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

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source code of linux/drivers/w1/masters/ds2482.c