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path: root/drivers/leds/leds-lt3593.c
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Diffstat (limited to 'drivers/leds/leds-lt3593.c')
-rw-r--r--drivers/leds/leds-lt3593.c128
1 files changed, 128 insertions, 0 deletions
diff --git a/drivers/leds/leds-lt3593.c b/drivers/leds/leds-lt3593.c
new file mode 100644
index 0000000000..d0160fde0f
--- /dev/null
+++ b/drivers/leds/leds-lt3593.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
+
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/slab.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/property.h>
+
+#define LED_LT3593_NAME "lt3593"
+
+struct lt3593_led_data {
+ struct led_classdev cdev;
+ struct gpio_desc *gpiod;
+};
+
+static int lt3593_led_set(struct led_classdev *led_cdev,
+ enum led_brightness value)
+{
+ struct lt3593_led_data *led_dat =
+ container_of(led_cdev, struct lt3593_led_data, cdev);
+ int pulses;
+
+ /*
+ * The LT3593 resets its internal current level register to the maximum
+ * level on the first falling edge on the control pin. Each following
+ * falling edge decreases the current level by 625uA. Up to 32 pulses
+ * can be sent, so the maximum power reduction is 20mA.
+ * After a timeout of 128us, the value is taken from the register and
+ * applied is to the output driver.
+ */
+
+ if (value == 0) {
+ gpiod_set_value_cansleep(led_dat->gpiod, 0);
+ return 0;
+ }
+
+ pulses = 32 - (value * 32) / 255;
+
+ if (pulses == 0) {
+ gpiod_set_value_cansleep(led_dat->gpiod, 0);
+ mdelay(1);
+ gpiod_set_value_cansleep(led_dat->gpiod, 1);
+ return 0;
+ }
+
+ gpiod_set_value_cansleep(led_dat->gpiod, 1);
+
+ while (pulses--) {
+ gpiod_set_value_cansleep(led_dat->gpiod, 0);
+ udelay(1);
+ gpiod_set_value_cansleep(led_dat->gpiod, 1);
+ udelay(1);
+ }
+
+ return 0;
+}
+
+static int lt3593_led_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct lt3593_led_data *led_data;
+ struct fwnode_handle *child;
+ int ret, state = LEDS_GPIO_DEFSTATE_OFF;
+ struct led_init_data init_data = {};
+ const char *tmp;
+
+ led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
+ if (!led_data)
+ return -ENOMEM;
+
+ if (device_get_child_node_count(dev) != 1) {
+ dev_err(dev, "Device must have exactly one LED sub-node.");
+ return -EINVAL;
+ }
+
+ led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
+ if (IS_ERR(led_data->gpiod))
+ return PTR_ERR(led_data->gpiod);
+
+ child = device_get_next_child_node(dev, NULL);
+
+ if (!fwnode_property_read_string(child, "default-state", &tmp)) {
+ if (!strcmp(tmp, "on"))
+ state = LEDS_GPIO_DEFSTATE_ON;
+ }
+
+ led_data->cdev.brightness_set_blocking = lt3593_led_set;
+ led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
+
+ init_data.fwnode = child;
+ init_data.devicename = LED_LT3593_NAME;
+ init_data.default_label = ":";
+
+ ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
+ fwnode_handle_put(child);
+ if (ret < 0)
+ return ret;
+
+ platform_set_drvdata(pdev, led_data);
+
+ return 0;
+}
+
+static const struct of_device_id of_lt3593_leds_match[] = {
+ { .compatible = "lltc,lt3593", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
+
+static struct platform_driver lt3593_led_driver = {
+ .probe = lt3593_led_probe,
+ .driver = {
+ .name = "leds-lt3593",
+ .of_match_table = of_lt3593_leds_match,
+ },
+};
+
+module_platform_driver(lt3593_led_driver);
+
+MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
+MODULE_DESCRIPTION("LED driver for LT3593 controllers");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:leds-lt3593");