Memory mapped device access in Linux

tsik · 10-31-2006, 04:11 PM

I am trying to access (read/write) a memory mapped device in Linux using a C program.

Currently I am using the following piece of code in order to write data to the device.

tsuAddress[0]=0xb0000; //The address of the device is 0xb0000
tsuFileDescriptor[0] = open("/dev/mem", O_RDWR) ;

lseek(tsuFileDescriptor[0],tsuAddress[0], SEEK_SET);
write(tsuFileDescriptor[0],&dataToWrite,4);

Although data are finally sent to the device, they are NOT sent IMMEDIATELY after the write() function has completed (as I understand, the Operating System makes some buffering prior to sending the data to the device).

To be more specific, what I want is for the data to be sent to the memory mapped device IMMEDIATELY after the write() function executes.

Thanking you in advance, TSIK
www.tsik.eu

studioj · 10-31-2006, 09:26 PM

make some realtime FIFO files in the dev directory
they get a much higher scheduling priority
rtf_create()
rtf_put()
rtf_get()