104 lines
4.1 KiB
Markdown
104 lines
4.1 KiB
Markdown
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# Overview
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The [cifX/M.2](https://www.hilscher.com/products/pc-cards-for-industrial-ethernet-fieldbus/m2) card is a netX90 based multi function PCIe device. It provides a SPI interface for accessing the netX90 as well as multiple GPIOs. GPIO at offset 7 can optionally be used as an interrrupt source (DIRQ) for the cifX driver.
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The driver consists of the kernel modules ax99100-pci-spi and the optional ax99100-pci-gpio.
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### ax99100-pci-spi.ko:
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The module abstracts the PCIe to SPI transfers via the Linux spidev interface.
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The module supports interrupt and DMA based tranfers.
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Accesses less than 8 byte are executed via fifo mode and may be slower than DMA.
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### ax99100-pci-gpio.ko (optional):
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### NOTE: Currently the build is disabled by default, since the current version is not compatible with the latest linux version.
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The module delivers interrupts generated by the changes, by the netX, of the DPMs handshake cells (DIRQ pin) via a GPIO pin.
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If not loaded the cifX driver will poll the DPMs handshake cells.
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<pre>
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</pre>
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### Build the driver modules:
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To build the kernel mode driver just enter this folder and run make.
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```
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make
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```
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Copy the driver modules into the desired kernel library folder which they are compiled for.
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```
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sudo make modules_install
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```
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Update the module dependencies in the modules.dep file.
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```
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sudo depmod
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```
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### Loading ax99100-pci-spi:
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By default the module will create the SPI device to access the netX90 on the cifX/M.2 card with SPI mode set to 3 and the maximum speed of 40Mhz.
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In this case the SPI interface will be /dev/spidev[x].0.
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NOTE: Speed and mode can be easily configured by the user space application via the cifX driver SPI plugin or the drivers interface.
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For a detailed explanaition of the SPI plugin configuration refer to the Linux cifX Driver Documentation.
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In case the SPI driver need to be changed or the maximum speed should be limited the module provides parameter arrays for configuration purposes.
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It is possible to register up to 3 SPI slave devices.
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The module parameter 0-2 will configure the SPI interfaces of the SPI slaves at chip select 0-2.
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Module parameter 0 will setup and grant access to the netX90 on the cifX/M.2 card.
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Module parameters are:
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- modalias[0..2]=<driver>
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Optional, if not specified spidev is selected.
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In common Linux environment choose "spidev" as the driver which handles the SPI acccess. The device will appear than
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as /dev/spidev[x].0
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NOTE: Starting with kernel 5.x "spidev" was removed. You will need to use one of the following list
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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/spi/spidev.c?h=v5.15.90#n687
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(e.g. spi-petra)
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- mode[0..2]=[0..3]
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Optional, if not specified mode 3 is choosen.
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- max_speed_hz[0..2]=<freq>
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Optional, if not specified the maximum 40Mhz is configured.
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Speed configuration during runtime via the cifX SPI plugin or the drivers interface (e.g. spidev driver via SPI_IOC_[RD/WR]_MAX_SPEED_HZ) can
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not exceed the configured value.
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Example: Configure the SPI interface (at chip-select 0) for accessing the netX90 based cifX/M.2 card with mode 3 and a maximum speed of 25Mhz.
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```
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modprobe ax99100-pci-spi modalias0=spidev mode0=3 max_speed_hz0=25000000
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```
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To enable the auto creation of spidev device at boot time, a configuration file must be created as follow.
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```
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echo "options ax99100-pci-spi modalias0=spidev" > /etc/modprobe.d/cifx-m2.conf
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```
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### Loading ax99100-pci-gpio (optional):
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NOTE: The current implementation may not be compatible with the latest kernel version and is therefore disabled by default.
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To enable interrupt support for the DPMs handshake cells:
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```
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modprobe ax99100-pci-gpio
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```
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Loading the module will create a gpio chip module in the sysfs directory (/sys/class/gpio/).
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After the exporting the GPIO (offset 7) the following GPIO sysfs configuration is required:
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```
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direction = "in"
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edge = "rising"
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active_low = "1"
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```
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Add the path to the "value" file in the SPI plugin configuration (e.g. /opt/cifx/plugins/netx-spm/config0):
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```
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Irq=/sys/class/gpio/gpio[xxx]/value
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```
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Enable irq for the device (e.g. /opt/cifx/FW/device.conf):
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```
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irq=yes
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```
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