Dear Wolfgang Wegner, In message <20100423205938.gu20...@leila.ping.de> you wrote: > This patch adds bootcount for Freescale MCF5445x. Two registers of > eDMA transfer control descriptors (TCD[1]) are used because these > are unused by linux kernel (freescale LTIB linux-2.6.25) and were > tested to keep their contents across resets. > TCD[1] is currently unused by the linux drivers, so using its registers > should be safe as long as no non-standard driver is loaded. > > Signed-off-by: Wolfgang Wegner <w.weg...@astro-kom.de> > --- > I implemented and tested this bootcount on a custom MCF54455 board. > According to the data sheet, the internal SRAM is not supposed to be > useful for data storage across resets. There is no explicit statement > concerning the TCD registers, but in tests on our board the values > did always survive reset. > v2: updated comment > v3: moved updated comment to the right place :-)
Did you??? > arch/m68k/cpu/mcf5445x/cpu.c | 29 +++++++++++++++++++++++++++++ > arch/m68k/include/asm/immap_5445x.h | 1 + > 2 files changed, 30 insertions(+), 0 deletions(-) > > diff --git a/arch/m68k/cpu/mcf5445x/cpu.c b/arch/m68k/cpu/mcf5445x/cpu.c > index 6238bc0..70007c1 100644 > --- a/arch/m68k/cpu/mcf5445x/cpu.c > +++ b/arch/m68k/cpu/mcf5445x/cpu.c > @@ -110,3 +110,32 @@ int cpu_eth_init(bd_t *bis) > return mcffec_initialize(bis); > } > #endif > + > +#ifdef CONFIG_BOOTCOUNT_LIMIT > +/* > + * We use transfer descriptor registers as a persistent storage > + * across resets. This was tested on a MCF54455. > + * Neither U-Boot nor the stock LTIB kernel seem to use > + * TCD[1], so it should be safe at least until application > + * start. > + */ This still reads the same... Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de The biggest difference between time and space is that you can't reuse time. - Merrick Furst _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
