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Kernel Problem on OMAPL137 based custom board

David Allen
Intellectual 685 points
Other Parts Discussed in Thread: DA8XX

Hello everyone.

On my custom board I used UART0 as serial console instead of UART2.

First I edited uboot related files and changed the bootargs: "console=ttyS0,115200n8", the uboot could run right:

U-Boot 1.3.3 (Jul 2 2012 - 16:51:32)

I2C: ready
DRAM: 128 MB
NAND: NAND Manufacturer id: ec
NAND Device id: f1
NAND device: Manufacturer ID: 0xec, Chip ID: 0xf1 (Samsung NAND 128MiB 3,3V 8-bi
t)
128 MiB
In: serial
Out: serial
Err: serial
ARM Clock : 300000000 Hz
Hit any key to stop autoboot: 0
U-Boot >

Second, I edited some kernel related files:

   1, /include/asm/arch-davinci/uncompress.h：

    #define CONSOLE_UART_BASE     DA8XX_UART0_BASE

  2,board-evm.c:

static const short evm_uart0_pins[] = {

      DA8XX_UART0_RXD, DA8XX_UART0_TXD,

      -1

};

When downloading the kernel, the console displayed:

TFTP from server 192.168.1.99; our IP address is 192.168.1.100
Filename 'uImage'.
Load address: 0xc0700000
Loading: #################################################################
#################################################################
#################################################################
#################################################################
#################################################################
###############
done
Bytes transferred = 1737680 (1a83d0 hex)
Automatic boot of image at addr 0xC0700000 ...
## Booting kernel from Legacy Image at c0700000 ...
Image Name: Linux-2.6.18_pro500-da830_omapl1
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 1737616 Bytes = 1.7 MB
Load Address: c0008000
Entry Point: c0008000
Verifying Checksum ... OK
Loading Kernel Image ... OK
OK

Starting kernel ...

Uncompressing Linux.............................................................
....................................................... done, booting the kernel
.
€?

Are there any other configurations in kernel that should be changed to UART0?

  • 0
    Guru 26430 points

    Some other changes.

    arch/arm/mach-davinci/board-da830-evm.c
    static __init void da830_evm_init(void)
    {
    ...
     ret = davinci_cfg_reg_list(da830_uart0_pins);
     if (ret)
       pr_warning("da830_evm_init: uart1 mux setup failed: %d\n", ret);
    ...
    }
    ...
    #ifdef CONFIG_SERIAL_8250_CONSOLE
    static int __init da830_evm_console_init(void)
    {
    ...
      return add_preferred_console("ttyS", 0, "115200");/* Was 2 */
    }
    console_initcall(da830_evm_console_init);
    #endif

    Note that da830_uart0_pins specifies 4 pins.

    arch/arm/mach-davinci/da830.c
    ...
    const short da830_uart0_pins[] __initdata = {
      DA830_NUART0_CTS, DA830_NUART0_RTS, DA830_UART0_RXD, DA830_UART0_TXD,
      -1
    };

    static const struct mux_config da830_pins[] = {
    ...
    MUX_CFG(DA830, NUART0_CTS,   7, 24, 0xf, 2, false)
    MUX_CFG(DA830, NSPI0_ENA,    7, 24, 0xf, 1, false)
    MUX_CFG(DA830, EQEP0A,       7, 24, 0xf, 4, false)
    MUX_CFG(DA830, GPIO5_3,      7, 24, 0xf, 8, false)
    ...
    MUX_CFG(DA830, NUART0_RTS,   7, 28, 0xf, 2, false)
    MUX_CFG(DA830, NSPI0_SCS_0,  7, 28, 0xf, 1, false)
    MUX_CFG(DA830, EQEP0B,       7, 28, 0xf, 4, false)
    MUX_CFG(DA830, GPIO5_4,      7, 28, 0xf, 8, false)
    ...
    MUX_CFG(DA830, UART0_RXD,    8, 12, 0xf, 1, false)
    MUX_CFG(DA830, I2C0_SDA,     8, 12, 0xf, 2, false)
    MUX_CFG(DA830, TM64P0_IN12,  8, 12, 0xf, 4, false)
    MUX_CFG(DA830, GPIO5_8,      8, 12, 0xf, 8, false)
    ...
    MUX_CFG(DA830, UART0_TXD,    8, 16, 0xf, 1, false)
    MUX_CFG(DA830, I2C0_SCL,     8, 16, 0xf, 2, false)
    MUX_CFG(DA830, TM64P0_OUT12, 8, 16, 0xf, 4, false)
    MUX_CFG(DA830, GPIO5_9,      8, 16, 0xf, 8, false)
    ...
    };
    ...

    Note that UART0 might share pins with other peripherals. You will need to disable I2C0, SPI0, etc. to avoid conflict with UART0. You might need to change UART0 to be 2 pin without CTS or RTS. Not quite sure where in the code that would be.

    You might have to modify /etc/inittab to attach the login shell to the desired terminal.