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
24enum as3711_bl_type {
25	AS3711_BL_SU1,
26	AS3711_BL_SU2,
27};
28
29struct 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
38struct 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
45static 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
56static 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
78static 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
89static 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 */
107static 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
173static 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
180static const struct backlight_ops as3711_bl_ops = {
181	.update_status	= as3711_bl_update_status,
182	.get_brightness	= as3711_bl_get_brightness,
183};
184
185static 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
234static 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
262static 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
365static 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
467static struct platform_driver as3711_backlight_driver = {
468	.driver		= {
469		.name	= "as3711-backlight",
470	},
471	.probe		= as3711_backlight_probe,
472};
473
474module_platform_driver(as3711_backlight_driver);
475
476MODULE_DESCRIPTION("Backlight Driver for AS3711 PMICs");
477MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de");
478MODULE_LICENSE("GPL");
479MODULE_ALIAS("platform:as3711-backlight");
480