media: docs: split ci.rst into uAPI and user guide docs

The ci.rst file contains two parts: the first one describing
how to use the CA high level interface; the second one with
uAPI internals.

Split this on two separate files, adding the uAPI bits
to the DVB ca.rst configuration.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

2 files changed, 158 insertions, 0 deletions

diff --git a/Documentation/media/uapi/dvb/ca.rst b/Documentation/media/uapi/dvb/ca.rst
index 8796512c1378..c6ee624b1234 100644
--- a/Documentation/media/uapi/dvb/ca.rst
+++ b/Documentation/media/uapi/dvb/ca.rst
@@ -29,3 +29,4 @@ application.
 
     ca_data_types
     ca_function_calls
+    ca_high_level
diff --git a/Documentation/media/uapi/dvb/ca_high_level.rst b/Documentation/media/uapi/dvb/ca_high_level.rst
new file mode 100644
index 000000000000..a73f3691c31f
--- /dev/null
+++ b/Documentation/media/uapi/dvb/ca_high_level.rst
@@ -0,0 +1,157 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The High level CI API
+=====================
+
+.. note::
+
+   This documentation is outdated.
+
+This document describes the high level CI API as in accordance to the
+Linux DVB API.
+
+
+With the High Level CI approach any new card with almost any random
+architecture can be implemented with this style, the definitions
+inside the switch statement can be easily adapted for any card, thereby
+eliminating the need for any additional ioctls.
+
+The disadvantage is that the driver/hardware has to manage the rest. For
+the application programmer it would be as simple as sending/receiving an
+array to/from the CI ioctls as defined in the Linux DVB API. No changes
+have been made in the API to accommodate this feature.
+
+
+Why the need for another CI interface?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This is one of the most commonly asked question. Well a nice question.
+Strictly speaking this is not a new interface.
+
+The CI interface is defined in the DVB API in ca.h as:
+
+.. code-block:: c
+
+	typedef struct ca_slot_info {
+		int num;               /* slot number */
+
+		int type;              /* CA interface this slot supports */
+	#define CA_CI            1     /* CI high level interface */
+	#define CA_CI_LINK       2     /* CI link layer level interface */
+	#define CA_CI_PHYS       4     /* CI physical layer level interface */
+	#define CA_DESCR         8     /* built-in descrambler */
+	#define CA_SC          128     /* simple smart card interface */
+
+		unsigned int flags;
+	#define CA_CI_MODULE_PRESENT 1 /* module (or card) inserted */
+	#define CA_CI_MODULE_READY   2
+	} ca_slot_info_t;
+
+This CI interface follows the CI high level interface, which is not
+implemented by most applications. Hence this area is revisited.
+
+This CI interface is quite different in the case that it tries to
+accommodate all other CI based devices, that fall into the other categories.
+
+This means that this CI interface handles the EN50221 style tags in the
+Application layer only and no session management is taken care of by the
+application. The driver/hardware will take care of all that.
+
+This interface is purely an EN50221 interface exchanging APDU's. This
+means that no session management, link layer or a transport layer do
+exist in this case in the application to driver communication. It is
+as simple as that. The driver/hardware has to take care of that.
+
+With this High Level CI interface, the interface can be defined with the
+regular ioctls.
+
+All these ioctls are also valid for the High level CI interface
+
+#define CA_RESET          _IO('o', 128)
+#define CA_GET_CAP        _IOR('o', 129, ca_caps_t)
+#define CA_GET_SLOT_INFO  _IOR('o', 130, ca_slot_info_t)
+#define CA_GET_DESCR_INFO _IOR('o', 131, ca_descr_info_t)
+#define CA_GET_MSG        _IOR('o', 132, ca_msg_t)
+#define CA_SEND_MSG       _IOW('o', 133, ca_msg_t)
+#define CA_SET_DESCR      _IOW('o', 134, ca_descr_t)
+
+
+On querying the device, the device yields information thus:
+
+.. code-block:: none
+
+	CA_GET_SLOT_INFO
+	----------------------------
+	Command = [info]
+	APP: Number=[1]
+	APP: Type=[1]
+	APP: flags=[1]
+	APP: CI High level interface
+	APP: CA/CI Module Present
+
+	CA_GET_CAP
+	----------------------------
+	Command = [caps]
+	APP: Slots=[1]
+	APP: Type=[1]
+	APP: Descrambler keys=[16]
+	APP: Type=[1]
+
+	CA_SEND_MSG
+	----------------------------
+	Descriptors(Program Level)=[ 09 06 06 04 05 50 ff f1]
+	Found CA descriptor @ program level
+
+	(20) ES type=[2] ES pid=[201]  ES length =[0 (0x0)]
+	(25) ES type=[4] ES pid=[301]  ES length =[0 (0x0)]
+	ca_message length is 25 (0x19) bytes
+	EN50221 CA MSG=[ 9f 80 32 19 03 01 2d d1 f0 08 01 09 06 06 04 05 50 ff f1 02 e0 c9 00 00 04 e1 2d 00 00]
+
+
+Not all ioctl's are implemented in the driver from the API, the other
+features of the hardware that cannot be implemented by the API are achieved
+using the CA_GET_MSG and CA_SEND_MSG ioctls. An EN50221 style wrapper is
+used to exchange the data to maintain compatibility with other hardware.
+
+.. code-block:: c
+
+	/* a message to/from a CI-CAM */
+	typedef struct ca_msg {
+		unsigned int index;
+		unsigned int type;
+		unsigned int length;
+		unsigned char msg[256];
+	} ca_msg_t;
+
+
+The flow of data can be described thus,
+
+.. code-block:: none
+
+	App (User)
+	-----
+	parse
+	  |
+	  |
+	  v
+	en50221 APDU (package)
+   --------------------------------------
+   |	  |				| High Level CI driver
+   |	  |				|
+   |	  v				|
+   |	en50221 APDU (unpackage)	|
+   |	  |				|
+   |	  |				|
+   |	  v				|
+   |	sanity checks			|
+   |	  |				|
+   |	  |				|
+   |	  v				|
+   |	do (H/W dep)			|
+   --------------------------------------
+	  |    Hardware
+	  |
+	  v
+
+The High Level CI interface uses the EN50221 DVB standard, following a
+standard ensures futureproofness.