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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> | |
17 | <year>2003</year> | |
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 | ||
47 | <chapter id="libataThanks"> | |
48 | <title>Thanks</title> | |
49 | <para> | |
50 | The bulk of the ATA knowledge comes thanks to long conversations with | |
51 | Andre Hedrick (www.linux-ide.org). | |
52 | </para> | |
53 | <para> | |
54 | Thanks to Alan Cox for pointing out similarities | |
55 | between SATA and SCSI, and in general for motivation to hack on | |
56 | libata. | |
57 | </para> | |
58 | <para> | |
59 | libata's device detection | |
60 | method, ata_pio_devchk, and in general all the early probing was | |
61 | based on extensive study of Hale Landis's probe/reset code in his | |
62 | ATADRVR driver (www.ata-atapi.com). | |
63 | </para> | |
64 | </chapter> | |
65 | ||
66 | <chapter id="libataDriverApi"> | |
67 | <title>libata Driver API</title> | |
68 | <sect1> | |
69 | <title>struct ata_port_operations</title> | |
70 | ||
71 | <programlisting> | |
72 | void (*port_disable) (struct ata_port *); | |
73 | </programlisting> | |
74 | ||
75 | <para> | |
76 | Called from ata_bus_probe() and ata_bus_reset() error paths, | |
77 | as well as when unregistering from the SCSI module (rmmod, hot | |
78 | unplug). | |
79 | </para> | |
80 | ||
81 | <programlisting> | |
82 | void (*dev_config) (struct ata_port *, struct ata_device *); | |
83 | </programlisting> | |
84 | ||
85 | <para> | |
86 | Called after IDENTIFY [PACKET] DEVICE is issued to each device | |
87 | found. Typically used to apply device-specific fixups prior to | |
88 | issue of SET FEATURES - XFER MODE, and prior to operation. | |
89 | </para> | |
90 | ||
91 | <programlisting> | |
92 | void (*set_piomode) (struct ata_port *, struct ata_device *); | |
93 | void (*set_dmamode) (struct ata_port *, struct ata_device *); | |
94 | void (*post_set_mode) (struct ata_port *ap); | |
95 | </programlisting> | |
96 | ||
97 | <para> | |
98 | Hooks called prior to the issue of SET FEATURES - XFER MODE | |
99 | command. dev->pio_mode is guaranteed to be valid when | |
100 | ->set_piomode() is called, and dev->dma_mode is guaranteed to be | |
101 | valid when ->set_dmamode() is called. ->post_set_mode() is | |
102 | called unconditionally, after the SET FEATURES - XFER MODE | |
103 | command completes successfully. | |
104 | </para> | |
105 | ||
106 | <para> | |
107 | ->set_piomode() is always called (if present), but | |
108 | ->set_dma_mode() is only called if DMA is possible. | |
109 | </para> | |
110 | ||
111 | <programlisting> | |
112 | void (*tf_load) (struct ata_port *ap, struct ata_taskfile *tf); | |
113 | void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf); | |
114 | </programlisting> | |
115 | ||
116 | <para> | |
117 | ->tf_load() is called to load the given taskfile into hardware | |
118 | registers / DMA buffers. ->tf_read() is called to read the | |
119 | hardware registers / DMA buffers, to obtain the current set of | |
120 | taskfile register values. | |
121 | </para> | |
122 | ||
123 | <programlisting> | |
124 | void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf); | |
125 | </programlisting> | |
126 | ||
127 | <para> | |
128 | causes an ATA command, previously loaded with | |
129 | ->tf_load(), to be initiated in hardware. | |
130 | </para> | |
131 | ||
132 | <programlisting> | |
133 | u8 (*check_status)(struct ata_port *ap); | |
134 | void (*dev_select)(struct ata_port *ap, unsigned int device); | |
135 | </programlisting> | |
136 | ||
137 | <para> | |
138 | Reads the Status ATA shadow register from hardware. On some | |
139 | hardware, this has the side effect of clearing the interrupt | |
140 | condition. | |
141 | </para> | |
142 | ||
143 | <programlisting> | |
144 | void (*dev_select)(struct ata_port *ap, unsigned int device); | |
145 | </programlisting> | |
146 | ||
147 | <para> | |
148 | Issues the low-level hardware command(s) that causes one of N | |
149 | hardware devices to be considered 'selected' (active and | |
150 | available for use) on the ATA bus. | |
151 | </para> | |
152 | ||
153 | <programlisting> | |
154 | void (*phy_reset) (struct ata_port *ap); | |
155 | </programlisting> | |
156 | ||
157 | <para> | |
158 | The very first step in the probe phase. Actions vary depending | |
159 | on the bus type, typically. After waking up the device and probing | |
160 | for device presence (PATA and SATA), typically a soft reset | |
161 | (SRST) will be performed. Drivers typically use the helper | |
162 | functions ata_bus_reset() or sata_phy_reset() for this hook. | |
163 | </para> | |
164 | ||
165 | <programlisting> | |
166 | void (*bmdma_setup) (struct ata_queued_cmd *qc); | |
167 | void (*bmdma_start) (struct ata_queued_cmd *qc); | |
168 | </programlisting> | |
169 | ||
170 | <para> | |
171 | When setting up an IDE BMDMA transaction, these hooks arm | |
172 | (->bmdma_setup) and fire (->bmdma_start) the hardware's DMA | |
173 | engine. | |
174 | </para> | |
175 | ||
176 | <programlisting> | |
177 | void (*qc_prep) (struct ata_queued_cmd *qc); | |
178 | int (*qc_issue) (struct ata_queued_cmd *qc); | |
179 | </programlisting> | |
180 | ||
181 | <para> | |
182 | Higher-level hooks, these two hooks can potentially supercede | |
183 | several of the above taskfile/DMA engine hooks. ->qc_prep is | |
184 | called after the buffers have been DMA-mapped, and is typically | |
185 | used to populate the hardware's DMA scatter-gather table. | |
186 | Most drivers use the standard ata_qc_prep() helper function, but | |
187 | more advanced drivers roll their own. | |
188 | </para> | |
189 | <para> | |
190 | ->qc_issue is used to make a command active, once the hardware | |
191 | and S/G tables have been prepared. IDE BMDMA drivers use the | |
192 | helper function ata_qc_issue_prot() for taskfile protocol-based | |
193 | dispatch. More advanced drivers roll their own ->qc_issue | |
194 | implementation, using this as the "issue new ATA command to | |
195 | hardware" hook. | |
196 | </para> | |
197 | ||
198 | <programlisting> | |
199 | void (*eng_timeout) (struct ata_port *ap); | |
200 | </programlisting> | |
201 | ||
202 | <para> | |
203 | This is a high level error handling function, called from the | |
204 | error handling thread, when a command times out. | |
205 | </para> | |
206 | ||
207 | <programlisting> | |
208 | irqreturn_t (*irq_handler)(int, void *, struct pt_regs *); | |
209 | void (*irq_clear) (struct ata_port *); | |
210 | </programlisting> | |
211 | ||
212 | <para> | |
213 | ->irq_handler is the interrupt handling routine registered with | |
214 | the system, by libata. ->irq_clear is called during probe just | |
215 | before the interrupt handler is registered, to be sure hardware | |
216 | is quiet. | |
217 | </para> | |
218 | ||
219 | <programlisting> | |
220 | u32 (*scr_read) (struct ata_port *ap, unsigned int sc_reg); | |
221 | void (*scr_write) (struct ata_port *ap, unsigned int sc_reg, | |
222 | u32 val); | |
223 | </programlisting> | |
224 | ||
225 | <para> | |
226 | Read and write standard SATA phy registers. Currently only used | |
227 | if ->phy_reset hook called the sata_phy_reset() helper function. | |
228 | </para> | |
229 | ||
230 | <programlisting> | |
231 | int (*port_start) (struct ata_port *ap); | |
232 | void (*port_stop) (struct ata_port *ap); | |
233 | void (*host_stop) (struct ata_host_set *host_set); | |
234 | </programlisting> | |
235 | ||
236 | <para> | |
237 | ->port_start() is called just after the data structures for each | |
238 | port are initialized. Typically this is used to alloc per-port | |
239 | DMA buffers / tables / rings, enable DMA engines, and similar | |
240 | tasks. | |
241 | </para> | |
242 | <para> | |
243 | ->host_stop() is called when the rmmod or hot unplug process | |
244 | begins. The hook must stop all hardware interrupts, DMA | |
245 | engines, etc. | |
246 | </para> | |
247 | <para> | |
248 | ->port_stop() is called after ->host_stop(). It's sole function | |
249 | is to release DMA/memory resources, now that they are no longer | |
250 | actively being used. | |
251 | </para> | |
252 | ||
253 | </sect1> | |
254 | </chapter> | |
255 | ||
256 | <chapter id="libataExt"> | |
257 | <title>libata Library</title> | |
258 | !Edrivers/scsi/libata-core.c | |
259 | </chapter> | |
260 | ||
261 | <chapter id="libataInt"> | |
262 | <title>libata Core Internals</title> | |
263 | !Idrivers/scsi/libata-core.c | |
264 | </chapter> | |
265 | ||
266 | <chapter id="libataScsiInt"> | |
267 | <title>libata SCSI translation/emulation</title> | |
268 | !Edrivers/scsi/libata-scsi.c | |
269 | !Idrivers/scsi/libata-scsi.c | |
270 | </chapter> | |
271 | ||
272 | <chapter id="PiixInt"> | |
273 | <title>ata_piix Internals</title> | |
274 | !Idrivers/scsi/ata_piix.c | |
275 | </chapter> | |
276 | ||
277 | <chapter id="SILInt"> | |
278 | <title>sata_sil Internals</title> | |
279 | !Idrivers/scsi/sata_sil.c | |
280 | </chapter> | |
281 | ||
282 | </book> |