1/**
2 * ds2482.c - provides i2c to w1-master bridge(s)
3 * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
4 *
5 * The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim).
6 * It is a I2C to 1-wire bridge.
7 * There are two variations: -100 and -800, which have 1 or 8 1-wire ports.
8 * The complete datasheet can be obtained from MAXIM's website at:
9 * http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; version 2 of the License.
14 */
15
16#include <linux/module.h>
17#include <linux/init.h>
18#include <linux/slab.h>
19#include <linux/i2c.h>
20#include <linux/delay.h>
21#include <asm/delay.h>
22
23#include <linux/w1.h>
24
25/**
26 * Allow the active pullup to be disabled, default is enabled.
27 *
28 * Note from the DS2482 datasheet:
29 * The APU bit controls whether an active pullup (controlled slew-rate
30 * transistor) or a passive pullup (Rwpu resistor) will be used to drive
31 * a 1-Wire line from low to high. When APU = 0, active pullup is disabled
32 * (resistor mode). Active Pullup should always be selected unless there is
33 * only a single slave on the 1-Wire line.
34 */
35static int ds2482_active_pullup = 1;
36module_param_named(active_pullup, ds2482_active_pullup, int, 0644);
37MODULE_PARM_DESC(active_pullup, "Active pullup (apply to all buses): " \
38 "0-disable, 1-enable (default)");
39
40/**
41 * The DS2482 registers - there are 3 registers that are addressed by a read
42 * pointer. The read pointer is set by the last command executed.
43 *
44 * To read the data, issue a register read for any address
45 */
46#define DS2482_CMD_RESET 0xF0 /* No param */
47#define DS2482_CMD_SET_READ_PTR 0xE1 /* Param: DS2482_PTR_CODE_xxx */
48#define DS2482_CMD_CHANNEL_SELECT 0xC3 /* Param: Channel byte - DS2482-800 only */
49#define DS2482_CMD_WRITE_CONFIG 0xD2 /* Param: Config byte */
50#define DS2482_CMD_1WIRE_RESET 0xB4 /* Param: None */
51#define DS2482_CMD_1WIRE_SINGLE_BIT 0x87 /* Param: Bit byte (bit7) */
52#define DS2482_CMD_1WIRE_WRITE_BYTE 0xA5 /* Param: Data byte */
53#define DS2482_CMD_1WIRE_READ_BYTE 0x96 /* Param: None */
54/* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
55#define DS2482_CMD_1WIRE_TRIPLET 0x78 /* Param: Dir byte (bit7) */
56
57/* Values for DS2482_CMD_SET_READ_PTR */
58#define DS2482_PTR_CODE_STATUS 0xF0
59#define DS2482_PTR_CODE_DATA 0xE1
60#define DS2482_PTR_CODE_CHANNEL 0xD2 /* DS2482-800 only */
61#define DS2482_PTR_CODE_CONFIG 0xC3
62
63/**
64 * Configure Register bit definitions
65 * The top 4 bits always read 0.
66 * To write, the top nibble must be the 1's compl. of the low nibble.
67 */
68#define DS2482_REG_CFG_1WS 0x08 /* 1-wire speed */
69#define DS2482_REG_CFG_SPU 0x04 /* strong pull-up */
70#define DS2482_REG_CFG_PPM 0x02 /* presence pulse masking */
71#define DS2482_REG_CFG_APU 0x01 /* active pull-up */
72
73/* extra configurations - e.g. 1WS */
74static int extra_config;
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] =
82 { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
83static const u8 ds2482_chan_rd[8] =
84 { 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };
85
86
87/**
88 * Status Register bit definitions (read only)
89 */
90#define DS2482_REG_STS_DIR 0x80
91#define DS2482_REG_STS_TSB 0x40
92#define DS2482_REG_STS_SBR 0x20
93#define DS2482_REG_STS_RST 0x10
94#define DS2482_REG_STS_LL 0x08
95#define DS2482_REG_STS_SD 0x04
96#define DS2482_REG_STS_PPD 0x02
97#define DS2482_REG_STS_1WB 0x01
98
99/*
100 * Client data (each client gets its own)
101 */
102
103struct ds2482_data;
104
105struct ds2482_w1_chan {
106 struct ds2482_data *pdev;
107 u8 channel;
108 struct w1_bus_master w1_bm;
109};
110
111struct ds2482_data {
112 struct i2c_client *client;
113 struct mutex access_lock;
114
115 /* 1-wire interface(s) */
116 int w1_count; /* 1 or 8 */
117 struct ds2482_w1_chan w1_ch[8];
118
119 /* per-device values */
120 u8 channel;
121 u8 read_prt; /* see DS2482_PTR_CODE_xxx */
122 u8 reg_config;
123};
124
125
126/**
127 * Helper to calculate values for configuration register
128 * @param conf the raw config value
129 * @return the value w/ complements that can be written to register
130 */
131static inline u8 ds2482_calculate_config(u8 conf)
132{
133 if (ds2482_active_pullup)
134 conf |= DS2482_REG_CFG_APU;
135
136 return conf | ((~conf & 0x0f) << 4);
137}
138
139
140/**
141 * Sets the read pointer.
142 * @param pdev The ds2482 client pointer
143 * @param 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(pdev->client,
150 DS2482_CMD_SET_READ_PTR,
151 read_ptr) < 0)
152 return -1;
153
154 pdev->read_prt = read_ptr;
155 }
156 return 0;
157}
158
159/**
160 * Sends a command without a parameter
161 * @param pdev The ds2482 client pointer
162 * @param 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(pdev->client, cmd) < 0)
170 return -1;
171
172 pdev->read_prt = DS2482_PTR_CODE_STATUS;
173 return 0;
174}
175
176/**
177 * Sends a command with a parameter
178 * @param pdev The ds2482 client pointer
179 * @param cmd DS2482_CMD_WRITE_CONFIG,
180 * DS2482_CMD_1WIRE_SINGLE_BIT,
181 * DS2482_CMD_1WIRE_WRITE_BYTE,
182 * DS2482_CMD_1WIRE_TRIPLET
183 * @param 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(pdev->client, cmd, 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 * Waits until the 1-wire interface is idle (not busy)
207 *
208 * @param 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(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 * Selects a w1 channel.
232 * The 1-wire interface must be idle before calling this function.
233 *
234 * @param pdev The ds2482 client pointer
235 * @param 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(pdev->client, DS2482_CMD_CHANNEL_SELECT,
241 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(pdev->client) == ds2482_chan_rd[channel]) {
247 pdev->channel = channel;
248 return 0;
249 }
250 return -1;
251}
252
253
254/**
255 * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
256 *
257 * @param data The ds2482 channel pointer
258 * @param 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, 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 bit ? 0xFF : 0))
277 status = ds2482_wait_1wire_idle(pdev);
278
279 mutex_unlock(&pdev->access_lock);
280
281 return (status & DS2482_REG_STS_SBR) ? 1 : 0;
282}
283
284/**
285 * 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 * @param data The ds2482 channel pointer
290 * @param 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, 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 dbit ? 0xFF : 0))
309 status = ds2482_wait_1wire_idle(pdev);
310
311 mutex_unlock(&pdev->access_lock);
312
313 /* Decode the status */
314 return (status >> 5);
315}
316
317/**
318 * Performs the write byte function.
319 *
320 * @param data The ds2482 channel pointer
321 * @param 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, 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(&pdev->access_lock);
339}
340
341/**
342 * Performs the read byte function.
343 *
344 * @param 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, 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(pdev->client);
371
372 mutex_unlock(&pdev->access_lock);
373
374 return result;
375}
376
377
378/**
379 * Sends a reset on the 1-wire interface
380 *
381 * @param 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, 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 ds2482_calculate_config(extra_config));
409 }
410
411 mutex_unlock(&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 ds2482_calculate_config(extra_config|DS2482_REG_CFG_SPU|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 const struct i2c_device_id *id)
444{
445 struct ds2482_data *data;
446 int err = -ENODEV;
447 int temp1;
448 int idx;
449
450 if (!i2c_check_functionality(client->adapter,
451 I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
452 I2C_FUNC_SMBUS_BYTE))
453 return -ENODEV;
454
455 if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
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(extra_config));
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 int 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 return 0;
539}
540
541/**
542 * Driver data (common to all clients)
543 */
544static const struct i2c_device_id ds2482_id[] = {
545 { "ds2482", 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");
562module_param(extra_config, int, S_IRUGO | S_IWUSR);
563MODULE_PARM_DESC(extra_config, "Extra Configuration settings 1=APU,2=PPM,3=SPU,8=1WS");
564
565MODULE_LICENSE("GPL");
566