Making a Phone Call with Phase Change Memory Justin Treon Embedded Linux Conference Session W-130-C April 15, 2008

Page 2 Copyright © 2008 Numonyx B.V.

Objective

•Explain Techniques I Use to Modify This Phone

•Phase Change Memory

– Changes required for PCM• Bit-Alterable Writing


Project Goals

•PCM Demonstration Platform– Realistic Device

• Make a phone call

– Utilize Bit Alterable Features

•The Problem– Original Phone: 48 MB of RAM and 1.8V V18 NOR Flash

• x32P ball-out

– Modified Phone: 32 MB of RAM and 3.3V PCM• SDRAM: x16D ball-out

• PCM: EZBGA ball-out


Modifying the Phone


Modifying the Phone•Communicating with the Phone•Changing the System Memory


JTag and UART

•Depopulated Phone– Memory Stack

– Applications Processor


JTag and UART



•Manufactured a Debug Board– Cut phones apart to make

connectors

Special thanks to Daniel Willmann


JTag and UART



•Manufactured a Debug Board– Cut phones apart to make

connectors

•Debugging Tools– Intel® XDB Debugger

– Albatross BDI 2000

• Ethernet Capable


Boot Log

•Dmesg through BusyBox– Not very useful if it is not booting

•Boot Log Over UART Disabled– Boot Log disabled to decrease boot time

•Boot Log to Display– Kept the display in TEXT mode

• Commenting out: vt_cons[conp->vc_num]->vc_mode = KD_GRAPHICS;


Enable Serial Port

•Hardware pins available, but not enabled

•Enabled the STUART in the Bootloader

•Modified the CRAMFS Root Image to Provide a Login Prompt– Adding the following to /etc/inittab:

T0:23:respawn:/sbin/getty -L ttyS2 115200 vt100

Special thanks to Daniel Willmann


EZBGA to x32P

• Converting from x16D to x32P

• From EZBGA x16D– Converting from 1.8V to 3.3V


Going from 48MB to 32MB

•Original Phone had 48MB of SDRAM•Modified Phone has 32 MB of SDRAM•Changes to the Boot Loader Memory Mapapboot/src/blob/HW_init.c@@ -165,7 +165,7 @@ {0xA0000000, 0x00F00000, 0x0a}, // SDRAM Bank 0, 15M, B=0, C=1 {0xA0F00000, 0x00100000, 0x02}, // SDRAM Bank 0, 1M, B=0, C=0 {0xA1000000, 0x01000000, 0x0a}, // SDRAM Bank 0, 16M, B=0, C=1- {0xAC000000, 0x01000000, 0x0a}, // SDRAM Bank 3, 16M, B=0, C=0+ // Change to the map to only use 32MB of SDRAM {0, 0, 0x0} // end };


Modifying the Kernel Memory Usage

•Changes to the Kernel’s Use of Memory BanksKernel/arch/arm/mm/init.c

@@ -443,6 +443,8 @@

unsigned int bootmap_pages, bootmap_pfn, map_pg;

int node, initrd_node;

+mi->nr_banks = 2; /* Hack to use 32MB of SDRAM */

+

bootmap_pages = find_memend_and_nodes(mi, np);

bootmap_pfn = find_bootmap_pfn(0, mi, bootmap_pages);

initrd_node = check_initrd(mi);


Enabling PCM


Enabling PCM•PCM Technology•How to Integrate Drivers•Driver Feed Back


Phase Change Memory

• Made From The Same Material as Re-Writable CDs

NORNOR

NANDNAND RAMRAM

ExecutionXIP

FastWrites

No Erase,Bit Alterability

NVM

RAMPCM


PCM System Benefits

•Software for Flash Memories can be Simplified– Erase/write in background, block management, garbage collection, etc..

•Overwrite Capability Allows Simplification of Software Stack– Flash Translation Layer is no longer needed

– Improves system level performance

File and Chunk Size

MB/sFAT on PCM

(FAT + FTL) on Flash

Defrag ON> x5


New Commands

•Backwards Compatible– Traditional erase and write commands are backwards compatible

•No Need to Erase Blocks with PCM– New Commands

• Bit-Alterable Write One Word

• Bit-Alterable Buffer Write


Updating the CFI tables

•Original phone used Common Flash Interface 1.3

•Our PCM used CFI version 1.5@@ -326,6 +347,10 @@

goto need_more;

nb_parts = extp->extra[extra_size - 1];

+ /* skip the sizeof(partregion) field in CFI 1.4 */

+ if (extp->MinorVersion >= '4')

+ extra_size += 2;

+ for (i = 0; i < nb_parts; i++) {

struct cfi_intelext_regioninfo *rinfo;

rinfo = (struct cfi_intelext_regioninfo *)&extp->e


Adding Bit-Alterable Support

•For a MontaVista 3.0, Based on Linux Kernel 2.4.20– Changes to:

• drivers/mtd/chips/cfi_cmdset_0001.c

• drivers/mtd/mtdblock.c

• drivers/mtd/mtdpart.h

• include/linux/mtd/mtd.h

•The Majority of Changes to cfi_cmdset_0001.c– Adding:

•static int cfi_intelext_overwrite_words(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);

•static int cfi_intelext_overwrite_buffers(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);


Enabling a Desktop Filing System

•Minor Changes to drives/mtd/mtdblock.cstatic int mtdblock_writesect(struct mtd_blktrans_dev *dev,

unsigned long block, char *buf){

struct mtdblk_dev *mtdblk = mtdblks[dev->devnum];struct mtd_info *mtd = mtdblk->mtd;size_t retlen;int ret;

ret = (*(mtd->overwrite))(mtd, block<<9, 512, &retlen, buf);if (ret)

return ret;if (retlen != 512) {

printk("mtdblock: EIO error\n");return -EIO;

}return 0;

}


Acknowledgements

•Abatron BDI 2000 – www.abatron.ch – High speed debugger developers, gdb compatible

•BusyBox – www.busybox.net – Compact suite of tools

•InetD daemon – www.e2mod.com – author unknown

•OpenEZX – www.openezx.org – Organization devoted make EZX phones truly Open phones



Dead Phones

•8 Phones used for project– 2 Work

•Malfunctioning Phones– 1 Used for Signal Tracing

– 1 Damage to Baseband

– 2 Lost Pads During Rework

– 1 Damaged Power Circuitry

– 1 Reasons Unknown


Key Learnings

•Start With At Least 4 Phones

•Fasten Down All Boards and Cables

•Add or Make Connectors– Saves pads

– Makes it portable


System Assembly

Documents

Making a Phone Call with Phase Change Memory Justin Treon Embedded Linux Conference Session W-130-C April 15, 2008