Merge "mhi: core: add mhi_device_get_sync_atomic() to wait until M0"

drivers/bus/mhi/core/mhi_internal.h

@@ -751,6 +751,8 @@ struct mhi_bus {
 
 /* default MHI timeout */
 #define MHI_TIMEOUT_MS (1000)
+#define MHI_FORCE_WAKE_DELAY_US (100)
+
 extern struct mhi_bus mhi_bus;
 
 struct mhi_controller *find_mhi_controller_by_name(const char *name);

drivers/bus/mhi/core/mhi_pm.c

@@ -405,35 +405,42 @@ void mhi_pm_m1_transition(struct mhi_controller *mhi_cntrl)
 	enum MHI_PM_STATE state;
 
 	write_lock_irq(&mhi_cntrl->pm_lock);
+	/* Just check if we are racing with device_wake assertion */
+	if (atomic_read(&mhi_cntrl->dev_wake))
+		MHI_VERB("M2 transition request post dev_wake:%d\n",
+			 atomic_read(&mhi_cntrl->dev_wake));
+
 	/* if it fails, means we transition to M3 */
 	state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_M2);
-	if (state == MHI_PM_M2) {
-		MHI_VERB("Entered M2 State\n");
-		mhi_set_mhi_state(mhi_cntrl, MHI_STATE_M2);
-		mhi_cntrl->dev_state = MHI_STATE_M2;
-		mhi_cntrl->M2++;
-
-		write_unlock_irq(&mhi_cntrl->pm_lock);
-		wake_up_all(&mhi_cntrl->state_event);
-
-		/* transfer pending, exit M2 immediately */
-		if (unlikely(atomic_read(&mhi_cntrl->pending_pkts) ||
-			     atomic_read(&mhi_cntrl->dev_wake))) {
-			MHI_VERB(
-				 "Exiting M2 Immediately, pending_pkts:%d dev_wake:%d\n",
-				 atomic_read(&mhi_cntrl->pending_pkts),
-				 atomic_read(&mhi_cntrl->dev_wake));
-			read_lock_bh(&mhi_cntrl->pm_lock);
-			mhi_cntrl->wake_get(mhi_cntrl, true);
-			mhi_cntrl->wake_put(mhi_cntrl, true);
-			read_unlock_bh(&mhi_cntrl->pm_lock);
-		} else {
-			mhi_cntrl->status_cb(mhi_cntrl, mhi_cntrl->priv_data,
-					     MHI_CB_IDLE);
-		}
-	} else {
+	if (state != MHI_PM_M2) {
+		/* Nothing to be done, handle M3 transition later */
 		write_unlock_irq(&mhi_cntrl->pm_lock);
+		return;
 	}
+
+	MHI_VERB("Entered M2 State\n");
+	mhi_set_mhi_state(mhi_cntrl, MHI_STATE_M2);
+	mhi_cntrl->dev_state = MHI_STATE_M2;
+	mhi_cntrl->M2++;
+
+	write_unlock_irq(&mhi_cntrl->pm_lock);
+	wake_up_all(&mhi_cntrl->state_event);
+
+	/* transfer pending, exit M2 immediately */
+	if (unlikely(atomic_read(&mhi_cntrl->pending_pkts) ||
+		     atomic_read(&mhi_cntrl->dev_wake))) {
+		MHI_VERB(
+			 "Exiting M2 Immediately, pending_pkts:%d dev_wake:%d\n",
+			 atomic_read(&mhi_cntrl->pending_pkts),
+			 atomic_read(&mhi_cntrl->dev_wake));
+		read_lock_bh(&mhi_cntrl->pm_lock);
+		mhi_cntrl->wake_get(mhi_cntrl, true);
+		mhi_cntrl->wake_put(mhi_cntrl, true);
+		read_unlock_bh(&mhi_cntrl->pm_lock);
+		return;
+	}
+
+	mhi_cntrl->status_cb(mhi_cntrl, mhi_cntrl->priv_data, MHI_CB_IDLE);
 }
 
 int mhi_pm_m3_transition(struct mhi_controller *mhi_cntrl)
@@ -1631,6 +1638,57 @@ int mhi_device_get_sync(struct mhi_device *mhi_dev, int vote)
 }
 EXPORT_SYMBOL(mhi_device_get_sync);
 
+int mhi_device_get_sync_atomic(struct mhi_device *mhi_dev, int timeout_us)
+{
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+
+	read_lock_bh(&mhi_cntrl->pm_lock);
+	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
+		read_unlock_bh(&mhi_cntrl->pm_lock);
+		return -EIO;
+	}
+
+	mhi_cntrl->wake_get(mhi_cntrl, true);
+	read_unlock_bh(&mhi_cntrl->pm_lock);
+
+	atomic_inc(&mhi_dev->dev_vote);
+	pm_wakeup_hard_event(&mhi_cntrl->mhi_dev->dev);
+	mhi_cntrl->runtime_get(mhi_cntrl, mhi_cntrl->priv_data);
+
+	/* Return if client doesn't want us to wait */
+	if (!timeout_us) {
+		if (mhi_cntrl->pm_state != MHI_PM_M0)
+			MHI_ERR("Return without waiting for M0\n");
+
+		mhi_cntrl->runtime_put(mhi_cntrl, mhi_cntrl->priv_data);
+		return 0;
+	}
+
+	while (mhi_cntrl->pm_state != MHI_PM_M0 &&
+			!MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state) &&
+			timeout_us > 0) {
+		udelay(MHI_FORCE_WAKE_DELAY_US);
+		timeout_us -= MHI_FORCE_WAKE_DELAY_US;
+	}
+
+	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state) || timeout_us <= 0) {
+		MHI_ERR("Did not enter M0 state, cur_state:%s pm_state:%s\n",
+			TO_MHI_STATE_STR(mhi_cntrl->dev_state),
+			to_mhi_pm_state_str(mhi_cntrl->pm_state));
+		read_lock_bh(&mhi_cntrl->pm_lock);
+		mhi_cntrl->wake_put(mhi_cntrl, false);
+		read_unlock_bh(&mhi_cntrl->pm_lock);
+		atomic_dec(&mhi_dev->dev_vote);
+		mhi_cntrl->runtime_put(mhi_cntrl, mhi_cntrl->priv_data);
+		return -ETIMEDOUT;
+	}
+
+	mhi_cntrl->runtime_put(mhi_cntrl, mhi_cntrl->priv_data);
+
+	return 0;
+}
+EXPORT_SYMBOL(mhi_device_get_sync_atomic);
+
 void mhi_device_put(struct mhi_device *mhi_dev, int vote)
 {
 	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;

include/linux/mhi.h

@@ -609,6 +609,30 @@ void mhi_device_get(struct mhi_device *mhi_dev, int vote);
  */
 int mhi_device_get_sync(struct mhi_device *mhi_dev, int vote);
 
+/**
+ * mhi_device_get_sync_atomic - Asserts device_wait and moves device to M0
+ * @mhi_dev: Device associated with the channels
+ * @timeout_us: timeout, in micro-seconds
+ *
+ * The device_wake is asserted to keep device in M0 or bring it to M0.
+ * If device is not in M0 state, then this function will wait for device to
+ * move to M0, until @timeout_us elapses.
+ * However, if device's M1 state-change event races with this function
+ * then there is a possiblity of device moving from M0 to M2 and back
+ * to M0. That can't be avoided as host must transition device from M1 to M2
+ * as per the spec.
+ * Clients can ignore that transition after this function returns as the device
+ * is expected to immediately  move from M2 to M0 as wake is asserted and
+ * wouldn't enter low power state.
+ *
+ * Returns:
+ * 0 if operation was successful (however, M0 -> M2 -> M0 is possible later) as
+ * mentioned above.
+ * -ETIMEDOUT is device faled to move to M0 before @timeout_us elapsed
+ * -EIO if the MHI state is one of the ERROR states.
+ */
+int mhi_device_get_sync_atomic(struct mhi_device *mhi_dev, int timeout_us);
+
 /**
  * mhi_device_put - re-enable low power modes
  * @mhi_dev: Device associated with the channels