regulator: Introduce TI Adaptive Body Bias(ABB) on-chip LDO driver

Adaptive Body Biasing (ABB) modulates transistor bias voltages
dynamically in order to optimize switching speed versus leakage.

Texas Instruments' SmartReflex 2 technology provides support for this
power management technique with Forward Body Biasing (FBB) and Reverse
Body Biasing (RBB). These modulate the body voltage of transistor
cells or blocks dynamically to gain performance and reduce leakage.
TI's SmartReflex white paper[1] has further information for usage in
conjunction with other power management techniques.

The application of FBB/RBB technique is determined for each unique
device in some process nodes, whereas, they are mandated on other
process nodes.

In a nutshell, ABB technique is implemented on TI SoC as an on-chip
LDO which has ABB module controlling the bias voltage. However, the
voltage is unique per device. These vary per SoC family and the manner
in which these techniques are used may vary depending on the Operating
Performance Point (OPP) voltage targeted. For example:
OMAP3630/OMAP4430: certain OPPs mandate usage of FBB independent of
devices.
OMAP4460/OMAP4470: certain OPPs mandate usage of FBB, while others may
optionally use FBB or optimization with RBB.
OMAP5: ALL OPPs may optionally use ABB, and ABB biasing voltage is
influenced by vset fused in s/w and requiring s/w override of
default values.

Further, two generations of ABB module are used in various TI SoCs.
They have remained mostly register field compatible, however the
register offset had switched between versions.

We introduce ABB LDO support in the form of a regulator which is
controlled by voltages denoting the desired Operating Performance
Point which is targeted. However, since ABB transition is part of OPP
change sequence, the sequencing required to ensure sane operation
w.r.t OPP change is left to the controlling driver (example: cpufreq
SoC driver) using standard regulator operations.

The driver supports all ABB modes and ability to override ABB LDO vset
control efuse based ABB mode detection etc.

Current implementation is heavily influenced by the original patch
series [2][3] from Mike Turquette. However, the current implementation
supports only device tree based information.

[1] http://www.ti.com/pdfs/wtbu/smartreflex_whitepaper.pdf
[2] http://marc.info/?l=linux-omap&m=134931341818379&w=2
[3] http://marc.info/?l=linux-arm-kernel&m=134931402406853&w=2

[[e-mail]: co-developer]
Signed-off-by: Nishanth Menon <[e-mail]>
Signed-off-by: Andrii.Tseglytskyi <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/regulator/ti-abb-regulator.txt

···
+Adaptive Body Bias(ABB) SoC internal LDO regulator for Texas Instruments SoCs
+
+Required Properties:
+- compatible: Should be one of:
+  - "ti,abb-v1" for older SoCs like OMAP3
+  - "ti,abb-v2" for newer SoCs like OMAP4, OMAP5
+- reg: Address and length of the register set for the device. It contains
+  the information of registers in the same order as described by reg-names
+- reg-names: Should contain the reg names
+  - "base-address"	- contains base address of ABB module
+  - "int-address"	- contains address of interrupt register for ABB module
+  (also see Optional properties)
+- #address-cell: should be 0
+- #size-cell: should be 0
+- clocks: should point to the clock node used by ABB module
+- ti,settling-time: Settling time in uSecs from SoC documentation for ABB module
+	to settle down(target time for SR2_WTCNT_VALUE).
+- ti,clock-cycles: SoC specific data about count of system ti,clock-cycles used for
+	computing settling time from SoC Documentation for ABB module(clock
+	cycles for SR2_WTCNT_VALUE).
+- ti,tranxdone-status-mask: Mask to the int-register to write-to-clear mask
+	indicating LDO tranxdone (operation complete).
+- ti,abb_info: An array of 6-tuples u32 items providing information about ABB
+	configuration needed per operational voltage of the device.
+	Each item consists of the following in the same order:
+	volt: voltage in uV - Only used to index ABB information.
+	ABB mode: one of the following:
+		0-bypass
+		1-Forward Body Bias(FBB)
+		3-Reverse Body Bias(RBB)
+	efuse:	(see Optional properties)
+	RBB enable efuse Mask:	(See Optional properties)
+	FBB enable efuse Mask:	(See Optional properties)
+	Vset value efuse Mask:	(See Optional properties)
+
+	NOTE: If more than 1 entry is present, then regulator is setup to change
+	      voltage, allowing for various modes to be selected indexed off
+	      the regulator. Further, ABB LDOs are considered always-on by
+	      default.
+
+Optional Properties:
+- reg-names: In addition to the required properties, the following are optional
+  - "efuse-address"	- Contains efuse base address used to pick up ABB info.
+  - "ldo-address"	- Contains address of ABB LDO overide register address.
+	"efuse-address" is required for this.
+- ti,ldovbb-vset-mask	- Required if ldo-address is set, mask for LDO override
+	register to provide override vset value.
+- ti,ldovbb-override-mask - Required if ldo-address is set, mask for LDO
+	override register to enable override vset value.
+- ti,abb_opp_sel: Addendum to the description in required properties
+	efuse: Mandatory if 'efuse-address' register is defined. Provides offset
+	       from efuse-address to pick up ABB characteristics. Set to 0 if
+	       'efuse-address' is not defined.
+	RBB enable efuse Mask:	Optional if 'efuse-address' register is defined.
+		'ABB mode' is force set to RBB mode if value at "efuse-address"
+		+ efuse maps to RBB mask. Set to 0 to ignore this.
+	FBB enable efuse Mask:	Optional if 'efuse-address' register is defined.
+		'ABB mode' is force set to FBB mode if value at "efuse-address"
+		+ efuse maps to FBB mask (valid only if RBB mask does not match)
+		Set to 0 to ignore this.
+	Vset value efuse Mask:	Mandatory if ldo-address is set. Picks up from
+		efuse the value to set in 'ti,ldovbb-vset-mask' at ldo-address.
+
+Example #1: Simplest configuration (no efuse data, hard coded ABB table):
+abb_x: regulator-abb-x {
+	compatible = "ti,abb-v1";
+	regulator-name = "abb_x";
+	#address-cell = <0>;
+	#size-cells = <0>;
+	reg = <0x483072f0 0x8>, <0x48306818 0x4>;
+	reg-names = "base-address", "int-address";
+	ti,tranxdone-status-mask = <0x4000000>;
+	clocks = <&sysclk>;
+	ti,settling-time = <30>;
+	ti,clock-cycles = <8>;
+	ti,abb_info = <
+	/* uV		ABB	efuse	rbb_m	fbb_m	vset_m */
+	1012500		0	0	0	0	0 /* Bypass */
+	1200000		3	0	0	0	0 /* RBB mandatory */
+	1320000		1	0	0	0	0 /* FBB mandatory */
+	>;
+};
+
+Example #2: Efuse bits contain ABB mode setting (no LDO override capability)
+abb_y: regulator-abb-y {
+	compatible = "ti,abb-v2";
+	regulator-name = "abb_y";
+	#address-cell = <0>;
+	#size-cells = <0>;
+	reg = <0x4a307bd0 0x8>, <0x4a306014 0x4>, <0x4A002268 0x8>;
+	reg-names = "base-address", "int-address", "efuse-address";
+	ti,tranxdone-status-mask = <0x4000000>;
+	clocks = <&sysclk>;
+	ti,settling-time = <50>;
+	ti,clock-cycles = <16>;
+	ti,abb_info = <
+	/* uV		ABB	efuse	rbb_m	fbb_m	vset_m */
+	975000		0	0	0	0	0 /* Bypass */
+	1012500		0	0	0x40000	0	0 /* RBB optional */
+	1200000		0	0x4	0	0x40000	0 /* FBB optional */
+	1320000		1	0	0	0	0 /* FBB mandatory */
+	>;
+};
+
+Example #3: Efuse bits contain ABB mode setting and LDO override capability
+abb_z: regulator-abb-z {
+	compatible = "ti,abb-v2";
+	regulator-name = "abb_z";
+	#address-cell = <0>;
+	#size-cells = <0>;
+	reg = <0x4ae07ce4 0x8>, <0x4ae06010 0x4>,
+	      <0x4a002194 0x8>, <0x4ae0C314 0x4>;
+	reg-names = "base-address", "int-address",
+		    "efuse-address", "ldo-address";
+	ti,tranxdone-status-mask = <0x8000000>;
+	/* LDOVBBMM_MUX_CTRL */
+	ti,ldovbb-override-mask = <0x400>;
+	/* LDOVBBMM_VSET_OUT */
+	ti,ldovbb-vset-mask = <0x1F>;
+	clocks = <&sysclk>;
+	ti,settling-time = <50>;
+	ti,clock-cycles = <16>;
+	ti,abb_info = <
+	/* uV	ABB	efuse	rbb_m	fbb_m	vset_m */
+	975000	0	0	0	0	0	/* Bypass */
+	1200000	0	0x4	0	0x40000	0x1f00	/* FBB optional, vset */
+	>;
+};

drivers/regulator/Kconfig

···
 	  This driver supports the voltage regulators provided by
 	  this family of companion chips.
 
+config REGULATOR_TI_ABB
+	bool "TI Adaptive Body Bias on-chip LDO"
+	depends on ARCH_OMAP
+	help
+	  Select this option to support Texas Instruments' on-chip Adaptive Body
+	  Bias (ABB) LDO regulators. It is recommended that this option be
+	  enabled on required TI SoC. Certain Operating Performance Points
+	  on TI SoCs may be unstable without enabling this as it provides
+	  device specific optimized bias to allow/optimize functionality.
+
 config REGULATOR_VEXPRESS
 	tristate "Versatile Express regulators"
 	depends on VEXPRESS_CONFIG

drivers/regulator/Makefile

···
 obj-$(CONFIG_REGULATOR_TPS65912) += tps65912-regulator.o
 obj-$(CONFIG_REGULATOR_TPS80031) += tps80031-regulator.o
 obj-$(CONFIG_REGULATOR_TWL4030) += twl-regulator.o
+obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
 obj-$(CONFIG_REGULATOR_VEXPRESS) += vexpress.o
 obj-$(CONFIG_REGULATOR_WM831X) += wm831x-dcdc.o
 obj-$(CONFIG_REGULATOR_WM831X) += wm831x-isink.o

drivers/regulator/ti-abb-regulator.c

···
+/*
+ * Texas Instruments SoC Adaptive Body Bias(ABB) Regulator
+ *
+ * Copyright (C) 2011 Texas Instruments, Inc.
+ * Mike Turquette <[e-mail]>
+ *
+ * Copyright (C) 2012-2013 Texas Instruments, Inc.
+ * Andrii Tseglytskyi <[e-mail]>
+ * Nishanth Menon <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+
+/*
+ * ABB LDO operating states:
+ * NOMINAL_OPP:	bypasses the ABB LDO
+ * FAST_OPP:	sets ABB LDO to Forward Body-Bias
+ * SLOW_OPP:	sets ABB LDO to Reverse Body-Bias
+ */
+#define TI_ABB_NOMINAL_OPP	0
+#define TI_ABB_FAST_OPP		1
+#define TI_ABB_SLOW_OPP		3
+
+/**
+ * struct ti_abb_info - ABB information per voltage setting
+ * @opp_sel:	one of TI_ABB macro
+ * @vset:	(optional) vset value that LDOVBB needs to be overriden with.
+ *
+ * Array of per voltage entries organized in the same order as regulator_desc's
+ * volt_table list. (selector is used to index from this array)
+ */
+struct ti_abb_info {
+	u32 opp_sel;
+	u32 vset;
+};
+
+/**
+ * struct ti_abb_reg - Register description for ABB block
+ * @setup_reg:			setup register offset from base
+ * @control_reg:		control register offset from base
+ * @sr2_wtcnt_value_mask:	setup register- sr2_wtcnt_value mask
+ * @fbb_sel_mask:		setup register- FBB sel mask
+ * @rbb_sel_mask:		setup register- RBB sel mask
+ * @sr2_en_mask:		setup register- enable mask
+ * @opp_change_mask:		control register - mask to trigger LDOVBB change
+ * @opp_sel_mask:		control register - mask for mode to operate
+ */
+struct ti_abb_reg {
+	u32 setup_reg;
+	u32 control_reg;
+
+	/* Setup register fields */
+	u32 sr2_wtcnt_value_mask;
+	u32 fbb_sel_mask;
+	u32 rbb_sel_mask;
+	u32 sr2_en_mask;
+
+	/* Control register fields */
+	u32 opp_change_mask;
+	u32 opp_sel_mask;
+};
+
+/**
+ * struct ti_abb - ABB instance data
+ * @rdesc:			regulator descriptor
+ * @clk:			clock(usually sysclk) supplying ABB block
+ * @base:			base address of ABB block
+ * @int_base:			interrupt register base address
+ * @efuse_base:			(optional) efuse base address for ABB modes
+ * @ldo_base:			(optional) LDOVBB vset override base address
+ * @regs:			pointer to struct ti_abb_reg for ABB block
+ * @txdone_mask:		mask on int_base for tranxdone interrupt
+ * @ldovbb_override_mask:	mask to ldo_base for overriding default LDO VBB
+ *				vset with value from efuse
+ * @ldovbb_vset_mask:		mask to ldo_base for providing the VSET override
+ * @info:			array to per voltage ABB configuration
+ * @current_info_idx:		current index to info
+ * @settling_time:		SoC specific settling time for LDO VBB
+ */
+struct ti_abb {
+	struct regulator_desc rdesc;
+	struct clk *clk;
+	void __iomem *base;
+	void __iomem *int_base;
+	void __iomem *efuse_base;
+	void __iomem *ldo_base;
+
+	const struct ti_abb_reg *regs;
+	u32 txdone_mask;
+	u32 ldovbb_override_mask;
+	u32 ldovbb_vset_mask;
+
+	struct ti_abb_info *info;
+	int current_info_idx;
+
+	u32 settling_time;
+};
+
+/**
+ * ti_abb_rmw() - handy wrapper to set specific register bits
+ * @mask:	mask for register field
+ * @value:	value shifted to mask location and written
+ * @offset:	offset of register
+ * @base:	base address
+ *
+ * Return: final register value (may be unused)
+ */
+static inline u32 ti_abb_rmw(u32 mask, u32 value, u32 offset,
+			     void __iomem *base)
+{
+	u32 val;
+
+	val = readl(base + offset);
+	val &= ~mask;
+	val |= (value << __ffs(mask)) & mask;
+	writel(val, base + offset);
+
+	return val;
+}
+
+/**
+ * ti_abb_check_txdone() - handy wrapper to check ABB tranxdone status
+ * @abb:	pointer to the abb instance
+ *
+ * Return: true or false
+ */
+static inline bool ti_abb_check_txdone(const struct ti_abb *abb)
+{
+	return !!(readl(abb->int_base) & abb->txdone_mask);
+}
+
+/**
+ * ti_abb_clear_txdone() - handy wrapper to clear ABB tranxdone status
+ * @abb:	pointer to the abb instance
+ */
+static inline void ti_abb_clear_txdone(const struct ti_abb *abb)
+{
+	writel(abb->txdone_mask, abb->int_base);
+};
+
+/**
+ * ti_abb_wait_tranx() - waits for ABB tranxdone event
+ * @dev:	device
+ * @abb:	pointer to the abb instance
+ *
+ * Return: 0 on success or -ETIMEDOUT if the event is not cleared on time.
+ */
+static int ti_abb_wait_txdone(struct device *dev, struct ti_abb *abb)
+{
+	int timeout = 0;
+	bool status;
+
+	while (timeout++ <= abb->settling_time) {
+		status = ti_abb_check_txdone(abb);
+		if (status)
+			break;
+
+		udelay(1);
+	}
+
+	if (timeout > abb->settling_time) {
+		dev_warn_ratelimited(dev,
+				     "%s:TRANXDONE timeout(%duS) int=0x%08x\n",
+				     __func__, timeout, readl(abb->int_base));
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+/**
+ * ti_abb_clear_all_txdone() - clears ABB tranxdone event
+ * @dev:	device
+ * @abb:	pointer to the abb instance
+ *
+ * Return: 0 on success or -ETIMEDOUT if the event is not cleared on time.
+ */
+static int ti_abb_clear_all_txdone(struct device *dev, const struct ti_abb *abb)
+{
+	int timeout = 0;
+	bool status;
+
+	while (timeout++ <= abb->settling_time) {
+		ti_abb_clear_txdone(abb);
+
+		status = ti_abb_check_txdone(abb);
+		if (!status)
+			break;
+
+		udelay(1);
+	}
+
+	if (timeout > abb->settling_time) {
+		dev_warn_ratelimited(dev,
+				     "%s:TRANXDONE timeout(%duS) int=0x%08x\n",
+				     __func__, timeout, readl(abb->int_base));
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+/**
+ * ti_abb_program_ldovbb() - program LDOVBB register for override value
+ * @dev:	device
+ * @abb:	pointer to the abb instance
+ * @info:	ABB info to program
+ */
+static void ti_abb_program_ldovbb(struct device *dev, const struct ti_abb *abb,
+				  struct ti_abb_info *info)
+{
+	u32 val;
+
+	val = readl(abb->ldo_base);
+	/* clear up previous values */
+	val &= ~(abb->ldovbb_override_mask | abb->ldovbb_vset_mask);
+
+	switch (info->opp_sel) {
+	case TI_ABB_SLOW_OPP:
+	case TI_ABB_FAST_OPP:
+		val |= abb->ldovbb_override_mask;
+		val |= info->vset << __ffs(abb->ldovbb_vset_mask);
+		break;
+	}
+
+	writel(val, abb->ldo_base);
+}
+
+/**
+ * ti_abb_set_opp() - Setup ABB and LDO VBB for required bias
+ * @rdev:	regulator device
+ * @abb:	pointer to the abb instance
+ * @info:	ABB info to program
+ *
+ * Return: 0 on success or appropriate error value when fails
+ */
+static int ti_abb_set_opp(struct regulator_dev *rdev, struct ti_abb *abb,
+			  struct ti_abb_info *info)
+{
+	const struct ti_abb_reg *regs = abb->regs;
+	struct device *dev = &rdev->dev;
+	int ret;
+
+	ret = ti_abb_clear_all_txdone(dev, abb);
+	if (ret)
+		goto out;
+
+	ti_abb_rmw(regs->fbb_sel_mask | regs->rbb_sel_mask, 0, regs->setup_reg,
+		   abb->base);
+
+	switch (info->opp_sel) {
+	case TI_ABB_SLOW_OPP:
+		ti_abb_rmw(regs->rbb_sel_mask, 1, regs->setup_reg, abb->base);
+		break;
+	case TI_ABB_FAST_OPP:
+		ti_abb_rmw(regs->fbb_sel_mask, 1, regs->setup_reg, abb->base);
+		break;
+	}
+
+	/* program next state of ABB ldo */
+	ti_abb_rmw(regs->opp_sel_mask, info->opp_sel, regs->control_reg,
+		   abb->base);
+
+	/* program LDO VBB vset override if needed */
+	if (abb->ldo_base)
+		ti_abb_program_ldovbb(dev, abb, info);
+
+	/* Initiate ABB ldo change */
+	ti_abb_rmw(regs->opp_change_mask, 1, regs->control_reg, abb->base);
+
+	/* Wait for ABB LDO to complete transition to new Bias setting */
+	ret = ti_abb_wait_txdone(dev, abb);
+	if (ret)
+		goto out;
+
+	ret = ti_abb_clear_all_txdone(dev, abb);
+	if (ret)
+		goto out;
+
+out:
+	return ret;
+}
+
+/**
+ * ti_abb_set_voltage_sel() - regulator accessor function to set ABB LDO
+ * @rdev:	regulator device
+ * @sel:	selector to index into required ABB LDO settings (maps to
+ *		regulator descriptor's volt_table)
+ *
+ * Return: 0 on success or appropriate error value when fails
+ */
+static int ti_abb_set_voltage_sel(struct regulator_dev *rdev, unsigned sel)
+{
+	const struct regulator_desc *desc = rdev->desc;
+	struct ti_abb *abb = rdev_get_drvdata(rdev);
+	struct device *dev = &rdev->dev;
+	struct ti_abb_info *info, *oinfo;
+	int ret = 0;
+
+	if (!abb) {
+		dev_err_ratelimited(dev, "%s: No regulator drvdata\n",
+				    __func__);
+		return -ENODEV;
+	}
+
+	if (!desc->n_voltages || !abb->info) {
+		dev_err_ratelimited(dev,
+				    "%s: No valid voltage table entries?\n",
+				    __func__);
+		return -EINVAL;
+	}
+
+	if (sel >= desc->n_voltages) {
+		dev_err(dev, "%s: sel idx(%d) >= n_voltages(%d)\n", __func__,
+			sel, desc->n_voltages);
+		return -EINVAL;
+	}
+
+	/* If we are in the same index as we were, nothing to do here! */
+	if (sel == abb->current_info_idx) {
+		dev_dbg(dev, "%s: Already at sel=%d\n", __func__, sel);
+		return ret;
+	}
+
+	/* If data is exactly the same, then just update index, no change */
+	info = &abb->info[sel];
+	oinfo = &abb->info[abb->current_info_idx];
+	if (!memcmp(info, oinfo, sizeof(*info))) {
+		dev_dbg(dev, "%s: Same data new idx=%d, old idx=%d\n", __func__,
+			sel, abb->current_info_idx);
+		goto out;
+	}
+
+	ret = ti_abb_set_opp(rdev, abb, info);
+
+out:
+	if (!ret)
+		abb->current_info_idx = sel;
+	else
+		dev_err_ratelimited(dev,
+				    "%s: Volt[%d] idx[%d] mode[%d] Fail(%d)\n",
+				    __func__, desc->volt_table[sel], sel,
+				    info->opp_sel, ret);
+	return ret;
+}
+
+/**
+ * ti_abb_get_voltage_sel() - Regulator accessor to get current ABB LDO setting
+ * @rdev:	regulator device
+ *
+ * Return: 0 on success or appropriate error value when fails
+ */
+static int ti_abb_get_voltage_sel(struct regulator_dev *rdev)
+{
+	const struct regulator_desc *desc = rdev->desc;
+	struct ti_abb *abb = rdev_get_drvdata(rdev);
+	struct device *dev = &rdev->dev;
+
+	if (!abb) {
+		dev_err_ratelimited(dev, "%s: No regulator drvdata\n",
+				    __func__);
+		return -ENODEV;
+	}
+
+	if (!desc->n_voltages || !abb->info) {
+		dev_err_ratelimited(dev,
+				    "%s: No valid voltage table entries?\n",
+				    __func__);
+		return -EINVAL;
+	}
+
+	if (abb->current_info_idx > (int)desc->n_voltages) {
+		dev_err(dev, "%s: Corrupted data? idx(%d) > n_voltages(%d)\n",
+			__func__, abb->current_info_idx, desc->n_voltages);
+		return -EINVAL;
+	}
+
+	return abb->current_info_idx;
+}
+
+/**
+ * ti_abb_init_timings() - setup ABB clock timing for the current platform
+ * @dev:	device
+ * @abb:	pointer to the abb instance
+ *
+ * Return: 0 if timing is updated, else returns error result.
+ */
+static int ti_abb_init_timings(struct device *dev, struct ti_abb *abb)
+{
+	u32 clock_cycles;
+	u32 clk_rate, sr2_wt_cnt_val, cycle_rate;
+	const struct ti_abb_reg *regs = abb->regs;
+	int ret;
+	char *pname = "ti,settling-time";
+
+	/* read device tree properties */
+	ret = of_property_read_u32(dev->of_node, pname, &abb->settling_time);
+	if (ret) {
+		dev_err(dev, "Unable to get property '%s'(%d)\n", pname, ret);
+		return ret;
+	}
+
+	/* ABB LDO cannot be settle in 0 time */
+	if (!abb->settling_time) {
+		dev_err(dev, "Invalid property:'%s' set as 0!\n", pname);
+		return -EINVAL;
+	}
+
+	pname = "ti,clock-cycles";
+	ret = of_property_read_u32(dev->of_node, pname, &clock_cycles);
+	if (ret) {
+		dev_err(dev, "Unable to get property '%s'(%d)\n", pname, ret);
+		return ret;
+	}
+	/* ABB LDO cannot be settle in 0 clock cycles */
+	if (!clock_cycles) {
+		dev_err(dev, "Invalid property:'%s' set as 0!\n", pname);
+		return -EINVAL;
+	}
+
+	abb->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(abb->clk)) {
+		ret = PTR_ERR(abb->clk);
+		dev_err(dev, "%s: Unable to get clk(%d)\n", __func__, ret);
+		return ret;
+	}
+
+	/*
+	 * 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.
+	 */
+
+	/* Convert SYS_CLK rate to MHz & prevent divide by zero */
+	clk_rate = DIV_ROUND_CLOSEST(clk_get_rate(abb->clk), 1000000);
+
+	/* Calculate cycle rate */
+	cycle_rate = DIV_ROUND_CLOSEST(clock_cycles * 10, clk_rate);
+
+	/* Calulate SR2_WTCNT_VALUE */
+	sr2_wt_cnt_val = DIV_ROUND_CLOSEST(abb->settling_time * 10, cycle_rate);
+
+	dev_dbg(dev, "%s: Clk_rate=%ld, sr2_cnt=0x%08x\n", __func__,
+		clk_get_rate(abb->clk), sr2_wt_cnt_val);
+
+	ti_abb_rmw(regs->sr2_wtcnt_value_mask, sr2_wt_cnt_val, regs->setup_reg,
+		   abb->base);
+
+	return 0;
+}
+
+/**
+ * ti_abb_init_table() - Initialize ABB table from device tree
+ * @dev:	device
+ * @abb:	pointer to the abb instance
+ * @rinit_data:	regulator initdata
+ *
+ * Return: 0 on success or appropriate error value when fails
+ */
+static int ti_abb_init_table(struct device *dev, struct ti_abb *abb,
+			     struct regulator_init_data *rinit_data)
+{
+	struct ti_abb_info *info;
+	const struct property *prop;
+	const __be32 *abb_info;
+	const u32 num_values = 6;
+	char *pname = "ti,abb_info";
+	u32 num_entries, i;
+	unsigned int *volt_table;
+	int min_uV = INT_MAX, max_uV = 0;
+	struct regulation_constraints *c = &rinit_data->constraints;
+
+	prop = of_find_property(dev->of_node, pname, NULL);
+	if (!prop) {
+		dev_err(dev, "No '%s' property?\n", pname);
+		return -ENODEV;
+	}
+
+	if (!prop->value) {
+		dev_err(dev, "Empty '%s' property?\n", pname);
+		return -ENODATA;
+	}
+
+	/*
+	 * Each abb_info is a set of n-tuple, where n is num_values, consisting
+	 * of voltage and a set of detection logic for ABB information for that
+	 * voltage to apply.
+	 */
+	num_entries = prop->length / sizeof(u32);
+	if (!num_entries || (num_entries % num_values)) {
+		dev_err(dev, "All '%s' list entries need %d vals\n", pname,
+			num_values);
+		return -EINVAL;
+	}
+	num_entries /= num_values;
+
+	info = devm_kzalloc(dev, sizeof(*info) * num_entries, GFP_KERNEL);
+	if (!info) {
+		dev_err(dev, "Can't allocate info table for '%s' property\n",
+			pname);
+		return -ENOMEM;
+	}
+	abb->info = info;
+
+	volt_table = devm_kzalloc(dev, sizeof(unsigned int) * num_entries,
+				  GFP_KERNEL);
+	if (!volt_table) {
+		dev_err(dev, "Can't allocate voltage table for '%s' property\n",
+			pname);
+		return -ENOMEM;
+	}
+
+	abb->rdesc.n_voltages = num_entries;
+	abb->rdesc.volt_table = volt_table;
+	/* We do not know where the OPP voltage is at the moment */
+	abb->current_info_idx = -EINVAL;
+
+	abb_info = prop->value;
+	for (i = 0; i < num_entries; i++, info++, volt_table++) {
+		u32 efuse_offset, rbb_mask, fbb_mask, vset_mask;
+		u32 efuse_val;
+
+		/* NOTE: num_values should equal to entries picked up here */
+		*volt_table = be32_to_cpup(abb_info++);
+		info->opp_sel = be32_to_cpup(abb_info++);
+		efuse_offset = be32_to_cpup(abb_info++);
+		rbb_mask = be32_to_cpup(abb_info++);
+		fbb_mask = be32_to_cpup(abb_info++);
+		vset_mask = be32_to_cpup(abb_info++);
+
+		dev_dbg(dev,
+			"[%d]v=%d ABB=%d ef=0x%x rbb=0x%x fbb=0x%x vset=0x%x\n",
+			i, *volt_table, info->opp_sel, efuse_offset, rbb_mask,
+			fbb_mask, vset_mask);
+
+		/* Find min/max for voltage set */
+		if (min_uV > *volt_table)
+			min_uV = *volt_table;
+		if (max_uV < *volt_table)
+			max_uV = *volt_table;
+
+		if (!abb->efuse_base) {
+			/* Ignore invalid data, but warn to help cleanup */
+			if (efuse_offset || rbb_mask || fbb_mask || vset_mask)
+				dev_err(dev, "prop '%s': v=%d,bad efuse/mask\n",
+					pname, *volt_table);
+			goto check_abb;
+		}
+
+		efuse_val = readl(abb->efuse_base + efuse_offset);
+
+		/* Use ABB recommendation from Efuse */
+		if (efuse_val & rbb_mask)
+			info->opp_sel = TI_ABB_SLOW_OPP;
+		else if (efuse_val & fbb_mask)
+			info->opp_sel = TI_ABB_FAST_OPP;
+		else if (rbb_mask || fbb_mask)
+			info->opp_sel = TI_ABB_NOMINAL_OPP;
+
+		dev_dbg(dev,
+			"[%d]v=%d efusev=0x%x final ABB=%d\n",
+			i, *volt_table, efuse_val, info->opp_sel);
+
+		/* Use recommended Vset bits from Efuse */
+		if (!abb->ldo_base) {
+			if (vset_mask)
+				dev_err(dev, "prop'%s':v=%d vst=%x LDO base?\n",
+					pname, *volt_table, vset_mask);
+			continue;
+		}
+		info->vset = efuse_val & vset_mask >> __ffs(vset_mask);
+		dev_dbg(dev, "[%d]v=%d vset=%x\n", i, *volt_table, info->vset);
+check_abb:
+		switch (info->opp_sel) {
+		case TI_ABB_NOMINAL_OPP:
+		case TI_ABB_FAST_OPP:
+		case TI_ABB_SLOW_OPP:
+			/* Valid values */
+			break;
+		default:
+			dev_err(dev, "%s:[%d]v=%d, ABB=%d is invalid! Abort!\n",
+				__func__, i, *volt_table, info->opp_sel);
+			return -EINVAL;
+		}
+	}
+
+	/* Setup the min/max voltage constraints from the supported list */
+	c->min_uV = min_uV;
+	c->max_uV = max_uV;
+
+	return 0;
+}
+
+static struct regulator_ops ti_abb_reg_ops = {
+	.list_voltage = regulator_list_voltage_table,
+
+	.set_voltage_sel = ti_abb_set_voltage_sel,
+	.get_voltage_sel = ti_abb_get_voltage_sel,
+};
+
+/* Default ABB block offsets, IF this changes in future, create new one */
+static const struct ti_abb_reg abb_regs_v1 = {
+	/* WARNING: registers are wrongly documented in TRM */
+	.setup_reg		= 0x04,
+	.control_reg		= 0x00,
+
+	.sr2_wtcnt_value_mask	= (0xff << 8),
+	.fbb_sel_mask		= (0x01 << 2),
+	.rbb_sel_mask		= (0x01 << 1),
+	.sr2_en_mask		= (0x01 << 0),
+
+	.opp_change_mask	= (0x01 << 2),
+	.opp_sel_mask		= (0x03 << 0),
+};
+
+static const struct ti_abb_reg abb_regs_v2 = {
+	.setup_reg		= 0x00,
+	.control_reg		= 0x04,
+
+	.sr2_wtcnt_value_mask	= (0xff << 8),
+	.fbb_sel_mask		= (0x01 << 2),
+	.rbb_sel_mask		= (0x01 << 1),
+	.sr2_en_mask		= (0x01 << 0),
+
+	.opp_change_mask	= (0x01 << 2),
+	.opp_sel_mask		= (0x03 << 0),
+};
+
+static const struct of_device_id ti_abb_of_match[] = {
+	{.compatible = "ti,abb-v1", .data = &abb_regs_v1},
+	{.compatible = "ti,abb-v2", .data = &abb_regs_v2},
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, ti_abb_of_match);
+
+/**
+ * ti_abb_probe() - Initialize an ABB ldo instance
+ * @pdev: ABB platform device
+ *
+ * Initializes an individual ABB LDO for required Body-Bias. ABB is used to
+ * addional bias supply to SoC modules for power savings or mandatory stability
+ * configuration at certain Operating Performance Points(OPPs).
+ *
+ * Return: 0 on success or appropriate error value when fails
+ */
+static int ti_abb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct of_device_id *match;
+	struct resource *res;
+	struct ti_abb *abb;
+	struct regulator_init_data *initdata = NULL;
+	struct regulator_dev *rdev = NULL;
+	struct regulator_desc *desc;
+	struct regulation_constraints *c;
+	struct regulator_config config = { };
+	char *pname;
+	int ret = 0;
+
+	match = of_match_device(ti_abb_of_match, dev);
+	if (!match) {
+		/* We do not expect this to happen */
+		ret = -ENODEV;
+		dev_err(dev, "%s: Unable to match device\n", __func__);
+		goto err;
+	}
+	if (!match->data) {
+		ret = -EINVAL;
+		dev_err(dev, "%s: Bad data in match\n", __func__);
+		goto err;
+	}
+
+	abb = devm_kzalloc(dev, sizeof(struct ti_abb), GFP_KERNEL);
+	if (!abb) {
+		dev_err(dev, "%s: Unable to allocate ABB struct\n", __func__);
+		ret = -ENOMEM;
+		goto err;
+	}
+	abb->regs = match->data;
+
+	/* Map ABB resources */
+	pname = "base-address";
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, pname);
+	if (!res) {
+		dev_err(dev, "Missing '%s' IO resource\n", pname);
+		ret = -ENODEV;
+		goto err;
+	}
+	abb->base = devm_request_and_ioremap(dev, res);
+	if (!abb->base) {
+		dev_err(dev, "Unable to map '%s'\n", pname);
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	pname = "int-address";
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, pname);
+	if (!res) {
+		dev_err(dev, "Missing '%s' IO resource\n", pname);
+		ret = -ENODEV;
+		goto err;
+	}
+	/*
+	 * We may have shared interrupt register offsets which are
+	 * write-1-to-clear between domains ensuring exclusivity.
+	 */
+	abb->int_base = devm_ioremap_nocache(dev, res->start,
+					     resource_size(res));
+	if (!abb->int_base) {
+		dev_err(dev, "Unable to map '%s'\n", pname);
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	/* Map Optional resources */
+	pname = "efuse-address";
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, pname);
+	if (!res) {
+		dev_dbg(dev, "Missing '%s' IO resource\n", pname);
+		ret = -ENODEV;
+		goto skip_opt;
+	}
+
+	/*
+	 * We may have shared efuse register offsets which are read-only
+	 * between domains
+	 */
+	abb->efuse_base = devm_ioremap_nocache(dev, res->start,
+					       resource_size(res));
+	if (!abb->efuse_base) {
+		dev_err(dev, "Unable to map '%s'\n", pname);
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	pname = "ldo-address";
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, pname);
+	if (!res) {
+		dev_dbg(dev, "Missing '%s' IO resource\n", pname);
+		ret = -ENODEV;
+		goto skip_opt;
+	}
+	abb->ldo_base = devm_request_and_ioremap(dev, res);
+	if (!abb->ldo_base) {
+		dev_err(dev, "Unable to map '%s'\n", pname);
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	/* IF ldo_base is set, the following are mandatory */
+	pname = "ti,ldovbb-override-mask";
+	ret =
+	    of_property_read_u32(pdev->dev.of_node, pname,
+				 &abb->ldovbb_override_mask);
+	if (ret) {
+		dev_err(dev, "Missing '%s' (%d)\n", pname, ret);
+		goto err;
+	}
+	if (!abb->ldovbb_override_mask) {
+		dev_err(dev, "Invalid property:'%s' set as 0!\n", pname);
+		ret = -EINVAL;
+		goto err;
+	}
+
+	pname = "ti,ldovbb-vset-mask";
+	ret =
+	    of_property_read_u32(pdev->dev.of_node, pname,
+				 &abb->ldovbb_vset_mask);
+	if (ret) {
+		dev_err(dev, "Missing '%s' (%d)\n", pname, ret);
+		goto err;
+	}
+	if (!abb->ldovbb_vset_mask) {
+		dev_err(dev, "Invalid property:'%s' set as 0!\n", pname);
+		ret = -EINVAL;
+		goto err;
+	}
+
+skip_opt:
+	pname = "ti,tranxdone-status-mask";
+	ret =
+	    of_property_read_u32(pdev->dev.of_node, pname,
+				 &abb->txdone_mask);
+	if (ret) {
+		dev_err(dev, "Missing '%s' (%d)\n", pname, ret);
+		goto err;
+	}
+	if (!abb->txdone_mask) {
+		dev_err(dev, "Invalid property:'%s' set as 0!\n", pname);
+		ret = -EINVAL;
+		goto err;
+	}
+
+	initdata = of_get_regulator_init_data(dev, pdev->dev.of_node);
+	if (!initdata) {
+		ret = -ENOMEM;
+		dev_err(dev, "%s: Unable to alloc regulator init data\n",
+			__func__);
+		goto err;
+	}
+
+	/* init ABB opp_sel table */
+	ret = ti_abb_init_table(dev, abb, initdata);
+	if (ret)
+		goto err;
+
+	/* init ABB timing */
+	ret = ti_abb_init_timings(dev, abb);
+	if (ret)
+		goto err;
+
+	desc = &abb->rdesc;
+	desc->name = dev_name(dev);
+	desc->owner = THIS_MODULE;
+	desc->type = REGULATOR_VOLTAGE;
+	desc->ops = &ti_abb_reg_ops;
+
+	c = &initdata->constraints;
+	if (desc->n_voltages > 1)
+		c->valid_ops_mask |= REGULATOR_CHANGE_VOLTAGE;
+	c->always_on = true;
+
+	config.dev = dev;
+	config.init_data = initdata;
+	config.driver_data = abb;
+	config.of_node = pdev->dev.of_node;
+
+	rdev = regulator_register(desc, &config);
+	if (IS_ERR(rdev)) {
+		ret = PTR_ERR(rdev);
+		dev_err(dev, "%s: failed to register regulator(%d)\n",
+			__func__, ret);
+		goto err;
+	}
+	platform_set_drvdata(pdev, rdev);
+
+	/* Enable the ldo if not already done by bootloader */
+	ti_abb_rmw(abb->regs->sr2_en_mask, 1, abb->regs->setup_reg, abb->base);
+
+	return 0;
+
+err:
+	dev_err(dev, "%s: Failed to initialize(%d)\n", __func__, ret);
+	return ret;
+}
+
+/**
+ * ti_abb_remove() - cleanups
+ * @pdev: ABB platform device
+ *
+ * Return: 0
+ */
+static int ti_abb_remove(struct platform_device *pdev)
+{
+	struct regulator_dev *rdev = platform_get_drvdata(pdev);
+
+	regulator_unregister(rdev);
+	return 0;
+}
+
+MODULE_ALIAS("platform:ti_abb");
+
+static struct platform_driver ti_abb_driver = {
+	.probe = ti_abb_probe,
+	.remove = ti_abb_remove,
+	.driver = {
+		   .name = "ti_abb",
+		   .owner = THIS_MODULE,
+		   .of_match_table = of_match_ptr(ti_abb_of_match),
+		   },
+};
+module_platform_driver(ti_abb_driver);
+
+MODULE_DESCRIPTION("Texas Instruments ABB LDO regulator driver");
+MODULE_AUTHOR("Texas Instruments Inc.");
+MODULE_LICENSE("GPL v2");