Date:   Thu, 31 Jan 2019 10:23:03 +0200
From:   Stefan Mavrodiev <stefan@...mex.com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>, Chen-Yu Tsai <wens@...e.org>,
        linux-kernel@...r.kernel.org (open list),
        linux-leds@...r.kernel.org (open list:LED SUBSYSTEM)
Cc:     Stefan Mavrodiev <stefan@...mex.com>
Subject: [PATCH 1/5] leds: Add support for AXP20X CHGLED

Most of AXP20x PMIC chips have built-in battery charger with LED indicator.
The LED can be controlled ether by the charger or manually by a register.

The default is (except for AXP209) manual control, which makes this LED
useless, since there is no device driver.

The driver rely on AXP20X MFD driver.

Signed-off-by: Stefan Mavrodiev <stefan@...mex.com>
---
 drivers/leds/Kconfig       |  10 ++
 drivers/leds/Makefile      |   1 +
 drivers/leds/leds-axp20x.c | 283 +++++++++++++++++++++++++++++++++++++
 3 files changed, 294 insertions(+)
 create mode 100644 drivers/leds/leds-axp20x.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index a72f97fca57b..82dce9063d41 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -766,6 +766,16 @@ config LEDS_NIC78BX
 	  To compile this driver as a module, choose M here: the module
 	  will be called leds-nic78bx.
 
+config LEDS_AXP20X
+	tristate "LED support for X-Powers PMICs"
+	depends on MFD_AXP20X
+	help
+	  This option enables support for CHGLED found on most of X-Powers
+	  PMICs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called leds-axp20x.
+
 comment "LED Triggers"
 source "drivers/leds/trigger/Kconfig"
 
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 4c1b0054f379..d3fb76e119d8 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -79,6 +79,7 @@ obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
 obj-$(CONFIG_LEDS_LM3692X)		+= leds-lm3692x.o
 obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
 obj-$(CONFIG_LEDS_LM3601X)		+= leds-lm3601x.o
+obj-$(CONFIG_LEDS_AXP20X)		+= leds-axp20x.o
 
 # LED SPI Drivers
 obj-$(CONFIG_LEDS_CR0014114)		+= leds-cr0014114.o
diff --git a/drivers/leds/leds-axp20x.c b/drivers/leds/leds-axp20x.c
new file mode 100644
index 000000000000..9c03410833a3
--- /dev/null
+++ b/drivers/leds/leds-axp20x.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright 2019 Stefan Mavrodiev <stefan@...mex.com>
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#include <linux/mfd/axp20x.h>
+
+#define AXP20X_CHGLED_CTRL_REG		AXP20X_OFF_CTRL
+#define AXP20X_CHGLED_FUNC_MASK			GENMASK(5, 4)
+#define AXP20X_CHGLED_FUNC_OFF			(0 << 4)
+#define AXP20X_CHGLED_FUNC_1HZ			(1 << 4)
+#define AXP20X_CHGLED_FUNC_4HZ			(2 << 4)
+#define AXP20X_CHGLED_FUNC_FULL			(3 << 4)
+#define AXP20X_CHGLED_CTRL_MASK			BIT(3)
+#define AXP20X_CHGLED_CTRL_MANUAL		0
+#define AXP20X_CHGLED_CTRL_CHARGER		1
+#define AXP20X_CHGLED_CTRL(_ctrl)		(_ctrl << 3)
+
+#define AXP20X_CHGLED_MODE_REG		AXP20X_CHRG_CTRL2
+#define AXP20X_CHGLED_MODE_MASK			BIT(4)
+#define AXP20X_CHGLED_MODE_A			0
+#define AXP20X_CHGLED_MODE_B			1
+#define AXP20X_CHGLED_MODE(_mode)		(_mode << 4)
+
+struct axp20x_led {
+	struct led_classdev cdev;
+	enum led_brightness current_brightness;
+	u8 mode : 1;
+	u8 ctrl : 1;
+	u8 ctrl_inverted : 1;
+	struct axp20x_dev *axp20x;
+};
+
+static inline struct axp20x_led *to_axp20x_led(struct led_classdev *cdev)
+{
+	return container_of(cdev, struct axp20x_led, cdev);
+}
+
+static int axp20x_led_setup(struct axp20x_led *priv)
+{
+	int ret;
+	u8 val;
+
+	/* Invert the logic, if necessary */
+	val = priv->ctrl ^ priv->ctrl_inverted;
+
+	ret = regmap_update_bits(priv->axp20x->regmap, AXP20X_CHGLED_CTRL_REG,
+				 AXP20X_CHGLED_CTRL_MASK,
+				 AXP20X_CHGLED_CTRL(val));
+	if (ret < 0)
+		return ret;
+
+	return regmap_update_bits(priv->axp20x->regmap, AXP20X_CHGLED_MODE_REG,
+				  AXP20X_CHGLED_MODE_MASK,
+				  AXP20X_CHGLED_MODE(priv->mode));
+}
+
+static ssize_t control_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	struct led_classdev *cdev = dev_get_drvdata(dev);
+	struct axp20x_led *priv = to_axp20x_led(cdev);
+
+	return sprintf(buf, "%d\n", priv->ctrl);
+}
+
+static ssize_t control_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t size)
+{
+	struct led_classdev *cdev = dev_get_drvdata(dev);
+	struct axp20x_led *priv = to_axp20x_led(cdev);
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	/**
+	 * Supported values are:
+	 *   - 0 : Manual control
+	 *   - 1 : Charger control
+	 */
+	if (val > 1)
+		return -EINVAL;
+
+	priv->ctrl = val;
+
+	return axp20x_led_setup(priv) ? : size;
+}
+static DEVICE_ATTR_RW(control);
+
+static ssize_t mode_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct led_classdev *cdev = dev_get_drvdata(dev);
+	struct axp20x_led *priv = to_axp20x_led(cdev);
+
+	return sprintf(buf, "%d\n", priv->mode);
+}
+
+static ssize_t mode_store(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t size)
+{
+	struct led_classdev *cdev = dev_get_drvdata(dev);
+	struct axp20x_led *priv = to_axp20x_led(cdev);
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 0, &val);
+	if (ret)
+		return ret;
+	/**
+	 * Supported values are:
+	 *   - 0 : Mode A
+	 *   - 1 : Mode B
+	 */
+	if (val > 1)
+		return -EINVAL;
+
+	priv->mode = val;
+
+	return axp20x_led_setup(priv) ? : size;
+}
+static DEVICE_ATTR_RW(mode);
+
+static struct attribute *axp20x_led_attrs[] = {
+	&dev_attr_control.attr,
+	&dev_attr_mode.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(axp20x_led);
+
+enum led_brightness axp20x_led_brightness_get(struct led_classdev *cdev)
+{
+	struct axp20x_led *priv = to_axp20x_led(cdev);
+	u32 val;
+	int ret;
+
+	ret = regmap_read(priv->axp20x->regmap, AXP20X_CHGLED_CTRL_REG, &val);
+	if (ret < 0)
+		return LED_OFF;
+
+	return (val & AXP20X_CHGLED_FUNC_FULL) ? LED_FULL : LED_OFF;
+}
+
+static int axp20x_led_brightness_set_blocking(struct led_classdev *cdev,
+					      enum led_brightness brightness)
+{
+	struct axp20x_led *priv = to_axp20x_led(cdev);
+	int ret = 0;
+
+	if (!priv->current_brightness && brightness)
+		ret = regmap_update_bits(priv->axp20x->regmap,
+					 AXP20X_CHGLED_CTRL_REG,
+					 AXP20X_CHGLED_FUNC_MASK,
+					 AXP20X_CHGLED_FUNC_FULL);
+	else if (priv->current_brightness && !brightness)
+		ret = regmap_update_bits(priv->axp20x->regmap,
+					 AXP20X_CHGLED_CTRL_REG,
+					 AXP20X_CHGLED_FUNC_MASK,
+					 AXP20X_CHGLED_FUNC_OFF);
+
+	if (ret < 0)
+		return ret;
+
+	priv->current_brightness = brightness;
+	return 0;
+}
+
+static int axp20x_led_parse_dt(struct axp20x_led *priv, struct device_node *np)
+{
+	const char *state;
+	int ret = 0;
+	u8 value;
+
+	priv->cdev.name = of_get_property(np, "label", NULL) ? : np->name;
+
+	if (!of_property_read_u8(np, "x-powers,charger-mode", &value)) {
+		priv->ctrl = AXP20X_CHGLED_CTRL_CHARGER;
+		priv->mode = (value < 2) ? value : 0;
+	} else {
+		priv->ctrl = AXP20X_CHGLED_CTRL_MANUAL;
+	}
+
+	priv->cdev.default_trigger = of_get_property(np,
+						     "linux,default-trigger",
+						     NULL);
+
+	state = of_get_property(np, "default-state", NULL);
+	if (state) {
+		if (!strcmp(state, "keep")) {
+			ret = axp20x_led_brightness_get(&priv->cdev);
+			if (ret < 0)
+				return ret;
+			priv->current_brightness = ret;
+		} else if (!strcmp(state, "on")) {
+			ret = axp20x_led_brightness_set_blocking(&priv->cdev,
+								 LED_FULL);
+		} else  {
+			ret = axp20x_led_brightness_set_blocking(&priv->cdev,
+								 LED_OFF);
+		}
+	}
+
+	return ret;
+}
+
+static const struct of_device_id axp20x_led_of_match[] = {
+	{ .compatible = "x-powers,axp20x-led" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, axp20x_led_of_match);
+
+static int axp20x_led_probe(struct platform_device *pdev)
+{
+	struct axp20x_led *priv;
+	int ret;
+
+	if (!of_device_is_available(pdev->dev.of_node))
+		return -ENODEV;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(struct axp20x_led),
+			    GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->axp20x = dev_get_drvdata(pdev->dev.parent);
+	if (!priv->axp20x) {
+		dev_err(&pdev->dev, "Failed to get parent data\n");
+		return -ENXIO;
+	}
+
+	priv->cdev.max_brightness = LED_FULL;
+	priv->cdev.brightness_set_blocking = axp20x_led_brightness_set_blocking;
+	priv->cdev.brightness_get = axp20x_led_brightness_get;
+	priv->cdev.groups = axp20x_led_groups;
+
+	ret = axp20x_led_parse_dt(priv, pdev->dev.of_node);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to set parameters\n");
+		return ret;
+	}
+
+	/**
+	 * For some reason in AXP209 the bit that controls CHGLED is with
+	 * inverted logic compared to all other PMICs.
+	 * If the PMIC is actually AXP209, set inverted flag and later use it
+	 * when configuring the LED.
+	 */
+	if (priv->axp20x->variant == AXP209_ID)
+		priv->ctrl_inverted = 1;
+
+	ret =  axp20x_led_setup(priv);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to configure led");
+		return ret;
+	}
+
+	return devm_led_classdev_register(&pdev->dev, &priv->cdev);
+}
+
+static struct platform_driver axp20x_led_driver = {
+	.driver = {
+		.name	= "axp20x-led",
+		.of_match_table = of_match_ptr(axp20x_led_of_match),
+	},
+	.probe = axp20x_led_probe,
+};
+
+module_platform_driver(axp20x_led_driver);
+
+MODULE_AUTHOR("Stefan Mavrodiev <stefan@...mex.com");
+MODULE_DESCRIPTION("X-Powers PMIC CHGLED driver");
+MODULE_LICENSE("GPL");
-- 
2.17.1

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