ACPI / processor_idle: Add support for Low Power Idle(LPI) states
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.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 262ca31..80ebb05 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -302,6 +302,14 @@
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 @@
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 @@
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 */