The On-Chip SRAM Configuration

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1. Introducation
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ADSP21535 has on-chip L1 and L2 SRAM. The L1 SRAM can be 
configured as data and instructure cache. The L1 Scratchpad SRAM 
and L2 SRAM can be used as a general on-chip memory which has 
low latency.

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2. system cache configuration
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Configuration for Eagle board:
memory map	start address        size       cacheable
-------------------------------------------------------
MMR                0xFFC00000         4M         No
L1 Scratchpad      0xFFB00000         4K         No
L2 SRAM            0xF0000000         256K       No
External SDRAM     0x00000000         32M        Yes
PCI Memory	   0xE7000000         16M 	 No
PCI IO/Config	   0xEEF00000	      1M	 No


Configuration for Hawk board:
memory map	start address        size       cacheable
-------------------------------------------------------
MMR                0xFFC00000         4M         No
L1 Scratchpad      0xFFB00000         4K         No
L2 SRAM            0xF0000000         256K       No
External SDRAM     0x00000000         32M        Yes
PCI Memory	   0xE0000000         16M 	 No
PCI IO/Config	   0xEEF00000	      1M	 No


NOTE: 
1) Due to the DCPLB's limitation (there is only 16 DCPLB registers)
   only 16M space is reserved for PCI space.
   If data cache is NOT configured (CONFIG_BLKFIN_DCACHE not defined),
   all of the 128M PCI space can be accessed.

2) The Eagle board's configuration for PCI Memory is different with
   the one of Hawk board.
   The start address of PCI Memory in Eagle board is: 0xE7000000,
   the one of Eagle board is:0xE0000000.

   The reason is that the PCI BIOS (frio_bios32.c) is always trying
   to allocate the PCI Memory for PCI device from high end first.

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3. On-Chip L1 Scratchpad SRAM Management
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To manage the L1 scratchpad SRAM, three interface functions are 
provided.

(1) void l1sram_init(void)
This function is used to initialize the L1 scratchpad memory 
management. It should be called before using the L1 scratchpad 
SRAM.

(2) unsigned long l1sram_alloc(unsigned long size)
This function is used to allocate the L1 scratchpad SRAM.  The 
input argument is allocated memory size.
If memory allocation is successful, this function returns the 
allocated memory start address which is a no-zero value.
If the memory allocated failed, the function returns zero.

(3) int l1sram_free(unsigned long saddr)
This function is used to free the allocated L1 scratchpad SRAM. 
The argument saddr is the start address of the free memory, and 
the saddr should be the return value of the l1sram_alloc() 
function.
If the function is successful, the returned value is zero, 
otherwise, the returned value is -1.

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4. On-Chip L1 Scratchpad SRAM Management
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To manage the L2 SRAM, three interface functions are provided.

(1) void l2sram_init(void)
This function is used to initialize the L2 SRAM memory. It 
should be called before using the L2 SRAM.

(2) unsigned long l2sram_alloc(unsigned long size)
This function is used to allocate the L2 SRAM.  The input 
argument is the allocated memory size.
If the memory allocate successful, this function returns the 
allocated memory start address which is a non-zero value.
If memory allocation fails, the function returns a zero.

(3) int l2sram_free(unsigned long saddr)
This function is used to free the allocated L2 SRAM memory. 
The argument saddr is the start address of the free memory, 
and the saddr should be the return value of the l2sram_alloc() 
function.
If the function is successful the return value is zero, 
otherwise, the return value is -1.

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5. Caution
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