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
is_brightness_ctrl_by_pwm(enum lp8788_bl_ctrl_mode mode)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
is_brightness_ctrl_by_register(enum lp8788_bl_ctrl_mode mode)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
lp8788_backlight_configure(struct lp8788_bl * bl)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
lp8788_pwm_ctrl(struct lp8788_bl * bl,int br,int max_br)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
lp8788_bl_update_status(struct backlight_device * bl_dev)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
lp8788_backlight_register(struct lp8788_bl * bl)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
lp8788_backlight_unregister(struct lp8788_bl * bl)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
lp8788_get_bl_ctl_mode(struct device * dev,struct device_attribute * attr,char * buf)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
lp8788_backlight_probe(struct platform_device * pdev)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
lp8788_backlight_remove(struct platform_device * pdev)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