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