linux-kernel - [PATCH 19/20] bus: mhi: ep: Add support for suspending and resuming channels

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Date:   Thu,  2 Dec 2021 17:05:51 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     mhi@...ts.linux.dev
Cc:     hemantk@...eaurora.org, bbhatt@...eaurora.org,
        quic_jhugo@...cinc.com, vinod.koul@...aro.org,
        bjorn.andersson@...aro.org, dmitry.baryshkov@...aro.org,
        skananth@...eaurora.org, vpernami@...eaurora.org,
        vbadigan@...eaurora.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH 19/20] bus: mhi: ep: Add support for suspending and resuming channels

Add support for suspending and resuming the channels in MHI endpoint stack.
The channels will be moved to the suspended state during M3 state
transition and will be resumed during M0 transition.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/bus/mhi/ep/internal.h |  2 ++
 drivers/bus/mhi/ep/main.c     | 58 +++++++++++++++++++++++++++++++++++
 drivers/bus/mhi/ep/sm.c       |  4 +++
 3 files changed, 64 insertions(+)

diff --git a/drivers/bus/mhi/ep/internal.h b/drivers/bus/mhi/ep/internal.h
index 70626ef3799d..e0c36346c5b8 100644
--- a/drivers/bus/mhi/ep/internal.h
+++ b/drivers/bus/mhi/ep/internal.h
@@ -231,5 +231,7 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl);
 int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl);
 int mhi_ep_set_ready_state(struct mhi_ep_cntrl *mhi_cntrl);
 void mhi_ep_handle_syserr(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_resume_channels(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_suspend_channels(struct mhi_ep_cntrl *mhi_cntrl);
 
 #endif
diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index cc3da846ed36..930b5c2005d0 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -1176,6 +1176,64 @@ void mhi_ep_power_down(struct mhi_ep_cntrl *mhi_cntrl)
 }
 EXPORT_SYMBOL_GPL(mhi_ep_power_down);
 
+void mhi_ep_suspend_channels(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct mhi_ep_chan *mhi_chan;
+	u32 tmp;
+	int i;
+
+	for (i = 0; i < mhi_cntrl->max_chan; i++) {
+		mhi_chan = &mhi_cntrl->mhi_chan[i];
+
+		if (!mhi_chan->mhi_dev)
+			continue;
+
+		mutex_lock(&mhi_chan->lock);
+		/* Skip if the channel is not currently running */
+		tmp = mhi_cntrl->ch_ctx_cache[i].chcfg;
+		if (FIELD_GET(CHAN_CTX_CHSTATE_MASK, tmp) != MHI_CH_STATE_RUNNING) {
+			mutex_unlock(&mhi_chan->lock);
+			continue;
+		}
+
+		dev_dbg(&mhi_chan->mhi_dev->dev, "Suspending channel\n");
+		/* Set channel state to SUSPENDED */
+		tmp &= ~CHAN_CTX_CHSTATE_MASK;
+		tmp |= (MHI_CH_STATE_SUSPENDED << CHAN_CTX_CHSTATE_SHIFT);
+		mhi_cntrl->ch_ctx_cache[i].chcfg = tmp;
+		mutex_unlock(&mhi_chan->lock);
+	}
+}
+
+void mhi_ep_resume_channels(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct mhi_ep_chan *mhi_chan;
+	u32 tmp;
+	int i;
+
+	for (i = 0; i < mhi_cntrl->max_chan; i++) {
+		mhi_chan = &mhi_cntrl->mhi_chan[i];
+
+		if (!mhi_chan->mhi_dev)
+			continue;
+
+		mutex_lock(&mhi_chan->lock);
+		/* Skip if the channel is not currently suspended */
+		tmp = mhi_cntrl->ch_ctx_cache[i].chcfg;
+		if (FIELD_GET(CHAN_CTX_CHSTATE_MASK, tmp) != MHI_CH_STATE_SUSPENDED) {
+			mutex_unlock(&mhi_chan->lock);
+			continue;
+		}
+
+		dev_dbg(&mhi_chan->mhi_dev->dev, "Resuming channel\n");
+		/* Set channel state to RUNNING */
+		tmp &= ~CHAN_CTX_CHSTATE_MASK;
+		tmp |= (MHI_CH_STATE_RUNNING << CHAN_CTX_CHSTATE_SHIFT);
+		mhi_cntrl->ch_ctx_cache[i].chcfg = tmp;
+		mutex_unlock(&mhi_chan->lock);
+	}
+}
+
 static void mhi_ep_release_device(struct device *dev)
 {
 	struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
diff --git a/drivers/bus/mhi/ep/sm.c b/drivers/bus/mhi/ep/sm.c
index 50378b9f7300..0bef5d808195 100644
--- a/drivers/bus/mhi/ep/sm.c
+++ b/drivers/bus/mhi/ep/sm.c
@@ -93,8 +93,11 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl)
 	enum mhi_state old_state;
 	int ret;
 
+	/* If MHI is in M3, resume suspended channels */
 	spin_lock_bh(&mhi_cntrl->state_lock);
 	old_state = mhi_cntrl->mhi_state;
+	if (old_state == MHI_STATE_M3)
+		mhi_ep_resume_channels(mhi_cntrl);
 
 	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
 	if (ret) {
@@ -140,6 +143,7 @@ int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
 	}
 
 	spin_unlock_bh(&mhi_cntrl->state_lock);
+	mhi_ep_suspend_channels(mhi_cntrl);
 
 	/* Signal host that the device moved to M3 */
 	ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_M3);
-- 
2.25.1