| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * gpio_backlight.c - Simple GPIO-controlled backlight |
| */ |
| |
| #include <linux/backlight.h> |
| #include <linux/err.h> |
| #include <linux/fb.h> |
| #include <linux/gpio/consumer.h> |
| #include <linux/init.h> |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/of.h> |
| #include <linux/platform_data/gpio_backlight.h> |
| #include <linux/platform_device.h> |
| #include <linux/property.h> |
| #include <linux/slab.h> |
| |
| struct gpio_backlight { |
| struct device *dev; |
| struct gpio_desc *gpiod; |
| }; |
| |
| static int gpio_backlight_update_status(struct backlight_device *bl) |
| { |
| struct gpio_backlight *gbl = bl_get_data(bl); |
| |
| gpiod_set_value_cansleep(gbl->gpiod, backlight_get_brightness(bl)); |
| |
| return 0; |
| } |
| |
| static bool gpio_backlight_controls_device(struct backlight_device *bl, |
| struct device *display_dev) |
| { |
| struct gpio_backlight *gbl = bl_get_data(bl); |
| |
| return !gbl->dev || gbl->dev == display_dev; |
| } |
| |
| static const struct backlight_ops gpio_backlight_ops = { |
| .options = BL_CORE_SUSPENDRESUME, |
| .update_status = gpio_backlight_update_status, |
| .controls_device = gpio_backlight_controls_device, |
| }; |
| |
| static int gpio_backlight_probe(struct platform_device *pdev) |
| { |
| struct device *dev = &pdev->dev; |
| struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev); |
| struct device_node *of_node = dev->of_node; |
| struct backlight_properties props; |
| struct backlight_device *bl; |
| struct gpio_backlight *gbl; |
| int ret, init_brightness, def_value; |
| |
| gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL); |
| if (gbl == NULL) |
| return -ENOMEM; |
| |
| if (pdata) |
| gbl->dev = pdata->dev; |
| |
| def_value = device_property_read_bool(dev, "default-on"); |
| |
| gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS); |
| if (IS_ERR(gbl->gpiod)) |
| return dev_err_probe(dev, PTR_ERR(gbl->gpiod), |
| "The gpios parameter is missing or invalid\n"); |
| |
| memset(&props, 0, sizeof(props)); |
| props.type = BACKLIGHT_RAW; |
| props.max_brightness = 1; |
| bl = devm_backlight_device_register(dev, dev_name(dev), dev, gbl, |
| &gpio_backlight_ops, &props); |
| if (IS_ERR(bl)) { |
| dev_err(dev, "failed to register backlight\n"); |
| return PTR_ERR(bl); |
| } |
| |
| /* Set the initial power state */ |
| if (!of_node || !of_node->phandle) |
| /* Not booted with device tree or no phandle link to the node */ |
| bl->props.power = def_value ? FB_BLANK_UNBLANK |
| : FB_BLANK_POWERDOWN; |
| else if (gpiod_get_value_cansleep(gbl->gpiod) == 0) |
| bl->props.power = FB_BLANK_POWERDOWN; |
| else |
| bl->props.power = FB_BLANK_UNBLANK; |
| |
| bl->props.brightness = 1; |
| |
| init_brightness = backlight_get_brightness(bl); |
| ret = gpiod_direction_output(gbl->gpiod, init_brightness); |
| if (ret) { |
| dev_err(dev, "failed to set initial brightness\n"); |
| return ret; |
| } |
| |
| platform_set_drvdata(pdev, bl); |
| return 0; |
| } |
| |
| static struct of_device_id gpio_backlight_of_match[] = { |
| { .compatible = "gpio-backlight" }, |
| { /* sentinel */ } |
| }; |
| |
| MODULE_DEVICE_TABLE(of, gpio_backlight_of_match); |
| |
| static struct platform_driver gpio_backlight_driver = { |
| .driver = { |
| .name = "gpio-backlight", |
| .of_match_table = gpio_backlight_of_match, |
| }, |
| .probe = gpio_backlight_probe, |
| }; |
| |
| module_platform_driver(gpio_backlight_driver); |
| |
| MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>"); |
| MODULE_DESCRIPTION("GPIO-based Backlight Driver"); |
| MODULE_LICENSE("GPL"); |
| MODULE_ALIAS("platform:gpio-backlight"); |