1/*
2 * TI LP8788 MFD - backlight driver
3 *
4 * Copyright 2012 Texas Instruments
5 *
6 * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 */
13
14#include <linux/backlight.h>
15#include <linux/err.h>
16#include <linux/mfd/lp8788.h>
17#include <linux/module.h>
18#include <linux/platform_device.h>
19#include <linux/pwm.h>
20#include <linux/slab.h>
21
22/* Register address */
23#define LP8788_BL_CONFIG		0x96
24#define LP8788_BL_EN			BIT(0)
25#define LP8788_BL_PWM_INPUT_EN		BIT(5)
26#define LP8788_BL_FULLSCALE_SHIFT	2
27#define LP8788_BL_DIM_MODE_SHIFT	1
28#define LP8788_BL_PWM_POLARITY_SHIFT	6
29
30#define LP8788_BL_BRIGHTNESS		0x97
31
32#define LP8788_BL_RAMP			0x98
33#define LP8788_BL_RAMP_RISE_SHIFT	4
34
35#define MAX_BRIGHTNESS			127
36#define DEFAULT_BL_NAME			"lcd-backlight"
37
38struct lp8788_bl_config {
39	enum lp8788_bl_ctrl_mode bl_mode;
40	enum lp8788_bl_dim_mode dim_mode;
41	enum lp8788_bl_full_scale_current full_scale;
42	enum lp8788_bl_ramp_step rise_time;
43	enum lp8788_bl_ramp_step fall_time;
44	enum pwm_polarity pwm_pol;
45};
46
47struct lp8788_bl {
48	struct lp8788 *lp;
49	struct backlight_device *bl_dev;
50	struct lp8788_backlight_platform_data *pdata;
51	enum lp8788_bl_ctrl_mode mode;
52	struct pwm_device *pwm;
53};
54
55static struct lp8788_bl_config default_bl_config = {
56	.bl_mode    = LP8788_BL_REGISTER_ONLY,
57	.dim_mode   = LP8788_DIM_EXPONENTIAL,
58	.full_scale = LP8788_FULLSCALE_1900uA,
59	.rise_time  = LP8788_RAMP_8192us,
60	.fall_time  = LP8788_RAMP_8192us,
61	.pwm_pol    = PWM_POLARITY_NORMAL,
62};
63
64static inline bool is_brightness_ctrl_by_pwm(enum lp8788_bl_ctrl_mode mode)
65{
66	return mode == LP8788_BL_COMB_PWM_BASED;
67}
68
69static inline bool is_brightness_ctrl_by_register(enum lp8788_bl_ctrl_mode mode)
70{
71	return mode == LP8788_BL_REGISTER_ONLY ||
72		mode == LP8788_BL_COMB_REGISTER_BASED;
73}
74
75static int lp8788_backlight_configure(struct lp8788_bl *bl)
76{
77	struct lp8788_backlight_platform_data *pdata = bl->pdata;
78	struct lp8788_bl_config *cfg = &default_bl_config;
79	int ret;
80	u8 val;
81
82	/*
83	 * Update chip configuration if platform data exists,
84	 * otherwise use the default settings.
85	 */
86	if (pdata) {
87		cfg->bl_mode    = pdata->bl_mode;
88		cfg->dim_mode   = pdata->dim_mode;
89		cfg->full_scale = pdata->full_scale;
90		cfg->rise_time  = pdata->rise_time;
91		cfg->fall_time  = pdata->fall_time;
92		cfg->pwm_pol    = pdata->pwm_pol;
93	}
94
95	/* Brightness ramp up/down */
96	val = (cfg->rise_time << LP8788_BL_RAMP_RISE_SHIFT) | cfg->fall_time;
97	ret = lp8788_write_byte(bl->lp, LP8788_BL_RAMP, val);
98	if (ret)
99		return ret;
100
101	/* Fullscale current setting */
102	val = (cfg->full_scale << LP8788_BL_FULLSCALE_SHIFT) |
103		(cfg->dim_mode << LP8788_BL_DIM_MODE_SHIFT);
104
105	/* Brightness control mode */
106	switch (cfg->bl_mode) {
107	case LP8788_BL_REGISTER_ONLY:
108		val |= LP8788_BL_EN;
109		break;
110	case LP8788_BL_COMB_PWM_BASED:
111	case LP8788_BL_COMB_REGISTER_BASED:
112		val |= LP8788_BL_EN | LP8788_BL_PWM_INPUT_EN |
113			(cfg->pwm_pol << LP8788_BL_PWM_POLARITY_SHIFT);
114		break;
115	default:
116		dev_err(bl->lp->dev, "invalid mode: %d\n", cfg->bl_mode);
117		return -EINVAL;
118	}
119
120	bl->mode = cfg->bl_mode;
121
122	return lp8788_write_byte(bl->lp, LP8788_BL_CONFIG, val);
123}
124
125static void lp8788_pwm_ctrl(struct lp8788_bl *bl, int br, int max_br)
126{
127	unsigned int period;
128	unsigned int duty;
129	struct device *dev;
130	struct pwm_device *pwm;
131
132	if (!bl->pdata)
133		return;
134
135	period = bl->pdata->period_ns;
136	duty = br * period / max_br;
137	dev = bl->lp->dev;
138
139	/* request PWM device with the consumer name */
140	if (!bl->pwm) {
141		pwm = devm_pwm_get(dev, LP8788_DEV_BACKLIGHT);
142		if (IS_ERR(pwm)) {
143			dev_err(dev, "can not get PWM device\n");
144			return;
145		}
146
147		bl->pwm = pwm;
148	}
149
150	pwm_config(bl->pwm, duty, period);
151	if (duty)
152		pwm_enable(bl->pwm);
153	else
154		pwm_disable(bl->pwm);
155}
156
157static int lp8788_bl_update_status(struct backlight_device *bl_dev)
158{
159	struct lp8788_bl *bl = bl_get_data(bl_dev);
160	enum lp8788_bl_ctrl_mode mode = bl->mode;
161
162	if (bl_dev->props.state & BL_CORE_SUSPENDED)
163		bl_dev->props.brightness = 0;
164
165	if (is_brightness_ctrl_by_pwm(mode)) {
166		int brt = bl_dev->props.brightness;
167		int max = bl_dev->props.max_brightness;
168
169		lp8788_pwm_ctrl(bl, brt, max);
170	} else if (is_brightness_ctrl_by_register(mode)) {
171		u8 brt = bl_dev->props.brightness;
172
173		lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, brt);
174	}
175
176	return 0;
177}
178
179static const struct backlight_ops lp8788_bl_ops = {
180	.options = BL_CORE_SUSPENDRESUME,
181	.update_status = lp8788_bl_update_status,
182};
183
184static int lp8788_backlight_register(struct lp8788_bl *bl)
185{
186	struct backlight_device *bl_dev;
187	struct backlight_properties props;
188	struct lp8788_backlight_platform_data *pdata = bl->pdata;
189	int init_brt;
190	char *name;
191
192	props.type = BACKLIGHT_PLATFORM;
193	props.max_brightness = MAX_BRIGHTNESS;
194
195	/* Initial brightness */
196	if (pdata)
197		init_brt = min_t(int, pdata->initial_brightness,
198				props.max_brightness);
199	else
200		init_brt = 0;
201
202	props.brightness = init_brt;
203
204	/* Backlight device name */
205	if (!pdata || !pdata->name)
206		name = DEFAULT_BL_NAME;
207	else
208		name = pdata->name;
209
210	bl_dev = backlight_device_register(name, bl->lp->dev, bl,
211				       &lp8788_bl_ops, &props);
212	if (IS_ERR(bl_dev))
213		return PTR_ERR(bl_dev);
214
215	bl->bl_dev = bl_dev;
216
217	return 0;
218}
219
220static void lp8788_backlight_unregister(struct lp8788_bl *bl)
221{
222	struct backlight_device *bl_dev = bl->bl_dev;
223
224	if (bl_dev)
225		backlight_device_unregister(bl_dev);
226}
227
228static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,
229				     struct device_attribute *attr, char *buf)
230{
231	struct lp8788_bl *bl = dev_get_drvdata(dev);
232	enum lp8788_bl_ctrl_mode mode = bl->mode;
233	char *strmode;
234
235	if (is_brightness_ctrl_by_pwm(mode))
236		strmode = "PWM based";
237	else if (is_brightness_ctrl_by_register(mode))
238		strmode = "Register based";
239	else
240		strmode = "Invalid mode";
241
242	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
243}
244
245static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
246
247static struct attribute *lp8788_attributes[] = {
248	&dev_attr_bl_ctl_mode.attr,
249	NULL,
250};
251
252static const struct attribute_group lp8788_attr_group = {
253	.attrs = lp8788_attributes,
254};
255
256static int lp8788_backlight_probe(struct platform_device *pdev)
257{
258	struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
259	struct lp8788_bl *bl;
260	int ret;
261
262	bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);
263	if (!bl)
264		return -ENOMEM;
265
266	bl->lp = lp;
267	if (lp->pdata)
268		bl->pdata = lp->pdata->bl_pdata;
269
270	platform_set_drvdata(pdev, bl);
271
272	ret = lp8788_backlight_configure(bl);
273	if (ret) {
274		dev_err(lp->dev, "backlight config err: %d\n", ret);
275		goto err_dev;
276	}
277
278	ret = lp8788_backlight_register(bl);
279	if (ret) {
280		dev_err(lp->dev, "register backlight err: %d\n", ret);
281		goto err_dev;
282	}
283
284	ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);
285	if (ret) {
286		dev_err(lp->dev, "register sysfs err: %d\n", ret);
287		goto err_sysfs;
288	}
289
290	backlight_update_status(bl->bl_dev);
291
292	return 0;
293
294err_sysfs:
295	lp8788_backlight_unregister(bl);
296err_dev:
297	return ret;
298}
299
300static int lp8788_backlight_remove(struct platform_device *pdev)
301{
302	struct lp8788_bl *bl = platform_get_drvdata(pdev);
303	struct backlight_device *bl_dev = bl->bl_dev;
304
305	bl_dev->props.brightness = 0;
306	backlight_update_status(bl_dev);
307	sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);
308	lp8788_backlight_unregister(bl);
309
310	return 0;
311}
312
313static struct platform_driver lp8788_bl_driver = {
314	.probe = lp8788_backlight_probe,
315	.remove = lp8788_backlight_remove,
316	.driver = {
317		.name = LP8788_DEV_BACKLIGHT,
318	},
319};
320module_platform_driver(lp8788_bl_driver);
321
322MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");
323MODULE_AUTHOR("Milo Kim");
324MODULE_LICENSE("GPL");
325MODULE_ALIAS("platform:lp8788-backlight");
326