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 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
wm831x_backlight_get_brightness(struct backlight_device * bl)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
wm831x_backlight_probe(struct platform_device * pdev)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
