Message-ID: <20251125083746.2605721-1-b-padhi@ti.com>
Date: Tue, 25 Nov 2025 14:07:46 +0530
From: Beleswar Padhi <b-padhi@...com>
To: <andersson@...nel.org>, <mathieu.poirier@...aro.org>
CC: <richard.genoud@...tlin.com>, <afd@...com>, <hnagalla@...com>,
	<jm@...com>, <u-kumar1@...com>, <jan.kiszka@...mens.com>,
	<christophe.jaillet@...adoo.fr>, <b-padhi@...com>,
	<linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] remoteproc: k3: support for graceful shutdown of remote cores

From: Richard Genoud <richard.genoud@...tlin.com>

Introduce software IPC handshake between the host running Linux and the
remote processors to gracefully stop/reset the remote core.

Upon a stop request, remoteproc driver sends a RP_MBOX_SHUTDOWN mailbox
message to the remotecore.
The remote core is expected to:
- relinquish all the resources acquired through Device Manager (DM)
- disable its interrupts
- send back a mailbox acknowledgment RP_MBOX_SHUDOWN_ACK
- enter WFI state.

Meanwhile, the K3 remoteproc driver does:
- wait for the RP_MBOX_SHUTDOWN_ACK from the remote core
- wait for the remoteproc to enter WFI state
- reset the remote core through device manager

Based on work from: Hari Nagalla <hnagalla@...com>

Signed-off-by: Richard Genoud <richard.genoud@...tlin.com>
[b-padhi@...com: Extend support to all rprocs]
Signed-off-by: Beleswar Padhi <b-padhi@...com>
---
v2: Changelog:
1. Extend graceful shutdown support for all rprocs (R5, DSP, M4)
2. Halt core only if SHUTDOWN_ACK is received from rproc and it has
entered WFI state.
3. Convert return type of is_core_in_wfi() to bool. Works better with
readx_poll_timeout() condition.
4. Cast RP_MBOX_SHUTDOWN to uintptr_t to suppress compiler warnings
when void* is 64 bit.
5. Wrapped Graceful shutdown code in the form of notify_shutdown_rproc
function.
6. Updated commit message to fix minor typos and such.

Link to v1:
https://lore.kernel.org/all/20240621150058.319524-5-richard.genoud@bootlin.com/

Testing done:
1. Tested Boot across all TI K3 EVM/SK boards.
2. Tested IPC on all TI K3 J7* EVM/SK boards (& AM62x SK).
4. Tested R5 rprocs can now be shutdown and powered back on
from userspace.
3. Tested that each patch in the series generates no new
warnings/errors.

 drivers/remoteproc/omap_remoteproc.h      |  9 ++-
 drivers/remoteproc/ti_k3_common.c         | 72 +++++++++++++++++++++++
 drivers/remoteproc/ti_k3_common.h         |  4 ++
 drivers/remoteproc/ti_k3_dsp_remoteproc.c |  2 +
 drivers/remoteproc/ti_k3_m4_remoteproc.c  |  2 +
 drivers/remoteproc/ti_k3_r5_remoteproc.c  |  5 ++
 6 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/drivers/remoteproc/omap_remoteproc.h b/drivers/remoteproc/omap_remoteproc.h
index 828e13256c023..c008f11fa2a43 100644
--- a/drivers/remoteproc/omap_remoteproc.h
+++ b/drivers/remoteproc/omap_remoteproc.h
@@ -42,6 +42,11 @@
  * @RP_MBOX_SUSPEND_CANCEL: a cancel suspend response from a remote processor
  * on a suspend request
  *
+ * @RP_MBOX_SHUTDOWN: shutdown request for the remote processor
+ *
+ * @RP_MBOX_SHUTDOWN_ACK: successful response from remote processor for a
+ * shutdown request. The remote processor should be in WFI state short after.
+ *
  * Introduce new message definitions if any here.
  *
  * @RP_MBOX_END_MSG: Indicates end of known/defined messages from remote core
@@ -59,7 +64,9 @@ enum omap_rp_mbox_messages {
 	RP_MBOX_SUSPEND_SYSTEM	= 0xFFFFFF11,
 	RP_MBOX_SUSPEND_ACK	= 0xFFFFFF12,
 	RP_MBOX_SUSPEND_CANCEL	= 0xFFFFFF13,
-	RP_MBOX_END_MSG		= 0xFFFFFF14,
+	RP_MBOX_SHUTDOWN	= 0xFFFFFF14,
+	RP_MBOX_SHUTDOWN_ACK	= 0xFFFFFF15,
+	RP_MBOX_END_MSG		= 0xFFFFFF16,
 };
 
 #endif /* _OMAP_RPMSG_H */
diff --git a/drivers/remoteproc/ti_k3_common.c b/drivers/remoteproc/ti_k3_common.c
index 56b71652e449f..5d469f65115c3 100644
--- a/drivers/remoteproc/ti_k3_common.c
+++ b/drivers/remoteproc/ti_k3_common.c
@@ -18,7 +18,9 @@
  *	Hari Nagalla <hnagalla@...com>
  */
 
+#include <linux/delay.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/mailbox_client.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
@@ -69,6 +71,10 @@ void k3_rproc_mbox_callback(struct mbox_client *client, void *data)
 	case RP_MBOX_ECHO_REPLY:
 		dev_info(dev, "received echo reply from %s\n", rproc->name);
 		break;
+	case RP_MBOX_SHUTDOWN_ACK:
+		dev_dbg(dev, "received shutdown_ack from %s\n", rproc->name);
+		complete(&kproc->shutdown_complete);
+		break;
 	default:
 		/* silently handle all other valid messages */
 		if (msg >= RP_MBOX_READY && msg < RP_MBOX_END_MSG)
@@ -188,6 +194,67 @@ int k3_rproc_request_mbox(struct rproc *rproc)
 }
 EXPORT_SYMBOL_GPL(k3_rproc_request_mbox);
 
+/**
+ * is_core_in_wfi - Utility function to check core status
+ * @kproc: remote core pointer used for checking core status
+ *
+ * This utility function is invoked by the shutdown sequence to ensure
+ * the remote core is in wfi, before asserting a reset.
+ */
+bool is_core_in_wfi(struct k3_rproc *kproc)
+{
+	int ret;
+	u64 boot_vec;
+	u32 cfg, ctrl, stat;
+
+	ret = ti_sci_proc_get_status(kproc->tsp, &boot_vec, &cfg, &ctrl, &stat);
+	if (ret)
+		return false;
+
+	return (bool)(stat & PROC_BOOT_STATUS_FLAG_CPU_WFI);
+}
+EXPORT_SYMBOL_GPL(is_core_in_wfi);
+
+/**
+ * notify_shutdown_rproc - Prepare the remoteproc for a shutdown
+ * @kproc: remote core pointer used for sending mbox msg
+ *
+ * This function sends the shutdown prepare message to remote processor and
+ * waits for an ACK. Further, it checks if the remote processor has entered
+ * into WFI mode. It is invoked in shutdown sequence to ensure the rproc
+ * has relinquished its resources before asserting a reset, so the shutdown
+ * happens cleanly.
+ */
+int notify_shutdown_rproc(struct k3_rproc *kproc)
+{
+	bool wfi_status = false;
+	int ret;
+
+	reinit_completion(&kproc->shutdown_complete);
+
+	ret = mbox_send_message(kproc->mbox, (void *)(uintptr_t)RP_MBOX_SHUTDOWN);
+	if (ret < 0) {
+		dev_err(kproc->dev, "PM mbox_send_message failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = wait_for_completion_timeout(&kproc->shutdown_complete,
+					  msecs_to_jiffies(5000));
+	if (ret == 0) {
+		dev_err(kproc->dev, "%s: timeout waiting for rproc completion event\n",
+			__func__);
+		return -EBUSY;
+	}
+
+	ret = readx_poll_timeout(is_core_in_wfi, kproc, wfi_status, wfi_status,
+				 200, 2000);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(notify_shutdown_rproc);
+
 /*
  * The K3 DSP and M4 cores have a local reset that affects only the CPU, and a
  * generic module reset that powers on the device and allows the internal
@@ -288,6 +355,11 @@ EXPORT_SYMBOL_GPL(k3_rproc_start);
 int k3_rproc_stop(struct rproc *rproc)
 {
 	struct k3_rproc *kproc = rproc->priv;
+	int ret;
+
+	ret = notify_shutdown_rproc(kproc);
+	if (ret)
+		return ret;
 
 	return k3_rproc_reset(kproc);
 }
diff --git a/drivers/remoteproc/ti_k3_common.h b/drivers/remoteproc/ti_k3_common.h
index aee3c28dbe510..2a025f4894b82 100644
--- a/drivers/remoteproc/ti_k3_common.h
+++ b/drivers/remoteproc/ti_k3_common.h
@@ -22,6 +22,7 @@
 #define REMOTEPROC_TI_K3_COMMON_H
 
 #define KEYSTONE_RPROC_LOCAL_ADDRESS_MASK	(SZ_16M - 1)
+#define PROC_BOOT_STATUS_FLAG_CPU_WFI		0x00000002
 
 /**
  * struct k3_rproc_mem - internal memory structure
@@ -92,6 +93,7 @@ struct k3_rproc {
 	u32 ti_sci_id;
 	struct mbox_chan *mbox;
 	struct mbox_client client;
+	struct completion shutdown_complete;
 	void *priv;
 };
 
@@ -115,4 +117,6 @@ int k3_rproc_of_get_memories(struct platform_device *pdev,
 void k3_mem_release(void *data);
 int k3_reserved_mem_init(struct k3_rproc *kproc);
 void k3_release_tsp(void *data);
+bool is_core_in_wfi(struct k3_rproc *kproc);
+int notify_shutdown_rproc(struct k3_rproc *kproc);
 #endif /* REMOTEPROC_TI_K3_COMMON_H */
diff --git a/drivers/remoteproc/ti_k3_dsp_remoteproc.c b/drivers/remoteproc/ti_k3_dsp_remoteproc.c
index d6ceea6dc920e..156ae09d8ee25 100644
--- a/drivers/remoteproc/ti_k3_dsp_remoteproc.c
+++ b/drivers/remoteproc/ti_k3_dsp_remoteproc.c
@@ -133,6 +133,8 @@ static int k3_dsp_rproc_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	init_completion(&kproc->shutdown_complete);
+
 	ret = k3_rproc_of_get_memories(pdev, kproc);
 	if (ret)
 		return ret;
diff --git a/drivers/remoteproc/ti_k3_m4_remoteproc.c b/drivers/remoteproc/ti_k3_m4_remoteproc.c
index 3a11fd24eb52b..64d99071279b0 100644
--- a/drivers/remoteproc/ti_k3_m4_remoteproc.c
+++ b/drivers/remoteproc/ti_k3_m4_remoteproc.c
@@ -90,6 +90,8 @@ static int k3_m4_rproc_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	init_completion(&kproc->shutdown_complete);
+
 	ret = k3_rproc_of_get_memories(pdev, kproc);
 	if (ret)
 		return ret;
diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
index 04f23295ffc10..8748dc6089cc2 100644
--- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
+++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
@@ -533,6 +533,10 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
 	struct k3_r5_cluster *cluster = core->cluster;
 	int ret;
 
+	ret = notify_shutdown_rproc(kproc);
+	if (ret)
+		return ret;
+
 	/* halt all applicable cores */
 	if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
 		list_for_each_entry(core, &cluster->cores, elem) {
@@ -1129,6 +1133,7 @@ static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
 			goto out;
 		}
 
+		init_completion(&kproc->shutdown_complete);
 init_rmem:
 		k3_r5_adjust_tcm_sizes(kproc);
 
-- 
2.34.1

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