[PATCH] ACPI: PM: s2idle: Add AMD support to handle _DSM during S2Idle

[Shyam Sundar S K <Shyam-sundar.S-k@amd.com>]

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.

This patch adds AMD support for S2Idle to parse the UUID, evaluate the
_DSM methods, preparing the Idle constaint 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>
---
 drivers/acpi/sleep.c | 166 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 158 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index aff13bf4d947..a36b4ddcd1e9 100644
--- a/drivers/acpi/sleep.c
+++ b/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 +738,128 @@ 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_info(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;
+			default:
+				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;
+					default:
+						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,
+							 "index:%d Name:%s\n", k, 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)
 {
@@ -883,7 +1008,7 @@ 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",
@@ -894,6 +1019,7 @@ static int lps0_device_attach(struct acpi_device *adev,
 			      const struct acpi_device_id *not_used)
 {
 	union acpi_object *out_obj;
+	struct cpuinfo_x86 *c = &boot_cpu_data;
 
 	if (lps0_device_handle)
 		return 0;
@@ -901,9 +1027,17 @@ static int lps0_device_attach(struct acpi_device *adev,
 	if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
 		return 0;
 
-	guid_parse(ACPI_LPS0_DSM_UUID, &lps0_dsm_guid);
+	if (c->x86_vendor == X86_VENDOR_AMD) {
+		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);
+		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. */
-	out_obj = acpi_evaluate_dsm(adev->handle, &lps0_dsm_guid, 1, 0, NULL);
 	if (!out_obj || out_obj->type != ACPI_TYPE_BUFFER) {
 		acpi_handle_debug(adev->handle,
 				  "_DSM function 0 evaluation failed\n");
@@ -919,7 +1053,12 @@ static int lps0_device_attach(struct acpi_device *adev,
 
 	lps0_device_handle = adev->handle;
 
-	lpi_device_get_constraints();
+	if (c->x86_vendor == X86_VENDOR_AMD) {
+		acpi_handle_info(adev->handle, "lpi_device_get_constraints_amd\n");
+		lpi_device_get_constraints_amd();
+	} else {
+		lpi_device_get_constraints();
+	}
 
 	/*
 	 * Use suspend-to-idle by default if the default suspend mode was not
@@ -968,14 +1107,19 @@ static int acpi_s2idle_prepare(void)
 
 static int acpi_s2idle_prepare_late(void)
 {
+	struct cpuinfo_x86 *c = &boot_cpu_data;
 	if (!lps0_device_handle || sleep_no_lps0)
 		return 0;
 
 	if (pm_debug_messages_on)
 		lpi_check_constraints();
 
-	acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_OFF);
-	acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY);
+	if (c->x86_vendor == X86_VENDOR_AMD) {
+		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;
 }
@@ -1048,11 +1192,17 @@ static bool acpi_s2idle_wake(void)
 
 static void acpi_s2idle_restore_early(void)
 {
+	struct cpuinfo_x86 *c = &boot_cpu_data;
+
 	if (!lps0_device_handle || sleep_no_lps0)
 		return;
 
-	acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT);
-	acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON);
+	if (c->x86_vendor == X86_VENDOR_AMD) {
+		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)
-- 
2.25.1