1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * sky81452-backlight.c	SKY81452 backlight driver
4  *
5  * Copyright 2014 Skyworks Solutions Inc.
6  * Author : Gyungoh Yoo <jack.yoo@skyworksinc.com>
7  */
8 
9 #include <linux/backlight.h>
10 #include <linux/err.h>
11 #include <linux/gpio/consumer.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/of.h>
16 #include <linux/platform_device.h>
17 #include <linux/regmap.h>
18 #include <linux/slab.h>
19 
20 /* registers */
21 #define SKY81452_REG0	0x00
22 #define SKY81452_REG1	0x01
23 #define SKY81452_REG2	0x02
24 #define SKY81452_REG4	0x04
25 #define SKY81452_REG5	0x05
26 
27 /* bit mask */
28 #define SKY81452_CS	0xFF
29 #define SKY81452_EN	0x3F
30 #define SKY81452_IGPW	0x20
31 #define SKY81452_PWMMD	0x10
32 #define SKY81452_PHASE	0x08
33 #define SKY81452_ILIM	0x04
34 #define SKY81452_VSHRT	0x03
35 #define SKY81452_OCP	0x80
36 #define SKY81452_OTMP	0x40
37 #define SKY81452_SHRT	0x3F
38 #define SKY81452_OPN	0x3F
39 
40 #define SKY81452_DEFAULT_NAME "lcd-backlight"
41 #define SKY81452_MAX_BRIGHTNESS	(SKY81452_CS + 1)
42 
43 /**
44  * struct sky81452_platform_data
45  * @name:	backlight driver name.
46  *		If it is not defined, default name is lcd-backlight.
47  * @gpiod_enable:GPIO descriptor which control EN pin
48  * @enable:	Enable mask for current sink channel 1, 2, 3, 4, 5 and 6.
49  * @ignore_pwm:	true if DPWMI should be ignored.
50  * @dpwm_mode:	true is DPWM dimming mode, otherwise Analog dimming mode.
51  * @phase_shift:true is phase shift mode.
52  * @short_detection_threshold:	It should be one of 4, 5, 6 and 7V.
53  * @boost_current_limit:	It should be one of 2300, 2750mA.
54  */
55 struct sky81452_bl_platform_data {
56 	const char *name;
57 	struct gpio_desc *gpiod_enable;
58 	unsigned int enable;
59 	bool ignore_pwm;
60 	bool dpwm_mode;
61 	bool phase_shift;
62 	unsigned int short_detection_threshold;
63 	unsigned int boost_current_limit;
64 };
65 
66 #define CTZ(b) __builtin_ctz(b)
67 
sky81452_bl_update_status(struct backlight_device * bd)68 static int sky81452_bl_update_status(struct backlight_device *bd)
69 {
70 	const struct sky81452_bl_platform_data *pdata =
71 			dev_get_platdata(bd->dev.parent);
72 	const unsigned int brightness = (unsigned int)bd->props.brightness;
73 	struct regmap *regmap = bl_get_data(bd);
74 	int ret;
75 
76 	if (brightness > 0) {
77 		ret = regmap_write(regmap, SKY81452_REG0, brightness - 1);
78 		if (ret < 0)
79 			return ret;
80 
81 		return regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN,
82 					pdata->enable << CTZ(SKY81452_EN));
83 	}
84 
85 	return regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN, 0);
86 }
87 
88 static const struct backlight_ops sky81452_bl_ops = {
89 	.update_status = sky81452_bl_update_status,
90 };
91 
sky81452_bl_store_enable(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)92 static ssize_t sky81452_bl_store_enable(struct device *dev,
93 		struct device_attribute *attr, const char *buf, size_t count)
94 {
95 	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
96 	unsigned long value;
97 	int ret;
98 
99 	ret = kstrtoul(buf, 16, &value);
100 	if (ret < 0)
101 		return ret;
102 
103 	ret = regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN,
104 					value << CTZ(SKY81452_EN));
105 	if (ret < 0)
106 		return ret;
107 
108 	return count;
109 }
110 
sky81452_bl_show_open_short(struct device * dev,struct device_attribute * attr,char * buf)111 static ssize_t sky81452_bl_show_open_short(struct device *dev,
112 		struct device_attribute *attr, char *buf)
113 {
114 	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
115 	unsigned int reg, value = 0;
116 	char tmp[3];
117 	int i, ret;
118 
119 	reg = !strcmp(attr->attr.name, "open") ? SKY81452_REG5 : SKY81452_REG4;
120 	ret = regmap_read(regmap, reg, &value);
121 	if (ret < 0)
122 		return ret;
123 
124 	if (value & SKY81452_SHRT) {
125 		*buf = 0;
126 		for (i = 0; i < 6; i++) {
127 			if (value & 0x01) {
128 				sprintf(tmp, "%d ", i + 1);
129 				strcat(buf, tmp);
130 			}
131 			value >>= 1;
132 		}
133 		strcat(buf, "\n");
134 	} else {
135 		strcpy(buf, "none\n");
136 	}
137 
138 	return strlen(buf);
139 }
140 
sky81452_bl_show_fault(struct device * dev,struct device_attribute * attr,char * buf)141 static ssize_t sky81452_bl_show_fault(struct device *dev,
142 		struct device_attribute *attr, char *buf)
143 {
144 	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
145 	unsigned int value = 0;
146 	int ret;
147 
148 	ret = regmap_read(regmap, SKY81452_REG4, &value);
149 	if (ret < 0)
150 		return ret;
151 
152 	*buf = 0;
153 
154 	if (value & SKY81452_OCP)
155 		strcat(buf, "over-current ");
156 
157 	if (value & SKY81452_OTMP)
158 		strcat(buf, "over-temperature");
159 
160 	strcat(buf, "\n");
161 	return strlen(buf);
162 }
163 
164 static DEVICE_ATTR(enable, S_IWGRP | S_IWUSR, NULL, sky81452_bl_store_enable);
165 static DEVICE_ATTR(open, S_IRUGO, sky81452_bl_show_open_short, NULL);
166 static DEVICE_ATTR(short, S_IRUGO, sky81452_bl_show_open_short, NULL);
167 static DEVICE_ATTR(fault, S_IRUGO, sky81452_bl_show_fault, NULL);
168 
169 static struct attribute *sky81452_bl_attribute[] = {
170 	&dev_attr_enable.attr,
171 	&dev_attr_open.attr,
172 	&dev_attr_short.attr,
173 	&dev_attr_fault.attr,
174 	NULL
175 };
176 
177 static const struct attribute_group sky81452_bl_attr_group = {
178 	.attrs = sky81452_bl_attribute,
179 };
180 
181 #ifdef CONFIG_OF
sky81452_bl_parse_dt(struct device * dev)182 static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
183 							struct device *dev)
184 {
185 	struct device_node *np = of_node_get(dev->of_node);
186 	struct sky81452_bl_platform_data *pdata;
187 	int num_entry;
188 	unsigned int sources[6];
189 	int ret;
190 
191 	if (!np) {
192 		dev_err(dev, "backlight node not found.\n");
193 		return ERR_PTR(-ENODATA);
194 	}
195 
196 	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
197 	if (!pdata) {
198 		of_node_put(np);
199 		return ERR_PTR(-ENOMEM);
200 	}
201 
202 	of_property_read_string(np, "name", &pdata->name);
203 	pdata->ignore_pwm = of_property_read_bool(np, "skyworks,ignore-pwm");
204 	pdata->dpwm_mode = of_property_read_bool(np, "skyworks,dpwm-mode");
205 	pdata->phase_shift = of_property_read_bool(np, "skyworks,phase-shift");
206 	pdata->gpiod_enable = devm_gpiod_get_optional(dev, NULL, GPIOD_OUT_HIGH);
207 
208 	ret = of_property_count_u32_elems(np, "led-sources");
209 	if (ret < 0) {
210 		pdata->enable = SKY81452_EN >> CTZ(SKY81452_EN);
211 	} else {
212 		num_entry = ret;
213 		if (num_entry > 6)
214 			num_entry = 6;
215 
216 		ret = of_property_read_u32_array(np, "led-sources", sources,
217 					num_entry);
218 		if (ret < 0) {
219 			dev_err(dev, "led-sources node is invalid.\n");
220 			of_node_put(np);
221 			return ERR_PTR(-EINVAL);
222 		}
223 
224 		pdata->enable = 0;
225 		while (--num_entry)
226 			pdata->enable |= (1 << sources[num_entry]);
227 	}
228 
229 	ret = of_property_read_u32(np,
230 			"skyworks,short-detection-threshold-volt",
231 			&pdata->short_detection_threshold);
232 	if (ret < 0)
233 		pdata->short_detection_threshold = 7;
234 
235 	ret = of_property_read_u32(np, "skyworks,current-limit-mA",
236 			&pdata->boost_current_limit);
237 	if (ret < 0)
238 		pdata->boost_current_limit = 2750;
239 
240 	of_node_put(np);
241 	return pdata;
242 }
243 #else
sky81452_bl_parse_dt(struct device * dev)244 static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
245 							struct device *dev)
246 {
247 	return ERR_PTR(-EINVAL);
248 }
249 #endif
250 
sky81452_bl_init_device(struct regmap * regmap,struct sky81452_bl_platform_data * pdata)251 static int sky81452_bl_init_device(struct regmap *regmap,
252 		struct sky81452_bl_platform_data *pdata)
253 {
254 	unsigned int value;
255 
256 	value = pdata->ignore_pwm ? SKY81452_IGPW : 0;
257 	value |= pdata->dpwm_mode ? SKY81452_PWMMD : 0;
258 	value |= pdata->phase_shift ? 0 : SKY81452_PHASE;
259 
260 	if (pdata->boost_current_limit == 2300)
261 		value |= SKY81452_ILIM;
262 	else if (pdata->boost_current_limit != 2750)
263 		return -EINVAL;
264 
265 	if (pdata->short_detection_threshold < 4 ||
266 				pdata->short_detection_threshold > 7)
267 		return -EINVAL;
268 	value |= (7 - pdata->short_detection_threshold) << CTZ(SKY81452_VSHRT);
269 
270 	return regmap_write(regmap, SKY81452_REG2, value);
271 }
272 
sky81452_bl_probe(struct platform_device * pdev)273 static int sky81452_bl_probe(struct platform_device *pdev)
274 {
275 	struct device *dev = &pdev->dev;
276 	struct regmap *regmap = dev_get_drvdata(dev->parent);
277 	struct sky81452_bl_platform_data *pdata;
278 	struct backlight_device *bd;
279 	struct backlight_properties props;
280 	const char *name;
281 	int ret;
282 
283 	pdata = sky81452_bl_parse_dt(dev);
284 	if (IS_ERR(pdata))
285 		return PTR_ERR(pdata);
286 
287 	ret = sky81452_bl_init_device(regmap, pdata);
288 	if (ret < 0) {
289 		dev_err(dev, "failed to initialize. err=%d\n", ret);
290 		return ret;
291 	}
292 
293 	memset(&props, 0, sizeof(props));
294 	props.max_brightness = SKY81452_MAX_BRIGHTNESS;
295 	name = pdata->name ? pdata->name : SKY81452_DEFAULT_NAME;
296 	bd = devm_backlight_device_register(dev, name, dev, regmap,
297 						&sky81452_bl_ops, &props);
298 	if (IS_ERR(bd)) {
299 		dev_err(dev, "failed to register. err=%ld\n", PTR_ERR(bd));
300 		return PTR_ERR(bd);
301 	}
302 
303 	platform_set_drvdata(pdev, bd);
304 
305 	ret = sysfs_create_group(&bd->dev.kobj, &sky81452_bl_attr_group);
306 	if (ret < 0) {
307 		dev_err(dev, "failed to create attribute. err=%d\n", ret);
308 		return ret;
309 	}
310 
311 	return ret;
312 }
313 
sky81452_bl_remove(struct platform_device * pdev)314 static int sky81452_bl_remove(struct platform_device *pdev)
315 {
316 	const struct sky81452_bl_platform_data *pdata =
317 						dev_get_platdata(&pdev->dev);
318 	struct backlight_device *bd = platform_get_drvdata(pdev);
319 
320 	sysfs_remove_group(&bd->dev.kobj, &sky81452_bl_attr_group);
321 
322 	bd->props.power = FB_BLANK_UNBLANK;
323 	bd->props.brightness = 0;
324 	backlight_update_status(bd);
325 
326 	if (pdata->gpiod_enable)
327 		gpiod_set_value_cansleep(pdata->gpiod_enable, 0);
328 
329 	return 0;
330 }
331 
332 #ifdef CONFIG_OF
333 static const struct of_device_id sky81452_bl_of_match[] = {
334 	{ .compatible = "skyworks,sky81452-backlight", },
335 	{ }
336 };
337 MODULE_DEVICE_TABLE(of, sky81452_bl_of_match);
338 #endif
339 
340 static struct platform_driver sky81452_bl_driver = {
341 	.driver = {
342 		.name = "sky81452-backlight",
343 		.of_match_table = of_match_ptr(sky81452_bl_of_match),
344 	},
345 	.probe = sky81452_bl_probe,
346 	.remove = sky81452_bl_remove,
347 };
348 
349 module_platform_driver(sky81452_bl_driver);
350 
351 MODULE_DESCRIPTION("Skyworks SKY81452 backlight driver");
352 MODULE_AUTHOR("Gyungoh Yoo <jack.yoo@skyworksinc.com>");
353 MODULE_LICENSE("GPL v2");
354