J713 (M4 MacBook Air): suspend-to-idle

Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml

@@ -114,6 +114,13 @@ properties:
   resets:
     maxItems: 1
 
+  apple,hold-rx-in-sleep:
+    description:
+      Messages from this coprocessor need not wake the system. The OS may
+      leave them in the receive FIFO while the system sleeps and handle
+      them at resume.
+    type: boolean
+
   power-domains:
     minItems: 1
     maxItems: 2

Documentation/devicetree/bindings/power/apple,pmgr-pwrstate.yaml

@@ -22,6 +22,7 @@ allOf:
     then:
       properties:
         apple,firmware-owned: false
+        apple,sleep-retained: false
         apple,always-on: false
         apple,min-state: false
         apple,force-disable: false
@@ -106,6 +107,13 @@ properties:
       coprocessors' CPU domains.
     type: boolean
 
+  apple,sleep-retained:
+    description:
+      A coprocessor keeps running in this domain across system sleep with no
+      system-sleep callbacks of its own. The OS keeps the domain on during
+      system sleep. Runtime power management is unaffected.
+    type: boolean
+
   apple,firmware-owned:
     description:
       The boot loader hands over active hardware whose power domain remains

arch/arm64/boot/dts/apple/t8132-j713-gpu.dtsi

@@ -80,6 +80,8 @@
 		/* ASCWrap v6 contains the same mailbox aperture used by ASC v4. */
 		compatible = "apple,t8132-asc-mailbox", "apple,asc-mailbox-v4";
 		reg = <0x3 0x02608000 0x0 0x4000>;
+		/* Idle ring-service kicks need not wake the system. */
+		apple,hold-rx-in-sleep;
 		interrupt-parent = <&aic>;
 		interrupts = <AIC_IRQ 993 IRQ_TYPE_LEVEL_HIGH>,
 			     <AIC_IRQ 994 IRQ_TYPE_LEVEL_HIGH>,
@@ -95,6 +97,8 @@
 &ps_gfx {
 	status = "okay";
 	power-domains = <&gfx_tvm>;
+	/* The G16 firmware stays live across suspend-to-idle. */
+	apple,sleep-retained;
 };
 
 /* The existing report provider owns readiness for shared PMP commands. */

drivers/iommu/apple-dart.c

@@ -41,6 +41,7 @@
 #include <linux/slab.h>
 #include <linux/soc/apple/tunable.h>
 #include <linux/string.h>
+#include <linux/suspend.h>
 #include <linux/swab.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
@@ -311,6 +312,8 @@ struct apple_dart {
 	struct apple_dart_dcp *dcp;
 	struct apple_dart_dcp *frontend[2];
 	bool preserve_display;
+	/* Retained radio/display state left in place across suspend-to-idle. */
+	bool s2idle_kept;
 	/* Resources reachable by a retained domain outlive device removal. */
 	bool retained;
 	bool retained_mtp;
@@ -4718,10 +4721,23 @@ static const struct apple_dart_hw apple_dart_hw_t8110 = {
 	.ttbr_count = 1,
 };
 
+static void apple_dart_save_state(struct apple_dart *dart)
+{
+	unsigned int sid, idx;
+
+	for (sid = 0; sid < dart->num_streams; sid++) {
+		dart->save_tcr[sid] = apple_dart_readl(dart,
+						       DART_TCR(dart, sid));
+		for (idx = 0; idx < dart->hw->ttbr_count; idx++)
+			dart->save_ttbr[sid][idx] =
+				apple_dart_readl(dart,
+						 DART_TTBR(dart, sid, idx));
+	}
+}
+
 static __maybe_unused int apple_dart_suspend(struct device *dev)
 {
 	struct apple_dart *dart = dev_get_drvdata(dev);
-	unsigned int sid, idx;
 
 	dart->tunnel_state_restored = false;
 	if (READ_ONCE(dart->commands_gated))
@@ -4733,9 +4749,19 @@ static __maybe_unused int apple_dart_suspend(struct device *dev)
 	 */
 	if (dart->cold_ane)
 		return 0;
-	/* Neither retained radio nor display has a qualified suspend boundary. */
-	if (dart->managed_sids || dart->preserve_display || apple_dart_has_borrowed(dart))
-		return -EBUSY;
+	/*
+	 * Retained radio and display DMA has no suspend boundary of its own.
+	 * Suspend-to-idle leaves it running in place: these DARTs have no
+	 * power domain here, and the DCP keeps the display domains on. The
+	 * registers are saved only for resume to check.
+	 */
+	if (dart->managed_sids || dart->preserve_display || apple_dart_has_borrowed(dart)) {
+		if (pm_suspend_target_state != PM_SUSPEND_TO_IDLE)
+			return -EBUSY;
+		apple_dart_save_state(dart);
+		dart->s2idle_kept = true;
+		return 0;
+	}
 	/* The tunneled DART has no state to save when its domain stays on. */
 	if (dart->power_retained || dart->retained_mtp)
 		return 0;
@@ -4744,15 +4770,7 @@ static __maybe_unused int apple_dart_suspend(struct device *dev)
 	if (dart->locked)
 		return 0;
 
-	for (sid = 0; sid < dart->num_streams; sid++) {
-		dart->save_tcr[sid] = apple_dart_readl(dart,
-						       DART_TCR(dart, sid));
-		for (idx = 0; idx < dart->hw->ttbr_count; idx++)
-			dart->save_ttbr[sid][idx] =
-				apple_dart_readl(dart,
-						 DART_TTBR(dart, sid, idx));
-	}
-
+	apple_dart_save_state(dart);
 	return 0;
 }
 
@@ -4816,6 +4834,28 @@ static int apple_dart_invalidate_each_stream(struct apple_dart *dart)
 	return 0;
 }
 
+/*
+ * Resume of a DART whose live DMA stayed in place through suspend-to-idle. It
+ * cannot be restored from the saved copy. If the translations changed, the
+ * consumers' DMA is no longer what they set up: refuse their further use
+ * through the same paths as a translation fault before failing resume, since
+ * a resume error does not stop the PM core from resuming them.
+ */
+static int apple_dart_resume_retained(struct apple_dart *dart)
+{
+	if (!dart->s2idle_kept)
+		return -EBUSY;
+	dart->s2idle_kept = false;
+	if (apple_dart_state_retained(dart))
+		return 0;
+
+	dev_err(dart->dev, "retained DMA state lost in suspend-to-idle\n");
+	if (dart->managed_sids)
+		apple_dart_managed_quarantine(dart);
+	apple_dart_quarantine_borrowed(dart);
+	return -EIO;
+}
+
 static __maybe_unused int apple_dart_resume(struct device *dev)
 {
 	struct apple_dart *dart = dev_get_drvdata(dev);
@@ -4826,7 +4866,7 @@ static __maybe_unused int apple_dart_resume(struct device *dev)
 	if (dart->cold_ane)
 		return 0;
 	if (dart->managed_sids || dart->preserve_display || apple_dart_has_borrowed(dart))
-		return -EBUSY;
+		return apple_dart_resume_retained(dart);
 
 	/* PCIe-C restored these mappings before starting its downstream link. */
 	if (dart->tunnel_state_restored) {

drivers/pci/controller/pcie-apple.c

@@ -3638,8 +3638,12 @@ static int apple_pcie_suspend_noirq(struct device *dev)
 {
 	struct apple_pcie *pcie = apple_pcie_lookup(dev);
 
+	/*
+	 * The managed radio has no suspend boundary of its own; suspend-to-idle
+	 * leaves it in place like any other internal port (no power domain).
+	 */
 	if (pcie->managed_sids)
-		return -EBUSY;
+		return pm_suspend_target_state == PM_SUSPEND_TO_IDLE ? 0 : -EBUSY;
 	if (!pcie->hw->tunneled)
 		return 0;
 	pcie->reset_on_resume = false;

drivers/pmdomain/apple/pmgr-pwrstate.c

@@ -54,6 +54,8 @@ struct apple_pmgr_ps {
 	bool externally_clocked;
 	bool system_sleep;
 	bool firmware_owned;
+	/* apple,sleep-retained: kept on while the system sleeps */
+	bool sleep_retained;
 	/* Never enable automatic power management (apple,no-auto-pm). */
 	bool no_auto_pm;
 	bool inherited_on;
@@ -263,6 +265,9 @@ static int apple_pmgr_ps_power_off(struct generic_pm_domain *genpd)
 		return 0;
 	if (ps->inherited_on)
 		return -EBUSY;
+	/* A live coprocessor keeps this domain through system sleep. */
+	if (ps->sleep_retained && ps->system_sleep)
+		return -EBUSY;
 
 	ret = apple_pmgr_ps_set(genpd, APPLE_PMGR_PS_PWRGATE, false);
 	if (ret)
@@ -524,14 +529,16 @@ static int apple_pmgr_ps_probe(struct platform_device *pdev)
 	 * vote and never read, reset or change the hardware state.
 	 */
 	ps->firmware_owned = of_property_read_bool(node, "apple,firmware-owned");
+	ps->sleep_retained = of_property_read_bool(node, "apple,sleep-retained");
 	/*
 	 * Only T8132 hands over inherited-on domains with this contract. Older
 	 * M3 device trees carry the property with another meaning; keep them
 	 * as they were.
 	 */
 	ps->inherited_on = t8132 && of_property_read_bool(node, "apple,inherited-on");
 	if (ps->inherited_on &&
-	    (ps->firmware_owned || of_property_present(node, "apple,min-state") ||
+	    (ps->firmware_owned || ps->sleep_retained ||
+	     of_property_present(node, "apple,min-state") ||
 	     of_property_present(node, "apple,always-on") ||
 	     of_property_present(node, "apple,force-disable") ||
 	     of_property_present(node, "apple,force-reset") ||

drivers/soc/apple/mailbox.c

@@ -780,6 +780,7 @@ static int apple_mbox_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	mbox->dev = &pdev->dev;
+	mbox->hold_rx_in_sleep = of_property_read_bool(dev->of_node, "apple,hold-rx-in-sleep");
 	mbox->hw = of_device_get_match_data(dev);
 	if (!mbox->hw)
 		return -EINVAL;
@@ -1133,10 +1134,39 @@ static const struct of_device_id apple_mbox_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, apple_mbox_of_match);
 
+/*
+ * The receive IRQ is IRQF_NO_SUSPEND, so each message wakes a CPU out of
+ * suspend-to-idle. A coprocessor whose messages need not wake the system
+ * keeps them in the FIFO until resume. The mailbox is a supplier of its
+ * consumer, so this runs after the consumer suspended and before it resumes.
+ */
+static int apple_mbox_suspend_noirq(struct device *dev)
+{
+	struct apple_mbox *mbox = dev_get_drvdata(dev);
+
+	if (mbox && mbox->hold_rx_in_sleep)
+		apple_mbox_hold_rx(mbox);
+	return 0;
+}
+
+static int apple_mbox_resume_noirq(struct device *dev)
+{
+	struct apple_mbox *mbox = dev_get_drvdata(dev);
+
+	if (mbox && mbox->hold_rx_in_sleep)
+		apple_mbox_release_rx(mbox);
+	return 0;
+}
+
+static const struct dev_pm_ops apple_mbox_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(apple_mbox_suspend_noirq, apple_mbox_resume_noirq)
+};
+
 static struct platform_driver apple_mbox_driver = {
 	.driver = {
 		.name = "apple-mailbox",
 		.of_match_table = apple_mbox_of_match,
+		.pm = pm_sleep_ptr(&apple_mbox_pm_ops),
 	},
 	.probe = apple_mbox_probe,
 	.remove = apple_mbox_remove,

include/linux/soc/apple/mailbox.h

@@ -64,6 +64,8 @@ struct apple_mbox {
 	bool active;
 	bool ascwrap_v6_cpu_running;
 	bool removing;
+	/* apple,hold-rx-in-sleep: receive IRQ masked across system sleep */
+	bool hold_rx_in_sleep;
 
 	int irq_recv_not_empty;
 	int irq_send_empty; /* < 0: no send-empty IRQ, TX polls */