linux-kernel - [PATCH v4 1/3] bus: mhi: core: Clear devices when moving execution environments

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Message-Id: <1613701052-38885-2-git-send-email-bbhatt@codeaurora.org>
Date:   Thu, 18 Feb 2021 18:17:30 -0800
From:   Bhaumik Bhatt <bbhatt@...eaurora.org>
To:     manivannan.sadhasivam@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, linux-kernel@...r.kernel.org,
        loic.poulain@...aro.org, carl.yin@...ctel.com,
        naveen.kumar@...ctel.com, Bhaumik Bhatt <bbhatt@...eaurora.org>
Subject: [PATCH v4 1/3] bus: mhi: core: Clear devices when moving execution environments

When moving from SBL to mission mode execution environment, there
is no remove callback notification to MHI client drivers which
operate on SBL mode only. Client driver devices are being created
in SBL or AMSS(mission mode) and only destroyed after power down
or SYS_ERROR. If there exist any SBL-specific channels, those are
left open and client drivers are thus unaware of the new execution
environment where those channels cannot operate. Close the gap and
issue remove callbacks to SBL-specific client drivers once device
enters mission mode.

Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
---
 drivers/bus/mhi/core/main.c | 27 +++++++++++++++++++++++----
 drivers/bus/mhi/core/pm.c   |  3 +++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 4e0131b..58f1425 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -244,8 +244,10 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
 
 int mhi_destroy_device(struct device *dev, void *data)
 {
+	struct mhi_chan *ul_chan, *dl_chan;
 	struct mhi_device *mhi_dev;
 	struct mhi_controller *mhi_cntrl;
+	enum mhi_ee_type ee = MHI_EE_MAX;
 
 	if (dev->bus != &mhi_bus_type)
 		return 0;
@@ -257,6 +259,17 @@ int mhi_destroy_device(struct device *dev, void *data)
 	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
 		return 0;
 
+	ul_chan = mhi_dev->ul_chan;
+	dl_chan = mhi_dev->dl_chan;
+
+	/*
+	 * If execution environment is specified, remove only those devices that
+	 * started in them based on ee_mask for the channels as we move on to a
+	 * different execution environment
+	 */
+	if (data)
+		ee = *(enum mhi_ee_type *)data;
+
 	/*
 	 * For the suspend and resume case, this function will get called
 	 * without mhi_unregister_controller(). Hence, we need to drop the
@@ -264,11 +277,17 @@ int mhi_destroy_device(struct device *dev, void *data)
 	 * be sure that there will be no instances of mhi_dev left after
 	 * this.
 	 */
-	if (mhi_dev->ul_chan)
-		put_device(&mhi_dev->ul_chan->mhi_dev->dev);
+	if (ul_chan) {
+		if (ee != MHI_EE_MAX && !(ul_chan->ee_mask & BIT(ee)))
+			return 0;
+		put_device(&ul_chan->mhi_dev->dev);
+	}
 
-	if (mhi_dev->dl_chan)
-		put_device(&mhi_dev->dl_chan->mhi_dev->dev);
+	if (dl_chan) {
+		if (ee != MHI_EE_MAX && !(dl_chan->ee_mask & BIT(ee)))
+			return 0;
+		put_device(&dl_chan->mhi_dev->dev);
+	}
 
 	dev_dbg(&mhi_cntrl->mhi_dev->dev, "destroy device for chan:%s\n",
 		 mhi_dev->name);
diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index 681960c..8da8806 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -377,6 +377,7 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
 {
 	struct mhi_event *mhi_event;
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	enum mhi_ee_type ee = MHI_EE_MAX, current_ee = mhi_cntrl->ee;
 	int i, ret;
 
 	dev_dbg(dev, "Processing Mission Mode transition\n");
@@ -395,6 +396,8 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
 
 	wake_up_all(&mhi_cntrl->state_event);
 
+	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);
 
 	/* Force MHI to be in M0 state before continuing */
-- 
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