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