MCP2515 with kernel 4.16

QiayuanLiao

I have used a standard 4.4 kernel with UP Board HAT support patch and an RT patch Ubuntu-RT-UP-Board. I am trying to use mcp2515 for CAN Bus, I write a driver which work well.

#include <linux/init.h>
#include <linux/module.h>
#include <linux/spi/spi.h>
#include <linux/can/platform/mcp251x.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>

int busnum = 2;
int chip_select = 0;
int gpio_int = 25;

module_param(busnum, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
MODULE_PARM_DESC(busnum, "busnum of spi bus to use");

module_param(gpio_int, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
MODULE_PARM_DESC(gpio_int, "linux gpio number of INT gpio");

module_param(chip_select, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
MODULE_PARM_DESC(chip_select, "spi chip select");

int gpio_requested = 0;

struct spi_device * dev1;
static struct mcp251x_platform_data mcp251x_info = {
  .oscillator_frequency = 16000000,
};

static struct spi_board_info spi_device_info = {
  .modalias = "mcp2515",
  .platform_data = & mcp251x_info,
  .irq = -1,
  .max_speed_hz = 10 * 1000 * 1000,
};

static int __init mcp2515_init(void) {
  int ret;
  struct spi_master * master;

  printk("mcp2515: init\n");

  ret = gpio_request(gpio_int, "sysfs");

  if (ret) {
    printk("mcp2515: could not request gpio %d\n", gpio_int);
    gpio_free(gpio_int);
    return ret;
  }
  gpio_requested = 1;

  gpio_direction_input(gpio_int);

  ret = gpio_to_irq(gpio_int);
  printk("mcp2515: irq for pin %d is %d\n", gpio_int, ret);
  spi_device_info.irq = ret;
  spi_device_info.bus_num = busnum;
  spi_device_info.chip_select = chip_select;

  master = spi_busnum_to_master(spi_device_info.bus_num);
  if (!master) {
    printk("mcp2515: MASTER not found.\n");
    ret = -ENODEV;
    goto error_postgpio;
  }

  // create a new slave device, given the master and device info
  dev1 = spi_new_device(master, & spi_device_info);

  if (!dev1) {
    printk("mcp2515: FAILED to create slave.\n");
    ret = -ENODEV;
    goto error_postgpio;
  }

  printk("mcp2515: device created!\n");

  return 0;

  error_postgpio:
    gpio_free(gpio_int);
  return ret;
}

static void __exit mcp2515_exit(void) {
  printk("mcp2515: exit\n");

  if (dev1) {
    spi_unregister_device(dev1);
  }
  if (gpio_requested)
    gpio_free(gpio_int);
}

module_init(mcp2515_init);
module_exit(mcp2515_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("One");
MODULE_DESCRIPTION("MCP2515");

But I want to use UP Squared, and I try the kernel 4.15/4.16 with the driver I write on UP Board, but when I load the MCP2515 withsudo modprobe mcp2515 and sudo ip link set can0 type can bitrate 1000000 everything since ok. But when I type sudo ip link set up can0 and enter, the whole system crash. I got (sorry for the camera view, the system is crash):


So anybody has a similar work and suggestion?

DCleri

Hi @QiayuanLiao

If you are using UP Squared and you are interfacing the device via SPI, then you need to check the following: https://wiki.up-community.org/Pinout_UP2#SPI_Ports

SPI ports number is changing and you might need to add the ACPI override in order to use your driver and maybe other changes too.

Also there is an official driver for that in the linux kernel, have you tried if that works?

https://github.com/torvalds/linux/blob/master/drivers/net/can/spi/mcp251x.c

rreignier

@DCleri said:
Also there is an official driver for that in the linux kernel, have you tried if that works?

https://github.com/torvalds/linux/blob/master/drivers/net/can/spi/mcp251x.c

@QiayuanLiao is actually using this driver, see: https://forum.up-community.org/discussion/96/canbus-hat-support

But because this driver uses Device Tree to get parameters and there is no progress on ACPI SSDT as mentioned here , we still have to write a (small) kernel module to use it.

QiayuanLiao

Yes, I write a small kernel module that I have posted above. It works on kernel 4.4 with UP Board (Not UP Squared!), when I test on kernel 4.16, the issue above happened.

DCleri

That solution was reported to work for UP Squared and latest kernel.

@QiayuanLiao have you tried what has been provided on that topic?

@BenSpex said:
So if anyone else hast the problem I have found the solution:
From @WereCatf
https://forum.up-community.org/discussion/2415/cant-get-fbtft-device-working-ubilinux

That's because you have used the spi-enable.zip from the Wiki -- it reserves those chip-select pins and that's why they can't be used by device-drivers. You have to delete the file /lib/firmware/acpi-upgrades/spidev1.0.aml if you want to use cs0, or /lib/firmware/acpi-upgrades/spidev1.1.aml if you want to use cs1, and run:
sudo update-initramfs -u -k all
This updates the initramfs, removing the claim on the SPI-bus, so you have to reboot afterwards.

QiayuanLiao

I am trying kernel 4.9 now. It works on both UP Board and UP Squared after I patch the meta-up-board pyro, and LEDs, SPI, GPIO, PWM all work. But when I use full Fully Preemptible Kernel (RT), the system will freeze easily.

QiayuanLiao

The problem seems became "real-time 4.9 kernel freeze on UP Board". I have met the same problem when using ubilinux (now ubuntu 16.04 or 18.04)

DCleri

It's good news that it works with a normal kernel (not realtime).

Have you tried with Sumo on Kernel 4.14?

Are you following the suggestions from WereCatf?

QiayuanLiao

@DCleri said:
It's good news that it works with a normal kernel (not realtime).

Have you tried with Sumo on Kernel 4.14?

Are you following the suggestions from WereCatf?

I didn't follow the suggestions from WereCatf. I mean I am working on UP Board, not UP Squared now.
My workflow is as follow:
1. kernel 4.4 with RT, HAT, and MCP2515. All work on UP Board, but HAT unable to work on UP Squared.
2. kernel 4.15 with RT, HAT, and MCP2515. HAT work on UP Board, but when using MCP2515, the whole system freeze. So I didn't try on UP Squared
3. kernel 4.9 with RT, HAT, and MCP2515. RT patch leads to system freeze on UP Board. So I didn't try on UP Squared