Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/Documentation/hayes-esp.txt
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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File size: 6637 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | HAYES ESP DRIVER VERSION 2.1 |
2 | |
3 | A big thanks to the people at Hayes, especially Alan Adamson. Their support |
4 | has enabled me to provide enhancements to the driver. |
5 | |
6 | Please report your experiences with this driver to me (arobinso@nyx.net). I |
7 | am looking for both positive and negative feedback. |
8 | |
9 | *** IMPORTANT CHANGES FOR 2.1 *** |
10 | Support for PIO mode. Five situations will cause PIO mode to be used: |
11 | 1) A multiport card is detected. PIO mode will always be used. (8 port cards |
12 | do not support DMA). |
13 | 2) The DMA channel is set to an invalid value (anything other than 1 or 3). |
14 | 3) The DMA buffer/channel could not be allocated. The port will revert to PIO |
15 | mode until it is reopened. |
16 | 4) Less than a specified number of bytes need to be transferred to/from the |
17 | FIFOs. PIO mode will be used for that transfer only. |
18 | 5) A port needs to do a DMA transfer and another port is already using the |
19 | DMA channel. PIO mode will be used for that transfer only. |
20 | |
21 | Since the Hayes ESP seems to conflict with other cards (notably sound cards) |
22 | when using DMA, DMA is turned off by default. To use DMA, it must be turned |
23 | on explicitly, either with the "dma=" option described below or with |
24 | setserial. A multiport card can be forced into DMA mode by using setserial; |
25 | however, most multiport cards don't support DMA. |
26 | |
27 | The latest version of setserial allows the enhanced configuration of the ESP |
28 | card to be viewed and modified. |
29 | *** |
30 | |
31 | This package contains the files needed to compile a module to support the Hayes |
32 | ESP card. The drivers are basically a modified version of the serial drivers. |
33 | |
34 | Features: |
35 | |
36 | - Uses the enhanced mode of the ESP card, allowing a wider range of |
37 | interrupts and features than compatibility mode |
38 | - Uses DMA and 16 bit PIO mode to transfer data to and from the ESP's FIFOs, |
39 | reducing CPU load |
40 | - Supports primary and secondary ports |
41 | |
42 | |
43 | If the driver is compiled as a module, the IRQs to use can be specified by |
44 | using the irq= option. The format is: |
45 | |
46 | irq=[0x100],[0x140],[0x180],[0x200],[0x240],[0x280],[0x300],[0x380] |
47 | |
48 | The address in brackets is the base address of the card. The IRQ of |
49 | nonexistent cards can be set to 0. If an IRQ of a card that does exist is set |
50 | to 0, the driver will attempt to guess at the correct IRQ. For example, to set |
51 | the IRQ of the card at address 0x300 to 12, the insmod command would be: |
52 | |
53 | insmod esp irq=0,0,0,0,0,0,12,0 |
54 | |
55 | The custom divisor can be set by using the divisor= option. The format is the |
56 | same as for the irq= option. Each divisor value is a series of hex digits, |
57 | with each digit representing the divisor to use for a corresponding port. The |
58 | divisor value is constructed RIGHT TO LEFT. Specifying a nonzero divisor value |
59 | will automatically set the spd_cust flag. To calculate the divisor to use for |
60 | a certain baud rate, divide the port's base baud (generally 921600) by the |
61 | desired rate. For example, to set the divisor of the primary port at 0x300 to |
62 | 4 and the divisor of the secondary port at 0x308 to 8, the insmod command would |
63 | be: |
64 | |
65 | insmod esp divisor=0,0,0,0,0,0,0x84,0 |
66 | |
67 | The dma= option can be used to set the DMA channel. The channel can be either |
68 | 1 or 3. Specifying any other value will force the driver to use PIO mode. |
69 | For example, to set the DMA channel to 3, the insmod command would be: |
70 | |
71 | insmod esp dma=3 |
72 | |
73 | The rx_trigger= and tx_trigger= options can be used to set the FIFO trigger |
74 | levels. They specify when the ESP card should send an interrupt. Larger |
75 | values will decrease the number of interrupts; however, a value too high may |
76 | result in data loss. Valid values are 1 through 1023, with 768 being the |
77 | default. For example, to set the receive trigger level to 512 bytes and the |
78 | transmit trigger level to 700 bytes, the insmod command would be: |
79 | |
80 | insmod esp rx_trigger=512 tx_trigger=700 |
81 | |
82 | The flow_off= and flow_on= options can be used to set the hardware flow off/ |
83 | flow on levels. The flow on level must be lower than the flow off level, and |
84 | the flow off level should be higher than rx_trigger. Valid values are 1 |
85 | through 1023, with 1016 being the default flow off level and 944 being the |
86 | default flow on level. For example, to set the flow off level to 1000 bytes |
87 | and the flow on level to 935 bytes, the insmod command would be: |
88 | |
89 | insmod esp flow_off=1000 flow_on=935 |
90 | |
91 | The rx_timeout= option can be used to set the receive timeout value. This |
92 | value indicates how long after receiving the last character that the ESP card |
93 | should wait before signalling an interrupt. Valid values are 0 though 255, |
94 | with 128 being the default. A value too high will increase latency, and a |
95 | value too low will cause unnecessary interrupts. For example, to set the |
96 | receive timeout to 255, the insmod command would be: |
97 | |
98 | insmod esp rx_timeout=255 |
99 | |
100 | The pio_threshold= option sets the threshold (in number of characters) for |
101 | using PIO mode instead of DMA mode. For example, if this value is 32, |
102 | transfers of 32 bytes or less will always use PIO mode. |
103 | |
104 | insmod esp pio_threshold=32 |
105 | |
106 | Multiple options can be listed on the insmod command line by separating each |
107 | option with a space. For example: |
108 | |
109 | insmod esp dma=3 trigger=512 |
110 | |
111 | The esp module can be automatically loaded when needed. To cause this to |
112 | happen, add the following lines to /etc/modprobe.conf (replacing the last line |
113 | with options for your configuration): |
114 | |
115 | alias char-major-57 esp |
116 | alias char-major-58 esp |
117 | options esp irq=0,0,0,0,0,0,3,0 divisor=0,0,0,0,0,0,0x4,0 |
118 | |
119 | You may also need to run 'depmod -a'. |
120 | |
121 | Devices must be created manually. To create the devices, note the output from |
122 | the module after it is inserted. The output will appear in the location where |
123 | kernel messages usually appear (usually /var/adm/messages). Create two devices |
124 | for each 'tty' mentioned, one with major of 57 and the other with major of 58. |
125 | The minor number should be the same as the tty number reported. The commands |
126 | would be (replace ? with the tty number): |
127 | |
128 | mknod /dev/ttyP? c 57 ? |
129 | mknod /dev/cup? c 58 ? |
130 | |
131 | For example, if the following line appears: |
132 | |
133 | Oct 24 18:17:23 techno kernel: ttyP8 at 0x0140 (irq = 3) is an ESP primary port |
134 | |
135 | ...two devices should be created: |
136 | |
137 | mknod /dev/ttyP8 c 57 8 |
138 | mknod /dev/cup8 c 58 8 |
139 | |
140 | You may need to set the permissions on the devices: |
141 | |
142 | chmod 666 /dev/ttyP* |
143 | chmod 666 /dev/cup* |
144 | |
145 | The ESP module and the serial module should not conflict (they can be used at |
146 | the same time). After the ESP module has been loaded the ports on the ESP card |
147 | will no longer be accessible by the serial driver. |
148 | |
149 | If I/O errors are experienced when accessing the port, check for IRQ and DMA |
150 | conflicts ('cat /proc/interrupts' and 'cat /proc/dma' for a list of IRQs and |
151 | DMAs currently in use). |
152 | |
153 | Enjoy! |
154 | Andrew J. Robinson <arobinso@nyx.net> |