bus: mhi: core: Add support for registering MHI client drivers

This commit adds support for registering MHI client drivers with the
MHI stack. MHI client drivers binds to one or more MHI devices inorder
to sends and receive the upper-layer protocol packets like IP packets,
modem control messages, and diagnostics messages over MHI bus.

This is based on the patch submitted by Sujeev Dias:
https://lkml.org/lkml/2018/7/9/987

Signed-off-by: Sujeev Dias <sdias@codeaurora.org>
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
[mani: splitted and cleaned up for upstream]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
Link: https://lore.kernel.org/r/20200220095854.4804-4-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 149 insertions, 0 deletions

diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index 6f24c21284ec..12e386862b3f 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -374,8 +374,157 @@ struct mhi_device *mhi_alloc_device(struct mhi_controller *mhi_cntrl)
 	return mhi_dev;
 }
 
+static int mhi_driver_probe(struct device *dev)
+{
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	struct device_driver *drv = dev->driver;
+	struct mhi_driver *mhi_drv = to_mhi_driver(drv);
+	struct mhi_event *mhi_event;
+	struct mhi_chan *ul_chan = mhi_dev->ul_chan;
+	struct mhi_chan *dl_chan = mhi_dev->dl_chan;
+
+	if (ul_chan) {
+		/*
+		 * If channel supports LPM notifications then status_cb should
+		 * be provided
+		 */
+		if (ul_chan->lpm_notify && !mhi_drv->status_cb)
+			return -EINVAL;
+
+		/* For non-offload channels then xfer_cb should be provided */
+		if (!ul_chan->offload_ch && !mhi_drv->ul_xfer_cb)
+			return -EINVAL;
+
+		ul_chan->xfer_cb = mhi_drv->ul_xfer_cb;
+	}
+
+	if (dl_chan) {
+		/*
+		 * If channel supports LPM notifications then status_cb should
+		 * be provided
+		 */
+		if (dl_chan->lpm_notify && !mhi_drv->status_cb)
+			return -EINVAL;
+
+		/* For non-offload channels then xfer_cb should be provided */
+		if (!dl_chan->offload_ch && !mhi_drv->dl_xfer_cb)
+			return -EINVAL;
+
+		mhi_event = &mhi_cntrl->mhi_event[dl_chan->er_index];
+
+		/*
+		 * If the channel event ring is managed by client, then
+		 * status_cb must be provided so that the framework can
+		 * notify pending data
+		 */
+		if (mhi_event->cl_manage && !mhi_drv->status_cb)
+			return -EINVAL;
+
+		dl_chan->xfer_cb = mhi_drv->dl_xfer_cb;
+	}
+
+	/* Call the user provided probe function */
+	return mhi_drv->probe(mhi_dev, mhi_dev->id);
+}
+
+static int mhi_driver_remove(struct device *dev)
+{
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+	struct mhi_driver *mhi_drv = to_mhi_driver(dev->driver);
+	struct mhi_chan *mhi_chan;
+	enum mhi_ch_state ch_state[] = {
+		MHI_CH_STATE_DISABLED,
+		MHI_CH_STATE_DISABLED
+	};
+	int dir;
+
+	/* Skip if it is a controller device */
+	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
+		return 0;
+
+	/* Reset both channels */
+	for (dir = 0; dir < 2; dir++) {
+		mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;
+
+		if (!mhi_chan)
+			continue;
+
+		/* Wake all threads waiting for completion */
+		write_lock_irq(&mhi_chan->lock);
+		mhi_chan->ccs = MHI_EV_CC_INVALID;
+		complete_all(&mhi_chan->completion);
+		write_unlock_irq(&mhi_chan->lock);
+
+		/* Set the channel state to disabled */
+		mutex_lock(&mhi_chan->mutex);
+		write_lock_irq(&mhi_chan->lock);
+		ch_state[dir] = mhi_chan->ch_state;
+		mhi_chan->ch_state = MHI_CH_STATE_SUSPENDED;
+		write_unlock_irq(&mhi_chan->lock);
+
+		mutex_unlock(&mhi_chan->mutex);
+	}
+
+	mhi_drv->remove(mhi_dev);
+
+	/* De-init channel if it was enabled */
+	for (dir = 0; dir < 2; dir++) {
+		mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;
+
+		if (!mhi_chan)
+			continue;
+
+		mutex_lock(&mhi_chan->mutex);
+
+		mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
+
+		mutex_unlock(&mhi_chan->mutex);
+	}
+
+	return 0;
+}
+
+int mhi_driver_register(struct mhi_driver *mhi_drv)
+{
+	struct device_driver *driver = &mhi_drv->driver;
+
+	if (!mhi_drv->probe || !mhi_drv->remove)
+		return -EINVAL;
+
+	driver->bus = &mhi_bus_type;
+	driver->probe = mhi_driver_probe;
+	driver->remove = mhi_driver_remove;
+
+	return driver_register(driver);
+}
+EXPORT_SYMBOL_GPL(mhi_driver_register);
+
+void mhi_driver_unregister(struct mhi_driver *mhi_drv)
+{
+	driver_unregister(&mhi_drv->driver);
+}
+EXPORT_SYMBOL_GPL(mhi_driver_unregister);
+
 static int mhi_match(struct device *dev, struct device_driver *drv)
 {
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+	struct mhi_driver *mhi_drv = to_mhi_driver(drv);
+	const struct mhi_device_id *id;
+
+	/*
+	 * If the device is a controller type then there is no client driver
+	 * associated with it
+	 */
+	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
+		return 0;
+
+	for (id = mhi_drv->id_table; id->chan[0]; id++)
+		if (!strcmp(mhi_dev->chan_name, id->chan)) {
+			mhi_dev->id = id;
+			return 1;
+		}
+
 	return 0;
 };