mei: bus: add client dma interface

Expose the client dma mapping via mei client bus interface.
The client dma has to be mapped before the device is enabled,
therefore we need to create device linking already during mapping
and we need to unmap after the client is disable hence we need to
postpone the unlink and flush till unmapping or when
destroying the device.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Co-developed-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20210420172755.12178-1-emmanuel.grumbach@intel.com
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211112062814.7502-1-emmanuel.grumbach@intel.com

drivers/misc/mei/bus.c

@@ -643,6 +643,64 @@ static void mei_cl_bus_vtag_free(struct mei_cl_device *cldev)
 	kfree(cl_vtag);
 }
 
+void *mei_cldev_dma_map(struct mei_cl_device *cldev, u8 buffer_id, size_t size)
+{
+	struct mei_device *bus;
+	struct mei_cl *cl;
+	int ret;
+
+	if (!cldev || !buffer_id || !size)
+		return ERR_PTR(-EINVAL);
+
+	if (!IS_ALIGNED(size, MEI_FW_PAGE_SIZE)) {
+		dev_err(&cldev->dev, "Map size should be aligned to %lu\n",
+			MEI_FW_PAGE_SIZE);
+		return ERR_PTR(-EINVAL);
+	}
+
+	cl = cldev->cl;
+	bus = cldev->bus;
+
+	mutex_lock(&bus->device_lock);
+	if (cl->state == MEI_FILE_UNINITIALIZED) {
+		ret = mei_cl_link(cl);
+		if (ret)
+			goto out;
+		/* update pointers */
+		cl->cldev = cldev;
+	}
+
+	ret = mei_cl_dma_alloc_and_map(cl, NULL, buffer_id, size);
+out:
+	mutex_unlock(&bus->device_lock);
+	if (ret)
+		return ERR_PTR(ret);
+	return cl->dma.vaddr;
+}
+EXPORT_SYMBOL_GPL(mei_cldev_dma_map);
+
+int mei_cldev_dma_unmap(struct mei_cl_device *cldev)
+{
+	struct mei_device *bus;
+	struct mei_cl *cl;
+	int ret;
+
+	if (!cldev)
+		return -EINVAL;
+
+	cl = cldev->cl;
+	bus = cldev->bus;
+
+	mutex_lock(&bus->device_lock);
+	ret = mei_cl_dma_unmap(cl, NULL);
+
+	mei_cl_flush_queues(cl, NULL);
+	mei_cl_unlink(cl);
+	mutex_unlock(&bus->device_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mei_cldev_dma_unmap);
+
 /**
  * mei_cldev_enable - enable me client device
  *     create connection with me client
@@ -753,9 +811,11 @@ int mei_cldev_disable(struct mei_cl_device *cldev)
 		dev_err(bus->dev, "Could not disconnect from the ME client\n");
 
 out:
-	/* Flush queues and remove any pending read */
-	mei_cl_flush_queues(cl, NULL);
-	mei_cl_unlink(cl);
+	/* Flush queues and remove any pending read unless we have mapped DMA */
+	if (!cl->dma_mapped) {
+		mei_cl_flush_queues(cl, NULL);
+		mei_cl_unlink(cl);
+	}
 
 	mutex_unlock(&bus->device_lock);
 	return err;
@@ -1052,6 +1112,7 @@ static void mei_cl_bus_dev_release(struct device *dev)
 	if (!cldev)
 		return;
 
+	mei_cl_flush_queues(cldev->cl, NULL);
 	mei_me_cl_put(cldev->me_cl);
 	mei_dev_bus_put(cldev->bus);
 	mei_cl_unlink(cldev->cl);

drivers/misc/mei/client.c

@@ -700,6 +700,9 @@ int mei_cl_unlink(struct mei_cl *cl)
 
 	cl_dbg(dev, cl, "unlink client");
 
+	if (cl->state == MEI_FILE_UNINITIALIZED)
+		return 0;
+
 	if (dev->open_handle_count > 0)
 		dev->open_handle_count--;
 

drivers/misc/mei/hw.h

@@ -22,6 +22,11 @@
 #define MEI_D0I3_TIMEOUT            5  /* D0i3 set/unset max response time */
 #define MEI_HBM_TIMEOUT             1  /* 1 second */
 
+/*
+ * FW page size for DMA allocations
+ */
+#define MEI_FW_PAGE_SIZE 4096UL
+
 /*
  * MEI Version
  */

include/linux/mei_cl_bus.h

@@ -117,4 +117,7 @@ int mei_cldev_enable(struct mei_cl_device *cldev);
 int mei_cldev_disable(struct mei_cl_device *cldev);
 bool mei_cldev_enabled(const struct mei_cl_device *cldev);
 
+void *mei_cldev_dma_map(struct mei_cl_device *cldev, u8 buffer_id, size_t size);
+int mei_cldev_dma_unmap(struct mei_cl_device *cldev);
+
 #endif /* _LINUX_MEI_CL_BUS_H */