Using a second UART to control a serial device
Pflaum, Clemens
clemens.pflaum at mytum.de
Mon May 4 09:56:26 CEST 2015
Hi,
> How does the 'no access' show? J12 is described as having UART7 so I'd
> assume the UART is there. (UART4 starts on a new page, you have mapped
> that too?)
If I try to read any register like I usally do:
char sc = regs->read<unsigned char>(LCR);
printf("0x0C LCR: %#010x\n", sc);
All i get is 0x00 even if i try writing to it before. I have had the
exact same problem with UART0-3 before manually adjusting the Registers
to their actual offsets or setting the shift parameter of
Io_register_block_mmio to 2. So its actually like I'm looking at/writing
to the wrong places.
I map the memory similar to the serial-drv example only ever one UART at
a time:
#define IRQ_NUM 52 //currently set to UART7, 36 for
UART3
#define UART_BASE 0x01C29C00 //currently set to UART7,
0x01C28C00 for UART3
bool Maestro_server::init()
{
printf("init start\n");
l4_addr_t virt_base = 0;
if (l4io_request_iomem((l4_addr_t)UART_BASE, 0x0400,
L4IO_MEM_NONCACHED, &virt_base))
{
printf("maestro-drv: request io-memory from l4io failed.\n");
return false;
}
printf("maestro-drv: virtual base at:%lx\n", virt_base);
L4::Io_register_block_mmio *regs = new
L4::Io_register_block_mmio(virt_base, 2);
printf("registered regs\n");
_uart = new (malloc(sizeof(L4::Uart_bpi16550)))
L4::Uart_bpi16550((unsigned long) 115200);
printf("malloc for _uart\n");
printf("\n");
if(!(_uart->startup(regs))){
printf("failed to startup uart regs!\n");
}
}
> Hmm, does it work with on Linux, i.e. it's not something
> hardware-related?
I have tested the UARTS with the Bananian linux and they work just fine,
so it cant be hardware-related.
Regards,
Clemens
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