1 // SPDX-License-Identifier: GPL-2.0-only
3  * Backlight driver for the Kinetic KTD253
4  * Based on code and know-how from the Samsung GT-S7710
7 #include <linux/backlight.h>
11 #include <linux/gpio/consumer.h>
42 	u16 current_ratio = ktd253->ratio;  in ktd253_backlight_update_status()
45 	dev_dbg(ktd253->dev, "new brightness/ratio: %d/32\n", brightness);  in ktd253_backlight_update_status()
54 		gpiod_set_value_cansleep(ktd253->gpiod, 0);  in ktd253_backlight_update_status()
56 		 * We need to keep the GPIO low for at least this long  in ktd253_backlight_update_status()
60 		ktd253->ratio = 0;  in ktd253_backlight_update_status()
65 		gpiod_set_value_cansleep(ktd253->gpiod, 1);  in ktd253_backlight_update_status()
81 		 * These GPIO operations absolutely can NOT sleep so no  in ktd253_backlight_update_status()
82 		 * _cansleep suffixes, and no using GPIO expanders on  in ktd253_backlight_update_status()
85 		gpiod_set_value(ktd253->gpiod, 0);  in ktd253_backlight_update_status()
87 		gpiod_set_value(ktd253->gpiod, 1);  in ktd253_backlight_update_status()
93 			current_ratio--;  in ktd253_backlight_update_status()
96 	ktd253->ratio = current_ratio;  in ktd253_backlight_update_status()
98 	dev_dbg(ktd253->dev, "new ratio set to %d/32\n", target_ratio);  in ktd253_backlight_update_status()
110 	struct device *dev = &pdev->dev;  in ktd253_backlight_probe()
119 		return -ENOMEM;  in ktd253_backlight_probe()
120 	ktd253->dev = dev;  in ktd253_backlight_probe()
122 	ret = device_property_read_u32(dev, "max-brightness", &max_brightness);  in ktd253_backlight_probe()
131 	ret = device_property_read_u32(dev, "default-brightness", &brightness);  in ktd253_backlight_probe()
142 		ktd253->ratio = KTD253_MAX_RATIO;  in ktd253_backlight_probe()
144 		ktd253->ratio = 0;  in ktd253_backlight_probe()
146 	ktd253->gpiod = devm_gpiod_get(dev, "enable",  in ktd253_backlight_probe()
149 	if (IS_ERR(ktd253->gpiod)) {  in ktd253_backlight_probe()
150 		ret = PTR_ERR(ktd253->gpiod);  in ktd253_backlight_probe()
151 		if (ret != -EPROBE_DEFER)  in ktd253_backlight_probe()
152 			dev_err(dev, "gpio line missing or invalid.\n");  in ktd253_backlight_probe()
155 	gpiod_set_consumer_name(ktd253->gpiod, dev_name(dev));  in ktd253_backlight_probe()
160 		dev_err(dev, "failed to register backlight\n");  in ktd253_backlight_probe()
163 	bl->props.max_brightness = max_brightness;  in ktd253_backlight_probe()
164 	/* When we just enable the GPIO line we set max brightness */  in ktd253_backlight_probe()
166 		bl->props.brightness = brightness;  in ktd253_backlight_probe()
167 		bl->props.power = FB_BLANK_UNBLANK;  in ktd253_backlight_probe()
169 		bl->props.brightness = 0;  in ktd253_backlight_probe()
170 		bl->props.power = FB_BLANK_POWERDOWN;  in ktd253_backlight_probe()
173 	ktd253->bl = bl;  in ktd253_backlight_probe()
188 		.name = "ktd253-backlight",
196 MODULE_DESCRIPTION("Kinetic KTD253 Backlight Driver");
198 MODULE_ALIAS("platform:ktd253-backlight");