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 <andrii.tseglytskyi@ti.com>
Acked-by: Nishanth Menon <nm@ti.com>
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, <www.ti.com>
+ *
+ * Andrii Tseglytskyi <andrii.tseglytskyi@ti.com>
+ *
+ * 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 <common.h>
+#include <asm/omap_common.h>
+#include <asm/io.h>
+#include <asm/arch/sys_proto.h>
+
+__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);
+}