Laurent Pinchart | 8b770e3 | 2013-07-04 21:13:24 +0200 | [diff] [blame^] | 1 | /* |
| 2 | * gpio_backlight.c - Simple GPIO-controlled backlight |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/backlight.h> |
| 10 | #include <linux/err.h> |
| 11 | #include <linux/fb.h> |
| 12 | #include <linux/gpio.h> |
| 13 | #include <linux/init.h> |
| 14 | #include <linux/kernel.h> |
| 15 | #include <linux/module.h> |
| 16 | #include <linux/platform_data/gpio_backlight.h> |
| 17 | #include <linux/platform_device.h> |
| 18 | #include <linux/slab.h> |
| 19 | |
| 20 | struct gpio_backlight { |
| 21 | struct device *dev; |
| 22 | struct device *fbdev; |
| 23 | |
| 24 | int gpio; |
| 25 | int active; |
| 26 | }; |
| 27 | |
| 28 | static int gpio_backlight_update_status(struct backlight_device *bl) |
| 29 | { |
| 30 | struct gpio_backlight *gbl = bl_get_data(bl); |
| 31 | int brightness = bl->props.brightness; |
| 32 | |
| 33 | if (bl->props.power != FB_BLANK_UNBLANK || |
| 34 | bl->props.fb_blank != FB_BLANK_UNBLANK || |
| 35 | bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK)) |
| 36 | brightness = 0; |
| 37 | |
| 38 | gpio_set_value(gbl->gpio, brightness ? gbl->active : !gbl->active); |
| 39 | |
| 40 | return 0; |
| 41 | } |
| 42 | |
| 43 | static int gpio_backlight_get_brightness(struct backlight_device *bl) |
| 44 | { |
| 45 | return bl->props.brightness; |
| 46 | } |
| 47 | |
| 48 | static int gpio_backlight_check_fb(struct backlight_device *bl, |
| 49 | struct fb_info *info) |
| 50 | { |
| 51 | struct gpio_backlight *gbl = bl_get_data(bl); |
| 52 | |
| 53 | return gbl->fbdev == NULL || gbl->fbdev == info->dev; |
| 54 | } |
| 55 | |
| 56 | static const struct backlight_ops gpio_backlight_ops = { |
| 57 | .options = BL_CORE_SUSPENDRESUME, |
| 58 | .update_status = gpio_backlight_update_status, |
| 59 | .get_brightness = gpio_backlight_get_brightness, |
| 60 | .check_fb = gpio_backlight_check_fb, |
| 61 | }; |
| 62 | |
| 63 | static int gpio_backlight_probe(struct platform_device *pdev) |
| 64 | { |
| 65 | struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data; |
| 66 | struct backlight_properties props; |
| 67 | struct backlight_device *bl; |
| 68 | struct gpio_backlight *gbl; |
| 69 | int ret; |
| 70 | |
| 71 | if (!pdata) { |
| 72 | dev_err(&pdev->dev, "failed to find platform data\n"); |
| 73 | return -ENODEV; |
| 74 | } |
| 75 | |
| 76 | gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL); |
| 77 | if (gbl == NULL) |
| 78 | return -ENOMEM; |
| 79 | |
| 80 | gbl->dev = &pdev->dev; |
| 81 | gbl->fbdev = pdata->fbdev; |
| 82 | gbl->gpio = pdata->gpio; |
| 83 | gbl->active = pdata->active_low ? 0 : 1; |
| 84 | |
| 85 | ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT | |
| 86 | (gbl->active ? GPIOF_INIT_LOW |
| 87 | : GPIOF_INIT_HIGH), |
| 88 | pdata->name); |
| 89 | if (ret < 0) { |
| 90 | dev_err(&pdev->dev, "unable to request GPIO\n"); |
| 91 | return ret; |
| 92 | } |
| 93 | |
| 94 | memset(&props, 0, sizeof(props)); |
| 95 | props.type = BACKLIGHT_RAW; |
| 96 | props.max_brightness = 1; |
| 97 | bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl, |
| 98 | &gpio_backlight_ops, &props); |
| 99 | if (IS_ERR(bl)) { |
| 100 | dev_err(&pdev->dev, "failed to register backlight\n"); |
| 101 | return PTR_ERR(bl); |
| 102 | } |
| 103 | |
| 104 | bl->props.brightness = pdata->def_value; |
| 105 | backlight_update_status(bl); |
| 106 | |
| 107 | platform_set_drvdata(pdev, bl); |
| 108 | return 0; |
| 109 | } |
| 110 | |
| 111 | static int gpio_backlight_remove(struct platform_device *pdev) |
| 112 | { |
| 113 | struct backlight_device *bl = platform_get_drvdata(pdev); |
| 114 | |
| 115 | backlight_device_unregister(bl); |
| 116 | return 0; |
| 117 | } |
| 118 | |
| 119 | static struct platform_driver gpio_backlight_driver = { |
| 120 | .driver = { |
| 121 | .name = "gpio-backlight", |
| 122 | .owner = THIS_MODULE, |
| 123 | }, |
| 124 | .probe = gpio_backlight_probe, |
| 125 | .remove = gpio_backlight_remove, |
| 126 | }; |
| 127 | |
| 128 | module_platform_driver(gpio_backlight_driver); |
| 129 | |
| 130 | MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>"); |
| 131 | MODULE_DESCRIPTION("GPIO-based Backlight Driver"); |
| 132 | MODULE_LICENSE("GPL"); |
| 133 | MODULE_ALIAS("platform:gpio-backlight"); |