1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * TI LP8788 MFD - backlight driver
4 *
5 * Copyright 2012 Texas Instruments
6 *
7 * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
8 */
9
10#include <linux/backlight.h>
11#include <linux/err.h>
12#include <linux/mfd/lp8788.h>
13#include <linux/module.h>
14#include <linux/platform_device.h>
15#include <linux/pwm.h>
16#include <linux/slab.h>
17
18/* Register address */
19#define LP8788_BL_CONFIG		0x96
20#define LP8788_BL_EN			BIT(0)
21#define LP8788_BL_PWM_INPUT_EN		BIT(5)
22#define LP8788_BL_FULLSCALE_SHIFT	2
23#define LP8788_BL_DIM_MODE_SHIFT	1
24#define LP8788_BL_PWM_POLARITY_SHIFT	6
25
26#define LP8788_BL_BRIGHTNESS		0x97
27
28#define LP8788_BL_RAMP			0x98
29#define LP8788_BL_RAMP_RISE_SHIFT	4
30
31#define MAX_BRIGHTNESS			127
32#define DEFAULT_BL_NAME			"lcd-backlight"
33
34struct lp8788_bl_config {
35	enum lp8788_bl_ctrl_mode bl_mode;
36	enum lp8788_bl_dim_mode dim_mode;
37	enum lp8788_bl_full_scale_current full_scale;
38	enum lp8788_bl_ramp_step rise_time;
39	enum lp8788_bl_ramp_step fall_time;
40	enum pwm_polarity pwm_pol;
41};
42
43struct lp8788_bl {
44	struct lp8788 *lp;
45	struct backlight_device *bl_dev;
46	struct lp8788_backlight_platform_data *pdata;
47	enum lp8788_bl_ctrl_mode mode;
48	struct pwm_device *pwm;
49};
50
51static struct lp8788_bl_config default_bl_config = {
52	.bl_mode    = LP8788_BL_REGISTER_ONLY,
53	.dim_mode   = LP8788_DIM_EXPONENTIAL,
54	.full_scale = LP8788_FULLSCALE_1900uA,
55	.rise_time  = LP8788_RAMP_8192us,
56	.fall_time  = LP8788_RAMP_8192us,
57	.pwm_pol    = PWM_POLARITY_NORMAL,
58};
59
60static inline bool is_brightness_ctrl_by_pwm(enum lp8788_bl_ctrl_mode mode)
61{
62	return mode == LP8788_BL_COMB_PWM_BASED;
63}
64
65static inline bool is_brightness_ctrl_by_register(enum lp8788_bl_ctrl_mode mode)
66{
67	return mode == LP8788_BL_REGISTER_ONLY ||
68		mode == LP8788_BL_COMB_REGISTER_BASED;
69}
70
71static int lp8788_backlight_configure(struct lp8788_bl *bl)
72{
73	struct lp8788_backlight_platform_data *pdata = bl->pdata;
74	struct lp8788_bl_config *cfg = &default_bl_config;
75	int ret;
76	u8 val;
77
78	/*
79	 * Update chip configuration if platform data exists,
80	 * otherwise use the default settings.
81	 */
82	if (pdata) {
83		cfg->bl_mode    = pdata->bl_mode;
84		cfg->dim_mode   = pdata->dim_mode;
85		cfg->full_scale = pdata->full_scale;
86		cfg->rise_time  = pdata->rise_time;
87		cfg->fall_time  = pdata->fall_time;
88		cfg->pwm_pol    = pdata->pwm_pol;
89	}
90
91	/* Brightness ramp up/down */
92	val = (cfg->rise_time << LP8788_BL_RAMP_RISE_SHIFT) | cfg->fall_time;
93	ret = lp8788_write_byte(bl->lp, LP8788_BL_RAMP, val);
94	if (ret)
95		return ret;
96
97	/* Fullscale current setting */
98	val = (cfg->full_scale << LP8788_BL_FULLSCALE_SHIFT) |
99		(cfg->dim_mode << LP8788_BL_DIM_MODE_SHIFT);
100
101	/* Brightness control mode */
102	switch (cfg->bl_mode) {
103	case LP8788_BL_REGISTER_ONLY:
104		val |= LP8788_BL_EN;
105		break;
106	case LP8788_BL_COMB_PWM_BASED:
107	case LP8788_BL_COMB_REGISTER_BASED:
108		val |= LP8788_BL_EN | LP8788_BL_PWM_INPUT_EN |
109			(cfg->pwm_pol << LP8788_BL_PWM_POLARITY_SHIFT);
110		break;
111	default:
112		dev_err(bl->lp->dev, "invalid mode: %d\n", cfg->bl_mode);
113		return -EINVAL;
114	}
115
116	bl->mode = cfg->bl_mode;
117
118	return lp8788_write_byte(bl->lp, LP8788_BL_CONFIG, val);
119}
120
121static void lp8788_pwm_ctrl(struct lp8788_bl *bl, int br, int max_br)
122{
123	unsigned int period;
124	unsigned int duty;
125	struct device *dev;
126	struct pwm_device *pwm;
127
128	if (!bl->pdata)
129		return;
130
131	period = bl->pdata->period_ns;
132	duty = br * period / max_br;
133	dev = bl->lp->dev;
134
135	/* request PWM device with the consumer name */
136	if (!bl->pwm) {
137		pwm = devm_pwm_get(dev, LP8788_DEV_BACKLIGHT);
138		if (IS_ERR(pwm)) {
139			dev_err(dev, "can not get PWM device\n");
140			return;
141		}
142
143		bl->pwm = pwm;
144
145		/*
146		 * FIXME: pwm_apply_args() should be removed when switching to
147		 * the atomic PWM API.
148		 */
149		pwm_apply_args(pwm);
150	}
151
152	pwm_config(bl->pwm, duty, period);
153	if (duty)
154		pwm_enable(bl->pwm);
155	else
156		pwm_disable(bl->pwm);
157}
158
159static int lp8788_bl_update_status(struct backlight_device *bl_dev)
160{
161	struct lp8788_bl *bl = bl_get_data(bl_dev);
162	enum lp8788_bl_ctrl_mode mode = bl->mode;
163
164	if (bl_dev->props.state & BL_CORE_SUSPENDED)
165		bl_dev->props.brightness = 0;
166
167	if (is_brightness_ctrl_by_pwm(mode)) {
168		int brt = bl_dev->props.brightness;
169		int max = bl_dev->props.max_brightness;
170
171		lp8788_pwm_ctrl(bl, brt, max);
172	} else if (is_brightness_ctrl_by_register(mode)) {
173		u8 brt = bl_dev->props.brightness;
174
175		lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, brt);
176	}
177
178	return 0;
179}
180
181static const struct backlight_ops lp8788_bl_ops = {
182	.options = BL_CORE_SUSPENDRESUME,
183	.update_status = lp8788_bl_update_status,
184};
185
186static int lp8788_backlight_register(struct lp8788_bl *bl)
187{
188	struct backlight_device *bl_dev;
189	struct backlight_properties props;
190	struct lp8788_backlight_platform_data *pdata = bl->pdata;
191	int init_brt;
192	char *name;
193
194	memset(&props, 0, sizeof(struct backlight_properties));
195	props.type = BACKLIGHT_PLATFORM;
196	props.max_brightness = MAX_BRIGHTNESS;
197
198	/* Initial brightness */
199	if (pdata)
200		init_brt = min_t(int, pdata->initial_brightness,
201				props.max_brightness);
202	else
203		init_brt = 0;
204
205	props.brightness = init_brt;
206
207	/* Backlight device name */
208	if (!pdata || !pdata->name)
209		name = DEFAULT_BL_NAME;
210	else
211		name = pdata->name;
212
213	bl_dev = backlight_device_register(name, bl->lp->dev, bl,
214				       &lp8788_bl_ops, &props);
215	if (IS_ERR(bl_dev))
216		return PTR_ERR(bl_dev);
217
218	bl->bl_dev = bl_dev;
219
220	return 0;
221}
222
223static void lp8788_backlight_unregister(struct lp8788_bl *bl)
224{
225	struct backlight_device *bl_dev = bl->bl_dev;
226
227	backlight_device_unregister(bl_dev);
228}
229
230static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,
231				     struct device_attribute *attr, char *buf)
232{
233	struct lp8788_bl *bl = dev_get_drvdata(dev);
234	enum lp8788_bl_ctrl_mode mode = bl->mode;
235	char *strmode;
236
237	if (is_brightness_ctrl_by_pwm(mode))
238		strmode = "PWM based";
239	else if (is_brightness_ctrl_by_register(mode))
240		strmode = "Register based";
241	else
242		strmode = "Invalid mode";
243
244	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
245}
246
247static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
248
249static struct attribute *lp8788_attributes[] = {
250	&dev_attr_bl_ctl_mode.attr,
251	NULL,
252};
253
254static const struct attribute_group lp8788_attr_group = {
255	.attrs = lp8788_attributes,
256};
257
258static int lp8788_backlight_probe(struct platform_device *pdev)
259{
260	struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
261	struct lp8788_bl *bl;
262	int ret;
263
264	bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);
265	if (!bl)
266		return -ENOMEM;
267
268	bl->lp = lp;
269	if (lp->pdata)
270		bl->pdata = lp->pdata->bl_pdata;
271
272	platform_set_drvdata(pdev, bl);
273
274	ret = lp8788_backlight_configure(bl);
275	if (ret) {
276		dev_err(lp->dev, "backlight config err: %d\n", ret);
277		goto err_dev;
278	}
279
280	ret = lp8788_backlight_register(bl);
281	if (ret) {
282		dev_err(lp->dev, "register backlight err: %d\n", ret);
283		goto err_dev;
284	}
285
286	ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);
287	if (ret) {
288		dev_err(lp->dev, "register sysfs err: %d\n", ret);
289		goto err_sysfs;
290	}
291
292	backlight_update_status(bl->bl_dev);
293
294	return 0;
295
296err_sysfs:
297	lp8788_backlight_unregister(bl);
298err_dev:
299	return ret;
300}
301
302static void lp8788_backlight_remove(struct platform_device *pdev)
303{
304	struct lp8788_bl *bl = platform_get_drvdata(pdev);
305	struct backlight_device *bl_dev = bl->bl_dev;
306
307	bl_dev->props.brightness = 0;
308	backlight_update_status(bl_dev);
309	sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);
310	lp8788_backlight_unregister(bl);
311}
312
313static struct platform_driver lp8788_bl_driver = {
314	.probe = lp8788_backlight_probe,
315	.remove_new = 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