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
58enum {
59	MT6370_VID_COMMON = 1,
60	MT6370_VID_6372,
61};
62
63struct 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
73static 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
98static 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
123static 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
129static 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
239static 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
275static 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
321static 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
330static 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};
335MODULE_DEVICE_TABLE(of, mt6370_bl_of_match);
336
337static 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_new = mt6370_bl_remove,
344};
345module_platform_driver(mt6370_bl_driver);
346
347MODULE_AUTHOR("ChiaEn Wu <chiaen_wu@richtek.com>");
348MODULE_DESCRIPTION("MediaTek MT6370 Backlight Driver");
349MODULE_LICENSE("GPL v2");
350