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1da177e4 LT |
1 | The `parport' code provides parallel-port support under Linux. This |
2 | includes the ability to share one port between multiple device | |
3 | drivers. | |
4 | ||
5 | You can pass parameters to the parport code to override its automatic | |
6 | detection of your hardware. This is particularly useful if you want | |
7 | to use IRQs, since in general these can't be autoprobed successfully. | |
8 | By default IRQs are not used even if they _can_ be probed. This is | |
9 | because there are a lot of people using the same IRQ for their | |
10 | parallel port and a sound card or network card. | |
11 | ||
12 | The parport code is split into two parts: generic (which deals with | |
13 | port-sharing) and architecture-dependent (which deals with actually | |
14 | using the port). | |
15 | ||
16 | ||
17 | Parport as modules | |
18 | ================== | |
19 | ||
20 | If you load the parport code as a module, say | |
21 | ||
22 | # insmod parport | |
23 | ||
24 | to load the generic parport code. You then must load the | |
25 | architecture-dependent code with (for example): | |
26 | ||
27 | # insmod parport_pc io=0x3bc,0x378,0x278 irq=none,7,auto | |
28 | ||
29 | to tell the parport code that you want three PC-style ports, one at | |
30 | 0x3bc with no IRQ, one at 0x378 using IRQ 7, and one at 0x278 with an | |
31 | auto-detected IRQ. Currently, PC-style (parport_pc), Sun `bpp', | |
32 | Amiga, Atari, and MFC3 hardware is supported. | |
33 | ||
34 | PCI parallel I/O card support comes from parport_pc. Base I/O | |
35 | addresses should not be specified for supported PCI cards since they | |
36 | are automatically detected. | |
37 | ||
38 | ||
970e2486 LDM |
39 | modprobe |
40 | -------- | |
1da177e4 | 41 | |
970e2486 LDM |
42 | If you use modprobe , you will find it useful to add lines as below to a |
43 | configuration file in /etc/modprobe.d/ directory:. | |
1da177e4 LT |
44 | |
45 | alias parport_lowlevel parport_pc | |
46 | options parport_pc io=0x378,0x278 irq=7,auto | |
47 | ||
970e2486 LDM |
48 | modprobe will load parport_pc (with the options "io=0x378,0x278 irq=7,auto") |
49 | whenever a parallel port device driver (such as lp) is loaded. | |
1da177e4 LT |
50 | |
51 | Note that these are example lines only! You shouldn't in general need | |
52 | to specify any options to parport_pc in order to be able to use a | |
53 | parallel port. | |
54 | ||
55 | ||
56 | Parport probe [optional] | |
57 | ------------- | |
58 | ||
59 | In 2.2 kernels there was a module called parport_probe, which was used | |
60 | for collecting IEEE 1284 device ID information. This has now been | |
61 | enhanced and now lives with the IEEE 1284 support. When a parallel | |
62 | port is detected, the devices that are connected to it are analysed, | |
63 | and information is logged like this: | |
64 | ||
65 | parport0: Printer, BJC-210 (Canon) | |
66 | ||
67 | The probe information is available from files in /proc/sys/dev/parport/. | |
68 | ||
69 | ||
70 | Parport linked into the kernel statically | |
71 | ========================================= | |
72 | ||
73 | If you compile the parport code into the kernel, then you can use | |
74 | kernel boot parameters to get the same effect. Add something like the | |
75 | following to your LILO command line: | |
76 | ||
77 | parport=0x3bc parport=0x378,7 parport=0x278,auto,nofifo | |
78 | ||
79 | You can have many `parport=...' statements, one for each port you want | |
80 | to add. Adding `parport=0' to the kernel command-line will disable | |
81 | parport support entirely. Adding `parport=auto' to the kernel | |
82 | command-line will make parport use any IRQ lines or DMA channels that | |
83 | it auto-detects. | |
84 | ||
85 | ||
86 | Files in /proc | |
87 | ============== | |
88 | ||
89 | If you have configured the /proc filesystem into your kernel, you will | |
90 | see a new directory entry: /proc/sys/dev/parport. In there will be a | |
91 | directory entry for each parallel port for which parport is | |
92 | configured. In each of those directories are a collection of files | |
93 | describing that parallel port. | |
94 | ||
95 | The /proc/sys/dev/parport directory tree looks like: | |
96 | ||
97 | parport | |
98 | |-- default | |
99 | | |-- spintime | |
100 | | `-- timeslice | |
101 | |-- parport0 | |
102 | | |-- autoprobe | |
103 | | |-- autoprobe0 | |
104 | | |-- autoprobe1 | |
105 | | |-- autoprobe2 | |
106 | | |-- autoprobe3 | |
107 | | |-- devices | |
108 | | | |-- active | |
109 | | | `-- lp | |
110 | | | `-- timeslice | |
111 | | |-- base-addr | |
112 | | |-- irq | |
113 | | |-- dma | |
114 | | |-- modes | |
115 | | `-- spintime | |
116 | `-- parport1 | |
117 | |-- autoprobe | |
118 | |-- autoprobe0 | |
119 | |-- autoprobe1 | |
120 | |-- autoprobe2 | |
121 | |-- autoprobe3 | |
122 | |-- devices | |
123 | | |-- active | |
124 | | `-- ppa | |
125 | | `-- timeslice | |
126 | |-- base-addr | |
127 | |-- irq | |
128 | |-- dma | |
129 | |-- modes | |
130 | `-- spintime | |
131 | ||
132 | ||
133 | File: Contents: | |
134 | ||
135 | devices/active A list of the device drivers using that port. A "+" | |
136 | will appear by the name of the device currently using | |
137 | the port (it might not appear against any). The | |
138 | string "none" means that there are no device drivers | |
139 | using that port. | |
140 | ||
141 | base-addr Parallel port's base address, or addresses if the port | |
142 | has more than one in which case they are separated | |
143 | with tabs. These values might not have any sensible | |
144 | meaning for some ports. | |
145 | ||
146 | irq Parallel port's IRQ, or -1 if none is being used. | |
147 | ||
148 | dma Parallel port's DMA channel, or -1 if none is being | |
149 | used. | |
150 | ||
151 | modes Parallel port's hardware modes, comma-separated, | |
152 | meaning: | |
153 | ||
154 | PCSPP PC-style SPP registers are available. | |
155 | TRISTATE Port is bidirectional. | |
156 | COMPAT Hardware acceleration for printers is | |
157 | available and will be used. | |
158 | EPP Hardware acceleration for EPP protocol | |
159 | is available and will be used. | |
160 | ECP Hardware acceleration for ECP protocol | |
161 | is available and will be used. | |
162 | DMA DMA is available and will be used. | |
163 | ||
164 | Note that the current implementation will only take | |
165 | advantage of COMPAT and ECP modes if it has an IRQ | |
166 | line to use. | |
167 | ||
168 | autoprobe Any IEEE-1284 device ID information that has been | |
169 | acquired from the (non-IEEE 1284.3) device. | |
170 | ||
171 | autoprobe[0-3] IEEE 1284 device ID information retrieved from | |
172 | daisy-chain devices that conform to IEEE 1284.3. | |
173 | ||
174 | spintime The number of microseconds to busy-loop while waiting | |
175 | for the peripheral to respond. You might find that | |
176 | adjusting this improves performance, depending on your | |
177 | peripherals. This is a port-wide setting, i.e. it | |
178 | applies to all devices on a particular port. | |
179 | ||
180 | timeslice The number of milliseconds that a device driver is | |
181 | allowed to keep a port claimed for. This is advisory, | |
182 | and driver can ignore it if it must. | |
183 | ||
184 | default/* The defaults for spintime and timeslice. When a new | |
185 | port is registered, it picks up the default spintime. | |
186 | When a new device is registered, it picks up the | |
187 | default timeslice. | |
188 | ||
189 | Device drivers | |
190 | ============== | |
191 | ||
192 | Once the parport code is initialised, you can attach device drivers to | |
193 | specific ports. Normally this happens automatically; if the lp driver | |
194 | is loaded it will create one lp device for each port found. You can | |
195 | override this, though, by using parameters either when you load the lp | |
196 | driver: | |
197 | ||
198 | # insmod lp parport=0,2 | |
199 | ||
200 | or on the LILO command line: | |
201 | ||
202 | lp=parport0 lp=parport2 | |
203 | ||
204 | Both the above examples would inform lp that you want /dev/lp0 to be | |
205 | the first parallel port, and /dev/lp1 to be the _third_ parallel port, | |
206 | with no lp device associated with the second port (parport1). Note | |
207 | that this is different to the way older kernels worked; there used to | |
208 | be a static association between the I/O port address and the device | |
209 | name, so /dev/lp0 was always the port at 0x3bc. This is no longer the | |
210 | case - if you only have one port, it will default to being /dev/lp0, | |
211 | regardless of base address. | |
212 | ||
213 | Also: | |
214 | ||
215 | * If you selected the IEEE 1284 support at compile time, you can say | |
216 | `lp=auto' on the kernel command line, and lp will create devices | |
217 | only for those ports that seem to have printers attached. | |
218 | ||
219 | * If you give PLIP the `timid' parameter, either with `plip=timid' on | |
220 | the command line, or with `insmod plip timid=1' when using modules, | |
221 | it will avoid any ports that seem to be in use by other devices. | |
222 | ||
223 | * IRQ autoprobing works only for a few port types at the moment. | |
224 | ||
225 | Reporting printer problems with parport | |
226 | ======================================= | |
227 | ||
228 | If you are having problems printing, please go through these steps to | |
229 | try to narrow down where the problem area is. | |
230 | ||
231 | When reporting problems with parport, really you need to give all of | |
232 | the messages that parport_pc spits out when it initialises. There are | |
233 | several code paths: | |
234 | ||
235 | o polling | |
236 | o interrupt-driven, protocol in software | |
237 | o interrupt-driven, protocol in hardware using PIO | |
238 | o interrupt-driven, protocol in hardware using DMA | |
239 | ||
240 | The kernel messages that parport_pc logs give an indication of which | |
241 | code path is being used. (They could be a lot better actually..) | |
242 | ||
243 | For normal printer protocol, having IEEE 1284 modes enabled or not | |
244 | should not make a difference. | |
245 | ||
246 | To turn off the 'protocol in hardware' code paths, disable | |
247 | CONFIG_PARPORT_PC_FIFO. Note that when they are enabled they are not | |
248 | necessarily _used_; it depends on whether the hardware is available, | |
249 | enabled by the BIOS, and detected by the driver. | |
250 | ||
251 | So, to start with, disable CONFIG_PARPORT_PC_FIFO, and load parport_pc | |
252 | with 'irq=none'. See if printing works then. It really should, | |
253 | because this is the simplest code path. | |
254 | ||
255 | If that works fine, try with 'io=0x378 irq=7' (adjust for your | |
256 | hardware), to make it use interrupt-driven in-software protocol. | |
257 | ||
258 | If _that_ works fine, then one of the hardware modes isn't working | |
259 | right. Enable CONFIG_PARPORT_PC_FIFO (no, it isn't a module option, | |
260 | and yes, it should be), set the port to ECP mode in the BIOS and note | |
261 | the DMA channel, and try with: | |
262 | ||
263 | io=0x378 irq=7 dma=none (for PIO) | |
264 | io=0x378 irq=7 dma=3 (for DMA) | |
265 | -- | |
266 | philb@gnu.org | |
267 | tim@cyberelk.net |