leds: lp8864: Add support for Texas Instruments LP8864, LP8864S, LP8866 LED-backlights

Add driver for TI LP8864, LP8864S, LP8866 4/6 channel LED-backlight drivers
with I2C interface.

Link: https://www.ti.com/lit/gpn/lp8864-q1
Link: https://www.ti.com/lit/gpn/lp8864s-q1
Link: https://www.ti.com/lit/gpn/lp8866-q1
Link: https://www.ti.com/lit/gpn/lp8866s-q1
Signed-off-by: Alexander Sverdlin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

MAINTAINERS

···
 F:	Documentation/devicetree/bindings/iio/dac/ti,dac7612.yaml
 F:	drivers/iio/dac/ti-dac7612.c
 
+TEXAS INSTRUMENTS' LB8864 LED BACKLIGHT DRIVER
+M:	Alexander Sverdlin <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	Documentation/devicetree/bindings/leds/backlight/ti,lp8864.yaml
+F:	drivers/leds/leds-lp8864.c
+
 TEXAS INSTRUMENTS' SYSTEM CONTROL INTERFACE (TISCI) PROTOCOL DRIVER
 M:	Nishanth Menon <[e-mail]>
 M:	Tero Kristo <[e-mail]>

drivers/leds/Kconfig

···
 	  on the LP8860 4 channel LED driver using the I2C communication
 	  bus.
 
+config LEDS_LP8864
+	tristate "LED support for the TI LP8864/LP8866 4/6 channel LED drivers"
+	depends on LEDS_CLASS && I2C && OF
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the TI LP8864-Q1,
+	  LP8864S-Q1, LP8866-Q1, LP8866S-Q1 4/6 channel LED backlight
+	  drivers with I2C interface.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called leds-lp8864.
+
 config LEDS_CLEVO_MAIL
 	tristate "Mail LED on Clevo notebook"
 	depends on LEDS_CLASS && BROKEN

drivers/leds/Makefile

···
 obj-$(CONFIG_LEDS_LP8501)		+= leds-lp8501.o
 obj-$(CONFIG_LEDS_LP8788)		+= leds-lp8788.o
 obj-$(CONFIG_LEDS_LP8860)		+= leds-lp8860.o
+obj-$(CONFIG_LEDS_LP8864)		+= leds-lp8864.o
 obj-$(CONFIG_LEDS_LT3593)		+= leds-lt3593.o
 obj-$(CONFIG_LEDS_MAX5970)		+= leds-max5970.o
 obj-$(CONFIG_LEDS_MAX77650)		+= leds-max77650.o

drivers/leds/leds-lp8864.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TI LP8864/LP8866 4/6 Channel LED Driver
+ *
+ * Copyright (C) 2024 Siemens AG
+ *
+ * Based on LP8860 driver by Dan Murphy <[e-mail]>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#define LP8864_BRT_CONTROL		0x00
+#define LP8864_USER_CONFIG1		0x04
+#define   LP8864_BRT_MODE_MASK		GENMASK(9, 8)
+#define   LP8864_BRT_MODE_REG		BIT(9)		/* Brightness control by DISPLAY_BRT reg */
+#define LP8864_SUPPLY_STATUS		0x0e
+#define LP8864_BOOST_STATUS		0x10
+#define LP8864_LED_STATUS		0x12
+#define   LP8864_LED_STATUS_WR_MASK	GENMASK(14, 9)	/* Writeable bits in the LED_STATUS reg */
+
+/* Textual meaning for status bits, starting from bit 1 */
+static const char *const lp8864_supply_status_msg[] = {
+	"Vin under-voltage fault",
+	"Vin over-voltage fault",
+	"Vdd under-voltage fault",
+	"Vin over-current fault",
+	"Missing charge pump fault",
+	"Charge pump fault",
+	"Missing boost sync fault",
+	"CRC error fault ",
+};
+
+/* Textual meaning for status bits, starting from bit 1 */
+static const char *const lp8864_boost_status_msg[] = {
+	"Boost OVP low fault",
+	"Boost OVP high fault",
+	"Boost over-current fault",
+	"Missing boost FSET resistor fault",
+	"Missing MODE SEL resistor fault",
+	"Missing LED resistor fault",
+	"ISET resistor short to ground fault",
+	"Thermal shutdown fault",
+};
+
+/* Textual meaning for every register bit */
+static const char *const lp8864_led_status_msg[] = {
+	"LED 1 fault",
+	"LED 2 fault",
+	"LED 3 fault",
+	"LED 4 fault",
+	"LED 5 fault",
+	"LED 6 fault",
+	"LED open fault",
+	"LED internal short fault",
+	"LED short to GND fault",
+	NULL, NULL, NULL,
+	"Invalid string configuration fault",
+	NULL,
+	"I2C time out fault",
+};
+
+/**
+ * struct lp8864_led
+ * @client: Pointer to the I2C client
+ * @led_dev: led class device pointer
+ * @regmap: Devices register map
+ * @led_status_mask: Helps to report LED fault only once
+ */
+struct lp8864_led {
+	struct i2c_client *client;
+	struct led_classdev led_dev;
+	struct regmap *regmap;
+	u16 led_status_mask;
+};
+
+static int lp8864_fault_check(struct lp8864_led *led)
+{
+	int ret, i;
+	unsigned int val;
+
+	ret = regmap_read(led->regmap, LP8864_SUPPLY_STATUS, &val);
+	if (ret)
+		goto err;
+
+	/* Odd bits are status bits, even bits are clear bits */
+	for (i = 0; i < ARRAY_SIZE(lp8864_supply_status_msg); i++)
+		if (val & BIT(i * 2 + 1))
+			dev_warn(&led->client->dev, "%s\n", lp8864_supply_status_msg[i]);
+
+	/*
+	 * Clear bits have an index preceding the corresponding Status bits;
+	 * both have to be written "1" simultaneously to clear the corresponding
+	 * Status bit.
+	 */
+	if (val)
+		ret = regmap_write(led->regmap, LP8864_SUPPLY_STATUS, val >> 1 | val);
+	if (ret)
+		goto err;
+
+	ret = regmap_read(led->regmap, LP8864_BOOST_STATUS, &val);
+	if (ret)
+		goto err;
+
+	/* Odd bits are status bits, even bits are clear bits */
+	for (i = 0; i < ARRAY_SIZE(lp8864_boost_status_msg); i++)
+		if (val & BIT(i * 2 + 1))
+			dev_warn(&led->client->dev, "%s\n", lp8864_boost_status_msg[i]);
+
+	if (val)
+		ret = regmap_write(led->regmap, LP8864_BOOST_STATUS, val >> 1 | val);
+	if (ret)
+		goto err;
+
+	ret = regmap_read(led->regmap, LP8864_LED_STATUS, &val);
+	if (ret)
+		goto err;
+
+	/*
+	 * Clear already reported faults that maintain their value until device
+	 * power-down
+	 */
+	val &= ~led->led_status_mask;
+
+	for (i = 0; i < ARRAY_SIZE(lp8864_led_status_msg); i++)
+		if (lp8864_led_status_msg[i] && val & BIT(i))
+			dev_warn(&led->client->dev, "%s\n", lp8864_led_status_msg[i]);
+
+	/*
+	 * Mark those which maintain their value until device power-down as
+	 * "already reported"
+	 */
+	led->led_status_mask |= val & ~LP8864_LED_STATUS_WR_MASK;
+
+	/*
+	 * Only bits 14, 12, 10 have to be cleared here, but others are RO,
+	 * we don't care what we write to them.
+	 */
+	if (val & LP8864_LED_STATUS_WR_MASK)
+		ret = regmap_write(led->regmap, LP8864_LED_STATUS, val >> 1 | val);
+	if (ret)
+		goto err;
+
+	return 0;
+
+err:
+	dev_err(&led->client->dev, "Failed to read/clear faults (%pe)\n", ERR_PTR(ret));
+
+	return ret;
+}
+
+static int lp8864_brightness_set(struct led_classdev *led_cdev,
+				 enum led_brightness brt_val)
+{
+	struct lp8864_led *led = container_of(led_cdev, struct lp8864_led, led_dev);
+	/* Scale 0..LED_FULL into 16-bit HW brightness */
+	unsigned int val = brt_val * 0xffff / LED_FULL;
+	int ret;
+
+	ret = lp8864_fault_check(led);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(led->regmap, LP8864_BRT_CONTROL, val);
+	if (ret)
+		dev_err(&led->client->dev, "Failed to write brightness value\n");
+
+	return ret;
+}
+
+static enum led_brightness lp8864_brightness_get(struct led_classdev *led_cdev)
+{
+	struct lp8864_led *led = container_of(led_cdev, struct lp8864_led, led_dev);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(led->regmap, LP8864_BRT_CONTROL, &val);
+	if (ret) {
+		dev_err(&led->client->dev, "Failed to read brightness value\n");
+		return ret;
+	}
+
+	/* Scale 16-bit HW brightness into 0..LED_FULL */
+	return val * LED_FULL / 0xffff;
+}
+
+static const struct regmap_config lp8864_regmap_config = {
+	.reg_bits		= 8,
+	.val_bits		= 16,
+	.val_format_endian	= REGMAP_ENDIAN_LITTLE,
+};
+
+static void lp8864_disable_gpio(void *data)
+{
+	struct gpio_desc *gpio = data;
+
+	gpiod_set_value(gpio, 0);
+}
+
+static int lp8864_probe(struct i2c_client *client)
+{
+	int ret;
+	struct lp8864_led *led;
+	struct device_node *np = dev_of_node(&client->dev);
+	struct device_node *child_node;
+	struct led_init_data init_data = {};
+	struct gpio_desc *enable_gpio;
+
+	led = devm_kzalloc(&client->dev, sizeof(*led), GFP_KERNEL);
+	if (!led)
+		return -ENOMEM;
+
+	child_node = of_get_next_available_child(np, NULL);
+	if (!child_node) {
+		dev_err(&client->dev, "No LED function defined\n");
+		return -EINVAL;
+	}
+
+	ret = devm_regulator_get_enable_optional(&client->dev, "vled");
+	if (ret && ret != -ENODEV)
+		return dev_err_probe(&client->dev, ret, "Failed to enable vled regulator\n");
+
+	enable_gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_HIGH);
+	if (IS_ERR(enable_gpio))
+		return dev_err_probe(&client->dev, PTR_ERR(enable_gpio),
+				     "Failed to get enable GPIO\n");
+
+	ret = devm_add_action_or_reset(&client->dev, lp8864_disable_gpio, enable_gpio);
+	if (ret)
+		return ret;
+
+	led->client = client;
+	led->led_dev.brightness_set_blocking = lp8864_brightness_set;
+	led->led_dev.brightness_get = lp8864_brightness_get;
+
+	led->regmap = devm_regmap_init_i2c(client, &lp8864_regmap_config);
+	if (IS_ERR(led->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(led->regmap),
+				     "Failed to allocate regmap\n");
+
+	/* Control brightness by DISPLAY_BRT register */
+	ret = regmap_update_bits(led->regmap, LP8864_USER_CONFIG1, LP8864_BRT_MODE_MASK,
+								   LP8864_BRT_MODE_REG);
+	if (ret) {
+		dev_err(&led->client->dev, "Failed to set brightness control mode\n");
+		return ret;
+	}
+
+	ret = lp8864_fault_check(led);
+	if (ret)
+		return ret;
+
+	init_data.fwnode = of_fwnode_handle(child_node);
+	init_data.devicename = "lp8864";
+	init_data.default_label = ":display_cluster";
+
+	ret = devm_led_classdev_register_ext(&client->dev, &led->led_dev, &init_data);
+	if (ret)
+		dev_err(&client->dev, "Failed to register LED device (%pe)\n", ERR_PTR(ret));
+
+	return ret;
+}
+
+static const struct i2c_device_id lp8864_id[] = {
+	{ "lp8864" },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, lp8864_id);
+
+static const struct of_device_id of_lp8864_leds_match[] = {
+	{ .compatible = "ti,lp8864" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, of_lp8864_leds_match);
+
+static struct i2c_driver lp8864_driver = {
+	.driver = {
+		.name	= "lp8864",
+		.of_match_table = of_lp8864_leds_match,
+	},
+	.probe		= lp8864_probe,
+	.id_table	= lp8864_id,
+};
+module_i2c_driver(lp8864_driver);
+
+MODULE_DESCRIPTION("Texas Instruments LP8864/LP8866 LED driver");
+MODULE_AUTHOR("Alexander Sverdlin <[e-mail]>");
+MODULE_LICENSE("GPL");