ACPI: processor: Export acpi_processor_evaluate_cst()
The intel_idle driver will be modified to use ACPI _CST subsequently
and it will need to call acpi_processor_evaluate_cst(), so move that
function to acpi_processor.c so that it is always present (which is
required by intel_idle) and export it to modules to allow the ACPI
processor driver (which is modular) to call it.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index 8a53f3c5..5379bc3 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -729,4 +729,161 @@ bool acpi_processor_claim_cst_control(void)
return true;
}
EXPORT_SYMBOL_GPL(acpi_processor_claim_cst_control);
+
+/**
+ * acpi_processor_evaluate_cst - Evaluate the processor _CST control method.
+ * @handle: ACPI handle of the processor object containing the _CST.
+ * @cpu: The numeric ID of the target CPU.
+ * @info: Object write the C-states information into.
+ *
+ * Extract the C-state information for the given CPU from the output of the _CST
+ * control method under the corresponding ACPI processor object (or processor
+ * device object) and populate @info with it.
+ *
+ * If any ACPI_ADR_SPACE_FIXED_HARDWARE C-states are found, invoke
+ * acpi_processor_ffh_cstate_probe() to verify them and update the
+ * cpu_cstate_entry data for @cpu.
+ */
+int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
+ struct acpi_processor_power *info)
+{
+ struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+ union acpi_object *cst;
+ acpi_status status;
+ u64 count;
+ int last_index = 0;
+ int i, ret = 0;
+
+ status = acpi_evaluate_object(handle, "_CST", NULL, &buffer);
+ if (ACPI_FAILURE(status)) {
+ acpi_handle_debug(handle, "No _CST\n");
+ return -ENODEV;
+ }
+
+ cst = buffer.pointer;
+
+ /* There must be at least 2 elements. */
+ if (!cst || cst->type != ACPI_TYPE_PACKAGE || cst->package.count < 2) {
+ acpi_handle_warn(handle, "Invalid _CST output\n");
+ ret = -EFAULT;
+ goto end;
+ }
+
+ count = cst->package.elements[0].integer.value;
+
+ /* Validate the number of C-states. */
+ if (count < 1 || count != cst->package.count - 1) {
+ acpi_handle_warn(handle, "Inconsistent _CST data\n");
+ ret = -EFAULT;
+ goto end;
+ }
+
+ for (i = 1; i <= count; i++) {
+ union acpi_object *element;
+ union acpi_object *obj;
+ struct acpi_power_register *reg;
+ struct acpi_processor_cx cx;
+
+ /*
+ * If there is not enough space for all C-states, skip the
+ * excess ones and log a warning.
+ */
+ if (last_index >= ACPI_PROCESSOR_MAX_POWER - 1) {
+ acpi_handle_warn(handle,
+ "No room for more idle states (limit: %d)\n",
+ ACPI_PROCESSOR_MAX_POWER - 1);
+ break;
+ }
+
+ memset(&cx, 0, sizeof(cx));
+
+ element = &cst->package.elements[i];
+ if (element->type != ACPI_TYPE_PACKAGE)
+ continue;
+
+ if (element->package.count != 4)
+ continue;
+
+ obj = &element->package.elements[0];
+
+ if (obj->type != ACPI_TYPE_BUFFER)
+ continue;
+
+ reg = (struct acpi_power_register *)obj->buffer.pointer;
+
+ obj = &element->package.elements[1];
+ if (obj->type != ACPI_TYPE_INTEGER)
+ continue;
+
+ cx.type = obj->integer.value;
+ /*
+ * There are known cases in which the _CST output does not
+ * contain C1, so if the type of the first state found is not
+ * C1, leave an empty slot for C1 to be filled in later.
+ */
+ if (i == 1 && cx.type != ACPI_STATE_C1)
+ last_index = 1;
+
+ cx.address = reg->address;
+ cx.index = last_index + 1;
+
+ if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
+ if (!acpi_processor_ffh_cstate_probe(cpu, &cx, reg)) {
+ /*
+ * In the majority of cases _CST describes C1 as
+ * a FIXED_HARDWARE C-state, but if the command
+ * line forbids using MWAIT, use CSTATE_HALT for
+ * C1 regardless.
+ */
+ if (cx.type == ACPI_STATE_C1 &&
+ boot_option_idle_override == IDLE_NOMWAIT) {
+ cx.entry_method = ACPI_CSTATE_HALT;
+ snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
+ } else {
+ cx.entry_method = ACPI_CSTATE_FFH;
+ }
+ } else if (cx.type == ACPI_STATE_C1) {
+ /*
+ * In the special case of C1, FIXED_HARDWARE can
+ * be handled by executing the HLT instruction.
+ */
+ cx.entry_method = ACPI_CSTATE_HALT;
+ snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
+ } else {
+ continue;
+ }
+ } else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
+ cx.entry_method = ACPI_CSTATE_SYSTEMIO;
+ snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI IOPORT 0x%x",
+ cx.address);
+ } else {
+ continue;
+ }
+
+ if (cx.type == ACPI_STATE_C1)
+ cx.valid = 1;
+
+ obj = &element->package.elements[2];
+ if (obj->type != ACPI_TYPE_INTEGER)
+ continue;
+
+ cx.latency = obj->integer.value;
+
+ obj = &element->package.elements[3];
+ if (obj->type != ACPI_TYPE_INTEGER)
+ continue;
+
+ memcpy(&info->states[++last_index], &cx, sizeof(cx));
+ }
+
+ acpi_handle_info(handle, "Found %d idle states\n", last_index);
+
+ info->count = last_index;
+
+ end:
+ kfree(buffer.pointer);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(acpi_processor_evaluate_cst);
#endif /* CONFIG_ACPI_PROCESSOR_CSTATE */
