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>

4 files changed, 206 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/omap-common/Makefile b/arch/arm/cpu/armv7/omap-common/Makefile
index 55e82ba369..c4b9809ad0 100644
--- a/arch/arm/cpu/armv7/omap-common/Makefile
+++ b/arch/arm/cpu/armv7/omap-common/Makefile
@@ -34,6 +34,7 @@ COBJS	+= hwinit-common.o
 COBJS	+= clocks-common.o
 COBJS	+= emif-common.o
 COBJS	+= vc.o
+COBJS	+= abb.o
 endif
 
 ifneq ($(CONFIG_AM33XX)$(CONFIG_OMAP44XX)$(CONFIG_OMAP54XX)$(CONFIG_TI814X),)
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 0000000000..87d1fb82eb
--- /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);
+}
diff --git a/arch/arm/cpu/armv7/omap5/Makefile b/arch/arm/cpu/armv7/omap5/Makefile
index ce00e2c3c5..6ff8dbb4eb 100644
--- a/arch/arm/cpu/armv7/omap5/Makefile
+++ b/arch/arm/cpu/armv7/omap5/Makefile
@@ -30,6 +30,7 @@ COBJS	+= emif.o
 COBJS	+= sdram.o
 COBJS	+= prcm-regs.o
 COBJS	+= hw_data.o
+COBJS	+= abb.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS) $(SOBJS))
diff --git a/arch/arm/cpu/armv7/omap5/abb.c b/arch/arm/cpu/armv7/omap5/abb.c
new file mode 100644
index 0000000000..92470becc0
--- /dev/null
+++ b/arch/arm/cpu/armv7/omap5/abb.c
@@ -0,0 +1,67 @@
+/*
+ *
+ * Adaptive Body Bias programming sequence for OMAP5 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>
+
+/*
+ * Setup LDOVBB for OMAP5.
+ * On OMAP5+ some ABB settings are fused. They are handled
+ * in the following way:
+ *
+ * 1. corresponding EFUSE register contains ABB enable bit
+ *    and VSET value
+ * 2. If ABB enable bit is set to 1, than ABB should be
+ *    enabled, otherwise ABB should be disabled
+ * 3. If ABB is enabled, than VSET value should be copied
+ *    to corresponding MUX control register
+ */
+s8 abb_setup_ldovbb(u32 fuse, u32 ldovbb)
+{
+	u32 vset;
+
+	/*
+	 * ABB parameters must be properly fused
+	 * otherwise ABB should be disabled
+	 */
+	vset = readl(fuse);
+	if (!(vset & OMAP5_ABB_FUSE_ENABLE_MASK))
+		return -1;
+
+	/* prepare VSET value for LDOVBB mux register */
+	vset &= OMAP5_ABB_FUSE_VSET_MASK;
+	vset >>= ffs(OMAP5_ABB_FUSE_VSET_MASK) - 1;
+	vset <<= ffs(OMAP5_ABB_LDOVBBMPU_VSET_OUT_MASK) - 1;
+	vset |= OMAP5_ABB_LDOVBBMPU_MUX_CTRL_MASK;
+
+	/* setup LDOVBB using fused value */
+	clrsetbits_le32(ldovbb,  OMAP5_ABB_LDOVBBMPU_VSET_OUT_MASK, vset);
+
+	return 0;
+}