1 // SPDX-License-Identifier: GPL-2.0-only
2
3 #include <dt-bindings/leds/rt4831-backlight.h>
4 #include <linux/backlight.h>
5 #include <linux/bitops.h>
6 #include <linux/kernel.h>
7 #include <linux/module.h>
8 #include <linux/platform_device.h>
9 #include <linux/property.h>
10 #include <linux/regmap.h>
11
12 #define RT4831_REG_BLCFG 0x02
13 #define RT4831_REG_BLDIML 0x04
14 #define RT4831_REG_ENABLE 0x08
15 #define RT4831_REG_BLOPT2 0x11
16
17 #define RT4831_BLMAX_BRIGHTNESS 2048
18
19 #define RT4831_BLOVP_MASK GENMASK(7, 5)
20 #define RT4831_BLOVP_SHIFT 5
21 #define RT4831_BLPWMEN_MASK BIT(0)
22 #define RT4831_BLEN_MASK BIT(4)
23 #define RT4831_BLCH_MASK GENMASK(3, 0)
24 #define RT4831_BLDIML_MASK GENMASK(2, 0)
25 #define RT4831_BLDIMH_MASK GENMASK(10, 3)
26 #define RT4831_BLDIMH_SHIFT 3
27 #define RT4831_BLOCP_MASK GENMASK(1, 0)
28
29 #define RT4831_BLOCP_MINUA 900000
30 #define RT4831_BLOCP_MAXUA 1800000
31 #define RT4831_BLOCP_STEPUA 300000
32
33 struct rt4831_priv {
34 struct device *dev;
35 struct regmap *regmap;
36 struct backlight_device *bl;
37 };
38
rt4831_bl_update_status(struct backlight_device * bl_dev)39 static int rt4831_bl_update_status(struct backlight_device *bl_dev)
40 {
41 struct rt4831_priv *priv = bl_get_data(bl_dev);
42 int brightness = backlight_get_brightness(bl_dev);
43 unsigned int enable = brightness ? RT4831_BLEN_MASK : 0;
44 u8 v[2];
45 int ret;
46
47 if (brightness) {
48 v[0] = (brightness - 1) & RT4831_BLDIML_MASK;
49 v[1] = ((brightness - 1) & RT4831_BLDIMH_MASK) >> RT4831_BLDIMH_SHIFT;
50
51 ret = regmap_raw_write(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
52 if (ret)
53 return ret;
54 }
55
56 return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLEN_MASK, enable);
57
58 }
59
rt4831_bl_get_brightness(struct backlight_device * bl_dev)60 static int rt4831_bl_get_brightness(struct backlight_device *bl_dev)
61 {
62 struct rt4831_priv *priv = bl_get_data(bl_dev);
63 unsigned int val;
64 u8 v[2];
65 int ret;
66
67 ret = regmap_read(priv->regmap, RT4831_REG_ENABLE, &val);
68 if (ret)
69 return ret;
70
71 if (!(val & RT4831_BLEN_MASK))
72 return 0;
73
74 ret = regmap_raw_read(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
75 if (ret)
76 return ret;
77
78 ret = (v[1] << RT4831_BLDIMH_SHIFT) + (v[0] & RT4831_BLDIML_MASK) + 1;
79
80 return ret;
81 }
82
83 static const struct backlight_ops rt4831_bl_ops = {
84 .options = BL_CORE_SUSPENDRESUME,
85 .update_status = rt4831_bl_update_status,
86 .get_brightness = rt4831_bl_get_brightness,
87 };
88
rt4831_parse_backlight_properties(struct rt4831_priv * priv,struct backlight_properties * bl_props)89 static int rt4831_parse_backlight_properties(struct rt4831_priv *priv,
90 struct backlight_properties *bl_props)
91 {
92 struct device *dev = priv->dev;
93 u8 propval;
94 u32 brightness, ocp_uA;
95 unsigned int val = 0;
96 int ret;
97
98 /* common properties */
99 ret = device_property_read_u32(dev, "max-brightness", &brightness);
100 if (ret)
101 brightness = RT4831_BLMAX_BRIGHTNESS;
102
103 bl_props->max_brightness = min_t(u32, brightness, RT4831_BLMAX_BRIGHTNESS);
104
105 ret = device_property_read_u32(dev, "default-brightness", &brightness);
106 if (ret)
107 brightness = bl_props->max_brightness;
108
109 bl_props->brightness = min_t(u32, brightness, bl_props->max_brightness);
110
111 /* vendor properties */
112 if (device_property_read_bool(dev, "richtek,pwm-enable"))
113 val = RT4831_BLPWMEN_MASK;
114
115 ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLPWMEN_MASK, val);
116 if (ret)
117 return ret;
118
119 ret = device_property_read_u8(dev, "richtek,bled-ovp-sel", &propval);
120 if (ret)
121 propval = RT4831_BLOVPLVL_21V;
122
123 propval = min_t(u8, propval, RT4831_BLOVPLVL_29V);
124 ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLOVP_MASK,
125 propval << RT4831_BLOVP_SHIFT);
126 if (ret)
127 return ret;
128
129 /*
130 * This OCP level is used to protect and limit the inductor current.
131 * If inductor peak current reach the level, low-side MOSFET will be
132 * turned off. Meanwhile, the output channel current may be limited.
133 * To match the configured channel current, the inductor chosen must
134 * be higher than the OCP level.
135 *
136 * Not like the OVP level, the default 21V can be used in the most
137 * application. But if the chosen OCP level is smaller than needed,
138 * it will also affect the backlight channel output current to be
139 * smaller than the register setting.
140 */
141 ret = device_property_read_u32(dev, "richtek,bled-ocp-microamp",
142 &ocp_uA);
143 if (!ret) {
144 ocp_uA = clamp_val(ocp_uA, RT4831_BLOCP_MINUA,
145 RT4831_BLOCP_MAXUA);
146 val = DIV_ROUND_UP(ocp_uA - RT4831_BLOCP_MINUA,
147 RT4831_BLOCP_STEPUA);
148 ret = regmap_update_bits(priv->regmap, RT4831_REG_BLOPT2,
149 RT4831_BLOCP_MASK, val);
150 if (ret)
151 return ret;
152 }
153
154 ret = device_property_read_u8(dev, "richtek,channel-use", &propval);
155 if (ret) {
156 dev_err(dev, "richtek,channel-use DT property missing\n");
157 return ret;
158 }
159
160 if (!(propval & RT4831_BLCH_MASK)) {
161 dev_err(dev, "No channel specified\n");
162 return -EINVAL;
163 }
164
165 return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLCH_MASK, propval);
166 }
167
rt4831_bl_probe(struct platform_device * pdev)168 static int rt4831_bl_probe(struct platform_device *pdev)
169 {
170 struct rt4831_priv *priv;
171 struct backlight_properties bl_props = { .type = BACKLIGHT_RAW,
172 .scale = BACKLIGHT_SCALE_LINEAR };
173 int ret;
174
175 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
176 if (!priv)
177 return -ENOMEM;
178
179 priv->dev = &pdev->dev;
180
181 priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);
182 if (!priv->regmap) {
183 dev_err(&pdev->dev, "Failed to init regmap\n");
184 return -ENODEV;
185 }
186
187 ret = rt4831_parse_backlight_properties(priv, &bl_props);
188 if (ret) {
189 dev_err(&pdev->dev, "Failed to parse backlight properties\n");
190 return ret;
191 }
192
193 priv->bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev, priv,
194 &rt4831_bl_ops, &bl_props);
195 if (IS_ERR(priv->bl)) {
196 dev_err(&pdev->dev, "Failed to register backlight\n");
197 return PTR_ERR(priv->bl);
198 }
199
200 backlight_update_status(priv->bl);
201 platform_set_drvdata(pdev, priv);
202
203 return 0;
204 }
205
rt4831_bl_remove(struct platform_device * pdev)206 static void rt4831_bl_remove(struct platform_device *pdev)
207 {
208 struct rt4831_priv *priv = platform_get_drvdata(pdev);
209 struct backlight_device *bl_dev = priv->bl;
210
211 bl_dev->props.brightness = 0;
212 backlight_update_status(priv->bl);
213 }
214
215 static const struct of_device_id __maybe_unused rt4831_bl_of_match[] = {
216 { .compatible = "richtek,rt4831-backlight", },
217 {}
218 };
219 MODULE_DEVICE_TABLE(of, rt4831_bl_of_match);
220
221 static struct platform_driver rt4831_bl_driver = {
222 .driver = {
223 .name = "rt4831-backlight",
224 .of_match_table = rt4831_bl_of_match,
225 },
226 .probe = rt4831_bl_probe,
227 .remove_new = rt4831_bl_remove,
228 };
229 module_platform_driver(rt4831_bl_driver);
230
231 MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
232 MODULE_LICENSE("GPL v2");
233