From 4d0df9c1e94f32a9695be352fead3167fb5135c7 Mon Sep 17 00:00:00 2001 From: Andrii Tseglytskyi Date: Mon, 20 May 2013 22:42:08 +0000 Subject: OMAP3+: introduce generic ABB support 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 Acked-by: Nishanth Menon --- arch/arm/cpu/armv7/omap-common/abb.c | 137 +++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 arch/arm/cpu/armv7/omap-common/abb.c (limited to 'arch/arm/cpu/armv7/omap-common/abb.c') diff --git a/arch/arm/cpu/armv7/omap-common/abb.c b/arch/arm/cpu/armv7/omap-common/abb.c new file mode 100644 index 0000000..87d1fb8 --- /dev/null +++ b/arch/arm/cpu/armv7/omap-common/abb.c @@ -0,0 +1,137 @@ +/* + * + * Adaptive Body Bias programming sequence for OMAP family + * + * (C) Copyright 2013 + * Texas Instruments, + * + * Andrii Tseglytskyi + * + * See file CREDITS for list of people who contributed to this + * project. + * + * 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 program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +#include +#include +#include +#include + +__weak s8 abb_setup_ldovbb(u32 fuse, u32 ldovbb) +{ + return -1; +} + +static void abb_setup_timings(u32 setup) +{ + u32 sys_rate, sr2_cnt, clk_cycles; + + /* + * SR2_WTCNT_VALUE is the settling time for the ABB ldo after a + * transition and must be programmed with the correct time at boot. + * The value programmed into the register is the number of SYS_CLK + * clock cycles that match a given wall time profiled for the ldo. + * This value depends on: + * settling time of ldo in micro-seconds (varies per OMAP family), + * of clock cycles per SYS_CLK period (varies per OMAP family), + * the SYS_CLK frequency in MHz (varies per board) + * The formula is: + * + * ldo settling time (in micro-seconds) + * SR2_WTCNT_VALUE = ------------------------------------------ + * (# system clock cycles) * (sys_clk period) + * + * Put another way: + * + * SR2_WTCNT_VALUE = settling time / (# SYS_CLK cycles / SYS_CLK rate)) + * + * To avoid dividing by zero multiply both "# clock cycles" and + * "settling time" by 10 such that the final result is the one we want. + */ + + /* calculate SR2_WTCNT_VALUE */ + sys_rate = DIV_ROUND(V_OSCK, 1000000); + clk_cycles = DIV_ROUND(OMAP_ABB_CLOCK_CYCLES * 10, sys_rate); + sr2_cnt = DIV_ROUND(OMAP_ABB_SETTLING_TIME * 10, clk_cycles); + + setbits_le32(setup, + sr2_cnt << (ffs(OMAP_ABB_SETUP_SR2_WTCNT_VALUE_MASK) - 1)); +} + +void abb_setup(u32 fuse, u32 ldovbb, u32 setup, u32 control, + u32 txdone, u32 txdone_mask, u32 opp) +{ + u32 abb_type_mask, opp_sel_mask; + + /* sanity check */ + if (!setup || !control || !txdone) + return; + + /* setup ABB only in case of Fast or Slow OPP */ + switch (opp) { + case OMAP_ABB_FAST_OPP: + abb_type_mask = OMAP_ABB_SETUP_ACTIVE_FBB_SEL_MASK; + opp_sel_mask = OMAP_ABB_CONTROL_FAST_OPP_SEL_MASK; + break; + case OMAP_ABB_SLOW_OPP: + abb_type_mask = OMAP_ABB_SETUP_ACTIVE_RBB_SEL_MASK; + opp_sel_mask = OMAP_ABB_CONTROL_SLOW_OPP_SEL_MASK; + break; + default: + return; + } + + /* + * For some OMAP silicons additional setup for LDOVBB register is + * required. This is determined by data retrieved from corresponding + * OPP EFUSE register. Data, which is retrieved from EFUSE - is + * ABB enable/disable flag and VSET value, which must be copied + * to LDOVBB register. If function call fails - return quietly, + * it means no ABB is required for such silicon. + * + * For silicons, which don't require LDOVBB setup "fuse" and + * "ldovbb" offsets are not defined. ABB will be initialized in + * the common way for them. + */ + if (fuse && ldovbb) { + if (abb_setup_ldovbb(fuse, ldovbb)) + return; + } + + /* clear ABB registers */ + writel(0, setup); + writel(0, control); + + /* configure timings, based on oscillator value */ + abb_setup_timings(setup); + + /* clear pending interrupts before setup */ + setbits_le32(txdone, txdone_mask); + + /* select ABB type */ + setbits_le32(setup, abb_type_mask | OMAP_ABB_SETUP_SR2EN_MASK); + + /* initiate ABB ldo change */ + setbits_le32(control, opp_sel_mask | OMAP_ABB_CONTROL_OPP_CHANGE_MASK); + + /* wait until transition complete */ + if (!wait_on_value(txdone_mask, txdone_mask, (void *)txdone, LDELAY)) + puts("Error: ABB txdone is not set\n"); + + /* clear ABB tranxdone */ + setbits_le32(txdone, txdone_mask); +} -- cgit v1.1