mei: pxp: add command streamer API to the PXP driver

The discrete graphics card with GSC firmware
using command streamer API hence it requires to enhance
pxp module with the new gsc_command() handler.

The handler is implemented via mei_pxp_gsc_command() which is
just a thin wrapper around mei_cldev_send_gsc_command()
Signed-off-by: Vitaly Lubart <vitaly.lubart@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220928004145.745803-6-daniele.ceraolospurio@intel.com

drivers/misc/mei/pxp/mei_pxp.c

@@ -77,10 +77,35 @@ mei_pxp_receive_message(struct device *dev, void *buffer, size_t size)
 	return byte;
 }
 
+/**
+ * mei_pxp_gsc_command() - sends a gsc command, by sending
+ * a sgl mei message to gsc and receiving reply from gsc
+ *
+ * @dev: device corresponding to the mei_cl_device
+ * @client_id: client id to send the command to
+ * @fence_id: fence id to send the command to
+ * @sg_in: scatter gather list containing addresses for rx message buffer
+ * @total_in_len: total length of data in 'in' sg, can be less than the sum of buffers sizes
+ * @sg_out: scatter gather list containing addresses for tx message buffer
+ *
+ * Return: bytes sent on Success, <0 on Failure
+ */
+static ssize_t mei_pxp_gsc_command(struct device *dev, u8 client_id, u32 fence_id,
+				   struct scatterlist *sg_in, size_t total_in_len,
+				   struct scatterlist *sg_out)
+{
+	struct mei_cl_device *cldev;
+
+	cldev = to_mei_cl_device(dev);
+
+	return mei_cldev_send_gsc_command(cldev, client_id, fence_id, sg_in, total_in_len, sg_out);
+}
+
 static const struct i915_pxp_component_ops mei_pxp_ops = {
 	.owner = THIS_MODULE,
 	.send = mei_pxp_send_message,
 	.recv = mei_pxp_receive_message,
+	.gsc_command = mei_pxp_gsc_command,
 };
 
 static int mei_component_master_bind(struct device *dev)

include/drm/i915_pxp_tee_interface.h

@@ -8,6 +8,7 @@
 
 #include <linux/mutex.h>
 #include <linux/device.h>
+struct scatterlist;
 
 /**
  * struct i915_pxp_component_ops - ops for PXP services.
@@ -23,6 +24,10 @@ struct i915_pxp_component_ops {
 
 	int (*send)(struct device *dev, const void *message, size_t size);
 	int (*recv)(struct device *dev, void *buffer, size_t size);
+	ssize_t (*gsc_command)(struct device *dev, u8 client_id, u32 fence_id,
+			       struct scatterlist *sg_in, size_t total_in_len,
+			       struct scatterlist *sg_out);
+
 };
 
 /**