2 * ds2482.c - provides i2c to w1-master bridge(s)
3 * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
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
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.
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>
24 #include "../w1_int.h"
27 * The DS2482 registers - there are 3 registers that are addressed by a read
28 * pointer. The read pointer is set by the last command executed.
30 * To read the data, issue a register read for any address
32 #define DS2482_CMD_RESET 0xF0 /* No param */
33 #define DS2482_CMD_SET_READ_PTR 0xE1 /* Param: DS2482_PTR_CODE_xxx */
34 #define DS2482_CMD_CHANNEL_SELECT 0xC3 /* Param: Channel byte - DS2482-800 only */
35 #define DS2482_CMD_WRITE_CONFIG 0xD2 /* Param: Config byte */
36 #define DS2482_CMD_1WIRE_RESET 0xB4 /* Param: None */
37 #define DS2482_CMD_1WIRE_SINGLE_BIT 0x87 /* Param: Bit byte (bit7) */
38 #define DS2482_CMD_1WIRE_WRITE_BYTE 0xA5 /* Param: Data byte */
39 #define DS2482_CMD_1WIRE_READ_BYTE 0x96 /* Param: None */
40 /* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
41 #define DS2482_CMD_1WIRE_TRIPLET 0x78 /* Param: Dir byte (bit7) */
43 /* Values for DS2482_CMD_SET_READ_PTR */
44 #define DS2482_PTR_CODE_STATUS 0xF0
45 #define DS2482_PTR_CODE_DATA 0xE1
46 #define DS2482_PTR_CODE_CHANNEL 0xD2 /* DS2482-800 only */
47 #define DS2482_PTR_CODE_CONFIG 0xC3
50 * Configure Register bit definitions
51 * The top 4 bits always read 0.
52 * To write, the top nibble must be the 1's compl. of the low nibble.
54 #define DS2482_REG_CFG_1WS 0x08 /* 1-wire speed */
55 #define DS2482_REG_CFG_SPU 0x04 /* strong pull-up */
56 #define DS2482_REG_CFG_PPM 0x02 /* presence pulse masking */
57 #define DS2482_REG_CFG_APU 0x01 /* active pull-up */
61 * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
62 * To set the channel, write the value at the index of the channel.
63 * Read and compare against the corresponding value to verify the change.
65 static const u8 ds2482_chan_wr[8] =
66 { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
67 static const u8 ds2482_chan_rd[8] =
68 { 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };
72 * Status Register bit definitions (read only)
74 #define DS2482_REG_STS_DIR 0x80
75 #define DS2482_REG_STS_TSB 0x40
76 #define DS2482_REG_STS_SBR 0x20
77 #define DS2482_REG_STS_RST 0x10
78 #define DS2482_REG_STS_LL 0x08
79 #define DS2482_REG_STS_SD 0x04
80 #define DS2482_REG_STS_PPD 0x02
81 #define DS2482_REG_STS_1WB 0x01
84 static int ds2482_probe(struct i2c_client *client,
85 const struct i2c_device_id *id);
86 static int ds2482_remove(struct i2c_client *client);
90 * Driver data (common to all clients)
92 static const struct i2c_device_id ds2482_id[] = {
96 MODULE_DEVICE_TABLE(i2c, ds2482_id);
98 static struct i2c_driver ds2482_driver = {
100 .owner = THIS_MODULE,
103 .probe = ds2482_probe,
104 .remove = ds2482_remove,
105 .id_table = ds2482_id,
109 * Client data (each client gets its own)
114 struct ds2482_w1_chan {
115 struct ds2482_data *pdev;
117 struct w1_bus_master w1_bm;
121 struct i2c_client *client;
122 struct mutex access_lock;
124 /* 1-wire interface(s) */
125 int w1_count; /* 1 or 8 */
126 struct ds2482_w1_chan w1_ch[8];
128 /* per-device values */
130 u8 read_prt; /* see DS2482_PTR_CODE_xxx */
136 * Helper to calculate values for configuration register
137 * @param conf the raw config value
138 * @return the value w/ complements that can be written to register
140 static inline u8 ds2482_calculate_config(u8 conf)
142 return conf | ((~conf & 0x0f) << 4);
147 * Sets the read pointer.
148 * @param pdev The ds2482 client pointer
149 * @param read_ptr see DS2482_PTR_CODE_xxx above
150 * @return -1 on failure, 0 on success
152 static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
154 if (pdev->read_prt != read_ptr) {
155 if (i2c_smbus_write_byte_data(pdev->client,
156 DS2482_CMD_SET_READ_PTR,
160 pdev->read_prt = read_ptr;
166 * Sends a command without a parameter
167 * @param pdev The ds2482 client pointer
168 * @param cmd DS2482_CMD_RESET,
169 * DS2482_CMD_1WIRE_RESET,
170 * DS2482_CMD_1WIRE_READ_BYTE
171 * @return -1 on failure, 0 on success
173 static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
175 if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
178 pdev->read_prt = DS2482_PTR_CODE_STATUS;
183 * Sends a command with a parameter
184 * @param pdev The ds2482 client pointer
185 * @param cmd DS2482_CMD_WRITE_CONFIG,
186 * DS2482_CMD_1WIRE_SINGLE_BIT,
187 * DS2482_CMD_1WIRE_WRITE_BYTE,
188 * DS2482_CMD_1WIRE_TRIPLET
189 * @param byte The data to send
190 * @return -1 on failure, 0 on success
192 static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
195 if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
198 /* all cmds leave in STATUS, except CONFIG */
199 pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
200 DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
206 * 1-Wire interface code
209 #define DS2482_WAIT_IDLE_TIMEOUT 100
212 * Waits until the 1-wire interface is idle (not busy)
214 * @param pdev Pointer to the device structure
215 * @return the last value read from status or -1 (failure)
217 static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
222 if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
224 temp = i2c_smbus_read_byte(pdev->client);
225 } while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
226 (++retries < DS2482_WAIT_IDLE_TIMEOUT));
229 if (retries >= DS2482_WAIT_IDLE_TIMEOUT)
230 pr_err("%s: timeout on channel %d\n",
231 __func__, pdev->channel);
237 * Selects a w1 channel.
238 * The 1-wire interface must be idle before calling this function.
240 * @param pdev The ds2482 client pointer
242 * @return -1 (failure) or 0 (success)
244 static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
246 if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
247 ds2482_chan_wr[channel]) < 0)
250 pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
252 if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
253 pdev->channel = channel;
261 * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
263 * @param data The ds2482 channel pointer
264 * @param bit The level to write: 0 or non-zero
265 * @return The level read: 0 or 1
267 static u8 ds2482_w1_touch_bit(void *data, u8 bit)
269 struct ds2482_w1_chan *pchan = data;
270 struct ds2482_data *pdev = pchan->pdev;
273 mutex_lock(&pdev->access_lock);
275 /* Select the channel */
276 ds2482_wait_1wire_idle(pdev);
277 if (pdev->w1_count > 1)
278 ds2482_set_channel(pdev, pchan->channel);
280 /* Send the touch command, wait until 1WB == 0, return the status */
281 if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
283 status = ds2482_wait_1wire_idle(pdev);
285 mutex_unlock(&pdev->access_lock);
287 return (status & DS2482_REG_STS_SBR) ? 1 : 0;
291 * Performs the triplet function, which reads two bits and writes a bit.
292 * The bit written is determined by the two reads:
293 * 00 => dbit, 01 => 0, 10 => 1
295 * @param data The ds2482 channel pointer
296 * @param dbit The direction to choose if both branches are valid
297 * @return b0=read1 b1=read2 b3=bit written
299 static u8 ds2482_w1_triplet(void *data, u8 dbit)
301 struct ds2482_w1_chan *pchan = data;
302 struct ds2482_data *pdev = pchan->pdev;
303 int status = (3 << 5);
305 mutex_lock(&pdev->access_lock);
307 /* Select the channel */
308 ds2482_wait_1wire_idle(pdev);
309 if (pdev->w1_count > 1)
310 ds2482_set_channel(pdev, pchan->channel);
312 /* Send the triplet command, wait until 1WB == 0, return the status */
313 if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
315 status = ds2482_wait_1wire_idle(pdev);
317 mutex_unlock(&pdev->access_lock);
319 /* Decode the status */
320 return (status >> 5);
324 * Performs the write byte function.
326 * @param data The ds2482 channel pointer
327 * @param byte The value to write
329 static void ds2482_w1_write_byte(void *data, u8 byte)
331 struct ds2482_w1_chan *pchan = data;
332 struct ds2482_data *pdev = pchan->pdev;
334 mutex_lock(&pdev->access_lock);
336 /* Select the channel */
337 ds2482_wait_1wire_idle(pdev);
338 if (pdev->w1_count > 1)
339 ds2482_set_channel(pdev, pchan->channel);
341 /* Send the write byte command */
342 ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
344 mutex_unlock(&pdev->access_lock);
348 * Performs the read byte function.
350 * @param data The ds2482 channel pointer
351 * @return The value read
353 static u8 ds2482_w1_read_byte(void *data)
355 struct ds2482_w1_chan *pchan = data;
356 struct ds2482_data *pdev = pchan->pdev;
359 mutex_lock(&pdev->access_lock);
361 /* Select the channel */
362 ds2482_wait_1wire_idle(pdev);
363 if (pdev->w1_count > 1)
364 ds2482_set_channel(pdev, pchan->channel);
366 /* Send the read byte command */
367 ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
369 /* Wait until 1WB == 0 */
370 ds2482_wait_1wire_idle(pdev);
372 /* Select the data register */
373 ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
375 /* Read the data byte */
376 result = i2c_smbus_read_byte(pdev->client);
378 mutex_unlock(&pdev->access_lock);
385 * Sends a reset on the 1-wire interface
387 * @param data The ds2482 channel pointer
388 * @return 0=Device present, 1=No device present or error
390 static u8 ds2482_w1_reset_bus(void *data)
392 struct ds2482_w1_chan *pchan = data;
393 struct ds2482_data *pdev = pchan->pdev;
397 mutex_lock(&pdev->access_lock);
399 /* Select the channel */
400 ds2482_wait_1wire_idle(pdev);
401 if (pdev->w1_count > 1)
402 ds2482_set_channel(pdev, pchan->channel);
404 /* Send the reset command */
405 err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
407 /* Wait until the reset is complete */
408 err = ds2482_wait_1wire_idle(pdev);
409 retval = !(err & DS2482_REG_STS_PPD);
411 /* If the chip did reset since detect, re-config it */
412 if (err & DS2482_REG_STS_RST)
413 ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
414 ds2482_calculate_config(0x00));
417 mutex_unlock(&pdev->access_lock);
422 static u8 ds2482_w1_set_pullup(void *data, int delay)
424 struct ds2482_w1_chan *pchan = data;
425 struct ds2482_data *pdev = pchan->pdev;
428 /* if delay is non-zero activate the pullup,
429 * the strong pullup will be automatically deactivated
430 * by the master, so do not explicitly deactive it
433 /* both waits are crucial, otherwise devices might not be
434 * powered long enough, causing e.g. a w1_therm sensor to
435 * provide wrong conversion results
437 ds2482_wait_1wire_idle(pdev);
438 /* note: it seems like both SPU and APU have to be set! */
439 retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
440 ds2482_calculate_config(DS2482_REG_CFG_SPU |
441 DS2482_REG_CFG_APU));
442 ds2482_wait_1wire_idle(pdev);
449 static int ds2482_probe(struct i2c_client *client,
450 const struct i2c_device_id *id)
452 struct ds2482_data *data;
457 if (!i2c_check_functionality(client->adapter,
458 I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
459 I2C_FUNC_SMBUS_BYTE))
462 if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
467 data->client = client;
468 i2c_set_clientdata(client, data);
470 /* Reset the device (sets the read_ptr to status) */
471 if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
472 dev_warn(&client->dev, "DS2482 reset failed.\n");
476 /* Sleep at least 525ns to allow the reset to complete */
479 /* Read the status byte - only reset bit and line should be set */
480 temp1 = i2c_smbus_read_byte(client);
481 if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
482 dev_warn(&client->dev, "DS2482 reset status "
483 "0x%02X - not a DS2482\n", temp1);
487 /* Detect the 8-port version */
489 if (ds2482_set_channel(data, 7) == 0)
492 /* Set all config items to 0 (off) */
493 ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG,
494 ds2482_calculate_config(0x00));
496 mutex_init(&data->access_lock);
498 /* Register 1-wire interface(s) */
499 for (idx = 0; idx < data->w1_count; idx++) {
500 data->w1_ch[idx].pdev = data;
501 data->w1_ch[idx].channel = idx;
503 /* Populate all the w1 bus master stuff */
504 data->w1_ch[idx].w1_bm.data = &data->w1_ch[idx];
505 data->w1_ch[idx].w1_bm.read_byte = ds2482_w1_read_byte;
506 data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
507 data->w1_ch[idx].w1_bm.touch_bit = ds2482_w1_touch_bit;
508 data->w1_ch[idx].w1_bm.triplet = ds2482_w1_triplet;
509 data->w1_ch[idx].w1_bm.reset_bus = ds2482_w1_reset_bus;
510 data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;
512 err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
514 data->w1_ch[idx].pdev = NULL;
522 for (idx = 0; idx < data->w1_count; idx++) {
523 if (data->w1_ch[idx].pdev != NULL)
524 w1_remove_master_device(&data->w1_ch[idx].w1_bm);
532 static int ds2482_remove(struct i2c_client *client)
534 struct ds2482_data *data = i2c_get_clientdata(client);
537 /* Unregister the 1-wire bridge(s) */
538 for (idx = 0; idx < data->w1_count; idx++) {
539 if (data->w1_ch[idx].pdev != NULL)
540 w1_remove_master_device(&data->w1_ch[idx].w1_bm);
543 /* Free the memory */
548 module_i2c_driver(ds2482_driver);
550 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
551 MODULE_DESCRIPTION("DS2482 driver");
552 MODULE_LICENSE("GPL");