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 "../w1.h"
24#include "../w1_int.h"
25
26/**
27 * Address is selected using 2 pins, resulting in 4 possible addresses.
28 *  0x18, 0x19, 0x1a, 0x1b
29 * However, the chip cannot be detected without doing an i2c write,
30 * so use the force module parameter.
31 */
32static unsigned short normal_i2c[] = {I2C_CLIENT_END};
33
34/**
35 * Insmod parameters
36 */
37I2C_CLIENT_INSMOD_1(ds2482);
38
39/**
40 * The DS2482 registers - there are 3 registers that are addressed by a read
41 * pointer. The read pointer is set by the last command executed.
42 *
43 * To read the data, issue a register read for any address
44 */
45#define DS2482_CMD_RESET		0xF0	/* No param */
46#define DS2482_CMD_SET_READ_PTR		0xE1	/* Param: DS2482_PTR_CODE_xxx */
47#define DS2482_CMD_CHANNEL_SELECT	0xC3	/* Param: Channel byte - DS2482-800 only */
48#define DS2482_CMD_WRITE_CONFIG		0xD2	/* Param: Config byte */
49#define DS2482_CMD_1WIRE_RESET		0xB4	/* Param: None */
50#define DS2482_CMD_1WIRE_SINGLE_BIT	0x87	/* Param: Bit byte (bit7) */
51#define DS2482_CMD_1WIRE_WRITE_BYTE	0xA5	/* Param: Data byte */
52#define DS2482_CMD_1WIRE_READ_BYTE	0x96	/* Param: None */
53/* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
54#define DS2482_CMD_1WIRE_TRIPLET	0x78	/* Param: Dir byte (bit7) */
55
56/* Values for DS2482_CMD_SET_READ_PTR */
57#define DS2482_PTR_CODE_STATUS		0xF0
58#define DS2482_PTR_CODE_DATA		0xE1
59#define DS2482_PTR_CODE_CHANNEL		0xD2	/* DS2482-800 only */
60#define DS2482_PTR_CODE_CONFIG		0xC3
61
62/**
63 * Configure Register bit definitions
64 * The top 4 bits always read 0.
65 * To write, the top nibble must be the 1's compl. of the low nibble.
66 */
67#define DS2482_REG_CFG_1WS		0x08
68#define DS2482_REG_CFG_SPU		0x04
69#define DS2482_REG_CFG_PPM		0x02
70#define DS2482_REG_CFG_APU		0x01
71
72
73/**
74 * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
75 * To set the channel, write the value at the index of the channel.
76 * Read and compare against the corresponding value to verify the change.
77 */
78static const u8 ds2482_chan_wr[8] =
79	{ 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
80static const u8 ds2482_chan_rd[8] =
81	{ 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
97static int ds2482_attach_adapter(struct i2c_adapter *adapter);
98static int ds2482_detect(struct i2c_adapter *adapter, int address, int kind);
99static int ds2482_detach_client(struct i2c_client *client);
100
101
102/**
103 * Driver data (common to all clients)
104 */
105static struct i2c_driver ds2482_driver = {
106	.driver = {
107		.owner	= THIS_MODULE,
108		.name	= "ds2482",
109	},
110	.attach_adapter	= ds2482_attach_adapter,
111	.detach_client	= ds2482_detach_client,
112};
113
114/*
115 * Client data (each client gets its own)
116 */
117
118struct ds2482_data;
119
120struct ds2482_w1_chan {
121	struct ds2482_data	*pdev;
122	u8			channel;
123	struct w1_bus_master	w1_bm;
124};
125
126struct ds2482_data {
127	struct i2c_client	client;
128	struct mutex		access_lock;
129
130	/* 1-wire interface(s) */
131	int			w1_count;	/* 1 or 8 */
132	struct ds2482_w1_chan	w1_ch[8];
133
134	/* per-device values */
135	u8			channel;
136	u8			read_prt;	/* see DS2482_PTR_CODE_xxx */
137	u8			reg_config;
138};
139
140
141/**
142 * Sets the read pointer.
143 * @param pdev		The ds2482 client pointer
144 * @param read_ptr	see DS2482_PTR_CODE_xxx above
145 * @return -1 on failure, 0 on success
146 */
147static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
148{
149	if (pdev->read_prt != read_ptr) {
150		if (i2c_smbus_write_byte_data(&pdev->client,
151					      DS2482_CMD_SET_READ_PTR,
152					      read_ptr) < 0)
153			return -1;
154
155		pdev->read_prt = read_ptr;
156	}
157	return 0;
158}
159
160/**
161 * Sends a command without a parameter
162 * @param pdev	The ds2482 client pointer
163 * @param cmd	DS2482_CMD_RESET,
164 *		DS2482_CMD_1WIRE_RESET,
165 *		DS2482_CMD_1WIRE_READ_BYTE
166 * @return -1 on failure, 0 on success
167 */
168static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
169{
170	if (i2c_smbus_write_byte(&pdev->client, cmd) < 0)
171		return -1;
172
173	pdev->read_prt = DS2482_PTR_CODE_STATUS;
174	return 0;
175}
176
177/**
178 * Sends a command with a parameter
179 * @param pdev	The ds2482 client pointer
180 * @param cmd	DS2482_CMD_WRITE_CONFIG,
181 *		DS2482_CMD_1WIRE_SINGLE_BIT,
182 *		DS2482_CMD_1WIRE_WRITE_BYTE,
183 *		DS2482_CMD_1WIRE_TRIPLET
184 * @param byte	The data to send
185 * @return -1 on failure, 0 on success
186 */
187static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
188				       u8 cmd, u8 byte)
189{
190	if (i2c_smbus_write_byte_data(&pdev->client, cmd, byte) < 0)
191		return -1;
192
193	/* all cmds leave in STATUS, except CONFIG */
194	pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
195			 DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
196	return 0;
197}
198
199
200/*
201 * 1-Wire interface code
202 */
203
204#define DS2482_WAIT_IDLE_TIMEOUT	100
205
206/**
207 * Waits until the 1-wire interface is idle (not busy)
208 *
209 * @param pdev Pointer to the device structure
210 * @return the last value read from status or -1 (failure)
211 */
212static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
213{
214	int temp = -1;
215	int retries = 0;
216
217	if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
218		do {
219			temp = i2c_smbus_read_byte(&pdev->client);
220		} while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
221			 (++retries < DS2482_WAIT_IDLE_TIMEOUT));
222	}
223
224	if (retries > DS2482_WAIT_IDLE_TIMEOUT)
225		printk(KERN_ERR "%s: timeout on channel %d\n",
226		       __func__, pdev->channel);
227
228	return temp;
229}
230
231/**
232 * Selects a w1 channel.
233 * The 1-wire interface must be idle before calling this function.
234 *
235 * @param pdev		The ds2482 client pointer
236 * @param channel	0-7
237 * @return		-1 (failure) or 0 (success)
238 */
239static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
240{
241	if (i2c_smbus_write_byte_data(&pdev->client, DS2482_CMD_CHANNEL_SELECT,
242				      ds2482_chan_wr[channel]) < 0)
243		return -1;
244
245	pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
246	pdev->channel = -1;
247	if (i2c_smbus_read_byte(&pdev->client) == ds2482_chan_rd[channel]) {
248		pdev->channel = channel;
249		return 0;
250	}
251	return -1;
252}
253
254
255/**
256 * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
257 *
258 * @param data	The ds2482 channel pointer
259 * @param bit	The level to write: 0 or non-zero
260 * @return	The level read: 0 or 1
261 */
262static u8 ds2482_w1_touch_bit(void *data, u8 bit)
263{
264	struct ds2482_w1_chan *pchan = data;
265	struct ds2482_data    *pdev = pchan->pdev;
266	int status = -1;
267
268	mutex_lock(&pdev->access_lock);
269
270	/* Select the channel */
271	ds2482_wait_1wire_idle(pdev);
272	if (pdev->w1_count > 1)
273		ds2482_set_channel(pdev, pchan->channel);
274
275	/* Send the touch command, wait until 1WB == 0, return the status */
276	if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
277				  bit ? 0xFF : 0))
278		status = ds2482_wait_1wire_idle(pdev);
279
280	mutex_unlock(&pdev->access_lock);
281
282	return (status & DS2482_REG_STS_SBR) ? 1 : 0;
283}
284
285/**
286 * Performs the triplet function, which reads two bits and writes a bit.
287 * The bit written is determined by the two reads:
288 *   00 => dbit, 01 => 0, 10 => 1
289 *
290 * @param data	The ds2482 channel pointer
291 * @param dbit	The direction to choose if both branches are valid
292 * @return	b0=read1 b1=read2 b3=bit written
293 */
294static u8 ds2482_w1_triplet(void *data, u8 dbit)
295{
296	struct ds2482_w1_chan *pchan = data;
297	struct ds2482_data    *pdev = pchan->pdev;
298	int status = (3 << 5);
299
300	mutex_lock(&pdev->access_lock);
301
302	/* Select the channel */
303	ds2482_wait_1wire_idle(pdev);
304	if (pdev->w1_count > 1)
305		ds2482_set_channel(pdev, pchan->channel);
306
307	/* Send the triplet command, wait until 1WB == 0, return the status */
308	if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
309				  dbit ? 0xFF : 0))
310		status = ds2482_wait_1wire_idle(pdev);
311
312	mutex_unlock(&pdev->access_lock);
313
314	/* Decode the status */
315	return (status >> 5);
316}
317
318/**
319 * Performs the write byte function.
320 *
321 * @param data	The ds2482 channel pointer
322 * @param byte	The value to write
323 */
324static void ds2482_w1_write_byte(void *data, u8 byte)
325{
326	struct ds2482_w1_chan *pchan = data;
327	struct ds2482_data    *pdev = pchan->pdev;
328
329	mutex_lock(&pdev->access_lock);
330
331	/* Select the channel */
332	ds2482_wait_1wire_idle(pdev);
333	if (pdev->w1_count > 1)
334		ds2482_set_channel(pdev, pchan->channel);
335
336	/* Send the write byte command */
337	ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
338
339	mutex_unlock(&pdev->access_lock);
340}
341
342/**
343 * Performs the read byte function.
344 *
345 * @param data	The ds2482 channel pointer
346 * @return	The value read
347 */
348static u8 ds2482_w1_read_byte(void *data)
349{
350	struct ds2482_w1_chan *pchan = data;
351	struct ds2482_data    *pdev = pchan->pdev;
352	int result;
353
354	mutex_lock(&pdev->access_lock);
355
356	/* Select the channel */
357	ds2482_wait_1wire_idle(pdev);
358	if (pdev->w1_count > 1)
359		ds2482_set_channel(pdev, pchan->channel);
360
361	/* Send the read byte command */
362	ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
363
364	/* Wait until 1WB == 0 */
365	ds2482_wait_1wire_idle(pdev);
366
367	/* Select the data register */
368	ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
369
370	/* Read the data byte */
371	result = i2c_smbus_read_byte(&pdev->client);
372
373	mutex_unlock(&pdev->access_lock);
374
375	return result;
376}
377
378
379/**
380 * Sends a reset on the 1-wire interface
381 *
382 * @param data	The ds2482 channel pointer
383 * @return	0=Device present, 1=No device present or error
384 */
385static u8 ds2482_w1_reset_bus(void *data)
386{
387	struct ds2482_w1_chan *pchan = data;
388	struct ds2482_data    *pdev = pchan->pdev;
389	int err;
390	u8 retval = 1;
391
392	mutex_lock(&pdev->access_lock);
393
394	/* Select the channel */
395	ds2482_wait_1wire_idle(pdev);
396	if (pdev->w1_count > 1)
397		ds2482_set_channel(pdev, pchan->channel);
398
399	/* Send the reset command */
400	err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
401	if (err >= 0) {
402		/* Wait until the reset is complete */
403		err = ds2482_wait_1wire_idle(pdev);
404		retval = !(err & DS2482_REG_STS_PPD);
405
406		/* If the chip did reset since detect, re-config it */
407		if (err & DS2482_REG_STS_RST)
408			ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
409					     0xF0);
410	}
411
412	mutex_unlock(&pdev->access_lock);
413
414	return retval;
415}
416
417
418/**
419 * Called to see if the device exists on an i2c bus.
420 */
421static int ds2482_attach_adapter(struct i2c_adapter *adapter)
422{
423	return i2c_probe(adapter, &addr_data, ds2482_detect);
424}
425
426
427/*
428 * The following function does more than just detection. If detection
429 * succeeds, it also registers the new chip.
430 */
431static int ds2482_detect(struct i2c_adapter *adapter, int address, int kind)
432{
433	struct ds2482_data *data;
434	struct i2c_client  *new_client;
435	int err = 0;
436	int temp1;
437	int idx;
438
439	if (!i2c_check_functionality(adapter,
440				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
441				     I2C_FUNC_SMBUS_BYTE))
442		goto exit;
443
444	if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
445		err = -ENOMEM;
446		goto exit;
447	}
448
449	new_client = &data->client;
450	i2c_set_clientdata(new_client, data);
451	new_client->addr = address;
452	new_client->driver = &ds2482_driver;
453	new_client->adapter = adapter;
454
455	/* Reset the device (sets the read_ptr to status) */
456	if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
457		dev_dbg(&adapter->dev, "DS2482 reset failed at 0x%02x.\n",
458			address);
459		goto exit_free;
460	}
461
462	/* Sleep at least 525ns to allow the reset to complete */
463	ndelay(525);
464
465	/* Read the status byte - only reset bit and line should be set */
466	temp1 = i2c_smbus_read_byte(new_client);
467	if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
468		dev_dbg(&adapter->dev, "DS2482 (0x%02x) reset status "
469			"0x%02X - not a DS2482\n", address, temp1);
470		goto exit_free;
471	}
472
473	/* Detect the 8-port version */
474	data->w1_count = 1;
475	if (ds2482_set_channel(data, 7) == 0)
476		data->w1_count = 8;
477
478	/* Set all config items to 0 (off) */
479	ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG, 0xF0);
480
481	/* We can fill in the remaining client fields */
482	snprintf(new_client->name, sizeof(new_client->name), "ds2482-%d00",
483		 data->w1_count);
484
485	mutex_init(&data->access_lock);
486
487	/* Tell the I2C layer a new client has arrived */
488	if ((err = i2c_attach_client(new_client)))
489		goto exit_free;
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
504		err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
505		if (err) {
506			data->w1_ch[idx].pdev = NULL;
507			goto exit_w1_remove;
508		}
509	}
510
511	return 0;
512
513exit_w1_remove:
514	i2c_detach_client(new_client);
515
516	for (idx = 0; idx < data->w1_count; idx++) {
517		if (data->w1_ch[idx].pdev != NULL)
518			w1_remove_master_device(&data->w1_ch[idx].w1_bm);
519	}
520exit_free:
521	kfree(data);
522exit:
523	return err;
524}
525
526static int ds2482_detach_client(struct i2c_client *client)
527{
528	struct ds2482_data   *data = i2c_get_clientdata(client);
529	int err, 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(&data->w1_ch[idx].w1_bm);
535	}
536
537	/* Detach the i2c device */
538	if ((err = i2c_detach_client(client))) {
539		dev_err(&client->dev,
540			"Deregistration failed, client not detached.\n");
541		return err;
542	}
543
544	/* Free the memory */
545	kfree(data);
546	return 0;
547}
548
549static int __init sensors_ds2482_init(void)
550{
551	return i2c_add_driver(&ds2482_driver);
552}
553
554static void __exit sensors_ds2482_exit(void)
555{
556	i2c_del_driver(&ds2482_driver);
557}
558
559MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
560MODULE_DESCRIPTION("DS2482 driver");
561MODULE_LICENSE("GPL");
562
563module_init(sensors_ds2482_init);
564module_exit(sensors_ds2482_exit);
565