power: Add an axp20x-usb-power driver

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>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/Kconfig

@@ -472,6 +472,13 @@ config CHARGER_RT9455
 	help
 	  Say Y to enable support for Richtek RT9455 battery charger.
 
+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

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

drivers/power/axp20x_usb_power.c

@@ -0,0 +1,248 @@
+/*
+ * 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 ret;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_MIN:
+		ret = regmap_read(power->regmap, AXP20X_VBUS_IPSOUT_MGMT, &v);
+		if (ret)
+			return ret;
+
+		val->intval = AXP20X_VBUS_VHOLD_uV(v);
+		return 0;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = axp20x_read_variable_width(power->regmap,
+						 AXP20X_VBUS_V_ADC_H, 12);
+		if (ret < 0)
+			return ret;
+
+		val->intval = ret * 1700; /* 1 step = 1.7 mV */
+		return 0;
+	case POWER_SUPPLY_PROP_CURRENT_MAX:
+		ret = regmap_read(power->regmap, AXP20X_VBUS_IPSOUT_MGMT, &v);
+		if (ret)
+			return ret;
+
+		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:
+		ret = axp20x_read_variable_width(power->regmap,
+						 AXP20X_VBUS_I_ADC_H, 12);
+		if (ret < 0)
+			return ret;
+
+		val->intval = ret * 375; /* 1 step = 0.375 mA */
+		return 0;
+	default:
+		break;
+	}
+
+	/* All the properties below need the input-status reg value */
+	ret = regmap_read(power->regmap, AXP20X_PWR_INPUT_STATUS, &input);
+	if (ret)
+		return ret;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_HEALTH:
+		if (!(input & AXP20X_PWR_STATUS_VBUS_PRESENT)) {
+			val->intval = POWER_SUPPLY_HEALTH_UNKNOWN;
+			break;
+		}
+
+		ret = regmap_read(power->regmap, AXP20X_USB_OTG_STATUS, &v);
+		if (ret)
+			return ret;
+
+		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;
+	static const char * const irq_names[] = { "VBUS_PLUGIN",
+		"VBUS_REMOVAL", "VBUS_VALID", "VBUS_NOT_VALID" };
+	int i, irq, ret;
+
+	if (!of_device_is_available(pdev->dev.of_node))
+		return -ENODEV;
+
+	if (!axp20x) {
+		dev_err(&pdev->dev, "Parent drvdata not set\n");
+		return -EINVAL;
+	}
+
+	power = devm_kzalloc(&pdev->dev, sizeof(*power), GFP_KERNEL);
+	if (!power)
+		return -ENOMEM;
+
+	power->regmap = axp20x->regmap;
+
+	/* Enable vbus valid checking */
+	ret = regmap_update_bits(power->regmap, AXP20X_VBUS_MON,
+		    AXP20X_VBUS_MON_VBUS_VALID, AXP20X_VBUS_MON_VBUS_VALID);
+	if (ret)
+		return ret;
+
+	/* Enable vbus voltage and current measurement */
+	ret = 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 (ret)
+		return ret;
+
+	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);
+		ret = devm_request_any_context_irq(&pdev->dev, irq,
+				axp20x_usb_power_irq, 0, DRVNAME, power);
+		if (ret < 0)
+			dev_warn(&pdev->dev, "Error requesting %s IRQ: %d\n",
+				 irq_names[i], ret);
+	}
+
+	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");

include/linux/mfd/axp20x.h

@@ -11,6 +11,8 @@
 #ifndef __LINUX_MFD_AXP20X_H
 #define __LINUX_MFD_AXP20X_H
 
+#include <linux/regmap.h>
+
 enum {
 	AXP152_ID = 0,
 	AXP202_ID,
@@ -438,4 +440,26 @@ struct axp288_extcon_pdata {
 	struct gpio_desc *gpio_mux_cntl;
 };
 
+/* generic helper function for reading 9-16 bit wide regs */
+static inline int axp20x_read_variable_width(struct regmap *regmap,
+	unsigned int reg, unsigned int width)
+{
+	unsigned int reg_val, result;
+	int err;
+
+	err = regmap_read(regmap, reg, &reg_val);
+	if (err)
+		return err;
+
+	result = reg_val << (width - 8);
+
+	err = regmap_read(regmap, reg + 1, &reg_val);
+	if (err)
+		return err;
+
+	result |= reg_val;
+
+	return result;
+}
+
 #endif /* __LINUX_MFD_AXP20X_H */