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