RE: i.MX35 3-stack use only 128MB RAM

[Boaz Ben-David <boaz.bd@wellsense-tech.com>]

Hi,

This is the procedure for modifying Redboot to support 256MB of RAM in Redboot, you can adapt it to barebox:

How to extend RAM for Linux on MX35PDK
=======================================

Tested on: redboot_200910, MX35PDK green board, MX35 TO2, DDR2, SDK1.5

The current redboot images enable just half of the physically available DDR2 memory (128MB on MX35PDK).
This is due to the fact that redboot is only enabling SDCS0 (BANK0) and not SDCS1. 
It seems that there was a little bug in redboot which has prevented the enablement of SDCS1 and so
nobody has tried this again. Physically the bank1 is working properly on MX35PDK CPU module.

Step0
=====

Check memory size of existing redboot on your MX35PDK

under redboot check memory on SDCS1 which is mapped physically to 0x90000000.
You may also use 0x08000000 which is the first virtual address on SDCS1.
Note in redboot, the virtual address 0x80000000 is mapped to physical address 0x80000000 non cashable.
Virtual Address 0x0 is mapped to physical address 0x80000000 cashable.
The virtual address 0x90000000 is not in the MMU table. That is why we receive a "illegal memory address" error message.
 This is not a memory exception because no memory transaction has  taken place.
See also below...


RedBoot> dump -b 0x90000000
90000000: ** command abort - illegal memory access?
RedBoot> dump -b 0x08000000
08000000: ** command abort - illegal memory access?
RedBoot> dump -b 0x07ffff00
07FFFF00: FF FF FF FF FF FF FF FF  FF FF FF FF FF FF FF FF  |................|
07FFFF10: FF FF FF FF FF FF FF FF  FF FF FF FF FF FF FF FF  |................|

After booting linux use command "free":

root@freescale ~$ free
              total         used         free       shared      buffers
  Mem:       126140         9920       116220            0            0
 Swap:            0            0            0
Total:       126140         9920       116220

You have about 128MB free memory. But not 256MB.


Step 1
======

We will edit and recompile redboot. For this you may untar the redboot_200910.tgz archive in the linux BSP source
on your linux host.
Unpack redboot and configure the build process as described in 
redboot_200910/doc/redboot_mx35.pdf Chapter 6

You should be able to run successfully:

            ecosconfig new mx35_3stack redboot
            ecosconfig import $ECOS_REPOSITORY/hal/arm/mx35/3stack/current/misc/redboot_ROMRAM.ecm
            ecosconfig tree
            make

Step 2
======

We will know edit some redboot source files as discribed below. Look at the comment
"// by michael for 256MB".


~/redboot_200910/src/ecos/packages/hal/arm/mx35/3stack/current/include/pkgconf/mlt_arm_board_romram.h

#ifndef __ASSEMBLER__
#include <cyg/infra/cyg_type.h>
#include <stddef.h>

#endif
#define CYGMEM_REGION_ram (0x00000000)
#define CYGMEM_REGION_ram_SIZE (0x0FF00000) // by michael for 256MB
#define CYGMEM_REGION_ram_ATTR (CYGMEM_REGION_ATTR_R | CYGMEM_REGION_ATTR_W)
#define CYGMEM_REGION_rom (0x87F00000)
#define CYGMEM_REGION_rom_SIZE (0x100000)
#define CYGMEM_REGION_rom_ATTR (CYGMEM_REGION_ATTR_R)
#ifndef __ASSEMBLER__
extern char CYG_LABEL_NAME (__heap1) [];
#endif
#define CYGMEM_SECTION_heap1 (CYG_LABEL_NAME (__heap1))
#define CYGMEM_SECTION_heap1_SIZE (CYGMEM_REGION_ram_SIZE - (size_t) CYG_LABEL_NAME (__heap1))


~/redboot_200910/src/ecos/packages/hal/arm/mx35/3stack/current/include/hal_plaform_setup.h line 712:

       ldr r0, ESDCTL_BASE_W
/* deleted by michael
        mov r3, #0x2000
        str r3, [r0, #0x0]
        ldr r2, ROM_VER_ADDR_W
        ldr r4, [r2]
        cmp r4, #0x1
        streq r3, [r0, #0x8]
*/
 mov r12, #0x00
 mov r2, #0x0 // DDR2
 mov r1, #RAM_BANK0_BASE
 bl setup_sdram_bank
 cmp r3, #0x0
3: bne 3b  // loop forever if bank0 is not OK

/* do not repeat with mDDR settings. We know we have DDR2 (r2=0)
 cmp r3, #0x0
 orreq r12, r12, #1
 eorne r2, r2, #0x1
 blne setup_sdram_bank
*/
#if 1 // do the same for bank1
 /* CSD1 */
 mov r12, #0x00
 mov r2, #0x0 // DDR2
 mov r1, #RAM_BANK1_BASE
 bl setup_sdram_bank
 cmp r3, #0x0
4: bne 4b  //loop forever if bank1 is not OK


/* do not try with mDDR again for bank1. we know we have DDR2
 beq 1b
 eorne r2, r2, #0x1
 blne setup_sdram_bank
 orr r12, r12, #1
1:
*/
#endif

~/redboot_200910/src/ecos/packages/hal/arm/mx35/3stack/current/include/fsl_board.h

/* MX35 3-Stack SDRAM is from 0x90000000, 64M */
#define SDRAM_BASE_ADDR             CSD0_BASE_ADDR
//#define SDRAM_SIZE                  0x08000000
#define SDRAM_SIZE                  0x10000000   // by michael for 256MB
#define RAM_BANK0_BASE              CSD0_BASE_ADDR
#define RAM_BANK1_BASE              CSD1_BASE_ADDR


~/redboot_200910/src/ecos/packages/hal/arm/mx35/3stack/current/src/board_misc.c

   /*              Actual   Virtual  Size   Attributes                                                    Function  */
    /*              Base     Base     MB     cached?           buffered?        access permissions                 */
    /*              xxx00000 xxx00000                                                                                */
    X_ARM_MMU_SECTION(0x000, 0xF00,   0x1,   ARM_UNCACHEABLE, ARM_UNBUFFERABLE, ARM_ACCESS_PERM_RW_RW); /* ROM */
    X_ARM_MMU_SECTION(0x100, 0x100,   0x1,   ARM_UNCACHEABLE, ARM_UNBUFFERABLE, ARM_ACCESS_PERM_RW_RW); /* iRAM */
    X_ARM_MMU_SECTION(0x300, 0x300,   0x1,   ARM_UNCACHEABLE, ARM_UNBUFFERABLE, ARM_ACCESS_PERM_RW_RW); /* L2CC */
    X_ARM_MMU_SECTION(0x400, 0x400,   0x400, ARM_UNCACHEABLE, ARM_UNBUFFERABLE, ARM_ACCESS_PERM_RW_RW); /* Internal Regsisters upto SDRAM*/
    X_ARM_MMU_SECTION(0x800, 0x000,   0x80,  ARM_CACHEABLE,   ARM_BUFFERABLE,   ARM_ACCESS_PERM_RW_RW); /* SDRAM 0:128M*/
    X_ARM_MMU_SECTION(0x800, 0x800,   0x80,  ARM_CACHEABLE,   ARM_BUFFERABLE,   ARM_ACCESS_PERM_RW_RW); /* SDRAM 0:128M*/
    X_ARM_MMU_SECTION(0x800, 0x880,   0x80,  ARM_UNCACHEABLE, ARM_UNBUFFERABLE, ARM_ACCESS_PERM_RW_RW); /* SDRAM 0:128M*/
    // start by michael for 256MB. Enter new MMU entries for SDCS1
    X_ARM_MMU_SECTION(0x900, 0x080,   0x80,  ARM_CACHEABLE,   ARM_BUFFERABLE,   ARM_ACCESS_PERM_RW_RW); /* SDRAM 1:128M*/
    X_ARM_MMU_SECTION(0x900, 0x900,   0x80,  ARM_CACHEABLE,   ARM_BUFFERABLE,   ARM_ACCESS_PERM_RW_RW); /* SDRAM 1:128M*/
    X_ARM_MMU_SECTION(0x900, 0x980,   0x80,  ARM_CACHEABLE,   ARM_BUFFERABLE,   ARM_ACCESS_PERM_RW_RW); /* SDRAM 1:128M*/
    // end by michael for 256MB
    X_ARM_MMU_SECTION(0xA00, 0xA00,   0x40,  ARM_CACHEABLE,   ARM_BUFFERABLE,   ARM_ACCESS_PERM_RW_RW); /* Flash */
    X_ARM_MMU_SECTION(0xB00, 0xB00,   0x20,  ARM_CACHEABLE,   ARM_BUFFERABLE,   ARM_ACCESS_PERM_RW_RW); /* PSRAM */
    X_ARM_MMU_SECTION(0xB20, 0xB20,   0x1E0, ARM_UNCACHEABLE, ARM_UNBUFFERABLE,ARM_ACCESS_PERM_RW_RW); /* ESDCTL, WEIM, M3IF, EMI, NFC, External I/O */


Step 4
======

rebuild redboot. Now it comes:

The make scripte does not recognize any changes in hal_platform_setup.h file because this file is been used to build
the lib "vectors". This is not in the dependencies of the make script. It is either not removed by "make clean".
You have to remove the vectors.o by hand.

So to properly rebuild redboot you need to:

cd ~/redboot_200910/src/ecos
rm install/lib/vectors.*
make
cp install/bin/redboot.bin ~/shared_folder/redboot_mx35_TO2_256MB.bin # if you have a VMWare and use a shared_folder in ~/shared_folder


Step 5
======

Flash new redboot to MX35PDK using ATK1.6. You do not need to erase the NAND flash. So, you keep the
same fconfig settings. Do not forget the BBT tick!


Step 6
======

Check the new memories:

RedBoot> dump -b 0x90000000
90000000: 00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
90000010: 00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|


root@freescale ~$ free
              total         used         free       shared      buffers
  Mem:       256088        10040       246048            0            0
 Swap:            0            0            0
Total:       256088        10040       246048




Boaz Ben-David
R&D Engineer

Tel: +972.2.6470.700Mob: +972.54.678.1511Email: boaz.bd@wellsense-tech.com
www.themapsystem.com


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________________________________________
From: barebox-bounces@lists.infradead.org [barebox-bounces@lists.infradead.org] On Behalf Of Thomas Mayer [thomas.mayer@telemotive.de]
Sent: Wednesday, April 20, 2011 1:56 PM
To: barebox@lists.infradead.org
Subject: i.MX35 3-stack use only 128MB RAM

Hi,

I read in the freescale documentation "U-Boot for i.MX35 based Designs"
that the i.MX35 3-stack board has 256MB SDRAM, but we can use only 128MB
because the second chip select isn't configured. Depending on the
circuit diagrams I think "CSD1" isn't configured.
I looked already in the datasheet of the cpu, but I couldn't found a
solution for this problem.

Have anybody ever tried to enable this second chip select?


Regards,
Thomas

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