soc: apple: retain the live J613 MTP through s2idle

drivers/hid/dockchannel-hid/dockchannel-hid.c

@@ -224,6 +224,9 @@ struct dockchannel_hid {
 
 	/* Workqueue to asynchronously create HID devices */
 	struct workqueue_struct *new_iface_wq;
+
+	/* Held while one frame is written to the shared TX FIFO */
+	struct mutex tx_mutex;
 };
 
 static ssize_t apple_layout_id_show(struct device *dev,
@@ -347,7 +350,7 @@ static bool dchid_verify_checksum(struct dchid_hdr *hdr, void *data, u32 *checks
 	return *checksum == U32_MAX;
 }
 
-static int dchid_send(struct dchid_iface *iface, u32 flags, void *msg, size_t size)
+static int dchid_send_frame(struct dchid_iface *iface, u32 flags, void *msg, size_t size)
 {
 	u32 checksum = 0xffffffff;
 	size_t wsize = round_down(size, 4);
@@ -398,6 +401,23 @@ static int dchid_send(struct dchid_iface *iface, u32 flags, void *msg, size_t si
 	return 0;
 }
 
+/*
+ * A frame goes out as several FIFO writes, and each interface has its own
+ * output lock, so frames for two interfaces could interleave in the shared
+ * FIFO. The MTP firmware then fails the frame checksum and crashes
+ * ("[dock ch tl]: xsum err"). Write whole frames only.
+ */
+static int dchid_send(struct dchid_iface *iface, u32 flags, void *msg, size_t size)
+{
+	struct dockchannel_hid *dchid = iface->dchid;
+	int ret;
+
+	mutex_lock(&dchid->tx_mutex);
+	ret = dchid_send_frame(iface, flags, msg, size);
+	mutex_unlock(&dchid->tx_mutex);
+	return ret;
+}
+
 static int dchid_cmd(struct dchid_iface *iface, u32 type, u32 req,
 		     void *data, size_t size, void *resp_buf, size_t resp_size)
 {
@@ -1583,6 +1603,7 @@ static int dockchannel_hid_probe(struct platform_device *pdev)
 	}
 
 	dchid->dev = dev;
+	mutex_init(&dchid->tx_mutex);
 	stm = device_get_named_child_node(dev, "stm");
 	dchid->id_ready = !stm || !fwnode_device_is_available(stm);
 	fwnode_handle_put(stm);

drivers/iommu/apple-dart.c

@@ -42,6 +42,7 @@
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/pm_wakeup.h>
 #include <linux/slab.h>
 #include <linux/soc/apple/tunable.h>
 #include <linux/string.h>
@@ -356,6 +357,7 @@ struct apple_dart {
 	u32 supports_bypass : 1;
 	/* J613 MTP keeps issuing DMA in the boot loader identity domain. */
 	bool live_mtp;
+	bool live_mtp_sleep;
 	u32 four_level : 1;
 	u32 locked : 1;
 	u32 tunneled : 1;
@@ -5658,13 +5660,9 @@ static __maybe_unused int apple_dart_suspend(struct device *dev)
 {
 	struct apple_dart *dart = dev_get_drvdata(dev);
 
-	/*
-	 * The adopted MTP keeps issuing DMA through its firmware bypass.
-	 * Like its RTKit helper, admit only suspend-to-idle: leave the DART
-	 * untouched while that live session and its power domain stay on.
-	 */
+	/* Runtime PM may not stop the live MTP; system sleep uses its own callbacks. */
 	if (dart->live_mtp)
-		return pm_suspend_target_state == PM_SUSPEND_TO_IDLE ? 0 : -EBUSY;
+		return -EBUSY;
 
 	dart->tunnel_state_restored = false;
 	if (READ_ONCE(dart->commands_gated))
@@ -5884,7 +5882,45 @@ static __maybe_unused int apple_dart_resume(struct device *dev)
 	return ret;
 }
 
-static DEFINE_RUNTIME_DEV_PM_OPS(apple_dart_pm_ops, apple_dart_suspend, apple_dart_resume, NULL);
+/* The adopted MTP stays live: system s2idle must retain, never reset it. */
+static int apple_dart_system_suspend(struct device *dev)
+{
+	struct apple_dart *dart = dev_get_drvdata(dev);
+
+	if (!dart->live_mtp)
+		return pm_runtime_force_suspend(dev);
+	if (pm_suspend_target_state != PM_SUSPEND_TO_IDLE)
+		return -EBUSY;
+	if (apple_dart_readl(dart, DART_TCR(dart, 1)) != dart->hw->tcr_bypass)
+		return -EIO;
+	/* PMGR's ACTIVE_WAKEUP domains and their ancestors must stay powered. */
+	device_set_awake_path(dev);
+	dart->live_mtp_sleep = true;
+	dev_dbg(dev, "live MTP s2idle: retaining clocks, supplier power and bypass stream 1\n");
+	return 0;
+}
+
+static int apple_dart_system_resume(struct device *dev)
+{
+	struct apple_dart *dart = dev_get_drvdata(dev);
+
+	if (!dart->live_mtp)
+		return pm_runtime_force_resume(dev);
+	if (!dart->live_mtp_sleep)
+		return 0;
+	dart->live_mtp_sleep = false;
+	if (apple_dart_readl(dart, DART_TCR(dart, 1)) != dart->hw->tcr_bypass) {
+		dev_err(dev, "live MTP bypass lost across s2idle; refusing reset of inherited DMA\n");
+		return -EIO;
+	}
+	dev_dbg(dev, "live MTP s2idle: bypass retained; no reset or invalidate\n");
+	return 0;
+}
+
+static const struct dev_pm_ops apple_dart_pm_ops = {
+	RUNTIME_PM_OPS(apple_dart_suspend, apple_dart_resume, NULL)
+	SYSTEM_SLEEP_PM_OPS(apple_dart_system_suspend, apple_dart_system_resume)
+};
 
 static const struct of_device_id apple_dart_of_match[] = {
 	{ .compatible = "apple,t8103-dart", .data = &apple_dart_hw_t8103 },

drivers/soc/apple/rtkit-helper.c

@@ -13,6 +13,7 @@
 #include <linux/of_platform.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/platform_device.h>
+#include <linux/pm_wakeup.h>
 #include <linux/soc/apple/rtkit.h>
 #include <linux/soc/apple/rtkit-helper.h>
 #include <linux/soc/apple/t8132.h>
@@ -384,9 +385,29 @@ static int __maybe_unused apple_rtkit_helper_suspend(struct device *dev)
 {
 	struct apple_rtkit_helper *helper = dev_get_drvdata(dev);
 
-	/* Only suspend-to-idle has a verified live-session retention contract. */
 	if (helper->adopted && pm_suspend_target_state != PM_SUSPEND_TO_IDLE)
 		return -EBUSY;
+	if (!helper->adopted || !of_machine_is_compatible("apple,j613"))
+		return 0;
+	if (!(readl(helper->asc_base + APPLE_ASC_CPU_CONTROL) & APPLE_ASC_CPU_CONTROL_RUN))
+		return -EHOSTDOWN;
+	/* mtp-live-v1 cannot be restarted: keep its ASC suppliers awake. */
+	device_set_awake_path(dev);
+	dev_dbg(dev, "adopted MTP s2idle: retaining ASC RUN and firmware session\n");
+	return 0;
+}
+
+static int __maybe_unused apple_rtkit_helper_resume(struct device *dev)
+{
+	struct apple_rtkit_helper *helper = dev_get_drvdata(dev);
+
+	if (!helper->adopted || !of_machine_is_compatible("apple,j613"))
+		return 0;
+	if (!(readl(helper->asc_base + APPLE_ASC_CPU_CONTROL) & APPLE_ASC_CPU_CONTROL_RUN)) {
+		dev_err(dev, "adopted MTP lost ASC RUN; refusing firmware restart\n");
+		return -EHOSTDOWN;
+	}
+	dev_dbg(dev, "adopted MTP s2idle: ASC RUN retained, no INIT\n");
 	return 0;
 }
 
@@ -400,6 +421,7 @@ static int __maybe_unused apple_rtkit_helper_freeze(struct device *dev)
 
 static const struct dev_pm_ops apple_rtkit_helper_pm_ops = {
 	.suspend = pm_sleep_ptr(apple_rtkit_helper_suspend),
+	.resume = pm_sleep_ptr(apple_rtkit_helper_resume),
 	.freeze = pm_sleep_ptr(apple_rtkit_helper_freeze),
 	.poweroff = pm_sleep_ptr(apple_rtkit_helper_freeze),
 };

tools/asahi/j613-mtp-s2idle-tests.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-only
+"""Actual system PM callbacks, synthetic register/PM boundaries; no device access."""
+from pathlib import Path
+import subprocess,tempfile
+R=Path(__file__).resolve().parents[2]
+def fn(s,n):
+ normalized=s.replace('static int __maybe_unused ', 'static int ');a=normalized.index('static int '+n+'(');b=normalized.index('\n}',a)+2;return normalized[a:b]
+s=(R/'drivers/iommu/apple-dart.c').read_text();h=(R/'drivers/soc/apple/rtkit-helper.c').read_text()
+assert 'if (dart->live_mtp)\n\t\treturn -EBUSY;' in s
+pre=r'''
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <errno.h>
+#define dev_dbg(...) ((void)0)
+#define dev_err(...) ((void)0)
+#define DART_TCR(d,s) (s)
+#define APPLE_ASC_CPU_CONTROL 0x44
+#define APPLE_ASC_CPU_CONTROL_RUN 16
+#define PM_SUSPEND_TO_IDLE 1
+static int pm_suspend_target_state=1;
+struct device {void *data;bool awake;};
+struct hw {unsigned tcr_bypass;};
+struct apple_dart {bool live_mtp,live_mtp_sleep;struct hw *hw;unsigned tcr;};
+struct apple_rtkit_helper {bool adopted;unsigned char *asc_base;};
+static void *dev_get_drvdata(struct device *d){return d->data;}
+static unsigned apple_dart_readl(struct apple_dart *d,unsigned sid){assert(sid==1);return d->tcr;}
+static void device_set_awake_path(struct device *d){d->awake=true;}
+static unsigned forced_suspend,forced_resume;
+static int pm_runtime_force_suspend(struct device *d){forced_suspend++;return 7;}
+static int pm_runtime_force_resume(struct device *d){forced_resume++;return 8;}
+static bool of_machine_is_compatible(const char *s){return true;}
+static unsigned readl(void *p){return *(unsigned *)p;}
+'''
+body=fn(s,'apple_dart_system_suspend')+fn(s,'apple_dart_system_resume')+fn(h,'apple_rtkit_helper_suspend')+fn(h,'apple_rtkit_helper_resume')
+for forbidden in ['writel','hw_reset','invalidate_tlb','apple_rtkit_wake','apple_rtkit_boot','apple_rtkit_quiesce']:
+ assert forbidden not in body,forbidden
+checks=r'''
+int main(void){
+ struct hw hw={.tcr_bypass=3};struct apple_dart a={.live_mtp=true,.hw=&hw,.tcr=3};struct device d={.data=&a};
+ assert(!apple_dart_system_suspend(&d)&&d.awake&&a.live_mtp_sleep);
+ assert(!apple_dart_system_resume(&d)&&!a.live_mtp_sleep&&a.tcr==3&&!forced_suspend&&!forced_resume);
+ // Abort unwind is the same retained transaction, and can be repeated.
+ assert(!apple_dart_system_suspend(&d));assert(!apple_dart_system_resume(&d));
+ pm_suspend_target_state=2;assert(apple_dart_system_suspend(&d)==-EBUSY);pm_suspend_target_state=1;
+ a.tcr=0;assert(apple_dart_system_suspend(&d)==-EIO);a.tcr=3;
+ assert(!apple_dart_system_suspend(&d));a.tcr=0;assert(apple_dart_system_resume(&d)==-EIO&&a.tcr==0);
+ a.live_mtp=false;assert(apple_dart_system_suspend(&d)==7&&apple_dart_system_resume(&d)==8);
+ unsigned regs[32]={0};struct apple_rtkit_helper h={.adopted=true,.asc_base=(void *)regs};d.data=&h;d.awake=false;
+ regs[0x44/4]=16;assert(!apple_rtkit_helper_suspend(&d)&&d.awake);assert(!apple_rtkit_helper_resume(&d));
+ regs[0x44/4]=0;assert(apple_rtkit_helper_resume(&d)==-EHOSTDOWN&&!regs[0x44/4]);
+ assert(apple_rtkit_helper_suspend(&d)==-EHOSTDOWN);
+ h.adopted=false;assert(!apple_rtkit_helper_suspend(&d)&&!apple_rtkit_helper_resume(&d));
+}
+'''
+with tempfile.TemporaryDirectory() as t:
+ p=Path(t)/'pm.c';p.write_text(pre+body+checks)
+ subprocess.run(['clang','-std=gnu11','-Wall','-Werror','-fsanitize=address,undefined',str(p),'-o',str(p.with_suffix(''))],check=True)
+ subprocess.run([str(p.with_suffix(''))],check=True)
+print('PASS actual MTP/DART system PM: retained normal/abort cycles, runtime delegation, non-s2idle refusal, lost bypass/RUN refuses without reset/INIT')