soc: apple: suspend-to-RAM on the M4 Max (T6041, J616c)

arch/arm64/boot/dts/apple/t6041-j614c-j616c.dtsi

@@ -33,6 +33,11 @@
 		sep = &sep;
 	};
 
+	/* Suspend-to-RAM at EL2 through aura's S2R mailbox; without the mailbox it stays out. */
+	t6041-sleep {
+		compatible = "apple,t6041-sleep";
+	};
+
 	chosen {
 		#address-cells = <2>;
 		#size-cells = <2>;

arch/arm64/boot/dts/apple/t6041.dtsi

@@ -445,3 +445,17 @@
 &{/opp-table-e/opp07} {
 	opp-microwatt = <531000>;
 };
+
+/*
+ * What the SEP's DART gets around a sleep, as offset and value: the writes T8140's has
+ * (t8140.dtsi), which the J616C has slept with. The SEP driver saves the DART with them
+ * before it tells the enclave to sleep at suspend.
+ */
+&sep_dart {
+	apple,sleep-prepare = <0x80 0xa102>, <0x704 0xffffffff>;
+	apple,sleep-restore = <0x210 0x0>, <0x20c 0x800005f5>,
+			      <0x220 0xf0f0f>, <0x224 0x80808>,
+			      <0x300 0x1>, <0x318 0x1>;
+	apple,sleep-restore-late = <0x80 0x8000>, <0x228 0x3f3f3f3f>,
+				   <0x22c 0x1010101>;
+};

drivers/bluetooth/hci_bcm4377.c

@@ -5,6 +5,7 @@
  * Copyright (C) The Asahi Linux Contributors
  */
 
+#include <linux/suspend.h>
 #include <linux/async.h>
 #include <linux/atomic.h>
 #include <linux/bitfield.h>
@@ -3168,6 +3169,19 @@ static int bcm4377_resume(struct device *dev)
 		bcm4377->wake_armed = false;
 	}
 
+	/*
+	 * A real sleep took the function's power: the firmware is gone, and every resume command
+	 * would only time out (two times 2 s inside the system resume, then the rebind anyway).
+	 * Skip them and rebind from the work queue; probe boots the firmware from scratch.
+	 */
+	if (pm_resume_via_firmware() && !bcm4377->dma_window_base) {
+		bcm4377->quiesced = false;
+		bcm4377->resume_powered = false;
+		WRITE_ONCE(bcm4377->setup_retry_blocked, false);
+		bcm4377_queue_rebind(bcm4377, "power lost in the sleep");
+		return 0;
+	}
+
 	if (bcm4377->quiesced) {
 		iowrite32(BCM4377_BAR0_SLEEP_CONTROL_UNQUIESCE,
 			  bcm4377->bar0 + BCM4377_BAR0_SLEEP_CONTROL);

drivers/gpu/drm/apple/apple_drv.c

@@ -1964,6 +1964,9 @@ static int apple_platform_suspend(struct device *dev)
 	if (apple && apple->dark_held)
 		return 0;
 
+	if (pm_suspend_via_firmware())
+		dcp_t6041_s2r_all(false);
+
 	if (apple && !apple->aborted) {
 		apple->s2r_skipped = apple_drm_firmware_stopped(apple);
 		if (!apple->s2r_skipped)
@@ -2009,6 +2012,9 @@ static int apple_platform_resume(struct device *dev)
 {
 	struct apple_drm_private *apple = dev_get_drvdata(dev);
 
+	/* Nothing if this suspend never took the display down. */
+	dcp_t6041_s2r_all(true);
+
 	if (!apple || apple->aborted || apple->s2r_skipped)
 		return 0;
 

drivers/gpu/drm/apple/dcp-internal.h

@@ -479,6 +479,8 @@ struct apple_dcp {
 	 */
 	bool ext_failsafe;
 	bool ext_dead;
+	/* T6041 S2R: this external DCP's firmware stop ran in a sleep of this boot */
+	bool t6041_ext_seen;
 	/*
 	 * A T6030 external processor in the main DRM device: the kernel starts
 	 * its firmware on first use, its modes come from the attached display.