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 */
31 static int ds2482_active_pullup = 1;
32 module_param_named(active_pullup, ds2482_active_pullup, int, 0644);
33 MODULE_PARM_DESC(active_pullup, "Active pullup (apply to all buses): " \
34 "0-disable, 1-enable (default)");
35
36 /* extra configurations - e.g. 1WS */
37 static int extra_config;
38 module_param(extra_config, int, 0644);
39 MODULE_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 */
80 static const u8 ds2482_chan_wr[8] = { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
81 static 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
100 struct ds2482_data;
101
102 struct ds2482_w1_chan {
103 struct ds2482_data *pdev;
104 u8 channel;
105 struct w1_bus_master w1_bm;
106 };
107
108 struct 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 */
ds2482_calculate_config(u8 conf)128 static 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 */
ds2482_select_register(struct ds2482_data * pdev,u8 read_ptr)145 static 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 */
ds2482_send_cmd(struct ds2482_data * pdev,u8 cmd)166 static 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 */
ds2482_send_cmd_data(struct ds2482_data * pdev,u8 cmd,u8 byte)185 static 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 */
ds2482_wait_1wire_idle(struct ds2482_data * pdev)210 static 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 */
ds2482_set_channel(struct ds2482_data * pdev,u8 channel)237 static 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 */
ds2482_w1_touch_bit(void * data,u8 bit)260 static 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 */
ds2482_w1_triplet(void * data,u8 dbit)292 static 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 */
ds2482_w1_write_byte(void * data,u8 byte)322 static 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 */
ds2482_w1_read_byte(void * data)346 static 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 */
ds2482_w1_reset_bus(void * data)383 static 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
ds2482_w1_set_pullup(void * data,int delay)415 static 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
ds2482_probe(struct i2c_client * client)442 static 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
514 exit_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 }
519 exit_free:
520 kfree(data);
521 exit:
522 return err;
523 }
524
ds2482_remove(struct i2c_client * client)525 static 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 */
543 static const struct i2c_device_id ds2482_id[] = {
544 { "ds2482", 0 },
545 { "ds2484", 0 },
546 { }
547 };
548 MODULE_DEVICE_TABLE(i2c, ds2482_id);
549
550 static 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 };
558 module_i2c_driver(ds2482_driver);
559
560 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
561 MODULE_DESCRIPTION("DS2482 driver");
562
563 MODULE_LICENSE("GPL");
564