diff options
Diffstat (limited to 'u-boot/doc/README.at91-soc')
| -rw-r--r-- | u-boot/doc/README.at91-soc | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/u-boot/doc/README.at91-soc b/u-boot/doc/README.at91-soc new file mode 100644 index 0000000..425fc58 --- /dev/null +++ b/u-boot/doc/README.at91-soc @@ -0,0 +1,64 @@ + New C structure AT91 SoC access +================================= + +The goal +-------- + +Currently the at91 arch uses hundreds of address defines and special +at91_xxxx_write/read functions to access the SOC. +The u-boot project perferred method is to access memory mapped hw +regisister via a c structure. + +e.g. old + + *AT91C_PIOA_IDR = AT91_PMX_AA_TWD | AT91_PMX_AA_TWCK; + *AT91C_PIOC_PUDR = AT91_PMX_AA_TWD | AT91_PMX_AA_TWCK; + *AT91C_PIOC_PER = AT91_PMX_AA_TWD | AT91_PMX_AA_TWCK; + *AT91C_PIOC_OER = AT91_PMX_AA_TWD | AT91_PMX_AA_TWCK; + *AT91C_PIOC_PIO = AT91_PMX_AA_TWD | AT91_PMX_AA_TWCK; + + at91_sys_write(AT91_RSTC_CR, + AT91_RSTC_KEY | AT91_RSTC_PROCRST | AT91_RSTC_PERRST); + +e.g new + pin = AT91_PMX_AA_TWD | AT91_PMX_AA_TWCK; + writel(pin, &pio->pioa.idr); + writel(pin, &pio->pioa.pudr); + writel(pin, &pio->pioa.per); + writel(pin, &pio->pioa.oer); + writel(pin, &pio->pioa.sodr); + + writel(AT91_RSTC_KEY | AT91_RSTC_CR_PROCRST | + AT91_RSTC_CR_PERRST, &rstc->cr); + +The method for updating +------------------------ + +1. add's the temporary CONFIG_AT91_LEGACY to all at91 board configs +2. Display a compile time warning, if the board has not been converted +3. add new structures for SoC access +4. Convert arch, driver and boards file to new SoC +5. remove legacy code, if all boards and drives are ready + + Join AT91 and AT91RM9200 SoC +============================== + +Approximately 95 percent of AT91 and AT91RM9200 SoC parts are the same. +So, we should use the chance, to join both archs togetter. + +To do this follow step needed: + +1. change Makefile + @$(MKCONFIG) $(@:_config=) arm arm920t board vendor at91rm9200 + to + @$(MKCONFIG) $(@:_config=) arm arm920t board vendor at91 +2. remove CONFIG_AT91_LEGACY in board config +3. convert boards file to new SoC access +4. convert or change drivers + +To support the joining process, a new SoC dir (at91) has been adding to +arm920t arch directory. This directory contains files like at91rm9200 dir, but +uses the new c structure Soc access. The advantage of this is, we don't merge +old Soc access code and new code while the board are not converted. +Finally we can delete the whole at91rm9200 dir, if all board support the +new AT91-SoC access. |