[U-Boot] guys, can you see some init code for davinci's chipselect bit width driving DM9000A?

yaojin liu lanmanck at gmail.com
Mon Jul 19 16:51:33 CEST 2010


thanks,you are right, it really init the chip through UBL.
BUT, there is also one question:
DM9000a 's driver has 8 bit accessing function:

#define CONFIG_DM9000_BASE    0x04000000
#define DM9000_IO            CONFIG_DM9000_BASE
#define DM9000_DATA        (CONFIG_DM9000_BASE+2) // (BA1,it's the 16bit
least significant bit (effective)  )
#define DM9000_outb(d,r) ( *(volatile u8 *)r = d )
#define DM9000_inb(r) (*(volatile u8 *)r)
static u8 DM9000_ior(int reg)
{
    DM9000_outb(reg, DM9000_IO);
    return DM9000_inb(DM9000_DATA);
}

/*
   Write a byte to I/O port
*/
static void DM9000_iow(int reg, u8 value)
{
    DM9000_outb(reg, DM9000_IO);
    DM9000_outb(value, DM9000_DATA);
}
and the davinci's chipselect space is 16bit. when accessing it as 8bit ,the
last bit(may be A-2 ?) will be effective, but the least significant bit(BA1)
will not be effective, am i wrong? how does it work?

2010/7/19 Stefano Babic <sbabic at denx.de>

> yaojin liu wrote:
> > hi:
> > dm9000a works as 16bit bus width. however, i have not seen any init code
> for
> > the dm355's chipselect.
> > and by default ,the cs1 is 8bit bus width at reset. how doew it work?
>
> I think the setup is done by the UBL provided by TI. U-boot is a 3-rd
> stage bootloader for DM355. The RBL (Rom Bootloader) loads the UBL from
> storage, that sets up the required peripherals (RAM / AEMIF), and then
> loads u-boot.
>
> u-boot does not set the a2cr register in the AEMIF interface, but the
> UBL has already configured it for 16-bit access.
>
> Best regards,
> Stefano Babic
>
> --
> =====================================================================
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: +49-8142-66989-0 Fax: +49-8142-66989-80  Email: office at denx.de
> =====================================================================
>


More information about the U-Boot mailing list