driver-api/rapidio/rapidio.rst

5 The RapidIO standard is a packet-based fabric interconnect standard designed for
8 is publicly available for download from the RTA web-site [1].
17 into the kernel similarly to other buses by defining RapidIO-specific device and
21 architecture-specific interfaces that provide support for common RapidIO
33 ---------------
50 ----------
53 All devices are presented in the RapidIO subsystem by corresponding rio_dev data
54 structure. Devices form one global device list and per-network device lists
58 ----------
68 specific switch drivers that are designed to provide hardware-specific
72 -----------
74 A RapidIO network is a combination of interconnected endpoint and switch devices.
76 data structure. This structure includes lists of all devices and local master
77 ports that form the same network. It also contains a pointer to the default
78 master port that is used to communicate with devices within the network.
81 ------------------
83 RapidIO device-specific drivers follow Linux Kernel Driver Model and are
84 intended to support specific RapidIO devices attached to the RapidIO network.
87 ------------------------
90 one or more common service layers for all participating RapidIO devices. These
91 common services may act separately from device-specific drivers or be used by
92 device-specific drivers. Example of such service provider is the RIONET driver
93 which implements Ethernet-over-RapidIO interface. Because only one driver can be
96 the same device without blocking attachment of a device-specific driver.
108 by user-space command.
117 ------------
119 RapidIO subsystem configuration options allow users to build enumeration and
125 Depending on selected enumeration/discovery build configuration, there are
132   'rio-scan.scan' for existing basic enumeration/discovery method.
138   expires the discovery process is terminated without obtaining RapidIO network
140   a user-space command as it is described below (if the given endpoint was
147   started first by issuing a user-space command, after an enumeration is
152   process can be started by issuing a user-space command.
165 on RapidIO subsystem build configuration:
170   the command line parameter "rapidio.hdid=-1,7" will result in assignment of
172   one will be assigned destination ID=-1.
178   - from command line: "modprobe rapidio hdid=-1,7", or
179   - from modprobe configuration file using configuration command "options",
180     like in this example: "options rapidio hdid=-1,7". An example of modprobe
185   destination ID = -1;
188   destination ID assignments omitted from the end of list (default = -1).
190 If the host device ID for a specific master port is set to -1, the discovery
194 to access the configuration space of devices.
196 NOTE: If RapidIO switch-specific device drivers are built as loadable modules
199 vendor-specific callbacks on early stages.
202 ------------------------------------------------
204 Automatic enumeration/discovery start method is applicable only to built-in
207 command line parameter "rio-scan.scan=1".
218 discovery for all known mport devices.
224 4.3 User-space Start of Enumeration and Discovery
225 -------------------------------------------------
227 User-space start of enumeration and discovery can be used with built-in and
228 modular build configurations. For user-space controlled start RapidIO subsystem
229 creates the sysfs write-only attribute file '/sys/bus/rapidio/scan'. To initiate
237 write '-1' (or RIO_MPORT_ANY) into the scan attribute file.
240 ----------------------------
254 The enumeration process traverses the network using a recursive depth-first
267 table entry contains a pointer to a switch-specific initialization routine that
274 In the case of a chain of switches without endpoint, one fake device ID is used
284 port of that switch. For each active link, a route to a default device ID
285 (0xFF for 8-bit systems and 0xFFFF for 16-bit systems) is temporarily written
287 and the default device ID in order to access the device on the active port.
290 devices by clearing device ID locks (calls rio_clear_locks()). For each endpoint
297 without changes to the existing routing because agents only gather information
299 devices. This way each Linux-based component of the RapidIO subsystem has
308 -------------------------------------------
311 methods as new configuration options without significant impact to the core
315 devices before an enumeration/discovery process can be started. Normally,
317 an enumerator to a specified mport device (or devices). The basic enumerator
321 -----------------------------------------
325 This process can be automated by specifying pre- or post- dependencies in the
326 RapidIO-specific modprobe configuration file as shown in the example below.
333   options rapidio hdid=-1,2
340   # Load RapidIO switch drivers just before rio-scan enumerator module is loaded
341   softdep rio-scan pre: idt_gen2 idtcps tsi57x
343   --------------------------
362     https://www.kernel.org/doc/ols/2005/ols2005v2-pages-43-56.pdf