]>
Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | <?xml version="1.0" encoding="UTF-8"?> |
2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> | |
4 | ||
5 | <book id="libataDevGuide"> | |
6 | <bookinfo> | |
7 | <title>libATA Developer's Guide</title> | |
8 | ||
9 | <authorgroup> | |
10 | <author> | |
11 | <firstname>Jeff</firstname> | |
12 | <surname>Garzik</surname> | |
13 | </author> | |
14 | </authorgroup> | |
15 | ||
16 | <copyright> | |
780a87f7 | 17 | <year>2003-2005</year> |
1da177e4 LT |
18 | <holder>Jeff Garzik</holder> |
19 | </copyright> | |
20 | ||
21 | <legalnotice> | |
22 | <para> | |
23 | The contents of this file are subject to the Open | |
24 | Software License version 1.1 that can be found at | |
25 | <ulink url="http://www.opensource.org/licenses/osl-1.1.txt">http://www.opensource.org/licenses/osl-1.1.txt</ulink> and is included herein | |
26 | by reference. | |
27 | </para> | |
28 | ||
29 | <para> | |
30 | Alternatively, the contents of this file may be used under the terms | |
31 | of the GNU General Public License version 2 (the "GPL") as distributed | |
32 | in the kernel source COPYING file, in which case the provisions of | |
33 | the GPL are applicable instead of the above. If you wish to allow | |
34 | the use of your version of this file only under the terms of the | |
35 | GPL and not to allow others to use your version of this file under | |
36 | the OSL, indicate your decision by deleting the provisions above and | |
37 | replace them with the notice and other provisions required by the GPL. | |
38 | If you do not delete the provisions above, a recipient may use your | |
39 | version of this file under either the OSL or the GPL. | |
40 | </para> | |
41 | ||
42 | </legalnotice> | |
43 | </bookinfo> | |
44 | ||
45 | <toc></toc> | |
46 | ||
07dd39b9 JG |
47 | <chapter id="libataIntroduction"> |
48 | <title>Introduction</title> | |
49 | <para> | |
50 | libATA is a library used inside the Linux kernel to support ATA host | |
51 | controllers and devices. libATA provides an ATA driver API, class | |
52 | transports for ATA and ATAPI devices, and SCSI<->ATA translation | |
53 | for ATA devices according to the T10 SAT specification. | |
54 | </para> | |
55 | <para> | |
56 | This Guide documents the libATA driver API, library functions, library | |
57 | internals, and a couple sample ATA low-level drivers. | |
58 | </para> | |
59 | </chapter> | |
60 | ||
1da177e4 LT |
61 | <chapter id="libataDriverApi"> |
62 | <title>libata Driver API</title> | |
63 | <sect1> | |
64 | <title>struct ata_port_operations</title> | |
65 | ||
66 | <programlisting> | |
67 | void (*port_disable) (struct ata_port *); | |
68 | </programlisting> | |
69 | ||
70 | <para> | |
71 | Called from ata_bus_probe() and ata_bus_reset() error paths, | |
72 | as well as when unregistering from the SCSI module (rmmod, hot | |
73 | unplug). | |
74 | </para> | |
75 | ||
76 | <programlisting> | |
77 | void (*dev_config) (struct ata_port *, struct ata_device *); | |
78 | </programlisting> | |
79 | ||
80 | <para> | |
81 | Called after IDENTIFY [PACKET] DEVICE is issued to each device | |
82 | found. Typically used to apply device-specific fixups prior to | |
83 | issue of SET FEATURES - XFER MODE, and prior to operation. | |
84 | </para> | |
85 | ||
86 | <programlisting> | |
87 | void (*set_piomode) (struct ata_port *, struct ata_device *); | |
88 | void (*set_dmamode) (struct ata_port *, struct ata_device *); | |
89 | void (*post_set_mode) (struct ata_port *ap); | |
90 | </programlisting> | |
91 | ||
92 | <para> | |
93 | Hooks called prior to the issue of SET FEATURES - XFER MODE | |
94 | command. dev->pio_mode is guaranteed to be valid when | |
95 | ->set_piomode() is called, and dev->dma_mode is guaranteed to be | |
96 | valid when ->set_dmamode() is called. ->post_set_mode() is | |
97 | called unconditionally, after the SET FEATURES - XFER MODE | |
98 | command completes successfully. | |
99 | </para> | |
100 | ||
101 | <para> | |
102 | ->set_piomode() is always called (if present), but | |
103 | ->set_dma_mode() is only called if DMA is possible. | |
104 | </para> | |
105 | ||
106 | <programlisting> | |
107 | void (*tf_load) (struct ata_port *ap, struct ata_taskfile *tf); | |
108 | void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf); | |
109 | </programlisting> | |
110 | ||
111 | <para> | |
112 | ->tf_load() is called to load the given taskfile into hardware | |
113 | registers / DMA buffers. ->tf_read() is called to read the | |
114 | hardware registers / DMA buffers, to obtain the current set of | |
115 | taskfile register values. | |
116 | </para> | |
117 | ||
118 | <programlisting> | |
119 | void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf); | |
120 | </programlisting> | |
121 | ||
122 | <para> | |
123 | causes an ATA command, previously loaded with | |
124 | ->tf_load(), to be initiated in hardware. | |
125 | </para> | |
126 | ||
780a87f7 JG |
127 | <programlisting> |
128 | int (*check_atapi_dma) (struct ata_queued_cmd *qc); | |
129 | </programlisting> | |
130 | ||
131 | <para> | |
132 | Allow low-level driver to filter ATA PACKET commands, returning a status | |
133 | indicating whether or not it is OK to use DMA for the supplied PACKET | |
134 | command. | |
135 | </para> | |
136 | ||
1da177e4 LT |
137 | <programlisting> |
138 | u8 (*check_status)(struct ata_port *ap); | |
780a87f7 JG |
139 | u8 (*check_altstatus)(struct ata_port *ap); |
140 | u8 (*check_err)(struct ata_port *ap); | |
1da177e4 LT |
141 | </programlisting> |
142 | ||
143 | <para> | |
780a87f7 JG |
144 | Reads the Status/AltStatus/Error ATA shadow register from |
145 | hardware. On some hardware, reading the Status register has | |
146 | the side effect of clearing the interrupt condition. | |
1da177e4 LT |
147 | </para> |
148 | ||
149 | <programlisting> | |
150 | void (*dev_select)(struct ata_port *ap, unsigned int device); | |
151 | </programlisting> | |
152 | ||
153 | <para> | |
154 | Issues the low-level hardware command(s) that causes one of N | |
155 | hardware devices to be considered 'selected' (active and | |
780a87f7 JG |
156 | available for use) on the ATA bus. This generally has no |
157 | meaning on FIS-based devices. | |
1da177e4 LT |
158 | </para> |
159 | ||
160 | <programlisting> | |
161 | void (*phy_reset) (struct ata_port *ap); | |
162 | </programlisting> | |
163 | ||
164 | <para> | |
165 | The very first step in the probe phase. Actions vary depending | |
166 | on the bus type, typically. After waking up the device and probing | |
167 | for device presence (PATA and SATA), typically a soft reset | |
168 | (SRST) will be performed. Drivers typically use the helper | |
169 | functions ata_bus_reset() or sata_phy_reset() for this hook. | |
170 | </para> | |
171 | ||
172 | <programlisting> | |
173 | void (*bmdma_setup) (struct ata_queued_cmd *qc); | |
174 | void (*bmdma_start) (struct ata_queued_cmd *qc); | |
780a87f7 JG |
175 | void (*bmdma_stop) (struct ata_port *ap); |
176 | u8 (*bmdma_status) (struct ata_port *ap); | |
1da177e4 LT |
177 | </programlisting> |
178 | ||
179 | <para> | |
780a87f7 JG |
180 | When setting up an IDE BMDMA transaction, these hooks arm |
181 | (->bmdma_setup), fire (->bmdma_start), and halt (->bmdma_stop) | |
182 | the hardware's DMA engine. ->bmdma_status is used to read the standard | |
183 | PCI IDE DMA Status register. | |
184 | </para> | |
185 | ||
186 | <para> | |
187 | These hooks are typically either no-ops, or simply not implemented, in | |
188 | FIS-based drivers. | |
1da177e4 LT |
189 | </para> |
190 | ||
191 | <programlisting> | |
192 | void (*qc_prep) (struct ata_queued_cmd *qc); | |
193 | int (*qc_issue) (struct ata_queued_cmd *qc); | |
194 | </programlisting> | |
195 | ||
196 | <para> | |
197 | Higher-level hooks, these two hooks can potentially supercede | |
198 | several of the above taskfile/DMA engine hooks. ->qc_prep is | |
199 | called after the buffers have been DMA-mapped, and is typically | |
200 | used to populate the hardware's DMA scatter-gather table. | |
201 | Most drivers use the standard ata_qc_prep() helper function, but | |
202 | more advanced drivers roll their own. | |
203 | </para> | |
204 | <para> | |
205 | ->qc_issue is used to make a command active, once the hardware | |
206 | and S/G tables have been prepared. IDE BMDMA drivers use the | |
207 | helper function ata_qc_issue_prot() for taskfile protocol-based | |
780a87f7 | 208 | dispatch. More advanced drivers implement their own ->qc_issue. |
1da177e4 LT |
209 | </para> |
210 | ||
211 | <programlisting> | |
212 | void (*eng_timeout) (struct ata_port *ap); | |
213 | </programlisting> | |
214 | ||
215 | <para> | |
780a87f7 JG |
216 | This is a high level error handling function, called from the |
217 | error handling thread, when a command times out. Most newer | |
218 | hardware will implement its own error handling code here. IDE BMDMA | |
219 | drivers may use the helper function ata_eng_timeout(). | |
1da177e4 LT |
220 | </para> |
221 | ||
222 | <programlisting> | |
223 | irqreturn_t (*irq_handler)(int, void *, struct pt_regs *); | |
224 | void (*irq_clear) (struct ata_port *); | |
225 | </programlisting> | |
226 | ||
227 | <para> | |
228 | ->irq_handler is the interrupt handling routine registered with | |
229 | the system, by libata. ->irq_clear is called during probe just | |
230 | before the interrupt handler is registered, to be sure hardware | |
231 | is quiet. | |
232 | </para> | |
233 | ||
234 | <programlisting> | |
235 | u32 (*scr_read) (struct ata_port *ap, unsigned int sc_reg); | |
236 | void (*scr_write) (struct ata_port *ap, unsigned int sc_reg, | |
237 | u32 val); | |
238 | </programlisting> | |
239 | ||
240 | <para> | |
241 | Read and write standard SATA phy registers. Currently only used | |
242 | if ->phy_reset hook called the sata_phy_reset() helper function. | |
243 | </para> | |
244 | ||
245 | <programlisting> | |
246 | int (*port_start) (struct ata_port *ap); | |
247 | void (*port_stop) (struct ata_port *ap); | |
248 | void (*host_stop) (struct ata_host_set *host_set); | |
249 | </programlisting> | |
250 | ||
251 | <para> | |
252 | ->port_start() is called just after the data structures for each | |
253 | port are initialized. Typically this is used to alloc per-port | |
254 | DMA buffers / tables / rings, enable DMA engines, and similar | |
255 | tasks. | |
256 | </para> | |
257 | <para> | |
1da177e4 LT |
258 | ->port_stop() is called after ->host_stop(). It's sole function |
259 | is to release DMA/memory resources, now that they are no longer | |
260 | actively being used. | |
261 | </para> | |
780a87f7 JG |
262 | <para> |
263 | ->host_stop() is called after all ->port_stop() calls | |
264 | have completed. The hook must finalize hardware shutdown, release DMA | |
265 | and other resources, etc. | |
266 | </para> | |
1da177e4 LT |
267 | |
268 | </sect1> | |
269 | </chapter> | |
270 | ||
271 | <chapter id="libataExt"> | |
272 | <title>libata Library</title> | |
273 | !Edrivers/scsi/libata-core.c | |
274 | </chapter> | |
275 | ||
276 | <chapter id="libataInt"> | |
277 | <title>libata Core Internals</title> | |
278 | !Idrivers/scsi/libata-core.c | |
279 | </chapter> | |
280 | ||
281 | <chapter id="libataScsiInt"> | |
282 | <title>libata SCSI translation/emulation</title> | |
283 | !Edrivers/scsi/libata-scsi.c | |
284 | !Idrivers/scsi/libata-scsi.c | |
285 | </chapter> | |
286 | ||
287 | <chapter id="PiixInt"> | |
288 | <title>ata_piix Internals</title> | |
289 | !Idrivers/scsi/ata_piix.c | |
290 | </chapter> | |
291 | ||
292 | <chapter id="SILInt"> | |
293 | <title>sata_sil Internals</title> | |
294 | !Idrivers/scsi/sata_sil.c | |
295 | </chapter> | |
296 | ||
0cba632b JG |
297 | <chapter id="libataThanks"> |
298 | <title>Thanks</title> | |
299 | <para> | |
300 | The bulk of the ATA knowledge comes thanks to long conversations with | |
301 | Andre Hedrick (www.linux-ide.org), and long hours pondering the ATA | |
302 | and SCSI specifications. | |
303 | </para> | |
304 | <para> | |
305 | Thanks to Alan Cox for pointing out similarities | |
306 | between SATA and SCSI, and in general for motivation to hack on | |
307 | libata. | |
308 | </para> | |
309 | <para> | |
310 | libata's device detection | |
311 | method, ata_pio_devchk, and in general all the early probing was | |
312 | based on extensive study of Hale Landis's probe/reset code in his | |
313 | ATADRVR driver (www.ata-atapi.com). | |
314 | </para> | |
315 | </chapter> | |
316 | ||
1da177e4 | 317 | </book> |