564 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*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/438211 */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-rate26 * transistor) or a passive pullup (Rwpu resistor) will be used to drive27 * a 1-Wire line from low to high. When APU = 0, active pullup is disabled28 * (resistor mode). Active Pullup should always be selected unless there is29 * only a single slave on the 1-Wire line.30 */31static int ds2482_active_pullup = 1;32module_param_named(active_pullup, ds2482_active_pullup, int, 0644);33MODULE_PARM_DESC(active_pullup, "Active pullup (apply to all buses): " \34 "0-disable, 1-enable (default)");35 36/* extra configurations - e.g. 1WS */37static int extra_config;38module_param(extra_config, int, 0644);39MODULE_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 read43 * pointer. The read pointer is set by the last command executed.44 *45 * To read the data, issue a register read for any address46 */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 0xF060#define DS2482_PTR_CODE_DATA 0xE161#define DS2482_PTR_CODE_CHANNEL 0xD2 /* DS2482-800 only */62#define DS2482_PTR_CODE_CONFIG 0xC363 64/*65 * Configure Register bit definitions66 * 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 */80static const u8 ds2482_chan_wr[8] = { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };81static 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 0x8088#define DS2482_REG_STS_TSB 0x4089#define DS2482_REG_STS_SBR 0x2090#define DS2482_REG_STS_RST 0x1091#define DS2482_REG_STS_LL 0x0892#define DS2482_REG_STS_SD 0x0493#define DS2482_REG_STS_PPD 0x0294#define DS2482_REG_STS_1WB 0x0195 96/*97 * Client data (each client gets its own)98 */99 100struct ds2482_data;101 102struct ds2482_w1_chan {103 struct ds2482_data *pdev;104 u8 channel;105 struct w1_bus_master w1_bm;106};107 108struct 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 register125 * @conf: the raw config value126 * Return: the value w/ complements that can be written to register127 */128static 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 pointer142 * @read_ptr: see DS2482_PTR_CODE_xxx above143 * Return: -1 on failure, 0 on success144 */145static 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 parameter160 * @pdev: The ds2482 client pointer161 * @cmd: DS2482_CMD_RESET,162 * DS2482_CMD_1WIRE_RESET,163 * DS2482_CMD_1WIRE_READ_BYTE164 * Return: -1 on failure, 0 on success165 */166static 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 parameter177 * @pdev: The ds2482 client pointer178 * @cmd: DS2482_CMD_WRITE_CONFIG,179 * DS2482_CMD_1WIRE_SINGLE_BIT,180 * DS2482_CMD_1WIRE_WRITE_BYTE,181 * DS2482_CMD_1WIRE_TRIPLET182 * @byte: The data to send183 * Return: -1 on failure, 0 on success184 */185static 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 code200 */201 202#define DS2482_WAIT_IDLE_TIMEOUT 100203 204/**205 * ds2482_wait_1wire_idle - Waits until the 1-wire interface is idle (not busy)206 *207 * @pdev: Pointer to the device structure208 * Return: the last value read from status or -1 (failure)209 */210static 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 pointer234 * @channel: 0-7235 * Return: -1 (failure) or 0 (success)236 */237static 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 pointer257 * @bit: The level to write: 0 or non-zero258 * Return: The level read: 0 or 1259 */260static 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 => 1287 *288 * @data: The ds2482 channel pointer289 * @dbit: The direction to choose if both branches are valid290 * Return: b0=read1 b1=read2 b3=bit written291 */292static 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 pointer320 * @byte: The value to write321 */322static 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 pointer344 * Return: The value read345 */346static 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 interface379 *380 * @data: The ds2482 channel pointer381 * Return: 0=Device present, 1=No device present or error382 */383static 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 415static 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 deactivated423 * by the master, so do not explicitly deactive it424 */425 if (delay) {426 /* both waits are crucial, otherwise devices might not be427 * powered long enough, causing e.g. a w1_therm sensor to428 * provide wrong conversion results429 */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 442static 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 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 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 */543static const struct i2c_device_id ds2482_id[] = {544 { "ds2482" },545 { "ds2484" },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");562 563MODULE_LICENSE("GPL");564