1/*
2 * sky81452-backlight.c	SKY81452 backlight driver
3 *
4 * Copyright 2014 Skyworks Solutions Inc.
5 * Author : Gyungoh Yoo <jack.yoo@skyworksinc.com>
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2
9 * as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License along
17 * with this program; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20#include <linux/backlight.h>
21#include <linux/err.h>
22#include <linux/gpio.h>
23#include <linux/init.h>
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/of.h>
27#include <linux/of_gpio.h>
28#include <linux/platform_device.h>
29#include <linux/regmap.h>
30#include <linux/platform_data/sky81452-backlight.h>
31#include <linux/slab.h>
32
33/* registers */
34#define SKY81452_REG0	0x00
35#define SKY81452_REG1	0x01
36#define SKY81452_REG2	0x02
37#define SKY81452_REG4	0x04
38#define SKY81452_REG5	0x05
39
40/* bit mask */
41#define SKY81452_CS	0xFF
42#define SKY81452_EN	0x3F
43#define SKY81452_IGPW	0x20
44#define SKY81452_PWMMD	0x10
45#define SKY81452_PHASE	0x08
46#define SKY81452_ILIM	0x04
47#define SKY81452_VSHRT	0x03
48#define SKY81452_OCP	0x80
49#define SKY81452_OTMP	0x40
50#define SKY81452_SHRT	0x3F
51#define SKY81452_OPN	0x3F
52
53#define SKY81452_DEFAULT_NAME "lcd-backlight"
54#define SKY81452_MAX_BRIGHTNESS	(SKY81452_CS + 1)
55
56#define CTZ(b) __builtin_ctz(b)
57
58static int sky81452_bl_update_status(struct backlight_device *bd)
59{
60	const struct sky81452_bl_platform_data *pdata =
61			dev_get_platdata(bd->dev.parent);
62	const unsigned int brightness = (unsigned int)bd->props.brightness;
63	struct regmap *regmap = bl_get_data(bd);
64	int ret;
65
66	if (brightness > 0) {
67		ret = regmap_write(regmap, SKY81452_REG0, brightness - 1);
68		if (IS_ERR_VALUE(ret))
69			return ret;
70
71		return regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN,
72					pdata->enable << CTZ(SKY81452_EN));
73	}
74
75	return regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN, 0);
76}
77
78static const struct backlight_ops sky81452_bl_ops = {
79	.update_status = sky81452_bl_update_status,
80};
81
82static ssize_t sky81452_bl_store_enable(struct device *dev,
83		struct device_attribute *attr, const char *buf, size_t count)
84{
85	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
86	unsigned long value;
87	int ret;
88
89	ret = kstrtoul(buf, 16, &value);
90	if (IS_ERR_VALUE(ret))
91		return ret;
92
93	ret = regmap_update_bits(regmap, SKY81452_REG1, SKY81452_EN,
94					value << CTZ(SKY81452_EN));
95	if (IS_ERR_VALUE(ret))
96		return ret;
97
98	return count;
99}
100
101static ssize_t sky81452_bl_show_open_short(struct device *dev,
102		struct device_attribute *attr, char *buf)
103{
104	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
105	unsigned int reg, value = 0;
106	char tmp[3];
107	int i, ret;
108
109	reg = !strcmp(attr->attr.name, "open") ? SKY81452_REG5 : SKY81452_REG4;
110	ret = regmap_read(regmap, reg, &value);
111	if (IS_ERR_VALUE(ret))
112		return ret;
113
114	if (value & SKY81452_SHRT) {
115		*buf = 0;
116		for (i = 0; i < 6; i++) {
117			if (value & 0x01) {
118				sprintf(tmp, "%d ", i + 1);
119				strcat(buf, tmp);
120			}
121			value >>= 1;
122		}
123		strcat(buf, "\n");
124	} else {
125		strcpy(buf, "none\n");
126	}
127
128	return strlen(buf);
129}
130
131static ssize_t sky81452_bl_show_fault(struct device *dev,
132		struct device_attribute *attr, char *buf)
133{
134	struct regmap *regmap = bl_get_data(to_backlight_device(dev));
135	unsigned int value = 0;
136	int ret;
137
138	ret = regmap_read(regmap, SKY81452_REG4, &value);
139	if (IS_ERR_VALUE(ret))
140		return ret;
141
142	*buf = 0;
143
144	if (value & SKY81452_OCP)
145		strcat(buf, "over-current ");
146
147	if (value & SKY81452_OTMP)
148		strcat(buf, "over-temperature");
149
150	strcat(buf, "\n");
151	return strlen(buf);
152}
153
154static DEVICE_ATTR(enable, S_IWGRP | S_IWUSR, NULL, sky81452_bl_store_enable);
155static DEVICE_ATTR(open, S_IRUGO, sky81452_bl_show_open_short, NULL);
156static DEVICE_ATTR(short, S_IRUGO, sky81452_bl_show_open_short, NULL);
157static DEVICE_ATTR(fault, S_IRUGO, sky81452_bl_show_fault, NULL);
158
159static struct attribute *sky81452_bl_attribute[] = {
160	&dev_attr_enable.attr,
161	&dev_attr_open.attr,
162	&dev_attr_short.attr,
163	&dev_attr_fault.attr,
164	NULL
165};
166
167static const struct attribute_group sky81452_bl_attr_group = {
168	.attrs = sky81452_bl_attribute,
169};
170
171#ifdef CONFIG_OF
172static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
173							struct device *dev)
174{
175	struct device_node *np = of_node_get(dev->of_node);
176	struct sky81452_bl_platform_data *pdata;
177	int num_entry;
178	unsigned int sources[6];
179	int ret;
180
181	if (!np) {
182		dev_err(dev, "backlight node not found.\n");
183		return ERR_PTR(-ENODATA);
184	}
185
186	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
187	if (!pdata) {
188		of_node_put(np);
189		return ERR_PTR(-ENOMEM);
190	}
191
192	of_property_read_string(np, "name", &pdata->name);
193	pdata->ignore_pwm = of_property_read_bool(np, "skyworks,ignore-pwm");
194	pdata->dpwm_mode = of_property_read_bool(np, "skyworks,dpwm-mode");
195	pdata->phase_shift = of_property_read_bool(np, "skyworks,phase-shift");
196	pdata->gpio_enable = of_get_gpio(np, 0);
197
198	ret = of_property_count_u32_elems(np, "led-sources");
199	if (IS_ERR_VALUE(ret)) {
200		pdata->enable = SKY81452_EN >> CTZ(SKY81452_EN);
201	} else {
202		num_entry = ret;
203		if (num_entry > 6)
204			num_entry = 6;
205
206		ret = of_property_read_u32_array(np, "led-sources", sources,
207					num_entry);
208		if (IS_ERR_VALUE(ret)) {
209			dev_err(dev, "led-sources node is invalid.\n");
210			return ERR_PTR(-EINVAL);
211		}
212
213		pdata->enable = 0;
214		while (--num_entry)
215			pdata->enable |= (1 << sources[num_entry]);
216	}
217
218	ret = of_property_read_u32(np,
219			"skyworks,short-detection-threshold-volt",
220			&pdata->short_detection_threshold);
221	if (IS_ERR_VALUE(ret))
222		pdata->short_detection_threshold = 7;
223
224	ret = of_property_read_u32(np, "skyworks,current-limit-mA",
225			&pdata->boost_current_limit);
226	if (IS_ERR_VALUE(ret))
227		pdata->boost_current_limit = 2750;
228
229	of_node_put(np);
230	return pdata;
231}
232#else
233static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
234							struct device *dev)
235{
236	return ERR_PTR(-EINVAL);
237}
238#endif
239
240static int sky81452_bl_init_device(struct regmap *regmap,
241		struct sky81452_bl_platform_data *pdata)
242{
243	unsigned int value;
244
245	value = pdata->ignore_pwm ? SKY81452_IGPW : 0;
246	value |= pdata->dpwm_mode ? SKY81452_PWMMD : 0;
247	value |= pdata->phase_shift ? 0 : SKY81452_PHASE;
248
249	if (pdata->boost_current_limit == 2300)
250		value |= SKY81452_ILIM;
251	else if (pdata->boost_current_limit != 2750)
252		return -EINVAL;
253
254	if (pdata->short_detection_threshold < 4 ||
255				pdata->short_detection_threshold > 7)
256		return -EINVAL;
257	value |= (7 - pdata->short_detection_threshold) << CTZ(SKY81452_VSHRT);
258
259	return regmap_write(regmap, SKY81452_REG2, value);
260}
261
262static int sky81452_bl_probe(struct platform_device *pdev)
263{
264	struct device *dev = &pdev->dev;
265	struct regmap *regmap = dev_get_drvdata(dev->parent);
266	struct sky81452_bl_platform_data *pdata = dev_get_platdata(dev);
267	struct backlight_device *bd;
268	struct backlight_properties props;
269	const char *name;
270	int ret;
271
272	if (!pdata) {
273		pdata = sky81452_bl_parse_dt(dev);
274		if (IS_ERR(pdata))
275			return PTR_ERR(pdata);
276	}
277
278	if (gpio_is_valid(pdata->gpio_enable)) {
279		ret = devm_gpio_request_one(dev, pdata->gpio_enable,
280					GPIOF_OUT_INIT_HIGH, "sky81452-en");
281		if (IS_ERR_VALUE(ret)) {
282			dev_err(dev, "failed to request GPIO. err=%d\n", ret);
283			return ret;
284		}
285	}
286
287	ret = sky81452_bl_init_device(regmap, pdata);
288	if (IS_ERR_VALUE(ret)) {
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 (IS_ERR_VALUE(ret)) {
307		dev_err(dev, "failed to create attribute. err=%d\n", ret);
308		return ret;
309	}
310
311	return ret;
312}
313
314static 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 (gpio_is_valid(pdata->gpio_enable))
327		gpio_set_value_cansleep(pdata->gpio_enable, 0);
328
329	return 0;
330}
331
332#ifdef CONFIG_OF
333static const struct of_device_id sky81452_bl_of_match[] = {
334	{ .compatible = "skyworks,sky81452-backlight", },
335	{ }
336};
337MODULE_DEVICE_TABLE(of, sky81452_bl_of_match);
338#endif
339
340static 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
349module_platform_driver(sky81452_bl_driver);
350
351MODULE_DESCRIPTION("Skyworks SKY81452 backlight driver");
352MODULE_AUTHOR("Gyungoh Yoo <jack.yoo@skyworksinc.com>");
353MODULE_LICENSE("GPL v2");
354