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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
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
84
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
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
102 val = (cfg->full_scale << LP8788_BL_FULLSCALE_SHIFT) |
103 (cfg->dim_mode << LP8788_BL_DIM_MODE_SHIFT);
104
105
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
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
151
152
153 pwm_apply_args(pwm);
154 }
155
156 pwm_config(bl->pwm, duty, period);
157 if (duty)
158 pwm_enable(bl->pwm);
159 else
160 pwm_disable(bl->pwm);
161}
162
163static int lp8788_bl_update_status(struct backlight_device *bl_dev)
164{
165 struct lp8788_bl *bl = bl_get_data(bl_dev);
166 enum lp8788_bl_ctrl_mode mode = bl->mode;
167
168 if (bl_dev->props.state & BL_CORE_SUSPENDED)
169 bl_dev->props.brightness = 0;
170
171 if (is_brightness_ctrl_by_pwm(mode)) {
172 int brt = bl_dev->props.brightness;
173 int max = bl_dev->props.max_brightness;
174
175 lp8788_pwm_ctrl(bl, brt, max);
176 } else if (is_brightness_ctrl_by_register(mode)) {
177 u8 brt = bl_dev->props.brightness;
178
179 lp8788_write_byte(bl->lp, LP8788_BL_BRIGHTNESS, brt);
180 }
181
182 return 0;
183}
184
185static const struct backlight_ops lp8788_bl_ops = {
186 .options = BL_CORE_SUSPENDRESUME,
187 .update_status = lp8788_bl_update_status,
188};
189
190static int lp8788_backlight_register(struct lp8788_bl *bl)
191{
192 struct backlight_device *bl_dev;
193 struct backlight_properties props;
194 struct lp8788_backlight_platform_data *pdata = bl->pdata;
195 int init_brt;
196 char *name;
197
198 props.type = BACKLIGHT_PLATFORM;
199 props.max_brightness = MAX_BRIGHTNESS;
200
201
202 if (pdata)
203 init_brt = min_t(int, pdata->initial_brightness,
204 props.max_brightness);
205 else
206 init_brt = 0;
207
208 props.brightness = init_brt;
209
210
211 if (!pdata || !pdata->name)
212 name = DEFAULT_BL_NAME;
213 else
214 name = pdata->name;
215
216 bl_dev = backlight_device_register(name, bl->lp->dev, bl,
217 &lp8788_bl_ops, &props);
218 if (IS_ERR(bl_dev))
219 return PTR_ERR(bl_dev);
220
221 bl->bl_dev = bl_dev;
222
223 return 0;
224}
225
226static void lp8788_backlight_unregister(struct lp8788_bl *bl)
227{
228 struct backlight_device *bl_dev = bl->bl_dev;
229
230 backlight_device_unregister(bl_dev);
231}
232
233static ssize_t lp8788_get_bl_ctl_mode(struct device *dev,
234 struct device_attribute *attr, char *buf)
235{
236 struct lp8788_bl *bl = dev_get_drvdata(dev);
237 enum lp8788_bl_ctrl_mode mode = bl->mode;
238 char *strmode;
239
240 if (is_brightness_ctrl_by_pwm(mode))
241 strmode = "PWM based";
242 else if (is_brightness_ctrl_by_register(mode))
243 strmode = "Register based";
244 else
245 strmode = "Invalid mode";
246
247 return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
248}
249
250static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp8788_get_bl_ctl_mode, NULL);
251
252static struct attribute *lp8788_attributes[] = {
253 &dev_attr_bl_ctl_mode.attr,
254 NULL,
255};
256
257static const struct attribute_group lp8788_attr_group = {
258 .attrs = lp8788_attributes,
259};
260
261static int lp8788_backlight_probe(struct platform_device *pdev)
262{
263 struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
264 struct lp8788_bl *bl;
265 int ret;
266
267 bl = devm_kzalloc(lp->dev, sizeof(struct lp8788_bl), GFP_KERNEL);
268 if (!bl)
269 return -ENOMEM;
270
271 bl->lp = lp;
272 if (lp->pdata)
273 bl->pdata = lp->pdata->bl_pdata;
274
275 platform_set_drvdata(pdev, bl);
276
277 ret = lp8788_backlight_configure(bl);
278 if (ret) {
279 dev_err(lp->dev, "backlight config err: %d\n", ret);
280 goto err_dev;
281 }
282
283 ret = lp8788_backlight_register(bl);
284 if (ret) {
285 dev_err(lp->dev, "register backlight err: %d\n", ret);
286 goto err_dev;
287 }
288
289 ret = sysfs_create_group(&pdev->dev.kobj, &lp8788_attr_group);
290 if (ret) {
291 dev_err(lp->dev, "register sysfs err: %d\n", ret);
292 goto err_sysfs;
293 }
294
295 backlight_update_status(bl->bl_dev);
296
297 return 0;
298
299err_sysfs:
300 lp8788_backlight_unregister(bl);
301err_dev:
302 return ret;
303}
304
305static int lp8788_backlight_remove(struct platform_device *pdev)
306{
307 struct lp8788_bl *bl = platform_get_drvdata(pdev);
308 struct backlight_device *bl_dev = bl->bl_dev;
309
310 bl_dev->props.brightness = 0;
311 backlight_update_status(bl_dev);
312 sysfs_remove_group(&pdev->dev.kobj, &lp8788_attr_group);
313 lp8788_backlight_unregister(bl);
314
315 return 0;
316}
317
318static struct platform_driver lp8788_bl_driver = {
319 .probe = lp8788_backlight_probe,
320 .remove = lp8788_backlight_remove,
321 .driver = {
322 .name = LP8788_DEV_BACKLIGHT,
323 },
324};
325module_platform_driver(lp8788_bl_driver);
326
327MODULE_DESCRIPTION("Texas Instruments LP8788 Backlight Driver");
328MODULE_AUTHOR("Milo Kim");
329MODULE_LICENSE("GPL");
330MODULE_ALIAS("platform:lp8788-backlight");
331
