linux-kernel - [PATCH] bus: mhi: host: Add uevent support in MHI driver

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Message-ID: <20250822-uevent_vdev_next-20250821-v1-1-9ed3a8162194@quicinc.com>
Date: Fri, 22 Aug 2025 10:22:03 +0530
From: Vivek.Pernamitta@...cinc.com
To: Manivannan Sadhasivam <mani@...nel.org>
CC: <mhi@...ts.linux.dev>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Vivek Pernamitta <quic_vpernami@...cinc.com>
Subject: [PATCH] bus: mhi: host: Add uevent support in MHI driver

From: Vivek Pernamitta <quic_vpernami@...cinc.com>

Notify the MHI device's Execution Environment (EE) state via uevent,
enabling applications to receive real-time updates and take appropriate
actions based on the current state of MHI.

Signed-off-by: Vivek Pernamitta <quic_vpernami@...cinc.com>
---
Notify the MHI device's Execution Environment (EE) state via uevent,
enabling applications to receive real-time updates and take appropriate
actions based on the current state.

Signed-off-by:
---
Usage:

Enabling 16 virtual fucntions for SRIOV device QDU100 once device reached
mission mode from systemd service file

SUBSYSTEM=="mhi", ENV{EXEC_ENV}=="MISSION MODE", SUBSYSTEMS=="pci", ATTRS{device}=="0x0601",ATTR{../sriov_numvfs}="16"
---

---
 drivers/bus/mhi/host/internal.h |  1 +
 drivers/bus/mhi/host/main.c     |  1 +
 drivers/bus/mhi/host/pm.c       | 22 ++++++++++++++++++++++
 3 files changed, 24 insertions(+)

diff --git a/drivers/bus/mhi/host/internal.h b/drivers/bus/mhi/host/internal.h
index 034be33565b78eff9bdefd93faa4f3ce93825bad..d455f0bf00133775fa23882a727782275640e43b 100644
--- a/drivers/bus/mhi/host/internal.h
+++ b/drivers/bus/mhi/host/internal.h
@@ -403,6 +403,7 @@ int mhi_process_data_event_ring(struct mhi_controller *mhi_cntrl,
 				struct mhi_event *mhi_event, u32 event_quota);
 int mhi_process_ctrl_ev_ring(struct mhi_controller *mhi_cntrl,
 			     struct mhi_event *mhi_event, u32 event_quota);
+void mhi_uevent_notify(struct mhi_controller *mhi_cntrl, enum mhi_ee_type ee);
 
 /* ISR handlers */
 irqreturn_t mhi_irq_handler(int irq_number, void *dev);
diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 52bef663e182de157e50f64c1764a52545c70865..8615512743199a59a58c3756d9cc3407079cee7e 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -512,6 +512,7 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
 		if (mhi_cntrl->rddm_image && mhi_is_active(mhi_cntrl)) {
 			mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_EE_RDDM);
 			mhi_cntrl->ee = ee;
+			mhi_uevent_notify(mhi_cntrl, mhi_cntrl->ee);
 			wake_up_all(&mhi_cntrl->state_event);
 		}
 		break;
diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
index 33d92bf2fc3ed48db5f7fe80e4f0ef9fe2d2f2ab..1b849f334c49e52636821ed7587865a9254e9118 100644
--- a/drivers/bus/mhi/host/pm.c
+++ b/drivers/bus/mhi/host/pm.c
@@ -418,6 +418,7 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
 	device_for_each_child(&mhi_cntrl->mhi_dev->dev, &current_ee,
 			      mhi_destroy_device);
 	mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_EE_MISSION_MODE);
+	mhi_uevent_notify(mhi_cntrl, mhi_cntrl->ee);
 
 	/* Force MHI to be in M0 state before continuing */
 	ret = __mhi_device_get_sync(mhi_cntrl);
@@ -631,6 +632,8 @@ static void mhi_pm_sys_error_transition(struct mhi_controller *mhi_cntrl)
 	/* Wake up threads waiting for state transition */
 	wake_up_all(&mhi_cntrl->state_event);
 
+	mhi_uevent_notify(mhi_cntrl, mhi_cntrl->ee);
+
 	if (MHI_REG_ACCESS_VALID(prev_state)) {
 		/*
 		 * If the device is in PBL or SBL, it will only respond to
@@ -829,6 +832,8 @@ void mhi_pm_st_worker(struct work_struct *work)
 			mhi_create_devices(mhi_cntrl);
 			if (mhi_cntrl->fbc_download)
 				mhi_download_amss_image(mhi_cntrl);
+
+			mhi_uevent_notify(mhi_cntrl, mhi_cntrl->ee);
 			break;
 		case DEV_ST_TRANSITION_MISSION_MODE:
 			mhi_pm_mission_mode_transition(mhi_cntrl);
@@ -838,6 +843,7 @@ void mhi_pm_st_worker(struct work_struct *work)
 			mhi_cntrl->ee = MHI_EE_FP;
 			write_unlock_irq(&mhi_cntrl->pm_lock);
 			mhi_create_devices(mhi_cntrl);
+			mhi_uevent_notify(mhi_cntrl, mhi_cntrl->ee);
 			break;
 		case DEV_ST_TRANSITION_READY:
 			mhi_ready_state_transition(mhi_cntrl);
@@ -1240,6 +1246,8 @@ static void __mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful,
 	write_unlock_irq(&mhi_cntrl->pm_lock);
 	mutex_unlock(&mhi_cntrl->pm_mutex);
 
+	mhi_uevent_notify(mhi_cntrl, mhi_cntrl->ee);
+
 	if (destroy_device)
 		mhi_queue_state_transition(mhi_cntrl,
 					   DEV_ST_TRANSITION_DISABLE_DESTROY_DEVICE);
@@ -1338,3 +1346,17 @@ void mhi_device_put(struct mhi_device *mhi_dev)
 	read_unlock_bh(&mhi_cntrl->pm_lock);
 }
 EXPORT_SYMBOL_GPL(mhi_device_put);
+
+void mhi_uevent_notify(struct mhi_controller *mhi_cntrl, enum mhi_ee_type ee)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	char *buf[2];
+	int ret;
+
+	buf[0] = kasprintf(GFP_KERNEL, "EXEC_ENV=%s", TO_MHI_EXEC_STR(ee));
+	buf[1] = NULL;
+
+	ret = kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, buf);
+	if (ret)
+		dev_err(dev, "Failed to send %s uevent\n", TO_MHI_EXEC_STR(ee));
+}

---
base-commit: 7fa4d8dc380fbd81a9d702a855c50690c9c6442c
change-id: 20250822-uevent_vdev_next-20250821-dec34b0a7522

Best regards,
-- 
Vivek Pernamitta <<quic_vpernami@...cinc.com>>