1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
4  *      PCF50633 backlight device driver
5  */
6 
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/slab.h>
10 #include <linux/platform_device.h>
11 
12 #include <linux/backlight.h>
13 #include <linux/fb.h>
14 
15 #include <linux/mfd/pcf50633/core.h>
16 #include <linux/mfd/pcf50633/backlight.h>
17 
18 struct pcf50633_bl {
19 	struct pcf50633 *pcf;
20 	struct backlight_device *bl;
21 
22 	unsigned int brightness;
23 	unsigned int brightness_limit;
24 };
25 
26 /*
27  * pcf50633_bl_set_brightness_limit
28  *
29  * Update the brightness limit for the pc50633 backlight. The actual brightness
30  * will not go above the limit. This is useful to limit power drain for example
31  * on low battery.
32  *
33  * @dev: Pointer to a pcf50633 device
34  * @limit: The brightness limit. Valid values are 0-63
35  */
pcf50633_bl_set_brightness_limit(struct pcf50633 * pcf,unsigned int limit)36 int pcf50633_bl_set_brightness_limit(struct pcf50633 *pcf, unsigned int limit)
37 {
38 	struct pcf50633_bl *pcf_bl = platform_get_drvdata(pcf->bl_pdev);
39 
40 	if (!pcf_bl)
41 		return -ENODEV;
42 
43 	pcf_bl->brightness_limit = limit & 0x3f;
44 	backlight_update_status(pcf_bl->bl);
45 
46 	return 0;
47 }
48 
pcf50633_bl_update_status(struct backlight_device * bl)49 static int pcf50633_bl_update_status(struct backlight_device *bl)
50 {
51 	struct pcf50633_bl *pcf_bl = bl_get_data(bl);
52 	unsigned int new_brightness;
53 
54 
55 	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK) ||
56 		bl->props.power != FB_BLANK_UNBLANK)
57 		new_brightness = 0;
58 	else if (bl->props.brightness < pcf_bl->brightness_limit)
59 		new_brightness = bl->props.brightness;
60 	else
61 		new_brightness = pcf_bl->brightness_limit;
62 
63 
64 	if (pcf_bl->brightness == new_brightness)
65 		return 0;
66 
67 	if (new_brightness) {
68 		pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDOUT,
69 					new_brightness);
70 		if (!pcf_bl->brightness)
71 			pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDENA, 1);
72 	} else {
73 		pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDENA, 0);
74 	}
75 
76 	pcf_bl->brightness = new_brightness;
77 
78 	return 0;
79 }
80 
pcf50633_bl_get_brightness(struct backlight_device * bl)81 static int pcf50633_bl_get_brightness(struct backlight_device *bl)
82 {
83 	struct pcf50633_bl *pcf_bl = bl_get_data(bl);
84 
85 	return pcf_bl->brightness;
86 }
87 
88 static const struct backlight_ops pcf50633_bl_ops = {
89 	.get_brightness = pcf50633_bl_get_brightness,
90 	.update_status	= pcf50633_bl_update_status,
91 	.options	= BL_CORE_SUSPENDRESUME,
92 };
93 
pcf50633_bl_probe(struct platform_device * pdev)94 static int pcf50633_bl_probe(struct platform_device *pdev)
95 {
96 	struct pcf50633_bl *pcf_bl;
97 	struct device *parent = pdev->dev.parent;
98 	struct pcf50633_platform_data *pcf50633_data = dev_get_platdata(parent);
99 	struct pcf50633_bl_platform_data *pdata = pcf50633_data->backlight_data;
100 	struct backlight_properties bl_props;
101 
102 	pcf_bl = devm_kzalloc(&pdev->dev, sizeof(*pcf_bl), GFP_KERNEL);
103 	if (!pcf_bl)
104 		return -ENOMEM;
105 
106 	memset(&bl_props, 0, sizeof(bl_props));
107 	bl_props.type = BACKLIGHT_RAW;
108 	bl_props.max_brightness = 0x3f;
109 	bl_props.power = FB_BLANK_UNBLANK;
110 
111 	if (pdata) {
112 		bl_props.brightness = pdata->default_brightness;
113 		pcf_bl->brightness_limit = pdata->default_brightness_limit;
114 	} else {
115 		bl_props.brightness = 0x3f;
116 		pcf_bl->brightness_limit = 0x3f;
117 	}
118 
119 	pcf_bl->pcf = dev_to_pcf50633(pdev->dev.parent);
120 
121 	pcf_bl->bl = devm_backlight_device_register(&pdev->dev, pdev->name,
122 						&pdev->dev, pcf_bl,
123 						&pcf50633_bl_ops, &bl_props);
124 
125 	if (IS_ERR(pcf_bl->bl))
126 		return PTR_ERR(pcf_bl->bl);
127 
128 	platform_set_drvdata(pdev, pcf_bl);
129 
130 	pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
131 
132 	/*
133 	 * Should be different from bl_props.brightness, so we do not exit
134 	 * update_status early the first time it's called
135 	 */
136 	pcf_bl->brightness = pcf_bl->bl->props.brightness + 1;
137 
138 	backlight_update_status(pcf_bl->bl);
139 
140 	return 0;
141 }
142 
143 static struct platform_driver pcf50633_bl_driver = {
144 	.probe =	pcf50633_bl_probe,
145 	.driver = {
146 		.name = "pcf50633-backlight",
147 	},
148 };
149 
150 module_platform_driver(pcf50633_bl_driver);
151 
152 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
153 MODULE_DESCRIPTION("PCF50633 backlight driver");
154 MODULE_LICENSE("GPL");
155 MODULE_ALIAS("platform:pcf50633-backlight");
156