1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2022 Richtek Technology Corp.
4 *
5 * Author: ChiaEn Wu <chiaen_wu@richtek.com>
6 */
7
8 #include <linux/backlight.h>
9 #include <linux/bitfield.h>
10 #include <linux/bits.h>
11 #include <linux/gpio/consumer.h>
12 #include <linux/kernel.h>
13 #include <linux/minmax.h>
14 #include <linux/mod_devicetable.h>
15 #include <linux/module.h>
16 #include <linux/platform_device.h>
17 #include <linux/property.h>
18 #include <linux/regmap.h>
19
20 #define MT6370_REG_DEV_INFO 0x100
21 #define MT6370_REG_BL_EN 0x1A0
22 #define MT6370_REG_BL_BSTCTRL 0x1A1
23 #define MT6370_REG_BL_PWM 0x1A2
24 #define MT6370_REG_BL_DIM2 0x1A4
25
26 #define MT6370_VENID_MASK GENMASK(7, 4)
27 #define MT6370_BL_EXT_EN_MASK BIT(7)
28 #define MT6370_BL_EN_MASK BIT(6)
29 #define MT6370_BL_CODE_MASK BIT(0)
30 #define MT6370_BL_CH_MASK GENMASK(5, 2)
31 #define MT6370_BL_CH_SHIFT 2
32 #define MT6370_BL_DIM2_COMMON_MASK GENMASK(2, 0)
33 #define MT6370_BL_DIM2_COMMON_SHIFT 3
34 #define MT6370_BL_DIM2_6372_MASK GENMASK(5, 0)
35 #define MT6370_BL_DIM2_6372_SHIFT 6
36 #define MT6370_BL_PWM_EN_MASK BIT(7)
37 #define MT6370_BL_PWM_HYS_EN_MASK BIT(2)
38 #define MT6370_BL_PWM_HYS_SEL_MASK GENMASK(1, 0)
39 #define MT6370_BL_OVP_EN_MASK BIT(7)
40 #define MT6370_BL_OVP_SEL_MASK GENMASK(6, 5)
41 #define MT6370_BL_OVP_SEL_SHIFT 5
42 #define MT6370_BL_OC_EN_MASK BIT(3)
43 #define MT6370_BL_OC_SEL_MASK GENMASK(2, 1)
44 #define MT6370_BL_OC_SEL_SHIFT 1
45
46 #define MT6370_BL_PWM_HYS_TH_MIN_STEP 1
47 #define MT6370_BL_PWM_HYS_TH_MAX_STEP 64
48 #define MT6370_BL_OVP_MIN_UV 17000000
49 #define MT6370_BL_OVP_MAX_UV 29000000
50 #define MT6370_BL_OVP_STEP_UV 4000000
51 #define MT6370_BL_OCP_MIN_UA 900000
52 #define MT6370_BL_OCP_MAX_UA 1800000
53 #define MT6370_BL_OCP_STEP_UA 300000
54 #define MT6370_BL_MAX_COMMON_BRIGHTNESS 2048
55 #define MT6370_BL_MAX_6372_BRIGHTNESS 16384
56 #define MT6370_BL_MAX_CH 15
57
58 enum {
59 MT6370_VID_COMMON = 1,
60 MT6370_VID_6372,
61 };
62
63 struct mt6370_priv {
64 u8 dim2_mask;
65 u8 dim2_shift;
66 int def_max_brightness;
67 struct backlight_device *bl;
68 struct device *dev;
69 struct gpio_desc *enable_gpio;
70 struct regmap *regmap;
71 };
72
mt6370_bl_update_status(struct backlight_device * bl_dev)73 static int mt6370_bl_update_status(struct backlight_device *bl_dev)
74 {
75 struct mt6370_priv *priv = bl_get_data(bl_dev);
76 int brightness = backlight_get_brightness(bl_dev);
77 unsigned int enable_val;
78 u8 brightness_val[2];
79 int ret;
80
81 if (brightness) {
82 brightness_val[0] = (brightness - 1) & priv->dim2_mask;
83 brightness_val[1] = (brightness - 1) >> priv->dim2_shift;
84
85 ret = regmap_raw_write(priv->regmap, MT6370_REG_BL_DIM2,
86 brightness_val, sizeof(brightness_val));
87 if (ret)
88 return ret;
89 }
90
91 gpiod_set_value(priv->enable_gpio, !!brightness);
92
93 enable_val = brightness ? MT6370_BL_EN_MASK : 0;
94 return regmap_update_bits(priv->regmap, MT6370_REG_BL_EN,
95 MT6370_BL_EN_MASK, enable_val);
96 }
97
mt6370_bl_get_brightness(struct backlight_device * bl_dev)98 static int mt6370_bl_get_brightness(struct backlight_device *bl_dev)
99 {
100 struct mt6370_priv *priv = bl_get_data(bl_dev);
101 unsigned int enable;
102 u8 brightness_val[2];
103 int brightness, ret;
104
105 ret = regmap_read(priv->regmap, MT6370_REG_BL_EN, &enable);
106 if (ret)
107 return ret;
108
109 if (!(enable & MT6370_BL_EN_MASK))
110 return 0;
111
112 ret = regmap_raw_read(priv->regmap, MT6370_REG_BL_DIM2,
113 brightness_val, sizeof(brightness_val));
114 if (ret)
115 return ret;
116
117 brightness = brightness_val[1] << priv->dim2_shift;
118 brightness += brightness_val[0] & priv->dim2_mask;
119
120 return brightness + 1;
121 }
122
123 static const struct backlight_ops mt6370_bl_ops = {
124 .options = BL_CORE_SUSPENDRESUME,
125 .update_status = mt6370_bl_update_status,
126 .get_brightness = mt6370_bl_get_brightness,
127 };
128
mt6370_init_backlight_properties(struct mt6370_priv * priv,struct backlight_properties * props)129 static int mt6370_init_backlight_properties(struct mt6370_priv *priv,
130 struct backlight_properties *props)
131 {
132 struct device *dev = priv->dev;
133 u8 prop_val;
134 u32 brightness, ovp_uV, ocp_uA;
135 unsigned int mask, val;
136 int ret;
137
138 /* Vendor optional properties */
139 val = 0;
140 if (device_property_read_bool(dev, "mediatek,bled-pwm-enable"))
141 val |= MT6370_BL_PWM_EN_MASK;
142
143 if (device_property_read_bool(dev, "mediatek,bled-pwm-hys-enable"))
144 val |= MT6370_BL_PWM_HYS_EN_MASK;
145
146 ret = device_property_read_u8(dev,
147 "mediatek,bled-pwm-hys-input-th-steps",
148 &prop_val);
149 if (!ret) {
150 prop_val = clamp_val(prop_val,
151 MT6370_BL_PWM_HYS_TH_MIN_STEP,
152 MT6370_BL_PWM_HYS_TH_MAX_STEP);
153 prop_val = prop_val <= 1 ? 0 :
154 prop_val <= 4 ? 1 :
155 prop_val <= 16 ? 2 : 3;
156 val |= prop_val;
157 }
158
159 ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_PWM,
160 val, val);
161 if (ret)
162 return ret;
163
164 val = 0;
165 if (device_property_read_bool(dev, "mediatek,bled-ovp-shutdown"))
166 val |= MT6370_BL_OVP_EN_MASK;
167
168 ret = device_property_read_u32(dev, "mediatek,bled-ovp-microvolt",
169 &ovp_uV);
170 if (!ret) {
171 ovp_uV = clamp_val(ovp_uV, MT6370_BL_OVP_MIN_UV,
172 MT6370_BL_OVP_MAX_UV);
173 ovp_uV = DIV_ROUND_UP(ovp_uV - MT6370_BL_OVP_MIN_UV,
174 MT6370_BL_OVP_STEP_UV);
175 val |= ovp_uV << MT6370_BL_OVP_SEL_SHIFT;
176 }
177
178 if (device_property_read_bool(dev, "mediatek,bled-ocp-shutdown"))
179 val |= MT6370_BL_OC_EN_MASK;
180
181 ret = device_property_read_u32(dev, "mediatek,bled-ocp-microamp",
182 &ocp_uA);
183 if (!ret) {
184 ocp_uA = clamp_val(ocp_uA, MT6370_BL_OCP_MIN_UA,
185 MT6370_BL_OCP_MAX_UA);
186 ocp_uA = DIV_ROUND_UP(ocp_uA - MT6370_BL_OCP_MIN_UA,
187 MT6370_BL_OCP_STEP_UA);
188 val |= ocp_uA << MT6370_BL_OC_SEL_SHIFT;
189 }
190
191 ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_BSTCTRL,
192 val, val);
193 if (ret)
194 return ret;
195
196 /* Common properties */
197 ret = device_property_read_u32(dev, "max-brightness", &brightness);
198 if (ret)
199 brightness = priv->def_max_brightness;
200
201 props->max_brightness = min_t(u32, brightness, priv->def_max_brightness);
202
203 ret = device_property_read_u32(dev, "default-brightness", &brightness);
204 if (ret)
205 brightness = props->max_brightness;
206
207 props->brightness = min_t(u32, brightness, props->max_brightness);
208
209 val = 0;
210 if (device_property_read_bool(dev, "mediatek,bled-exponential-mode-enable")) {
211 val |= MT6370_BL_CODE_MASK;
212 props->scale = BACKLIGHT_SCALE_NON_LINEAR;
213 } else
214 props->scale = BACKLIGHT_SCALE_LINEAR;
215
216 ret = device_property_read_u8(dev, "mediatek,bled-channel-use",
217 &prop_val);
218 if (ret) {
219 dev_err(dev, "mediatek,bled-channel-use DT property missing\n");
220 return ret;
221 }
222
223 if (!prop_val || prop_val > MT6370_BL_MAX_CH) {
224 dev_err(dev,
225 "No channel specified or over than upper bound (%d)\n",
226 prop_val);
227 return -EINVAL;
228 }
229
230 mask = MT6370_BL_EXT_EN_MASK | MT6370_BL_CH_MASK;
231 val |= prop_val << MT6370_BL_CH_SHIFT;
232
233 if (priv->enable_gpio)
234 val |= MT6370_BL_EXT_EN_MASK;
235
236 return regmap_update_bits(priv->regmap, MT6370_REG_BL_EN, mask, val);
237 }
238
mt6370_check_vendor_info(struct mt6370_priv * priv)239 static int mt6370_check_vendor_info(struct mt6370_priv *priv)
240 {
241 /*
242 * Because MT6372 uses 14 bits to control the brightness,
243 * MT6370 and MT6371 use 11 bits. This function is used
244 * to check the vendor's ID and set the relative hardware
245 * mask, shift and default maximum brightness value that
246 * should be used.
247 */
248 unsigned int dev_info, hw_vid, of_vid;
249 int ret;
250
251 ret = regmap_read(priv->regmap, MT6370_REG_DEV_INFO, &dev_info);
252 if (ret)
253 return ret;
254
255 of_vid = (uintptr_t)device_get_match_data(priv->dev);
256 hw_vid = FIELD_GET(MT6370_VENID_MASK, dev_info);
257 hw_vid = (hw_vid == 0x9 || hw_vid == 0xb) ? MT6370_VID_6372 : MT6370_VID_COMMON;
258 if (hw_vid != of_vid)
259 return dev_err_probe(priv->dev, -EINVAL,
260 "Buggy DT, wrong compatible string\n");
261
262 if (hw_vid == MT6370_VID_6372) {
263 priv->dim2_mask = MT6370_BL_DIM2_6372_MASK;
264 priv->dim2_shift = MT6370_BL_DIM2_6372_SHIFT;
265 priv->def_max_brightness = MT6370_BL_MAX_6372_BRIGHTNESS;
266 } else {
267 priv->dim2_mask = MT6370_BL_DIM2_COMMON_MASK;
268 priv->dim2_shift = MT6370_BL_DIM2_COMMON_SHIFT;
269 priv->def_max_brightness = MT6370_BL_MAX_COMMON_BRIGHTNESS;
270 }
271
272 return 0;
273 }
274
mt6370_bl_probe(struct platform_device * pdev)275 static int mt6370_bl_probe(struct platform_device *pdev)
276 {
277 struct backlight_properties props = {
278 .type = BACKLIGHT_RAW,
279 };
280 struct device *dev = &pdev->dev;
281 struct mt6370_priv *priv;
282 int ret;
283
284 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
285 if (!priv)
286 return -ENOMEM;
287
288 priv->dev = dev;
289
290 priv->regmap = dev_get_regmap(dev->parent, NULL);
291 if (!priv->regmap)
292 return dev_err_probe(dev, -ENODEV, "Failed to get regmap\n");
293
294 ret = mt6370_check_vendor_info(priv);
295 if (ret)
296 return dev_err_probe(dev, ret, "Failed to check vendor info\n");
297
298 priv->enable_gpio = devm_gpiod_get_optional(dev, "enable",
299 GPIOD_OUT_HIGH);
300 if (IS_ERR(priv->enable_gpio))
301 return dev_err_probe(dev, PTR_ERR(priv->enable_gpio),
302 "Failed to get 'enable' gpio\n");
303
304 ret = mt6370_init_backlight_properties(priv, &props);
305 if (ret)
306 return dev_err_probe(dev, ret,
307 "Failed to init backlight properties\n");
308
309 priv->bl = devm_backlight_device_register(dev, pdev->name, dev, priv,
310 &mt6370_bl_ops, &props);
311 if (IS_ERR(priv->bl))
312 return dev_err_probe(dev, PTR_ERR(priv->bl),
313 "Failed to register backlight\n");
314
315 backlight_update_status(priv->bl);
316 platform_set_drvdata(pdev, priv);
317
318 return 0;
319 }
320
mt6370_bl_remove(struct platform_device * pdev)321 static void mt6370_bl_remove(struct platform_device *pdev)
322 {
323 struct mt6370_priv *priv = platform_get_drvdata(pdev);
324 struct backlight_device *bl_dev = priv->bl;
325
326 bl_dev->props.brightness = 0;
327 backlight_update_status(priv->bl);
328 }
329
330 static const struct of_device_id mt6370_bl_of_match[] = {
331 { .compatible = "mediatek,mt6370-backlight", .data = (void *)MT6370_VID_COMMON },
332 { .compatible = "mediatek,mt6372-backlight", .data = (void *)MT6370_VID_6372 },
333 {}
334 };
335 MODULE_DEVICE_TABLE(of, mt6370_bl_of_match);
336
337 static struct platform_driver mt6370_bl_driver = {
338 .driver = {
339 .name = "mt6370-backlight",
340 .of_match_table = mt6370_bl_of_match,
341 },
342 .probe = mt6370_bl_probe,
343 .remove = mt6370_bl_remove,
344 };
345 module_platform_driver(mt6370_bl_driver);
346
347 MODULE_AUTHOR("ChiaEn Wu <chiaen_wu@richtek.com>");
348 MODULE_DESCRIPTION("MediaTek MT6370 Backlight Driver");
349 MODULE_LICENSE("GPL v2");
350