ds2482.c

  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(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 * 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(pdev->client, 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(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 * 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(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(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 * 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, 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 * 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, 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 * 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, 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 * 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, 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 * 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, 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(0x00));
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(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(client->adapter,
452				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
453				     I2C_FUNC_SMBUS_BYTE))
454		return -ENODEV;
455
456	data = devm_kzalloc(&client->dev, sizeof(struct ds2482_data), GFP_KERNEL);
457	if (!data)
458		return -ENOMEM;
459
460	ret = devm_regulator_get_enable(&client->dev, "vcc");
461	if (ret)
462		return dev_err_probe(&client->dev, ret, "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(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(data, 7) == 0)
487		data->w1_count = 8;
488
489	/* Set all config items to 0 (off) */
490	ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG,
491		ds2482_calculate_config(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(&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(&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(&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");