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