1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * linux/drivers/video/backlight/aat2870_bl.c
4  *
5  * Copyright (c) 2011, NVIDIA Corporation.
6  * Author: Jin Park <jinyoungp@nvidia.com>
7  */
8 
9 #include <linux/module.h>
10 #include <linux/kernel.h>
11 #include <linux/init.h>
12 #include <linux/platform_device.h>
13 #include <linux/mutex.h>
14 #include <linux/delay.h>
15 #include <linux/fb.h>
16 #include <linux/backlight.h>
17 #include <linux/mfd/aat2870.h>
18 
19 struct aat2870_bl_driver_data {
20 	struct platform_device *pdev;
21 	struct backlight_device *bd;
22 
23 	int channels;
24 	int max_current;
25 	int brightness; /* current brightness */
26 };
27 
28 static inline int aat2870_brightness(struct aat2870_bl_driver_data *aat2870_bl,
29 				     int brightness)
30 {
31 	struct backlight_device *bd = aat2870_bl->bd;
32 	int val;
33 
34 	val = brightness * (aat2870_bl->max_current - 1);
35 	val /= bd->props.max_brightness;
36 
37 	return val;
38 }
39 
40 static inline int aat2870_bl_enable(struct aat2870_bl_driver_data *aat2870_bl)
41 {
42 	struct aat2870_data *aat2870
43 			= dev_get_drvdata(aat2870_bl->pdev->dev.parent);
44 
45 	return aat2870->write(aat2870, AAT2870_BL_CH_EN,
46 			      (u8)aat2870_bl->channels);
47 }
48 
49 static inline int aat2870_bl_disable(struct aat2870_bl_driver_data *aat2870_bl)
50 {
51 	struct aat2870_data *aat2870
52 			= dev_get_drvdata(aat2870_bl->pdev->dev.parent);
53 
54 	return aat2870->write(aat2870, AAT2870_BL_CH_EN, 0x0);
55 }
56 
57 static int aat2870_bl_update_status(struct backlight_device *bd)
58 {
59 	struct aat2870_bl_driver_data *aat2870_bl = bl_get_data(bd);
60 	struct aat2870_data *aat2870 =
61 			dev_get_drvdata(aat2870_bl->pdev->dev.parent);
62 	int brightness = backlight_get_brightness(bd);
63 	int ret;
64 
65 	if ((brightness < 0) || (bd->props.max_brightness < brightness)) {
66 		dev_err(&bd->dev, "invalid brightness, %d\n", brightness);
67 		return -EINVAL;
68 	}
69 
70 	dev_dbg(&bd->dev, "brightness=%d, power=%d, state=%d\n",
71 		 bd->props.brightness, bd->props.power, bd->props.state);
72 
73 	ret = aat2870->write(aat2870, AAT2870_BLM,
74 			     (u8)aat2870_brightness(aat2870_bl, brightness));
75 	if (ret < 0)
76 		return ret;
77 
78 	if (brightness == 0) {
79 		ret = aat2870_bl_disable(aat2870_bl);
80 		if (ret < 0)
81 			return ret;
82 	} else if (aat2870_bl->brightness == 0) {
83 		ret = aat2870_bl_enable(aat2870_bl);
84 		if (ret < 0)
85 			return ret;
86 	}
87 
88 	aat2870_bl->brightness = brightness;
89 
90 	return 0;
91 }
92 
93 static int aat2870_bl_check_fb(struct backlight_device *bd, struct fb_info *fi)
94 {
95 	return 1;
96 }
97 
98 static const struct backlight_ops aat2870_bl_ops = {
99 	.options = BL_CORE_SUSPENDRESUME,
100 	.update_status = aat2870_bl_update_status,
101 	.check_fb = aat2870_bl_check_fb,
102 };
103 
104 static int aat2870_bl_probe(struct platform_device *pdev)
105 {
106 	struct aat2870_bl_platform_data *pdata = dev_get_platdata(&pdev->dev);
107 	struct aat2870_bl_driver_data *aat2870_bl;
108 	struct backlight_device *bd;
109 	struct backlight_properties props;
110 	int ret = 0;
111 
112 	if (!pdata) {
113 		dev_err(&pdev->dev, "No platform data\n");
114 		ret = -ENXIO;
115 		goto out;
116 	}
117 
118 	if (pdev->id != AAT2870_ID_BL) {
119 		dev_err(&pdev->dev, "Invalid device ID, %d\n", pdev->id);
120 		ret = -EINVAL;
121 		goto out;
122 	}
123 
124 	aat2870_bl = devm_kzalloc(&pdev->dev,
125 				  sizeof(struct aat2870_bl_driver_data),
126 				  GFP_KERNEL);
127 	if (!aat2870_bl) {
128 		ret = -ENOMEM;
129 		goto out;
130 	}
131 
132 	memset(&props, 0, sizeof(struct backlight_properties));
133 
134 	props.type = BACKLIGHT_RAW;
135 	bd = devm_backlight_device_register(&pdev->dev, "aat2870-backlight",
136 					&pdev->dev, aat2870_bl, &aat2870_bl_ops,
137 					&props);
138 	if (IS_ERR(bd)) {
139 		dev_err(&pdev->dev,
140 			"Failed allocate memory for backlight device\n");
141 		ret = PTR_ERR(bd);
142 		goto out;
143 	}
144 
145 	aat2870_bl->pdev = pdev;
146 	platform_set_drvdata(pdev, aat2870_bl);
147 
148 	aat2870_bl->bd = bd;
149 
150 	if (pdata->channels > 0)
151 		aat2870_bl->channels = pdata->channels;
152 	else
153 		aat2870_bl->channels = AAT2870_BL_CH_ALL;
154 
155 	if (pdata->max_current > 0)
156 		aat2870_bl->max_current = pdata->max_current;
157 	else
158 		aat2870_bl->max_current = AAT2870_CURRENT_27_9;
159 
160 	if (pdata->max_brightness > 0)
161 		bd->props.max_brightness = pdata->max_brightness;
162 	else
163 		bd->props.max_brightness = 255;
164 
165 	aat2870_bl->brightness = 0;
166 	bd->props.power = FB_BLANK_UNBLANK;
167 	bd->props.brightness = bd->props.max_brightness;
168 
169 	ret = aat2870_bl_update_status(bd);
170 	if (ret < 0) {
171 		dev_err(&pdev->dev, "Failed to initialize\n");
172 		return ret;
173 	}
174 
175 	return 0;
176 
177 out:
178 	return ret;
179 }
180 
181 static void aat2870_bl_remove(struct platform_device *pdev)
182 {
183 	struct aat2870_bl_driver_data *aat2870_bl = platform_get_drvdata(pdev);
184 	struct backlight_device *bd = aat2870_bl->bd;
185 
186 	bd->props.power = FB_BLANK_POWERDOWN;
187 	bd->props.brightness = 0;
188 	backlight_update_status(bd);
189 }
190 
191 static struct platform_driver aat2870_bl_driver = {
192 	.driver = {
193 		.name	= "aat2870-backlight",
194 	},
195 	.probe		= aat2870_bl_probe,
196 	.remove_new	= aat2870_bl_remove,
197 };
198 
199 static int __init aat2870_bl_init(void)
200 {
201 	return platform_driver_register(&aat2870_bl_driver);
202 }
203 subsys_initcall(aat2870_bl_init);
204 
205 static void __exit aat2870_bl_exit(void)
206 {
207 	platform_driver_unregister(&aat2870_bl_driver);
208 }
209 module_exit(aat2870_bl_exit);
210 
211 MODULE_DESCRIPTION("AnalogicTech AAT2870 Backlight");
212 MODULE_LICENSE("GPL");
213 MODULE_AUTHOR("Jin Park <jinyoungp@nvidia.com>");
214