1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Backlight driver for Wolfson Microelectronics WM831x PMICs
4  *
5  * Copyright 2009 Wolfson Microelectonics plc
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/init.h>
10 #include <linux/platform_device.h>
11 #include <linux/module.h>
12 #include <linux/fb.h>
13 #include <linux/backlight.h>
14 #include <linux/slab.h>
15 
16 #include <linux/mfd/wm831x/core.h>
17 #include <linux/mfd/wm831x/pdata.h>
18 #include <linux/mfd/wm831x/regulator.h>
19 
20 struct wm831x_backlight_data {
21 	struct wm831x *wm831x;
22 	int isink_reg;
23 	int current_brightness;
24 };
25 
wm831x_backlight_set(struct backlight_device * bl,int brightness)26 static int wm831x_backlight_set(struct backlight_device *bl, int brightness)
27 {
28 	struct wm831x_backlight_data *data = bl_get_data(bl);
29 	struct wm831x *wm831x = data->wm831x;
30 	int power_up = !data->current_brightness && brightness;
31 	int power_down = data->current_brightness && !brightness;
32 	int ret;
33 
34 	if (power_up) {
35 		/* Enable the ISINK */
36 		ret = wm831x_set_bits(wm831x, data->isink_reg,
37 				      WM831X_CS1_ENA, WM831X_CS1_ENA);
38 		if (ret < 0)
39 			goto err;
40 
41 		/* Enable the DC-DC */
42 		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
43 				      WM831X_DC4_ENA, WM831X_DC4_ENA);
44 		if (ret < 0)
45 			goto err;
46 	}
47 
48 	if (power_down) {
49 		/* DCDC first */
50 		ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE,
51 				      WM831X_DC4_ENA, 0);
52 		if (ret < 0)
53 			goto err;
54 
55 		/* ISINK */
56 		ret = wm831x_set_bits(wm831x, data->isink_reg,
57 				      WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0);
58 		if (ret < 0)
59 			goto err;
60 	}
61 
62 	/* Set the new brightness */
63 	ret = wm831x_set_bits(wm831x, data->isink_reg,
64 			      WM831X_CS1_ISEL_MASK, brightness);
65 	if (ret < 0)
66 		goto err;
67 
68 	if (power_up) {
69 		/* Drive current through the ISINK */
70 		ret = wm831x_set_bits(wm831x, data->isink_reg,
71 				      WM831X_CS1_DRIVE, WM831X_CS1_DRIVE);
72 		if (ret < 0)
73 			return ret;
74 	}
75 
76 	data->current_brightness = brightness;
77 
78 	return 0;
79 
80 err:
81 	/* If we were in the middle of a power transition always shut down
82 	 * for safety.
83 	 */
84 	if (power_up || power_down) {
85 		wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
86 		wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0);
87 	}
88 
89 	return ret;
90 }
91 
wm831x_backlight_update_status(struct backlight_device * bl)92 static int wm831x_backlight_update_status(struct backlight_device *bl)
93 {
94 	return wm831x_backlight_set(bl, backlight_get_brightness(bl));
95 }
96 
wm831x_backlight_get_brightness(struct backlight_device * bl)97 static int wm831x_backlight_get_brightness(struct backlight_device *bl)
98 {
99 	struct wm831x_backlight_data *data = bl_get_data(bl);
100 
101 	return data->current_brightness;
102 }
103 
104 static const struct backlight_ops wm831x_backlight_ops = {
105 	.options = BL_CORE_SUSPENDRESUME,
106 	.update_status	= wm831x_backlight_update_status,
107 	.get_brightness	= wm831x_backlight_get_brightness,
108 };
109 
wm831x_backlight_probe(struct platform_device * pdev)110 static int wm831x_backlight_probe(struct platform_device *pdev)
111 {
112 	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
113 	struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent);
114 	struct wm831x_backlight_pdata *pdata;
115 	struct wm831x_backlight_data *data;
116 	struct backlight_device *bl;
117 	struct backlight_properties props;
118 	int ret, i, max_isel, isink_reg, dcdc_cfg;
119 
120 	/* We need platform data */
121 	if (wm831x_pdata)
122 		pdata = wm831x_pdata->backlight;
123 	else
124 		pdata = NULL;
125 
126 	if (!pdata) {
127 		dev_err(&pdev->dev, "No platform data supplied\n");
128 		return -EINVAL;
129 	}
130 
131 	/* Figure out the maximum current we can use */
132 	for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
133 		if (wm831x_isinkv_values[i] > pdata->max_uA)
134 			break;
135 	}
136 
137 	if (i == 0) {
138 		dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
139 		return -EINVAL;
140 	}
141 	max_isel = i - 1;
142 
143 	if (pdata->max_uA != wm831x_isinkv_values[max_isel])
144 		dev_warn(&pdev->dev,
145 			 "Maximum current is %duA not %duA as requested\n",
146 			 wm831x_isinkv_values[max_isel], pdata->max_uA);
147 
148 	switch (pdata->isink) {
149 	case 1:
150 		isink_reg = WM831X_CURRENT_SINK_1;
151 		dcdc_cfg = 0;
152 		break;
153 	case 2:
154 		isink_reg = WM831X_CURRENT_SINK_2;
155 		dcdc_cfg = WM831X_DC4_FBSRC;
156 		break;
157 	default:
158 		dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
159 		return -EINVAL;
160 	}
161 
162 	/* Configure the ISINK to use for feedback */
163 	ret = wm831x_reg_unlock(wm831x);
164 	if (ret < 0)
165 		return ret;
166 
167 	ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
168 			      dcdc_cfg);
169 
170 	wm831x_reg_lock(wm831x);
171 	if (ret < 0)
172 		return ret;
173 
174 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
175 	if (data == NULL)
176 		return -ENOMEM;
177 
178 	data->wm831x = wm831x;
179 	data->current_brightness = 0;
180 	data->isink_reg = isink_reg;
181 
182 	memset(&props, 0, sizeof(props));
183 	props.type = BACKLIGHT_RAW;
184 	props.max_brightness = max_isel;
185 	bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
186 					data, &wm831x_backlight_ops, &props);
187 	if (IS_ERR(bl)) {
188 		dev_err(&pdev->dev, "failed to register backlight\n");
189 		return PTR_ERR(bl);
190 	}
191 
192 	bl->props.brightness = max_isel;
193 
194 	platform_set_drvdata(pdev, bl);
195 
196 	/* Disable the DCDC if it was started so we can bootstrap */
197 	wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
198 
199 	backlight_update_status(bl);
200 
201 	return 0;
202 }
203 
204 static struct platform_driver wm831x_backlight_driver = {
205 	.driver		= {
206 		.name	= "wm831x-backlight",
207 	},
208 	.probe		= wm831x_backlight_probe,
209 };
210 
211 module_platform_driver(wm831x_backlight_driver);
212 
213 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
214 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
215 MODULE_LICENSE("GPL");
216 MODULE_ALIAS("platform:wm831x-backlight");
217