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Adaptive Body Biasing (ABB) modulates transistor bias voltages dynamically in order to optimize switching speed versus leakage. Adaptive Body-Bias ldos are present for some voltage domains starting with OMAP3630. There are three modes of operation: * Bypass - the default, it just follows the vdd voltage * Foward Body-Bias - applies voltage bias to increase transistor performance at the cost of power. Used to operate safely at high OPPs. * Reverse Body-Bias - applies voltage bias to decrease leakage and save power. Used to save power at lower OPPs. Signed-off-by: Andrii Tseglytskyi <andrii.tseglytskyi@ti.com> Acked-by: Nishanth Menon <nm@ti.com>
67 lines
2 KiB
C
67 lines
2 KiB
C
/*
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*
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* Adaptive Body Bias programming sequence for OMAP5 family
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*
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* (C) Copyright 2013
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* Texas Instruments, <www.ti.com>
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*
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* Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#include <common.h>
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#include <asm/omap_common.h>
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#include <asm/io.h>
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/*
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* Setup LDOVBB for OMAP5.
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* On OMAP5+ some ABB settings are fused. They are handled
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* in the following way:
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*
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* 1. corresponding EFUSE register contains ABB enable bit
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* and VSET value
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* 2. If ABB enable bit is set to 1, than ABB should be
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* enabled, otherwise ABB should be disabled
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* 3. If ABB is enabled, than VSET value should be copied
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* to corresponding MUX control register
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*/
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s8 abb_setup_ldovbb(u32 fuse, u32 ldovbb)
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{
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u32 vset;
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/*
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* ABB parameters must be properly fused
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* otherwise ABB should be disabled
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*/
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vset = readl(fuse);
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if (!(vset & OMAP5_ABB_FUSE_ENABLE_MASK))
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return -1;
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/* prepare VSET value for LDOVBB mux register */
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vset &= OMAP5_ABB_FUSE_VSET_MASK;
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vset >>= ffs(OMAP5_ABB_FUSE_VSET_MASK) - 1;
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vset <<= ffs(OMAP5_ABB_LDOVBBMPU_VSET_OUT_MASK) - 1;
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vset |= OMAP5_ABB_LDOVBBMPU_MUX_CTRL_MASK;
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/* setup LDOVBB using fused value */
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clrsetbits_le32(ldovbb, OMAP5_ABB_LDOVBBMPU_VSET_OUT_MASK, vset);
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return 0;
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}
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