xref: /openbmc/linux/drivers/hwmon/pmbus/mp2975.c (revision 94d964e5)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers
4  *
5  * Copyright (C) 2020 Nvidia Technologies Ltd.
6  */
7 
8 #include <linux/err.h>
9 #include <linux/i2c.h>
10 #include <linux/init.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include "pmbus.h"
14 
15 /* Vendor specific registers. */
16 #define MP2975_MFR_APS_HYS_R2		0x0d
17 #define MP2975_MFR_SLOPE_TRIM3		0x1d
18 #define MP2975_MFR_VR_MULTI_CONFIG_R1	0x0d
19 #define MP2975_MFR_VR_MULTI_CONFIG_R2	0x1d
20 #define MP2975_MFR_APS_DECAY_ADV	0x56
21 #define MP2975_MFR_DC_LOOP_CTRL		0x59
22 #define MP2975_MFR_OCP_UCP_PHASE_SET	0x65
23 #define MP2975_MFR_VR_CONFIG1		0x68
24 #define MP2975_MFR_READ_CS1_2		0x82
25 #define MP2975_MFR_READ_CS3_4		0x83
26 #define MP2975_MFR_READ_CS5_6		0x84
27 #define MP2975_MFR_READ_CS7_8		0x85
28 #define MP2975_MFR_READ_CS9_10		0x86
29 #define MP2975_MFR_READ_CS11_12		0x87
30 #define MP2975_MFR_READ_IOUT_PK		0x90
31 #define MP2975_MFR_READ_POUT_PK		0x91
32 #define MP2975_MFR_READ_VREF_R1		0xa1
33 #define MP2975_MFR_READ_VREF_R2		0xa3
34 #define MP2975_MFR_OVP_TH_SET		0xe5
35 #define MP2975_MFR_UVP_SET		0xe6
36 
37 #define MP2975_VOUT_FORMAT		BIT(15)
38 #define MP2975_VID_STEP_SEL_R1		BIT(4)
39 #define MP2975_IMVP9_EN_R1		BIT(13)
40 #define MP2975_VID_STEP_SEL_R2		BIT(3)
41 #define MP2975_IMVP9_EN_R2		BIT(12)
42 #define MP2975_PRT_THRES_DIV_OV_EN	BIT(14)
43 #define MP2975_DRMOS_KCS		GENMASK(13, 12)
44 #define MP2975_PROT_DEV_OV_OFF		10
45 #define MP2975_PROT_DEV_OV_ON		5
46 #define MP2975_SENSE_AMPL		BIT(11)
47 #define MP2975_SENSE_AMPL_UNIT		1
48 #define MP2975_SENSE_AMPL_HALF		2
49 #define MP2975_VIN_UV_LIMIT_UNIT	8
50 
51 #define MP2975_MAX_PHASE_RAIL1	8
52 #define MP2975_MAX_PHASE_RAIL2	4
53 #define MP2975_PAGE_NUM		2
54 
55 #define MP2975_RAIL2_FUNC	(PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | \
56 				 PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT | \
57 				 PMBUS_HAVE_POUT | PMBUS_PHASE_VIRTUAL)
58 
59 struct mp2975_data {
60 	struct pmbus_driver_info info;
61 	int vout_scale;
62 	int vid_step[MP2975_PAGE_NUM];
63 	int vref[MP2975_PAGE_NUM];
64 	int vref_off[MP2975_PAGE_NUM];
65 	int vout_max[MP2975_PAGE_NUM];
66 	int vout_ov_fixed[MP2975_PAGE_NUM];
67 	int vout_format[MP2975_PAGE_NUM];
68 	int curr_sense_gain[MP2975_PAGE_NUM];
69 };
70 
71 #define to_mp2975_data(x)  container_of(x, struct mp2975_data, info)
72 
73 static int mp2975_read_byte_data(struct i2c_client *client, int page, int reg)
74 {
75 	switch (reg) {
76 	case PMBUS_VOUT_MODE:
77 		/*
78 		 * Enforce VOUT direct format, since device allows to set the
79 		 * different formats for the different rails. Conversion from
80 		 * VID to direct provided by driver internally, in case it is
81 		 * necessary.
82 		 */
83 		return PB_VOUT_MODE_DIRECT;
84 	default:
85 		return -ENODATA;
86 	}
87 }
88 
89 static int
90 mp2975_read_word_helper(struct i2c_client *client, int page, int phase, u8 reg,
91 			u16 mask)
92 {
93 	int ret = pmbus_read_word_data(client, page, phase, reg);
94 
95 	return (ret > 0) ? ret & mask : ret;
96 }
97 
98 static int
99 mp2975_vid2direct(int vrf, int val)
100 {
101 	switch (vrf) {
102 	case vr12:
103 		if (val >= 0x01)
104 			return 250 + (val - 1) * 5;
105 		break;
106 	case vr13:
107 		if (val >= 0x01)
108 			return 500 + (val - 1) * 10;
109 		break;
110 	case imvp9:
111 		if (val >= 0x01)
112 			return 200 + (val - 1) * 10;
113 		break;
114 	default:
115 		return -EINVAL;
116 	}
117 	return 0;
118 }
119 
120 static int
121 mp2975_read_phase(struct i2c_client *client, struct mp2975_data *data,
122 		  int page, int phase, u8 reg)
123 {
124 	int ph_curr, ret;
125 
126 	ret = pmbus_read_word_data(client, page, phase, reg);
127 	if (ret < 0)
128 		return ret;
129 
130 	if (!((phase + 1) % MP2975_PAGE_NUM))
131 		ret >>= 8;
132 	ret &= 0xff;
133 
134 	/*
135 	 * Output value is calculated as: (READ_CSx / 80 – 1.23) / (Kcs * Rcs)
136 	 * where:
137 	 * - Kcs is the DrMOS current sense gain of power stage, which is
138 	 *   obtained from the register MP2975_MFR_VR_CONFIG1, bits 13-12 with
139 	 *   the following selection of DrMOS (data->curr_sense_gain[page]):
140 	 *   00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A.
141 	 * - Rcs is the internal phase current sense resistor which is constant
142 	 *   value 1kΩ.
143 	 */
144 	ph_curr = ret * 100 - 9800;
145 
146 	/*
147 	 * Current phase sensing, providing by the device is not accurate
148 	 * for the light load. This because sampling of current occurrence of
149 	 * bit weight has a big deviation for light load. For handling such
150 	 * case phase current is represented as the maximum between the value
151 	 * calculated  above and total rail current divided by number phases.
152 	 */
153 	ret = pmbus_read_word_data(client, page, phase, PMBUS_READ_IOUT);
154 	if (ret < 0)
155 		return ret;
156 
157 	return max_t(int, DIV_ROUND_CLOSEST(ret, data->info.phases[page]),
158 		     DIV_ROUND_CLOSEST(ph_curr, data->curr_sense_gain[page]));
159 }
160 
161 static int
162 mp2975_read_phases(struct i2c_client *client, struct mp2975_data *data,
163 		   int page, int phase)
164 {
165 	int ret;
166 
167 	if (page) {
168 		switch (phase) {
169 		case 0 ... 1:
170 			ret = mp2975_read_phase(client, data, page, phase,
171 						MP2975_MFR_READ_CS7_8);
172 			break;
173 		case 2 ... 3:
174 			ret = mp2975_read_phase(client, data, page, phase,
175 						MP2975_MFR_READ_CS9_10);
176 			break;
177 		case 4 ... 5:
178 			ret = mp2975_read_phase(client, data, page, phase,
179 						MP2975_MFR_READ_CS11_12);
180 			break;
181 		default:
182 			return -ENODATA;
183 		}
184 	} else {
185 		switch (phase) {
186 		case 0 ... 1:
187 			ret = mp2975_read_phase(client, data, page, phase,
188 						MP2975_MFR_READ_CS1_2);
189 			break;
190 		case 2 ... 3:
191 			ret = mp2975_read_phase(client, data, page, phase,
192 						MP2975_MFR_READ_CS3_4);
193 			break;
194 		case 4 ... 5:
195 			ret = mp2975_read_phase(client, data, page, phase,
196 						MP2975_MFR_READ_CS5_6);
197 			break;
198 		case 6 ... 7:
199 			ret = mp2975_read_phase(client, data, page, phase,
200 						MP2975_MFR_READ_CS7_8);
201 			break;
202 		case 8 ... 9:
203 			ret = mp2975_read_phase(client, data, page, phase,
204 						MP2975_MFR_READ_CS9_10);
205 			break;
206 		case 10 ... 11:
207 			ret = mp2975_read_phase(client, data, page, phase,
208 						MP2975_MFR_READ_CS11_12);
209 			break;
210 		default:
211 			return -ENODATA;
212 		}
213 	}
214 	return ret;
215 }
216 
217 static int mp2975_read_word_data(struct i2c_client *client, int page,
218 				 int phase, int reg)
219 {
220 	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
221 	struct mp2975_data *data = to_mp2975_data(info);
222 	int ret;
223 
224 	switch (reg) {
225 	case PMBUS_OT_FAULT_LIMIT:
226 		ret = mp2975_read_word_helper(client, page, phase, reg,
227 					      GENMASK(7, 0));
228 		break;
229 	case PMBUS_VIN_OV_FAULT_LIMIT:
230 		ret = mp2975_read_word_helper(client, page, phase, reg,
231 					      GENMASK(7, 0));
232 		if (ret < 0)
233 			return ret;
234 
235 		ret = DIV_ROUND_CLOSEST(ret, MP2975_VIN_UV_LIMIT_UNIT);
236 		break;
237 	case PMBUS_VOUT_OV_FAULT_LIMIT:
238 		/*
239 		 * Register provides two values for over-voltage protection
240 		 * threshold for fixed (ovp2) and tracking (ovp1) modes. The
241 		 * minimum of these two values is provided as over-voltage
242 		 * fault alarm.
243 		 */
244 		ret = mp2975_read_word_helper(client, page, phase,
245 					      MP2975_MFR_OVP_TH_SET,
246 					      GENMASK(2, 0));
247 		if (ret < 0)
248 			return ret;
249 
250 		ret = min_t(int, data->vout_max[page] + 50 * (ret + 1),
251 			    data->vout_ov_fixed[page]);
252 		break;
253 	case PMBUS_VOUT_UV_FAULT_LIMIT:
254 		ret = mp2975_read_word_helper(client, page, phase,
255 					      MP2975_MFR_UVP_SET,
256 					      GENMASK(2, 0));
257 		if (ret < 0)
258 			return ret;
259 
260 		ret = DIV_ROUND_CLOSEST(data->vref[page] * 10 - 50 *
261 					(ret + 1) * data->vout_scale, 10);
262 		break;
263 	case PMBUS_READ_VOUT:
264 		ret = mp2975_read_word_helper(client, page, phase, reg,
265 					      GENMASK(11, 0));
266 		if (ret < 0)
267 			return ret;
268 
269 		/*
270 		 * READ_VOUT can be provided in VID or direct format. The
271 		 * format type is specified by bit 15 of the register
272 		 * MP2975_MFR_DC_LOOP_CTRL. The driver enforces VOUT direct
273 		 * format, since device allows to set the different formats for
274 		 * the different rails and also all VOUT limits registers are
275 		 * provided in a direct format. In case format is VID - convert
276 		 * to direct.
277 		 */
278 		if (data->vout_format[page] == vid)
279 			ret = mp2975_vid2direct(info->vrm_version[page], ret);
280 		break;
281 	case PMBUS_VIRT_READ_POUT_MAX:
282 		ret = mp2975_read_word_helper(client, page, phase,
283 					      MP2975_MFR_READ_POUT_PK,
284 					      GENMASK(12, 0));
285 		if (ret < 0)
286 			return ret;
287 
288 		ret = DIV_ROUND_CLOSEST(ret, 4);
289 		break;
290 	case PMBUS_VIRT_READ_IOUT_MAX:
291 		ret = mp2975_read_word_helper(client, page, phase,
292 					      MP2975_MFR_READ_IOUT_PK,
293 					      GENMASK(12, 0));
294 		if (ret < 0)
295 			return ret;
296 
297 		ret = DIV_ROUND_CLOSEST(ret, 4);
298 		break;
299 	case PMBUS_READ_IOUT:
300 		ret = mp2975_read_phases(client, data, page, phase);
301 		if (ret < 0)
302 			return ret;
303 
304 		break;
305 	case PMBUS_UT_WARN_LIMIT:
306 	case PMBUS_UT_FAULT_LIMIT:
307 	case PMBUS_VIN_UV_WARN_LIMIT:
308 	case PMBUS_VIN_UV_FAULT_LIMIT:
309 	case PMBUS_VOUT_UV_WARN_LIMIT:
310 	case PMBUS_VOUT_OV_WARN_LIMIT:
311 	case PMBUS_VIN_OV_WARN_LIMIT:
312 	case PMBUS_IIN_OC_FAULT_LIMIT:
313 	case PMBUS_IOUT_OC_LV_FAULT_LIMIT:
314 	case PMBUS_IIN_OC_WARN_LIMIT:
315 	case PMBUS_IOUT_OC_WARN_LIMIT:
316 	case PMBUS_IOUT_OC_FAULT_LIMIT:
317 	case PMBUS_IOUT_UC_FAULT_LIMIT:
318 	case PMBUS_POUT_OP_FAULT_LIMIT:
319 	case PMBUS_POUT_OP_WARN_LIMIT:
320 	case PMBUS_PIN_OP_WARN_LIMIT:
321 		return -ENXIO;
322 	default:
323 		return -ENODATA;
324 	}
325 
326 	return ret;
327 }
328 
329 static int mp2975_identify_multiphase_rail2(struct i2c_client *client)
330 {
331 	int ret;
332 
333 	/*
334 	 * Identify multiphase for rail 2 - could be from 0 to 4.
335 	 * In case phase number is zero – only page zero is supported
336 	 */
337 	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
338 	if (ret < 0)
339 		return ret;
340 
341 	/* Identify multiphase for rail 2 - could be from 0 to 4. */
342 	ret = i2c_smbus_read_word_data(client, MP2975_MFR_VR_MULTI_CONFIG_R2);
343 	if (ret < 0)
344 		return ret;
345 
346 	ret &= GENMASK(2, 0);
347 	return (ret >= 4) ? 4 : ret;
348 }
349 
350 static void mp2975_set_phase_rail1(struct pmbus_driver_info *info)
351 {
352 	int i;
353 
354 	for (i = 0 ; i < info->phases[0]; i++)
355 		info->pfunc[i] = PMBUS_HAVE_IOUT;
356 }
357 
358 static void
359 mp2975_set_phase_rail2(struct pmbus_driver_info *info, int num_phases)
360 {
361 	int i;
362 
363 	/* Set phases for rail 2 from upper to lower. */
364 	for (i = 1; i <= num_phases; i++)
365 		info->pfunc[MP2975_MAX_PHASE_RAIL1 - i] = PMBUS_HAVE_IOUT;
366 }
367 
368 static int
369 mp2975_identify_multiphase(struct i2c_client *client, struct mp2975_data *data,
370 			   struct pmbus_driver_info *info)
371 {
372 	int num_phases2, ret;
373 
374 	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
375 	if (ret < 0)
376 		return ret;
377 
378 	/* Identify multiphase for rail 1 - could be from 1 to 8. */
379 	ret = i2c_smbus_read_word_data(client, MP2975_MFR_VR_MULTI_CONFIG_R1);
380 	if (ret <= 0)
381 		return ret;
382 
383 	info->phases[0] = ret & GENMASK(3, 0);
384 
385 	/*
386 	 * The device provides a total of 8 PWM pins, and can be configured
387 	 * to different phase count applications for rail 1 and rail 2.
388 	 * Rail 1 can be set to 8 phases, while rail 2 can only be set to 4
389 	 * phases at most. When rail 1’s phase count is configured as 0, rail
390 	 * 1 operates with 1-phase DCM. When rail 2 phase count is configured
391 	 * as 0, rail 2 is disabled.
392 	 */
393 	if (info->phases[0] > MP2975_MAX_PHASE_RAIL1)
394 		return -EINVAL;
395 
396 	mp2975_set_phase_rail1(info);
397 	num_phases2 = min(MP2975_MAX_PHASE_RAIL1 - info->phases[0],
398 			  MP2975_MAX_PHASE_RAIL2);
399 	if (info->phases[1] && info->phases[1] <= num_phases2)
400 		mp2975_set_phase_rail2(info, num_phases2);
401 
402 	return 0;
403 }
404 
405 static int
406 mp2975_identify_vid(struct i2c_client *client, struct mp2975_data *data,
407 		    struct pmbus_driver_info *info, u32 reg, int page,
408 		    u32 imvp_bit, u32 vr_bit)
409 {
410 	int ret;
411 
412 	/* Identify VID mode and step selection. */
413 	ret = i2c_smbus_read_word_data(client, reg);
414 	if (ret < 0)
415 		return ret;
416 
417 	if (ret & imvp_bit) {
418 		info->vrm_version[page] = imvp9;
419 		data->vid_step[page] = MP2975_PROT_DEV_OV_OFF;
420 	} else if (ret & vr_bit) {
421 		info->vrm_version[page] = vr12;
422 		data->vid_step[page] = MP2975_PROT_DEV_OV_ON;
423 	} else {
424 		info->vrm_version[page] = vr13;
425 		data->vid_step[page] = MP2975_PROT_DEV_OV_OFF;
426 	}
427 
428 	return 0;
429 }
430 
431 static int
432 mp2975_identify_rails_vid(struct i2c_client *client, struct mp2975_data *data,
433 			  struct pmbus_driver_info *info)
434 {
435 	int ret;
436 
437 	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
438 	if (ret < 0)
439 		return ret;
440 
441 	/* Identify VID mode for rail 1. */
442 	ret = mp2975_identify_vid(client, data, info,
443 				  MP2975_MFR_VR_MULTI_CONFIG_R1, 0,
444 				  MP2975_IMVP9_EN_R1, MP2975_VID_STEP_SEL_R1);
445 	if (ret < 0)
446 		return ret;
447 
448 	/* Identify VID mode for rail 2, if connected. */
449 	if (info->phases[1])
450 		ret = mp2975_identify_vid(client, data, info,
451 					  MP2975_MFR_VR_MULTI_CONFIG_R2, 1,
452 					  MP2975_IMVP9_EN_R2,
453 					  MP2975_VID_STEP_SEL_R2);
454 	return ret;
455 }
456 
457 static int
458 mp2975_current_sense_gain_get(struct i2c_client *client,
459 			      struct mp2975_data *data)
460 {
461 	int i, ret;
462 
463 	/*
464 	 * Obtain DrMOS current sense gain of power stage from the register
465 	 * MP2975_MFR_VR_CONFIG1, bits 13-12. The value is selected as below:
466 	 * 00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A. Other
467 	 * values are invalid.
468 	 */
469 	for (i = 0 ; i < data->info.pages; i++) {
470 		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
471 		if (ret < 0)
472 			return ret;
473 		ret = i2c_smbus_read_word_data(client,
474 					       MP2975_MFR_VR_CONFIG1);
475 		if (ret < 0)
476 			return ret;
477 
478 		switch ((ret & MP2975_DRMOS_KCS) >> 12) {
479 		case 0:
480 			data->curr_sense_gain[i] = 50;
481 			break;
482 		case 1:
483 			data->curr_sense_gain[i] = 85;
484 			break;
485 		case 2:
486 			data->curr_sense_gain[i] = 97;
487 			break;
488 		default:
489 			data->curr_sense_gain[i] = 100;
490 			break;
491 		}
492 	}
493 
494 	return 0;
495 }
496 
497 static int
498 mp2975_vref_get(struct i2c_client *client, struct mp2975_data *data,
499 		struct pmbus_driver_info *info)
500 {
501 	int ret;
502 
503 	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 3);
504 	if (ret < 0)
505 		return ret;
506 
507 	/* Get voltage reference value for rail 1. */
508 	ret = i2c_smbus_read_word_data(client, MP2975_MFR_READ_VREF_R1);
509 	if (ret < 0)
510 		return ret;
511 
512 	data->vref[0] = ret * data->vid_step[0];
513 
514 	/* Get voltage reference value for rail 2, if connected. */
515 	if (data->info.pages == MP2975_PAGE_NUM) {
516 		ret = i2c_smbus_read_word_data(client, MP2975_MFR_READ_VREF_R2);
517 		if (ret < 0)
518 			return ret;
519 
520 		data->vref[1] = ret * data->vid_step[1];
521 	}
522 	return 0;
523 }
524 
525 static int
526 mp2975_vref_offset_get(struct i2c_client *client, struct mp2975_data *data,
527 		       int page)
528 {
529 	int ret;
530 
531 	ret = i2c_smbus_read_word_data(client, MP2975_MFR_OVP_TH_SET);
532 	if (ret < 0)
533 		return ret;
534 
535 	switch ((ret & GENMASK(5, 3)) >> 3) {
536 	case 1:
537 		data->vref_off[page] = 140;
538 		break;
539 	case 2:
540 		data->vref_off[page] = 220;
541 		break;
542 	case 4:
543 		data->vref_off[page] = 400;
544 		break;
545 	default:
546 		return -EINVAL;
547 	}
548 	return 0;
549 }
550 
551 static int
552 mp2975_vout_max_get(struct i2c_client *client, struct mp2975_data *data,
553 		    struct pmbus_driver_info *info, int page)
554 {
555 	int ret;
556 
557 	/* Get maximum reference voltage of VID-DAC in VID format. */
558 	ret = i2c_smbus_read_word_data(client, PMBUS_VOUT_MAX);
559 	if (ret < 0)
560 		return ret;
561 
562 	data->vout_max[page] = mp2975_vid2direct(info->vrm_version[page], ret &
563 						 GENMASK(8, 0));
564 	return 0;
565 }
566 
567 static int
568 mp2975_identify_vout_format(struct i2c_client *client,
569 			    struct mp2975_data *data, int page)
570 {
571 	int ret;
572 
573 	ret = i2c_smbus_read_word_data(client, MP2975_MFR_DC_LOOP_CTRL);
574 	if (ret < 0)
575 		return ret;
576 
577 	if (ret & MP2975_VOUT_FORMAT)
578 		data->vout_format[page] = vid;
579 	else
580 		data->vout_format[page] = direct;
581 	return 0;
582 }
583 
584 static int
585 mp2975_vout_ov_scale_get(struct i2c_client *client, struct mp2975_data *data,
586 			 struct pmbus_driver_info *info)
587 {
588 	int thres_dev, sense_ampl, ret;
589 
590 	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
591 	if (ret < 0)
592 		return ret;
593 
594 	/*
595 	 * Get divider for over- and under-voltage protection thresholds
596 	 * configuration from the Advanced Options of Auto Phase Shedding and
597 	 * decay register.
598 	 */
599 	ret = i2c_smbus_read_word_data(client, MP2975_MFR_APS_DECAY_ADV);
600 	if (ret < 0)
601 		return ret;
602 	thres_dev = ret & MP2975_PRT_THRES_DIV_OV_EN ? MP2975_PROT_DEV_OV_ON :
603 	                                               MP2975_PROT_DEV_OV_OFF;
604 
605 	/* Select the gain of remote sense amplifier. */
606 	ret = i2c_smbus_read_word_data(client, PMBUS_VOUT_SCALE_LOOP);
607 	if (ret < 0)
608 		return ret;
609 	sense_ampl = ret & MP2975_SENSE_AMPL ? MP2975_SENSE_AMPL_HALF :
610 					       MP2975_SENSE_AMPL_UNIT;
611 
612 	data->vout_scale = sense_ampl * thres_dev;
613 
614 	return 0;
615 }
616 
617 static int
618 mp2975_vout_per_rail_config_get(struct i2c_client *client,
619 				struct mp2975_data *data,
620 				struct pmbus_driver_info *info)
621 {
622 	int i, ret;
623 
624 	for (i = 0; i < data->info.pages; i++) {
625 		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
626 		if (ret < 0)
627 			return ret;
628 
629 		/* Obtain voltage reference offsets. */
630 		ret = mp2975_vref_offset_get(client, data, i);
631 		if (ret < 0)
632 			return ret;
633 
634 		/* Obtain maximum voltage values. */
635 		ret = mp2975_vout_max_get(client, data, info, i);
636 		if (ret < 0)
637 			return ret;
638 
639 		/*
640 		 * Get VOUT format for READ_VOUT command : VID or direct.
641 		 * Pages on same device can be configured with different
642 		 * formats.
643 		 */
644 		ret = mp2975_identify_vout_format(client, data, i);
645 		if (ret < 0)
646 			return ret;
647 
648 		/*
649 		 * Set over-voltage fixed value. Thresholds are provided as
650 		 * fixed value, and tracking value. The minimum of them are
651 		 * exposed as over-voltage critical threshold.
652 		 */
653 		data->vout_ov_fixed[i] = data->vref[i] +
654 					 DIV_ROUND_CLOSEST(data->vref_off[i] *
655 							   data->vout_scale,
656 							   10);
657 	}
658 
659 	return 0;
660 }
661 
662 static struct pmbus_driver_info mp2975_info = {
663 	.pages = 1,
664 	.format[PSC_VOLTAGE_IN] = linear,
665 	.format[PSC_VOLTAGE_OUT] = direct,
666 	.format[PSC_TEMPERATURE] = direct,
667 	.format[PSC_CURRENT_IN] = linear,
668 	.format[PSC_CURRENT_OUT] = direct,
669 	.format[PSC_POWER] = direct,
670 	.m[PSC_TEMPERATURE] = 1,
671 	.m[PSC_VOLTAGE_OUT] = 1,
672 	.R[PSC_VOLTAGE_OUT] = 3,
673 	.m[PSC_CURRENT_OUT] = 1,
674 	.m[PSC_POWER] = 1,
675 	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
676 		PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
677 		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_POUT |
678 		PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT | PMBUS_PHASE_VIRTUAL,
679 	.read_byte_data = mp2975_read_byte_data,
680 	.read_word_data = mp2975_read_word_data,
681 };
682 
683 static int mp2975_probe(struct i2c_client *client)
684 {
685 	struct pmbus_driver_info *info;
686 	struct mp2975_data *data;
687 	int ret;
688 
689 	data = devm_kzalloc(&client->dev, sizeof(struct mp2975_data),
690 			    GFP_KERNEL);
691 	if (!data)
692 		return -ENOMEM;
693 
694 	memcpy(&data->info, &mp2975_info, sizeof(*info));
695 	info = &data->info;
696 
697 	/* Identify multiphase configuration for rail 2. */
698 	ret = mp2975_identify_multiphase_rail2(client);
699 	if (ret < 0)
700 		return ret;
701 
702 	if (ret) {
703 		/* Two rails are connected. */
704 		data->info.pages = MP2975_PAGE_NUM;
705 		data->info.phases[1] = ret;
706 		data->info.func[1] = MP2975_RAIL2_FUNC;
707 	}
708 
709 	/* Identify multiphase configuration. */
710 	ret = mp2975_identify_multiphase(client, data, info);
711 	if (ret)
712 		return ret;
713 
714 	/* Identify VID setting per rail. */
715 	ret = mp2975_identify_rails_vid(client, data, info);
716 	if (ret < 0)
717 		return ret;
718 
719 	/* Obtain current sense gain of power stage. */
720 	ret = mp2975_current_sense_gain_get(client, data);
721 	if (ret)
722 		return ret;
723 
724 	/* Obtain voltage reference values. */
725 	ret = mp2975_vref_get(client, data, info);
726 	if (ret)
727 		return ret;
728 
729 	/* Obtain vout over-voltage scales. */
730 	ret = mp2975_vout_ov_scale_get(client, data, info);
731 	if (ret < 0)
732 		return ret;
733 
734 	/* Obtain offsets, maximum and format for vout. */
735 	ret = mp2975_vout_per_rail_config_get(client, data, info);
736 	if (ret)
737 		return ret;
738 
739 	return pmbus_do_probe(client, info);
740 }
741 
742 static const struct i2c_device_id mp2975_id[] = {
743 	{"mp2975", 0},
744 	{}
745 };
746 
747 MODULE_DEVICE_TABLE(i2c, mp2975_id);
748 
749 static const struct of_device_id __maybe_unused mp2975_of_match[] = {
750 	{.compatible = "mps,mp2975"},
751 	{}
752 };
753 MODULE_DEVICE_TABLE(of, mp2975_of_match);
754 
755 static struct i2c_driver mp2975_driver = {
756 	.driver = {
757 		.name = "mp2975",
758 		.of_match_table = of_match_ptr(mp2975_of_match),
759 	},
760 	.probe_new = mp2975_probe,
761 	.id_table = mp2975_id,
762 };
763 
764 module_i2c_driver(mp2975_driver);
765 
766 MODULE_AUTHOR("Vadim Pasternak <vadimp@nvidia.com>");
767 MODULE_DESCRIPTION("PMBus driver for MPS MP2975 device");
768 MODULE_LICENSE("GPL");
769 MODULE_IMPORT_NS(PMBUS);
770