1 .. SPDX-License-Identifier: GPL-2.0
7 The SAS Layer is a management infrastructure which manages
8 SAS LLDDs. It sits between SCSI Core and SAS LLDDs. The
9 layout is as follows: while SCSI Core is concerned with
10 SAM/SPC issues, and a SAS LLDD+sequencer is concerned with
11 phy/OOB/link management, the SAS layer is concerned with:
13 * SAS Phy/Port/HA event management (LLDD generates,
15 * SAS Port management (creation/destruction),
16 * SAS Domain discovery and revalidation,
17 * SAS Domain device management,
18 * SCSI Host registration/unregistration,
19 * Device registration with SCSI Core (SAS) or libata
21 * Expander management and exporting expander control
24 A SAS LLDD is a PCI device driver. It is concerned with
25 phy/OOB management, and vendor specific tasks and generates
26 events to the SAS layer.
28 The SAS Layer does most SAS tasks as outlined in the SAS 1.1
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 fields need to
33 be initialized by the LLDDs.
35 After initializing your hardware, from the probe() function
36 you call sas_register_ha(). It will register your LLDD with
37 the SCSI subsystem, creating a SCSI host and it will
38 register your SAS driver with the sysfs SAS tree it creates.
39 It will then return. Then you enable your phys to actually
40 start OOB (at which point your driver will start calling the
41 notify_* event callbacks).
43 Structure descriptions
44 ======================
49 Normally this is statically embedded to your driver's
54 struct sas_phy sas_phy;
58 And then all the phys are an array of my_phy in your HA
61 Then as you go along and initialize your phys you also
62 initialize the sas_phy struct, along with your own
65 In general, the phys are managed by the LLDD and the ports
66 are managed by the SAS layer. So the phys are initialized
67 and updated by the LLDD and the ports are initialized and
68 updated by the SAS layer.
70 There is a scheme where the LLDD can RW certain fields,
71 and the SAS layer can only read such ones, and vice versa.
72 The idea is to avoid unnecessary locking.
78 - must be set [0,MAX_PHYS)]
80 class, proto, type, role, oob_mode, linkrate
84 - you set this when OOB has finished and then notify
88 - this normally points to an array holding the sas
89 address of the phy, possibly somewhere in your my_phy
93 - set this when you (LLDD) receive an
94 IDENTIFY frame or a FIS frame, _before_ notifying the SAS
95 layer. The idea is that sometimes the LLDD may want to fake
96 or provide a different SAS address on that phy/port and this
97 allows it to do this. At best you should copy the sas
98 address from the IDENTIFY frame or maybe generate a SAS
99 address for SATA directly attached devices. The Discover
100 process may later change this.
103 - this is where you copy the IDENTIFY/FIS frame
104 when you get it; you lock, copy, set frame_rcvd_size and
105 unlock the lock, and then call the event. It is a pointer
106 since there's no way to know your hw frame size _exactly_,
107 so you define the actual array in your phy struct and let
108 this pointer point to it. You copy the frame from your
109 DMAable memory to that area holding the lock.
112 - this is where primitives go when they're
113 received. See sas.h. Grab the lock, set the primitive,
114 release the lock, notify.
117 - this points to the sas_port if the phy belongs
118 to a port -- the LLDD only reads this. It points to the
119 sas_port this phy is part of. Set by the SAS Layer.
122 - may be set; the SAS layer sets it anyway.
125 - you should set this to point to your phy so you
126 can find your way around faster when the SAS layer calls one
127 of your callbacks and passes you a phy. If the sas_phy is
128 embedded you can also use container_of -- whatever you
135 The LLDD doesn't set any fields of this struct -- it only
136 reads them. They should be self explanatory.
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.
142 - I haven't found use for that -- maybe other
143 LLDD who wish to have internal port representation can make
146 ``struct sas_ha_struct``
147 ------------------------
149 It normally is statically declared in your own LLDD
150 structure describing your adapter::
154 struct sas_ha_struct sas_ha;
155 struct my_phy phys[MAX_PHYS];
156 struct sas_port sas_ports[MAX_PHYS]; /* (1) */
160 (1) If your LLDD doesn't have its own port representation.
162 What needs to be initialized (sample function given below).
168 - since the SAS layer doesn't want to mess with
169 memory allocation, etc, this points to statically
170 allocated array somewhere (say in your host adapter
171 structure) and holds the SAS address of the host
172 adapter as given by you or the manufacturer, etc.
178 - an array of pointers to structures. (see
179 note above on sas_addr).
180 These must be set. See more notes below.
183 - the number of phys present in the sas_phy array,
184 and the number of ports present in the sas_port
185 array. There can be a maximum num_phys ports (one per
186 port) so we drop the num_ports, and only use
189 The event interface::
191 /* LLDD calls these to notify the class of an event. */
192 void (*notify_ha_event)(struct sas_ha_struct *, enum ha_event);
193 void (*notify_port_event)(struct sas_phy *, enum port_event);
194 void (*notify_phy_event)(struct sas_phy *, enum phy_event);
196 When sas_register_ha() returns, those are set and can be
197 called by the LLDD to notify the SAS layer of such events
200 The port notification::
202 /* The class calls these to notify the LLDD of an event. */
203 void (*lldd_port_formed)(struct sas_phy *);
204 void (*lldd_port_deformed)(struct sas_phy *);
206 If the LLDD wants notification when a port has been formed
207 or deformed it sets those to a function satisfying the type.
209 A SAS LLDD should also implement at least one of the Task
210 Management Functions (TMFs) described in SAM::
212 /* Task Management Functions. Must be called from process context. */
213 int (*lldd_abort_task)(struct sas_task *);
214 int (*lldd_abort_task_set)(struct domain_device *, u8 *lun);
215 int (*lldd_clear_aca)(struct domain_device *, u8 *lun);
216 int (*lldd_clear_task_set)(struct domain_device *, u8 *lun);
217 int (*lldd_I_T_nexus_reset)(struct domain_device *);
218 int (*lldd_lu_reset)(struct domain_device *, u8 *lun);
219 int (*lldd_query_task)(struct sas_task *);
221 For more information please read SAM from T10.org.
223 Port and Adapter management::
225 /* Port and Adapter management */
226 int (*lldd_clear_nexus_port)(struct sas_port *);
227 int (*lldd_clear_nexus_ha)(struct sas_ha_struct *);
229 A SAS LLDD should implement at least one of those.
234 int (*lldd_control_phy)(struct sas_phy *, enum phy_func);
237 - set this to point to your HA struct. You can also
238 use container_of if you embedded it as shown above.
240 A sample initialization and registration function
241 can look like this (called last thing from probe())
242 *but* before you enable the phys to do OOB::
244 static int register_sas_ha(struct my_sas_ha *my_ha)
247 static struct sas_phy *sas_phys[MAX_PHYS];
248 static struct sas_port *sas_ports[MAX_PHYS];
250 my_ha->sas_ha.sas_addr = &my_ha->sas_addr[0];
252 for (i = 0; i < MAX_PHYS; i++) {
253 sas_phys[i] = &my_ha->phys[i].sas_phy;
254 sas_ports[i] = &my_ha->sas_ports[i];
257 my_ha->sas_ha.sas_phy = sas_phys;
258 my_ha->sas_ha.sas_port = sas_ports;
259 my_ha->sas_ha.num_phys = MAX_PHYS;
261 my_ha->sas_ha.lldd_port_formed = my_port_formed;
263 my_ha->sas_ha.lldd_dev_found = my_dev_found;
264 my_ha->sas_ha.lldd_dev_gone = my_dev_gone;
266 my_ha->sas_ha.lldd_execute_task = my_execute_task;
268 my_ha->sas_ha.lldd_abort_task = my_abort_task;
269 my_ha->sas_ha.lldd_abort_task_set = my_abort_task_set;
270 my_ha->sas_ha.lldd_clear_aca = my_clear_aca;
271 my_ha->sas_ha.lldd_clear_task_set = my_clear_task_set;
272 my_ha->sas_ha.lldd_I_T_nexus_reset= NULL; (2)
273 my_ha->sas_ha.lldd_lu_reset = my_lu_reset;
274 my_ha->sas_ha.lldd_query_task = my_query_task;
276 my_ha->sas_ha.lldd_clear_nexus_port = my_clear_nexus_port;
277 my_ha->sas_ha.lldd_clear_nexus_ha = my_clear_nexus_ha;
279 my_ha->sas_ha.lldd_control_phy = my_control_phy;
281 return sas_register_ha(&my_ha->sas_ha);
284 (2) SAS 1.1 does not define I_T Nexus Reset TMF.
289 Events are **the only way** a SAS LLDD notifies the SAS layer
290 of anything. There is no other method or way a LLDD to tell
291 the SAS layer of anything happening internally or in the SAS
296 PHYE_LOSS_OF_SIGNAL, (C)
301 Port events, passed on a _phy_::
303 PORTE_BYTES_DMAED, (M)
304 PORTE_BROADCAST_RCVD, (E)
305 PORTE_LINK_RESET_ERR, (C)
306 PORTE_TIMER_EVENT, (C)
312 A SAS LLDD should be able to generate
314 - at least one event from group C (choice),
315 - events marked M (mandatory) are mandatory (only one),
316 - events marked E (expander) if it wants the SAS layer
317 to handle domain revalidation (only one such).
318 - Unmarked events are optional.
323 - when your HA got internal error and was reset.
326 - on receiving an IDENTIFY/FIS frame
329 - on receiving a primitive
332 - timer expired, loss of signal, loss of DWS, etc. [1]_
335 - DWS reset timeout timer expired [1]_
338 - Hard Reset primitive received.
341 - the device is gone [1]_
344 - OOB went fine and oob_mode is valid
347 - Error while doing OOB, the device probably
348 got disconnected. [1]_
351 - SATA is present, COMWAKE not sent.
353 .. [1] should set/clear the appropriate fields in the phy,
354 or alternatively call the inlined sas_phy_disconnected()
355 which is just a helper, from their tasklet.
357 The Execute Command SCSI RPC::
359 int (*lldd_execute_task)(struct sas_task *, gfp_t gfp_flags);
361 Used to queue a task to the SAS LLDD. @task is the task to be executed.
362 @gfp_mask is the gfp_mask defining the context of the caller.
364 This function should implement the Execute Command SCSI RPC,
366 That is, when lldd_execute_task() is called, the command
367 go out on the transport *immediately*. There is *no*
368 queuing of any sort and at any level in a SAS LLDD.
372 * -SAS_QUEUE_FULL, -ENOMEM, nothing was queued;
373 * 0, the task(s) were queued.
378 dev -- the device this task is destined to
379 task_proto -- _one_ of enum sas_proto
380 scatter -- pointer to scatter gather list array
381 num_scatter -- number of elements in scatter
382 total_xfer_len -- total number of bytes expected to be transferred
383 data_dir -- PCI_DMA_...
384 task_done -- callback when the task has finished execution
390 The sysfs tree has the following purposes:
392 a) It shows you the physical layout of the SAS domain at
393 the current time, i.e. how the domain looks in the
394 physical world right now.
395 b) Shows some device parameters _at_discovery_time_.
397 This is a link to the tree(1) program, very useful in
398 viewing the SAS domain:
399 ftp://mama.indstate.edu/linux/tree/
401 I expect user space applications to actually create a
402 graphical interface of this.
404 That is, the sysfs domain tree doesn't show or keep state if
405 you e.g., change the meaning of the READY LED MEANING
406 setting, but it does show you the current connection status
407 of the domain device.
409 Keeping internal device state changes is responsibility of
410 upper layers (Command set drivers) and user space.
412 When a device or devices are unplugged from the domain, this
413 is reflected in the sysfs tree immediately, and the device(s)
414 removed from the system.
416 The structure domain_device describes any device in the SAS
417 domain. It is completely managed by the SAS layer. A task
418 points to a domain device, this is how the SAS LLDD knows
419 where to send the task(s) to. A SAS LLDD only reads the
420 contents of the domain_device structure, but it never creates
423 Expander management from User Space
424 ===================================
426 In each expander directory in sysfs, there is a file called
427 "smp_portal". It is a binary sysfs attribute file, which
428 implements an SMP portal (Note: this is *NOT* an SMP port),
429 to which user space applications can send SMP requests and
430 receive SMP responses.
432 Functionality is deceptively simple:
434 1. Build the SMP frame you want to send. The format and layout
435 is described in the SAS spec. Leave the CRC field equal 0.
439 2. Open the expander's SMP portal sysfs file in RW mode.
443 3. Write the frame you built in 1.
447 4. Read the amount of data you expect to receive for the frame you built.
448 If you receive different amount of data you expected to receive,
449 then there was some kind of error.
453 All this process is shown in detail in the function do_smp_func()
454 and its callers, in the file "expander_conf.c".
456 The kernel functionality is implemented in the file
459 The program "expander_conf.c" implements this. It takes one
460 argument, the sysfs file name of the SMP portal to the
461 expander, and gives expander information, including routing
464 The SMP portal gives you complete control of the expander,
465 so please be careful.