1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * 1-Wire implementation for the ds2438 chip
4 *
5 * Copyright (c) 2017 Mariusz Bialonczyk <manio@skyboo.net>
6 */
7
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/device.h>
11#include <linux/types.h>
12#include <linux/delay.h>
13
14#include <linux/w1.h>
15
16#define W1_FAMILY_DS2438 0x26
17
18#define W1_DS2438_RETRIES 3
19
20/* Memory commands */
21#define W1_DS2438_READ_SCRATCH 0xBE
22#define W1_DS2438_WRITE_SCRATCH 0x4E
23#define W1_DS2438_COPY_SCRATCH 0x48
24#define W1_DS2438_RECALL_MEMORY 0xB8
25/* Register commands */
26#define W1_DS2438_CONVERT_TEMP 0x44
27#define W1_DS2438_CONVERT_VOLTAGE 0xB4
28
29#define DS2438_PAGE_SIZE 8
30#define DS2438_ADC_INPUT_VAD 0
31#define DS2438_ADC_INPUT_VDD 1
32#define DS2438_MAX_CONVERSION_TIME 10 /* ms */
33
34/* Page #0 definitions */
35#define DS2438_STATUS_REG 0x00 /* Status/Configuration Register */
36#define DS2438_STATUS_IAD (1 << 0) /* Current A/D Control Bit */
37#define DS2438_STATUS_CA (1 << 1) /* Current Accumulator Configuration */
38#define DS2438_STATUS_EE (1 << 2) /* Current Accumulator Shadow Selector bit */
39#define DS2438_STATUS_AD (1 << 3) /* Voltage A/D Input Select Bit */
40#define DS2438_STATUS_TB (1 << 4) /* Temperature Busy Flag */
41#define DS2438_STATUS_NVB (1 << 5) /* Nonvolatile Memory Busy Flag */
42#define DS2438_STATUS_ADB (1 << 6) /* A/D Converter Busy Flag */
43
44#define DS2438_TEMP_LSB 0x01
45#define DS2438_TEMP_MSB 0x02
46#define DS2438_VOLTAGE_LSB 0x03
47#define DS2438_VOLTAGE_MSB 0x04
48#define DS2438_CURRENT_LSB 0x05
49#define DS2438_CURRENT_MSB 0x06
50#define DS2438_THRESHOLD 0x07
51
52/* Page #1 definitions */
53#define DS2438_ETM_0 0x00
54#define DS2438_ETM_1 0x01
55#define DS2438_ETM_2 0x02
56#define DS2438_ETM_3 0x03
57#define DS2438_ICA 0x04
58#define DS2438_OFFSET_LSB 0x05
59#define DS2438_OFFSET_MSB 0x06
60
61static int w1_ds2438_get_page(struct w1_slave *sl, int pageno, u8 *buf)
62{
63 unsigned int retries = W1_DS2438_RETRIES;
64 u8 w1_buf[2];
65 u8 crc;
66 size_t count;
67
68 while (retries--) {
69 if (w1_reset_select_slave(sl))
70 continue;
71 w1_buf[0] = W1_DS2438_RECALL_MEMORY;
72 w1_buf[1] = (u8)pageno;
73 w1_write_block(sl->master, w1_buf, 2);
74
75 if (w1_reset_select_slave(sl))
76 continue;
77 w1_buf[0] = W1_DS2438_READ_SCRATCH;
78 w1_buf[1] = (u8)pageno;
79 w1_write_block(sl->master, w1_buf, 2);
80
81 count = w1_read_block(sl->master, buf, DS2438_PAGE_SIZE + 1);
82 if (count == DS2438_PAGE_SIZE + 1) {
83 crc = w1_calc_crc8(buf, DS2438_PAGE_SIZE);
84
85 /* check for correct CRC */
86 if ((u8)buf[DS2438_PAGE_SIZE] == crc)
87 return 0;
88 }
89 }
90 return -1;
91}
92
93static int w1_ds2438_get_temperature(struct w1_slave *sl, int16_t *temperature)
94{
95 unsigned int retries = W1_DS2438_RETRIES;
96 u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
97 unsigned int tm = DS2438_MAX_CONVERSION_TIME;
98 unsigned long sleep_rem;
99 int ret;
100
101 mutex_lock(&sl->master->bus_mutex);
102
103 while (retries--) {
104 if (w1_reset_select_slave(sl))
105 continue;
106 w1_write_8(sl->master, W1_DS2438_CONVERT_TEMP);
107
108 mutex_unlock(lock: &sl->master->bus_mutex);
109 sleep_rem = msleep_interruptible(msecs: tm);
110 if (sleep_rem != 0) {
111 ret = -1;
112 goto post_unlock;
113 }
114
115 if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0) {
116 ret = -1;
117 goto post_unlock;
118 }
119
120 break;
121 }
122
123 if (w1_ds2438_get_page(sl, pageno: 0, buf: w1_buf) == 0) {
124 *temperature = (((int16_t) w1_buf[DS2438_TEMP_MSB]) << 8) | ((uint16_t) w1_buf[DS2438_TEMP_LSB]);
125 ret = 0;
126 } else
127 ret = -1;
128
129 mutex_unlock(lock: &sl->master->bus_mutex);
130
131post_unlock:
132 return ret;
133}
134
135static int w1_ds2438_change_config_bit(struct w1_slave *sl, u8 mask, u8 value)
136{
137 unsigned int retries = W1_DS2438_RETRIES;
138 u8 w1_buf[3];
139 u8 status;
140 int perform_write = 0;
141
142 while (retries--) {
143 if (w1_reset_select_slave(sl))
144 continue;
145 w1_buf[0] = W1_DS2438_RECALL_MEMORY;
146 w1_buf[1] = 0x00;
147 w1_write_block(sl->master, w1_buf, 2);
148
149 if (w1_reset_select_slave(sl))
150 continue;
151 w1_buf[0] = W1_DS2438_READ_SCRATCH;
152 w1_buf[1] = 0x00;
153 w1_write_block(sl->master, w1_buf, 2);
154
155 /* reading one byte of result */
156 status = w1_read_8(sl->master);
157
158 /* if bit0=1, set a value to a mask for easy compare */
159 if (value)
160 value = mask;
161
162 if ((status & mask) == value)
163 return 0; /* already set as requested */
164
165 /* changing bit */
166 status ^= mask;
167 perform_write = 1;
168
169 break;
170 }
171
172 if (perform_write) {
173 retries = W1_DS2438_RETRIES;
174 while (retries--) {
175 if (w1_reset_select_slave(sl))
176 continue;
177 w1_buf[0] = W1_DS2438_WRITE_SCRATCH;
178 w1_buf[1] = 0x00;
179 w1_buf[2] = status;
180 w1_write_block(sl->master, w1_buf, 3);
181
182 if (w1_reset_select_slave(sl))
183 continue;
184 w1_buf[0] = W1_DS2438_COPY_SCRATCH;
185 w1_buf[1] = 0x00;
186 w1_write_block(sl->master, w1_buf, 2);
187
188 return 0;
189 }
190 }
191 return -1;
192}
193
194static int w1_ds2438_change_offset_register(struct w1_slave *sl, u8 *value)
195{
196 unsigned int retries = W1_DS2438_RETRIES;
197 u8 w1_buf[9];
198 u8 w1_page1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
199
200 if (w1_ds2438_get_page(sl, pageno: 1, buf: w1_page1_buf) == 0) {
201 memcpy(&w1_buf[2], w1_page1_buf, DS2438_PAGE_SIZE - 1); /* last register reserved */
202 w1_buf[7] = value[0]; /* change only offset register */
203 w1_buf[8] = value[1];
204 while (retries--) {
205 if (w1_reset_select_slave(sl))
206 continue;
207 w1_buf[0] = W1_DS2438_WRITE_SCRATCH;
208 w1_buf[1] = 0x01; /* write to page 1 */
209 w1_write_block(sl->master, w1_buf, 9);
210
211 if (w1_reset_select_slave(sl))
212 continue;
213 w1_buf[0] = W1_DS2438_COPY_SCRATCH;
214 w1_buf[1] = 0x01;
215 w1_write_block(sl->master, w1_buf, 2);
216 return 0;
217 }
218 }
219 return -1;
220}
221
222static int w1_ds2438_get_voltage(struct w1_slave *sl,
223 int adc_input, uint16_t *voltage)
224{
225 unsigned int retries = W1_DS2438_RETRIES;
226 u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
227 unsigned int tm = DS2438_MAX_CONVERSION_TIME;
228 unsigned long sleep_rem;
229 int ret;
230
231 mutex_lock(&sl->master->bus_mutex);
232
233 if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_AD, value: adc_input)) {
234 ret = -1;
235 goto pre_unlock;
236 }
237
238 while (retries--) {
239 if (w1_reset_select_slave(sl))
240 continue;
241 w1_write_8(sl->master, W1_DS2438_CONVERT_VOLTAGE);
242
243 mutex_unlock(lock: &sl->master->bus_mutex);
244 sleep_rem = msleep_interruptible(msecs: tm);
245 if (sleep_rem != 0) {
246 ret = -1;
247 goto post_unlock;
248 }
249
250 if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0) {
251 ret = -1;
252 goto post_unlock;
253 }
254
255 break;
256 }
257
258 if (w1_ds2438_get_page(sl, pageno: 0, buf: w1_buf) == 0) {
259 *voltage = (((uint16_t) w1_buf[DS2438_VOLTAGE_MSB]) << 8) | ((uint16_t) w1_buf[DS2438_VOLTAGE_LSB]);
260 ret = 0;
261 } else
262 ret = -1;
263
264pre_unlock:
265 mutex_unlock(lock: &sl->master->bus_mutex);
266
267post_unlock:
268 return ret;
269}
270
271static int w1_ds2438_get_current(struct w1_slave *sl, int16_t *voltage)
272{
273 u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
274 int ret;
275
276 mutex_lock(&sl->master->bus_mutex);
277
278 if (w1_ds2438_get_page(sl, pageno: 0, buf: w1_buf) == 0) {
279 /* The voltage measured across current sense resistor RSENS. */
280 *voltage = (((int16_t) w1_buf[DS2438_CURRENT_MSB]) << 8) | ((int16_t) w1_buf[DS2438_CURRENT_LSB]);
281 ret = 0;
282 } else
283 ret = -1;
284
285 mutex_unlock(lock: &sl->master->bus_mutex);
286
287 return ret;
288}
289
290static ssize_t iad_write(struct file *filp, struct kobject *kobj,
291 struct bin_attribute *bin_attr, char *buf,
292 loff_t off, size_t count)
293{
294 struct w1_slave *sl = kobj_to_w1_slave(kobj);
295 int ret;
296
297 if (count != 1 || off != 0)
298 return -EFAULT;
299
300 mutex_lock(&sl->master->bus_mutex);
301
302 if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_IAD, value: *buf & 0x01) == 0)
303 ret = 1;
304 else
305 ret = -EIO;
306
307 mutex_unlock(lock: &sl->master->bus_mutex);
308
309 return ret;
310}
311
312static ssize_t iad_read(struct file *filp, struct kobject *kobj,
313 struct bin_attribute *bin_attr, char *buf,
314 loff_t off, size_t count)
315{
316 struct w1_slave *sl = kobj_to_w1_slave(kobj);
317 int ret;
318 int16_t voltage;
319
320 if (off != 0)
321 return 0;
322 if (!buf)
323 return -EINVAL;
324
325 if (w1_ds2438_get_current(sl, voltage: &voltage) == 0)
326 ret = snprintf(buf, size: count, fmt: "%i\n", voltage);
327 else
328 ret = -EIO;
329
330 return ret;
331}
332
333static ssize_t page0_read(struct file *filp, struct kobject *kobj,
334 struct bin_attribute *bin_attr, char *buf,
335 loff_t off, size_t count)
336{
337 struct w1_slave *sl = kobj_to_w1_slave(kobj);
338 int ret;
339 u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
340
341 if (off != 0)
342 return 0;
343 if (!buf)
344 return -EINVAL;
345
346 mutex_lock(&sl->master->bus_mutex);
347
348 /* Read no more than page0 size */
349 if (count > DS2438_PAGE_SIZE)
350 count = DS2438_PAGE_SIZE;
351
352 if (w1_ds2438_get_page(sl, pageno: 0, buf: w1_buf) == 0) {
353 memcpy(buf, &w1_buf, count);
354 ret = count;
355 } else
356 ret = -EIO;
357
358 mutex_unlock(lock: &sl->master->bus_mutex);
359
360 return ret;
361}
362
363static ssize_t page1_read(struct file *filp, struct kobject *kobj,
364 struct bin_attribute *bin_attr, char *buf,
365 loff_t off, size_t count)
366{
367 struct w1_slave *sl = kobj_to_w1_slave(kobj);
368 int ret;
369 u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
370
371 if (off != 0)
372 return 0;
373 if (!buf)
374 return -EINVAL;
375
376 mutex_lock(&sl->master->bus_mutex);
377
378 /* Read no more than page1 size */
379 if (count > DS2438_PAGE_SIZE)
380 count = DS2438_PAGE_SIZE;
381
382 if (w1_ds2438_get_page(sl, pageno: 1, buf: w1_buf) == 0) {
383 memcpy(buf, &w1_buf, count);
384 ret = count;
385 } else
386 ret = -EIO;
387
388 mutex_unlock(lock: &sl->master->bus_mutex);
389
390 return ret;
391}
392
393static ssize_t offset_write(struct file *filp, struct kobject *kobj,
394 struct bin_attribute *bin_attr, char *buf,
395 loff_t off, size_t count)
396{
397 struct w1_slave *sl = kobj_to_w1_slave(kobj);
398 int ret;
399
400 mutex_lock(&sl->master->bus_mutex);
401
402 if (w1_ds2438_change_offset_register(sl, value: buf) == 0)
403 ret = count;
404 else
405 ret = -EIO;
406
407 mutex_unlock(lock: &sl->master->bus_mutex);
408
409 return ret;
410}
411
412static ssize_t temperature_read(struct file *filp, struct kobject *kobj,
413 struct bin_attribute *bin_attr, char *buf,
414 loff_t off, size_t count)
415{
416 struct w1_slave *sl = kobj_to_w1_slave(kobj);
417 int ret;
418 int16_t temp;
419
420 if (off != 0)
421 return 0;
422 if (!buf)
423 return -EINVAL;
424
425 if (w1_ds2438_get_temperature(sl, temperature: &temp) == 0)
426 ret = snprintf(buf, size: count, fmt: "%i\n", temp);
427 else
428 ret = -EIO;
429
430 return ret;
431}
432
433static ssize_t vad_read(struct file *filp, struct kobject *kobj,
434 struct bin_attribute *bin_attr, char *buf,
435 loff_t off, size_t count)
436{
437 struct w1_slave *sl = kobj_to_w1_slave(kobj);
438 int ret;
439 uint16_t voltage;
440
441 if (off != 0)
442 return 0;
443 if (!buf)
444 return -EINVAL;
445
446 if (w1_ds2438_get_voltage(sl, DS2438_ADC_INPUT_VAD, voltage: &voltage) == 0)
447 ret = snprintf(buf, size: count, fmt: "%u\n", voltage);
448 else
449 ret = -EIO;
450
451 return ret;
452}
453
454static ssize_t vdd_read(struct file *filp, struct kobject *kobj,
455 struct bin_attribute *bin_attr, char *buf,
456 loff_t off, size_t count)
457{
458 struct w1_slave *sl = kobj_to_w1_slave(kobj);
459 int ret;
460 uint16_t voltage;
461
462 if (off != 0)
463 return 0;
464 if (!buf)
465 return -EINVAL;
466
467 if (w1_ds2438_get_voltage(sl, DS2438_ADC_INPUT_VDD, voltage: &voltage) == 0)
468 ret = snprintf(buf, size: count, fmt: "%u\n", voltage);
469 else
470 ret = -EIO;
471
472 return ret;
473}
474
475static BIN_ATTR_RW(iad, 0);
476static BIN_ATTR_RO(page0, DS2438_PAGE_SIZE);
477static BIN_ATTR_RO(page1, DS2438_PAGE_SIZE);
478static BIN_ATTR_WO(offset, 2);
479static BIN_ATTR_RO(temperature, 0/* real length varies */);
480static BIN_ATTR_RO(vad, 0/* real length varies */);
481static BIN_ATTR_RO(vdd, 0/* real length varies */);
482
483static struct bin_attribute *w1_ds2438_bin_attrs[] = {
484 &bin_attr_iad,
485 &bin_attr_page0,
486 &bin_attr_page1,
487 &bin_attr_offset,
488 &bin_attr_temperature,
489 &bin_attr_vad,
490 &bin_attr_vdd,
491 NULL,
492};
493
494static const struct attribute_group w1_ds2438_group = {
495 .bin_attrs = w1_ds2438_bin_attrs,
496};
497
498static const struct attribute_group *w1_ds2438_groups[] = {
499 &w1_ds2438_group,
500 NULL,
501};
502
503static const struct w1_family_ops w1_ds2438_fops = {
504 .groups = w1_ds2438_groups,
505};
506
507static struct w1_family w1_ds2438_family = {
508 .fid = W1_FAMILY_DS2438,
509 .fops = &w1_ds2438_fops,
510};
511module_w1_family(w1_ds2438_family);
512
513MODULE_LICENSE("GPL");
514MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
515MODULE_DESCRIPTION("1-wire driver for Maxim/Dallas DS2438 Smart Battery Monitor");
516MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2438));
517

source code of linux/drivers/w1/slaves/w1_ds2438.c