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 	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 
223 static 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 
230 static 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 
247 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
248 
249 static struct attribute *lp8788_attributes[] = {
250 	&dev_attr_bl_ctl_mode.attr,
251 	NULL,
252 };
253 
254 static const struct attribute_group lp8788_attr_group = {
255 	.attrs = lp8788_attributes,
256 };
257 
258 static 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 
296 err_sysfs:
297 	lp8788_backlight_unregister(bl);
298 err_dev:
299 	return ret;
300 }
301 
302 static 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 
313 static 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 };
320 module_platform_driver(lp8788_bl_driver);
321 
322 MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");
323 MODULE_AUTHOR("Milo Kim");
324 MODULE_LICENSE("GPL");
325 MODULE_ALIAS("platform:lp8788-backlight");
326