u-boot/doc/README.davinci
Sekhar Nori 4f6fc15b42 DA850 EVM: passing maximum clock rate information to kernel
The TI DA850/OMAP-L138/AM18x EVM can be populated with devices
having different maximum allowed CPU clock rating.

The maximum clock the chip can support can only be determined from
the label on the package (not software readable).

Introduce a method to pass the maximum allowed clock rate information
to kernel using ATAG_REVISION. The kernel uses this information to
determine the maximum cpu clock rate reachable using cpufreq.

Note that U-Boot itself does not set the CPU clock rate. The CPU
clock is setup by a primary bootloader ("UBL"). The rate setup by
UBL could be different from the maximum clock rate supported by the
device.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>
2010-11-19 16:29:11 -05:00

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Summary
=======
This README is about U-Boot support for TI's ARM 926EJS based family of SoCs.
These SOCs are used for cameras, video security and surveillance, DVR's, etc.
DaVinci SOC's comprise of DM644x, DM646x, DM35x and DM36x series of SOC's
Additionally there are some SOCs meant for the audio market which though have
an OMAP part number are very similar to the DaVinci series of SOC's
Additionally, some family members contain a TI DSP and/or graphics
co processors along with a host of other peripherals.
Currently the following boards are supported:
* TI DaVinci DM644x EVM
* TI DaVinci DM646x EVM
* TI DaVinci DM355 EVM
* TI DaVinci DM365 EVM
* TI DA830 EVM
* TI DA850 EVM
* DM355 based Leopard board
* DM644x based schmoogie board
* DM644x based sffsdr board
* DM644x based sonata board
Build
=====
* TI DaVinci DM644x EVM:
make davinci_dvevm_config
make
* TI DaVinci DM646x EVM:
make davinci_dm6467evm_config
make
* TI DaVinci DM355 EVM:
make davinci_dm355evm_config
make
* TI DaVinci DM365 EVM:
make davinci_dm365evm_config
make
* TI DA830 EVM:
make da830evm_config
make
* TI DA850 EVM:
make da850evm_config
make
* DM355 based Leopard board:
make davinci_dm355leopard_config
make
* DM644x based schmoogie board:
make davinci_schmoogie_config
make
* DM644x based sffsdr board:
make davinci_sffsdr_config
make
* DM644x based sonata board:
make davinci_sonata_config
make
Bootloaders
===============
The DaVinci SOC's use 2 bootloaders. The low level initialization
is done by a UBL(user boot loader). The UBL is written to a NAND/NOR/SPI flash
by a programmer. During initial bootup, the ROM Bootloader reads the UBL
from a storage device and loads it into the IRAM. The UBL then loads the U-Boot
into the RAM.
The programmers and UBL are always released as part of any standard TI
software release associated with an SOC.
Environment Variables
=====================
The DA850 EVM allows the user to specify the maximum cpu clock allowed by the
silicon, in Hz, via an environment variable "maxcpuclk".
The maximum clock rate allowed depends on the silicon populated on the EVM.
Please make sure you understand the restrictions placed on this clock in the
device specific datasheet before setting up this variable. This information is
passed to the Linux kernel using the ATAG_REVISION atag.
If "maxcpuclk" is not defined, the configuration CONFIG_DA850_EVM_MAX_CPU_CLK
is used to obtain this information.
Links
=====
1) TI DaVinci DM355 EVM:
http://focus.ti.com/docs/prod/folders/print/tms320dm355.html
http://www.spectrumdigital.com/product_info.php?cPath=103&products_id=203&osCsid=c499af6087317f11b3da19b4e8f1af32
2) TI DaVinci DM365 EVM:
http://focus.ti.com/docs/prod/folders/print/tms320dm365.html?247SEM=
http://support.spectrumdigital.com/boards/evmdm365/revc/
3) DaVinci DM355 based leopard board
http://designsomething.org/leopardboard/default.aspx
http://www.spectrumdigital.com/product_info.php?cPath=103&products_id=192&osCsid=67c20335668ffc57cb35727106eb24b1
4) TI DaVinci DM6467 EVM:
http://focus.ti.com/docs/prod/folders/print/tms320dm6467.html
http://support.spectrumdigital.com/boards/evmdm6467/revf/
5) TI DaVinci DM6446 EVM:
http://focus.ti.com/docs/prod/folders/print/tms320dm6446.html
http://www.spectrumdigital.com/product_info.php?cPath=103&products_id=222
6) TI DA830 EVM
http://focus.ti.com/apps/docs/gencontent.tsp?appId=1&contentId=52385
http://www.spectrumdigital.com/product_info.php?cPath=37&products_id=214
7) TI DA850 EVM
http://focus.ti.com/docs/prod/folders/print/omap-l138.html
http://www.logicpd.com/products/development-kits/zoom-omap-l138-evm-development-kit