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 
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 
92 static int wm831x_backlight_update_status(struct backlight_device *bl)
93 {
94 	int brightness = bl->props.brightness;
95 
96 	if (bl->props.power != FB_BLANK_UNBLANK)
97 		brightness = 0;
98 
99 	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
100 		brightness = 0;
101 
102 	if (bl->props.state & BL_CORE_SUSPENDED)
103 		brightness = 0;
104 
105 	return wm831x_backlight_set(bl, brightness);
106 }
107 
108 static int wm831x_backlight_get_brightness(struct backlight_device *bl)
109 {
110 	struct wm831x_backlight_data *data = bl_get_data(bl);
111 
112 	return data->current_brightness;
113 }
114 
115 static const struct backlight_ops wm831x_backlight_ops = {
116 	.options = BL_CORE_SUSPENDRESUME,
117 	.update_status	= wm831x_backlight_update_status,
118 	.get_brightness	= wm831x_backlight_get_brightness,
119 };
120 
121 static int wm831x_backlight_probe(struct platform_device *pdev)
122 {
123 	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
124 	struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent);
125 	struct wm831x_backlight_pdata *pdata;
126 	struct wm831x_backlight_data *data;
127 	struct backlight_device *bl;
128 	struct backlight_properties props;
129 	int ret, i, max_isel, isink_reg, dcdc_cfg;
130 
131 	/* We need platform data */
132 	if (wm831x_pdata)
133 		pdata = wm831x_pdata->backlight;
134 	else
135 		pdata = NULL;
136 
137 	if (!pdata) {
138 		dev_err(&pdev->dev, "No platform data supplied\n");
139 		return -EINVAL;
140 	}
141 
142 	/* Figure out the maximum current we can use */
143 	for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) {
144 		if (wm831x_isinkv_values[i] > pdata->max_uA)
145 			break;
146 	}
147 
148 	if (i == 0) {
149 		dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA);
150 		return -EINVAL;
151 	}
152 	max_isel = i - 1;
153 
154 	if (pdata->max_uA != wm831x_isinkv_values[max_isel])
155 		dev_warn(&pdev->dev,
156 			 "Maximum current is %duA not %duA as requested\n",
157 			 wm831x_isinkv_values[max_isel], pdata->max_uA);
158 
159 	switch (pdata->isink) {
160 	case 1:
161 		isink_reg = WM831X_CURRENT_SINK_1;
162 		dcdc_cfg = 0;
163 		break;
164 	case 2:
165 		isink_reg = WM831X_CURRENT_SINK_2;
166 		dcdc_cfg = WM831X_DC4_FBSRC;
167 		break;
168 	default:
169 		dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink);
170 		return -EINVAL;
171 	}
172 
173 	/* Configure the ISINK to use for feedback */
174 	ret = wm831x_reg_unlock(wm831x);
175 	if (ret < 0)
176 		return ret;
177 
178 	ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC,
179 			      dcdc_cfg);
180 
181 	wm831x_reg_lock(wm831x);
182 	if (ret < 0)
183 		return ret;
184 
185 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
186 	if (data == NULL)
187 		return -ENOMEM;
188 
189 	data->wm831x = wm831x;
190 	data->current_brightness = 0;
191 	data->isink_reg = isink_reg;
192 
193 	memset(&props, 0, sizeof(props));
194 	props.type = BACKLIGHT_RAW;
195 	props.max_brightness = max_isel;
196 	bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev,
197 					data, &wm831x_backlight_ops, &props);
198 	if (IS_ERR(bl)) {
199 		dev_err(&pdev->dev, "failed to register backlight\n");
200 		return PTR_ERR(bl);
201 	}
202 
203 	bl->props.brightness = max_isel;
204 
205 	platform_set_drvdata(pdev, bl);
206 
207 	/* Disable the DCDC if it was started so we can bootstrap */
208 	wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0);
209 
210 	backlight_update_status(bl);
211 
212 	return 0;
213 }
214 
215 static struct platform_driver wm831x_backlight_driver = {
216 	.driver		= {
217 		.name	= "wm831x-backlight",
218 	},
219 	.probe		= wm831x_backlight_probe,
220 };
221 
222 module_platform_driver(wm831x_backlight_driver);
223 
224 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");
225 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");
226 MODULE_LICENSE("GPL");
227 MODULE_ALIAS("platform:wm831x-backlight");
228