Re: 8250 memory mapped UART

[Gailu Singh]

I checked coreboot where in the memory it is mapped and it seems to be on PCIE. Relevant code from coreboot. So I am hopeful that patch will work.

---------

uintptr_t uart_platform_base(int idx)

{

u8      *pcie;

u32      tmp;

idx  = idx & 3;

pcie = (u8 *)PCIE_MMIO(0, PCH_DEV_SLOT_UART, idx, 0);

tmp  = read32 (pcie + PCI_BASE_ADDRESS_0);

if (tmp == 0xFFFFFFFF) {

/* the device might be hidden */

return LPSS_UART_BASE_ADDRESS;

} else {

return (uintptr_t) (tmp & 0xFFFFFFF0);

}

}  

---------

 I applied the patches and run make clean followed by make but build failed as follows

------------------------

cat syminfo.lst | sort | gawk -f ./genmoddep.awk > moddep.lst || (rm -f moddep.lst; exit 1)

grub_ns8250_pci_mmio_init in serial is not defined

make[3]: *** [moddep.lst] Error 1

------------------------

On Wed, Mar 1, 2017 at 3:27 PM, Gailu Singh <address@hidden> wrote:

Sorry for typo. I meant 8250 instead of 8050 in last email

On Wed, Mar 1, 2017 at 3:21 PM, Gailu Singh <address@hidden> wrote:

My board is Intel Oxbohill CRB (Apollo lake). On my board UART are not connected to PCI. 

I am using grub2 payload loaded by coreboot. UART works fine in coreboot by using memory mapped 8050 driver (https://github.com/coreboot/coreboot/blob/master/src/drivers/uart/uart8250mem.c), however when grub2 is loaded it refuses to recognize UART.

On Wed, Mar 1, 2017 at 3:08 PM, Matthias Lange <address@hiddenm> wrote:

Hi,

On 03/01/2017 08:00 AM, Andrei Borzenkov wrote:
> please test patches from Matthias Lange
>
> https://lists.gnu.org/archive/html/grub-devel/2017-02/msg00104.html
>
>
> On Wed, Mar 1, 2017 at 9:15 AM, Gailu Singh <address@hidden> wrote:
>> Hi Experts,
>>
>> I am using GRUB2 on intel apollo lake board. This board does not have IO
>> mapped uart instead it has 8250 memory mapped UART.

Could you share some details about the board?

>> GRUB2 does not recognize memory mapped uart and gives error ("serial port
>> COM0 not found). There is a 8250 memory mapped driver available in coreboot.
>> Is it possible to port that driver to Grub2?

My patch set adds support for 8250 MMIO PCI cards. Is the UART on your
board connected via PCI?

Best,
Matthias.