[U-Boot] i.MX35PDK: Starting U-Boot from serial NOR-Flash

[Hornung, Michael]

Dear list,

I have an i.MX35PDK (mx35_3stack) with one U-Boot running within the NAND flash and one U-Boot running within the parallel NOR flash. 

I am now trying to get another one running in a serial NOR flash (S25FL064K) I soldered to the CSPI1 lines with CSPI1_SS1 as chip select line. 

Then I changed the bootstrap switches as follows:

BOOT_MODE[1:0]:	00 	Internal boot
BT_MEM_CTL[1:0]:	11 	Expansion device (... , serial ROM)
BT_BUS_WIDTH:	1 	3-byte address SPI device (serial Flash)
BT_MEM_TYPE[1:0]	11 	Serial ROM via SPI

According to my oscilloscope (SPI decoder included), the hardware setup behaves as it should do. The processor clocks, it activates the SS1 line, 
it sends read commands (0x03) following an address and the serial flash sends answers with bytes matching the u-boot.bin file.

I tried the following to build the u-boot binary:

1. 	$ make mx35pdk
	Then I burned u-boot.bin to the serial flash starting at address 0x00

2. 	See 1. but burning the u-boot.bin file to the serial flash starting at address 0x400 (doc/README.imximage)

3.	$ make mx35pdk
	$ cp board/freescale/mx51evk/imximage.cfg board/freescale/mx35pdk/
          	$ ./tools/mkimage -n ./board/freescale/mx35pdk/imximage.cfg -T imximage -e 0xA0000000 -d u-boot.bin u-boot.imx
	Then I burned u-boot.imx to the serial flash starting at address 0x00

4.	See 3. but burning the u-boot.imx file to the serial flash starting at address 0x400 (doc/README.imximage)
 
As you might guess, none of the above attempts works. I get no serial output from U-Boot.

Has anyone a short description how to compile U-Boot in order to run from serial NOR flash?

Thank you very much in advance.

With best regards


Michael Hornung