diff --git a/drivers/mfd/wm831x-core.c b/drivers/mfd/wm831x-core.c
index eb63d22..42bef1d 100644
--- a/drivers/mfd/wm831x-core.c
+++ b/drivers/mfd/wm831x-core.c
@@ -15,11 +15,14 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/delay.h>
 #include <linux/mfd/core.h>
 
 #include <linux/mfd/wm831x/core.h>
 #include <linux/mfd/wm831x/pdata.h>
 #include <linux/mfd/wm831x/irq.h>
+#include <linux/mfd/wm831x/auxadc.h>
 
 enum wm831x_parent {
 	WM8310 = 0,
@@ -244,6 +247,103 @@
 }
 EXPORT_SYMBOL_GPL(wm831x_set_bits);
 
+/**
+ * wm831x_auxadc_read: Read a value from the WM831x AUXADC
+ *
+ * @wm831x: Device to read from.
+ * @input: AUXADC input to read.
+ */
+int wm831x_auxadc_read(struct wm831x *wm831x, enum wm831x_auxadc input)
+{
+	int tries = 10;
+	int ret, src;
+
+	mutex_lock(&wm831x->auxadc_lock);
+
+	ret = wm831x_set_bits(wm831x, WM831X_AUXADC_CONTROL,
+			      WM831X_AUX_ENA, WM831X_AUX_ENA);
+	if (ret < 0) {
+		dev_err(wm831x->dev, "Failed to enable AUXADC: %d\n", ret);
+		goto out;
+	}
+
+	/* We force a single source at present */
+	src = input;
+	ret = wm831x_reg_write(wm831x, WM831X_AUXADC_SOURCE,
+			       1 << src);
+	if (ret < 0) {
+		dev_err(wm831x->dev, "Failed to set AUXADC source: %d\n", ret);
+		goto out;
+	}
+
+	ret = wm831x_set_bits(wm831x, WM831X_AUXADC_CONTROL,
+			      WM831X_AUX_CVT_ENA, WM831X_AUX_CVT_ENA);
+	if (ret < 0) {
+		dev_err(wm831x->dev, "Failed to start AUXADC: %d\n", ret);
+		goto disable;
+	}
+
+	do {
+		msleep(1);
+
+		ret = wm831x_reg_read(wm831x, WM831X_AUXADC_CONTROL);
+		if (ret < 0)
+			ret = WM831X_AUX_CVT_ENA;
+	} while ((ret & WM831X_AUX_CVT_ENA) && --tries);
+
+	if (ret & WM831X_AUX_CVT_ENA) {
+		dev_err(wm831x->dev, "Timed out reading AUXADC\n");
+		ret = -EBUSY;
+		goto disable;
+	}
+
+	ret = wm831x_reg_read(wm831x, WM831X_AUXADC_DATA);
+	if (ret < 0) {
+		dev_err(wm831x->dev, "Failed to read AUXADC data: %d\n", ret);
+	} else {
+		src = ((ret & WM831X_AUX_DATA_SRC_MASK)
+		       >> WM831X_AUX_DATA_SRC_SHIFT) - 1;
+
+		if (src == 14)
+			src = WM831X_AUX_CAL;
+
+		if (src != input) {
+			dev_err(wm831x->dev, "Data from source %d not %d\n",
+				src, input);
+			ret = -EINVAL;
+		} else {
+			ret &= WM831X_AUX_DATA_MASK;
+		}
+	}
+
+disable:
+	wm831x_set_bits(wm831x, WM831X_AUXADC_CONTROL, WM831X_AUX_ENA, 0);
+out:
+	mutex_unlock(&wm831x->auxadc_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(wm831x_auxadc_read);
+
+/**
+ * wm831x_auxadc_read_uv: Read a voltage from the WM831x AUXADC
+ *
+ * @wm831x: Device to read from.
+ * @input: AUXADC input to read.
+ */
+int wm831x_auxadc_read_uv(struct wm831x *wm831x, enum wm831x_auxadc input)
+{
+	int ret;
+
+	ret = wm831x_auxadc_read(wm831x, input);
+	if (ret < 0)
+		return ret;
+
+	ret *= 1465;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(wm831x_auxadc_read_uv);
+
 static struct resource wm831x_dcdc1_resources[] = {
 	{
 		.start = WM831X_DC1_CONTROL_1,
@@ -1084,6 +1184,7 @@
 
 	mutex_init(&wm831x->io_lock);
 	mutex_init(&wm831x->key_lock);
+	mutex_init(&wm831x->auxadc_lock);
 	dev_set_drvdata(wm831x->dev, wm831x);
 
 	ret = wm831x_reg_read(wm831x, WM831X_PARENT_ID);
diff --git a/include/linux/mfd/wm831x/auxadc.h b/include/linux/mfd/wm831x/auxadc.h
new file mode 100644
index 0000000..b132067
--- /dev/null
+++ b/include/linux/mfd/wm831x/auxadc.h
@@ -0,0 +1,216 @@
+/*
+ * include/linux/mfd/wm831x/auxadc.h -- Auxiliary ADC interface for WM831x
+ *
+ * Copyright 2009 Wolfson Microelectronics PLC.
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ *  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.
+ *
+ */
+
+#ifndef __MFD_WM831X_AUXADC_H__
+#define __MFD_WM831X_AUXADC_H__
+
+/*
+ * R16429 (0x402D) - AuxADC Data
+ */
+#define WM831X_AUX_DATA_SRC_MASK                0xF000  /* AUX_DATA_SRC - [15:12] */
+#define WM831X_AUX_DATA_SRC_SHIFT                   12  /* AUX_DATA_SRC - [15:12] */
+#define WM831X_AUX_DATA_SRC_WIDTH                    4  /* AUX_DATA_SRC - [15:12] */
+#define WM831X_AUX_DATA_MASK                    0x0FFF  /* AUX_DATA - [11:0] */
+#define WM831X_AUX_DATA_SHIFT                        0  /* AUX_DATA - [11:0] */
+#define WM831X_AUX_DATA_WIDTH                       12  /* AUX_DATA - [11:0] */
+
+/*
+ * R16430 (0x402E) - AuxADC Control
+ */
+#define WM831X_AUX_ENA                          0x8000  /* AUX_ENA */
+#define WM831X_AUX_ENA_MASK                     0x8000  /* AUX_ENA */
+#define WM831X_AUX_ENA_SHIFT                        15  /* AUX_ENA */
+#define WM831X_AUX_ENA_WIDTH                         1  /* AUX_ENA */
+#define WM831X_AUX_CVT_ENA                      0x4000  /* AUX_CVT_ENA */
+#define WM831X_AUX_CVT_ENA_MASK                 0x4000  /* AUX_CVT_ENA */
+#define WM831X_AUX_CVT_ENA_SHIFT                    14  /* AUX_CVT_ENA */
+#define WM831X_AUX_CVT_ENA_WIDTH                     1  /* AUX_CVT_ENA */
+#define WM831X_AUX_SLPENA                       0x1000  /* AUX_SLPENA */
+#define WM831X_AUX_SLPENA_MASK                  0x1000  /* AUX_SLPENA */
+#define WM831X_AUX_SLPENA_SHIFT                     12  /* AUX_SLPENA */
+#define WM831X_AUX_SLPENA_WIDTH                      1  /* AUX_SLPENA */
+#define WM831X_AUX_FRC_ENA                      0x0800  /* AUX_FRC_ENA */
+#define WM831X_AUX_FRC_ENA_MASK                 0x0800  /* AUX_FRC_ENA */
+#define WM831X_AUX_FRC_ENA_SHIFT                    11  /* AUX_FRC_ENA */
+#define WM831X_AUX_FRC_ENA_WIDTH                     1  /* AUX_FRC_ENA */
+#define WM831X_AUX_RATE_MASK                    0x003F  /* AUX_RATE - [5:0] */
+#define WM831X_AUX_RATE_SHIFT                        0  /* AUX_RATE - [5:0] */
+#define WM831X_AUX_RATE_WIDTH                        6  /* AUX_RATE - [5:0] */
+
+/*
+ * R16431 (0x402F) - AuxADC Source
+ */
+#define WM831X_AUX_CAL_SEL                      0x8000  /* AUX_CAL_SEL */
+#define WM831X_AUX_CAL_SEL_MASK                 0x8000  /* AUX_CAL_SEL */
+#define WM831X_AUX_CAL_SEL_SHIFT                    15  /* AUX_CAL_SEL */
+#define WM831X_AUX_CAL_SEL_WIDTH                     1  /* AUX_CAL_SEL */
+#define WM831X_AUX_BKUP_BATT_SEL                0x0400  /* AUX_BKUP_BATT_SEL */
+#define WM831X_AUX_BKUP_BATT_SEL_MASK           0x0400  /* AUX_BKUP_BATT_SEL */
+#define WM831X_AUX_BKUP_BATT_SEL_SHIFT              10  /* AUX_BKUP_BATT_SEL */
+#define WM831X_AUX_BKUP_BATT_SEL_WIDTH               1  /* AUX_BKUP_BATT_SEL */
+#define WM831X_AUX_WALL_SEL                     0x0200  /* AUX_WALL_SEL */
+#define WM831X_AUX_WALL_SEL_MASK                0x0200  /* AUX_WALL_SEL */
+#define WM831X_AUX_WALL_SEL_SHIFT                    9  /* AUX_WALL_SEL */
+#define WM831X_AUX_WALL_SEL_WIDTH                    1  /* AUX_WALL_SEL */
+#define WM831X_AUX_BATT_SEL                     0x0100  /* AUX_BATT_SEL */
+#define WM831X_AUX_BATT_SEL_MASK                0x0100  /* AUX_BATT_SEL */
+#define WM831X_AUX_BATT_SEL_SHIFT                    8  /* AUX_BATT_SEL */
+#define WM831X_AUX_BATT_SEL_WIDTH                    1  /* AUX_BATT_SEL */
+#define WM831X_AUX_USB_SEL                      0x0080  /* AUX_USB_SEL */
+#define WM831X_AUX_USB_SEL_MASK                 0x0080  /* AUX_USB_SEL */
+#define WM831X_AUX_USB_SEL_SHIFT                     7  /* AUX_USB_SEL */
+#define WM831X_AUX_USB_SEL_WIDTH                     1  /* AUX_USB_SEL */
+#define WM831X_AUX_SYSVDD_SEL                   0x0040  /* AUX_SYSVDD_SEL */
+#define WM831X_AUX_SYSVDD_SEL_MASK              0x0040  /* AUX_SYSVDD_SEL */
+#define WM831X_AUX_SYSVDD_SEL_SHIFT                  6  /* AUX_SYSVDD_SEL */
+#define WM831X_AUX_SYSVDD_SEL_WIDTH                  1  /* AUX_SYSVDD_SEL */
+#define WM831X_AUX_BATT_TEMP_SEL                0x0020  /* AUX_BATT_TEMP_SEL */
+#define WM831X_AUX_BATT_TEMP_SEL_MASK           0x0020  /* AUX_BATT_TEMP_SEL */
+#define WM831X_AUX_BATT_TEMP_SEL_SHIFT               5  /* AUX_BATT_TEMP_SEL */
+#define WM831X_AUX_BATT_TEMP_SEL_WIDTH               1  /* AUX_BATT_TEMP_SEL */
+#define WM831X_AUX_CHIP_TEMP_SEL                0x0010  /* AUX_CHIP_TEMP_SEL */
+#define WM831X_AUX_CHIP_TEMP_SEL_MASK           0x0010  /* AUX_CHIP_TEMP_SEL */
+#define WM831X_AUX_CHIP_TEMP_SEL_SHIFT               4  /* AUX_CHIP_TEMP_SEL */
+#define WM831X_AUX_CHIP_TEMP_SEL_WIDTH               1  /* AUX_CHIP_TEMP_SEL */
+#define WM831X_AUX_AUX4_SEL                     0x0008  /* AUX_AUX4_SEL */
+#define WM831X_AUX_AUX4_SEL_MASK                0x0008  /* AUX_AUX4_SEL */
+#define WM831X_AUX_AUX4_SEL_SHIFT                    3  /* AUX_AUX4_SEL */
+#define WM831X_AUX_AUX4_SEL_WIDTH                    1  /* AUX_AUX4_SEL */
+#define WM831X_AUX_AUX3_SEL                     0x0004  /* AUX_AUX3_SEL */
+#define WM831X_AUX_AUX3_SEL_MASK                0x0004  /* AUX_AUX3_SEL */
+#define WM831X_AUX_AUX3_SEL_SHIFT                    2  /* AUX_AUX3_SEL */
+#define WM831X_AUX_AUX3_SEL_WIDTH                    1  /* AUX_AUX3_SEL */
+#define WM831X_AUX_AUX2_SEL                     0x0002  /* AUX_AUX2_SEL */
+#define WM831X_AUX_AUX2_SEL_MASK                0x0002  /* AUX_AUX2_SEL */
+#define WM831X_AUX_AUX2_SEL_SHIFT                    1  /* AUX_AUX2_SEL */
+#define WM831X_AUX_AUX2_SEL_WIDTH                    1  /* AUX_AUX2_SEL */
+#define WM831X_AUX_AUX1_SEL                     0x0001  /* AUX_AUX1_SEL */
+#define WM831X_AUX_AUX1_SEL_MASK                0x0001  /* AUX_AUX1_SEL */
+#define WM831X_AUX_AUX1_SEL_SHIFT                    0  /* AUX_AUX1_SEL */
+#define WM831X_AUX_AUX1_SEL_WIDTH                    1  /* AUX_AUX1_SEL */
+
+/*
+ * R16432 (0x4030) - Comparator Control
+ */
+#define WM831X_DCOMP4_STS                       0x0800  /* DCOMP4_STS */
+#define WM831X_DCOMP4_STS_MASK                  0x0800  /* DCOMP4_STS */
+#define WM831X_DCOMP4_STS_SHIFT                     11  /* DCOMP4_STS */
+#define WM831X_DCOMP4_STS_WIDTH                      1  /* DCOMP4_STS */
+#define WM831X_DCOMP3_STS                       0x0400  /* DCOMP3_STS */
+#define WM831X_DCOMP3_STS_MASK                  0x0400  /* DCOMP3_STS */
+#define WM831X_DCOMP3_STS_SHIFT                     10  /* DCOMP3_STS */
+#define WM831X_DCOMP3_STS_WIDTH                      1  /* DCOMP3_STS */
+#define WM831X_DCOMP2_STS                       0x0200  /* DCOMP2_STS */
+#define WM831X_DCOMP2_STS_MASK                  0x0200  /* DCOMP2_STS */
+#define WM831X_DCOMP2_STS_SHIFT                      9  /* DCOMP2_STS */
+#define WM831X_DCOMP2_STS_WIDTH                      1  /* DCOMP2_STS */
+#define WM831X_DCOMP1_STS                       0x0100  /* DCOMP1_STS */
+#define WM831X_DCOMP1_STS_MASK                  0x0100  /* DCOMP1_STS */
+#define WM831X_DCOMP1_STS_SHIFT                      8  /* DCOMP1_STS */
+#define WM831X_DCOMP1_STS_WIDTH                      1  /* DCOMP1_STS */
+#define WM831X_DCMP4_ENA                        0x0008  /* DCMP4_ENA */
+#define WM831X_DCMP4_ENA_MASK                   0x0008  /* DCMP4_ENA */
+#define WM831X_DCMP4_ENA_SHIFT                       3  /* DCMP4_ENA */
+#define WM831X_DCMP4_ENA_WIDTH                       1  /* DCMP4_ENA */
+#define WM831X_DCMP3_ENA                        0x0004  /* DCMP3_ENA */
+#define WM831X_DCMP3_ENA_MASK                   0x0004  /* DCMP3_ENA */
+#define WM831X_DCMP3_ENA_SHIFT                       2  /* DCMP3_ENA */
+#define WM831X_DCMP3_ENA_WIDTH                       1  /* DCMP3_ENA */
+#define WM831X_DCMP2_ENA                        0x0002  /* DCMP2_ENA */
+#define WM831X_DCMP2_ENA_MASK                   0x0002  /* DCMP2_ENA */
+#define WM831X_DCMP2_ENA_SHIFT                       1  /* DCMP2_ENA */
+#define WM831X_DCMP2_ENA_WIDTH                       1  /* DCMP2_ENA */
+#define WM831X_DCMP1_ENA                        0x0001  /* DCMP1_ENA */
+#define WM831X_DCMP1_ENA_MASK                   0x0001  /* DCMP1_ENA */
+#define WM831X_DCMP1_ENA_SHIFT                       0  /* DCMP1_ENA */
+#define WM831X_DCMP1_ENA_WIDTH                       1  /* DCMP1_ENA */
+
+/*
+ * R16433 (0x4031) - Comparator 1
+ */
+#define WM831X_DCMP1_SRC_MASK                   0xE000  /* DCMP1_SRC - [15:13] */
+#define WM831X_DCMP1_SRC_SHIFT                      13  /* DCMP1_SRC - [15:13] */
+#define WM831X_DCMP1_SRC_WIDTH                       3  /* DCMP1_SRC - [15:13] */
+#define WM831X_DCMP1_GT                         0x1000  /* DCMP1_GT */
+#define WM831X_DCMP1_GT_MASK                    0x1000  /* DCMP1_GT */
+#define WM831X_DCMP1_GT_SHIFT                       12  /* DCMP1_GT */
+#define WM831X_DCMP1_GT_WIDTH                        1  /* DCMP1_GT */
+#define WM831X_DCMP1_THR_MASK                   0x0FFF  /* DCMP1_THR - [11:0] */
+#define WM831X_DCMP1_THR_SHIFT                       0  /* DCMP1_THR - [11:0] */
+#define WM831X_DCMP1_THR_WIDTH                      12  /* DCMP1_THR - [11:0] */
+
+/*
+ * R16434 (0x4032) - Comparator 2
+ */
+#define WM831X_DCMP2_SRC_MASK                   0xE000  /* DCMP2_SRC - [15:13] */
+#define WM831X_DCMP2_SRC_SHIFT                      13  /* DCMP2_SRC - [15:13] */
+#define WM831X_DCMP2_SRC_WIDTH                       3  /* DCMP2_SRC - [15:13] */
+#define WM831X_DCMP2_GT                         0x1000  /* DCMP2_GT */
+#define WM831X_DCMP2_GT_MASK                    0x1000  /* DCMP2_GT */
+#define WM831X_DCMP2_GT_SHIFT                       12  /* DCMP2_GT */
+#define WM831X_DCMP2_GT_WIDTH                        1  /* DCMP2_GT */
+#define WM831X_DCMP2_THR_MASK                   0x0FFF  /* DCMP2_THR - [11:0] */
+#define WM831X_DCMP2_THR_SHIFT                       0  /* DCMP2_THR - [11:0] */
+#define WM831X_DCMP2_THR_WIDTH                      12  /* DCMP2_THR - [11:0] */
+
+/*
+ * R16435 (0x4033) - Comparator 3
+ */
+#define WM831X_DCMP3_SRC_MASK                   0xE000  /* DCMP3_SRC - [15:13] */
+#define WM831X_DCMP3_SRC_SHIFT                      13  /* DCMP3_SRC - [15:13] */
+#define WM831X_DCMP3_SRC_WIDTH                       3  /* DCMP3_SRC - [15:13] */
+#define WM831X_DCMP3_GT                         0x1000  /* DCMP3_GT */
+#define WM831X_DCMP3_GT_MASK                    0x1000  /* DCMP3_GT */
+#define WM831X_DCMP3_GT_SHIFT                       12  /* DCMP3_GT */
+#define WM831X_DCMP3_GT_WIDTH                        1  /* DCMP3_GT */
+#define WM831X_DCMP3_THR_MASK                   0x0FFF  /* DCMP3_THR - [11:0] */
+#define WM831X_DCMP3_THR_SHIFT                       0  /* DCMP3_THR - [11:0] */
+#define WM831X_DCMP3_THR_WIDTH                      12  /* DCMP3_THR - [11:0] */
+
+/*
+ * R16436 (0x4034) - Comparator 4
+ */
+#define WM831X_DCMP4_SRC_MASK                   0xE000  /* DCMP4_SRC - [15:13] */
+#define WM831X_DCMP4_SRC_SHIFT                      13  /* DCMP4_SRC - [15:13] */
+#define WM831X_DCMP4_SRC_WIDTH                       3  /* DCMP4_SRC - [15:13] */
+#define WM831X_DCMP4_GT                         0x1000  /* DCMP4_GT */
+#define WM831X_DCMP4_GT_MASK                    0x1000  /* DCMP4_GT */
+#define WM831X_DCMP4_GT_SHIFT                       12  /* DCMP4_GT */
+#define WM831X_DCMP4_GT_WIDTH                        1  /* DCMP4_GT */
+#define WM831X_DCMP4_THR_MASK                   0x0FFF  /* DCMP4_THR - [11:0] */
+#define WM831X_DCMP4_THR_SHIFT                       0  /* DCMP4_THR - [11:0] */
+#define WM831X_DCMP4_THR_WIDTH                      12  /* DCMP4_THR - [11:0] */
+
+#define WM831X_AUX_CAL_FACTOR  0xfff
+#define WM831X_AUX_CAL_NOMINAL 0x222
+
+enum wm831x_auxadc {
+	WM831X_AUX_CAL = 15,
+	WM831X_AUX_BKUP_BATT = 10,
+	WM831X_AUX_WALL = 9,
+	WM831X_AUX_BATT = 8,
+	WM831X_AUX_USB = 7,
+	WM831X_AUX_SYSVDD = 6,
+	WM831X_AUX_BATT_TEMP = 5,
+	WM831X_AUX_CHIP_TEMP = 4,
+	WM831X_AUX_AUX4 = 3,
+	WM831X_AUX_AUX3 = 2,
+	WM831X_AUX_AUX2 = 1,
+	WM831X_AUX_AUX1 = 0,
+};
+
+int wm831x_auxadc_read(struct wm831x *wm831x, enum wm831x_auxadc input);
+int wm831x_auxadc_read_uv(struct wm831x *wm831x, enum wm831x_auxadc input);
+
+#endif
diff --git a/include/linux/mfd/wm831x/core.h b/include/linux/mfd/wm831x/core.h
index b96c935..d7134df 100644
--- a/include/linux/mfd/wm831x/core.h
+++ b/include/linux/mfd/wm831x/core.h
@@ -234,6 +234,8 @@
 	unsigned int irq_base;
 	int irq_masks[5];
 
+	struct mutex auxadc_lock;
+
 	/* The WM831x has a security key blocking access to certain
 	 * registers.  The mutex is taken by the accessors for locking
 	 * and unlocking the security key, locked is used to fail