diff options
Diffstat (limited to 'drivers/video/backlight/gpio_backlight.c')
| -rw-r--r-- | drivers/video/backlight/gpio_backlight.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c new file mode 100644 index 000000000..51c49f03e --- /dev/null +++ b/drivers/video/backlight/gpio_backlight.c @@ -0,0 +1,190 @@ +/* + * gpio_backlight.c - Simple GPIO-controlled backlight + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/backlight.h> +#include <linux/err.h> +#include <linux/fb.h> +#include <linux/gpio.h> /* Only for legacy support */ +#include <linux/gpio/consumer.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_gpio.h> +#include <linux/platform_data/gpio_backlight.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +struct gpio_backlight { + struct device *dev; + struct device *fbdev; + + struct gpio_desc *gpiod; + int def_value; +}; + +static int gpio_backlight_update_status(struct backlight_device *bl) +{ + struct gpio_backlight *gbl = bl_get_data(bl); + int brightness = bl->props.brightness; + + if (bl->props.power != FB_BLANK_UNBLANK || + bl->props.fb_blank != FB_BLANK_UNBLANK || + bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK)) + brightness = 0; + + gpiod_set_value_cansleep(gbl->gpiod, brightness); + + return 0; +} + +static int gpio_backlight_check_fb(struct backlight_device *bl, + struct fb_info *info) +{ + struct gpio_backlight *gbl = bl_get_data(bl); + + return gbl->fbdev == NULL || gbl->fbdev == info->dev; +} + +static const struct backlight_ops gpio_backlight_ops = { + .options = BL_CORE_SUSPENDRESUME, + .update_status = gpio_backlight_update_status, + .check_fb = gpio_backlight_check_fb, +}; + +static int gpio_backlight_probe_dt(struct platform_device *pdev, + struct gpio_backlight *gbl) +{ + struct device *dev = &pdev->dev; + struct device_node *np = dev->of_node; + int ret; + + gbl->def_value = of_property_read_bool(np, "default-on"); + + gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS); + if (IS_ERR(gbl->gpiod)) { + ret = PTR_ERR(gbl->gpiod); + + if (ret != -EPROBE_DEFER) { + dev_err(dev, + "Error: The gpios parameter is missing or invalid.\n"); + } + return ret; + } + + return 0; +} + +static int gpio_backlight_initial_power_state(struct gpio_backlight *gbl) +{ + struct device_node *node = gbl->dev->of_node; + + /* Not booted with device tree or no phandle link to the node */ + if (!node || !node->phandle) + return gbl->def_value ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN; + + /* if the enable GPIO is disabled, do not enable the backlight */ + if (gpiod_get_value_cansleep(gbl->gpiod) == 0) + return FB_BLANK_POWERDOWN; + + return FB_BLANK_UNBLANK; +} + + +static int gpio_backlight_probe(struct platform_device *pdev) +{ + struct gpio_backlight_platform_data *pdata = + dev_get_platdata(&pdev->dev); + struct backlight_properties props; + struct backlight_device *bl; + struct gpio_backlight *gbl; + struct device_node *np = pdev->dev.of_node; + int ret; + + if (!pdata && !np) { + dev_err(&pdev->dev, + "failed to find platform data or device tree node.\n"); + return -ENODEV; + } + + gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL); + if (gbl == NULL) + return -ENOMEM; + + gbl->dev = &pdev->dev; + + if (np) { + ret = gpio_backlight_probe_dt(pdev, gbl); + if (ret) + return ret; + } else { + /* + * Legacy platform data GPIO retrieveal. Do not expand + * the use of this code path, currently only used by one + * SH board. + */ + unsigned long flags = GPIOF_DIR_OUT; + + gbl->fbdev = pdata->fbdev; + gbl->def_value = pdata->def_value; + flags |= gbl->def_value ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW; + + ret = devm_gpio_request_one(gbl->dev, pdata->gpio, flags, + pdata ? pdata->name : "backlight"); + if (ret < 0) { + dev_err(&pdev->dev, "unable to request GPIO\n"); + return ret; + } + gbl->gpiod = gpio_to_desc(pdata->gpio); + if (!gbl->gpiod) + return -EINVAL; + } + + memset(&props, 0, sizeof(props)); + props.type = BACKLIGHT_RAW; + props.max_brightness = 1; + bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev), + &pdev->dev, gbl, &gpio_backlight_ops, + &props); + if (IS_ERR(bl)) { + dev_err(&pdev->dev, "failed to register backlight\n"); + return PTR_ERR(bl); + } + + bl->props.power = gpio_backlight_initial_power_state(gbl); + bl->props.brightness = 1; + + backlight_update_status(bl); + + platform_set_drvdata(pdev, bl); + return 0; +} + +#ifdef CONFIG_OF +static struct of_device_id gpio_backlight_of_match[] = { + { .compatible = "gpio-backlight" }, + { /* sentinel */ } +}; + +MODULE_DEVICE_TABLE(of, gpio_backlight_of_match); +#endif + +static struct platform_driver gpio_backlight_driver = { + .driver = { + .name = "gpio-backlight", + .of_match_table = of_match_ptr(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"); |