misc/mei/hdcp: Client driver for HDCP application

ME FW contributes a vital role in HDCP2.2 authentication.
HDCP2.2 driver needs to communicate to ME FW for each step of the
HDCP2.2 authentication.

ME FW prepare and HDCP2.2 authentication  parameters and encrypt them
as per spec. With such parameter Driver prepares HDCP2.2 auth messages
and communicate with HDCP2.2 sink.

Similarly HDCP2.2 sink's response is shared with ME FW for decrypt and
verification.

Once All the steps of HDCP2.2 authentications are complete on driver's
request ME FW will configure the port as authenticated and supply the
HDCP keys to the Gen HW for encryption.

Only after this stage HDCP2.2 driver can start the HDCP2.2 encryption
for a port.

ME FW is interfaced to kernel through MEI Bus Driver. To obtain the
HDCP2.2 services from the ME FW through MEI Bus driver MEI Client
Driver is developed.

v2:
  hdcp files are moved to drivers/misc/mei/hdcp/ [Tomas]
v3:
  Squashed the Kbuild support [Tomas]
  UUID renamed and Module License is modified [Tomas]
  drv_data is set to null at remove [Tomas]
v4:
  Module name is changed to "MEI HDCP"
  I915 Selects the MEI_HDCP
v5:
  Remove redundant text from the License header
  Fix malformed licence
  Removed the drv_data resetting.
v6:
  K-Doc addition. [Tomas]
v7:
  %s/UUID_LE/GUID_INIT [Tomas]
  GPL Ver is 2.0 than 2.0+ [Tomas]
v8:
  Added more info into Kconfig addition [Tomas]

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1550772730-23280-3-git-send-email-ramalingam.c@intel.com

drivers/misc/mei/Kconfig

@@ -43,3 +43,13 @@ config INTEL_MEI_TXE
 
 	  Supported SoCs:
 	  Intel Bay Trail
+
+config INTEL_MEI_HDCP
+	tristate "Intel HDCP2.2 services of ME Interface"
+	select INTEL_MEI_ME
+	depends on DRM_I915
+	help
+	  MEI Support for HDCP2.2 Services on Intel platforms.
+
+	  Enables the ME FW services required for HDCP2.2 support through
+	  I915 display driver of Intel.

drivers/misc/mei/Makefile

@@ -24,3 +24,5 @@ mei-txe-objs += hw-txe.o
 
 mei-$(CONFIG_EVENT_TRACING) += mei-trace.o
 CFLAGS_mei-trace.o = -I$(src)
+
+obj-$(CONFIG_INTEL_MEI_HDCP) += hdcp/

drivers/misc/mei/hdcp/Makefile

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2019, Intel Corporation.
+#
+# Makefile - HDCP client driver for Intel MEI Bus Driver.
+
+obj-$(CONFIG_INTEL_MEI_HDCP) += mei_hdcp.o

drivers/misc/mei/hdcp/mei_hdcp.c

@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: (GPL-2.0)
+/*
+ * Copyright © 2019 Intel Corporation
+ *
+ * Mei_hdcp.c: HDCP client driver for mei bus
+ *
+ * Author:
+ * Ramalingam C <ramalingam.c@intel.com>
+ */
+
+/**
+ * DOC: MEI_HDCP Client Driver
+ *
+ * This is a client driver to the mei_bus to make the HDCP2.2 services of
+ * ME FW available for the interested consumers like I915.
+ *
+ * This module will act as a translation layer between HDCP protocol
+ * implementor(I915) and ME FW by translating HDCP2.2 authentication
+ * messages to ME FW command payloads and vice versa.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+#include <linux/mei_cl_bus.h>
+
+static int mei_hdcp_probe(struct mei_cl_device *cldev,
+			  const struct mei_cl_device_id *id)
+{
+	int ret;
+
+	ret = mei_cldev_enable(cldev);
+	if (ret < 0)
+		dev_err(&cldev->dev, "mei_cldev_enable Failed. %d\n", ret);
+
+	return ret;
+}
+
+static int mei_hdcp_remove(struct mei_cl_device *cldev)
+{
+	return mei_cldev_disable(cldev);
+}
+
+#define MEI_UUID_HDCP GUID_INIT(0xB638AB7E, 0x94E2, 0x4EA2, 0xA5, \
+				0x52, 0xD1, 0xC5, 0x4B, 0x62, 0x7F, 0x04)
+
+static struct mei_cl_device_id mei_hdcp_tbl[] = {
+	{ .uuid = MEI_UUID_HDCP, .version = MEI_CL_VERSION_ANY },
+	{ }
+};
+MODULE_DEVICE_TABLE(mei, mei_hdcp_tbl);
+
+static struct mei_cl_driver mei_hdcp_driver = {
+	.id_table = mei_hdcp_tbl,
+	.name = KBUILD_MODNAME,
+	.probe = mei_hdcp_probe,
+	.remove	= mei_hdcp_remove,
+};
+
+module_mei_cl_driver(mei_hdcp_driver);
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MEI HDCP");