1 ============
2 Introduction
3 ============
4
5 The RapidIO standard is a packet-based fabric
6 use in embedded systems. Development of the Ra
7 RapidIO Trade Association (RTA). The current v
8 is publicly available for download from the RT
9
10 This document describes the basics of the Linu
11 information on its major components.
12
13 1 Overview
14 ==========
15
16 Because the RapidIO subsystem follows the Linu
17 into the kernel similarly to other buses by de
18 bus types and registering them within the devi
19
20 The Linux RapidIO subsystem is architecture in
21 architecture-specific interfaces that provide
22 subsystem operations.
23
24 2. Core Components
25 ==================
26
27 A typical RapidIO network is a combination of
28 Each of these components is represented in the
29 structure. The core logical components of the
30 in include/linux/rio.h file.
31
32 2.1 Master Port
33 ---------------
34
35 A master port (or mport) is a RapidIO interfac
36 processor executing the Linux code. A master p
37 packets (transactions). In the RapidIO subsyst
38 by a rio_mport data structure. This structure
39 resources such as mailboxes and doorbells. The
40 host device ID that is valid when a master por
41 host.
42
43 RapidIO master ports are serviced by subsystem
44 that provide functionality defined for this su
45 independent interface for RapidIO subsystem op
46 includes rio_ops data structure which contains
47 implementations of RapidIO functions.
48
49 2.2 Device
50 ----------
51
52 A RapidIO device is any endpoint (other than m
53 All devices are presented in the RapidIO subsy
54 structure. Devices form one global device list
55 (depending on number of available mports and n
56
57 2.3 Switch
58 ----------
59
60 A RapidIO switch is a special class of device
61 ports towards their final destination. The pac
62 switch is defined by an internal routing table
63 RapidIO subsystem by rio_dev data structure ex
64 data structure, which contains switch specific
65 routing table and pointers to switch specific
66
67 The RapidIO subsystem defines the format and i
68 specific switch drivers that are designed to p
69 implementation of common switch management rou
70
71 2.4 Network
72 -----------
73
74 A RapidIO network is a combination of intercon
75 Each RapidIO network known to the system is re
76 data structure. This structure includes lists
77 ports that form the same network. It also cont
78 master port that is used to communicate with d
79
80 2.5 Device Drivers
81 ------------------
82
83 RapidIO device-specific drivers follow Linux K
84 intended to support specific RapidIO devices a
85
86 2.6 Subsystem Interfaces
87 ------------------------
88
89 RapidIO interconnect specification defines fea
90 one or more common service layers for all part
91 common services may act separately from device
92 device-specific drivers. Example of such servi
93 which implements Ethernet-over-RapidIO interfa
94 registered for a device, all common RapidIO se
95 subsystem interfaces. This allows to have mult
96 the same device without blocking attachment of
97
98 3. Subsystem Initialization
99 ===========================
100
101 In order to initialize the RapidIO subsystem,
102 register at least one master port within the R
103 within the subsystem controller driver's initi
104 rio_register_mport() for each available master
105
106 After all active master ports are registered w
107 an enumeration and/or discovery routine may be
108 by user-space command.
109
110 RapidIO subsystem can be configured to be buil
111 modular component of the kernel (see details b
112
113 4. Enumeration and Discovery
114 ============================
115
116 4.1 Overview
117 ------------
118
119 RapidIO subsystem configuration options allow
120 discovery methods as statically linked compone
121 An enumeration/discovery method implementation
122 define how any given method can be attached to
123 simply to all available mports OR individually
124
125 Depending on selected enumeration/discovery bu
126 several methods to initiate an enumeration and
127
128 (a) Statically linked enumeration and discov
129 automatically during kernel initialization t
130 parameters. This was the original method use
131 subsystem. Now this method relies on enumera
132 'rio-scan.scan' for existing basic enumerati
133 When automatic start of enumeration/discover
134 that all discovering endpoints are started b
135 and are waiting for enumeration to be comple
136 Configuration option CONFIG_RAPIDIO_DISC_TIM
137 endpoint waits for enumeration to be complet
138 expires the discovery process is terminated
139 information. NOTE: a timed out discovery pro
140 a user-space command as it is described belo
141 enumerated successfully).
142
143 (b) Statically linked enumeration and discov
144 a command from user space. This initiation m
145 for a system startup compared to the option
146 endpoints have been successfully booted, an
147 started first by issuing a user-space comman
148 completed a discovery process can be started
149
150 (c) Modular enumeration and discovery proces
151 user space. After an enumeration/discovery m
152 process can be started by issuing a user-spa
153 Similar to the option (b) above, an enumerat
154
155 (d) Modular enumeration and discovery proces
156 initialization routine. In this case an enum
157 first.
158
159 When a network scan process is started it call
160 routine depending on the configured role of a
161
162 Enumeration is performed by a master port if i
163 assigning a host destination ID greater than o
164 destination ID can be assigned to a master por
165 on RapidIO subsystem build configuration:
166
167 (a) For a statically linked RapidIO subsyste
168 "rapidio.hdid=" with a list of destination I
169 device registration. For example, in a syste
170 the command line parameter "rapidio.hdid=-1,
171 the host destination ID=7 to the second Rapi
172 one will be assigned destination ID=-1.
173
174 (b) If the RapidIO subsystem core is built a
175 to the method shown above, the host destinat
176 traditional methods of passing module parame
177
178 - from command line: "modprobe rapidio hdid=
179 - from modprobe configuration file using con
180 like in this example: "options rapidio hdi
181 configuration file is provided in the sect
182
183 NOTES:
184 (i) if "hdid=" parameter is omitted all avai
185 destination ID = -1;
186
187 (ii) the "hdid=" parameter in systems with m
188 destination ID assignments omitted from the
189
190 If the host device ID for a specific master po
191 process will be performed for it.
192
193 The enumeration and discovery routines use Rap
194 to access the configuration space of devices.
195
196 NOTE: If RapidIO switch-specific device driver
197 they must be loaded before enumeration/discove
198 This requirement is cased by the fact that enu
199 vendor-specific callbacks on early stages.
200
201 4.2 Automatic Start of Enumeration and Discove
202 ----------------------------------------------
203
204 Automatic enumeration/discovery start method i
205 enumeration/discovery RapidIO configuration se
206 enumeration/discovery start by existing basic
207 command line parameter "rio-scan.scan=1".
208
209 This configuration requires synchronized start
210 form a network which will be enumerated/discov
211 to be started before an enumeration starts to
212 controllers have been initialized and are read
213 parameter CONFIG_RAPIDIO_DISC_TIMEOUT defines
214 a discovering endpoint will wait for enumerati
215
216 When automatic enumeration/discovery start is
217 initialization routine calls rio_init_mports()
218 discovery for all known mport devices.
219
220 Depending on RapidIO network size and configur
221 enumeration/discovery start method may be diff
222 requirement for synchronized start of all endp
223
224 4.3 User-space Start of Enumeration and Discov
225 ----------------------------------------------
226
227 User-space start of enumeration and discovery
228 modular build configurations. For user-space c
229 creates the sysfs write-only attribute file '/
230 an enumeration or discovery process on specifi
231 write mport_ID (not RapidIO destination ID) in
232 sequential number (0 ... RIO_MAX_MPORTS) assig
233 registration. For example for machine with sin
234 for that controller always will be 0.
235
236 To initiate RapidIO enumeration/discovery on a
237 write '-1' (or RIO_MPORT_ANY) into the scan at
238
239 4.4 Basic Enumeration Method
240 ----------------------------
241
242 This is an original enumeration/discovery meth
243 first release of RapidIO subsystem code. The e
244 implemented according to the enumeration algor
245 Interconnect Specification: Annex I [1].
246
247 This method can be configured as statically li
248 The method's single parameter "scan" allows to
249 process from module initialization routine.
250
251 This enumeration/discovery method can be start
252 unloading if it is built as a module.
253
254 The enumeration process traverses the network
255 algorithm. When a new device is found, the enu
256 device by writing into the Host Device ID Lock
257 the enumerator has exclusive right to enumerat
258 is successfully acquired, the enumerator alloc
259 initializes it according to device capabilitie
260
261 If the device is an endpoint, a unique device
262 is written into the device's Base Device ID CS
263
264 If the device is a switch, the enumerator allo
265 structure to store switch specific information
266 device ID are queried against a table of known
267 table entry contains a pointer to a switch-spe
268 initializes pointers to the rest of switch spe
269 hardware initialization if necessary. A RapidI
270 device ID; it relies on hopcount and routing f
271 endpoint if access to its configuration regist
272 chain of switches) does not have any endpoint
273 it, a fake device ID will be assigned to confi
274 In the case of a chain of switches without end
275 to configure a route through the entire chain
276 their hopcount value.
277
278 For both endpoints and switches the enumerator
279 into device's Component Tag CSR. That unique v
280 management notification mechanism to identify
281 error management event.
282
283 Enumeration beyond a switch is completed by it
284 port of that switch. For each active link, a r
285 (0xFF for 8-bit systems and 0xFFFF for 16-bit
286 into the routing table. The algorithm recurs b
287 and the default device ID in order to access t
288
289 After the host has completed enumeration of th
290 devices by clearing device ID locks (calls rio
291 in the system, it sets the Discovered bit in t
292 to indicate that enumeration is completed and
293 passive discovery of the network.
294
295 The discovery process is performed by agents a
296 process that is described above. However, the
297 without changes to the existing routing becaus
298 about RapidIO network structure and are buildi
299 devices. This way each Linux-based component o
300 a complete view of the network. The discovery
301 simultaneously by several agents. After initia
302 each agent waits for enumeration completion by
303 time period. If this wait time period expires
304 an agent skips RapidIO discovery and continues
305 initialization.
306
307 4.5 Adding New Enumeration/Discovery Method
308 -------------------------------------------
309
310 RapidIO subsystem code organization allows add
311 methods as new configuration options without s
312 RapidIO code.
313
314 A new enumeration/discovery method has to be a
315 devices before an enumeration/discovery proces
316 method's module initialization routine calls r
317 an enumerator to a specified mport device (or
318 implementation demonstrates this process.
319
320 4.6 Using Loadable RapidIO Switch Drivers
321 -----------------------------------------
322
323 In the case when RapidIO switch drivers are bu
324 must ensure that they are loaded before the en
325 This process can be automated by specifying pr
326 RapidIO-specific modprobe configuration file a
327
328 File /etc/modprobe.d/rapidio.conf::
329
330 # Configure RapidIO subsystem modules
331
332 # Set enumerator host destination ID (overri
333 options rapidio hdid=-1,2
334
335 # Load RapidIO switch drivers immediately af
336 softdep rapidio post: idt_gen2 idtcps tsi57x
337
338 # OR :
339
340 # Load RapidIO switch drivers just before ri
341 softdep rio-scan pre: idt_gen2 idtcps tsi57x
342
343 --------------------------
344
345 NOTE:
346 In the example above, one of "softdep" comma
347 commented out to keep required module loadin
348
349 5. References
350 =============
351
352 [1] RapidIO Trade Association. RapidIO Interco
353 http://www.rapidio.org.
354
355 [2] Rapidio TA. Technology Comparisons.
356 http://www.rapidio.org/education/technolog
357
358 [3] RapidIO support for Linux.
359 https://lwn.net/Articles/139118/
360
361 [4] Matt Porter. RapidIO for Linux. Ottawa Lin
362 https://www.kernel.org/doc/ols/2005/ols200
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