1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Driver for Jedec 5118 compliant temperature sensors
4 *
5 * Derived from https://github.com/Steve-Tech/SPD5118-DKMS
6 * Originally from T/2 driver at https://t2sde.org/packages/linux
7 * Copyright (c) 2023 René Rebe, ExactCODE GmbH; Germany.
8 *
9 * Copyright (c) 2024 Guenter Roeck
10 *
11 * Inspired by ee1004.c and jc42.c.
12 *
13 * SPD5118 compliant temperature sensors are typically used on DDR5
14 * memory modules.
15 */
16
17#include <linux/bitops.h>
18#include <linux/bits.h>
19#include <linux/err.h>
20#include <linux/i2c.h>
21#include <linux/hwmon.h>
22#include <linux/module.h>
23#include <linux/mutex.h>
24#include <linux/nvmem-provider.h>
25#include <linux/pm.h>
26#include <linux/regmap.h>
27#include <linux/units.h>
28
29/* Addresses to scan */
30static const unsigned short normal_i2c[] = {
31 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, I2C_CLIENT_END };
32
33/* SPD5118 registers. */
34#define SPD5118_REG_TYPE 0x00 /* MR0:MR1 */
35#define SPD5118_REG_REVISION 0x02 /* MR2 */
36#define SPD5118_REG_VENDOR 0x03 /* MR3:MR4 */
37#define SPD5118_REG_CAPABILITY 0x05 /* MR5 */
38#define SPD5118_REG_I2C_LEGACY_MODE 0x0B /* MR11 */
39#define SPD5118_REG_TEMP_CLR 0x13 /* MR19 */
40#define SPD5118_REG_ERROR_CLR 0x14 /* MR20 */
41#define SPD5118_REG_TEMP_CONFIG 0x1A /* MR26 */
42#define SPD5118_REG_TEMP_MAX 0x1c /* MR28:MR29 */
43#define SPD5118_REG_TEMP_MIN 0x1e /* MR30:MR31 */
44#define SPD5118_REG_TEMP_CRIT 0x20 /* MR32:MR33 */
45#define SPD5118_REG_TEMP_LCRIT 0x22 /* MR34:MR35 */
46#define SPD5118_REG_TEMP 0x31 /* MR49:MR50 */
47#define SPD5118_REG_TEMP_STATUS 0x33 /* MR51 */
48
49#define SPD5118_TEMP_STATUS_HIGH BIT(0)
50#define SPD5118_TEMP_STATUS_LOW BIT(1)
51#define SPD5118_TEMP_STATUS_CRIT BIT(2)
52#define SPD5118_TEMP_STATUS_LCRIT BIT(3)
53
54#define SPD5118_CAP_TS_SUPPORT BIT(1) /* temperature sensor support */
55
56#define SPD5118_TS_DISABLE BIT(0) /* temperature sensor disable */
57
58#define SPD5118_LEGACY_MODE_ADDR BIT(3)
59#define SPD5118_LEGACY_PAGE_MASK GENMASK(2, 0)
60#define SPD5118_LEGACY_MODE_MASK (SPD5118_LEGACY_MODE_ADDR | SPD5118_LEGACY_PAGE_MASK)
61
62#define SPD5118_NUM_PAGES 8
63#define SPD5118_PAGE_SIZE 128
64#define SPD5118_PAGE_SHIFT 7
65#define SPD5118_PAGE_MASK GENMASK(6, 0)
66#define SPD5118_EEPROM_BASE 0x80
67#define SPD5118_EEPROM_SIZE (SPD5118_PAGE_SIZE * SPD5118_NUM_PAGES)
68
69#define PAGE_ADDR0(page) (((page) & BIT(0)) << 6)
70#define PAGE_ADDR1_4(page) (((page) & GENMASK(4, 1)) >> 1)
71
72/* Temperature unit in millicelsius */
73#define SPD5118_TEMP_UNIT (MILLIDEGREE_PER_DEGREE / 4)
74/* Representable temperature range in millicelsius */
75#define SPD5118_TEMP_RANGE_MIN -256000
76#define SPD5118_TEMP_RANGE_MAX 255750
77
78struct spd5118_data {
79 struct regmap *regmap;
80 struct mutex nvmem_lock;
81 bool is_16bit;
82};
83
84/* hwmon */
85
86static int spd5118_temp_from_reg(u16 reg)
87{
88 int temp = sign_extend32(value: reg >> 2, index: 10);
89
90 return temp * SPD5118_TEMP_UNIT;
91}
92
93static u16 spd5118_temp_to_reg(long temp)
94{
95 temp = clamp_val(temp, SPD5118_TEMP_RANGE_MIN, SPD5118_TEMP_RANGE_MAX);
96 return (DIV_ROUND_CLOSEST(temp, SPD5118_TEMP_UNIT) & 0x7ff) << 2;
97}
98
99static int spd5118_read_temp(struct regmap *regmap, u32 attr, long *val)
100{
101 int reg, err;
102 u8 regval[2];
103 u16 temp;
104
105 switch (attr) {
106 case hwmon_temp_input:
107 reg = SPD5118_REG_TEMP;
108 break;
109 case hwmon_temp_max:
110 reg = SPD5118_REG_TEMP_MAX;
111 break;
112 case hwmon_temp_min:
113 reg = SPD5118_REG_TEMP_MIN;
114 break;
115 case hwmon_temp_crit:
116 reg = SPD5118_REG_TEMP_CRIT;
117 break;
118 case hwmon_temp_lcrit:
119 reg = SPD5118_REG_TEMP_LCRIT;
120 break;
121 default:
122 return -EOPNOTSUPP;
123 }
124
125 err = regmap_bulk_read(map: regmap, reg, val: regval, val_count: 2);
126 if (err)
127 return err;
128
129 temp = (regval[1] << 8) | regval[0];
130
131 *val = spd5118_temp_from_reg(reg: temp);
132 return 0;
133}
134
135static int spd5118_read_alarm(struct regmap *regmap, u32 attr, long *val)
136{
137 unsigned int mask, regval;
138 int err;
139
140 switch (attr) {
141 case hwmon_temp_max_alarm:
142 mask = SPD5118_TEMP_STATUS_HIGH;
143 break;
144 case hwmon_temp_min_alarm:
145 mask = SPD5118_TEMP_STATUS_LOW;
146 break;
147 case hwmon_temp_crit_alarm:
148 mask = SPD5118_TEMP_STATUS_CRIT;
149 break;
150 case hwmon_temp_lcrit_alarm:
151 mask = SPD5118_TEMP_STATUS_LCRIT;
152 break;
153 default:
154 return -EOPNOTSUPP;
155 }
156
157 err = regmap_read(map: regmap, SPD5118_REG_TEMP_STATUS, val: &regval);
158 if (err < 0)
159 return err;
160 *val = !!(regval & mask);
161 if (*val)
162 return regmap_write(map: regmap, SPD5118_REG_TEMP_CLR, val: mask);
163 return 0;
164}
165
166static int spd5118_read_enable(struct regmap *regmap, long *val)
167{
168 u32 regval;
169 int err;
170
171 err = regmap_read(map: regmap, SPD5118_REG_TEMP_CONFIG, val: &regval);
172 if (err < 0)
173 return err;
174 *val = !(regval & SPD5118_TS_DISABLE);
175 return 0;
176}
177
178static int spd5118_read(struct device *dev, enum hwmon_sensor_types type,
179 u32 attr, int channel, long *val)
180{
181 struct regmap *regmap = dev_get_drvdata(dev);
182
183 if (type != hwmon_temp)
184 return -EOPNOTSUPP;
185
186 switch (attr) {
187 case hwmon_temp_input:
188 case hwmon_temp_max:
189 case hwmon_temp_min:
190 case hwmon_temp_crit:
191 case hwmon_temp_lcrit:
192 return spd5118_read_temp(regmap, attr, val);
193 case hwmon_temp_max_alarm:
194 case hwmon_temp_min_alarm:
195 case hwmon_temp_crit_alarm:
196 case hwmon_temp_lcrit_alarm:
197 return spd5118_read_alarm(regmap, attr, val);
198 case hwmon_temp_enable:
199 return spd5118_read_enable(regmap, val);
200 default:
201 return -EOPNOTSUPP;
202 }
203}
204
205static int spd5118_write_temp(struct regmap *regmap, u32 attr, long val)
206{
207 u8 regval[2];
208 u16 temp;
209 int reg;
210
211 switch (attr) {
212 case hwmon_temp_max:
213 reg = SPD5118_REG_TEMP_MAX;
214 break;
215 case hwmon_temp_min:
216 reg = SPD5118_REG_TEMP_MIN;
217 break;
218 case hwmon_temp_crit:
219 reg = SPD5118_REG_TEMP_CRIT;
220 break;
221 case hwmon_temp_lcrit:
222 reg = SPD5118_REG_TEMP_LCRIT;
223 break;
224 default:
225 return -EOPNOTSUPP;
226 }
227
228 temp = spd5118_temp_to_reg(temp: val);
229 regval[0] = temp & 0xff;
230 regval[1] = temp >> 8;
231
232 return regmap_bulk_write(map: regmap, reg, val: regval, val_count: 2);
233}
234
235static int spd5118_write_enable(struct regmap *regmap, long val)
236{
237 if (val && val != 1)
238 return -EINVAL;
239
240 return regmap_update_bits(map: regmap, SPD5118_REG_TEMP_CONFIG,
241 SPD5118_TS_DISABLE,
242 val: val ? 0 : SPD5118_TS_DISABLE);
243}
244
245static int spd5118_temp_write(struct regmap *regmap, u32 attr, long val)
246{
247 switch (attr) {
248 case hwmon_temp_max:
249 case hwmon_temp_min:
250 case hwmon_temp_crit:
251 case hwmon_temp_lcrit:
252 return spd5118_write_temp(regmap, attr, val);
253 case hwmon_temp_enable:
254 return spd5118_write_enable(regmap, val);
255 default:
256 return -EOPNOTSUPP;
257 }
258}
259
260static int spd5118_write(struct device *dev, enum hwmon_sensor_types type,
261 u32 attr, int channel, long val)
262{
263 struct regmap *regmap = dev_get_drvdata(dev);
264
265 switch (type) {
266 case hwmon_temp:
267 return spd5118_temp_write(regmap, attr, val);
268 default:
269 return -EOPNOTSUPP;
270 }
271}
272
273static umode_t spd5118_is_visible(const void *_data, enum hwmon_sensor_types type,
274 u32 attr, int channel)
275{
276 if (type != hwmon_temp)
277 return 0;
278
279 switch (attr) {
280 case hwmon_temp_input:
281 return 0444;
282 case hwmon_temp_min:
283 case hwmon_temp_max:
284 case hwmon_temp_lcrit:
285 case hwmon_temp_crit:
286 case hwmon_temp_enable:
287 return 0644;
288 case hwmon_temp_min_alarm:
289 case hwmon_temp_max_alarm:
290 case hwmon_temp_crit_alarm:
291 case hwmon_temp_lcrit_alarm:
292 return 0444;
293 default:
294 return 0;
295 }
296}
297
298/*
299 * Bank and vendor id are 8-bit fields with seven data bits and odd parity.
300 * Vendor IDs 0 and 0x7f are invalid.
301 * See Jedec standard JEP106BJ for details and a list of assigned vendor IDs.
302 */
303static bool spd5118_vendor_valid(u8 bank, u8 id)
304{
305 if (parity8(val: bank) == 0 || parity8(val: id) == 0)
306 return false;
307
308 id &= 0x7f;
309 return id && id != 0x7f;
310}
311
312static const struct hwmon_channel_info *spd5118_info[] = {
313 HWMON_CHANNEL_INFO(chip,
314 HWMON_C_REGISTER_TZ),
315 HWMON_CHANNEL_INFO(temp,
316 HWMON_T_INPUT |
317 HWMON_T_LCRIT | HWMON_T_LCRIT_ALARM |
318 HWMON_T_MIN | HWMON_T_MIN_ALARM |
319 HWMON_T_MAX | HWMON_T_MAX_ALARM |
320 HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
321 HWMON_T_ENABLE),
322 NULL
323};
324
325static const struct hwmon_ops spd5118_hwmon_ops = {
326 .is_visible = spd5118_is_visible,
327 .read = spd5118_read,
328 .write = spd5118_write,
329};
330
331static const struct hwmon_chip_info spd5118_chip_info = {
332 .ops = &spd5118_hwmon_ops,
333 .info = spd5118_info,
334};
335
336/* nvmem */
337
338static ssize_t spd5118_nvmem_read_page(struct spd5118_data *data, char *buf,
339 unsigned int offset, size_t count)
340{
341 int page = offset >> SPD5118_PAGE_SHIFT;
342 struct regmap *regmap = data->regmap;
343 int err, addr;
344
345 offset &= SPD5118_PAGE_MASK;
346
347 /* Can't cross page boundaries */
348 if (offset + count > SPD5118_PAGE_SIZE)
349 count = SPD5118_PAGE_SIZE - offset;
350
351 if (data->is_16bit) {
352 addr = SPD5118_EEPROM_BASE | PAGE_ADDR0(page) |
353 (PAGE_ADDR1_4(page) << 8);
354 } else {
355 addr = page * 0x100 + SPD5118_EEPROM_BASE;
356 }
357 err = regmap_bulk_read(map: regmap, reg: addr + offset, val: buf, val_count: count);
358 if (err)
359 return err;
360
361 return count;
362}
363
364static int spd5118_nvmem_read(void *priv, unsigned int off, void *val, size_t count)
365{
366 struct spd5118_data *data = priv;
367 char *buf = val;
368 int ret;
369
370 if (unlikely(!count))
371 return count;
372
373 if (off + count > SPD5118_EEPROM_SIZE)
374 return -EINVAL;
375
376 mutex_lock(&data->nvmem_lock);
377
378 while (count) {
379 ret = spd5118_nvmem_read_page(data, buf, offset: off, count);
380 if (ret < 0) {
381 mutex_unlock(lock: &data->nvmem_lock);
382 return ret;
383 }
384 buf += ret;
385 off += ret;
386 count -= ret;
387 }
388 mutex_unlock(lock: &data->nvmem_lock);
389 return 0;
390}
391
392static int spd5118_nvmem_init(struct device *dev, struct spd5118_data *data)
393{
394 struct nvmem_config nvmem_config = {
395 .type = NVMEM_TYPE_EEPROM,
396 .name = dev_name(dev),
397 .id = NVMEM_DEVID_NONE,
398 .dev = dev,
399 .base_dev = dev,
400 .read_only = true,
401 .root_only = false,
402 .owner = THIS_MODULE,
403 .compat = true,
404 .reg_read = spd5118_nvmem_read,
405 .priv = data,
406 .stride = 1,
407 .word_size = 1,
408 .size = SPD5118_EEPROM_SIZE,
409 };
410 struct nvmem_device *nvmem;
411
412 nvmem = devm_nvmem_register(dev, cfg: &nvmem_config);
413 return PTR_ERR_OR_ZERO(ptr: nvmem);
414}
415
416/* regmap */
417
418static bool spd5118_writeable_reg(struct device *dev, unsigned int reg)
419{
420 switch (reg) {
421 case SPD5118_REG_I2C_LEGACY_MODE:
422 case SPD5118_REG_TEMP_CLR:
423 case SPD5118_REG_TEMP_CONFIG:
424 case SPD5118_REG_TEMP_MAX:
425 case SPD5118_REG_TEMP_MAX + 1:
426 case SPD5118_REG_TEMP_MIN:
427 case SPD5118_REG_TEMP_MIN + 1:
428 case SPD5118_REG_TEMP_CRIT:
429 case SPD5118_REG_TEMP_CRIT + 1:
430 case SPD5118_REG_TEMP_LCRIT:
431 case SPD5118_REG_TEMP_LCRIT + 1:
432 return true;
433 default:
434 return false;
435 }
436}
437
438static bool spd5118_volatile_reg(struct device *dev, unsigned int reg)
439{
440 switch (reg) {
441 case SPD5118_REG_TEMP_CLR:
442 case SPD5118_REG_ERROR_CLR:
443 case SPD5118_REG_TEMP:
444 case SPD5118_REG_TEMP + 1:
445 case SPD5118_REG_TEMP_STATUS:
446 return true;
447 default:
448 return false;
449 }
450}
451
452static const struct regmap_range_cfg spd5118_i2c_regmap_range_cfg[] = {
453 {
454 .selector_reg = SPD5118_REG_I2C_LEGACY_MODE,
455 .selector_mask = SPD5118_LEGACY_PAGE_MASK,
456 .selector_shift = 0,
457 .window_start = 0,
458 .window_len = 0x100,
459 .range_min = 0,
460 .range_max = 0x7ff,
461 },
462};
463
464static const struct regmap_config spd5118_regmap8_config = {
465 .reg_bits = 8,
466 .val_bits = 8,
467 .max_register = 0x7ff,
468 .writeable_reg = spd5118_writeable_reg,
469 .volatile_reg = spd5118_volatile_reg,
470 .cache_type = REGCACHE_MAPLE,
471
472 .ranges = spd5118_i2c_regmap_range_cfg,
473 .num_ranges = ARRAY_SIZE(spd5118_i2c_regmap_range_cfg),
474};
475
476static const struct regmap_config spd5118_regmap16_config = {
477 .reg_bits = 16,
478 .val_bits = 8,
479 .max_register = 0x7ff,
480 .writeable_reg = spd5118_writeable_reg,
481 .volatile_reg = spd5118_volatile_reg,
482 .cache_type = REGCACHE_MAPLE,
483};
484
485static int spd5118_suspend(struct device *dev)
486{
487 struct spd5118_data *data = dev_get_drvdata(dev);
488 struct regmap *regmap = data->regmap;
489 u32 regval;
490 int err;
491
492 /*
493 * Make sure the configuration register in the regmap cache is current
494 * before bypassing it.
495 */
496 err = regmap_read(map: regmap, SPD5118_REG_TEMP_CONFIG, val: &regval);
497 if (err < 0)
498 return err;
499
500 regcache_cache_bypass(map: regmap, enable: true);
501 regmap_update_bits(map: regmap, SPD5118_REG_TEMP_CONFIG, SPD5118_TS_DISABLE,
502 SPD5118_TS_DISABLE);
503 regcache_cache_bypass(map: regmap, enable: false);
504
505 regcache_cache_only(map: regmap, enable: true);
506 regcache_mark_dirty(map: regmap);
507
508 return 0;
509}
510
511static int spd5118_resume(struct device *dev)
512{
513 struct spd5118_data *data = dev_get_drvdata(dev);
514 struct regmap *regmap = data->regmap;
515
516 regcache_cache_only(map: regmap, enable: false);
517 return regcache_sync(map: regmap);
518}
519
520static DEFINE_SIMPLE_DEV_PM_OPS(spd5118_pm_ops, spd5118_suspend, spd5118_resume);
521
522static int spd5118_common_probe(struct device *dev, struct regmap *regmap,
523 bool is_16bit)
524{
525 unsigned int capability, revision, vendor, bank;
526 struct spd5118_data *data;
527 struct device *hwmon_dev;
528 int err;
529
530 data = devm_kzalloc(dev, size: sizeof(*data), GFP_KERNEL);
531 if (!data)
532 return -ENOMEM;
533
534 err = regmap_read(map: regmap, SPD5118_REG_CAPABILITY, val: &capability);
535 if (err)
536 return err;
537 if (!(capability & SPD5118_CAP_TS_SUPPORT))
538 return -ENODEV;
539
540 data->is_16bit = is_16bit;
541
542 err = regmap_read(map: regmap, SPD5118_REG_REVISION, val: &revision);
543 if (err)
544 return err;
545
546 err = regmap_read(map: regmap, SPD5118_REG_VENDOR, val: &bank);
547 if (err)
548 return err;
549 err = regmap_read(map: regmap, SPD5118_REG_VENDOR + 1, val: &vendor);
550 if (err)
551 return err;
552 if (!spd5118_vendor_valid(bank, id: vendor))
553 return -ENODEV;
554
555 data->regmap = regmap;
556 mutex_init(&data->nvmem_lock);
557 dev_set_drvdata(dev, data);
558
559 err = spd5118_nvmem_init(dev, data);
560 /* Ignore if NVMEM support is disabled */
561 if (err && err != -EOPNOTSUPP) {
562 dev_err_probe(dev, err, fmt: "failed to register nvmem\n");
563 return err;
564 }
565
566 hwmon_dev = devm_hwmon_device_register_with_info(dev, name: "spd5118",
567 drvdata: regmap, info: &spd5118_chip_info,
568 NULL);
569 if (IS_ERR(ptr: hwmon_dev))
570 return PTR_ERR(ptr: hwmon_dev);
571
572 /*
573 * From JESD300-5B
574 * MR2 bits [5:4]: Major revision, 1..4
575 * MR2 bits [3:1]: Minor revision, 0..8? Probably a typo, assume 1..8
576 */
577 dev_info(dev, "DDR5 temperature sensor: vendor 0x%02x:0x%02x revision %d.%d\n",
578 bank & 0x7f, vendor, ((revision >> 4) & 0x03) + 1, ((revision >> 1) & 0x07) + 1);
579
580 return 0;
581}
582
583/* I2C */
584
585/* Return 0 if detection is successful, -ENODEV otherwise */
586static int spd5118_detect(struct i2c_client *client, struct i2c_board_info *info)
587{
588 struct i2c_adapter *adapter = client->adapter;
589 int regval;
590
591 if (!i2c_check_functionality(adap: adapter, I2C_FUNC_SMBUS_BYTE_DATA |
592 I2C_FUNC_SMBUS_WORD_DATA))
593 return -ENODEV;
594
595 regval = i2c_smbus_read_word_swapped(client, SPD5118_REG_TYPE);
596 if (regval != 0x5118)
597 return -ENODEV;
598
599 regval = i2c_smbus_read_word_data(client, SPD5118_REG_VENDOR);
600 if (regval < 0 || !spd5118_vendor_valid(bank: regval & 0xff, id: regval >> 8))
601 return -ENODEV;
602
603 regval = i2c_smbus_read_byte_data(client, SPD5118_REG_CAPABILITY);
604 if (regval < 0)
605 return -ENODEV;
606 if (!(regval & SPD5118_CAP_TS_SUPPORT) || (regval & 0xfc))
607 return -ENODEV;
608
609 regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CLR);
610 if (regval)
611 return -ENODEV;
612 regval = i2c_smbus_read_byte_data(client, SPD5118_REG_ERROR_CLR);
613 if (regval)
614 return -ENODEV;
615
616 regval = i2c_smbus_read_byte_data(client, SPD5118_REG_REVISION);
617 if (regval < 0 || (regval & 0xc1))
618 return -ENODEV;
619
620 regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CONFIG);
621 if (regval < 0)
622 return -ENODEV;
623 if (regval & ~SPD5118_TS_DISABLE)
624 return -ENODEV;
625
626 strscpy(info->type, "spd5118", I2C_NAME_SIZE);
627 return 0;
628}
629
630static int spd5118_i2c_init(struct i2c_client *client)
631{
632 struct i2c_adapter *adapter = client->adapter;
633 int err, regval, mode;
634
635 if (!i2c_check_functionality(adap: adapter, I2C_FUNC_SMBUS_BYTE_DATA |
636 I2C_FUNC_SMBUS_WORD_DATA))
637 return -ENODEV;
638
639 regval = i2c_smbus_read_word_swapped(client, SPD5118_REG_TYPE);
640 if (regval < 0 || (regval && regval != 0x5118))
641 return -ENODEV;
642
643 /*
644 * If the device type registers return 0, it is possible that the chip
645 * has a non-zero page selected and takes the specification literally,
646 * i.e. disables access to volatile registers besides the page register
647 * if the page is not 0. The Renesas/ITD SPD5118 Hub Controller is known
648 * to show this behavior. Try to identify such chips.
649 */
650 if (!regval) {
651 /* Vendor ID registers must also be 0 */
652 regval = i2c_smbus_read_word_data(client, SPD5118_REG_VENDOR);
653 if (regval)
654 return -ENODEV;
655
656 /* The selected page in MR11 must not be 0 */
657 mode = i2c_smbus_read_byte_data(client, SPD5118_REG_I2C_LEGACY_MODE);
658 if (mode < 0 || (mode & ~SPD5118_LEGACY_MODE_MASK) ||
659 !(mode & SPD5118_LEGACY_PAGE_MASK))
660 return -ENODEV;
661
662 err = i2c_smbus_write_byte_data(client, SPD5118_REG_I2C_LEGACY_MODE,
663 value: mode & SPD5118_LEGACY_MODE_ADDR);
664 if (err)
665 return -ENODEV;
666
667 /*
668 * If the device type registers are still bad after selecting
669 * page 0, this is not a SPD5118 device. Restore original
670 * legacy mode register value and abort.
671 */
672 regval = i2c_smbus_read_word_swapped(client, SPD5118_REG_TYPE);
673 if (regval != 0x5118) {
674 i2c_smbus_write_byte_data(client, SPD5118_REG_I2C_LEGACY_MODE, value: mode);
675 return -ENODEV;
676 }
677 }
678
679 /* We are reasonably sure that this is really a SPD5118 hub controller */
680 return 0;
681}
682
683/*
684 * 16-bit addressing note:
685 *
686 * If I2C_FUNC_I2C is not supported by an I2C adapter driver, regmap uses
687 * SMBus operations as alternative. To simulate a read operation with a 16-bit
688 * address, it writes the address using i2c_smbus_write_byte_data(), followed
689 * by one or more calls to i2c_smbus_read_byte() to read the data.
690 * Per spd5118 standard, a read operation after writing the address must start
691 * with <Sr> (Repeat Start). However, a SMBus read byte operation starts with
692 * <S> (Start). This resets the register address in the spd5118 chip. As result,
693 * i2c_smbus_read_byte() always returns data from register address 0x00.
694 *
695 * A working alternative to access chips with 16-bit register addresses in the
696 * absence of I2C_FUNC_I2C support is not known.
697 *
698 * For this reason, 16-bit addressing can only be supported with I2C if the
699 * adapter supports I2C_FUNC_I2C.
700 *
701 * For I2C, the addressing mode selected by the BIOS must not be changed.
702 * Experiments show that at least some PC BIOS versions will not change the
703 * addressing mode on a soft reboot and end up in setup, claiming that some
704 * configuration change happened. This will happen again after a power cycle,
705 * which does reset the addressing mode. To prevent this from happening,
706 * detect if 16-bit addressing is enabled and always use the currently
707 * configured addressing mode.
708 */
709
710static int spd5118_i2c_probe(struct i2c_client *client)
711{
712 const struct regmap_config *config;
713 struct device *dev = &client->dev;
714 struct regmap *regmap;
715 int err, mode;
716 bool is_16bit;
717
718 err = spd5118_i2c_init(client);
719 if (err)
720 return err;
721
722 mode = i2c_smbus_read_byte_data(client, SPD5118_REG_I2C_LEGACY_MODE);
723 if (mode < 0)
724 return mode;
725
726 is_16bit = mode & SPD5118_LEGACY_MODE_ADDR;
727 if (is_16bit) {
728 /*
729 * See 16-bit addressing note above explaining why it is
730 * necessary to check for I2C_FUNC_I2C support here.
731 */
732 if (!i2c_check_functionality(adap: client->adapter, I2C_FUNC_I2C)) {
733 dev_err(dev, "Adapter does not support 16-bit register addresses\n");
734 return -ENODEV;
735 }
736 config = &spd5118_regmap16_config;
737 } else {
738 config = &spd5118_regmap8_config;
739 }
740
741 regmap = devm_regmap_init_i2c(client, config);
742 if (IS_ERR(ptr: regmap))
743 return dev_err_probe(dev, err: PTR_ERR(ptr: regmap), fmt: "regmap init failed\n");
744
745 return spd5118_common_probe(dev, regmap, is_16bit);
746}
747
748static const struct i2c_device_id spd5118_i2c_id[] = {
749 { "spd5118" },
750 { }
751};
752MODULE_DEVICE_TABLE(i2c, spd5118_i2c_id);
753
754static const struct of_device_id spd5118_of_ids[] = {
755 { .compatible = "jedec,spd5118", },
756 { }
757};
758MODULE_DEVICE_TABLE(of, spd5118_of_ids);
759
760static struct i2c_driver spd5118_i2c_driver = {
761 .class = I2C_CLASS_HWMON,
762 .driver = {
763 .name = "spd5118",
764 .of_match_table = spd5118_of_ids,
765 .pm = pm_sleep_ptr(&spd5118_pm_ops),
766 },
767 .probe = spd5118_i2c_probe,
768 .id_table = spd5118_i2c_id,
769 .detect = IS_ENABLED(CONFIG_SENSORS_SPD5118_DETECT) ? spd5118_detect : NULL,
770 .address_list = IS_ENABLED(CONFIG_SENSORS_SPD5118_DETECT) ? normal_i2c : NULL,
771};
772
773module_i2c_driver(spd5118_i2c_driver);
774
775MODULE_AUTHOR("René Rebe <rene@exactcode.de>");
776MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
777MODULE_DESCRIPTION("SPD 5118 driver");
778MODULE_LICENSE("GPL");
779

source code of linux/drivers/hwmon/spd5118.c