[ECOS] AMD flash driver problem - error reading device ID

[Uwe Kindler <uwe_kindler at web dot de>]

Hello,

currently I'm trying to create a flash driver for our ARM based board. 
The flash driver uses the generic AMD v1 driver package 
(packages/devs/flash/amd/am29xxxxx).
This is the platform definition of my flash driver:

#define CYGNUM_FLASH_INTERLEAVE	(2)
#define CYGNUM_FLASH_WIDTH      (16)
#define CYGNUM_FLASH_SERIES	(1)
#define CYGNUM_FLASH_BASE 	(0x80000000u)

The driver fails reading the device ID from the flash device. I tracked 
the problem down to the function flash_query() in flash_am29xxxxx.inl.

According to the data sheet of the flash, the sequence for reading the 
device ID is:

writing 0xAA to 0x555
writing 0x55 to 0x2AA
writing 0x90 to 0x555

This sequence is represented by the following code in flash_query()

*f_s1 = FLASH_Setup_Code1;
*f_s2 = FLASH_Setup_Code2;
*f_s1 = FLASH_Read_ID;

The problem is, that the calculation of *f_s1 and *f_s2 goes wrong. This 
is the code for calculation in flash_query():

ROM  = (flash_data_t*) CYGNUM_FLASH_BASE;
f_s1 = FLASH_P2V(ROM+FLASH_Setup_Addr1);
f_s2 = FLASH_P2V(ROM+FLASH_Setup_Addr2);

According to my platform definitions I would expect the following values 
for the 3 pointers:

ROM  = 0x80000000
f_s1 = 0x80000555
f_s2 = 0x800002AA

but after calculation the values are:

ROM  = 0x80000000
f_s1 = 0x80001554
f_s2 = 0x80000AA8

I checked the values CYGNUM_FLASH_BASE, FLASH_Setup_Addr1 and 
FLASH_Setup_Addr2 with diag_printf(). They have the follwing values:

CYGNUM_FLASH_BASE = 0x80000000
FLASH_Setup_Addr1 = 0x555
FLASH_Setup_Addr2 = 0xAA8

So it seems that the calculation of the pointers goes wrong.
This is the ARM code produced by the 3 lines of code (compiler option -g2):

mov	r3, #-2147483648 ; 0x80000000
str	r3, [r11, #-20]
ldr	r3, [r11, #-20]
add	r3, r3, #5440	 ; 0x1540
add	r3, r3, #20	 ; 0x14
str	r3, [r11, #-24]
ldr	r3, [r11, #-20]
add	r3, r3, #2720	 ; 0xaa0
add	r3, r3, #8	 ; 0x8
str	r3, [r11, #-28]

I changed the code of the pointer calculation the follwoing way:

ROM  = (flash_data_t*) CYGNUM_FLASH_BASE;
f_s1 = FLASH_P2V((cyg_uint32)ROM+FLASH_Setup_Addr1);
f_s2 = FLASH_P2V((cyg_uint32)ROM+FLASH_Setup_Addr2);

Now I get the expected values. The result is:

ROM  = 0x80000000
f_s1 = 0x80000555
f_s2 = 0x800002AA

And this is the ARM code produced by the new function:

mov	r3, #-2147483648	; 0x80000000
str	r3, [r11, #-20]
ldr	r3, [r11, #-20]
add	r3, r3, #1360	; 0x550
add	r3, r3, #5	; 0x5
str	r3, [r11, #-24]
ldr	r3, [r11, #-20]
add	r3, r3, #680	; 0x2a8
add	r3, r3, #2	; 0x2
str	r3, [r11, #-28]
ldr	r2, [r11, #-24]

Does someone know what is going wrong here? Normally the code in 
flash_query() is used by different ARM platforms so I would not expect a 
problem there. I use the ARM toolchain from the eCos hompage so I would 
not expect a toolchain problem. Is my code change right and should I 
provide a patch or did I something wrong?

Thank you for any help.

Best wishes,

Uwe





 	

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