or an asymmetric hierarchy where one
side of the topology tree is deeper than another...."
Prakash, Prashanth May 18, 2016, 7:13 p.m. UTC | #3
On 5/18/2016 11:37 AM, Sudeep Holla wrote:
>
>
> On 17/05/16 18:46, Prakash, Prashanth wrote:
>> Hi Sudeep,
>>
>> On 5/11/2016 9:37 AM, Sudeep Holla wrote:
>>> +
>>> +static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
>>> +{
>>> +    int ret, i;
>>> +    struct acpi_lpi_states_array *info;
>>> +    struct acpi_device *d = NULL;
>>> +    acpi_handle handle = pr->handle, pr_ahandle;
>>> +    acpi_status status;
>>> +
>>> +    if (!osc_pc_lpi_support_confirmed)
>>> +        return -EOPNOTSUPP;
>>> +
>>> +    max_leaf_depth = 0;
>>> +    if (!acpi_has_method(handle, "_LPI"))
>>> +        return -EINVAL;
>>> +    flat_state_cnt = 0;
>>> +
>>> +    while (ACPI_SUCCESS(status = acpi_get_parent(handle, &pr_ahandle))) {
>>> +        if (!acpi_has_method(handle, "_LPI"))
>>> +            continue;
>>> +
>>> +        acpi_bus_get_device(handle, &d);
>>> +        if (!strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID))
>>> +            break;
>>> +
>>> +        max_leaf_depth++;
>>> +        handle = pr_ahandle;
>>> +    }
>>> +
>> In the above loop, we break when we find a device with HID ==
>> ACPI_PROCESSOR_CONTAINER_HID. Shouldn't we continue to parse as long as the
>> parent HID == ACPI_PROCESSOR_CONTAINER_HID? This is required to make sure we
>> parse states in levels higher than cluster level in processor hierarchy.
>>
>
> Yes, thanks for pointing that out. With just clusters in _LPI on my dev
> board, I missed it.
>
Same reason, I failed to notice it all this time :)
>> Also, I think it might be safe to break out of the loop if we didn't find
>> _LPI package, instead of continuing. Given  the presence of LPI entry:
>> "Enabled Parent State", I can't think of a non-ambiguous scenario where we
>> might find LPI packages in state N and N+2, but not in N+1, as we will not
>> be able to figure out which state in N enables which states in N+2.
>> Thoughts?
>
> Though I admit I haven't thought in detail on how to deal with the
> asymmetric topology, but that was the reason why I continue instead of
> breaking.
>
> Excerpts from the spec: "... This example is symmetric but that is not a
> requirement. For example, a system may contain a different number of
> processors in different containers or an asymmetric hierarchy where one
> side of the topology tree is deeper than another...."
>
If it addresses asymmetric topology, sure we can keep as it doesn't impact other
scenarios. Also, we need to set handle=pr_ahandle prior to the continue statement.


Thanks,
Prashanth
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Sudeep Holla May 19, 2016, 1:26 p.m. UTC | #4
On 18/05/16 20:13, Prakash, Prashanth wrote:
>
>
> On 5/18/2016 11:37 AM, Sudeep Holla wrote:
>>
>>
>> On 17/05/16 18:46, Prakash, Prashanth wrote:
>>> Hi Sudeep,
>>>
>>> On 5/11/2016 9:37 AM, Sudeep Holla wrote:
>>>> +
>>>> +static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
>>>> +{
>>>> +    int ret, i;
>>>> +    struct acpi_lpi_states_array *info;
>>>> +    struct acpi_device *d = NULL;
>>>> +    acpi_handle handle = pr->handle, pr_ahandle;
>>>> +    acpi_status status;
>>>> +
>>>> +    if (!osc_pc_lpi_support_confirmed)
>>>> +        return -EOPNOTSUPP;
>>>> +
>>>> +    max_leaf_depth = 0;
>>>> +    if (!acpi_has_method(handle, "_LPI"))
>>>> +        return -EINVAL;
>>>> +    flat_state_cnt = 0;
>>>> +
>>>> +    while (ACPI_SUCCESS(status = acpi_get_parent(handle, &pr_ahandle))) {
>>>> +        if (!acpi_has_method(handle, "_LPI"))
>>>> +            continue;
>>>> +
>>>> +        acpi_bus_get_device(handle, &d);
>>>> +        if (!strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID))
>>>> +            break;
>>>> +
>>>> +        max_leaf_depth++;
>>>> +        handle = pr_ahandle;
>>>> +    }
>>>> +
>>> In the above loop, we break when we find a device with HID ==
>>> ACPI_PROCESSOR_CONTAINER_HID. Shouldn't we continue to parse as long as the
>>> parent HID == ACPI_PROCESSOR_CONTAINER_HID? This is required to make sure we
>>> parse states in levels higher than cluster level in processor hierarchy.
>>>
>>
>> Yes, thanks for pointing that out. With just clusters in _LPI on my dev
>> board, I missed it.
>>
> Same reason, I failed to notice it all this time :)

No worries.

>>> Also, I think it might be safe to break out of the loop if we didn't find
>>> _LPI package, instead of continuing. Given  the presence of LPI entry:
>>> "Enabled Parent State", I can't think of a non-ambiguous scenario where we
>>> might find LPI packages in state N and N+2, but not in N+1, as we will not
>>> be able to figure out which state in N enables which states in N+2.
>>> Thoughts?
>>
>> Though I admit I haven't thought in detail on how to deal with the
>> asymmetric topology, but that was the reason why I continue instead of
>> breaking.
>>
>> Excerpts from the spec: "... This example is symmetric but that is not a
>> requirement. For example, a system may contain a different number of
>> processors in different containers or an asymmetric hierarchy where one
>> side of the topology tree is deeper than another...."
>>
> If it addresses asymmetric topology, sure we can keep as it doesn't impact other
> scenarios. Also, we need to set handle=pr_ahandle prior to the continue statement.
>

Yes I noticed it yesterday, the more I think, I feel we can break out of
the loop. At any level, we need to have container nodes and that must
contain _LPI irrespective of asymmetricity. So you were right. I have
fixed accordingly and have pushed out on my branch.
Sudeep Holla June 10, 2016, 5:38 p.m. UTC | #5
Hi Rafael,

On 11/05/16 16:37, Sudeep Holla wrote:
> ACPI 6.0 introduced an optional object _LPI that provides an alternate
> method to describe Low Power Idle states. It defines the local power
> states for each node in a hierarchical processor topology. The OSPM can
> use _LPI object to select a local power state for each level of processor
> hierarchy in the system. They used to produce a composite power state
> request that is presented to the platform by the OSPM.
>
> Since multiple processors affect the idle state for any non-leaf hierarchy
> node, coordination of idle state requests between the processors is
> required. ACPI supports two different coordination schemes: Platform
> coordinated and  OS initiated.
>
> This patch adds initial support for Platform coordination scheme of LPI.
>

I have added support for autopromote states(basically skip flattening or
creating composite state). I have also fixed the bug discussed in this
thread with Prashant. Do you have any other feedback on this version
that I incorporate before posting next version.
Rafael J. Wysocki June 13, 2016, 9:05 p.m. UTC | #6
On Friday, June 10, 2016 06:38:01 PM Sudeep Holla wrote:
> Hi Rafael,

Hi,
 
> On 11/05/16 16:37, Sudeep Holla wrote:
> > ACPI 6.0 introduced an optional object _LPI that provides an alternate
> > method to describe Low Power Idle states. It defines the local power
> > states for each node in a hierarchical processor topology. The OSPM can
> > use _LPI object to select a local power state for each level of processor
> > hierarchy in the system. They used to produce a composite power state
> > request that is presented to the platform by the OSPM.
> >
> > Since multiple processors affect the idle state for any non-leaf hierarchy
> > node, coordination of idle state requests between the processors is
> > required. ACPI supports two different coordination schemes: Platform
> > coordinated and  OS initiated.
> >
> > This patch adds initial support for Platform coordination scheme of LPI.
> >
> 
> I have added support for autopromote states(basically skip flattening or
> creating composite state). I have also fixed the bug discussed in this
> thread with Prashant. Do you have any other feedback on this version
> that I incorporate before posting next version.

I'd really preferred it if you posted the next version without waiting for
my feedback to the previous one (as the feedback may not be relevant any
more among other things).

Thanks,
Rafael

--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Sudeep Holla June 14, 2016, 2:24 p.m. UTC | #7
On 13/06/16 22:05, Rafael J. Wysocki wrote:
> On Friday, June 10, 2016 06:38:01 PM Sudeep Holla wrote:
>> Hi Rafael,
>
> Hi,
>
>> On 11/05/16 16:37, Sudeep Holla wrote:
>>> ACPI 6.0 introduced an optional object _LPI that provides an alternate
>>> method to describe Low Power Idle states. It defines the local power
>>> states for each node in a hierarchical processor topology. The OSPM can
>>> use _LPI object to select a local power state for each level of processor
>>> hierarchy in the system. They used to produce a composite power state
>>> request that is presented to the platform by the OSPM.
>>>
>>> Since multiple processors affect the idle state for any non-leaf hierarchy
>>> node, coordination of idle state requests between the processors is
>>> required. ACPI supports two different coordination schemes: Platform
>>> coordinated and  OS initiated.
>>>
>>> This patch adds initial support for Platform coordination scheme of LPI.
>>>
>>
>> I have added support for autopromote states(basically skip flattening or
>> creating composite state). I have also fixed the bug discussed in this
>> thread with Prashant. Do you have any other feedback on this version
>> that I incorporate before posting next version.
>
> I'd really preferred it if you posted the next version without waiting for
> my feedback to the previous one (as the feedback may not be relevant any
> more among other things).
>

Sure, will do that soon.
diff mbox

Patch

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 31e8da648fff..71edf7b07409 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -302,6 +302,14 @@  acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context)
 EXPORT_SYMBOL(acpi_run_osc);
 
 bool osc_sb_apei_support_acked;
+
+/*
+ * ACPI 6.0 Section 8.4.4.2 Idle State Coordination
+ * OSPM supports platform coordinated low power idle(LPI) states
+ */
+bool osc_pc_lpi_support_confirmed;
+EXPORT_SYMBOL_GPL(osc_pc_lpi_support_confirmed);
+
 static u8 sb_uuid_str[] = "0811B06E-4A27-44F9-8D60-3CBBC22E7B48";
 static void acpi_bus_osc_support(void)
 {
@@ -322,6 +330,7 @@  static void acpi_bus_osc_support(void)
 		capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_PPC_OST_SUPPORT;
 
 	capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_HOTPLUG_OST_SUPPORT;
+	capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_PCLPI_SUPPORT;
 
 	if (!ghes_disable)
 		capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_APEI_SUPPORT;
@@ -329,9 +338,12 @@  static void acpi_bus_osc_support(void)
 		return;
 	if (ACPI_SUCCESS(acpi_run_osc(handle, &context))) {
 		u32 *capbuf_ret = context.ret.pointer;
-		if (context.ret.length > OSC_SUPPORT_DWORD)
+		if (context.ret.length > OSC_SUPPORT_DWORD) {
 			osc_sb_apei_support_acked =
 				capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT;
+			osc_pc_lpi_support_confirmed =
+				capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_PCLPI_SUPPORT;
+		}
 		kfree(context.ret.pointer);
 	}
 	/* do we need to check other returned cap? Sounds no */
diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index d2fa8cb82d2b..0ca14ac7bb28 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -90,7 +90,7 @@  static void acpi_processor_notify(acpi_handle handle, u32 event, void *data)
 						  pr->performance_platform_limit);
 		break;
 	case ACPI_PROCESSOR_NOTIFY_POWER:
-		acpi_processor_cst_has_changed(pr);
+		acpi_processor_power_state_has_changed(pr);
 		acpi_bus_generate_netlink_event(device->pnp.device_class,
 						  dev_name(&device->dev), event, 0);
 		break;
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index ca0de35d1c3a..549404a45b45 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -303,7 +303,6 @@  static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object *cst;
 
-
 	if (nocst)
 		return -ENODEV;
 
@@ -576,7 +575,7 @@  static int acpi_processor_power_verify(struct acpi_processor *pr)
 	return (working);
 }
 
-static int acpi_processor_get_power_info(struct acpi_processor *pr)
+static int acpi_processor_get_cstate_info(struct acpi_processor *pr)
 {
 	unsigned int i;
 	int result;
@@ -810,31 +809,12 @@  static void acpi_idle_enter_freeze(struct cpuidle_device *dev,
 	acpi_idle_do_entry(cx);
 }
 
-/**
- * acpi_processor_setup_cpuidle_cx - prepares and configures CPUIDLE
- * device i.e. per-cpu data
- *
- * @pr: the ACPI processor
- * @dev : the cpuidle device
- */
 static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
 					   struct cpuidle_device *dev)
 {
 	int i, count = CPUIDLE_DRIVER_STATE_START;
 	struct acpi_processor_cx *cx;
 
-	if (!pr->flags.power_setup_done)
-		return -EINVAL;
-
-	if (pr->flags.power == 0) {
-		return -EINVAL;
-	}
-
-	if (!dev)
-		return -EINVAL;
-
-	dev->cpu = pr->id;
-
 	if (max_cstate == 0)
 		max_cstate = 1;
 
@@ -857,31 +837,13 @@  static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
 	return 0;
 }
 
-/**
- * acpi_processor_setup_cpuidle states- prepares and configures cpuidle
- * global state data i.e. idle routines
- *
- * @pr: the ACPI processor
- */
-static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
+static int acpi_processor_setup_cstates(struct acpi_processor *pr)
 {
 	int i, count = CPUIDLE_DRIVER_STATE_START;
 	struct acpi_processor_cx *cx;
 	struct cpuidle_state *state;
 	struct cpuidle_driver *drv = &acpi_idle_driver;
 
-	if (!pr->flags.power_setup_done)
-		return -EINVAL;
-
-	if (pr->flags.power == 0)
-		return -EINVAL;
-
-	drv->safe_state_index = -1;
-	for (i = CPUIDLE_DRIVER_STATE_START; i < CPUIDLE_STATE_MAX; i++) {
-		drv->states[i].name[0] = '\0';
-		drv->states[i].desc[0] = '\0';
-	}
-
 	if (max_cstate == 0)
 		max_cstate = 1;
 
@@ -893,7 +855,7 @@  static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
 
 		state = &drv->states[count];
 		snprintf(state->name, CPUIDLE_NAME_LEN, "C%d", i);
-		strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
+		strlcpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
 		state->exit_latency = cx->latency;
 		state->target_residency = cx->latency * latency_factor;
 		state->enter = acpi_idle_enter;
@@ -952,7 +914,7 @@  static inline void acpi_processor_cstate_first_run_checks(void)
 
 static inline int disabled_by_idle_boot_param(void) { return 0; }
 static inline void acpi_processor_cstate_first_run_checks(void) { }
-static int acpi_processor_get_power_info(struct acpi_processor *pr)
+static int acpi_processor_get_cstate_info(struct acpi_processor *pr)
 {
 	return -ENODEV;
 }
@@ -963,13 +925,410 @@  static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
 	return -EINVAL;
 }
 
-static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
+static int acpi_processor_setup_cstates(struct acpi_processor *pr)
 {
 	return -EINVAL;
 }
 
 #endif /* CONFIG_ACPI_PROCESSOR_CSTATE */
 
+struct acpi_lpi_states_array {
+	unsigned int size;
+	struct acpi_lpi_state *entries;
+};
+
+static int obj_get_integer(union acpi_object *obj, u32 *value)
+{
+	if (obj->type != ACPI_TYPE_INTEGER)
+		return -EINVAL;
+
+	*value = obj->integer.value;
+	return 0;
+}
+
+static int acpi_processor_evaluate_lpi(acpi_handle handle,
+				       struct acpi_lpi_states_array *info)
+{
+	acpi_status status;
+	int ret = 0;
+	int pkg_count, state_idx = 1, loop;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *lpi_data;
+	struct acpi_lpi_state *lpi_state;
+
+	status = acpi_evaluate_object(handle, "_LPI", NULL, &buffer);
+	if (ACPI_FAILURE(status)) {
+		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No _LPI, giving up\n"));
+		return -ENODEV;
+	}
+
+	lpi_data = buffer.pointer;
+
+	/* There must be at least 4 elements = 3 elements + 1 package */
+	if (!lpi_data || lpi_data->type != ACPI_TYPE_PACKAGE ||
+	    lpi_data->package.count < 4) {
+		pr_debug("not enough elements in _LPI\n");
+		ret = -ENODATA;
+		goto end;
+	}
+
+	pkg_count = lpi_data->package.elements[2].integer.value;
+
+	/* Validate number of power states. */
+	if (pkg_count < 1 || pkg_count != lpi_data->package.count - 3) {
+		pr_debug("count given by _LPI is not valid\n");
+		ret = -ENODATA;
+		goto end;
+	}
+
+	lpi_state = kcalloc(pkg_count, sizeof(*lpi_state), GFP_KERNEL);
+	if (!lpi_state) {
+		ret = -ENOMEM;
+		goto end;
+	}
+
+	info->size = pkg_count;
+	info->entries = lpi_state;
+
+	/* LPI States start at index 3 */
+	for (loop = 3; state_idx <= pkg_count;
+	     loop++, state_idx++, lpi_state++) {
+		union acpi_object *element, *pkg_elem, *obj;
+
+		element = &lpi_data->package.elements[loop];
+		if (element->type != ACPI_TYPE_PACKAGE)
+			continue;
+
+		if (element->package.count < 7)
+			continue;
+
+		pkg_elem = element->package.elements;
+
+		obj = pkg_elem + 6;
+		if (obj->type == ACPI_TYPE_BUFFER) {
+			struct acpi_power_register *reg;
+
+			reg = (struct acpi_power_register *)obj->buffer.pointer;
+			if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
+			    (reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE))
+				continue;
+
+			lpi_state->address = reg->address;
+
+			if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
+				lpi_state->entry_method = ACPI_CSTATE_FFH;
+			else
+				lpi_state->entry_method = ACPI_CSTATE_SYSTEMIO;
+		} else if (obj->type == ACPI_TYPE_INTEGER) {
+			lpi_state->entry_method = ACPI_CSTATE_INTEGER;
+			lpi_state->address = obj->integer.value;
+		} else {
+			continue;
+		}
+
+		/* elements[7,8] skipped for now i.e. Residency/Usage counter*/
+
+		obj = pkg_elem + 9;
+		if (obj->type == ACPI_TYPE_STRING)
+			strlcpy(lpi_state->desc, obj->string.pointer,
+				ACPI_CX_DESC_LEN);
+
+		lpi_state->index = state_idx;
+		if (obj_get_integer(pkg_elem + 0, &lpi_state->min_residency)) {
+			pr_debug("No min. residency found, assuming 10 us\n");
+			lpi_state->min_residency = 10;
+		}
+
+		if (obj_get_integer(pkg_elem + 1, &lpi_state->wake_latency)) {
+			pr_debug("No wakeup residency found, assuming 10 us\n");
+			lpi_state->wake_latency = 10;
+		}
+
+		if (obj_get_integer(pkg_elem + 2, &lpi_state->flags))
+			lpi_state->flags = 0;
+
+		if (obj_get_integer(pkg_elem + 3, &lpi_state->arch_flags))
+			lpi_state->arch_flags = 0;
+
+		if (obj_get_integer(pkg_elem + 4, &lpi_state->res_cnt_freq))
+			lpi_state->res_cnt_freq = 1;
+
+		if (obj_get_integer(pkg_elem + 5, &lpi_state->enable_parent_state))
+			lpi_state->enable_parent_state = 0;
+	}
+
+	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d power states\n",
+			  state_idx));
+end:
+	kfree(buffer.pointer);
+	return ret;
+}
+
+/*
+ * max_leaf_depth - holds the depth of the processor hierarchy/tree
+ * flat_state_cnt - the number of composite LPI states after the process of flattening
+ */
+static int max_leaf_depth, flat_state_cnt;
+
+/**
+ * combine_lpi_states - combine local and parent LPI states to form a composite LPI state
+ *
+ * @local: local LPI state
+ * @parent: parent LPI state
+ * @result: composite LPI state
+ */
+static void combine_lpi_states(struct acpi_lpi_state *local,
+			       struct acpi_lpi_state *parent,
+			       struct acpi_lpi_state *result)
+{
+	result->min_residency = max(local->min_residency, parent->min_residency);
+	result->wake_latency = local->wake_latency + parent->wake_latency;
+	result->enable_parent_state = parent->enable_parent_state;
+	result->entry_method = local->entry_method;
+
+	if (parent->entry_method == ACPI_CSTATE_INTEGER)
+		result->address = local->address + parent->address;
+	else
+		result->address = parent->address;
+
+	result->index = parent->index;
+	result->flags = parent->flags;
+	result->arch_flags = parent->arch_flags;
+
+	strlcpy(result->desc, local->desc, ACPI_CX_DESC_LEN);
+	strlcat(result->desc, "+", ACPI_CX_DESC_LEN);
+	strlcat(result->desc, parent->desc, ACPI_CX_DESC_LEN);
+}
+
+#define ACPI_LPI_STATE_FLAGS_ENABLED			BIT(0)
+
+static int flatten_lpi_states(struct acpi_processor *pr,
+			      struct acpi_lpi_states_array *info,
+			      struct acpi_lpi_state *lpi,
+			      uint32_t depth)
+{
+	int j, state_count = info[depth].size;
+	struct acpi_lpi_state *t = info[depth].entries;
+
+	for (j = 0; j < state_count; j++, t++) {
+		struct acpi_lpi_state *flpi;
+		bool valid = false;
+
+		if (!(t->flags & ACPI_LPI_STATE_FLAGS_ENABLED))
+			continue;
+
+		flpi = &pr->power.lpi_states[flat_state_cnt];
+
+		if (depth == max_leaf_depth) { /* leaf/processor node */
+			memcpy(flpi, t, sizeof(*t));
+			flat_state_cnt++;
+			valid = true;
+		} else if (lpi && t->index <= lpi->enable_parent_state) {
+			combine_lpi_states(lpi, t, flpi);
+			flat_state_cnt++;
+			valid = true;
+		}
+
+		/*
+		 * flatten recursively from leaf until the highest level
+		 * (e.g. system) is reached
+		 */
+		if (valid && depth)
+			flatten_lpi_states(pr, info, flpi, depth - 1);
+	}
+	return 0;
+}
+
+static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
+{
+	int ret, i;
+	struct acpi_lpi_states_array *info;
+	struct acpi_device *d = NULL;
+	acpi_handle handle = pr->handle, pr_ahandle;
+	acpi_status status;
+
+	if (!osc_pc_lpi_support_confirmed)
+		return -EOPNOTSUPP;
+
+	max_leaf_depth = 0;
+	if (!acpi_has_method(handle, "_LPI"))
+		return -EINVAL;
+	flat_state_cnt = 0;
+
+	while (ACPI_SUCCESS(status = acpi_get_parent(handle, &pr_ahandle))) {
+		if (!acpi_has_method(handle, "_LPI"))
+			continue;
+
+		acpi_bus_get_device(handle, &d);
+		if (!strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID))
+			break;
+
+		max_leaf_depth++;
+		handle = pr_ahandle;
+	}
+
+	info = kcalloc(max_leaf_depth + 1, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	pr_ahandle = pr->handle;
+	for (i = max_leaf_depth; i >= 0 && ACPI_SUCCESS(status); i--) {
+		handle = pr_ahandle;
+		ret = acpi_processor_evaluate_lpi(handle, info + i);
+		if (ret)
+			break;
+
+		status = acpi_get_parent(handle, &pr_ahandle);
+	}
+
+	/* flatten all the LPI states in the entire hierarchy */
+	flatten_lpi_states(pr, info, NULL, max_leaf_depth);
+
+	pr->power.count = flat_state_cnt;
+
+	for (i = 0; i <= max_leaf_depth; i++)
+		kfree(info[i].entries);
+
+	kfree(info);
+
+	/* Tell driver that _LPI is supported. */
+	pr->flags.has_lpi = 1;
+	pr->flags.power = 1;
+
+	return 0;
+}
+
+int __weak acpi_processor_ffh_lpi_probe(unsigned int cpu)
+{
+	return -ENODEV;
+}
+
+int __weak acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi, int idx)
+{
+	return -ENODEV;
+}
+
+/**
+ * acpi_idle_lpi_enter - enters an ACPI any LPI state
+ * @dev: the target CPU
+ * @drv: cpuidle driver containing cpuidle state info
+ * @index: index of target state
+ *
+ * Return: 0 for success or negative value for error
+ */
+static int acpi_idle_lpi_enter(struct cpuidle_device *dev,
+			       struct cpuidle_driver *drv, int index)
+{
+	struct acpi_processor *pr;
+	struct acpi_lpi_state *lpi;
+
+	pr = __this_cpu_read(processors);
+
+	if (unlikely(!pr))
+		return -EINVAL;
+
+	lpi = &pr->power.lpi_states[index];
+	if (lpi->entry_method == ACPI_CSTATE_FFH)
+		return acpi_processor_ffh_lpi_enter(lpi, index);
+
+	return -EINVAL;
+}
+
+static int acpi_processor_setup_lpi_states(struct acpi_processor *pr)
+{
+	int i;
+	struct acpi_lpi_state *lpi;
+	struct cpuidle_state *state;
+	struct cpuidle_driver *drv = &acpi_idle_driver;
+
+	if (!pr->flags.has_lpi)
+		return -EOPNOTSUPP;
+
+	for (i = 0; i < flat_state_cnt && i < CPUIDLE_STATE_MAX; i++) {
+		lpi = &pr->power.lpi_states[i];
+
+		state = &drv->states[i];
+		snprintf(state->name, CPUIDLE_NAME_LEN, "LPI-%d", i);
+		strlcpy(state->desc, lpi->desc, CPUIDLE_DESC_LEN);
+		state->exit_latency = lpi->wake_latency;
+		state->target_residency = lpi->min_residency;
+		if (lpi->arch_flags)
+			state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+		state->enter = acpi_idle_lpi_enter;
+		drv->safe_state_index = i;
+	}
+
+	drv->state_count = i;
+
+	return 0;
+}
+
+/**
+ * acpi_processor_setup_cpuidle_states- prepares and configures cpuidle
+ * global state data i.e. idle routines
+ *
+ * @pr: the ACPI processor
+ */
+static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
+{
+	int i;
+	struct cpuidle_driver *drv = &acpi_idle_driver;
+
+	if (!pr->flags.power_setup_done)
+		return -EINVAL;
+
+	if (pr->flags.power == 0)
+		return -EINVAL;
+
+	drv->safe_state_index = -1;
+	for (i = CPUIDLE_DRIVER_STATE_START; i < CPUIDLE_STATE_MAX; i++) {
+		drv->states[i].name[0] = '\0';
+		drv->states[i].desc[0] = '\0';
+	}
+
+	if (pr->flags.has_lpi)
+		return acpi_processor_setup_lpi_states(pr);
+
+	return acpi_processor_setup_cstates(pr);
+}
+
+/**
+ * acpi_processor_setup_cpuidle_dev - prepares and configures CPUIDLE
+ * device i.e. per-cpu data
+ *
+ * @pr: the ACPI processor
+ * @dev : the cpuidle device
+ */
+static int acpi_processor_setup_cpuidle_dev(struct acpi_processor *pr,
+					    struct cpuidle_device *dev)
+{
+	if (!pr->flags.power_setup_done)
+		return -EINVAL;
+
+	if (pr->flags.power == 0)
+		return -EINVAL;
+
+	if (!dev)
+		return -EINVAL;
+
+	dev->cpu = pr->id;
+	if (pr->flags.has_lpi)
+		return acpi_processor_ffh_lpi_probe(pr->id);
+
+	return acpi_processor_setup_cpuidle_cx(pr, dev);
+}
+
+static int acpi_processor_get_power_info(struct acpi_processor *pr)
+{
+	int ret;
+
+	ret = acpi_processor_get_lpi_info(pr);
+	if (ret)
+		ret = acpi_processor_get_cstate_info(pr);
+
+	return ret;
+}
+
 int acpi_processor_hotplug(struct acpi_processor *pr)
 {
 	int ret = 0;
@@ -978,18 +1337,15 @@  int acpi_processor_hotplug(struct acpi_processor *pr)
 	if (disabled_by_idle_boot_param())
 		return 0;
 
-	if (nocst)
-		return -ENODEV;
-
 	if (!pr->flags.power_setup_done)
 		return -ENODEV;
 
 	dev = per_cpu(acpi_cpuidle_device, pr->id);
 	cpuidle_pause_and_lock();
 	cpuidle_disable_device(dev);
-	acpi_processor_get_power_info(pr);
-	if (pr->flags.power) {
-		acpi_processor_setup_cpuidle_cx(pr, dev);
+	ret = acpi_processor_get_power_info(pr);
+	if (!ret && pr->flags.power) {
+		acpi_processor_setup_cpuidle_dev(pr, dev);
 		ret = cpuidle_enable_device(dev);
 	}
 	cpuidle_resume_and_unlock();
@@ -997,7 +1353,7 @@  int acpi_processor_hotplug(struct acpi_processor *pr)
 	return ret;
 }
 
-int acpi_processor_cst_has_changed(struct acpi_processor *pr)
+int acpi_processor_power_state_has_changed(struct acpi_processor *pr)
 {
 	int cpu;
 	struct acpi_processor *_pr;
@@ -1006,9 +1362,6 @@  int acpi_processor_cst_has_changed(struct acpi_processor *pr)
 	if (disabled_by_idle_boot_param())
 		return 0;
 
-	if (nocst)
-		return -ENODEV;
-
 	if (!pr->flags.power_setup_done)
 		return -ENODEV;
 
@@ -1045,7 +1398,7 @@  int acpi_processor_cst_has_changed(struct acpi_processor *pr)
 			acpi_processor_get_power_info(_pr);
 			if (_pr->flags.power) {
 				dev = per_cpu(acpi_cpuidle_device, cpu);
-				acpi_processor_setup_cpuidle_cx(_pr, dev);
+				acpi_processor_setup_cpuidle_dev(_pr, dev);
 				cpuidle_enable_device(dev);
 			}
 		}
@@ -1092,7 +1445,7 @@  int acpi_processor_power_init(struct acpi_processor *pr)
 			return -ENOMEM;
 		per_cpu(acpi_cpuidle_device, pr->id) = dev;
 
-		acpi_processor_setup_cpuidle_cx(pr, dev);
+		acpi_processor_setup_cpuidle_dev(pr, dev);
 
 		/* Register per-cpu cpuidle_device. Cpuidle driver
 		 * must already be registered before registering device
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 48779d678122..e2dcb0c51554 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -39,6 +39,7 @@ 
 #define ACPI_CSTATE_SYSTEMIO	0
 #define ACPI_CSTATE_FFH		1
 #define ACPI_CSTATE_HALT	2
+#define ACPI_CSTATE_INTEGER	3
 
 #define ACPI_CX_DESC_LEN	32
 
@@ -67,9 +68,25 @@  struct acpi_processor_cx {
 	char desc[ACPI_CX_DESC_LEN];
 };
 
+struct acpi_lpi_state {
+	u32 min_residency;
+	u32 wake_latency; /* worst case */
+	u32 flags;
+	u32 arch_flags;
+	u32 res_cnt_freq;
+	u32 enable_parent_state;
+	u64 address;
+	u8 index;
+	u8 entry_method;
+	char desc[ACPI_CX_DESC_LEN];
+};
+
 struct acpi_processor_power {
 	int count;
-	struct acpi_processor_cx states[ACPI_PROCESSOR_MAX_POWER];
+	union {
+		struct acpi_processor_cx states[ACPI_PROCESSOR_MAX_POWER];
+		struct acpi_lpi_state lpi_states[ACPI_PROCESSOR_MAX_POWER];
+	};
 	int timer_broadcast_on_state;
 };
 
@@ -189,6 +206,7 @@  struct acpi_processor_flags {
 	u8 bm_control:1;
 	u8 bm_check:1;
 	u8 has_cst:1;
+	u8 has_lpi:1;
 	u8 power_setup_done:1;
 	u8 bm_rld_set:1;
 	u8 need_hotplug_init:1;
@@ -371,7 +389,7 @@  extern struct cpuidle_driver acpi_idle_driver;
 #ifdef CONFIG_ACPI_PROCESSOR_IDLE
 int acpi_processor_power_init(struct acpi_processor *pr);
 int acpi_processor_power_exit(struct acpi_processor *pr);
-int acpi_processor_cst_has_changed(struct acpi_processor *pr);
+int acpi_processor_power_state_has_changed(struct acpi_processor *pr);
 int acpi_processor_hotplug(struct acpi_processor *pr);
 #else
 static inline int acpi_processor_power_init(struct acpi_processor *pr)
@@ -384,7 +402,7 @@  static inline int acpi_processor_power_exit(struct acpi_processor *pr)
 	return -ENODEV;
 }
 
-static inline int acpi_processor_cst_has_changed(struct acpi_processor *pr)
+static inline int acpi_processor_power_state_has_changed(struct acpi_processor *pr)
 {
 	return -ENODEV;
 }
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 288fac5294f5..65754566ae17 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -444,8 +444,12 @@  acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context);
 #define OSC_SB_HOTPLUG_OST_SUPPORT		0x00000008
 #define OSC_SB_APEI_SUPPORT			0x00000010
 #define OSC_SB_CPC_SUPPORT			0x00000020
+#define OSC_SB_CPCV2_SUPPORT			0x00000040
+#define OSC_SB_PCLPI_SUPPORT			0x00000080
+#define OSC_SB_OSLPI_SUPPORT			0x00000100
 
 extern bool osc_sb_apei_support_acked;
+extern bool osc_pc_lpi_support_confirmed;
 
 /* PCI Host Bridge _OSC: Capabilities DWORD 2: Support Field */
 #define OSC_PCI_EXT_CONFIG_SUPPORT		0x00000001