dptf: Add support for Critical Policies

This patch adds support for DPTF Critical Policies, which are consist
of Method definitions only. They are `_CRT` and `_HOT`, which are
defined as temperature thresholds that, when exceeded, will execute a
graceful suspend or a graceful shutdown, respectively.

BUG=b:143539650
TEST=compiles

Change-Id: I711ecdcf17ae8f6e653f33069201da4515ace85e
Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41887
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

src/acpi/acpigen_dptf.c

@@ -262,3 +262,21 @@ void dptf_write_passive_policies(const struct dptf_passive_policy *policies, int
 	write_thermal_relationship_table(policies, max_count);
 	write_all_PSV(policies, max_count);
 }
+
+void dptf_write_critical_policies(const struct dptf_critical_policy *policies, int max_count)
+{
+	int i;
+
+	for (i = 0; i < max_count; ++i) {
+		if (policies[i].source == DPTF_NONE)
+			break;
+
+		dptf_write_scope(policies[i].source);
+
+		/* Choose _CRT or _HOT */
+		write_simple_return_method(policies[i].type == DPTF_CRITICAL_SHUTDOWN ?
+					   "_CRT" : "_HOT", to_acpi_temp(policies[i].temp));
+
+		acpigen_pop_len(); /* Scope */
+	}
+}

src/drivers/intel/dptf/chip.h

@@ -8,6 +8,7 @@
 struct drivers_intel_dptf_config {
 	struct {
 		struct dptf_active_policy active[DPTF_MAX_ACTIVE_POLICIES];
+		struct dptf_critical_policy critical[DPTF_MAX_CRITICAL_POLICIES];
 		struct dptf_passive_policy passive[DPTF_MAX_PASSIVE_POLICIES];
 	} policies;
 };

src/drivers/intel/dptf/dptf.c

@@ -41,6 +41,11 @@ static bool is_participant_used(const struct drivers_intel_dptf_config *config,
 		    config->policies.passive[i].target == participant)
 			return true;
 
+	/* Critical? */
+	for (i = 0; i < DPTF_MAX_CRITICAL_POLICIES; ++i)
+		if (config->policies.critical[i].source == participant)
+			return true;
+
 	/* Check fan as well (its use is implicit in the Active policy) */
 	if (participant == DPTF_FAN && config->policies.active[0].target != DPTF_NONE)
 		return true;
@@ -64,6 +69,9 @@ static void dptf_fill_ssdt(const struct device *dev)
 	dptf_write_passive_policies(config->policies.passive,
 				    DPTF_MAX_PASSIVE_POLICIES);
 
+	dptf_write_critical_policies(config->policies.critical,
+				     DPTF_MAX_CRITICAL_POLICIES);
+
 	printk(BIOS_INFO, "\\_SB.DPTF: %s at %s\n", dev->chip_ops->name, dev_path(dev));
 }
 

src/include/acpi/acpigen_dptf.h

@@ -28,6 +28,7 @@ enum {
 	DPTF_MAX_ACX			= 10,
 	DPTF_MAX_ACTIVE_POLICIES	= (DPTF_PARTICIPANT_COUNT-1),
 	DPTF_MAX_PASSIVE_POLICIES	= (DPTF_PARTICIPANT_COUNT-1),
+	DPTF_MAX_CRITICAL_POLICIES	= (DPTF_PARTICIPANT_COUNT-1),
 };
 
 /* Active Policy */
@@ -59,6 +60,22 @@ struct dptf_passive_policy {
 	uint8_t priority;
 };
 
+/* Critical Policy type: graceful S4 transition or graceful shutdown */
+enum dptf_critical_policy_type {
+	DPTF_CRITICAL_S4,
+	DPTF_CRITICAL_SHUTDOWN,
+};
+
+/* Critical Policy */
+struct dptf_critical_policy {
+	/* The device that can trigger a critical event */
+	enum dptf_participant source;
+	/* What type of critical policy */
+	enum dptf_critical_policy_type type;
+	/* Temperature to activate policy, degrees C */
+	uint8_t temp;
+};
+
 /*
  * This function provides tables of temperature and corresponding fan or percent.  When the
  * temperature thresholds are met (_AC0 - _AC9), the fan is driven to corresponding percentage
@@ -74,6 +91,13 @@ void dptf_write_active_policies(const struct dptf_active_policy *policies, int m
  */
 void dptf_write_passive_policies(const struct dptf_passive_policy *policies, int max_count);
 
+/*
+ * Critical policies are temperature thresholds that, when reached, will cause the system to
+ * take some emergency action in order to eliminate excess temperatures from damaging the
+ * system. The emergency actions are a graceful suspend or a graceful shutdown.
+ */
+void dptf_write_critical_policies(const struct dptf_critical_policy *policies, int max_count);
+
 /* Helper method to open the scope for a given participant. */
 void dptf_write_scope(enum dptf_participant participant);