Am trying to validate I2c communication on xilinx zynq zc702 evaluation board in u-boot(as a part of board bring up) with i2c commands but i observed the logs in minicom console saying i2c command not found. Please can i know how to fix this type of issue and how to make the commands work in u-boot
It seems, you didn't enable I2C command in your u-boot configuration and hence it not compile as part of your u-boot.
CONFIG_CMD_I2C=y should be =y, check and recompile your u-boot source
Related
We have an embedded board that has an iMX8M-Plus Processor and Linux v5.4.161. This board has one PCIe bus and that one is connected to an FPGA. When we power up the board, the FPGA is not yet configured, so it acts as if it was not on the PCIe bus.
Once the Linux is fully booted, we configure the FPGA and only after that it starts acting as a PCIe endpoint (device).
At this point, when I run lspci -> it returns nothing.
When I first execute echo "1" > /sys/bus/pci/rescan as suggested here and here and then lspci, I still get nothing.
But if I reboot the linux without reseting the FPGA, it starts being visible in the lspci list. Rebooting the linux is not an option for us. Somehow I need to tell the linux that whatever it's doing at the boot time, please do it again at runtime. But I couldn't find a solution for this so far.
According to the Texas Instrument support forum, they said if the PCIe link is not trained at the boot time, rescan command never works.
At the boot time, while linux loads a pci driver, it tries to establish a PCIe link, I can see that with an oscilloscope, PERST pin is asserted and PCIE_CLK generated for a while and then stops if it can not detect any device. But the rescan command never does that.
Also in the system there is no pcie device to executeecho 1 > $pcidevice/remove in order to make rescan functional. Or there is no device or bus to set power off and on back like echo 0 > /sys/bus/pci/slots/.../power
I also learned that there was a method in old linux times (v2.6) called adding a Fake PCIe Device which physically doesn't exist to solve this problem. For that I took the fakephp.c driver from an old linux repo and ported it to ours. After solving a couple of deprecated function problems, it is compiled for Linux Kernel v5.4. modprobe fakephp worked and driver loaded but somehow I didn't get this fake device in my device list. Here it is mentioned that the fakephp driver was removed from mainstream linux since PCI core has similar functionality, but he never mentioned how.
Short of the story is that, I am stuck here, I need my FPGA to be visible in the lspci list without restarting the linux.
I recommend configuring the FPGA in u-boot to get away from these kinds of problems. Connect up SPI pins to FPGA's config pins & run it in Slave configuration mode.
I am working on a project with SAMA5D3-xplained board with CortexA5 processor and embedded Linux. I would like to send and receive some data via UART during U-Boot is running and before a kernel is loaded to the RAM. I have no idea what I should do. Should I add the second UART to U-Boot device tree source file? Should I change something in a board configuration file? Do you have any ideas on what steps I should take to achieve my goal? Thank you in advance for any help.
EDIT
I would like to use UART from U-Boot C code, not from U-Boot commands. I need to communicate with one of a peripheral device before the kernel is loaded to the RAM.
I assume that you are using the upstream U-Boot from https://source.denx.de/u-boot/u-boot.git.
The device-tree arch/arm/dts/at91-sama5d3_xplained.dts already contains the definitions for six different uarts called serial0 - serial5. serial0 is set in the /chosen node as the standard serial connection. You should be able to see all six devices with the 'dm tree' command.
The currently used UART can be switched by setting the stdin and stdout environment variables.
If you do not want to switch these variables, because you still want output on the default UART you will have to access the device driver. Unfortunately drivers/serial/serial-uclass.c does not yet export functions for this. But _serial_putc(), __serial_getc(), and __serial_tstc() should give you an idea how this is done.
Good day all!
I have an issue in code that I cannot find.
See here
Is it possible to setup GDB to see what the UART is getting in incoming serial data?
Thanks!
I'd suggest you to modify UART driver for Linux kernel and inside of this driver dump the incoming data. The GDB works in user space but you need to do this on the lower level - in UART driver. GDB has no access to registers of the physical device as the UART is.
I'm working on a Cyclone V SOC FPGA from Altera with a double Cortex-A9 processor. The embedded system (linux 4.15.7) is created with Buildroot-2018.02. U-boot is used to load the system i-e FPGA.rbf file, device tree blob and zImage and everything works fine.
I want now to integrate the RBF file to my linux and program the FPGA from Linux. I found several methods and the one I understand is the most common is to use CONFIGFS with a device-tree overlay.
So I changed my device tree to integrate the overlay, the u-boot boot script to disable FPGA load and also the following options in the linux ".config" file with make linux-xconfig :
+CONFIG_OF_OVERLAY=y
+CONFIG_ALTERA_STAPL=y
+CONFIG_CONFIGFS_FS=y
+CONFIG_SAMPLES=y
+CONFIG_SAMPLE_CONFIGFS=m
These options are the state were I am now after several try.
After a make and a reboot, once the kernel is loaded, I enter the following command in the console :
mkdir /config
mount -t configfs none /config
At this state, I'm expecting to see some device tree files in the /config folder but there wasn't any, only one rdma_cm folder :
# ls /config
rdma_cm
I continued my reading on this topic and found that I must enable the CONFIG_OF_CONFIGFS option in my linux kernel.
PROBLEM: This option is not available in my linux kernel. Also, file drivers/of/configfs.c is no here too. I've searched in vain to find how to enable device tree overlay for my kernel version.
How can I configure my kernel to make device-tree available in configfs ?
I had the same problem as you. So I had to make a device driver by myself.
This device driver is tentative and I expect Linux mainline to officially support Device Tree Overlay ConfigFS.
The device driver I made is available at the following URL.
https://github.com/ikwzm/dtbocfg
If you are using Debian, you can build the Debian Package of the device driver with the following URL.
https://github.com/ikwzm/dtbocfg-kmod-dpkg
If you want to try Device Tree Overlay using this device driver, please refer to the following URL.
https://github.com/ikwzm/FPGA-SoC-Linux
https://github.com/ikwzm/FPGA-SoC-Linux-Example-1-DE10-Nano
I am using mcp3021.c file for Microchip MCP3021 IC. My module's init and exit functions are replaced with module_i2c_driver(mcp3021_driver), But I don't see the driver register print in my Kernel log when I ran the code. Can anybody please help me with this ?
First thing which kernel version you are using ? because this macro is introduced in Linux kernel after version 3.3 .
So if your are using kernel version below this you should actually get error while compiling the kernel.
You have verify are few things to make it work,
Ensure that I2C device is properly mounted in hardware.
Confirm that your device is not in reset state.
Ensure that in your device tree you are using the appropriate I2C bus and driver id is properly configured.
Check your kernel configuration(.config) that your driver is enabled.
I2C Probe will be called only if above all conditions are met.