Re-enable lpit

src/Kconfig

@@ -720,6 +720,12 @@ config ACPI_NHLT
 	help
 	  Build support for NHLT (non HD Audio) ACPI table generation.
 
+config ACPI_LPIT
+	bool
+	default y
+	help
+	  Build an ACPI Low Power Idle Table.
+
 #These Options are here to avoid "undefined" warnings.
 #The actual selection and help texts are in the following menu.
 

src/acpi/acpi.c

@@ -1264,6 +1264,78 @@ void acpi_create_fadt(acpi_fadt_t *fadt, acpi_facs_t *facs, void *dsdt)
 	    acpi_checksum((void *) fadt, header->length);
 }
 
+/*
+ * The value of residency couneter register address is MSR value and
+ * implementation specific.e.e.g, scenerios:
+ * 1. For CNL: space_id:0,residency_counter.addrl:0x632 and ACPI_LPIT
+ * selected in soc Kconfig sysfs file thet kernel creates is
+ * /sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us.
+ * 2. For CNL: space_id:0, residency_counter.addrl:0xfe000000 + 0x193C
+ * and ACPI_LPIT elected in soc Kconfig sysfs file thet kernel creates is
+ * /sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us
+ * which gets populated with integer values whenever system goes in s0ix.
+ */
+__weak void soc_residency_counter(struct acpi_lpit_native *lpit_soc)
+{
+	lpit_soc->header.unique_id = 0;
+
+	lpit_soc->residency = 0x7530;
+	lpit_soc->latency = 0xBB8;
+
+	lpit_soc->entry_trigger.space_id = 0x7f;
+	lpit_soc->entry_trigger.bit_width = 0x01;
+	lpit_soc->entry_trigger.bit_offset = 0x02;
+	lpit_soc->entry_trigger.addrl = 0x60;
+
+	lpit_soc->residency_counter.space_id = 0x7f;
+	lpit_soc->residency_counter.bit_width = 0x40;
+	lpit_soc->residency_counter.addrl = 0x632;
+}
+
+__weak void system_residency_counter(struct acpi_lpit_native *lpit_system)
+{
+	lpit_system->header.unique_id = 1;
+
+	lpit_system->counter_frequency = 0x256c;
+	lpit_system->residency = 0x7530;
+	lpit_system->latency = 0xBB8;
+
+	lpit_system->entry_trigger.space_id = 0x7f;
+	lpit_system->entry_trigger.bit_width = 0x01;
+	lpit_system->entry_trigger.bit_offset = 0x02;
+	lpit_system->entry_trigger.addrl = 0x60;
+
+	lpit_system->residency_counter.space_id = 0x00;
+	lpit_system->residency_counter.bit_width = 0x20;
+	lpit_system->residency_counter.access_size = 0x03;
+	lpit_system->residency_counter.addrl = 0xfe00193c;
+}
+
+static void acpi_create_lpit_generator(acpi_table_lpit *lpit)
+{
+	acpi_header_t *header = &(lpit->header);
+
+	memset((void *)lpit, 0, sizeof(acpi_table_lpit));
+
+	memcpy(header->signature, "LPIT", 4);
+	header->revision = 2; /* ACPI 1.0/2.0: ?, ACPI 3.0/4.0: 2 */
+	memcpy(header->oem_id, OEM_ID, 6);
+	memcpy(header->oem_table_id, ACPI_TABLE_CREATOR, 8);
+	header->oem_revision = 42;
+	memcpy(header->asl_compiler_id, ASLC, 4);
+	header->asl_compiler_revision = 0;
+	header->length = sizeof(acpi_table_lpit);
+	lpit->lpit_soc.header.length = sizeof(struct acpi_lpit_native);
+	lpit->lpit_system.header.length = sizeof(struct acpi_lpit_native);
+
+	soc_residency_counter(&lpit->lpit_soc);
+	system_residency_counter(&lpit->lpit_system);
+
+
+	/* (Re)calculate length and checksum. */
+	header->checksum = acpi_checksum((void *)lpit, header->length);
+}
+
 unsigned long __weak fw_cfg_acpi_tables(unsigned long start)
 {
 	return 0;
@@ -1284,6 +1356,7 @@ unsigned long write_acpi_tables(unsigned long start)
 	acpi_tcpa_t *tcpa;
 	acpi_tpm2_t *tpm2;
 	acpi_madt_t *madt;
+	acpi_table_lpit *lpit;
 	struct device *dev;
 	unsigned long fw;
 	size_t slic_size, dsdt_size;
@@ -1489,6 +1562,18 @@ unsigned long write_acpi_tables(unsigned long start)
 		current += madt->header.length;
 		acpi_add_table(rsdp, madt);
 	}
+
+	if (CONFIG(ACPI_LPIT)) {
+		printk(BIOS_DEBUG, "ACPI:     * LPIT\n");
+
+		lpit = (acpi_table_lpit *)current;
+		acpi_create_lpit_generator(lpit);
+		if (lpit->header.length >= sizeof(acpi_table_lpit)) {
+			current += lpit->header.length;
+			acpi_add_table(rsdp, lpit);
+		}
+	}
+
 	current = acpi_align_current(current);
 
 	printk(BIOS_DEBUG, "current = %lx\n", current);

src/include/acpi/acpi.h

@@ -257,6 +257,63 @@ typedef struct acpi_madt {
 	u32 flags;			/* Multiple APIC flags */
 } __packed acpi_madt_t;
 
+/*******************************************************************************
+ *
+ * LPIT - Low Power Idle Table
+ *
+ * Conforms to "ACPI Low Power Idle Table (LPIT)" July 2014.
+ *
+ ******************************************************************************/
+
+typedef struct acpi_lpi_state_flags {
+	u32 disabled:1;
+	u32 counterunavailable:1;
+	u32 reserved:30;
+} __packed acpi_lpi_state_flags;
+
+/* LPIT subtable header */
+
+typedef struct acpi_lpit_header {
+	u32 type;               /* Subtable type */
+	u32 length;             /* Subtable length */
+	u16 unique_id;
+	u16 reserved;
+	acpi_lpi_state_flags flags;
+} __packed acpi_lpit_header;
+
+/* Values for subtable Type above */
+
+enum acpi_lpit_type {
+	ACPI_LPIT_TYPE_NATIVE_CSTATE = 0x00,
+	ACPI_LPIT_TYPE_RESERVED = 0x01  /* 1 and above are reserved */
+};
+
+/* Masks for Flags field above  */
+
+#define ACPI_LPIT_STATE_DISABLED    (1)
+#define ACPI_LPIT_NO_COUNTER        (1<<1)
+
+/*
+ * LPIT subtables, correspond to Type in struct acpi_lpit_header
+ */
+
+/* 0x00: Native C-state instruction based LPI structure */
+
+struct acpi_lpit_native {
+	struct acpi_lpit_header header;
+	struct acpi_gen_regaddr entry_trigger;
+	u32 residency;
+	u32 latency;
+	struct acpi_gen_regaddr residency_counter;
+	u64 counter_frequency;
+};
+
+typedef struct acpi_table_lpit {
+	struct acpi_table_header header;        /* Common ACPI table header */
+	struct acpi_lpit_native lpit_soc;
+	struct acpi_lpit_native lpit_system;
+} __packed acpi_table_lpit;
+
 /* VFCT image header */
 typedef struct acpi_vfct_image_hdr {
 	u32 PCIBus;
@@ -897,6 +954,9 @@ struct acpi_spmi {
 
 unsigned long fw_cfg_acpi_tables(unsigned long start);
 
+void soc_residency_counter(struct acpi_lpit_native *lpit_soc);
+void system_residency_counter(struct acpi_lpit_native *lpit_system);
+
 /* These are implemented by the target port or north/southbridge. */
 unsigned long write_acpi_tables(unsigned long addr);
 unsigned long acpi_fill_madt(unsigned long current);