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authorJens Scharsig <js_at_ng@scharsoft.de>2010-02-03 22:45:42 +0100
committerTom Rix <Tom.Rix@windriver.com>2010-02-12 12:31:54 -0600
commit425de62d40f84524b90e776b141b060cd438a9fe (patch)
tree2ec5d36153c265b896d1e87f3dab07471353a372 /doc/README.at91-soc
parent3a4e43921d2599453ea87c623099e5f347c9e54a (diff)
downloadu-boot-linaro-stable-425de62d40f84524b90e776b141b060cd438a9fe.tar.gz
add new CONFIG_AT91_LEGACY
* add's the new temporary CONFIG_AT91_LEGACY to all board configs This will need for backward compatiblity, while change the SoC access to c structures. If CONFIG_AT91_LEGACY is defined, the deprecated SoC is used. Signed-off-by: Jens Scharsig <js_at_ng@scharsoft.de>
Diffstat (limited to 'doc/README.at91-soc')
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diff --git a/doc/README.at91-soc b/doc/README.at91-soc
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+ 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