ACPI: PM: s2idle: Add AMD support to handle _DSM

Initial support for S2Idle based on the Intel implementation [1] does not
work for AMD as the BIOS implementation for ACPI methods like the _DSM
are not standardized.

So, the way in which the UUID's were parsed and the ACPI packages were
retrieved out of the ACPI objects are not the same between Intel and AMD.

Add AMD support for S2Idle to parse the UUID, evaluate the
_DSM methods, prepare the Idle constraint list etc.

Link: https://uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf # [1]
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sleep.c

@@ -710,6 +710,11 @@ static const struct acpi_device_id lps0_device_ids[] = {
 #define ACPI_LPS0_ENTRY		5
 #define ACPI_LPS0_EXIT		6
 
+/* AMD */
+#define ACPI_LPS0_DSM_UUID_AMD      "e3f32452-febc-43ce-9039-932122d37721"
+#define ACPI_LPS0_SCREEN_OFF_AMD    4
+#define ACPI_LPS0_SCREEN_ON_AMD     5
+
 static acpi_handle lps0_device_handle;
 static guid_t lps0_dsm_guid;
 static char lps0_dsm_func_mask;
@@ -733,8 +738,124 @@ struct lpi_constraints {
 	int min_dstate;
 };
 
+/* AMD */
+/* Device constraint entry structure */
+struct lpi_device_info_amd {
+	int revision;
+	int count;
+	union acpi_object *package;
+};
+
+/* Constraint package structure */
+struct lpi_device_constraint_amd {
+	char *name;
+	int enabled;
+	int function_states;
+	int min_dstate;
+};
+
 static struct lpi_constraints *lpi_constraints_table;
 static int lpi_constraints_table_size;
+static int rev_id;
+
+static void lpi_device_get_constraints_amd(void)
+{
+	union acpi_object *out_obj;
+	int i, j, k;
+
+	out_obj = acpi_evaluate_dsm_typed(lps0_device_handle, &lps0_dsm_guid,
+					  1, ACPI_LPS0_GET_DEVICE_CONSTRAINTS,
+					  NULL, ACPI_TYPE_PACKAGE);
+
+	if (!out_obj)
+		return;
+
+	acpi_handle_debug(lps0_device_handle, "_DSM function 1 eval %s\n",
+			  out_obj ? "successful" : "failed");
+
+	for (i = 0; i < out_obj->package.count; i++) {
+		union acpi_object *package = &out_obj->package.elements[i];
+		struct lpi_device_info_amd info = { };
+
+		if (package->type == ACPI_TYPE_INTEGER) {
+			switch (i) {
+			case 0:
+				info.revision = package->integer.value;
+				break;
+			case 1:
+				info.count = package->integer.value;
+				break;
+			}
+		} else if (package->type == ACPI_TYPE_PACKAGE) {
+			lpi_constraints_table = kcalloc(package->package.count,
+							sizeof(*lpi_constraints_table),
+							GFP_KERNEL);
+
+			if (!lpi_constraints_table)
+				goto free_acpi_buffer;
+
+			acpi_handle_info(lps0_device_handle,
+					 "LPI: constraints list begin:\n");
+
+			for (j = 0; j < package->package.count; ++j) {
+				union acpi_object *info_obj = &package->package.elements[j];
+				struct lpi_device_constraint_amd dev_info = {};
+				struct lpi_constraints *list;
+				acpi_status status;
+
+				for (k = 0; k < info_obj->package.count; ++k) {
+					union acpi_object *obj = &info_obj->package.elements[k];
+					union acpi_object *obj_new;
+
+					list = &lpi_constraints_table[lpi_constraints_table_size];
+					list->min_dstate = -1;
+
+					obj_new = &obj[k];
+					switch (k) {
+					case 0:
+						dev_info.enabled = obj->integer.value;
+						break;
+					case 1:
+						dev_info.name = obj->string.pointer;
+						break;
+					case 2:
+						dev_info.function_states = obj->integer.value;
+						break;
+					case 3:
+						dev_info.min_dstate = obj->integer.value;
+						break;
+					}
+
+					if (!dev_info.enabled || !dev_info.name ||
+					    !dev_info.min_dstate)
+						continue;
+
+					status = acpi_get_handle(NULL, dev_info.name,
+								 &list->handle);
+					if (ACPI_FAILURE(status))
+						continue;
+
+					acpi_handle_info(lps0_device_handle,
+							 "Name:%s\n", dev_info.name);
+
+					list->min_dstate = dev_info.min_dstate;
+
+					if (list->min_dstate < 0) {
+						acpi_handle_info(lps0_device_handle,
+								 "Incomplete constraint defined\n");
+						continue;
+					}
+				}
+				lpi_constraints_table_size++;
+			}
+		}
+	}
+
+	acpi_handle_info(lps0_device_handle, "LPI: constraints list end\n");
+
+free_acpi_buffer:
+	ACPI_FREE(out_obj);
+}
 
 static void lpi_device_get_constraints(void)
 {
@@ -883,13 +1004,22 @@ static void acpi_sleep_run_lps0_dsm(unsigned int func)
 	if (!(lps0_dsm_func_mask & (1 << func)))
 		return;
 
-	out_obj = acpi_evaluate_dsm(lps0_device_handle, &lps0_dsm_guid, 1, func, NULL);
+	out_obj = acpi_evaluate_dsm(lps0_device_handle, &lps0_dsm_guid, rev_id, func, NULL);
 	ACPI_FREE(out_obj);
 
 	acpi_handle_debug(lps0_device_handle, "_DSM function %u evaluation %s\n",
 			  func, out_obj ? "successful" : "failed");
 }
 
+static bool acpi_match_vendor_name(void)
+{
+#ifdef CONFIG_X86
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+		return true;
+#endif
+	return false;
+}
+
 static int lps0_device_attach(struct acpi_device *adev,
 			      const struct acpi_device_id *not_used)
 {
@@ -901,9 +1031,17 @@ static int lps0_device_attach(struct acpi_device *adev,
 	if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
 		return 0;
 
+	if (acpi_match_vendor_name()) {
+		guid_parse(ACPI_LPS0_DSM_UUID_AMD, &lps0_dsm_guid);
+		out_obj = acpi_evaluate_dsm(adev->handle, &lps0_dsm_guid, 0, 0, NULL);
+		rev_id = 0;
+	} else {
 		guid_parse(ACPI_LPS0_DSM_UUID, &lps0_dsm_guid);
-	/* Check if the _DSM is present and as expected. */
 		out_obj = acpi_evaluate_dsm(adev->handle, &lps0_dsm_guid, 1, 0, NULL);
+		rev_id = 1;
+	}
+
+	/* Check if the _DSM is present and as expected. */
 	if (!out_obj || out_obj->type != ACPI_TYPE_BUFFER) {
 		acpi_handle_debug(adev->handle,
 				  "_DSM function 0 evaluation failed\n");
@@ -919,6 +1057,9 @@ static int lps0_device_attach(struct acpi_device *adev,
 
 	lps0_device_handle = adev->handle;
 
+	if (acpi_match_vendor_name())
+		lpi_device_get_constraints_amd();
+	else
 		lpi_device_get_constraints();
 
 	/*
@@ -974,9 +1115,12 @@ static int acpi_s2idle_prepare_late(void)
 	if (pm_debug_messages_on)
 		lpi_check_constraints();
 
+	if (acpi_match_vendor_name()) {
+		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_OFF_AMD);
+	} else {
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_OFF);
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY);
-
+	}
 	return 0;
 }
 
@@ -1051,8 +1195,12 @@ static void acpi_s2idle_restore_early(void)
 	if (!lps0_device_handle || sleep_no_lps0)
 		return;
 
+	if (acpi_match_vendor_name()) {
+		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON_AMD);
+	} else {
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT);
 		acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON);
+	}
 }
 
 static void acpi_s2idle_restore(void)