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
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
/**
 * ds2482.c - provides i2c to w1-master bridge(s)
 * Copyright (C) 2005  Ben Gardner <bgardner@wabtec.com>
 *
 * The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim).
 * It is a I2C to 1-wire bridge.
 * There are two variations: -100 and -800, which have 1 or 8 1-wire ports.
 * The complete datasheet can be obtained from MAXIM's website at:
 *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <asm/delay.h>

#include "../w1.h"
#include "../w1_int.h"

/**
 * Allow the active pullup to be disabled, default is enabled.
 *
 * Note from the DS2482 datasheet:
 * The APU bit controls whether an active pullup (controlled slew-rate
 * transistor) or a passive pullup (Rwpu resistor) will be used to drive
 * a 1-Wire line from low to high. When APU = 0, active pullup is disabled
 * (resistor mode). Active Pullup should always be selected unless there is
 * only a single slave on the 1-Wire line.
 */
static int ds2482_active_pullup = 1;
module_param_named(active_pullup, ds2482_active_pullup, int, 0644);

/**
 * The DS2482 registers - there are 3 registers that are addressed by a read
 * pointer. The read pointer is set by the last command executed.
 *
 * To read the data, issue a register read for any address
 */
#define DS2482_CMD_RESET		0xF0	/* No param */
#define DS2482_CMD_SET_READ_PTR		0xE1	/* Param: DS2482_PTR_CODE_xxx */
#define DS2482_CMD_CHANNEL_SELECT	0xC3	/* Param: Channel byte - DS2482-800 only */
#define DS2482_CMD_WRITE_CONFIG		0xD2	/* Param: Config byte */
#define DS2482_CMD_1WIRE_RESET		0xB4	/* Param: None */
#define DS2482_CMD_1WIRE_SINGLE_BIT	0x87	/* Param: Bit byte (bit7) */
#define DS2482_CMD_1WIRE_WRITE_BYTE	0xA5	/* Param: Data byte */
#define DS2482_CMD_1WIRE_READ_BYTE	0x96	/* Param: None */
/* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
#define DS2482_CMD_1WIRE_TRIPLET	0x78	/* Param: Dir byte (bit7) */

/* Values for DS2482_CMD_SET_READ_PTR */
#define DS2482_PTR_CODE_STATUS		0xF0
#define DS2482_PTR_CODE_DATA		0xE1
#define DS2482_PTR_CODE_CHANNEL		0xD2	/* DS2482-800 only */
#define DS2482_PTR_CODE_CONFIG		0xC3

/**
 * Configure Register bit definitions
 * The top 4 bits always read 0.
 * To write, the top nibble must be the 1's compl. of the low nibble.
 */
#define DS2482_REG_CFG_1WS		0x08	/* 1-wire speed */
#define DS2482_REG_CFG_SPU		0x04	/* strong pull-up */
#define DS2482_REG_CFG_PPM		0x02	/* presence pulse masking */
#define DS2482_REG_CFG_APU		0x01	/* active pull-up */


/**
 * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
 * To set the channel, write the value at the index of the channel.
 * Read and compare against the corresponding value to verify the change.
 */
static const u8 ds2482_chan_wr[8] =
	{ 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
static const u8 ds2482_chan_rd[8] =
	{ 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };


/**
 * Status Register bit definitions (read only)
 */
#define DS2482_REG_STS_DIR		0x80
#define DS2482_REG_STS_TSB		0x40
#define DS2482_REG_STS_SBR		0x20
#define DS2482_REG_STS_RST		0x10
#define DS2482_REG_STS_LL		0x08
#define DS2482_REG_STS_SD		0x04
#define DS2482_REG_STS_PPD		0x02
#define DS2482_REG_STS_1WB		0x01


static int ds2482_probe(struct i2c_client *client,
			const struct i2c_device_id *id);
static int ds2482_remove(struct i2c_client *client);


/**
 * Driver data (common to all clients)
 */
static const struct i2c_device_id ds2482_id[] = {
	{ "ds2482", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, ds2482_id);

static struct i2c_driver ds2482_driver = {
	.driver = {
		.name	= "ds2482",
	},
	.probe		= ds2482_probe,
	.remove		= ds2482_remove,
	.id_table	= ds2482_id,
};

/*
 * Client data (each client gets its own)
 */

struct ds2482_data;

struct ds2482_w1_chan {
	struct ds2482_data	*pdev;
	u8			channel;
	struct w1_bus_master	w1_bm;
};

struct ds2482_data {
	struct i2c_client	*client;
	struct mutex		access_lock;

	/* 1-wire interface(s) */
	int			w1_count;	/* 1 or 8 */
	struct ds2482_w1_chan	w1_ch[8];

	/* per-device values */
	u8			channel;
	u8			read_prt;	/* see DS2482_PTR_CODE_xxx */
	u8			reg_config;
};


/**
 * Helper to calculate values for configuration register
 * @param conf the raw config value
 * @return the value w/ complements that can be written to register
 */
static inline u8 ds2482_calculate_config(u8 conf)
{
	if (ds2482_active_pullup)
		conf |= DS2482_REG_CFG_APU;

	return conf | ((~conf & 0x0f) << 4);
}


/**
 * Sets the read pointer.
 * @param pdev		The ds2482 client pointer
 * @param read_ptr	see DS2482_PTR_CODE_xxx above
 * @return -1 on failure, 0 on success
 */
static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
{
	if (pdev->read_prt != read_ptr) {
		if (i2c_smbus_write_byte_data(pdev->client,
					      DS2482_CMD_SET_READ_PTR,
					      read_ptr) < 0)
			return -1;

		pdev->read_prt = read_ptr;
	}
	return 0;
}

/**
 * Sends a command without a parameter
 * @param pdev	The ds2482 client pointer
 * @param cmd	DS2482_CMD_RESET,
 *		DS2482_CMD_1WIRE_RESET,
 *		DS2482_CMD_1WIRE_READ_BYTE
 * @return -1 on failure, 0 on success
 */
static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
{
	if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
		return -1;

	pdev->read_prt = DS2482_PTR_CODE_STATUS;
	return 0;
}

/**
 * Sends a command with a parameter
 * @param pdev	The ds2482 client pointer
 * @param cmd	DS2482_CMD_WRITE_CONFIG,
 *		DS2482_CMD_1WIRE_SINGLE_BIT,
 *		DS2482_CMD_1WIRE_WRITE_BYTE,
 *		DS2482_CMD_1WIRE_TRIPLET
 * @param byte	The data to send
 * @return -1 on failure, 0 on success
 */
static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
				       u8 cmd, u8 byte)
{
	if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
		return -1;

	/* all cmds leave in STATUS, except CONFIG */
	pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
			 DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
	return 0;
}


/*
 * 1-Wire interface code
 */

#define DS2482_WAIT_IDLE_TIMEOUT	100

/**
 * Waits until the 1-wire interface is idle (not busy)
 *
 * @param pdev Pointer to the device structure
 * @return the last value read from status or -1 (failure)
 */
static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
{
	int temp = -1;
	int retries = 0;

	if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
		do {
			temp = i2c_smbus_read_byte(pdev->client);
		} while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
			 (++retries < DS2482_WAIT_IDLE_TIMEOUT));
	}

	if (retries >= DS2482_WAIT_IDLE_TIMEOUT)
		pr_err("%s: timeout on channel %d\n",
		       __func__, pdev->channel);

	return temp;
}

/**
 * Selects a w1 channel.
 * The 1-wire interface must be idle before calling this function.
 *
 * @param pdev		The ds2482 client pointer
 * @param channel	0-7
 * @return		-1 (failure) or 0 (success)
 */
static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
{
	if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
				      ds2482_chan_wr[channel]) < 0)
		return -1;

	pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
	pdev->channel = -1;
	if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
		pdev->channel = channel;
		return 0;
	}
	return -1;
}


/**
 * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
 *
 * @param data	The ds2482 channel pointer
 * @param bit	The level to write: 0 or non-zero
 * @return	The level read: 0 or 1
 */
static u8 ds2482_w1_touch_bit(void *data, u8 bit)
{
	struct ds2482_w1_chan *pchan = data;
	struct ds2482_data    *pdev = pchan->pdev;
	int status = -1;

	mutex_lock(&pdev->access_lock);

	/* Select the channel */
	ds2482_wait_1wire_idle(pdev);
	if (pdev->w1_count > 1)
		ds2482_set_channel(pdev, pchan->channel);

	/* Send the touch command, wait until 1WB == 0, return the status */
	if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
				  bit ? 0xFF : 0))
		status = ds2482_wait_1wire_idle(pdev);

	mutex_unlock(&pdev->access_lock);

	return (status & DS2482_REG_STS_SBR) ? 1 : 0;
}

/**
 * Performs the triplet function, which reads two bits and writes a bit.
 * The bit written is determined by the two reads:
 *   00 => dbit, 01 => 0, 10 => 1
 *
 * @param data	The ds2482 channel pointer
 * @param dbit	The direction to choose if both branches are valid
 * @return	b0=read1 b1=read2 b3=bit written
 */
static u8 ds2482_w1_triplet(void *data, u8 dbit)
{
	struct ds2482_w1_chan *pchan = data;
	struct ds2482_data    *pdev = pchan->pdev;
	int status = (3 << 5);

	mutex_lock(&pdev->access_lock);

	/* Select the channel */
	ds2482_wait_1wire_idle(pdev);
	if (pdev->w1_count > 1)
		ds2482_set_channel(pdev, pchan->channel);

	/* Send the triplet command, wait until 1WB == 0, return the status */
	if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
				  dbit ? 0xFF : 0))
		status = ds2482_wait_1wire_idle(pdev);

	mutex_unlock(&pdev->access_lock);

	/* Decode the status */
	return (status >> 5);
}

/**
 * Performs the write byte function.
 *
 * @param data	The ds2482 channel pointer
 * @param byte	The value to write
 */
static void ds2482_w1_write_byte(void *data, u8 byte)
{
	struct ds2482_w1_chan *pchan = data;
	struct ds2482_data    *pdev = pchan->pdev;

	mutex_lock(&pdev->access_lock);

	/* Select the channel */
	ds2482_wait_1wire_idle(pdev);
	if (pdev->w1_count > 1)
		ds2482_set_channel(pdev, pchan->channel);

	/* Send the write byte command */
	ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);

	mutex_unlock(&pdev->access_lock);
}

/**
 * Performs the read byte function.
 *
 * @param data	The ds2482 channel pointer
 * @return	The value read
 */
static u8 ds2482_w1_read_byte(void *data)
{
	struct ds2482_w1_chan *pchan = data;
	struct ds2482_data    *pdev = pchan->pdev;
	int result;

	mutex_lock(&pdev->access_lock);

	/* Select the channel */
	ds2482_wait_1wire_idle(pdev);
	if (pdev->w1_count > 1)
		ds2482_set_channel(pdev, pchan->channel);

	/* Send the read byte command */
	ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);

	/* Wait until 1WB == 0 */
	ds2482_wait_1wire_idle(pdev);

	/* Select the data register */
	ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);

	/* Read the data byte */
	result = i2c_smbus_read_byte(pdev->client);

	mutex_unlock(&pdev->access_lock);

	return result;
}


/**
 * Sends a reset on the 1-wire interface
 *
 * @param data	The ds2482 channel pointer
 * @return	0=Device present, 1=No device present or error
 */
static u8 ds2482_w1_reset_bus(void *data)
{
	struct ds2482_w1_chan *pchan = data;
	struct ds2482_data    *pdev = pchan->pdev;
	int err;
	u8 retval = 1;

	mutex_lock(&pdev->access_lock);

	/* Select the channel */
	ds2482_wait_1wire_idle(pdev);
	if (pdev->w1_count > 1)
		ds2482_set_channel(pdev, pchan->channel);

	/* Send the reset command */
	err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
	if (err >= 0) {
		/* Wait until the reset is complete */
		err = ds2482_wait_1wire_idle(pdev);
		retval = !(err & DS2482_REG_STS_PPD);

		/* If the chip did reset since detect, re-config it */
		if (err & DS2482_REG_STS_RST)
			ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
					     ds2482_calculate_config(0x00));
	}

	mutex_unlock(&pdev->access_lock);

	return retval;
}

static u8 ds2482_w1_set_pullup(void *data, int delay)
{
	struct ds2482_w1_chan *pchan = data;
	struct ds2482_data    *pdev = pchan->pdev;
	u8 retval = 1;

	/* if delay is non-zero activate the pullup,
	 * the strong pullup will be automatically deactivated
	 * by the master, so do not explicitly deactive it
	 */
	if (delay) {
		/* both waits are crucial, otherwise devices might not be
		 * powered long enough, causing e.g. a w1_therm sensor to
		 * provide wrong conversion results
		 */
		ds2482_wait_1wire_idle(pdev);
		/* note: it seems like both SPU and APU have to be set! */
		retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
			ds2482_calculate_config(DS2482_REG_CFG_SPU |
						DS2482_REG_CFG_APU));
		ds2482_wait_1wire_idle(pdev);
	}

	return retval;
}


static int ds2482_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	struct ds2482_data *data;
	int err = -ENODEV;
	int temp1;
	int idx;

	if (!i2c_check_functionality(client->adapter,
				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
				     I2C_FUNC_SMBUS_BYTE))
		return -ENODEV;

	if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
		err = -ENOMEM;
		goto exit;
	}

	data->client = client;
	i2c_set_clientdata(client, data);

	/* Reset the device (sets the read_ptr to status) */
	if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
		dev_warn(&client->dev, "DS2482 reset failed.\n");
		goto exit_free;
	}

	/* Sleep at least 525ns to allow the reset to complete */
	ndelay(525);

	/* Read the status byte - only reset bit and line should be set */
	temp1 = i2c_smbus_read_byte(client);
	if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
		dev_warn(&client->dev, "DS2482 reset status "
			 "0x%02X - not a DS2482\n", temp1);
		goto exit_free;
	}

	/* Detect the 8-port version */
	data->w1_count = 1;
	if (ds2482_set_channel(data, 7) == 0)
		data->w1_count = 8;

	/* Set all config items to 0 (off) */
	ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG,
		ds2482_calculate_config(0x00));

	mutex_init(&data->access_lock);

	/* Register 1-wire interface(s) */
	for (idx = 0; idx < data->w1_count; idx++) {
		data->w1_ch[idx].pdev = data;
		data->w1_ch[idx].channel = idx;

		/* Populate all the w1 bus master stuff */
		data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];
		data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;
		data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
		data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
		data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
		data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;
		data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;

		err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
		if (err) {
			data->w1_ch[idx].pdev = NULL;
			goto exit_w1_remove;
		}
	}

	return 0;

exit_w1_remove:
	for (idx = 0; idx < data->w1_count; idx++) {
		if (data->w1_ch[idx].pdev != NULL)
			w1_remove_master_device(&data->w1_ch[idx].w1_bm);
	}
exit_free:
	kfree(data);
exit:
	return err;
}

static int ds2482_remove(struct i2c_client *client)
{
	struct ds2482_data   *data = i2c_get_clientdata(client);
	int idx;

	/* Unregister the 1-wire bridge(s) */
	for (idx = 0; idx < data->w1_count; idx++) {
		if (data->w1_ch[idx].pdev != NULL)
			w1_remove_master_device(&data->w1_ch[idx].w1_bm);
	}

	/* Free the memory */
	kfree(data);
	return 0;
}

module_i2c_driver(ds2482_driver);

MODULE_PARM_DESC(active_pullup, "Active pullup (apply to all buses): " \
				"0-disable, 1-enable (default)");
MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
MODULE_DESCRIPTION("DS2482 driver");
MODULE_LICENSE("GPL");