The purpose is to do DMA transfer betwee Processing System (PS) and Programmable Logic (PL) for a ZYNQ 7000 board. I am trying to use Userspace Input Outut (UIO) framework. I have a UIO device in my ZYNQ board. I am using mmap to access the UIO device. From my application I can write to the device but cannot read, what can cause such behaviour?
I am given below only the lines that is relavant, ommiting all other lines. I am not sure the other lines are relavant or not. Other lines are unchanged. In the first case, the write command return err=4 which is correct but in the second case, "read", nothing is returned?
fd_uio = open("/dev/uio0",O_RDWR);mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_uio, (off_t) 0);err=write(fd_uio, (void *)&pending, sizeof(int));fd_uio = open("/dev/uio0",O_RDWR);mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_uio, (off_t) 0);err=read(fd_uio, (void *)&pending, sizeof(int))The below is edited code in case we can use memcpy() instead of read?
fd_uio = open("/dev/uio0",O_RDWR);fd_mem = open("/dev/mem",O_RDWR);fromPtr=mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_uio, (off_t) 0);destPtr=mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_mem, (off_t) 0);memcpy( destPtr, fromPtr, size);EDIT:
uint32_t Val =89;void *regs = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_uio, (off_t) 0); *((volatile uint32_t *)(regs))=Val; uint32_t dma_status=*((volatile uint32_t *)(regs+4)); printf("Value of errno: %d\n", errno); printf("dma_status %" PRIu32 "\n\r",dma_status);In the above code I was expecting the dma_status to be 89 but I do not get 89. I get 0 if (regs+4) or I get 65563 if I do regs.
The following may help. I have tried to use reserve memory by adding the following lines in system-user.dtsi file:
reserved-memory{ #address-cells=<1>; #size-cells =<1>; ranges; dma_reserved:buffer@0{ compatible="shared-dma-pool"; no-map; reg=<0x30000000 0x1000000>; }; }; dma_proxy@0 { compatible ="xlnx,dma_proxy"; dmas = <&axi_dma_0 1>; dma-names = "dma0"; memory-region = <&dma_reserved>; };But when I try to check if the reserved memory is there or not in the board, I get the following.
two:/home/petalinux# dmesg | grep eserveOF: fdt: Reserved memory: failed to reserve memory for node 'buffer@0': base 0x00000005, size 0 MiBOF: fdt: Reserved memory: failed to reserve memory for node 'buffer@0': base 0x00000000, size 512 MiBcma: Reserved 16 MiB at 0x3f000000Memory: 998020K/1048576K available (7168K kernel code, 243K rwdata, 1904K rodata, 1024K init, 118K bss, 34172K reserved, 16384K cma-reserved, 245760K highmem)hw-breakpoint: found 5 (+1 reserved) breakpoint and 1 watchpoint registers.Further edit:
The problem may be that when I type dmesg | grep eserve I get 0F: fdt: Reserved memory: failed to reserve memory for node 'buffer@0': base 0x00000005, size 0 Mib
and
0F: fdt: Reserved memory: failed to reserve memory for node 'buffer@0: base 0x00000000, size 512 Mib and
cma:Reserved 16 MiB at 0x3f000000The output of cat /proc/iomem is below
three:~$ sudo cat /proc/iomem 00000000-2fffffff : System RAM 00008000-00afffff : Kernel code 00c00000-00c5c727 : Kernel data31000000-3fffffff : System RAMe0001000-e0001fff : xuartpse000a000-e000afff : e000a000.gpio gpio@e000a000e000b000-e000bfff : e000b000.ethernet ethernet@e000b000e000d000-e000dfff : e000d000.spi spi@e000d000e0100000-e0100fff : e0100000.mmc mmc@e0100000f8003000-f8003fff : dma-controller@f8003000 f8003000-f8003fff : f8003000.dma-controller dma-controller@f8003000f8005000-f8005fff : f8005000.watchdog watchdog@f8005000f8007000-f80070ff : f8007000.devcfg devcfg@f8007000f8007100-f800711f : f8007100.adc adc@f8007100f8801000-f8801fff : etb@f8801000f8803000-f8803fff : tpiu@f8803000f8804000-f8804fff : funnel@f8804000f889c000-f889cfff : ptm@f889c000f889d000-f889dfff : ptm@f889d000fffc0000-fffcffff : fffc0000.sram sram@fffc0000