1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 ========= 3 =========
4 SAS Layer 4 SAS Layer
5 ========= 5 =========
6 6
7 The SAS Layer is a management infrastructure w 7 The SAS Layer is a management infrastructure which manages
8 SAS LLDDs. It sits between SCSI Core and SAS 8 SAS LLDDs. It sits between SCSI Core and SAS LLDDs. The
9 layout is as follows: while SCSI Core is conce 9 layout is as follows: while SCSI Core is concerned with
10 SAM/SPC issues, and a SAS LLDD+sequencer is co 10 SAM/SPC issues, and a SAS LLDD+sequencer is concerned with
11 phy/OOB/link management, the SAS layer is conc 11 phy/OOB/link management, the SAS layer is concerned with:
12 12
13 * SAS Phy/Port/HA event management (LLDD 13 * SAS Phy/Port/HA event management (LLDD generates,
14 SAS Layer processes), 14 SAS Layer processes),
15 * SAS Port management (creation/destruct 15 * SAS Port management (creation/destruction),
16 * SAS Domain discovery and revalidation, 16 * SAS Domain discovery and revalidation,
17 * SAS Domain device management, 17 * SAS Domain device management,
18 * SCSI Host registration/unregistration, 18 * SCSI Host registration/unregistration,
19 * Device registration with SCSI Core (SA 19 * Device registration with SCSI Core (SAS) or libata
20 (SATA), and 20 (SATA), and
21 * Expander management and exporting expa 21 * Expander management and exporting expander control
22 to user space. 22 to user space.
23 23
24 A SAS LLDD is a PCI device driver. It is conc 24 A SAS LLDD is a PCI device driver. It is concerned with
25 phy/OOB management, and vendor specific tasks 25 phy/OOB management, and vendor specific tasks and generates
26 events to the SAS layer. 26 events to the SAS layer.
27 27
28 The SAS Layer does most SAS tasks as outlined 28 The SAS Layer does most SAS tasks as outlined in the SAS 1.1
29 spec. 29 spec.
30 30
31 The sas_ha_struct describes the SAS LLDD to th 31 The sas_ha_struct describes the SAS LLDD to the SAS layer.
32 Most of it is used by the SAS Layer but a few 32 Most of it is used by the SAS Layer but a few fields need to
33 be initialized by the LLDDs. 33 be initialized by the LLDDs.
34 34
35 After initializing your hardware, from the pro 35 After initializing your hardware, from the probe() function
36 you call sas_register_ha(). It will register y 36 you call sas_register_ha(). It will register your LLDD with
37 the SCSI subsystem, creating a SCSI host and i 37 the SCSI subsystem, creating a SCSI host and it will
38 register your SAS driver with the sysfs SAS tr 38 register your SAS driver with the sysfs SAS tree it creates.
39 It will then return. Then you enable your phy 39 It will then return. Then you enable your phys to actually
40 start OOB (at which point your driver will sta 40 start OOB (at which point your driver will start calling the
41 notify_* event callbacks). 41 notify_* event callbacks).
42 42
43 Structure descriptions 43 Structure descriptions
44 ====================== 44 ======================
45 45
46 ``struct sas_phy`` 46 ``struct sas_phy``
47 ------------------ 47 ------------------
48 48
49 Normally this is statically embedded to your d 49 Normally this is statically embedded to your driver's
50 phy structure:: 50 phy structure::
51 51
52 struct my_phy { 52 struct my_phy {
53 blah; 53 blah;
54 struct sas_phy sas_phy; 54 struct sas_phy sas_phy;
55 bleh; 55 bleh;
56 }; 56 };
57 57
58 And then all the phys are an array of my_phy i 58 And then all the phys are an array of my_phy in your HA
59 struct (shown below). 59 struct (shown below).
60 60
61 Then as you go along and initialize your phys 61 Then as you go along and initialize your phys you also
62 initialize the sas_phy struct, along with your 62 initialize the sas_phy struct, along with your own
63 phy structure. 63 phy structure.
64 64
65 In general, the phys are managed by the LLDD a 65 In general, the phys are managed by the LLDD and the ports
66 are managed by the SAS layer. So the phys are 66 are managed by the SAS layer. So the phys are initialized
67 and updated by the LLDD and the ports are init 67 and updated by the LLDD and the ports are initialized and
68 updated by the SAS layer. 68 updated by the SAS layer.
69 69
70 There is a scheme where the LLDD can RW certai 70 There is a scheme where the LLDD can RW certain fields,
71 and the SAS layer can only read such ones, and 71 and the SAS layer can only read such ones, and vice versa.
72 The idea is to avoid unnecessary locking. 72 The idea is to avoid unnecessary locking.
73 73
74 enabled 74 enabled
75 - must be set (0/1) 75 - must be set (0/1)
76 76
77 id 77 id
78 - must be set [0,MAX_PHYS)] 78 - must be set [0,MAX_PHYS)]
79 79
80 class, proto, type, role, oob_mode, linkrate 80 class, proto, type, role, oob_mode, linkrate
81 - must be set 81 - must be set
82 82
83 oob_mode 83 oob_mode
84 - you set this when OOB has finished and t 84 - you set this when OOB has finished and then notify
85 the SAS Layer. 85 the SAS Layer.
86 86
87 sas_addr 87 sas_addr
88 - this normally points to an array holding 88 - this normally points to an array holding the sas
89 address of the phy, possibly somewhere i 89 address of the phy, possibly somewhere in your my_phy
90 struct. 90 struct.
91 91
92 attached_sas_addr 92 attached_sas_addr
93 - set this when you (LLDD) receive an 93 - set this when you (LLDD) receive an
94 IDENTIFY frame or a FIS frame, _before_ 94 IDENTIFY frame or a FIS frame, _before_ notifying the SAS
95 layer. The idea is that sometimes the L 95 layer. The idea is that sometimes the LLDD may want to fake
96 or provide a different SAS address on th 96 or provide a different SAS address on that phy/port and this
97 allows it to do this. At best you shoul 97 allows it to do this. At best you should copy the sas
98 address from the IDENTIFY frame or maybe 98 address from the IDENTIFY frame or maybe generate a SAS
99 address for SATA directly attached devic 99 address for SATA directly attached devices. The Discover
100 process may later change this. 100 process may later change this.
101 101
102 frame_rcvd 102 frame_rcvd
103 - this is where you copy the IDENTIFY/FIS 103 - this is where you copy the IDENTIFY/FIS frame
104 when you get it; you lock, copy, set fra 104 when you get it; you lock, copy, set frame_rcvd_size and
105 unlock the lock, and then call the event 105 unlock the lock, and then call the event. It is a pointer
106 since there's no way to know your hw fra 106 since there's no way to know your hw frame size _exactly_,
107 so you define the actual array in your p 107 so you define the actual array in your phy struct and let
108 this pointer point to it. You copy the 108 this pointer point to it. You copy the frame from your
109 DMAable memory to that area holding the 109 DMAable memory to that area holding the lock.
110 110
111 sas_prim 111 sas_prim
112 - this is where primitives go when they're 112 - this is where primitives go when they're
113 received. See sas.h. Grab the lock, set 113 received. See sas.h. Grab the lock, set the primitive,
114 release the lock, notify. 114 release the lock, notify.
115 115
116 port 116 port
117 - this points to the sas_port if the phy b 117 - this points to the sas_port if the phy belongs
118 to a port -- the LLDD only reads this. I 118 to a port -- the LLDD only reads this. It points to the
119 sas_port this phy is part of. Set by th 119 sas_port this phy is part of. Set by the SAS Layer.
120 120
121 ha 121 ha
122 - may be set; the SAS layer sets it anyway 122 - may be set; the SAS layer sets it anyway.
123 123
124 lldd_phy 124 lldd_phy
125 - you should set this to point to your phy 125 - you should set this to point to your phy so you
126 can find your way around faster when the 126 can find your way around faster when the SAS layer calls one
127 of your callbacks and passes you a phy. 127 of your callbacks and passes you a phy. If the sas_phy is
128 embedded you can also use container_of - 128 embedded you can also use container_of -- whatever you
129 prefer. 129 prefer.
130 130
131 131
132 ``struct sas_port`` 132 ``struct sas_port``
133 ------------------- 133 -------------------
134 134
135 The LLDD doesn't set any fields of this struct 135 The LLDD doesn't set any fields of this struct -- it only
136 reads them. They should be self explanatory. 136 reads them. They should be self explanatory.
137 137
138 phy_mask is 32 bit, this should be enough for 138 phy_mask is 32 bit, this should be enough for now, as I
139 haven't heard of a HA having more than 8 phys. 139 haven't heard of a HA having more than 8 phys.
140 140
141 lldd_port 141 lldd_port
142 - I haven't found use for that -- maybe ot 142 - I haven't found use for that -- maybe other
143 LLDD who wish to have internal port repr 143 LLDD who wish to have internal port representation can make
144 use of this. 144 use of this.
145 145
146 ``struct sas_ha_struct`` 146 ``struct sas_ha_struct``
147 ------------------------ 147 ------------------------
148 148
149 It normally is statically declared in your own 149 It normally is statically declared in your own LLDD
150 structure describing your adapter:: 150 structure describing your adapter::
151 151
152 struct my_sas_ha { 152 struct my_sas_ha {
153 blah; 153 blah;
154 struct sas_ha_struct sas_ha; 154 struct sas_ha_struct sas_ha;
155 struct my_phy phys[MAX_PHYS]; 155 struct my_phy phys[MAX_PHYS];
156 struct sas_port sas_ports[MAX_PHYS]; / 156 struct sas_port sas_ports[MAX_PHYS]; /* (1) */
157 bleh; 157 bleh;
158 }; 158 };
159 159
160 (1) If your LLDD doesn't have its own port 160 (1) If your LLDD doesn't have its own port representation.
161 161
162 What needs to be initialized (sample function 162 What needs to be initialized (sample function given below).
163 163
164 pcidev 164 pcidev
165 ^^^^^^ 165 ^^^^^^
166 166
167 sas_addr 167 sas_addr
168 - since the SAS layer doesn't want to m 168 - since the SAS layer doesn't want to mess with
169 memory allocation, etc, this points t 169 memory allocation, etc, this points to statically
170 allocated array somewhere (say in you 170 allocated array somewhere (say in your host adapter
171 structure) and holds the SAS address 171 structure) and holds the SAS address of the host
172 adapter as given by you or the manufa 172 adapter as given by you or the manufacturer, etc.
173 173
174 sas_port 174 sas_port
175 ^^^^^^^^ 175 ^^^^^^^^
176 176
177 sas_phy 177 sas_phy
178 - an array of pointers to structures. (s 178 - an array of pointers to structures. (see
179 note above on sas_addr). 179 note above on sas_addr).
180 These must be set. See more notes bel 180 These must be set. See more notes below.
181 181
182 num_phys 182 num_phys
183 - the number of phys present in the sas 183 - the number of phys present in the sas_phy array,
184 and the number of ports present in th 184 and the number of ports present in the sas_port
185 array. There can be a maximum num_ph 185 array. There can be a maximum num_phys ports (one per
186 port) so we drop the num_ports, and o 186 port) so we drop the num_ports, and only use
187 num_phys. 187 num_phys.
188 188
189 The event interface:: 189 The event interface::
190 190
191 /* LLDD calls these to notify the clas 191 /* LLDD calls these to notify the class of an event. */
192 void sas_notify_port_event(struct sas_ 192 void sas_notify_port_event(struct sas_phy *, enum port_event, gfp_t);
193 void sas_notify_phy_event(struct sas_p 193 void sas_notify_phy_event(struct sas_phy *, enum phy_event, gfp_t);
194 194
195 The port notification:: 195 The port notification::
196 196
197 /* The class calls these to notify the 197 /* The class calls these to notify the LLDD of an event. */
198 void (*lldd_port_formed)(struct sas_ph 198 void (*lldd_port_formed)(struct sas_phy *);
199 void (*lldd_port_deformed)(struct sas_ 199 void (*lldd_port_deformed)(struct sas_phy *);
200 200
201 If the LLDD wants notification when a port has 201 If the LLDD wants notification when a port has been formed
202 or deformed it sets those to a function satisf 202 or deformed it sets those to a function satisfying the type.
203 203
204 A SAS LLDD should also implement at least one 204 A SAS LLDD should also implement at least one of the Task
205 Management Functions (TMFs) described in SAM:: 205 Management Functions (TMFs) described in SAM::
206 206
207 /* Task Management Functions. Must be 207 /* Task Management Functions. Must be called from process context. */
208 int (*lldd_abort_task)(struct sas_task 208 int (*lldd_abort_task)(struct sas_task *);
209 int (*lldd_abort_task_set)(struct doma 209 int (*lldd_abort_task_set)(struct domain_device *, u8 *lun);
>> 210 int (*lldd_clear_aca)(struct domain_device *, u8 *lun);
210 int (*lldd_clear_task_set)(struct doma 211 int (*lldd_clear_task_set)(struct domain_device *, u8 *lun);
211 int (*lldd_I_T_nexus_reset)(struct dom 212 int (*lldd_I_T_nexus_reset)(struct domain_device *);
212 int (*lldd_lu_reset)(struct domain_dev 213 int (*lldd_lu_reset)(struct domain_device *, u8 *lun);
213 int (*lldd_query_task)(struct sas_task 214 int (*lldd_query_task)(struct sas_task *);
214 215
215 For more information please read SAM from T10. 216 For more information please read SAM from T10.org.
216 217
217 Port and Adapter management:: 218 Port and Adapter management::
218 219
219 /* Port and Adapter management */ 220 /* Port and Adapter management */
220 int (*lldd_clear_nexus_port)(struct sa 221 int (*lldd_clear_nexus_port)(struct sas_port *);
221 int (*lldd_clear_nexus_ha)(struct sas_ 222 int (*lldd_clear_nexus_ha)(struct sas_ha_struct *);
222 223
223 A SAS LLDD should implement at least one of th 224 A SAS LLDD should implement at least one of those.
224 225
225 Phy management:: 226 Phy management::
226 227
227 /* Phy management */ 228 /* Phy management */
228 int (*lldd_control_phy)(struct sas_phy 229 int (*lldd_control_phy)(struct sas_phy *, enum phy_func);
229 230
230 lldd_ha 231 lldd_ha
231 - set this to point to your HA struct. You 232 - set this to point to your HA struct. You can also
232 use container_of if you embedded it as s 233 use container_of if you embedded it as shown above.
233 234
234 A sample initialization and registration funct 235 A sample initialization and registration function
235 can look like this (called last thing from pro 236 can look like this (called last thing from probe())
236 *but* before you enable the phys to do OOB:: 237 *but* before you enable the phys to do OOB::
237 238
238 static int register_sas_ha(struct my_sas_h 239 static int register_sas_ha(struct my_sas_ha *my_ha)
239 { 240 {
240 int i; 241 int i;
241 static struct sas_phy *sas_phys[ 242 static struct sas_phy *sas_phys[MAX_PHYS];
242 static struct sas_port *sas_ports 243 static struct sas_port *sas_ports[MAX_PHYS];
243 244
244 my_ha->sas_ha.sas_addr = &my_ha->s 245 my_ha->sas_ha.sas_addr = &my_ha->sas_addr[0];
245 246
246 for (i = 0; i < MAX_PHYS; i++) { 247 for (i = 0; i < MAX_PHYS; i++) {
247 sas_phys[i] = &my_ha->phys 248 sas_phys[i] = &my_ha->phys[i].sas_phy;
248 sas_ports[i] = &my_ha->sas 249 sas_ports[i] = &my_ha->sas_ports[i];
249 } 250 }
250 251
251 my_ha->sas_ha.sas_phy = sas_phys; 252 my_ha->sas_ha.sas_phy = sas_phys;
252 my_ha->sas_ha.sas_port = sas_ports 253 my_ha->sas_ha.sas_port = sas_ports;
253 my_ha->sas_ha.num_phys = MAX_PHYS; 254 my_ha->sas_ha.num_phys = MAX_PHYS;
254 255
255 my_ha->sas_ha.lldd_port_formed = m 256 my_ha->sas_ha.lldd_port_formed = my_port_formed;
256 257
257 my_ha->sas_ha.lldd_dev_found = my_ 258 my_ha->sas_ha.lldd_dev_found = my_dev_found;
258 my_ha->sas_ha.lldd_dev_gone = my_d 259 my_ha->sas_ha.lldd_dev_gone = my_dev_gone;
259 260
260 my_ha->sas_ha.lldd_execute_task = 261 my_ha->sas_ha.lldd_execute_task = my_execute_task;
261 262
262 my_ha->sas_ha.lldd_abort_task 263 my_ha->sas_ha.lldd_abort_task = my_abort_task;
263 my_ha->sas_ha.lldd_abort_task_set 264 my_ha->sas_ha.lldd_abort_task_set = my_abort_task_set;
>> 265 my_ha->sas_ha.lldd_clear_aca = my_clear_aca;
264 my_ha->sas_ha.lldd_clear_task_set 266 my_ha->sas_ha.lldd_clear_task_set = my_clear_task_set;
265 my_ha->sas_ha.lldd_I_T_nexus_reset 267 my_ha->sas_ha.lldd_I_T_nexus_reset= NULL; (2)
266 my_ha->sas_ha.lldd_lu_reset 268 my_ha->sas_ha.lldd_lu_reset = my_lu_reset;
267 my_ha->sas_ha.lldd_query_task 269 my_ha->sas_ha.lldd_query_task = my_query_task;
268 270
269 my_ha->sas_ha.lldd_clear_nexus_por 271 my_ha->sas_ha.lldd_clear_nexus_port = my_clear_nexus_port;
270 my_ha->sas_ha.lldd_clear_nexus_ha 272 my_ha->sas_ha.lldd_clear_nexus_ha = my_clear_nexus_ha;
271 273
272 my_ha->sas_ha.lldd_control_phy = m 274 my_ha->sas_ha.lldd_control_phy = my_control_phy;
273 275
274 return sas_register_ha(&my_ha->sas 276 return sas_register_ha(&my_ha->sas_ha);
275 } 277 }
276 278
277 (2) SAS 1.1 does not define I_T Nexus Reset TM 279 (2) SAS 1.1 does not define I_T Nexus Reset TMF.
278 280
279 Events 281 Events
280 ====== 282 ======
281 283
282 Events are **the only way** a SAS LLDD notifie 284 Events are **the only way** a SAS LLDD notifies the SAS layer
283 of anything. There is no other method or way 285 of anything. There is no other method or way a LLDD to tell
284 the SAS layer of anything happening internally 286 the SAS layer of anything happening internally or in the SAS
285 domain. 287 domain.
286 288
287 Phy events:: 289 Phy events::
288 290
289 PHYE_LOSS_OF_SIGNAL, (C) 291 PHYE_LOSS_OF_SIGNAL, (C)
290 PHYE_OOB_DONE, 292 PHYE_OOB_DONE,
291 PHYE_OOB_ERROR, (C) 293 PHYE_OOB_ERROR, (C)
292 PHYE_SPINUP_HOLD. 294 PHYE_SPINUP_HOLD.
293 295
294 Port events, passed on a _phy_:: 296 Port events, passed on a _phy_::
295 297
296 PORTE_BYTES_DMAED, (M) 298 PORTE_BYTES_DMAED, (M)
297 PORTE_BROADCAST_RCVD, (E) 299 PORTE_BROADCAST_RCVD, (E)
298 PORTE_LINK_RESET_ERR, (C) 300 PORTE_LINK_RESET_ERR, (C)
299 PORTE_TIMER_EVENT, (C) 301 PORTE_TIMER_EVENT, (C)
300 PORTE_HARD_RESET. 302 PORTE_HARD_RESET.
301 303
302 Host Adapter event: 304 Host Adapter event:
303 HAE_RESET 305 HAE_RESET
304 306
305 A SAS LLDD should be able to generate 307 A SAS LLDD should be able to generate
306 308
307 - at least one event from group C (cho 309 - at least one event from group C (choice),
308 - events marked M (mandatory) are mand 310 - events marked M (mandatory) are mandatory (only one),
309 - events marked E (expander) if it wan 311 - events marked E (expander) if it wants the SAS layer
310 to handle domain revalidation (only 312 to handle domain revalidation (only one such).
311 - Unmarked events are optional. 313 - Unmarked events are optional.
312 314
313 Meaning: 315 Meaning:
314 316
315 HAE_RESET 317 HAE_RESET
316 - when your HA got internal error and was 318 - when your HA got internal error and was reset.
317 319
318 PORTE_BYTES_DMAED 320 PORTE_BYTES_DMAED
319 - on receiving an IDENTIFY/FIS frame 321 - on receiving an IDENTIFY/FIS frame
320 322
321 PORTE_BROADCAST_RCVD 323 PORTE_BROADCAST_RCVD
322 - on receiving a primitive 324 - on receiving a primitive
323 325
324 PORTE_LINK_RESET_ERR 326 PORTE_LINK_RESET_ERR
325 - timer expired, loss of signal, loss of D 327 - timer expired, loss of signal, loss of DWS, etc. [1]_
326 328
327 PORTE_TIMER_EVENT 329 PORTE_TIMER_EVENT
328 - DWS reset timeout timer expired [1]_ 330 - DWS reset timeout timer expired [1]_
329 331
330 PORTE_HARD_RESET 332 PORTE_HARD_RESET
331 - Hard Reset primitive received. 333 - Hard Reset primitive received.
332 334
333 PHYE_LOSS_OF_SIGNAL 335 PHYE_LOSS_OF_SIGNAL
334 - the device is gone [1]_ 336 - the device is gone [1]_
335 337
336 PHYE_OOB_DONE 338 PHYE_OOB_DONE
337 - OOB went fine and oob_mode is valid 339 - OOB went fine and oob_mode is valid
338 340
339 PHYE_OOB_ERROR 341 PHYE_OOB_ERROR
340 - Error while doing OOB, the device probab 342 - Error while doing OOB, the device probably
341 got disconnected. [1]_ 343 got disconnected. [1]_
342 344
343 PHYE_SPINUP_HOLD 345 PHYE_SPINUP_HOLD
344 - SATA is present, COMWAKE not sent. 346 - SATA is present, COMWAKE not sent.
345 347
346 .. [1] should set/clear the appropriate fields 348 .. [1] should set/clear the appropriate fields in the phy,
347 or alternatively call the inlined sas_p 349 or alternatively call the inlined sas_phy_disconnected()
348 which is just a helper, from their task 350 which is just a helper, from their tasklet.
349 351
350 The Execute Command SCSI RPC:: 352 The Execute Command SCSI RPC::
351 353
352 int (*lldd_execute_task)(struct sas_ta 354 int (*lldd_execute_task)(struct sas_task *, gfp_t gfp_flags);
353 355
354 Used to queue a task to the SAS LLDD. @task i 356 Used to queue a task to the SAS LLDD. @task is the task to be executed.
355 @gfp_mask is the gfp_mask defining the context 357 @gfp_mask is the gfp_mask defining the context of the caller.
356 358
357 This function should implement the Execute Com 359 This function should implement the Execute Command SCSI RPC,
358 360
359 That is, when lldd_execute_task() is called, t 361 That is, when lldd_execute_task() is called, the command
360 go out on the transport *immediately*. There 362 go out on the transport *immediately*. There is *no*
361 queuing of any sort and at any level in a SAS 363 queuing of any sort and at any level in a SAS LLDD.
362 364
363 Returns: 365 Returns:
364 366
365 * -SAS_QUEUE_FULL, -ENOMEM, nothing was que 367 * -SAS_QUEUE_FULL, -ENOMEM, nothing was queued;
366 * 0, the task(s) were queued. 368 * 0, the task(s) were queued.
367 369
368 :: 370 ::
369 371
370 struct sas_task { 372 struct sas_task {
371 dev -- the device this task is des 373 dev -- the device this task is destined to
372 task_proto -- _one_ of enum sas_pr 374 task_proto -- _one_ of enum sas_proto
373 scatter -- pointer to scatter gath 375 scatter -- pointer to scatter gather list array
374 num_scatter -- number of elements 376 num_scatter -- number of elements in scatter
375 total_xfer_len -- total number of 377 total_xfer_len -- total number of bytes expected to be transferred
376 data_dir -- PCI_DMA_... 378 data_dir -- PCI_DMA_...
377 task_done -- callback when the tas 379 task_done -- callback when the task has finished execution
378 }; 380 };
379 381
380 Discovery 382 Discovery
381 ========= 383 =========
382 384
383 The sysfs tree has the following purposes: 385 The sysfs tree has the following purposes:
384 386
385 a) It shows you the physical layout of the 387 a) It shows you the physical layout of the SAS domain at
386 the current time, i.e. how the domain l 388 the current time, i.e. how the domain looks in the
387 physical world right now. 389 physical world right now.
388 b) Shows some device parameters _at_discov 390 b) Shows some device parameters _at_discovery_time_.
389 391
390 This is a link to the tree(1) program, very us 392 This is a link to the tree(1) program, very useful in
391 viewing the SAS domain: 393 viewing the SAS domain:
392 ftp://mama.indstate.edu/linux/tree/ 394 ftp://mama.indstate.edu/linux/tree/
393 395
394 I expect user space applications to actually c 396 I expect user space applications to actually create a
395 graphical interface of this. 397 graphical interface of this.
396 398
397 That is, the sysfs domain tree doesn't show or 399 That is, the sysfs domain tree doesn't show or keep state if
398 you e.g., change the meaning of the READY LED 400 you e.g., change the meaning of the READY LED MEANING
399 setting, but it does show you the current conn 401 setting, but it does show you the current connection status
400 of the domain device. 402 of the domain device.
401 403
402 Keeping internal device state changes is respo 404 Keeping internal device state changes is responsibility of
403 upper layers (Command set drivers) and user sp 405 upper layers (Command set drivers) and user space.
404 406
405 When a device or devices are unplugged from th 407 When a device or devices are unplugged from the domain, this
406 is reflected in the sysfs tree immediately, an 408 is reflected in the sysfs tree immediately, and the device(s)
407 removed from the system. 409 removed from the system.
408 410
409 The structure domain_device describes any devi 411 The structure domain_device describes any device in the SAS
410 domain. It is completely managed by the SAS l 412 domain. It is completely managed by the SAS layer. A task
411 points to a domain device, this is how the SAS 413 points to a domain device, this is how the SAS LLDD knows
412 where to send the task(s) to. A SAS LLDD only 414 where to send the task(s) to. A SAS LLDD only reads the
413 contents of the domain_device structure, but i 415 contents of the domain_device structure, but it never creates
414 or destroys one. 416 or destroys one.
415 417
416 Expander management from User Space 418 Expander management from User Space
417 =================================== 419 ===================================
418 420
419 In each expander directory in sysfs, there is 421 In each expander directory in sysfs, there is a file called
420 "smp_portal". It is a binary sysfs attribute 422 "smp_portal". It is a binary sysfs attribute file, which
421 implements an SMP portal (Note: this is *NOT* 423 implements an SMP portal (Note: this is *NOT* an SMP port),
422 to which user space applications can send SMP 424 to which user space applications can send SMP requests and
423 receive SMP responses. 425 receive SMP responses.
424 426
425 Functionality is deceptively simple: 427 Functionality is deceptively simple:
426 428
427 1. Build the SMP frame you want to send. The f 429 1. Build the SMP frame you want to send. The format and layout
428 is described in the SAS spec. Leave the CR 430 is described in the SAS spec. Leave the CRC field equal 0.
429 431
430 open(2) 432 open(2)
431 433
432 2. Open the expander's SMP portal sysfs file i 434 2. Open the expander's SMP portal sysfs file in RW mode.
433 435
434 write(2) 436 write(2)
435 437
436 3. Write the frame you built in 1. 438 3. Write the frame you built in 1.
437 439
438 read(2) 440 read(2)
439 441
440 4. Read the amount of data you expect to recei 442 4. Read the amount of data you expect to receive for the frame you built.
441 If you receive different amount of data you 443 If you receive different amount of data you expected to receive,
442 then there was some kind of error. 444 then there was some kind of error.
443 445
444 close(2) 446 close(2)
445 447
446 All this process is shown in detail in the fun 448 All this process is shown in detail in the function do_smp_func()
447 and its callers, in the file "expander_conf.c" 449 and its callers, in the file "expander_conf.c".
448 450
449 The kernel functionality is implemented in the 451 The kernel functionality is implemented in the file
450 "sas_expander.c". 452 "sas_expander.c".
451 453
452 The program "expander_conf.c" implements this. 454 The program "expander_conf.c" implements this. It takes one
453 argument, the sysfs file name of the SMP porta 455 argument, the sysfs file name of the SMP portal to the
454 expander, and gives expander information, incl 456 expander, and gives expander information, including routing
455 tables. 457 tables.
456 458
457 The SMP portal gives you complete control of t 459 The SMP portal gives you complete control of the expander,
458 so please be careful. 460 so please be careful.
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