1 /*
2  * AS3711 PMIC backlight driver, using DCDC Step Up Converters
3  *
4  * Copyright (C) 2012 Renesas Electronics Corporation
5  * Author: Guennadi Liakhovetski, <g.liakhovetski@gmx.de>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the version 2 of the GNU General Public License as
9  * published by the Free Software Foundation
10  */
11 
12 #include <linux/backlight.h>
13 #include <linux/delay.h>
14 #include <linux/device.h>
15 #include <linux/err.h>
16 #include <linux/fb.h>
17 #include <linux/kernel.h>
18 #include <linux/mfd/as3711.h>
19 #include <linux/module.h>
20 #include <linux/platform_device.h>
21 #include <linux/regmap.h>
22 #include <linux/slab.h>
23 
24 enum as3711_bl_type {
25 	AS3711_BL_SU1,
26 	AS3711_BL_SU2,
27 };
28 
29 struct as3711_bl_data {
30 	bool powered;
31 	const char *fb_name;
32 	struct device *fb_dev;
33 	enum as3711_bl_type type;
34 	int brightness;
35 	struct backlight_device *bl;
36 };
37 
38 struct as3711_bl_supply {
39 	struct as3711_bl_data su1;
40 	struct as3711_bl_data su2;
41 	const struct as3711_bl_pdata *pdata;
42 	struct as3711 *as3711;
43 };
44 
45 static struct as3711_bl_supply *to_supply(struct as3711_bl_data *su)
46 {
47 	switch (su->type) {
48 	case AS3711_BL_SU1:
49 		return container_of(su, struct as3711_bl_supply, su1);
50 	case AS3711_BL_SU2:
51 		return container_of(su, struct as3711_bl_supply, su2);
52 	}
53 	return NULL;
54 }
55 
56 static int as3711_set_brightness_auto_i(struct as3711_bl_data *data,
57 					unsigned int brightness)
58 {
59 	struct as3711_bl_supply *supply = to_supply(data);
60 	struct as3711 *as3711 = supply->as3711;
61 	const struct as3711_bl_pdata *pdata = supply->pdata;
62 	int ret = 0;
63 
64 	/* Only all equal current values are supported */
65 	if (pdata->su2_auto_curr1)
66 		ret = regmap_write(as3711->regmap, AS3711_CURR1_VALUE,
67 				   brightness);
68 	if (!ret && pdata->su2_auto_curr2)
69 		ret = regmap_write(as3711->regmap, AS3711_CURR2_VALUE,
70 				   brightness);
71 	if (!ret && pdata->su2_auto_curr3)
72 		ret = regmap_write(as3711->regmap, AS3711_CURR3_VALUE,
73 				   brightness);
74 
75 	return ret;
76 }
77 
78 static int as3711_set_brightness_v(struct as3711 *as3711,
79 				   unsigned int brightness,
80 				   unsigned int reg)
81 {
82 	if (brightness > 31)
83 		return -EINVAL;
84 
85 	return regmap_update_bits(as3711->regmap, reg, 0xf0,
86 				  brightness << 4);
87 }
88 
89 static int as3711_bl_su2_reset(struct as3711_bl_supply *supply)
90 {
91 	struct as3711 *as3711 = supply->as3711;
92 	int ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_5,
93 				     3, supply->pdata->su2_fbprot);
94 	if (!ret)
95 		ret = regmap_update_bits(as3711->regmap,
96 					 AS3711_STEPUP_CONTROL_2, 1, 0);
97 	if (!ret)
98 		ret = regmap_update_bits(as3711->regmap,
99 					 AS3711_STEPUP_CONTROL_2, 1, 1);
100 	return ret;
101 }
102 
103 /*
104  * Someone with less fragile or less expensive hardware could try to simplify
105  * the brightness adjustment procedure.
106  */
107 static int as3711_bl_update_status(struct backlight_device *bl)
108 {
109 	struct as3711_bl_data *data = bl_get_data(bl);
110 	struct as3711_bl_supply *supply = to_supply(data);
111 	struct as3711 *as3711 = supply->as3711;
112 	int brightness = bl->props.brightness;
113 	int ret = 0;
114 
115 	dev_dbg(&bl->dev, "%s(): brightness %u, pwr %x, blank %x, state %x\n",
116 		__func__, bl->props.brightness, bl->props.power,
117 		bl->props.fb_blank, bl->props.state);
118 
119 	if (bl->props.power != FB_BLANK_UNBLANK ||
120 	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
121 	    bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
122 		brightness = 0;
123 
124 	if (data->type == AS3711_BL_SU1) {
125 		ret = as3711_set_brightness_v(as3711, brightness,
126 					      AS3711_STEPUP_CONTROL_1);
127 	} else {
128 		const struct as3711_bl_pdata *pdata = supply->pdata;
129 
130 		switch (pdata->su2_feedback) {
131 		case AS3711_SU2_VOLTAGE:
132 			ret = as3711_set_brightness_v(as3711, brightness,
133 						      AS3711_STEPUP_CONTROL_2);
134 			break;
135 		case AS3711_SU2_CURR_AUTO:
136 			ret = as3711_set_brightness_auto_i(data, brightness / 4);
137 			if (ret < 0)
138 				return ret;
139 			if (brightness) {
140 				ret = as3711_bl_su2_reset(supply);
141 				if (ret < 0)
142 					return ret;
143 				udelay(500);
144 				ret = as3711_set_brightness_auto_i(data, brightness);
145 			} else {
146 				ret = regmap_update_bits(as3711->regmap,
147 						AS3711_STEPUP_CONTROL_2, 1, 0);
148 			}
149 			break;
150 		/* Manual one current feedback pin below */
151 		case AS3711_SU2_CURR1:
152 			ret = regmap_write(as3711->regmap, AS3711_CURR1_VALUE,
153 					   brightness);
154 			break;
155 		case AS3711_SU2_CURR2:
156 			ret = regmap_write(as3711->regmap, AS3711_CURR2_VALUE,
157 					   brightness);
158 			break;
159 		case AS3711_SU2_CURR3:
160 			ret = regmap_write(as3711->regmap, AS3711_CURR3_VALUE,
161 					   brightness);
162 			break;
163 		default:
164 			ret = -EINVAL;
165 		}
166 	}
167 	if (!ret)
168 		data->brightness = brightness;
169 
170 	return ret;
171 }
172 
173 static int as3711_bl_get_brightness(struct backlight_device *bl)
174 {
175 	struct as3711_bl_data *data = bl_get_data(bl);
176 
177 	return data->brightness;
178 }
179 
180 static const struct backlight_ops as3711_bl_ops = {
181 	.update_status	= as3711_bl_update_status,
182 	.get_brightness	= as3711_bl_get_brightness,
183 };
184 
185 static int as3711_bl_init_su2(struct as3711_bl_supply *supply)
186 {
187 	struct as3711 *as3711 = supply->as3711;
188 	const struct as3711_bl_pdata *pdata = supply->pdata;
189 	u8 ctl = 0;
190 	int ret;
191 
192 	dev_dbg(as3711->dev, "%s(): use %u\n", __func__, pdata->su2_feedback);
193 
194 	/* Turn SU2 off */
195 	ret = regmap_write(as3711->regmap, AS3711_STEPUP_CONTROL_2, 0);
196 	if (ret < 0)
197 		return ret;
198 
199 	switch (pdata->su2_feedback) {
200 	case AS3711_SU2_VOLTAGE:
201 		ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 0);
202 		break;
203 	case AS3711_SU2_CURR1:
204 		ctl = 1;
205 		ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 1);
206 		break;
207 	case AS3711_SU2_CURR2:
208 		ctl = 4;
209 		ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 2);
210 		break;
211 	case AS3711_SU2_CURR3:
212 		ctl = 0x10;
213 		ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 3);
214 		break;
215 	case AS3711_SU2_CURR_AUTO:
216 		if (pdata->su2_auto_curr1)
217 			ctl = 2;
218 		if (pdata->su2_auto_curr2)
219 			ctl |= 8;
220 		if (pdata->su2_auto_curr3)
221 			ctl |= 0x20;
222 		ret = 0;
223 		break;
224 	default:
225 		return -EINVAL;
226 	}
227 
228 	if (!ret)
229 		ret = regmap_write(as3711->regmap, AS3711_CURR_CONTROL, ctl);
230 
231 	return ret;
232 }
233 
234 static int as3711_bl_register(struct platform_device *pdev,
235 			      unsigned int max_brightness, struct as3711_bl_data *su)
236 {
237 	struct backlight_properties props = {.type = BACKLIGHT_RAW,};
238 	struct backlight_device *bl;
239 
240 	/* max tuning I = 31uA for voltage- and 38250uA for current-feedback */
241 	props.max_brightness = max_brightness;
242 
243 	bl = devm_backlight_device_register(&pdev->dev,
244 				       su->type == AS3711_BL_SU1 ?
245 				       "as3711-su1" : "as3711-su2",
246 				       &pdev->dev, su,
247 				       &as3711_bl_ops, &props);
248 	if (IS_ERR(bl)) {
249 		dev_err(&pdev->dev, "failed to register backlight\n");
250 		return PTR_ERR(bl);
251 	}
252 
253 	bl->props.brightness = props.max_brightness;
254 
255 	backlight_update_status(bl);
256 
257 	su->bl = bl;
258 
259 	return 0;
260 }
261 
262 static int as3711_backlight_parse_dt(struct device *dev)
263 {
264 	struct as3711_bl_pdata *pdata = dev_get_platdata(dev);
265 	struct device_node *bl =
266 		of_find_node_by_name(dev->parent->of_node, "backlight"), *fb;
267 	int ret;
268 
269 	if (!bl) {
270 		dev_dbg(dev, "backlight node not found\n");
271 		return -ENODEV;
272 	}
273 
274 	fb = of_parse_phandle(bl, "su1-dev", 0);
275 	if (fb) {
276 		pdata->su1_fb = fb->full_name;
277 
278 		ret = of_property_read_u32(bl, "su1-max-uA", &pdata->su1_max_uA);
279 		if (pdata->su1_max_uA <= 0)
280 			ret = -EINVAL;
281 		if (ret < 0)
282 			return ret;
283 	}
284 
285 	fb = of_parse_phandle(bl, "su2-dev", 0);
286 	if (fb) {
287 		int count = 0;
288 
289 		pdata->su2_fb = fb->full_name;
290 
291 		ret = of_property_read_u32(bl, "su2-max-uA", &pdata->su2_max_uA);
292 		if (pdata->su2_max_uA <= 0)
293 			ret = -EINVAL;
294 		if (ret < 0)
295 			return ret;
296 
297 		if (of_find_property(bl, "su2-feedback-voltage", NULL)) {
298 			pdata->su2_feedback = AS3711_SU2_VOLTAGE;
299 			count++;
300 		}
301 		if (of_find_property(bl, "su2-feedback-curr1", NULL)) {
302 			pdata->su2_feedback = AS3711_SU2_CURR1;
303 			count++;
304 		}
305 		if (of_find_property(bl, "su2-feedback-curr2", NULL)) {
306 			pdata->su2_feedback = AS3711_SU2_CURR2;
307 			count++;
308 		}
309 		if (of_find_property(bl, "su2-feedback-curr3", NULL)) {
310 			pdata->su2_feedback = AS3711_SU2_CURR3;
311 			count++;
312 		}
313 		if (of_find_property(bl, "su2-feedback-curr-auto", NULL)) {
314 			pdata->su2_feedback = AS3711_SU2_CURR_AUTO;
315 			count++;
316 		}
317 		if (count != 1)
318 			return -EINVAL;
319 
320 		count = 0;
321 		if (of_find_property(bl, "su2-fbprot-lx-sd4", NULL)) {
322 			pdata->su2_fbprot = AS3711_SU2_LX_SD4;
323 			count++;
324 		}
325 		if (of_find_property(bl, "su2-fbprot-gpio2", NULL)) {
326 			pdata->su2_fbprot = AS3711_SU2_GPIO2;
327 			count++;
328 		}
329 		if (of_find_property(bl, "su2-fbprot-gpio3", NULL)) {
330 			pdata->su2_fbprot = AS3711_SU2_GPIO3;
331 			count++;
332 		}
333 		if (of_find_property(bl, "su2-fbprot-gpio4", NULL)) {
334 			pdata->su2_fbprot = AS3711_SU2_GPIO4;
335 			count++;
336 		}
337 		if (count != 1)
338 			return -EINVAL;
339 
340 		count = 0;
341 		if (of_find_property(bl, "su2-auto-curr1", NULL)) {
342 			pdata->su2_auto_curr1 = true;
343 			count++;
344 		}
345 		if (of_find_property(bl, "su2-auto-curr2", NULL)) {
346 			pdata->su2_auto_curr2 = true;
347 			count++;
348 		}
349 		if (of_find_property(bl, "su2-auto-curr3", NULL)) {
350 			pdata->su2_auto_curr3 = true;
351 			count++;
352 		}
353 
354 		/*
355 		 * At least one su2-auto-curr* must be specified iff
356 		 * AS3711_SU2_CURR_AUTO is used
357 		 */
358 		if (!count ^ (pdata->su2_feedback != AS3711_SU2_CURR_AUTO))
359 			return -EINVAL;
360 	}
361 
362 	return 0;
363 }
364 
365 static int as3711_backlight_probe(struct platform_device *pdev)
366 {
367 	struct as3711_bl_pdata *pdata = dev_get_platdata(&pdev->dev);
368 	struct as3711 *as3711 = dev_get_drvdata(pdev->dev.parent);
369 	struct as3711_bl_supply *supply;
370 	struct as3711_bl_data *su;
371 	unsigned int max_brightness;
372 	int ret;
373 
374 	if (!pdata) {
375 		dev_err(&pdev->dev, "No platform data, exiting...\n");
376 		return -ENODEV;
377 	}
378 
379 	if (pdev->dev.parent->of_node) {
380 		ret = as3711_backlight_parse_dt(&pdev->dev);
381 		if (ret < 0) {
382 			dev_err(&pdev->dev, "DT parsing failed: %d\n", ret);
383 			return ret;
384 		}
385 	}
386 
387 	if (!pdata->su1_fb && !pdata->su2_fb) {
388 		dev_err(&pdev->dev, "No framebuffer specified\n");
389 		return -EINVAL;
390 	}
391 
392 	/*
393 	 * Due to possible hardware damage I chose to block all modes,
394 	 * unsupported on my hardware. Anyone, wishing to use any of those modes
395 	 * will have to first review the code, then activate and test it.
396 	 */
397 	if (pdata->su1_fb ||
398 	    pdata->su2_fbprot != AS3711_SU2_GPIO4 ||
399 	    pdata->su2_feedback != AS3711_SU2_CURR_AUTO) {
400 		dev_warn(&pdev->dev,
401 			 "Attention! An untested mode has been chosen!\n"
402 			 "Please, review the code, enable, test, and report success:-)\n");
403 		return -EINVAL;
404 	}
405 
406 	supply = devm_kzalloc(&pdev->dev, sizeof(*supply), GFP_KERNEL);
407 	if (!supply)
408 		return -ENOMEM;
409 
410 	supply->as3711 = as3711;
411 	supply->pdata = pdata;
412 
413 	if (pdata->su1_fb) {
414 		su = &supply->su1;
415 		su->fb_name = pdata->su1_fb;
416 		su->type = AS3711_BL_SU1;
417 
418 		max_brightness = min(pdata->su1_max_uA, 31);
419 		ret = as3711_bl_register(pdev, max_brightness, su);
420 		if (ret < 0)
421 			return ret;
422 	}
423 
424 	if (pdata->su2_fb) {
425 		su = &supply->su2;
426 		su->fb_name = pdata->su2_fb;
427 		su->type = AS3711_BL_SU2;
428 
429 		switch (pdata->su2_fbprot) {
430 		case AS3711_SU2_GPIO2:
431 		case AS3711_SU2_GPIO3:
432 		case AS3711_SU2_GPIO4:
433 		case AS3711_SU2_LX_SD4:
434 			break;
435 		default:
436 			return -EINVAL;
437 		}
438 
439 		switch (pdata->su2_feedback) {
440 		case AS3711_SU2_VOLTAGE:
441 			max_brightness = min(pdata->su2_max_uA, 31);
442 			break;
443 		case AS3711_SU2_CURR1:
444 		case AS3711_SU2_CURR2:
445 		case AS3711_SU2_CURR3:
446 		case AS3711_SU2_CURR_AUTO:
447 			max_brightness = min(pdata->su2_max_uA / 150, 255);
448 			break;
449 		default:
450 			return -EINVAL;
451 		}
452 
453 		ret = as3711_bl_init_su2(supply);
454 		if (ret < 0)
455 			return ret;
456 
457 		ret = as3711_bl_register(pdev, max_brightness, su);
458 		if (ret < 0)
459 			return ret;
460 	}
461 
462 	platform_set_drvdata(pdev, supply);
463 
464 	return 0;
465 }
466 
467 static struct platform_driver as3711_backlight_driver = {
468 	.driver		= {
469 		.name	= "as3711-backlight",
470 	},
471 	.probe		= as3711_backlight_probe,
472 };
473 
474 module_platform_driver(as3711_backlight_driver);
475 
476 MODULE_DESCRIPTION("Backlight Driver for AS3711 PMICs");
477 MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de");
478 MODULE_LICENSE("GPL");
479 MODULE_ALIAS("platform:as3711-backlight");
480