Linux preempt-rt

Check our new training course

Real-Time Linux with PREEMPT_RT

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  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
/*
 * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
 *
 * Copyright 2016 ArcticSand, Inc.
 * Author : Brian Dodge <bdodge@arcticsand.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/backlight.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/slab.h>

enum arcxcnn_chip_id {
	ARC2C0608
};

/**
 * struct arcxcnn_platform_data
 * @name		: Backlight driver name (NULL will use default)
 * @initial_brightness	: initial value of backlight brightness
 * @leden		: initial LED string enables, upper bit is global on/off
 * @led_config_0	: fading speed (period between intensity steps)
 * @led_config_1	: misc settings, see datasheet
 * @dim_freq		: pwm dimming frequency if in pwm mode
 * @comp_config		: misc config, see datasheet
 * @filter_config	: RC/PWM filter config, see datasheet
 * @trim_config		: full scale current trim, see datasheet
 */
struct arcxcnn_platform_data {
	const char *name;
	u16 initial_brightness;
	u8	leden;
	u8	led_config_0;
	u8	led_config_1;
	u8	dim_freq;
	u8	comp_config;
	u8	filter_config;
	u8	trim_config;
};

#define ARCXCNN_CMD		0x00	/* Command Register */
#define ARCXCNN_CMD_STDBY	0x80	/*   I2C Standby */
#define ARCXCNN_CMD_RESET	0x40	/*   Reset */
#define ARCXCNN_CMD_BOOST	0x10	/*   Boost */
#define ARCXCNN_CMD_OVP_MASK	0x0C	/*   --- Over Voltage Threshold */
#define ARCXCNN_CMD_OVP_XXV	0x0C	/*   <rsvrd> Over Voltage Threshold */
#define ARCXCNN_CMD_OVP_20V	0x08	/*   20v Over Voltage Threshold */
#define ARCXCNN_CMD_OVP_24V	0x04	/*   24v Over Voltage Threshold */
#define ARCXCNN_CMD_OVP_31V	0x00	/*   31.4v Over Voltage Threshold */
#define ARCXCNN_CMD_EXT_COMP	0x01	/*   part (0) or full (1) ext. comp */

#define ARCXCNN_CONFIG		0x01	/* Configuration */
#define ARCXCNN_STATUS1		0x02	/* Status 1 */
#define ARCXCNN_STATUS2		0x03	/* Status 2 */
#define ARCXCNN_FADECTRL	0x04	/* Fading Control */
#define ARCXCNN_ILED_CONFIG	0x05	/* ILED Configuration */
#define ARCXCNN_ILED_DIM_PWM	0x00	/*   config dim mode pwm */
#define ARCXCNN_ILED_DIM_INT	0x04	/*   config dim mode internal */
#define ARCXCNN_LEDEN		0x06	/* LED Enable Register */
#define ARCXCNN_LEDEN_ISETEXT	0x80	/*   Full-scale current set extern */
#define ARCXCNN_LEDEN_MASK	0x3F	/*   LED string enables mask */
#define ARCXCNN_LEDEN_BITS	0x06	/*   Bits of LED string enables */
#define ARCXCNN_LEDEN_LED1	0x01
#define ARCXCNN_LEDEN_LED2	0x02
#define ARCXCNN_LEDEN_LED3	0x04
#define ARCXCNN_LEDEN_LED4	0x08
#define ARCXCNN_LEDEN_LED5	0x10
#define ARCXCNN_LEDEN_LED6	0x20

#define ARCXCNN_WLED_ISET_LSB	0x07	/* LED ISET LSB (in upper nibble) */
#define ARCXCNN_WLED_ISET_LSB_SHIFT 0x04  /* ISET LSB Left Shift */
#define ARCXCNN_WLED_ISET_MSB	0x08	/* LED ISET MSB (8 bits) */

#define ARCXCNN_DIMFREQ		0x09
#define ARCXCNN_COMP_CONFIG	0x0A
#define ARCXCNN_FILT_CONFIG	0x0B
#define ARCXCNN_IMAXTUNE	0x0C
#define ARCXCNN_ID_MSB		0x1E
#define ARCXCNN_ID_LSB		0x1F

#define MAX_BRIGHTNESS		4095
#define INIT_BRIGHT		60

struct arcxcnn {
	struct i2c_client *client;
	struct backlight_device *bl;
	struct device *dev;
	struct arcxcnn_platform_data *pdata;
};

static int arcxcnn_update_field(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
{
	int ret;
	u8 tmp;

	ret = i2c_smbus_read_byte_data(lp->client, reg);
	if (ret < 0) {
		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
		return ret;
	}

	tmp = (u8)ret;
	tmp &= ~mask;
	tmp |= data & mask;

	return i2c_smbus_write_byte_data(lp->client, reg, tmp);
}

static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
{
	int ret;
	u8 val;

	/* lower nibble of brightness goes in upper nibble of LSB register */
	val = (brightness & 0xF) << ARCXCNN_WLED_ISET_LSB_SHIFT;
	ret = i2c_smbus_write_byte_data(lp->client,
		ARCXCNN_WLED_ISET_LSB, val);
	if (ret < 0)
		return ret;

	/* remaining 8 bits of brightness go in MSB register */
	val = (brightness >> 4);
	return i2c_smbus_write_byte_data(lp->client,
		ARCXCNN_WLED_ISET_MSB, val);
}

static int arcxcnn_bl_update_status(struct backlight_device *bl)
{
	struct arcxcnn *lp = bl_get_data(bl);
	u32 brightness = bl->props.brightness;
	int ret;

	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
		brightness = 0;

	ret = arcxcnn_set_brightness(lp, brightness);
	if (ret)
		return ret;

	/* set power-on/off/save modes */
	return arcxcnn_update_field(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY,
		(bl->props.power == 0) ? 0 : ARCXCNN_CMD_STDBY);
}

static const struct backlight_ops arcxcnn_bl_ops = {
	.options = BL_CORE_SUSPENDRESUME,
	.update_status = arcxcnn_bl_update_status,
};

static int arcxcnn_backlight_register(struct arcxcnn *lp)
{
	struct backlight_properties *props;
	const char *name = lp->pdata->name ? : "arctic_bl";

	props = devm_kzalloc(lp->dev, sizeof(*props), GFP_KERNEL);
	if (!props)
		return -ENOMEM;

	props->type = BACKLIGHT_PLATFORM;
	props->max_brightness = MAX_BRIGHTNESS;

	if (lp->pdata->initial_brightness > props->max_brightness)
		lp->pdata->initial_brightness = props->max_brightness;

	props->brightness = lp->pdata->initial_brightness;

	lp->bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
				       &arcxcnn_bl_ops, props);
	return PTR_ERR_OR_ZERO(lp->bl);
}

static void arcxcnn_parse_dt(struct arcxcnn *lp)
{
	struct device *dev = lp->dev;
	struct device_node *node = dev->of_node;
	u32 prog_val, num_entry, entry, sources[ARCXCNN_LEDEN_BITS];
	int ret;

	/* device tree entry isn't required, defaults are OK */
	if (!node)
		return;

	ret = of_property_read_string(node, "label", &lp->pdata->name);
	if (ret < 0)
		lp->pdata->name = NULL;

	ret = of_property_read_u32(node, "default-brightness", &prog_val);
	if (ret == 0)
		lp->pdata->initial_brightness = prog_val;

	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
	if (ret == 0)
		lp->pdata->led_config_0 = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
	if (ret == 0)
		lp->pdata->led_config_1 = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
	if (ret == 0)
		lp->pdata->dim_freq = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
	if (ret == 0)
		lp->pdata->comp_config = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
	if (ret == 0)
		lp->pdata->filter_config = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
	if (ret == 0)
		lp->pdata->trim_config = (u8)prog_val;

	ret = of_property_count_u32_elems(node, "led-sources");
	if (ret < 0) {
		lp->pdata->leden = ARCXCNN_LEDEN_MASK; /* all on is default */
	} else {
		num_entry = ret;
		if (num_entry > ARCXCNN_LEDEN_BITS)
			num_entry = ARCXCNN_LEDEN_BITS;

		ret = of_property_read_u32_array(node, "led-sources", sources,
					num_entry);
		if (ret < 0) {
			dev_err(dev, "led-sources node is invalid.\n");
			return;
		}

		lp->pdata->leden = 0;

		/* for each enable in source, set bit in led enable */
		for (entry = 0; entry < num_entry; entry++) {
			u8 onbit = 1 << sources[entry];

			lp->pdata->leden |= onbit;
		}
	}
}

static int arcxcnn_probe(struct i2c_client *cl, const struct i2c_device_id *id)
{
	struct arcxcnn *lp;
	int ret;

	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
		return -EIO;

	lp = devm_kzalloc(&cl->dev, sizeof(*lp), GFP_KERNEL);
	if (!lp)
		return -ENOMEM;

	lp->client = cl;
	lp->dev = &cl->dev;
	lp->pdata = dev_get_platdata(&cl->dev);

	/* reset the device */
	ret = i2c_smbus_write_byte_data(lp->client,
		ARCXCNN_CMD, ARCXCNN_CMD_RESET);
	if (ret)
		goto probe_err;

	if (!lp->pdata) {
		lp->pdata = devm_kzalloc(lp->dev,
				sizeof(*lp->pdata), GFP_KERNEL);
		if (!lp->pdata)
			return -ENOMEM;

		/* Setup defaults based on power-on defaults */
		lp->pdata->name = NULL;
		lp->pdata->initial_brightness = INIT_BRIGHT;
		lp->pdata->leden = ARCXCNN_LEDEN_MASK;

		lp->pdata->led_config_0 = i2c_smbus_read_byte_data(
			lp->client, ARCXCNN_FADECTRL);

		lp->pdata->led_config_1 = i2c_smbus_read_byte_data(
			lp->client, ARCXCNN_ILED_CONFIG);
		/* insure dim mode is not default pwm */
		lp->pdata->led_config_1 |= ARCXCNN_ILED_DIM_INT;

		lp->pdata->dim_freq = i2c_smbus_read_byte_data(
			lp->client, ARCXCNN_DIMFREQ);

		lp->pdata->comp_config = i2c_smbus_read_byte_data(
			lp->client, ARCXCNN_COMP_CONFIG);

		lp->pdata->filter_config = i2c_smbus_read_byte_data(
			lp->client, ARCXCNN_FILT_CONFIG);

		lp->pdata->trim_config = i2c_smbus_read_byte_data(
			lp->client, ARCXCNN_IMAXTUNE);

		if (IS_ENABLED(CONFIG_OF))
			arcxcnn_parse_dt(lp);
	}

	i2c_set_clientdata(cl, lp);

	/* constrain settings to what is possible */
	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
		lp->pdata->initial_brightness = MAX_BRIGHTNESS;

	/* set initial brightness */
	ret = arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
	if (ret)
		goto probe_err;

	/* set other register values directly */
	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FADECTRL,
		lp->pdata->led_config_0);
	if (ret)
		goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_ILED_CONFIG,
		lp->pdata->led_config_1);
	if (ret)
		goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_DIMFREQ,
		lp->pdata->dim_freq);
	if (ret)
		goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_COMP_CONFIG,
		lp->pdata->comp_config);
	if (ret)
		goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FILT_CONFIG,
		lp->pdata->filter_config);
	if (ret)
		goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_IMAXTUNE,
		lp->pdata->trim_config);
	if (ret)
		goto probe_err;

	/* set initial LED Enables */
	arcxcnn_update_field(lp, ARCXCNN_LEDEN,
		ARCXCNN_LEDEN_MASK, lp->pdata->leden);

	ret = arcxcnn_backlight_register(lp);
	if (ret)
		goto probe_register_err;

	backlight_update_status(lp->bl);

	return 0;

probe_register_err:
	dev_err(lp->dev,
		"failed to register backlight.\n");

probe_err:
	dev_err(lp->dev,
		"failure ret: %d\n", ret);
	return ret;
}

static int arcxcnn_remove(struct i2c_client *cl)
{
	struct arcxcnn *lp = i2c_get_clientdata(cl);

	/* disable all strings (ignore errors) */
	i2c_smbus_write_byte_data(lp->client,
		ARCXCNN_LEDEN, 0x00);
	/* reset the device (ignore errors) */
	i2c_smbus_write_byte_data(lp->client,
		ARCXCNN_CMD, ARCXCNN_CMD_RESET);

	lp->bl->props.brightness = 0;

	backlight_update_status(lp->bl);

	return 0;
}

static const struct of_device_id arcxcnn_dt_ids[] = {
	{ .compatible = "arc,arc2c0608" },
	{ }
};
MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);

static const struct i2c_device_id arcxcnn_ids[] = {
	{"arc2c0608", ARC2C0608},
	{ }
};
MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);

static struct i2c_driver arcxcnn_driver = {
	.driver = {
		.name = "arcxcnn_bl",
		.of_match_table = of_match_ptr(arcxcnn_dt_ids),
	},
	.probe = arcxcnn_probe,
	.remove = arcxcnn_remove,
	.id_table = arcxcnn_ids,
};
module_i2c_driver(arcxcnn_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Brian Dodge <bdodge@arcticsand.com>");
MODULE_DESCRIPTION("ARCXCNN Backlight driver");