diff mbox

[4/8] power: Add an axp20x-usb-power driver

Message ID 1433885881-19809-5-git-send-email-hdegoede@redhat.com
State Needs Review / ACK, archived
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Commit Message

Hans de Goede June 9, 2015, 9:37 p.m. UTC 
This adds a driver for the usb power_supply bits of the axp20x PMICs.

I initially started writing my own driver, before coming aware of
Bruno Prémont's excellent earlier RFC with a driver for this.

My driver was lacking CURRENT_MAX and VOLTAGE_MIN support Bruno's
drvier has, so I've copied the code for those from his driver.

Note that the AC-power-supply and battery charger bits will need separate
drivers. Each one needs its own devictree child-node so that other
devicetree nodes can reference the right power-supply, and thus each one
will get its own mfd-cell / platform_device and platform-driver.

Cc: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 .../bindings/power_supply/axp20x_usb_power.txt     |  34 +++
 drivers/power/Kconfig                              |   7 +
 drivers/power/Makefile                             |   1 +
 drivers/power/axp20x_usb_power.c                   | 241 +++++++++++++++++++++
 include/linux/mfd/axp20x.h                         |  24 ++
 5 files changed, 307 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power_supply/axp20x_usb_power.txt
 create mode 100644 drivers/power/axp20x_usb_power.c

Comments

Lee Jones June 10, 2015, 7:29 a.m. UTC | #1 
On Tue, 09 Jun 2015, Hans de Goede wrote:

> This adds a driver for the usb power_supply bits of the axp20x PMICs.
> 
> I initially started writing my own driver, before coming aware of
> Bruno Prémont's excellent earlier RFC with a driver for this.
> 
> My driver was lacking CURRENT_MAX and VOLTAGE_MIN support Bruno's
> drvier has, so I've copied the code for those from his driver.
> 
> Note that the AC-power-supply and battery charger bits will need separate
> drivers. Each one needs its own devictree child-node so that other
> devicetree nodes can reference the right power-supply, and thus each one
> will get its own mfd-cell / platform_device and platform-driver.
> 
> Cc: Bruno Prémont <bonbons@linux-vserver.org>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  .../bindings/power_supply/axp20x_usb_power.txt     |  34 +++

This needs to be submitted in a seperate patch.

>  drivers/power/Kconfig                              |   7 +
>  drivers/power/Makefile                             |   1 +
>  drivers/power/axp20x_usb_power.c                   | 241 +++++++++++++++++++++
>  include/linux/mfd/axp20x.h                         |  24 ++
>  5 files changed, 307 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power_supply/axp20x_usb_power.txt
>  create mode 100644 drivers/power/axp20x_usb_power.c

[...]

> diff --git a/include/linux/mfd/axp20x.h b/include/linux/mfd/axp20x.h
> index f4290ae..d7adb2e 100644
> --- a/include/linux/mfd/axp20x.h
> +++ b/include/linux/mfd/axp20x.h
> @@ -11,6 +11,8 @@
>  #ifndef __LINUX_MFD_AXP20X_H
>  #define __LINUX_MFD_AXP20X_H
>  
> +#include <linux/regmap.h>
> +
>  enum {
>  	AXP202_ID = 0,
>  	AXP209_ID,
> @@ -366,4 +368,26 @@ struct axp20x_fg_pdata {
>  	int thermistor_curve[MAX_THERM_CURVE_SIZE][2];
>  };
>  
> +/* generic helper function for reading 9-16 bit wide regs */
> +static inline int axp20x_read_16bit(struct regmap *regmap,

This is only used twice and only in one file.

Do you know of any other uses of this call that will be upstreamed
shortly?

> +				    unsigned int reg, unsigned int width)

The function name is a bit misleading.

> +{
> +	unsigned int v, raw;
> +	int r;

'v' and 'r' are not good variable names.

> +	r = regmap_read(regmap, reg, &v);
> +	if (r)
> +		return r;
> +
> +	raw = v << (width - 8);

So 'reg' is expected to be top end loaded?

E.g A value of say 0x0101 (257) in 9 bits will look like this:

reg          reg + 1
1000 0000b   0000 0001b

> +	r = regmap_read(regmap, reg + 1, &v);
> +	if (r)
> +		return r;
> +
> +	raw |= v;
> +
> +	return raw;
> +}
> +
>  #endif /* __LINUX_MFD_AXP20X_H */
Hans de Goede June 10, 2015, 9:22 a.m. UTC | #2 
Hi,

Thanks for the quick review I'll do a v2 addressing your concerns soonish.

On 10-06-15 09:29, Lee Jones wrote:
> On Tue, 09 Jun 2015, Hans de Goede wrote:
>
>> This adds a driver for the usb power_supply bits of the axp20x PMICs.
>>
>> I initially started writing my own driver, before coming aware of
>> Bruno Prémont's excellent earlier RFC with a driver for this.
>>
>> My driver was lacking CURRENT_MAX and VOLTAGE_MIN support Bruno's
>> drvier has, so I've copied the code for those from his driver.
>>
>> Note that the AC-power-supply and battery charger bits will need separate
>> drivers. Each one needs its own devictree child-node so that other
>> devicetree nodes can reference the right power-supply, and thus each one
>> will get its own mfd-cell / platform_device and platform-driver.
>>
>> Cc: Bruno Prémont <bonbons@linux-vserver.org>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
>>   .../bindings/power_supply/axp20x_usb_power.txt     |  34 +++
>
> This needs to be submitted in a seperate patch.

Ok.

>
>>   drivers/power/Kconfig                              |   7 +
>>   drivers/power/Makefile                             |   1 +
>>   drivers/power/axp20x_usb_power.c                   | 241 +++++++++++++++++++++
>>   include/linux/mfd/axp20x.h                         |  24 ++
>>   5 files changed, 307 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/power_supply/axp20x_usb_power.txt
>>   create mode 100644 drivers/power/axp20x_usb_power.c
>
> [...]
>
>> diff --git a/include/linux/mfd/axp20x.h b/include/linux/mfd/axp20x.h
>> index f4290ae..d7adb2e 100644
>> --- a/include/linux/mfd/axp20x.h
>> +++ b/include/linux/mfd/axp20x.h
>> @@ -11,6 +11,8 @@
>>   #ifndef __LINUX_MFD_AXP20X_H
>>   #define __LINUX_MFD_AXP20X_H
>>
>> +#include <linux/regmap.h>
>> +
>>   enum {
>>   	AXP202_ID = 0,
>>   	AXP209_ID,
>> @@ -366,4 +368,26 @@ struct axp20x_fg_pdata {
>>   	int thermistor_curve[MAX_THERM_CURVE_SIZE][2];
>>   };
>>
>> +/* generic helper function for reading 9-16 bit wide regs */
>> +static inline int axp20x_read_16bit(struct regmap *regmap,
>
> This is only used twice and only in one file.
>
> Do you know of any other uses of this call that will be upstreamed
> shortly?

Yes I plan to write drivers for the other 3 power_supply class
cells (ac-power, battery-charger, rtc-bat-charger) in the axp209,
and most of those need the same helper which I why I put it here.

>
>> +				    unsigned int reg, unsigned int width)
>
> The function name is a bit misleading.

How about: axp20x_read_multibyte_reg ?

>
>> +{
>> +	unsigned int v, raw;
>> +	int r;
>
> 'v' and 'r' are not good variable names.
>
>> +	r = regmap_read(regmap, reg, &v);
>> +	if (r)
>> +		return r;
>> +
>> +	raw = v << (width - 8);
>
> So 'reg' is expected to be top end loaded?
>
> E.g A value of say 0x0101 (257) in 9 bits will look like this:
>
> reg          reg + 1
> 1000 0000b   0000 0001b

Yes, I guess this was done so that you can get all the 8 msb-s
in a single read if you do not care about the lsb-s.

>
>> +	r = regmap_read(regmap, reg + 1, &v);
>> +	if (r)
>> +		return r;
>> +
>> +	raw |= v;
>> +
>> +	return raw;
>> +}
>> +
>>   #endif /* __LINUX_MFD_AXP20X_H */
>

Regards,

Hans
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Lee Jones June 10, 2015, 9:34 a.m. UTC | #3 
On Wed, 10 Jun 2015, Hans de Goede wrote:

> Hi,
> 
> Thanks for the quick review I'll do a v2 addressing your concerns soonish.
> 
> On 10-06-15 09:29, Lee Jones wrote:
> >On Tue, 09 Jun 2015, Hans de Goede wrote:
> >
> >>This adds a driver for the usb power_supply bits of the axp20x PMICs.
> >>
> >>I initially started writing my own driver, before coming aware of
> >>Bruno Prémont's excellent earlier RFC with a driver for this.
> >>
> >>My driver was lacking CURRENT_MAX and VOLTAGE_MIN support Bruno's
> >>drvier has, so I've copied the code for those from his driver.
> >>
> >>Note that the AC-power-supply and battery charger bits will need separate
> >>drivers. Each one needs its own devictree child-node so that other
> >>devicetree nodes can reference the right power-supply, and thus each one
> >>will get its own mfd-cell / platform_device and platform-driver.
> >>
> >>Cc: Bruno Prémont <bonbons@linux-vserver.org>
> >>Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> >>---
> >>  .../bindings/power_supply/axp20x_usb_power.txt     |  34 +++
> >
> >This needs to be submitted in a seperate patch.
> 
> Ok.
> 
> >
> >>  drivers/power/Kconfig                              |   7 +
> >>  drivers/power/Makefile                             |   1 +
> >>  drivers/power/axp20x_usb_power.c                   | 241 +++++++++++++++++++++
> >>  include/linux/mfd/axp20x.h                         |  24 ++
> >>  5 files changed, 307 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/power_supply/axp20x_usb_power.txt
> >>  create mode 100644 drivers/power/axp20x_usb_power.c
> >
> >[...]
> >
> >>diff --git a/include/linux/mfd/axp20x.h b/include/linux/mfd/axp20x.h
> >>index f4290ae..d7adb2e 100644
> >>--- a/include/linux/mfd/axp20x.h
> >>+++ b/include/linux/mfd/axp20x.h
> >>@@ -11,6 +11,8 @@
> >>  #ifndef __LINUX_MFD_AXP20X_H
> >>  #define __LINUX_MFD_AXP20X_H
> >>
> >>+#include <linux/regmap.h>
> >>+
> >>  enum {
> >>  	AXP202_ID = 0,
> >>  	AXP209_ID,
> >>@@ -366,4 +368,26 @@ struct axp20x_fg_pdata {
> >>  	int thermistor_curve[MAX_THERM_CURVE_SIZE][2];
> >>  };
> >>
> >>+/* generic helper function for reading 9-16 bit wide regs */
> >>+static inline int axp20x_read_16bit(struct regmap *regmap,
> >
> >This is only used twice and only in one file.
> >
> >Do you know of any other uses of this call that will be upstreamed
> >shortly?
> 
> Yes I plan to write drivers for the other 3 power_supply class
> cells (ac-power, battery-charger, rtc-bat-charger) in the axp209,
> and most of those need the same helper which I why I put it here.

Okay.

> >>+				    unsigned int reg, unsigned int width)
> >
> >The function name is a bit misleading.
> 
> How about: axp20x_read_multibyte_reg ?

axp20x_read_variable_width() ?

> >>+{
> >>+	unsigned int v, raw;
> >>+	int r;
> >
> >'v' and 'r' are not good variable names.
> >
> >>+	r = regmap_read(regmap, reg, &v);
> >>+	if (r)
> >>+		return r;
> >>+
> >>+	raw = v << (width - 8);
> >
> >So 'reg' is expected to be top end loaded?
> >
> >E.g A value of say 0x0101 (257) in 9 bits will look like this:
> >
> >reg          reg + 1
> >1000 0000b   0000 0001b
> 
> Yes, I guess this was done so that you can get all the 8 msb-s
> in a single read if you do not care about the lsb-s.

Odd, but okay.

> >>+	r = regmap_read(regmap, reg + 1, &v);
> >>+	if (r)
> >>+		return r;
> >>+
> >>+	raw |= v;
> >>+
> >>+	return raw;
> >>+}
> >>+
> >>  #endif /* __LINUX_MFD_AXP20X_H */
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/power_supply/axp20x_usb_power.txt b/Documentation/devicetree/bindings/power_supply/axp20x_usb_power.txt
new file mode 100644
index 0000000..a84d801
--- /dev/null
+++ b/Documentation/devicetree/bindings/power_supply/axp20x_usb_power.txt
@@ -0,0 +1,34 @@ 
+AXP20x USB power supply
+
+Required Properties:
+-compatible: "x-powers,axp202-usb-power-supply"
+
+This node is a subnode of the axp20x PMIC.
+
+Example:
+
+axp209: pmic@34 {
+	compatible = "x-powers,axp209";
+	reg = <0x34>;
+	interrupt-parent = <&nmi_intc>;
+	interrupts = <0 IRQ_TYPE_LEVEL_LOW>;
+	interrupt-controller;
+	#interrupt-cells = <1>;
+
+	regulators {
+		x-powers,dcdc-freq = <1500>;
+
+		vdd_cpu: dcdc2 {
+			regulator-always-on;
+			regulator-min-microvolt = <1000000>;
+			regulator-max-microvolt = <1450000>;
+			regulator-name = "vdd-cpu";
+		};
+
+		...
+	};
+
+	usb_power_supply: usb_power_supply {
+		compatible = "x-powers,axp202-usb-power-supply";
+	};
+};
diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 4091fb0..1fee60c 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -439,6 +439,13 @@  config BATTERY_RT5033
 	  The fuelgauge calculates and determines the battery state of charge
 	  according to battery open circuit voltage.
 
+config AXP20X_POWER
+	tristate "AXP20x power supply driver"
+	depends on MFD_AXP20X
+	help
+	  This driver provides support for the power supply features of
+	  AXP20x PMIC.
+
 source "drivers/power/reset/Kconfig"
 
 endif # POWER_SUPPLY
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index b7b0181..ae0f27d 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -9,6 +9,7 @@  obj-$(CONFIG_GENERIC_ADC_BATTERY)	+= generic-adc-battery.o
 
 obj-$(CONFIG_PDA_POWER)		+= pda_power.o
 obj-$(CONFIG_APM_POWER)		+= apm_power.o
+obj-$(CONFIG_AXP20X_POWER)	+= axp20x_usb_power.o
 obj-$(CONFIG_MAX8925_POWER)	+= max8925_power.o
 obj-$(CONFIG_WM831X_BACKUP)	+= wm831x_backup.o
 obj-$(CONFIG_WM831X_POWER)	+= wm831x_power.o
diff --git a/drivers/power/axp20x_usb_power.c b/drivers/power/axp20x_usb_power.c
new file mode 100644
index 0000000..4be4c8b
--- /dev/null
+++ b/drivers/power/axp20x_usb_power.c
@@ -0,0 +1,241 @@ 
+/*
+ * AXP20x PMIC USB power supply status driver
+ *
+ * Copyright (C) 2015 Hans de Goede <hdegoede@redhat.com>
+ * Copyright (C) 2014 Bruno Prémont <bonbons@linux-vserver.org>
+ *
+ * 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.
+ */
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/axp20x.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define DRVNAME "axp20x-usb-power-supply"
+
+#define AXP20X_PWR_STATUS_VBUS_PRESENT	BIT(5)
+#define AXP20X_PWR_STATUS_VBUS_USED	BIT(4)
+
+#define AXP20X_USB_STATUS_VBUS_VALID	BIT(2)
+
+#define AXP20X_VBUS_VHOLD_uV(b)		(4000000 + (((b) >> 3) & 7) * 100000)
+#define AXP20X_VBUS_CLIMIT_MASK 	3
+#define AXP20X_VBUC_CLIMIT_900mA	0
+#define AXP20X_VBUC_CLIMIT_500mA	1
+#define AXP20X_VBUC_CLIMIT_100mA	2
+#define AXP20X_VBUC_CLIMIT_NONE		3
+
+#define AXP20X_ADC_EN1_VBUS_CURR	BIT(2)
+#define AXP20X_ADC_EN1_VBUS_VOLT	BIT(3)
+
+#define AXP20X_VBUS_MON_VBUS_VALID	BIT(3)
+
+struct axp20x_usb_power {
+	struct regmap *regmap;
+	struct power_supply *supply;
+};
+
+static irqreturn_t axp20x_usb_power_irq(int irq, void *devid)
+{
+	struct axp20x_usb_power *power = devid;
+
+	power_supply_changed(power->supply);
+
+	return IRQ_HANDLED;
+}
+
+static int axp20x_usb_power_get_property(struct power_supply *psy,
+	enum power_supply_property psp, union power_supply_propval *val)
+{
+	struct axp20x_usb_power *power = power_supply_get_drvdata(psy);
+	unsigned int input, v;
+	int r;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_MIN:
+		r = regmap_read(power->regmap, AXP20X_VBUS_IPSOUT_MGMT, &v);
+		if (r)
+			return r;
+
+		val->intval = AXP20X_VBUS_VHOLD_uV(v);
+		return 0;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		r = axp20x_read_16bit(power->regmap, AXP20X_VBUS_V_ADC_H, 12);
+		if (r < 0)
+			return r;
+
+		val->intval = r * 1700; /* 1 step = 1.7 mV */
+		return 0;
+	case POWER_SUPPLY_PROP_CURRENT_MAX:
+		r = regmap_read(power->regmap, AXP20X_VBUS_IPSOUT_MGMT, &v);
+		if (r)
+			return r;
+
+		switch (v & AXP20X_VBUS_CLIMIT_MASK) {
+		case AXP20X_VBUC_CLIMIT_100mA:
+			val->intval = 100000;
+			break;
+		case AXP20X_VBUC_CLIMIT_500mA:
+			val->intval = 500000;
+			break;
+		case AXP20X_VBUC_CLIMIT_900mA:
+			val->intval = 900000;
+			break;
+		case AXP20X_VBUC_CLIMIT_NONE:
+			val->intval = -1;
+			break;
+		}
+		return 0;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		r = axp20x_read_16bit(power->regmap, AXP20X_VBUS_I_ADC_H, 12);
+		if (r < 0)
+			return r;
+
+		val->intval = r * 375; /* 1 step = 0.375 mA */
+		return 0;
+	default:
+		break;
+	}
+
+	/* All the properties below need the input-status reg value */
+	r = regmap_read(power->regmap, AXP20X_PWR_INPUT_STATUS, &input);
+	if (r)
+		return r;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_HEALTH:
+		if (!(input & AXP20X_PWR_STATUS_VBUS_PRESENT)) {
+			val->intval = POWER_SUPPLY_HEALTH_UNKNOWN;
+			break;
+		}
+
+		r = regmap_read(power->regmap, AXP20X_USB_OTG_STATUS, &v);
+		if (r)
+			return r;
+
+		if (!(v & AXP20X_USB_STATUS_VBUS_VALID)) {
+			val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
+			break;
+		}
+
+		val->intval = POWER_SUPPLY_HEALTH_GOOD;
+		break;
+	case POWER_SUPPLY_PROP_PRESENT:
+		val->intval = !!(input & AXP20X_PWR_STATUS_VBUS_PRESENT);
+		break;
+	case POWER_SUPPLY_PROP_ONLINE:
+		val->intval = !!(input & AXP20X_PWR_STATUS_VBUS_USED);
+		break;
+	default:
+		return -EINVAL;
+	}
+	
+	return 0;
+}
+
+static enum power_supply_property axp20x_usb_power_properties[] = {
+	POWER_SUPPLY_PROP_HEALTH,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_ONLINE,
+	POWER_SUPPLY_PROP_VOLTAGE_MIN,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_MAX,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+};
+
+static const struct power_supply_desc axp20x_usb_power_desc = {
+	.name = "axp20x-usb",
+	.type = POWER_SUPPLY_TYPE_USB,
+	.properties = axp20x_usb_power_properties,
+	.num_properties = ARRAY_SIZE(axp20x_usb_power_properties),
+	.get_property = axp20x_usb_power_get_property,
+};
+
+static int axp20x_usb_power_probe(struct platform_device *pdev)
+{
+	struct axp20x_dev *axp20x = dev_get_drvdata(pdev->dev.parent);
+	struct power_supply_config psy_cfg = {};
+	struct axp20x_usb_power *power;
+	const char *irq_names[] = { "VBUS_PLUGIN", "VBUS_REMOVAL",
+				    "VBUS_VALID", "VBUS_NOT_VALID" };
+	int i, irq, r;
+
+	if (!of_device_is_available(pdev->dev.of_node))
+		return -ENODEV;
+
+	power = devm_kzalloc(&pdev->dev, sizeof(*power), GFP_KERNEL);
+	if (!power)
+		return -ENOMEM;
+
+	power->regmap = axp20x->regmap;
+
+	/* Enable vbus valid checking */
+	r = regmap_update_bits(power->regmap, AXP20X_VBUS_MON,
+		    AXP20X_VBUS_MON_VBUS_VALID, AXP20X_VBUS_MON_VBUS_VALID);
+	if (r)
+		return r;
+
+	/* Enable vbus voltage and current measurement */
+	r = regmap_update_bits(power->regmap, AXP20X_ADC_EN1,
+			AXP20X_ADC_EN1_VBUS_CURR | AXP20X_ADC_EN1_VBUS_VOLT,
+			AXP20X_ADC_EN1_VBUS_CURR | AXP20X_ADC_EN1_VBUS_VOLT);
+	if (r)
+		return r;
+
+	psy_cfg.of_node = pdev->dev.of_node;
+	psy_cfg.drv_data = power;
+
+	power->supply = devm_power_supply_register(&pdev->dev,
+					&axp20x_usb_power_desc, &psy_cfg);
+	if (IS_ERR(power->supply))
+		return PTR_ERR(power->supply);
+
+	/* Request irqs after registering, as irqs may trigger immediately */
+	for (i = 0; i < ARRAY_SIZE(irq_names); i++) {
+		irq = platform_get_irq_byname(pdev, irq_names[i]);
+		if (irq < 0) {
+			dev_warn(&pdev->dev, "No IRQ for %s: %d\n",
+				 irq_names[i], irq);
+			continue;
+		}
+		irq = regmap_irq_get_virq(axp20x->regmap_irqc, irq);
+		r = devm_request_any_context_irq(&pdev->dev, irq,
+				axp20x_usb_power_irq, 0, DRVNAME, power);
+		if (r < 0)
+			dev_warn(&pdev->dev, "Error requesting %s IRQ: %d\n",
+				 irq_names[i], r);
+	}
+
+	return 0;
+}
+
+static const struct of_device_id axp20x_usb_power_match[] = {
+	{ .compatible = "x-powers,axp202-usb-power-supply" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, axp20x_usb_power_match);
+
+static struct platform_driver axp20x_usb_power_driver = {
+	.probe = axp20x_usb_power_probe,
+	.driver = {
+		.name = DRVNAME,
+		.of_match_table = axp20x_usb_power_match,
+	},
+};
+
+module_platform_driver(axp20x_usb_power_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("AXP20x PMIC USB power supply status driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/axp20x.h b/include/linux/mfd/axp20x.h
index f4290ae..d7adb2e 100644
--- a/include/linux/mfd/axp20x.h
+++ b/include/linux/mfd/axp20x.h
@@ -11,6 +11,8 @@ 
 #ifndef __LINUX_MFD_AXP20X_H
 #define __LINUX_MFD_AXP20X_H
 
+#include <linux/regmap.h>
+
 enum {
 	AXP202_ID = 0,
 	AXP209_ID,
@@ -366,4 +368,26 @@  struct axp20x_fg_pdata {
 	int thermistor_curve[MAX_THERM_CURVE_SIZE][2];
 };
 
+/* generic helper function for reading 9-16 bit wide regs */
+static inline int axp20x_read_16bit(struct regmap *regmap,
+				    unsigned int reg, unsigned int width)
+{
+	unsigned int v, raw;
+	int r;
+
+	r = regmap_read(regmap, reg, &v);
+	if (r)
+		return r;
+
+	raw = v << (width - 8);
+
+	r = regmap_read(regmap, reg + 1, &v);
+	if (r)
+		return r;
+
+	raw |= v;
+
+	return raw;
+}
+
 #endif /* __LINUX_MFD_AXP20X_H */