1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Driver for MPS MP3309C White LED driver with I2C interface
*
* This driver support both analog (by I2C commands) and PWM dimming control
* modes.
*
* Copyright (C) 2023 ASEM Srl
* Author: Flavio Suligoi <f.suligoi@asem.it>
*
* Based on pwm_bl.c
*/
#include <linux/backlight.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
#define REG_I2C_0 0x00
#define REG_I2C_1 0x01
#define REG_I2C_0_EN 0x80
#define REG_I2C_0_D0 0x40
#define REG_I2C_0_D1 0x20
#define REG_I2C_0_D2 0x10
#define REG_I2C_0_D3 0x08
#define REG_I2C_0_D4 0x04
#define REG_I2C_0_RSRV1 0x02
#define REG_I2C_0_RSRV2 0x01
#define REG_I2C_1_RSRV1 0x80
#define REG_I2C_1_DIMS 0x40
#define REG_I2C_1_SYNC 0x20
#define REG_I2C_1_OVP0 0x10
#define REG_I2C_1_OVP1 0x08
#define REG_I2C_1_VOS 0x04
#define REG_I2C_1_LEDO 0x02
#define REG_I2C_1_OTP 0x01
#define ANALOG_I2C_NUM_LEVELS 32 /* 0..31 */
#define ANALOG_I2C_REG_MASK 0x7c
#define MP3309C_PWM_DEFAULT_NUM_LEVELS 256 /* 0..255 */
enum mp3309c_status_value {
FIRST_POWER_ON,
BACKLIGHT_OFF,
BACKLIGHT_ON,
};
enum mp3309c_dimming_mode_value {
DIMMING_PWM,
DIMMING_ANALOG_I2C,
};
struct mp3309c_platform_data {
unsigned int max_brightness;
unsigned int default_brightness;
unsigned int *levels;
u8 dimming_mode;
u8 over_voltage_protection;
bool sync_mode;
u8 status;
};
struct mp3309c_chip {
struct device *dev;
struct mp3309c_platform_data *pdata;
struct backlight_device *bl;
struct gpio_desc *enable_gpio;
struct regmap *regmap;
struct pwm_device *pwmd;
};
static const struct regmap_config mp3309c_regmap = {
.name = "mp3309c_regmap",
.reg_bits = 8,
.reg_stride = 1,
.val_bits = 8,
.max_register = REG_I2C_1,
};
static int mp3309c_enable_device(struct mp3309c_chip *chip)
{
u8 reg_val;
int ret;
/* I2C register #0 - Device enable */
ret = regmap_update_bits(chip->regmap, REG_I2C_0, REG_I2C_0_EN,
REG_I2C_0_EN);
if (ret)
return ret;
/*
* I2C register #1 - Set working mode:
* - set one of the two dimming mode:
* - PWM dimming using an external PWM dimming signal
* - analog dimming using I2C commands
* - enable/disable synchronous mode
* - set overvoltage protection (OVP)
*/
reg_val = 0x00;
if (chip->pdata->dimming_mode == DIMMING_PWM)
reg_val |= REG_I2C_1_DIMS;
if (chip->pdata->sync_mode)
reg_val |= REG_I2C_1_SYNC;
reg_val |= chip->pdata->over_voltage_protection;
ret = regmap_write(chip->regmap, REG_I2C_1, reg_val);
if (ret)
return ret;
return 0;
}
static int mp3309c_bl_update_status(struct backlight_device *bl)
{
struct mp3309c_chip *chip = bl_get_data(bl);
int brightness = backlight_get_brightness(bl);
struct pwm_state pwmstate;
unsigned int analog_val, bits_val;
int i, ret;
if (chip->pdata->dimming_mode == DIMMING_PWM) {
/*
* PWM control mode
*/
pwm_get_state(chip->pwmd, &pwmstate);
pwm_set_relative_duty_cycle(&pwmstate,
chip->pdata->levels[brightness],
chip->pdata->levels[chip->pdata->max_brightness]);
pwmstate.enabled = true;
ret = pwm_apply_might_sleep(chip->pwmd, &pwmstate);
if (ret)
return ret;
switch (chip->pdata->status) {
case FIRST_POWER_ON:
case BACKLIGHT_OFF:
/*
* After 20ms of low pwm signal level, the chip turns
* off automatically. In this case, before enabling the
* chip again, we must wait about 10ms for pwm signal to
* stabilize.
*/
if (brightness > 0) {
msleep(10);
mp3309c_enable_device(chip);
chip->pdata->status = BACKLIGHT_ON;
} else {
chip->pdata->status = BACKLIGHT_OFF;
}
break;
case BACKLIGHT_ON:
if (brightness == 0)
chip->pdata->status = BACKLIGHT_OFF;
break;
}
} else {
/*
* Analog (by I2C command) control mode
*
* The first time, before setting brightness, we must enable the
* device
*/
if (chip->pdata->status == FIRST_POWER_ON)
mp3309c_enable_device(chip);
/*
* Dimming mode I2C command (fixed dimming range 0..31)
*
* The 5 bits of the dimming analog value D4..D0 is allocated
* in the I2C register #0, in the following way:
*
* +--+--+--+--+--+--+--+--+
* |EN|D0|D1|D2|D3|D4|XX|XX|
* +--+--+--+--+--+--+--+--+
*/
analog_val = brightness;
bits_val = 0;
for (i = 0; i <= 5; i++)
bits_val += ((analog_val >> i) & 0x01) << (6 - i);
ret = regmap_update_bits(chip->regmap, REG_I2C_0,
ANALOG_I2C_REG_MASK, bits_val);
if (ret)
return ret;
if (brightness > 0)
chip->pdata->status = BACKLIGHT_ON;
else
chip->pdata->status = BACKLIGHT_OFF;
}
return 0;
}
static const struct backlight_ops mp3309c_bl_ops = {
.update_status = mp3309c_bl_update_status,
};
static int mp3309c_parse_fwnode(struct mp3309c_chip *chip,
struct mp3309c_platform_data *pdata)
{
int ret, i;
unsigned int num_levels, tmp_value;
struct device *dev = chip->dev;
if (!dev_fwnode(dev))
return dev_err_probe(dev, -ENODEV, "failed to get firmware node\n");
/*
* Dimming mode: the MP3309C provides two dimming control mode:
*
* - PWM mode
* - Analog by I2C control mode (default)
*
* I2C control mode is assumed as default but, if the pwms property is
* found in the backlight node, the mode switches to PWM mode.
*/
pdata->dimming_mode = DIMMING_ANALOG_I2C;
if (device_property_present(dev, "pwms")) {
chip->pwmd = devm_pwm_get(chip->dev, NULL);
if (IS_ERR(chip->pwmd))
return dev_err_probe(chip->dev, PTR_ERR(chip->pwmd),
"error getting pwm data\n");
pdata->dimming_mode = DIMMING_PWM;
pwm_apply_args(chip->pwmd);
}
/*
* In I2C control mode the dimming levels (0..31) are fixed by the
* hardware, while in PWM control mode they can be chosen by the user,
* to allow nonlinear mappings.
*/
if (pdata->dimming_mode == DIMMING_ANALOG_I2C) {
/*
* Analog (by I2C commands) control mode: fixed 0..31 brightness
* levels
*/
num_levels = ANALOG_I2C_NUM_LEVELS;
/* Enable GPIO used in I2C dimming mode only */
chip->enable_gpio = devm_gpiod_get(chip->dev, "enable",
GPIOD_OUT_HIGH);
if (IS_ERR(chip->enable_gpio))
return dev_err_probe(chip->dev,
PTR_ERR(chip->enable_gpio),
"error getting enable gpio\n");
} else {
/*
* PWM control mode: check for brightness level in DT
*/
if (device_property_present(dev, "brightness-levels")) {
/* Read brightness levels from DT */
num_levels = device_property_count_u32(dev, "brightness-levels");
if (num_levels < 2)
return -EINVAL;
} else {
/* Use default brightness levels */
num_levels = MP3309C_PWM_DEFAULT_NUM_LEVELS;
}
}
/* Fill brightness levels array */
pdata->levels = devm_kcalloc(chip->dev, num_levels,
sizeof(*pdata->levels), GFP_KERNEL);
if (!pdata->levels)
return -ENOMEM;
if (device_property_present(dev, "brightness-levels")) {
ret = device_property_read_u32_array(dev, "brightness-levels",
pdata->levels, num_levels);
if (ret < 0)
return ret;
} else {
for (i = 0; i < num_levels; i++)
pdata->levels[i] = i;
}
pdata->max_brightness = num_levels - 1;
ret = device_property_read_u32(dev, "default-brightness", &pdata->default_brightness);
if (ret)
pdata->default_brightness = pdata->max_brightness;
if (pdata->default_brightness > pdata->max_brightness) {
dev_err_probe(dev, -ERANGE, "default brightness exceeds max brightness\n");
pdata->default_brightness = pdata->max_brightness;
}
/*
* Over-voltage protection (OVP)
*
* This (optional) property values are:
*
* - 13.5V
* - 24V
* - 35.5V (hardware default setting)
*
* If missing, the default value for OVP is 35.5V
*/
pdata->over_voltage_protection = REG_I2C_1_OVP1;
ret = device_property_read_u32(dev, "mps,overvoltage-protection-microvolt", &tmp_value);
if (!ret) {
switch (tmp_value) {
case 13500000:
pdata->over_voltage_protection = 0x00;
break;
case 24000000:
pdata->over_voltage_protection = REG_I2C_1_OVP0;
break;
case 35500000:
pdata->over_voltage_protection = REG_I2C_1_OVP1;
break;
default:
return -EINVAL;
}
}
/* Synchronous (default) and non-synchronous mode */
pdata->sync_mode = !device_property_read_bool(dev, "mps,no-sync-mode");
return 0;
}
static int mp3309c_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct mp3309c_platform_data *pdata = dev_get_platdata(dev);
struct mp3309c_chip *chip;
struct backlight_properties props;
struct pwm_state pwmstate;
int ret;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return dev_err_probe(dev, -EOPNOTSUPP, "failed to check i2c functionality\n");
chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
chip->dev = &client->dev;
chip->regmap = devm_regmap_init_i2c(client, &mp3309c_regmap);
if (IS_ERR(chip->regmap))
return dev_err_probe(&client->dev, PTR_ERR(chip->regmap),
"failed to allocate register map\n");
i2c_set_clientdata(client, chip);
if (!pdata) {
pdata = devm_kzalloc(chip->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
ret = mp3309c_parse_fwnode(chip, pdata);
if (ret)
return ret;
}
chip->pdata = pdata;
/* Backlight properties */
props.brightness = pdata->default_brightness;
props.max_brightness = pdata->max_brightness;
props.scale = BACKLIGHT_SCALE_LINEAR;
props.type = BACKLIGHT_RAW;
props.power = FB_BLANK_UNBLANK;
props.fb_blank = FB_BLANK_UNBLANK;
chip->bl = devm_backlight_device_register(chip->dev, "mp3309c",
chip->dev, chip,
&mp3309c_bl_ops, &props);
if (IS_ERR(chip->bl))
return dev_err_probe(chip->dev, PTR_ERR(chip->bl),
"error registering backlight device\n");
/* In PWM dimming mode, enable pwm device */
if (chip->pdata->dimming_mode == DIMMING_PWM) {
pwm_init_state(chip->pwmd, &pwmstate);
pwm_set_relative_duty_cycle(&pwmstate,
chip->pdata->default_brightness,
chip->pdata->max_brightness);
pwmstate.enabled = true;
ret = pwm_apply_might_sleep(chip->pwmd, &pwmstate);
if (ret)
return dev_err_probe(chip->dev, ret,
"error setting pwm device\n");
}
chip->pdata->status = FIRST_POWER_ON;
backlight_update_status(chip->bl);
return 0;
}
static void mp3309c_remove(struct i2c_client *client)
{
struct mp3309c_chip *chip = i2c_get_clientdata(client);
struct backlight_device *bl = chip->bl;
bl->props.power = FB_BLANK_POWERDOWN;
bl->props.brightness = 0;
backlight_update_status(chip->bl);
}
static const struct of_device_id mp3309c_match_table[] = {
{ .compatible = "mps,mp3309c", },
{ },
};
MODULE_DEVICE_TABLE(of, mp3309c_match_table);
static const struct i2c_device_id mp3309c_id[] = {
{ "mp3309c", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, mp3309c_id);
static struct i2c_driver mp3309c_i2c_driver = {
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = mp3309c_match_table,
},
.probe = mp3309c_probe,
.remove = mp3309c_remove,
.id_table = mp3309c_id,
};
module_i2c_driver(mp3309c_i2c_driver);
MODULE_DESCRIPTION("Backlight Driver for MPS MP3309C");
MODULE_AUTHOR("Flavio Suligoi <f.suligoi@asem.it>");
MODULE_LICENSE("GPL");
|