amdsmu: Sleep entry/exit hints for PMFW

amdsmu_suspend() and amdsmu_resume() for sending hints to the AMD SMU
power management firmware (PMFW) that we are entering and exiting
s2idle. We also dump sleep metrics once we tell it we're exiting sleep,
so the relevant metrics are updated.

Register these as acpi_post_dev_suspend and acpi_post_dev_resume
eventhandlers.

Reviewed by:	olce
Approved by:	olce
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D48721

sys/dev/amdsmu/amdsmu.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: BSD-2-Clause
  *
- * Copyright (c) 2025 The FreeBSD Foundation
+ * Copyright (c) 2025-2026 The FreeBSD Foundation
  *
  * This software was developed by Aymeric Wibo <obiwac@freebsd.org>
  * under sponsorship from the FreeBSD Foundation.
@@ -14,6 +14,13 @@
 #include <sys/rman.h>
 #include <sys/sysctl.h>
 
+#include "opt_acpi.h"
+
+#if defined(DEV_ACPI)
+#include <contrib/dev/acpica/include/acpi.h>
+#include <dev/acpica/acpivar.h>
+#endif
+
 #include <dev/pci/pcivar.h>
 #include <dev/amdsmu/amdsmu.h>
 
@@ -289,6 +296,27 @@ amdsmu_fetch_idlemask(device_t dev)
 	sc->idlemask = amdsmu_read4(sc, SMU_REG_IDLEMASK);
 }
 
+static void
+amdsmu_suspend(device_t dev, enum power_stype stype)
+{
+	if (stype != POWER_STYPE_SUSPEND_TO_IDLE)
+		return;
+	if (amdsmu_cmd(dev, SMU_MSG_SLEEP_HINT, true, NULL) != 0)
+		device_printf(dev, "failed to hint to SMU to enter sleep");
+}
+
+static void
+amdsmu_resume(device_t dev, enum power_stype stype)
+{
+	if (stype != POWER_STYPE_SUSPEND_TO_IDLE)
+		return;
+	if (amdsmu_cmd(dev, SMU_MSG_SLEEP_HINT, false, NULL) != 0)
+		device_printf(dev, "failed to hint to SMU to exit sleep");
+	/* Update metrics after resume. */
+	amdsmu_dump_metrics(dev);
+	amdsmu_fetch_idlemask(dev);
+}
+
 static int
 amdsmu_attach(device_t dev)
 {
@@ -422,6 +450,19 @@ amdsmu_attach(device_t dev)
 	    "value is not documented - only used to help AMD internally debug "
 	    "issues");
 
+#if defined(DEV_ACPI)
+	/*
+	 * Register post device suspend/pre device resume eventhandlers.  We use
+	 * a lower priority for the suspend event as we want this to be called
+	 * after the SPMC suspend hook, and a higher priority for the resume
+	 * event as we want this to be called before the SPMC hook.
+	 */
+	sc->eh_suspend = EVENTHANDLER_REGISTER(acpi_post_dev_suspend,
+	    amdsmu_suspend, dev, -10);
+	sc->eh_resume = EVENTHANDLER_REGISTER(acpi_pre_dev_resume,
+	    amdsmu_resume, dev, 10);
+#endif
+
 	return (0);
 err_dump:
 	bus_space_unmap(sc->bus_tag, sc->reg_space, SMU_MEM_SIZE);
@@ -438,6 +479,11 @@ amdsmu_detach(device_t dev)
 	struct amdsmu_softc *sc = device_get_softc(dev);
 	int rid = 0;
 
+#if defined(DEV_ACPI)
+	EVENTHANDLER_DEREGISTER(acpi_post_dev_suspend, sc->eh_suspend);
+	EVENTHANDLER_DEREGISTER(acpi_pre_dev_resume, sc->eh_resume);
+#endif
+
 	bus_space_unmap(sc->bus_tag, sc->smu_space, SMU_MEM_SIZE);
 	bus_space_unmap(sc->bus_tag, sc->reg_space, SMU_MEM_SIZE);
 

sys/dev/amdsmu/amdsmu.h

@@ -6,11 +6,13 @@
  * This software was developed by Aymeric Wibo <obiwac@freebsd.org>
  * under sponsorship from the FreeBSD Foundation.
  */
+
 #ifndef _AMDSMU_H_
 #define	_AMDSMU_H_
 
 #include <sys/param.h>
 #include <sys/bus.h>
+#include <sys/eventhandler.h>
 #include <sys/kernel.h>
 #include <machine/bus.h>
 #include <x86/cputypes.h>
@@ -60,6 +62,9 @@ struct amdsmu_softc {
 	struct sysctl_ctx_list	*sysctlctx;
 	struct sysctl_oid	*sysctlnode;
 
+	struct eventhandler_entry	*eh_suspend;
+	struct eventhandler_entry	*eh_resume;
+
 	struct resource		*res;
 	bus_space_tag_t 	bus_tag;
 
@@ -72,8 +77,10 @@ struct amdsmu_softc {
 	uint32_t		active_ip_blocks;
 	struct sysctl_oid	*ip_blocks_sysctlnode;
 	size_t			ip_block_count;
-	struct sysctl_oid	*ip_block_sysctlnodes[nitems(amdsmu_ip_blocks_names)];
-	bool			ip_blocks_active[nitems(amdsmu_ip_blocks_names)];
+	struct sysctl_oid	*ip_block_sysctlnodes[
+				    nitems(amdsmu_ip_blocks_names)];
+	bool			ip_blocks_active[
+				    nitems(amdsmu_ip_blocks_names)];
 
 	bus_space_handle_t	metrics_space;
 	struct amdsmu_metrics	metrics;

sys/dev/amdsmu/amdsmu_reg.h

@@ -45,6 +45,7 @@ enum amdsmu_res {
 
 enum amdsmu_msg {
 	SMU_MSG_GETSMUVERSION		= 0x02,
+	SMU_MSG_SLEEP_HINT		= 0x03,
 	SMU_MSG_LOG_GETDRAM_ADDR_HI	= 0x04,
 	SMU_MSG_LOG_GETDRAM_ADDR_LO	= 0x05,
 	SMU_MSG_LOG_START		= 0x06,

sys/modules/amdsmu/Makefile

@@ -9,6 +9,7 @@
 
 KMOD=	amdsmu
 SRCS=	amdsmu.c
-SRCS+=	bus_if.h device_if.h pci_if.h
+SRCS+=	bus_if.h device_if.h pci_if.h \
+	opt_acpi.h
 
 .include <bsd.kmod.mk>