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