Serial device access with qemu!

[Jeferson Luiz Rodrigues Souza]

Dear Joel,

On Tue, Nov 23, 2010 at 2:21 PM, Joel Sherrill <joel.sherrill at oarcorp.com>wrote:

> On 11/23/2010 02:50 AM, Jeferson Luiz Rodrigues Souza wrote:
>
>> Hi everyone,
>>
>> I am trying to access a serial port in RTEMS 4.9.4 using a pc586 bsp.
>> However, when I execute the application using qemu the code cannot open the
>> device, and the perror() function presents the following message: "No such
>> file or directory". It seems that RTEMS did not initialize a properly driver
>> to handle serial device. Is it right?
>>
>> The qemu command line is:
>>
>> sudo qemu -serial "/dev/ttyS0" -fda floppy.img -boot a
>>
>> I made a search in this list and I found references about serial port
>> access but nothing to help in my case. Could anyone help me or point me some
>> documentation about serial port access in RTEMS?
>>
>> The code used in the test is presented below. I do not have some
>> experience with RTEMS and I do not know the source of this problem.
>>
>>  The /dev/ttyS0 above is the host serial port.  The -serial says
> attach attach the serial port COM1 on the target simulator
> PC to the specified device.  So you are attaching the virtual
> COM1 to the real serial port on the host /dev/ttyS0. Is that
> what you intend to do?
>
> FWIW COM1 --> /dev/ttyS1
> COM2 --> /dev/ttyS2
>
> on the RTEMS target.
>
>
I need to read some data from a device connected in the host serial port
(e.g. /dev/ttyS0) inside an application running in RTEMS with qemu.  So, is
my source code correct? or Do I need some extra configuration?

Where is the name of serial devices in RTEMS defined? I tried use the open()
function as follows:

 int serial_fp = open("/dev/ttyS0",O_RDONLY);
or
 int serial_fp = open("/dev/ttyS1",O_RDONLY);
or
 int serial_fp = open("COM1",O_RDONLY);

and got the same message when I checked the serial_fp value and print the
error message using perror() function: "No such file or directory"

Thanks to reply,

Best regards,
Jeferson.


> --joel
>
>  Thanks,
>> jefecomp.
>>
>>
>> #include <signal.h>
>> #include <stdlib.h>
>> #include <stdio.h>
>> #include <pthread.h>
>> #include <uart.h>
>> #include <termios.h>
>> #include<sched.h>
>> #include <bsp.h>
>> #include <fcntl.h>
>> #include <sys/types.h>
>> #include <sys/stat.h>
>>
>> #define CONFIGURE_INIT
>> #include <rtems.h>
>>
>>
>> void *POSIX_Init();
>>
>> #define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
>> #define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
>> #define CONFIGURE_APPLICATIONS_NEEDS_RTC_DRIVER
>> #define CONFIGURE_MICROSECONDS_PER_TICK 1000
>>
>> #define CONFIGURE_MAXIMUM_POSIX_THREADS 10
>> #define CONFIGURE_MAXIMUM_POSIX_CONDITION_VARIABLES 10
>> #define CONFIGURE_MAXIMUM_POSIX_MUTEXES 10
>> #define CONFIGURE_MAXIMUM_POSIX_SEMAPHORES 10
>> #define CONFIGURE_MAXIMUM_POSIX_TIMERS 10
>> #define CONFIGURE_MAXIMUM_POSIX_QUEUED_SIGNALS 40
>> #define CONFIGURE_MAXIMUM_POSIX_MESSAGE_QUEUES 10
>> #define CONFIGURE_POSIX_INIT_THREAD_TABLE
>> #define CONFIGURE_LIBIO_MAXIMUM_FILE_DESCRIPTORS 5
>> #define CONFIGURE_NUMBER_OF_TERMIOS_PORTS 3
>> #include<rtems/confdefs.h>
>>
>> void *POSIX_Init()
>> {
>>    printf("Serial Port Test!!!\n");
>>
>>    char buffer[255];
>>    int bytesRead;
>>    int serial_fp = open("/dev/ttyS0",O_RDONLY);
>>
>>    printf("SERIAL_FP = %i\n",serial_fp);
>>
>>    if(serial_fp < 0)
>>    {
>>        printf("FAILURE TO OPEN SERIAL PORT\n");
>>        perror(serial_fp);
>>        exit(-1);
>>    }
>>
>>    //write(serial_fp,buffer,strlen(buffer)+1);
>>    bytesRead = read(serial_fp, buffer, 255);
>>
>>
>>    if(bytesRead < 0)
>>    {
>>        printf("Problems in the read of Serial Port");
>>        close(serial_fp);
>>        exit(1);
>>    }
>>    else
>>        buffer[bytesRead] = 0;
>>
>>
>>    printf(buffer);
>>
>>    close(serial_fp);
>>    exit(0);
>> }
>>
>
>
> --
> Joel Sherrill, Ph.D.             Director of Research&  Development
> joel.sherrill at OARcorp.com        On-Line Applications Research
> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
>   Support Available             (256) 722-9985
>
>
>
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