1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ds2482.c - provides i2c to w1-master bridge(s)
4 * Copyright (C) 2005  Ben Gardner <bgardner@wabtec.com>
5 *
6 * The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim).
7 * It is a I2C to 1-wire bridge.
8 * There are two variations: -100 and -800, which have 1 or 8 1-wire ports.
9 * The complete datasheet can be obtained from MAXIM's website at:
10 *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382
11 */
12
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/slab.h>
16#include <linux/i2c.h>
17#include <linux/delay.h>
18
19#include <linux/w1.h>
20
21/*
22 * Allow the active pullup to be disabled, default is enabled.
23 *
24 * Note from the DS2482 datasheet:
25 * The APU bit controls whether an active pullup (controlled slew-rate
26 * transistor) or a passive pullup (Rwpu resistor) will be used to drive
27 * a 1-Wire line from low to high. When APU = 0, active pullup is disabled
28 * (resistor mode). Active Pullup should always be selected unless there is
29 * only a single slave on the 1-Wire line.
30 */
31static int ds2482_active_pullup = 1;
32module_param_named(active_pullup, ds2482_active_pullup, int, 0644);
33MODULE_PARM_DESC(active_pullup, "Active pullup (apply to all buses): " \
34				"0-disable, 1-enable (default)");
35
36/* extra configurations - e.g. 1WS */
37static int extra_config;
38module_param(extra_config, int, 0644);
39MODULE_PARM_DESC(extra_config, "Extra Configuration settings 1=APU,2=PPM,3=SPU,8=1WS");
40
41/*
42 * The DS2482 registers - there are 3 registers that are addressed by a read
43 * pointer. The read pointer is set by the last command executed.
44 *
45 * To read the data, issue a register read for any address
46 */
47#define DS2482_CMD_RESET		0xF0	/* No param */
48#define DS2482_CMD_SET_READ_PTR		0xE1	/* Param: DS2482_PTR_CODE_xxx */
49#define DS2482_CMD_CHANNEL_SELECT	0xC3	/* Param: Channel byte - DS2482-800 only */
50#define DS2482_CMD_WRITE_CONFIG		0xD2	/* Param: Config byte */
51#define DS2482_CMD_1WIRE_RESET		0xB4	/* Param: None */
52#define DS2482_CMD_1WIRE_SINGLE_BIT	0x87	/* Param: Bit byte (bit7) */
53#define DS2482_CMD_1WIRE_WRITE_BYTE	0xA5	/* Param: Data byte */
54#define DS2482_CMD_1WIRE_READ_BYTE	0x96	/* Param: None */
55/* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
56#define DS2482_CMD_1WIRE_TRIPLET	0x78	/* Param: Dir byte (bit7) */
57
58/* Values for DS2482_CMD_SET_READ_PTR */
59#define DS2482_PTR_CODE_STATUS		0xF0
60#define DS2482_PTR_CODE_DATA		0xE1
61#define DS2482_PTR_CODE_CHANNEL		0xD2	/* DS2482-800 only */
62#define DS2482_PTR_CODE_CONFIG		0xC3
63
64/*
65 * Configure Register bit definitions
66 * The top 4 bits always read 0.
67 * To write, the top nibble must be the 1's compl. of the low nibble.
68 */
69#define DS2482_REG_CFG_1WS		0x08	/* 1-wire speed */
70#define DS2482_REG_CFG_SPU		0x04	/* strong pull-up */
71#define DS2482_REG_CFG_PPM		0x02	/* presence pulse masking */
72#define DS2482_REG_CFG_APU		0x01	/* active pull-up */
73
74
75/*
76 * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
77 * To set the channel, write the value at the index of the channel.
78 * Read and compare against the corresponding value to verify the change.
79 */
80static const u8 ds2482_chan_wr[8] = { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
81static const u8 ds2482_chan_rd[8] = { 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };
82
83
84/*
85 * Status Register bit definitions (read only)
86 */
87#define DS2482_REG_STS_DIR		0x80
88#define DS2482_REG_STS_TSB		0x40
89#define DS2482_REG_STS_SBR		0x20
90#define DS2482_REG_STS_RST		0x10
91#define DS2482_REG_STS_LL		0x08
92#define DS2482_REG_STS_SD		0x04
93#define DS2482_REG_STS_PPD		0x02
94#define DS2482_REG_STS_1WB		0x01
95
96/*
97 * Client data (each client gets its own)
98 */
99
100struct ds2482_data;
101
102struct ds2482_w1_chan {
103	struct ds2482_data	*pdev;
104	u8			channel;
105	struct w1_bus_master	w1_bm;
106};
107
108struct ds2482_data {
109	struct i2c_client	*client;
110	struct mutex		access_lock;
111
112	/* 1-wire interface(s) */
113	int			w1_count;	/* 1 or 8 */
114	struct ds2482_w1_chan	w1_ch[8];
115
116	/* per-device values */
117	u8			channel;
118	u8			read_prt;	/* see DS2482_PTR_CODE_xxx */
119	u8			reg_config;
120};
121
122
123/**
124 * ds2482_calculate_config - Helper to calculate values for configuration register
125 * @conf: the raw config value
126 * Return: the value w/ complements that can be written to register
127 */
128static inline u8 ds2482_calculate_config(u8 conf)
129{
130	conf |= extra_config;
131
132	if (ds2482_active_pullup)
133		conf |= DS2482_REG_CFG_APU;
134
135	return conf | ((~conf & 0x0f) << 4);
136}
137
138
139/**
140 * ds2482_select_register - Sets the read pointer.
141 * @pdev:		The ds2482 client pointer
142 * @read_ptr:	see DS2482_PTR_CODE_xxx above
143 * Return: -1 on failure, 0 on success
144 */
145static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
146{
147	if (pdev->read_prt != read_ptr) {
148		if (i2c_smbus_write_byte_data(pdev->client,
149					      DS2482_CMD_SET_READ_PTR,
150					      read_ptr) < 0)
151			return -1;
152
153		pdev->read_prt = read_ptr;
154	}
155	return 0;
156}
157
158/**
159 * ds2482_send_cmd - Sends a command without a parameter
160 * @pdev:	The ds2482 client pointer
161 * @cmd:	DS2482_CMD_RESET,
162 *		DS2482_CMD_1WIRE_RESET,
163 *		DS2482_CMD_1WIRE_READ_BYTE
164 * Return: -1 on failure, 0 on success
165 */
166static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
167{
168	if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
169		return -1;
170
171	pdev->read_prt = DS2482_PTR_CODE_STATUS;
172	return 0;
173}
174
175/**
176 * ds2482_send_cmd_data - Sends a command with a parameter
177 * @pdev:	The ds2482 client pointer
178 * @cmd:	DS2482_CMD_WRITE_CONFIG,
179 *		DS2482_CMD_1WIRE_SINGLE_BIT,
180 *		DS2482_CMD_1WIRE_WRITE_BYTE,
181 *		DS2482_CMD_1WIRE_TRIPLET
182 * @byte:	The data to send
183 * Return: -1 on failure, 0 on success
184 */
185static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
186				       u8 cmd, u8 byte)
187{
188	if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
189		return -1;
190
191	/* all cmds leave in STATUS, except CONFIG */
192	pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
193			 DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
194	return 0;
195}
196
197
198/*
199 * 1-Wire interface code
200 */
201
202#define DS2482_WAIT_IDLE_TIMEOUT	100
203
204/**
205 * ds2482_wait_1wire_idle - Waits until the 1-wire interface is idle (not busy)
206 *
207 * @pdev: Pointer to the device structure
208 * Return: the last value read from status or -1 (failure)
209 */
210static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
211{
212	int temp = -1;
213	int retries = 0;
214
215	if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
216		do {
217			temp = i2c_smbus_read_byte(pdev->client);
218		} while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
219			 (++retries < DS2482_WAIT_IDLE_TIMEOUT));
220	}
221
222	if (retries >= DS2482_WAIT_IDLE_TIMEOUT)
223		pr_err("%s: timeout on channel %d\n",
224		       __func__, pdev->channel);
225
226	return temp;
227}
228
229/**
230 * ds2482_set_channel - Selects a w1 channel.
231 * The 1-wire interface must be idle before calling this function.
232 *
233 * @pdev:		The ds2482 client pointer
234 * @channel:		0-7
235 * Return:		-1 (failure) or 0 (success)
236 */
237static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
238{
239	if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
240				      ds2482_chan_wr[channel]) < 0)
241		return -1;
242
243	pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
244	pdev->channel = -1;
245	if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
246		pdev->channel = channel;
247		return 0;
248	}
249	return -1;
250}
251
252
253/**
254 * ds2482_w1_touch_bit - Performs the touch-bit function, which writes a 0 or 1 and reads the level.
255 *
256 * @data:	The ds2482 channel pointer
257 * @bit:	The level to write: 0 or non-zero
258 * Return:	The level read: 0 or 1
259 */
260static u8 ds2482_w1_touch_bit(void *data, u8 bit)
261{
262	struct ds2482_w1_chan *pchan = data;
263	struct ds2482_data    *pdev = pchan->pdev;
264	int status = -1;
265
266	mutex_lock(&pdev->access_lock);
267
268	/* Select the channel */
269	ds2482_wait_1wire_idle(pdev);
270	if (pdev->w1_count > 1)
271		ds2482_set_channel(pdev, pchan->channel);
272
273	/* Send the touch command, wait until 1WB == 0, return the status */
274	if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
275				  bit ? 0xFF : 0))
276		status = ds2482_wait_1wire_idle(pdev);
277
278	mutex_unlock(&pdev->access_lock);
279
280	return (status & DS2482_REG_STS_SBR) ? 1 : 0;
281}
282
283/**
284 * ds2482_w1_triplet - Performs the triplet function, which reads two bits and writes a bit.
285 * The bit written is determined by the two reads:
286 *   00 => dbit, 01 => 0, 10 => 1
287 *
288 * @data:	The ds2482 channel pointer
289 * @dbit:	The direction to choose if both branches are valid
290 * Return:	b0=read1 b1=read2 b3=bit written
291 */
292static u8 ds2482_w1_triplet(void *data, u8 dbit)
293{
294	struct ds2482_w1_chan *pchan = data;
295	struct ds2482_data    *pdev = pchan->pdev;
296	int status = (3 << 5);
297
298	mutex_lock(&pdev->access_lock);
299
300	/* Select the channel */
301	ds2482_wait_1wire_idle(pdev);
302	if (pdev->w1_count > 1)
303		ds2482_set_channel(pdev, pchan->channel);
304
305	/* Send the triplet command, wait until 1WB == 0, return the status */
306	if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
307				  dbit ? 0xFF : 0))
308		status = ds2482_wait_1wire_idle(pdev);
309
310	mutex_unlock(&pdev->access_lock);
311
312	/* Decode the status */
313	return (status >> 5);
314}
315
316/**
317 * ds2482_w1_write_byte - Performs the write byte function.
318 *
319 * @data:	The ds2482 channel pointer
320 * @byte:	The value to write
321 */
322static void ds2482_w1_write_byte(void *data, u8 byte)
323{
324	struct ds2482_w1_chan *pchan = data;
325	struct ds2482_data    *pdev = pchan->pdev;
326
327	mutex_lock(&pdev->access_lock);
328
329	/* Select the channel */
330	ds2482_wait_1wire_idle(pdev);
331	if (pdev->w1_count > 1)
332		ds2482_set_channel(pdev, pchan->channel);
333
334	/* Send the write byte command */
335	ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
336
337	mutex_unlock(&pdev->access_lock);
338}
339
340/**
341 * ds2482_w1_read_byte - Performs the read byte function.
342 *
343 * @data:	The ds2482 channel pointer
344 * Return:	The value read
345 */
346static u8 ds2482_w1_read_byte(void *data)
347{
348	struct ds2482_w1_chan *pchan = data;
349	struct ds2482_data    *pdev = pchan->pdev;
350	int result;
351
352	mutex_lock(&pdev->access_lock);
353
354	/* Select the channel */
355	ds2482_wait_1wire_idle(pdev);
356	if (pdev->w1_count > 1)
357		ds2482_set_channel(pdev, pchan->channel);
358
359	/* Send the read byte command */
360	ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
361
362	/* Wait until 1WB == 0 */
363	ds2482_wait_1wire_idle(pdev);
364
365	/* Select the data register */
366	ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
367
368	/* Read the data byte */
369	result = i2c_smbus_read_byte(pdev->client);
370
371	mutex_unlock(&pdev->access_lock);
372
373	return result;
374}
375
376
377/**
378 * ds2482_w1_reset_bus - Sends a reset on the 1-wire interface
379 *
380 * @data:	The ds2482 channel pointer
381 * Return:	0=Device present, 1=No device present or error
382 */
383static u8 ds2482_w1_reset_bus(void *data)
384{
385	struct ds2482_w1_chan *pchan = data;
386	struct ds2482_data    *pdev = pchan->pdev;
387	int err;
388	u8 retval = 1;
389
390	mutex_lock(&pdev->access_lock);
391
392	/* Select the channel */
393	ds2482_wait_1wire_idle(pdev);
394	if (pdev->w1_count > 1)
395		ds2482_set_channel(pdev, pchan->channel);
396
397	/* Send the reset command */
398	err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
399	if (err >= 0) {
400		/* Wait until the reset is complete */
401		err = ds2482_wait_1wire_idle(pdev);
402		retval = !(err & DS2482_REG_STS_PPD);
403
404		/* If the chip did reset since detect, re-config it */
405		if (err & DS2482_REG_STS_RST)
406			ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
407					     ds2482_calculate_config(0x00));
408	}
409
410	mutex_unlock(&pdev->access_lock);
411
412	return retval;
413}
414
415static u8 ds2482_w1_set_pullup(void *data, int delay)
416{
417	struct ds2482_w1_chan *pchan = data;
418	struct ds2482_data    *pdev = pchan->pdev;
419	u8 retval = 1;
420
421	/* if delay is non-zero activate the pullup,
422	 * the strong pullup will be automatically deactivated
423	 * by the master, so do not explicitly deactive it
424	 */
425	if (delay) {
426		/* both waits are crucial, otherwise devices might not be
427		 * powered long enough, causing e.g. a w1_therm sensor to
428		 * provide wrong conversion results
429		 */
430		ds2482_wait_1wire_idle(pdev);
431		/* note: it seems like both SPU and APU have to be set! */
432		retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
433			ds2482_calculate_config(DS2482_REG_CFG_SPU |
434						DS2482_REG_CFG_APU));
435		ds2482_wait_1wire_idle(pdev);
436	}
437
438	return retval;
439}
440
441
442static int ds2482_probe(struct i2c_client *client)
443{
444	struct ds2482_data *data;
445	int err = -ENODEV;
446	int temp1;
447	int idx;
448
449	if (!i2c_check_functionality(client->adapter,
450				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
451				     I2C_FUNC_SMBUS_BYTE))
452		return -ENODEV;
453
454	data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL);
455	if (!data) {
456		err = -ENOMEM;
457		goto exit;
458	}
459
460	data->client = client;
461	i2c_set_clientdata(client, data);
462
463	/* Reset the device (sets the read_ptr to status) */
464	if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
465		dev_warn(&client->dev, "DS2482 reset failed.\n");
466		goto exit_free;
467	}
468
469	/* Sleep at least 525ns to allow the reset to complete */
470	ndelay(525);
471
472	/* Read the status byte - only reset bit and line should be set */
473	temp1 = i2c_smbus_read_byte(client);
474	if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
475		dev_warn(&client->dev, "DS2482 reset status "
476			 "0x%02X - not a DS2482\n", temp1);
477		goto exit_free;
478	}
479
480	/* Detect the 8-port version */
481	data->w1_count = 1;
482	if (ds2482_set_channel(data, 7) == 0)
483		data->w1_count = 8;
484
485	/* Set all config items to 0 (off) */
486	ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG,
487		ds2482_calculate_config(0x00));
488
489	mutex_init(&data->access_lock);
490
491	/* Register 1-wire interface(s) */
492	for (idx = 0; idx < data->w1_count; idx++) {
493		data->w1_ch[idx].pdev = data;
494		data->w1_ch[idx].channel = idx;
495
496		/* Populate all the w1 bus master stuff */
497		data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];
498		data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;
499		data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
500		data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
501		data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
502		data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;
503		data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;
504
505		err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
506		if (err) {
507			data->w1_ch[idx].pdev = NULL;
508			goto exit_w1_remove;
509		}
510	}
511
512	return 0;
513
514exit_w1_remove:
515	for (idx = 0; idx < data->w1_count; idx++) {
516		if (data->w1_ch[idx].pdev != NULL)
517			w1_remove_master_device(&data->w1_ch[idx].w1_bm);
518	}
519exit_free:
520	kfree(data);
521exit:
522	return err;
523}
524
525static void ds2482_remove(struct i2c_client *client)
526{
527	struct ds2482_data   *data = i2c_get_clientdata(client);
528	int idx;
529
530	/* Unregister the 1-wire bridge(s) */
531	for (idx = 0; idx < data->w1_count; idx++) {
532		if (data->w1_ch[idx].pdev != NULL)
533			w1_remove_master_device(&data->w1_ch[idx].w1_bm);
534	}
535
536	/* Free the memory */
537	kfree(data);
538}
539
540/*
541 * Driver data (common to all clients)
542 */
543static const struct i2c_device_id ds2482_id[] = {
544	{ "ds2482", 0 },
545	{ "ds2484", 0 },
546	{ }
547};
548MODULE_DEVICE_TABLE(i2c, ds2482_id);
549
550static struct i2c_driver ds2482_driver = {
551	.driver = {
552		.name	= "ds2482",
553	},
554	.probe		= ds2482_probe,
555	.remove		= ds2482_remove,
556	.id_table	= ds2482_id,
557};
558module_i2c_driver(ds2482_driver);
559
560MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
561MODULE_DESCRIPTION("DS2482 driver");
562
563MODULE_LICENSE("GPL");
564