[v2,1/3] bus: mhi: core: Add support for MHI suspend and resume

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index eb4256b81406..3e9aa3b2da77 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -267,7 +267,7 @@  int mhi_destroy_device(struct device *dev, void *data)
 	return 0;
 }
 
-static void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason)
+void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason)
 {
 	struct mhi_driver *mhi_drv;
 
@@ -279,6 +279,7 @@  static void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason)
 	if (mhi_drv->status_cb)
 		mhi_drv->status_cb(mhi_dev, cb_reason);
 }
+EXPORT_SYMBOL_GPL(mhi_notify);
 
 /* Bind MHI channels to MHI devices */
 void mhi_create_devices(struct mhi_controller *mhi_cntrl)
diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index 52690cb5c89c..3529419d076b 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -669,6 +669,149 @@  void mhi_pm_st_worker(struct work_struct *work)
 	}
 }
 
+int mhi_pm_suspend(struct mhi_controller *mhi_cntrl)
+{
+	struct mhi_chan *itr, *tmp;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	enum mhi_pm_state new_state;
+	int ret;
+
+	if (mhi_cntrl->pm_state == MHI_PM_DISABLE)
+		return -EINVAL;
+
+	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state))
+		return -EIO;
+
+	/* Return busy if there are any pending resources */
+	if (atomic_read(&mhi_cntrl->dev_wake))
+		return -EBUSY;
+
+	/* Take MHI out of M2 state */
+	read_lock_bh(&mhi_cntrl->pm_lock);
+	mhi_cntrl->wake_get(mhi_cntrl, false);
+	read_unlock_bh(&mhi_cntrl->pm_lock);
+
+	ret = wait_event_timeout(mhi_cntrl->state_event,
+				 mhi_cntrl->dev_state == MHI_STATE_M0 ||
+				 mhi_cntrl->dev_state == MHI_STATE_M1 ||
+				 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
+				 msecs_to_jiffies(mhi_cntrl->timeout_ms));
+
+	read_lock_bh(&mhi_cntrl->pm_lock);
+	mhi_cntrl->wake_put(mhi_cntrl, false);
+	read_unlock_bh(&mhi_cntrl->pm_lock);
+
+	if (!ret || MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
+		dev_err(dev,
+			"Could not enter M0/M1 state");
+		return -EIO;
+	}
+
+	write_lock_irq(&mhi_cntrl->pm_lock);
+
+	if (atomic_read(&mhi_cntrl->dev_wake)) {
+		write_unlock_irq(&mhi_cntrl->pm_lock);
+		return -EBUSY;
+	}
+
+	dev_info(dev, "Allowing M3 transition\n");
+	new_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_M3_ENTER);
+	if (new_state != MHI_PM_M3_ENTER) {
+		write_unlock_irq(&mhi_cntrl->pm_lock);
+		dev_err(dev,
+			"Error setting to PM state: %s from: %s\n",
+			to_mhi_pm_state_str(MHI_PM_M3_ENTER),
+			to_mhi_pm_state_str(mhi_cntrl->pm_state));
+		return -EIO;
+	}
+
+	/* Set MHI to M3 and wait for completion */
+	mhi_set_mhi_state(mhi_cntrl, MHI_STATE_M3);
+	write_unlock_irq(&mhi_cntrl->pm_lock);
+	dev_info(dev, "Wait for M3 completion\n");
+
+	ret = wait_event_timeout(mhi_cntrl->state_event,
+				 mhi_cntrl->dev_state == MHI_STATE_M3 ||
+				 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
+				 msecs_to_jiffies(mhi_cntrl->timeout_ms));
+
+	if (!ret || MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
+		dev_err(dev,
+			"Did not enter M3 state, MHI state: %s, PM state: %s\n",
+			TO_MHI_STATE_STR(mhi_cntrl->dev_state),
+			to_mhi_pm_state_str(mhi_cntrl->pm_state));
+		return -EIO;
+	}
+
+	/* Notify clients about entering LPM */
+	list_for_each_entry_safe(itr, tmp, &mhi_cntrl->lpm_chans, node) {
+		mutex_lock(&itr->mutex);
+		if (itr->mhi_dev)
+			mhi_notify(itr->mhi_dev, MHI_CB_LPM_ENTER);
+		mutex_unlock(&itr->mutex);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mhi_pm_suspend);
+
+int mhi_pm_resume(struct mhi_controller *mhi_cntrl)
+{
+	struct mhi_chan *itr, *tmp;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	enum mhi_pm_state cur_state;
+	int ret;
+
+	dev_info(dev, "Entered with PM state: %s, MHI state: %s\n",
+		 to_mhi_pm_state_str(mhi_cntrl->pm_state),
+		 TO_MHI_STATE_STR(mhi_cntrl->dev_state));
+
+	if (mhi_cntrl->pm_state == MHI_PM_DISABLE)
+		return 0;
+
+	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state))
+		return -EIO;
+
+	/* Notify clients about exiting LPM */
+	list_for_each_entry_safe(itr, tmp, &mhi_cntrl->lpm_chans, node) {
+		mutex_lock(&itr->mutex);
+		if (itr->mhi_dev)
+			mhi_notify(itr->mhi_dev, MHI_CB_LPM_EXIT);
+		mutex_unlock(&itr->mutex);
+	}
+
+	write_lock_irq(&mhi_cntrl->pm_lock);
+	cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_M3_EXIT);
+	if (cur_state != MHI_PM_M3_EXIT) {
+		write_unlock_irq(&mhi_cntrl->pm_lock);
+		dev_info(dev,
+			 "Error setting to PM state: %s from: %s\n",
+			 to_mhi_pm_state_str(MHI_PM_M3_EXIT),
+			 to_mhi_pm_state_str(mhi_cntrl->pm_state));
+		return -EIO;
+	}
+
+	/* Set MHI to M0 and wait for completion */
+	mhi_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
+	write_unlock_irq(&mhi_cntrl->pm_lock);
+
+	ret = wait_event_timeout(mhi_cntrl->state_event,
+				 mhi_cntrl->dev_state == MHI_STATE_M0 ||
+				 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
+				 msecs_to_jiffies(mhi_cntrl->timeout_ms));
+
+	if (!ret || MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
+		dev_err(dev,
+			"Did not enter M0 state, MHI state: %s, PM state: %s\n",
+			TO_MHI_STATE_STR(mhi_cntrl->dev_state),
+			to_mhi_pm_state_str(mhi_cntrl->pm_state));
+		return -EIO;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mhi_pm_resume);
+
 int __mhi_device_get_sync(struct mhi_controller *mhi_cntrl)
 {
 	int ret;
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index ad1996001965..a4288f4d656f 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -568,6 +568,13 @@  void mhi_driver_unregister(struct mhi_driver *mhi_drv);
 void mhi_set_mhi_state(struct mhi_controller *mhi_cntrl,
 		       enum mhi_state state);
 
+/**
+ * mhi_notify - Notify the MHI client driver about client device status
+ * @mhi_dev: MHI device instance
+ * @cb_reason: MHI callback reason
+ */
+void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason);
+
 /**
  * mhi_prepare_for_power_up - Do pre-initialization before power up.
  *                            This is optional, call this before power up if
@@ -604,6 +611,18 @@  void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful);
  */
 void mhi_unprepare_after_power_down(struct mhi_controller *mhi_cntrl);
 
+/**
+ * mhi_pm_suspend - Move MHI into a suspended state
+ * @mhi_cntrl: MHI controller
+ */
+int mhi_pm_suspend(struct mhi_controller *mhi_cntrl);
+
+/**
+ * mhi_pm_resume - Resume MHI from suspended state
+ * @mhi_cntrl: MHI controller
+ */
+int mhi_pm_resume(struct mhi_controller *mhi_cntrl);
+
 /**
  * mhi_download_rddm_img - Download ramdump image from device for
  *                         debugging purpose.