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 
34 struct 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 
43 struct 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 
51 static 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 
60 static inline bool is_brightness_ctrl_by_pwm(enum lp8788_bl_ctrl_mode mode)
61 {
62 	return mode == LP8788_BL_COMB_PWM_BASED;
63 }
64 
65 static 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 
71 static 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 
121 static 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 
159 static 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 
181 static const struct backlight_ops lp8788_bl_ops = {
182 	.options = BL_CORE_SUSPENDRESUME,
183 	.update_status = lp8788_bl_update_status,
184 };
185 
186 static 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 	props.type = BACKLIGHT_PLATFORM;
195 	props.max_brightness = MAX_BRIGHTNESS;
196 
197 	/* Initial brightness */
198 	if (pdata)
199 		init_brt = min_t(int, pdata->initial_brightness,
200 				props.max_brightness);
201 	else
202 		init_brt = 0;
203 
204 	props.brightness = init_brt;
205 
206 	/* Backlight device name */
207 	if (!pdata || !pdata->name)
208 		name = DEFAULT_BL_NAME;
209 	else
210 		name = pdata->name;
211 
212 	bl_dev = backlight_device_register(name, bl->lp->dev, bl,
213 				       &lp8788_bl_ops, &props);
214 	if (IS_ERR(bl_dev))
215 		return PTR_ERR(bl_dev);
216 
217 	bl->bl_dev = bl_dev;
218 
219 	return 0;
220 }
221 
222 static void lp8788_backlight_unregister(struct lp8788_bl *bl)
223 {
224 	struct backlight_device *bl_dev = bl->bl_dev;
225 
226 	backlight_device_unregister(bl_dev);
227 }
228 
229 static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,
230 				     struct device_attribute *attr, char *buf)
231 {
232 	struct lp8788_bl *bl = dev_get_drvdata(dev);
233 	enum lp8788_bl_ctrl_mode mode = bl->mode;
234 	char *strmode;
235 
236 	if (is_brightness_ctrl_by_pwm(mode))
237 		strmode = "PWM based";
238 	else if (is_brightness_ctrl_by_register(mode))
239 		strmode = "Register based";
240 	else
241 		strmode = "Invalid mode";
242 
243 	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
244 }
245 
246 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
247 
248 static struct attribute *lp8788_attributes[] = {
249 	&dev_attr_bl_ctl_mode.attr,
250 	NULL,
251 };
252 
253 static const struct attribute_group lp8788_attr_group = {
254 	.attrs = lp8788_attributes,
255 };
256 
257 static int lp8788_backlight_probe(struct platform_device *pdev)
258 {
259 	struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
260 	struct lp8788_bl *bl;
261 	int ret;
262 
263 	bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);
264 	if (!bl)
265 		return -ENOMEM;
266 
267 	bl->lp = lp;
268 	if (lp->pdata)
269 		bl->pdata = lp->pdata->bl_pdata;
270 
271 	platform_set_drvdata(pdev, bl);
272 
273 	ret = lp8788_backlight_configure(bl);
274 	if (ret) {
275 		dev_err(lp->dev, "backlight config err: %d\n", ret);
276 		goto err_dev;
277 	}
278 
279 	ret = lp8788_backlight_register(bl);
280 	if (ret) {
281 		dev_err(lp->dev, "register backlight err: %d\n", ret);
282 		goto err_dev;
283 	}
284 
285 	ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);
286 	if (ret) {
287 		dev_err(lp->dev, "register sysfs err: %d\n", ret);
288 		goto err_sysfs;
289 	}
290 
291 	backlight_update_status(bl->bl_dev);
292 
293 	return 0;
294 
295 err_sysfs:
296 	lp8788_backlight_unregister(bl);
297 err_dev:
298 	return ret;
299 }
300 
301 static void lp8788_backlight_remove(struct platform_device *pdev)
302 {
303 	struct lp8788_bl *bl = platform_get_drvdata(pdev);
304 	struct backlight_device *bl_dev = bl->bl_dev;
305 
306 	bl_dev->props.brightness = 0;
307 	backlight_update_status(bl_dev);
308 	sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);
309 	lp8788_backlight_unregister(bl);
310 }
311 
312 static struct platform_driver lp8788_bl_driver = {
313 	.probe = lp8788_backlight_probe,
314 	.remove_new = lp8788_backlight_remove,
315 	.driver = {
316 		.name = LP8788_DEV_BACKLIGHT,
317 	},
318 };
319 module_platform_driver(lp8788_bl_driver);
320 
321 MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");
322 MODULE_AUTHOR("Milo Kim");
323 MODULE_LICENSE("GPL");
324 MODULE_ALIAS("platform:lp8788-backlight");
325