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rockbox/firmware/target/arm/imx233/emi-imx233.h

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imx233: implement emi frequency scaling (disabled by default) CPU frequency scaling is basically useless without scaling the memory frequency. On the i.MX233, the EMI (external memory interface) and DRAM blocks are responsable for the DDR settings. This commits implements emi frequency scaling. Only some settings are implemented and the timings values only apply to mDDR (extracted from Sigmatel linux port) and have been checked to work on the Fuze+ and Zen X-Fi2/3. This feature is still disabled by default but I expected some battery life savings by boosting higher to 454MHz and unboosting lower to 64MHz. Note that changing the emi frequency is particularly tricky and to avoid writing it entirely in assembly we rely on the compiler to not use the stack except in the prolog and epilog (because it's in dram which is disabled when doing the change) and to put constant pools in iram which should always be true if the compiler isn't completely dumb and since the code itself is put in iram. If this proves to be insufficient, one can always switch the stack to the irq stack since interrupts are disabled during the change. Change-Id: If6ef5357f7ff091130ca1063e48536c6028f23ba
2013-01-10 00:43:08 +00:00
/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2013 by Amaury Pouly
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#ifndef __EMI_IMX233_H__
#define __EMI_IMX233_H__
#include "cpu.h"
#include "system.h"
#include "system-target.h"
imx233: rewrite emi using new register headers Change-Id: Ie893162aac38ea3aaf73b4e84e54be714a5fc33f
2013-06-16 13:30:46 +00:00
#include "regs/regs-emi.h"
#include "regs/regs-dram.h"
imx233: implement emi frequency scaling (disabled by default) CPU frequency scaling is basically useless without scaling the memory frequency. On the i.MX233, the EMI (external memory interface) and DRAM blocks are responsable for the DDR settings. This commits implements emi frequency scaling. Only some settings are implemented and the timings values only apply to mDDR (extracted from Sigmatel linux port) and have been checked to work on the Fuze+ and Zen X-Fi2/3. This feature is still disabled by default but I expected some battery life savings by boosting higher to 454MHz and unboosting lower to 64MHz. Note that changing the emi frequency is particularly tricky and to avoid writing it entirely in assembly we rely on the compiler to not use the stack except in the prolog and epilog (because it's in dram which is disabled when doing the change) and to put constant pools in iram which should always be true if the compiler isn't completely dumb and since the code itself is put in iram. If this proves to be insufficient, one can always switch the stack to the irq stack since interrupts are disabled during the change. Change-Id: If6ef5357f7ff091130ca1063e48536c6028f23ba
2013-01-10 00:43:08 +00:00
imx233: rewrite emi using new register headers Change-Id: Ie893162aac38ea3aaf73b4e84e54be714a5fc33f
2013-06-16 13:30:46 +00:00
#define HW_DRAM_CTLxx(xx) (*(&HW_DRAM_CTL00 + (xx)))
imx233: implement emi frequency scaling (disabled by default) CPU frequency scaling is basically useless without scaling the memory frequency. On the i.MX233, the EMI (external memory interface) and DRAM blocks are responsable for the DDR settings. This commits implements emi frequency scaling. Only some settings are implemented and the timings values only apply to mDDR (extracted from Sigmatel linux port) and have been checked to work on the Fuze+ and Zen X-Fi2/3. This feature is still disabled by default but I expected some battery life savings by boosting higher to 454MHz and unboosting lower to 64MHz. Note that changing the emi frequency is particularly tricky and to avoid writing it entirely in assembly we rely on the compiler to not use the stack except in the prolog and epilog (because it's in dram which is disabled when doing the change) and to put constant pools in iram which should always be true if the compiler isn't completely dumb and since the code itself is put in iram. If this proves to be insufficient, one can always switch the stack to the irq stack since interrupts are disabled during the change. Change-Id: If6ef5357f7ff091130ca1063e48536c6028f23ba
2013-01-10 00:43:08 +00:00
/**
* Absolute maximum EMI speed: 151.58 MHz (mDDR), 130.91 MHz (DDR)
* Intermediate EMI speeds: 130.91 MHz, 120.00 MHz, 64 MHz, 24 MHz
* Absolute minimum CPU speed: 24 MHz */
#define IMX233_EMIFREQ_151_MHz 151580
#define IMX233_EMIFREQ_130_MHz 130910
#define IMX233_EMIFREQ_120_MHz 120000
#define IMX233_EMIFREQ_64_MHz 64000
#define IMX233_EMIFREQ_24_MHz 24000
void imx233_emi_set_frequency(unsigned long freq);
#endif /* __EMI_IMX233_H__ */
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