diff options
author | Ingo Molnar <mingo@elte.hu> | 2008-11-20 09:03:38 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-11-20 09:03:38 +0100 |
commit | 90accd6fabf9b2fa2705945a4c601877a75d43bf (patch) | |
tree | d393cb54f0228b1313139e4e14adf4f5cf236b59 /Documentation/serial/hayes-esp.txt | |
parent | b43d196c4d3fe46d6dda7c987c47792612b80b1b (diff) | |
parent | ee2f6cc7f9ea2542ad46070ed62ba7aa04d08871 (diff) |
Merge branch 'linus' into x86/memory-corruption-check
Diffstat (limited to 'Documentation/serial/hayes-esp.txt')
-rw-r--r-- | Documentation/serial/hayes-esp.txt | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/Documentation/serial/hayes-esp.txt b/Documentation/serial/hayes-esp.txt new file mode 100644 index 00000000000..09b5d585675 --- /dev/null +++ b/Documentation/serial/hayes-esp.txt @@ -0,0 +1,154 @@ +HAYES ESP DRIVER VERSION 2.1 + +A big thanks to the people at Hayes, especially Alan Adamson. Their support +has enabled me to provide enhancements to the driver. + +Please report your experiences with this driver to me (arobinso@nyx.net). I +am looking for both positive and negative feedback. + +*** IMPORTANT CHANGES FOR 2.1 *** +Support for PIO mode. Five situations will cause PIO mode to be used: +1) A multiport card is detected. PIO mode will always be used. (8 port cards +do not support DMA). +2) The DMA channel is set to an invalid value (anything other than 1 or 3). +3) The DMA buffer/channel could not be allocated. The port will revert to PIO +mode until it is reopened. +4) Less than a specified number of bytes need to be transferred to/from the +FIFOs. PIO mode will be used for that transfer only. +5) A port needs to do a DMA transfer and another port is already using the +DMA channel. PIO mode will be used for that transfer only. + +Since the Hayes ESP seems to conflict with other cards (notably sound cards) +when using DMA, DMA is turned off by default. To use DMA, it must be turned +on explicitly, either with the "dma=" option described below or with +setserial. A multiport card can be forced into DMA mode by using setserial; +however, most multiport cards don't support DMA. + +The latest version of setserial allows the enhanced configuration of the ESP +card to be viewed and modified. +*** + +This package contains the files needed to compile a module to support the Hayes +ESP card. The drivers are basically a modified version of the serial drivers. + +Features: + +- Uses the enhanced mode of the ESP card, allowing a wider range of + interrupts and features than compatibility mode +- Uses DMA and 16 bit PIO mode to transfer data to and from the ESP's FIFOs, + reducing CPU load +- Supports primary and secondary ports + + +If the driver is compiled as a module, the IRQs to use can be specified by +using the irq= option. The format is: + +irq=[0x100],[0x140],[0x180],[0x200],[0x240],[0x280],[0x300],[0x380] + +The address in brackets is the base address of the card. The IRQ of +nonexistent cards can be set to 0. If an IRQ of a card that does exist is set +to 0, the driver will attempt to guess at the correct IRQ. For example, to set +the IRQ of the card at address 0x300 to 12, the insmod command would be: + +insmod esp irq=0,0,0,0,0,0,12,0 + +The custom divisor can be set by using the divisor= option. The format is the +same as for the irq= option. Each divisor value is a series of hex digits, +with each digit representing the divisor to use for a corresponding port. The +divisor value is constructed RIGHT TO LEFT. Specifying a nonzero divisor value +will automatically set the spd_cust flag. To calculate the divisor to use for +a certain baud rate, divide the port's base baud (generally 921600) by the +desired rate. For example, to set the divisor of the primary port at 0x300 to +4 and the divisor of the secondary port at 0x308 to 8, the insmod command would +be: + +insmod esp divisor=0,0,0,0,0,0,0x84,0 + +The dma= option can be used to set the DMA channel. The channel can be either +1 or 3. Specifying any other value will force the driver to use PIO mode. +For example, to set the DMA channel to 3, the insmod command would be: + +insmod esp dma=3 + +The rx_trigger= and tx_trigger= options can be used to set the FIFO trigger +levels. They specify when the ESP card should send an interrupt. Larger +values will decrease the number of interrupts; however, a value too high may +result in data loss. Valid values are 1 through 1023, with 768 being the +default. For example, to set the receive trigger level to 512 bytes and the +transmit trigger level to 700 bytes, the insmod command would be: + +insmod esp rx_trigger=512 tx_trigger=700 + +The flow_off= and flow_on= options can be used to set the hardware flow off/ +flow on levels. The flow on level must be lower than the flow off level, and +the flow off level should be higher than rx_trigger. Valid values are 1 +through 1023, with 1016 being the default flow off level and 944 being the +default flow on level. For example, to set the flow off level to 1000 bytes +and the flow on level to 935 bytes, the insmod command would be: + +insmod esp flow_off=1000 flow_on=935 + +The rx_timeout= option can be used to set the receive timeout value. This +value indicates how long after receiving the last character that the ESP card +should wait before signalling an interrupt. Valid values are 0 though 255, +with 128 being the default. A value too high will increase latency, and a +value too low will cause unnecessary interrupts. For example, to set the +receive timeout to 255, the insmod command would be: + +insmod esp rx_timeout=255 + +The pio_threshold= option sets the threshold (in number of characters) for +using PIO mode instead of DMA mode. For example, if this value is 32, +transfers of 32 bytes or less will always use PIO mode. + +insmod esp pio_threshold=32 + +Multiple options can be listed on the insmod command line by separating each +option with a space. For example: + +insmod esp dma=3 trigger=512 + +The esp module can be automatically loaded when needed. To cause this to +happen, add the following lines to /etc/modprobe.conf (replacing the last line +with options for your configuration): + +alias char-major-57 esp +alias char-major-58 esp +options esp irq=0,0,0,0,0,0,3,0 divisor=0,0,0,0,0,0,0x4,0 + +You may also need to run 'depmod -a'. + +Devices must be created manually. To create the devices, note the output from +the module after it is inserted. The output will appear in the location where +kernel messages usually appear (usually /var/adm/messages). Create two devices +for each 'tty' mentioned, one with major of 57 and the other with major of 58. +The minor number should be the same as the tty number reported. The commands +would be (replace ? with the tty number): + +mknod /dev/ttyP? c 57 ? +mknod /dev/cup? c 58 ? + +For example, if the following line appears: + +Oct 24 18:17:23 techno kernel: ttyP8 at 0x0140 (irq = 3) is an ESP primary port + +...two devices should be created: + +mknod /dev/ttyP8 c 57 8 +mknod /dev/cup8 c 58 8 + +You may need to set the permissions on the devices: + +chmod 666 /dev/ttyP* +chmod 666 /dev/cup* + +The ESP module and the serial module should not conflict (they can be used at +the same time). After the ESP module has been loaded the ports on the ESP card +will no longer be accessible by the serial driver. + +If I/O errors are experienced when accessing the port, check for IRQ and DMA +conflicts ('cat /proc/interrupts' and 'cat /proc/dma' for a list of IRQs and +DMAs currently in use). + +Enjoy! +Andrew J. Robinson <arobinso@nyx.net> |