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