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Microchip mcp251x Linux CAN driver with hardware filtering for the Raspberry PI
craigpeacock/mcp251x
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mcp251x CAN driver with hardware filtering for the Raspberry Pi
Based on patch from:https://support.criticallink.com/redmine/attachments/download/14913/0001-can-mcp251x-Add-ability-to-use-CAN-ID-hw-filter.patch
First download the kernel headers:
$ sudo apt-get install raspberrypi-kernel-headersNow download this repo
$ git clone https://github.com/craigpeacock/mcp251x.gitMake the kernel module:
$ cd mcp251x$ makeIf successful it should display something similar to below and create you a mcp251x.ko file.
make -C /lib/modules/4.19.75+/build M=/home/pi/mcp251x modulesmake[1]: Entering directory '/usr/src/linux-headers-4.19.75+' CC [M] /home/pi/mcp251x/mcp251x.o Building modules, stage 2. MODPOST 1 modules CC /home/pi/mcp251x/mcp251x.mod.o LD [M] /home/pi/mcp251x/mcp251x.komake[1]: Leaving directory '/usr/src/linux-headers-4.19.75+'To test the driver, remove the old one (if loaded) and insert your new module into the kernel using:
$ sudo rmmod mcp251x$ sudo insmod mcp251x.koand check your kernel messages:
$ dmesg | grep -i mcp251x[ 1396.047462] mcp251x: loading out-of-tree module taints kernel.[ 1582.644169] mcp251x spi0.0 can0: MCP2515 successfully initialized.Parameters to specify CAN filters and masks can be sent to the kernel using insmod:
$ sudo insmod mcp251x.ko rxbn_op_mode=1,1 rxbn_filters=0x7E8,0x762 rxbn_mask=0xFFF,0xFFFModinfo can be used to determine parameters:
$ modinfo mcp251x.kofilename: /home/pi/mcp251x/mcp251x.kolicense: GPL v2description: Microchip 251x/25625 CAN driverauthor: Chris Elston <celston@katalix.com>, Christian Pellegrin <chripell@evolware.org>srcversion: 7145C9ABA90EF89DCFA2A61alias: of:N*T*Cmicrochip,mcp25625C*alias: of:N*T*Cmicrochip,mcp25625alias: of:N*T*Cmicrochip,mcp2515C*alias: of:N*T*Cmicrochip,mcp2515alias: of:N*T*Cmicrochip,mcp2510C*alias: of:N*T*Cmicrochip,mcp2510alias: spi:mcp25625alias: spi:mcp2515alias: spi:mcp2510depends: can-devname: mcp251xvermagic: 4.19.75+ mod_unload modversions ARMv6 p2v8parm: mcp251x_enable_dma:Enable SPI DMA. Default: 0 (Off) (int)parm: rxbn_op_mode:0 = (default) MCP2515 hardware filtering will be disabled for receive buffer n (0 or 1). rxb0 controls filters 0 and 1, rxb1 controls filters 2-5 Note there is kernel level filtering, but for high traffic scenarios kernel may not be able to keep up. 1 = use rxbn_mask and rxbn filters, but only accept std CAN ids. 2 = use rxbn_mask and rxbn filters, but only accept ext CAN ids. 3 = use rxbn_mask and rxbn filters, and accept ext or std CAN ids. (array of int)parm: rxbn_mask:Mask used for receive buffer n if rxbn_op_mode is 1, 2 or 3. Bits 10-0 for std ids. Bits 29-11 for ext ids. (array of int)parm: rxbn_filters:Filter used for receive buffer n if rxbn_op_mode is 1, 2 or 3. Bits 10-0 for std ids. Bits 29-11 for ext ids (also need to set bit 30 for ext id filtering). Note that filters 0 and 1 correspond to rxbn_op_mode[0] and rxbn_mask[0], while filters 2-5 corresponds to rxbn_op_mode[1] and rxbn_mask[1] (array of int)When the driver is loaded, you may check the current parameters via the sysfs. e.g.
$ cat /sys/module/mcp251x/parameters/rxbn_op_mode1,1$ cat /sys/module/mcp251x/parameters/rxbn_filters2024,1890,0,0,0,0$ cat /sys/module/mcp251x/parameters/rxbn_mask4095,4095To install the driver:
sudo cp mcp251x.ko /lib/modules/$(uname -r)/kernel/drivers/net/can/spi/Parameters can be passed to the driver using the modprobe daemon. Create a new file /etc/modprobe.d/mcp251x.conf and add the following:
options mcp251x rxbn_op_mode=1,1 rxbn_filters=0x7E8,0x762 rxbn_mask=0xFFF,0xFFF