leds: lm36274: Introduce the TI LM36274 LED driver

Introduce the LM36274 LED driver.  This driver uses the ti-lmu
MFD driver to probe this LED driver.  The driver configures only the
LED registers and enables the outputs according to the config file.

The driver utilizes the TI LMU (Lighting Management Unit) LED common
framework to set the brightness bits.
Signed-off-by: Dan Murphy <dmurphy@ti.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

drivers/leds/Kconfig

@@ -800,6 +800,14 @@ config LEDS_LM3697
 	  Say Y to enable the LM3697 LED driver for TI LMU devices.
 	  This supports the LED device LM3697.
 
+config LEDS_LM36274
+	tristate "LED driver for LM36274"
+	depends on LEDS_TI_LMU_COMMON
+	depends on MFD_TI_LMU
+	help
+	  Say Y to enable the LM36274 LED driver for TI LMU devices.
+	  This supports the LED device LM36274.
+
 comment "LED Triggers"
 source "drivers/leds/trigger/Kconfig"
 

drivers/leds/Makefile

@@ -83,6 +83,7 @@ obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
 obj-$(CONFIG_LEDS_LM3601X)		+= leds-lm3601x.o
 obj-$(CONFIG_LEDS_TI_LMU_COMMON)	+= leds-ti-lmu-common.o
 obj-$(CONFIG_LEDS_LM3697)		+= leds-lm3697.o
+obj-$(CONFIG_LEDS_LM36274)		+= leds-lm36274.o
 
 # LED SPI Drivers
 obj-$(CONFIG_LEDS_CR0014114)		+= leds-cr0014114.o

drivers/leds/leds-lm36274.c

+// SPDX-License-Identifier: GPL-2.0
+// TI LM36274 LED chip family driver
+// Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/leds.h>
+#include <linux/leds-ti-lmu-common.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#include <linux/mfd/ti-lmu.h>
+#include <linux/mfd/ti-lmu-register.h>
+
+#include <uapi/linux/uleds.h>
+
+#define LM36274_MAX_STRINGS	4
+#define LM36274_BL_EN		BIT(4)
+
+/**
+ * struct lm36274
+ * @pdev: platform device
+ * @led_dev: led class device
+ * @lmu_data: Register and setting values for common code
+ * @regmap: Devices register map
+ * @dev: Pointer to the devices device struct
+ * @led_sources - The LED strings supported in this array
+ * @num_leds - Number of LED strings are supported in this array
+ */
+struct lm36274 {
+	struct platform_device *pdev;
+	struct led_classdev led_dev;
+	struct ti_lmu_bank lmu_data;
+	struct regmap *regmap;
+	struct device *dev;
+
+	u32 led_sources[LM36274_MAX_STRINGS];
+	int num_leds;
+};
+
+static int lm36274_brightness_set(struct led_classdev *led_cdev,
+				enum led_brightness brt_val)
+{
+	struct lm36274 *led = container_of(led_cdev, struct lm36274, led_dev);
+
+	return ti_lmu_common_set_brightness(&led->lmu_data, brt_val);
+}
+
+static int lm36274_init(struct lm36274 *lm36274_data)
+{
+	int enable_val = 0;
+	int i;
+
+	for (i = 0; i < lm36274_data->num_leds; i++)
+		enable_val |= (1 << lm36274_data->led_sources[i]);
+
+	if (!enable_val) {
+		dev_err(lm36274_data->dev, "No LEDs were enabled\n");
+		return -EINVAL;
+	}
+
+	enable_val |= LM36274_BL_EN;
+
+	return regmap_write(lm36274_data->regmap, LM36274_REG_BL_EN,
+			    enable_val);
+}
+
+static int lm36274_parse_dt(struct lm36274 *lm36274_data)
+{
+	struct fwnode_handle *child = NULL;
+	char label[LED_MAX_NAME_SIZE];
+	struct device *dev = &lm36274_data->pdev->dev;
+	const char *name;
+	int child_cnt;
+	int ret = -EINVAL;
+
+	/* There should only be 1 node */
+	child_cnt = device_get_child_node_count(dev);
+	if (child_cnt != 1)
+		return -EINVAL;
+
+	device_for_each_child_node(dev, child) {
+		ret = fwnode_property_read_string(child, "label", &name);
+		if (ret)
+			snprintf(label, sizeof(label),
+				"%s::", lm36274_data->pdev->name);
+		else
+			snprintf(label, sizeof(label),
+				 "%s:%s", lm36274_data->pdev->name, name);
+
+		lm36274_data->num_leds = fwnode_property_read_u32_array(child,
+							  "led-sources",
+							  NULL, 0);
+		if (lm36274_data->num_leds <= 0)
+			return -ENODEV;
+
+		ret = fwnode_property_read_u32_array(child, "led-sources",
+						     lm36274_data->led_sources,
+						     lm36274_data->num_leds);
+		if (ret) {
+			dev_err(dev, "led-sources property missing\n");
+			return ret;
+		}
+
+		fwnode_property_read_string(child, "linux,default-trigger",
+					&lm36274_data->led_dev.default_trigger);
+
+	}
+
+	lm36274_data->lmu_data.regmap = lm36274_data->regmap;
+	lm36274_data->lmu_data.max_brightness = MAX_BRIGHTNESS_11BIT;
+	lm36274_data->lmu_data.msb_brightness_reg = LM36274_REG_BRT_MSB;
+	lm36274_data->lmu_data.lsb_brightness_reg = LM36274_REG_BRT_LSB;
+
+	lm36274_data->led_dev.name = label;
+	lm36274_data->led_dev.max_brightness = MAX_BRIGHTNESS_11BIT;
+	lm36274_data->led_dev.brightness_set_blocking = lm36274_brightness_set;
+
+	return 0;
+}
+
+static int lm36274_probe(struct platform_device *pdev)
+{
+	struct ti_lmu *lmu = dev_get_drvdata(pdev->dev.parent);
+	struct lm36274 *lm36274_data;
+	int ret;
+
+	lm36274_data = devm_kzalloc(&pdev->dev, sizeof(*lm36274_data),
+				    GFP_KERNEL);
+	if (!lm36274_data)
+		return -ENOMEM;
+
+	lm36274_data->pdev = pdev;
+	lm36274_data->dev = lmu->dev;
+	lm36274_data->regmap = lmu->regmap;
+	dev_set_drvdata(&pdev->dev, lm36274_data);
+
+	ret = lm36274_parse_dt(lm36274_data);
+	if (ret) {
+		dev_err(lm36274_data->dev, "Failed to parse DT node\n");
+		return ret;
+	}
+
+	ret = lm36274_init(lm36274_data);
+	if (ret) {
+		dev_err(lm36274_data->dev, "Failed to init the device\n");
+		return ret;
+	}
+
+	return devm_led_classdev_register(lm36274_data->dev,
+					 &lm36274_data->led_dev);
+}
+
+static const struct of_device_id of_lm36274_leds_match[] = {
+	{ .compatible = "ti,lm36274-backlight", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_lm36274_leds_match);
+
+static struct platform_driver lm36274_driver = {
+	.probe  = lm36274_probe,
+	.driver = {
+		.name = "lm36274-leds",
+	},
+};
+module_platform_driver(lm36274_driver)
+
+MODULE_DESCRIPTION("Texas Instruments LM36274 LED driver");
+MODULE_AUTHOR("Dan Murphy <dmurphy@ti.com>");
+MODULE_LICENSE("GPL v2");