Subject: Re: mpc5200b configure nand driver via dts

From: Wolfgang Grandegger <[email-masked]>
Date: Wed, 14 Jan 2009 10:05:43 +0100

[email-masked] wrote:
>>> On Mon, Jan 12, 2009 at 2:07 AM,  <[email-masked]>
>> wrote:
>>>> hello,
>>>>
>>>> I have some problems with an mpc5200b based board. It's nearly
>> compatible to
>>>> the lite5200b board.
>>>> I connected an samsung k9k8g08u0a nand flash via the lpb bus. This
>> works
>>>> fine with an self written nand driver.
>>>> Now I try to use the standard nand driver from linux and configure
>> it via
>>>> the dts file. But this doesn't work and I get
>>>> the following output:
>>>>
>>>>   nand@1,0 {  //cs1
>>>>    compatible = "samsung, k9k8g08u08", "cfi-flash";
>>>                                           ^^^^^^^^^
>>>
>>> NAND Flash is not a CFI flash device.  The cfi-flash driver won't
>> work with it.
> Which compatible mode whould you choose ?

There is no mode/driver ready to use. You need to implement a MTD NAND
driver supporting the compatible "fsl,lpb-nand", similar to:

http://lxr.linux.no/linux+v2.6.28/arch/powerpc/boot/dts/mpc836x_rdk.dts#L390

>>>> Now my questions are:
>>>>  Is there any error in the dts configuration?
>>>>  Is it principle posible to configure a nand flash via the dts
>> file (in
>>>> combination with mpc5200b)?
>>> It is possible to *describe* the NAND flash via the dts file.  The
>> dts
>>> file doesn't configure anything.  It just describes the hardware
>>> layout so that you can write or bind the appropriate driver to the
>>> device.  I don't know if a device tree binding has been defined for
>>> NAND flash yet.
>> I find 3 MTD NAND drivers with OF bindings in
>> linux-2.6/drivers/mtd/nand
>>
>>   $ grep -l of_device *.c
>>   fsl_elbc_nand.c
>>   fsl_upm.c
>>   pasemi_nand.c
>>
>> The bindings for the FSL UPM are described in
>> http://lxr.linux.no/linux
> v2.6.28/Documentation/powerpc/dts-bindings/fsl/upm-nand.txt.
>> Something similar is needed for his board (NAND connected to lpb) as
>> well.
> 
> Am I wrong or is the MTD_NAND_FSL_UPM only useable with PPC_83xx or
> PPC_85xx?

That's right. The MPC5200 does *not* have an UPM.

>>>>  I read in some forums that the nand flash must be activated in
>> the u-boot
>>>> before it can be configured via dts.
>>> You definitely need to set up the CS line for the NAND before using
>> it
>>> in Linux.  Typically this is done in U-Boot, but in a pinch it can
>> be
>>> done in the platform support code (arch/powerpc/platforms/52xx/*)
>> Yep, and also the R/B pin should be handled somehow, preferably using
>> the OF GPIO interface.
> 
> I set the upper named points in the u-boot, now. 
> 
> +++ b/board/ybox/ybox.c
> @@ -282,6 +282,32 @@ void flash_preinit(void)
>          * executing in flash.
>          */
>         *(vu_long *)MPC5XXX_BOOTCS_CFG &= ~0x1; /* clear RO */
> +
> +
> +       /* Configure PSC3_6 as ChipSelect for NAND Flash chip
> +        set PSC3_6 pin as GPIO output */
> +        *(vu_long *)MPC5XXX_GPIO_ENABLE |= 0x00001000; /*enable GPIO*/
> +        *(vu_long *)MPC5XXX_GPIO_ODE &=  ~0x00001000; /* no OpenDrain
> */
> +        *(vu_long *)MPC5XXX_GPIO_DIR |= 0x00001000; /* Direction =
> output */
> +        *(vu_long *)MPC5XXX_GPIO_DATA_O |= 0x00001000; /* Set CS to 1
> (low active)*/
> +       /* NAND config*/
> +       /* Configure IRQ_0 as input for Ready/Busy pin*/
> +        *(vu_long *)MPC5XXX_ICTL_EXT &= ~0x00000800; /*disable IRQ_0
> interrupt */
> +        *(vu_long *)MPC5XXX_ICTL_EXT |= 0x00C00000; /*low active */
> +       *(vu_long *)MPC5XXX_ADDECR &= ~0x00020000; /*disable cs1 */
> +
> +        /* Configure the ChipSelect 1 on LocalPlusBus for data
> transfers
> +        there is a config chip select function allready, but beter do
> all for nand
> +        at one place */
> +        /*CS1 start / end address*/
> +        *(vu_long *)MPC5XXX_CS1_START = 0x00007000;
> +        *(vu_long *)MPC5XXX_CS1_STOP = (0x00007000 + 0x100);
> +        /*CS1 master enable */
> +        *(vu_long *)MPC5XXX_CS_CTRL = 0x01;
> +        *(vu_long *)MPC5XXX_CS1_CFG = 0x0f0f1800;
> +       *(vu_long *)MPC5XXX_ADDECR |= ~0x00020000; /*enable cs1 */
> +        /*enable PIN as ChipSelect*/
> +        *(vu_long *)MPC5XXX_GPS_PORT_CONFIG |= 0x80000000;
>  }

You need a dedicated MTD NAND driver for U-Boot as well.

Wolfgang.