power: introduce the charger uclass

chargers have set current, get current, and get status operations.
They control the charging state of a battery. Typically
a charger, extcon, and battery driver would work in tandem:

* extcon detects the cable's maximum current (if a cable is attached).
* battery detects state of charge (i.e. does the battery need
charging?).
* charger controls current in order to allow the battery to charge.

Author: fourkbomb

Makefile

@@ -666,6 +666,7 @@ libs-y += drivers/net/
 libs-y += drivers/net/phy/
 libs-y += drivers/pci/
 libs-y += drivers/power/ \
+	drivers/power/charger/ \
 	drivers/power/domain/ \
 	drivers/power/fuel_gauge/ \
 	drivers/power/mfd/ \

drivers/power/Kconfig

@@ -2,6 +2,8 @@ menu "Power"
 
 source "drivers/power/battery/Kconfig"
 
+source "drivers/power/charger/Kconfig"
+
 source "drivers/power/domain/Kconfig"
 
 source "drivers/power/pmic/Kconfig"

drivers/power/charger/Kconfig

@@ -0,0 +1,5 @@
+config DM_CHARGER
+	bool "Enable Driver Model for charger drivers (UCLASS_CHARGER)"
+	depends on DM
+	---help---
+	This config enables driver model charger support.

drivers/power/charger/Makefile

@@ -0,0 +1,8 @@
+#
+# Copyright (C) 2018 Simon Shields <simon@lineageos.org>
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-$(CONFIG_DM_CHARGER) += charger-uclass.o
+

drivers/power/charger/charger-uclass.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2018 Simon Shields <simon@lineageos.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <dm.h>
+#include <dm/uclass-internal.h>
+#include <power/charger.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int charger_get(const char *devname, struct udevice **devp)
+{
+	return uclass_get_device_by_name(UCLASS_CHARGER, devname, devp);
+}
+
+int charger_set_current(struct udevice *dev, unsigned int microamps)
+{
+	const struct dm_charger_ops *ops = dev_get_driver_ops(dev);
+
+	if (!ops || !ops->set_current)
+		return -ENOSYS;
+
+	return ops->set_current(dev, microamps);
+}
+
+int charger_get_current(struct udevice *dev)
+{
+	const struct dm_charger_ops *ops = dev_get_driver_ops(dev);
+
+	if (!ops || !ops->get_current)
+		return -ENOSYS;
+
+	return ops->get_current(dev);
+}
+
+int charger_get_status(struct udevice *dev)
+{
+	const struct dm_charger_ops *ops = dev_get_driver_ops(dev);
+
+	if (!ops || !ops->get_status)
+		return -ENOSYS;
+
+	return ops->get_status(dev);
+}
+
+
+UCLASS_DRIVER(charger) = {
+	.id = UCLASS_CHARGER,
+	.name = "charger",
+};

include/dm/uclass-id.h

@@ -30,6 +30,7 @@ enum uclass_id {
 	UCLASS_AHCI,		/* SATA disk controller */
 	UCLASS_BATTERY,		/* Battery */
 	UCLASS_BLK,		/* Block device */
+	UCLASS_CHARGER,		/* Charger */
 	UCLASS_CLK,		/* Clock source, e.g. used by peripherals */
 	UCLASS_CPU,		/* CPU, typically part of an SoC */
 	UCLASS_CROS_EC,		/* Chrome OS EC */

include/power/charger.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2018 Simon Shields <simon@lineageos.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+enum charger_state {
+	CHARGE_STATE_UNKNOWN = 0,
+	CHARGE_STATE_CHARGING = 1, /* charging normally */
+	CHARGE_STATE_FULL = 2, /* not charging - battery full */
+	CHARGE_STATE_NOT_CHARGING = 3, /* not charging - some other reason */
+	CHARGE_STATE_DISCHARGING = 4, /* discharging */
+};
+
+struct dm_charger_ops {
+	/**
+	 * Get the charge current of the charger.
+	 * Some devices may return the maximum charge current rather than the current charge current.
+	 * @dev		- charger device.
+	 * @return -errno on error, charge current in uA.
+	 */
+	int (*get_current)(struct udevice *dev);
+	/**
+	 * Set the maximum charge current for the charger. A current of zero will disable charging.
+	 * @dev		- charger device
+	 * @return	-errno on error, 0 otherwise.
+	 */
+	int (*set_current)(struct udevice *dev, unsigned int microamps);
+	/**
+	 * Get current charging state.
+	 * @dev		- charger device
+	 * @return	-errno on error, enum charger_state otherwise.
+	 */
+	int (*get_status)(struct udevice *dev);
+};
+
+int charger_get(const char *devname, struct udevice **devp);
+int charger_get_current(struct udevice *dev);
+int charger_set_current(struct udevice *dev, unsigned int microamps);
+int charger_get_status(struct udevice *dev);