1 .. SPDX-License-Identifier: GPL-2.0
2
3 The High level CI API
4 =====================
5
6 .. note::
7
8 This documentation is outdated.
9
10 This document describes the high level CI API as in accordance to the
11 Linux DVB API.
12
13
14 With the High Level CI approach any new card with almost any random
15 architecture can be implemented with this style, the definitions
16 inside the switch statement can be easily adapted for any card, thereby
17 eliminating the need for any additional ioctls.
18
19 The disadvantage is that the driver/hardware has to manage the rest. For
20 the application programmer it would be as simple as sending/receiving an
21 array to/from the CI ioctls as defined in the Linux DVB API. No changes
22 have been made in the API to accommodate this feature.
23
24
25 Why the need for another CI interface?
26 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
27
28 This is one of the most commonly asked question. Well a nice question.
29 Strictly speaking this is not a new interface.
30
31 The CI interface is defined in the DVB API in ca.h as:
32
33 .. code-block:: c
34
35 typedef struct ca_slot_info {
36 int num; /* slot number */
37
38 int type; /* CA interface this slot supports */
39 #define CA_CI 1 /* CI high level interface */
40 #define CA_CI_LINK 2 /* CI link layer level interface */
41 #define CA_CI_PHYS 4 /* CI physical layer level interface */
42 #define CA_DESCR 8 /* built-in descrambler */
43 #define CA_SC 128 /* simple smart card interface */
44
45 unsigned int flags;
46 #define CA_CI_MODULE_PRESENT 1 /* module (or card) inserted */
47 #define CA_CI_MODULE_READY 2
48 } ca_slot_info_t;
49
50 This CI interface follows the CI high level interface, which is not
51 implemented by most applications. Hence this area is revisited.
52
53 This CI interface is quite different in the case that it tries to
54 accommodate all other CI based devices, that fall into the other categories.
55
56 This means that this CI interface handles the EN50221 style tags in the
57 Application layer only and no session management is taken care of by the
58 application. The driver/hardware will take care of all that.
59
60 This interface is purely an EN50221 interface exchanging APDU's. This
61 means that no session management, link layer or a transport layer do
62 exist in this case in the application to driver communication. It is
63 as simple as that. The driver/hardware has to take care of that.
64
65 With this High Level CI interface, the interface can be defined with the
66 regular ioctls.
67
68 All these ioctls are also valid for the High level CI interface
69
70 #define CA_RESET _IO('o', 128)
71 #define CA_GET_CAP _IOR('o', 129, ca_caps_t)
72 #define CA_GET_SLOT_INFO _IOR('o', 130, ca_slot_info_t)
73 #define CA_GET_DESCR_INFO _IOR('o', 131, ca_descr_info_t)
74 #define CA_GET_MSG _IOR('o', 132, ca_msg_t)
75 #define CA_SEND_MSG _IOW('o', 133, ca_msg_t)
76 #define CA_SET_DESCR _IOW('o', 134, ca_descr_t)
77
78
79 On querying the device, the device yields information thus:
80
81 .. code-block:: none
82
83 CA_GET_SLOT_INFO
84 ----------------------------
85 Command = [info]
86 APP: Number=[1]
87 APP: Type=[1]
88 APP: flags=[1]
89 APP: CI High level interface
90 APP: CA/CI Module Present
91
92 CA_GET_CAP
93 ----------------------------
94 Command = [caps]
95 APP: Slots=[1]
96 APP: Type=[1]
97 APP: Descrambler keys=[16]
98 APP: Type=[1]
99
100 CA_SEND_MSG
101 ----------------------------
102 Descriptors(Program Level)=[ 09 06 06 04 05 50 ff f1]
103 Found CA descriptor @ program level
104
105 (20) ES type=[2] ES pid=[201] ES length =[0 (0x0)]
106 (25) ES type=[4] ES pid=[301] ES length =[0 (0x0)]
107 ca_message length is 25 (0x19) bytes
108 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]
109
110
111 Not all ioctl's are implemented in the driver from the API, the other
112 features of the hardware that cannot be implemented by the API are achieved
113 using the CA_GET_MSG and CA_SEND_MSG ioctls. An EN50221 style wrapper is
114 used to exchange the data to maintain compatibility with other hardware.
115
116 .. code-block:: c
117
118 /* a message to/from a CI-CAM */
119 typedef struct ca_msg {
120 unsigned int index;
121 unsigned int type;
122 unsigned int length;
123 unsigned char msg[256];
124 } ca_msg_t;
125
126
127 The flow of data can be described thus,
128
129 .. code-block:: none
130
131 App (User)
132 -----
133 parse
134 |
135 |
136 v
137 en50221 APDU (package)
138 --------------------------------------
139 | | | High Level CI driver
140 | | |
141 | v |
142 | en50221 APDU (unpackage) |
143 | | |
144 | | |
145 | v |
146 | sanity checks |
147 | | |
148 | | |
149 | v |
150 | do (H/W dep) |
151 --------------------------------------
152 | Hardware
153 |
154 v
155
156 The High Level CI interface uses the EN50221 DVB standard, following a
157 standard ensures futureproofness.
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