bus: mhi: ep: Add support for registering MHI endpoint client drivers

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

Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220405135754.6622-3-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 85 insertions, 0 deletions

diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index d932ad01761b..f7d5f75fc083 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -198,9 +198,88 @@ void mhi_ep_unregister_controller(struct mhi_ep_cntrl *mhi_cntrl)
 }
 EXPORT_SYMBOL_GPL(mhi_ep_unregister_controller);
 
+static int mhi_ep_driver_probe(struct device *dev)
+{
+	struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
+	struct mhi_ep_driver *mhi_drv = to_mhi_ep_driver(dev->driver);
+	struct mhi_ep_chan *ul_chan = mhi_dev->ul_chan;
+	struct mhi_ep_chan *dl_chan = mhi_dev->dl_chan;
+
+	ul_chan->xfer_cb = mhi_drv->ul_xfer_cb;
+	dl_chan->xfer_cb = mhi_drv->dl_xfer_cb;
+
+	return mhi_drv->probe(mhi_dev, mhi_dev->id);
+}
+
+static int mhi_ep_driver_remove(struct device *dev)
+{
+	struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
+	struct mhi_ep_driver *mhi_drv = to_mhi_ep_driver(dev->driver);
+	struct mhi_result result = {};
+	struct mhi_ep_chan *mhi_chan;
+	int dir;
+
+	/* Skip if it is a controller device */
+	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
+		return 0;
+
+	/* Disconnect the channels associated with the driver */
+	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->lock);
+		/* Send channel disconnect status to the client driver */
+		if (mhi_chan->xfer_cb) {
+			result.transaction_status = -ENOTCONN;
+			result.bytes_xferd = 0;
+			mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
+		}
+
+		mhi_chan->state = MHI_CH_STATE_DISABLED;
+		mhi_chan->xfer_cb = NULL;
+		mutex_unlock(&mhi_chan->lock);
+	}
+
+	/* Remove the client driver now */
+	mhi_drv->remove(mhi_dev);
+
+	return 0;
+}
+
+int __mhi_ep_driver_register(struct mhi_ep_driver *mhi_drv, struct module *owner)
+{
+	struct device_driver *driver = &mhi_drv->driver;
+
+	if (!mhi_drv->probe || !mhi_drv->remove)
+		return -EINVAL;
+
+	/* Client drivers should have callbacks defined for both channels */
+	if (!mhi_drv->ul_xfer_cb || !mhi_drv->dl_xfer_cb)
+		return -EINVAL;
+
+	driver->bus = &mhi_ep_bus_type;
+	driver->owner = owner;
+	driver->probe = mhi_ep_driver_probe;
+	driver->remove = mhi_ep_driver_remove;
+
+	return driver_register(driver);
+}
+EXPORT_SYMBOL_GPL(__mhi_ep_driver_register);
+
+void mhi_ep_driver_unregister(struct mhi_ep_driver *mhi_drv)
+{
+	driver_unregister(&mhi_drv->driver);
+}
+EXPORT_SYMBOL_GPL(mhi_ep_driver_unregister);
+
 static int mhi_ep_match(struct device *dev, struct device_driver *drv)
 {
 	struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
+	struct mhi_ep_driver *mhi_drv = to_mhi_ep_driver(drv);
+	const struct mhi_device_id *id;
 
 	/*
 	 * If the device is a controller type then there is no client driver
@@ -209,6 +288,12 @@ static int mhi_ep_match(struct device *dev, struct device_driver *drv)
 	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
 		return 0;
 
+	for (id = mhi_drv->id_table; id->chan[0]; id++)
+		if (!strcmp(mhi_dev->name, id->chan)) {
+			mhi_dev->id = id;
+			return 1;
+		}
+
 	return 0;
 };