linux-kernel - [PATCH 16/20] bus: mhi: ep: Add support for handling SYS

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Date:   Thu,  2 Dec 2021 17:05:48 +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 16/20] bus: mhi: ep: Add support for handling SYS_ERR condition

Add support for handling SYS_ERR (System Error) condition in the MHI
endpoint stack. The SYS_ERR flag will be asserted by the endpoint device
when it detects an internal error. The host will then issue reset and
reinitializes MHI to recover from the error state.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/bus/mhi/ep/internal.h |  1 +
 drivers/bus/mhi/ep/main.c     | 24 ++++++++++++++++++++++++
 drivers/bus/mhi/ep/sm.c       |  2 ++
 3 files changed, 27 insertions(+)

diff --git a/drivers/bus/mhi/ep/internal.h b/drivers/bus/mhi/ep/internal.h
index ec508201c5c0..5c6b622482c9 100644
--- a/drivers/bus/mhi/ep/internal.h
+++ b/drivers/bus/mhi/ep/internal.h
@@ -228,5 +228,6 @@ int mhi_ep_set_mhi_state(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state mhi_stat
 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);
 
 #endif
diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index 0b0fad6bf69a..088eac0808d1 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -148,6 +148,30 @@ static int mhi_ep_send_cmd_comp_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_e
 	return mhi_ep_send_event(mhi_cntrl, 0, &event);
 }
 
+/*
+ * We don't need to do anything special other than setting the MHI SYS_ERR
+ * state. The host issue will reset all contexts and issue MHI RESET so that we
+ * could also recover from error state.
+ */
+void mhi_ep_handle_syserr(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	int ret;
+
+	/* If MHI EP is not enabled, nothing to do */
+	if (!mhi_cntrl->is_enabled)
+		return;
+
+	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_SYS_ERR);
+	if (ret)
+		return;
+
+	/* Signal host that the device went to SYS_ERR state */
+	ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_SYS_ERR);
+	if (ret)
+		dev_err(dev, "Failed sending SYS_ERR state change event: %d\n", ret);
+}
+
 static int mhi_ep_cache_host_cfg(struct mhi_ep_cntrl *mhi_cntrl)
 {
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
diff --git a/drivers/bus/mhi/ep/sm.c b/drivers/bus/mhi/ep/sm.c
index 95cec5c627b4..50378b9f7300 100644
--- a/drivers/bus/mhi/ep/sm.c
+++ b/drivers/bus/mhi/ep/sm.c
@@ -98,6 +98,7 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl)
 
 	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
 	if (ret) {
+		mhi_ep_handle_syserr(mhi_cntrl);
 		spin_unlock_bh(&mhi_cntrl->state_lock);
 		return ret;
 	}
@@ -133,6 +134,7 @@ int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
 	spin_lock_bh(&mhi_cntrl->state_lock);
 	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M3);
 	if (ret) {
+		mhi_ep_handle_syserr(mhi_cntrl);
 		spin_unlock_bh(&mhi_cntrl->state_lock);
 		return ret;
 	}
-- 
2.25.1