stpddc60.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Hardware monitoring driver for the STPDDC60 controller
  4 *
  5 * Copyright (c) 2021 Flextronics International Sweden AB.
  6 */
  7
  8#include <linux/kernel.h>
  9#include <linux/module.h>
 10#include <linux/init.h>
 11#include <linux/err.h>
 12#include <linux/i2c.h>
 13#include <linux/pmbus.h>
 14#include "pmbus.h"
 15
 16#define STPDDC60_MFR_READ_VOUT		0xd2
 17#define STPDDC60_MFR_OV_LIMIT_OFFSET	0xe5
 18#define STPDDC60_MFR_UV_LIMIT_OFFSET	0xe6
 19
 20static const struct i2c_device_id stpddc60_id[] = {
 21	{"stpddc60"},
 22	{"bmr481"},
 23	{}
 24};
 25MODULE_DEVICE_TABLE(i2c, stpddc60_id);
 26
 27static struct pmbus_driver_info stpddc60_info = {
 28	.pages = 1,
 29	.func[0] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
 30		| PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT
 31		| PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP
 32		| PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
 33		| PMBUS_HAVE_POUT,
 34};
 35
 36/*
 37 * Calculate the closest absolute offset between commanded vout value
 38 * and limit value in steps of 50mv in the range 0 (50mv) to 7 (400mv).
 39 * Return 0 if the upper limit is lower than vout or if the lower limit
 40 * is higher than vout.
 41 */
 42static u8 stpddc60_get_offset(int vout, u16 limit, bool over)
 43{
 44	int offset;
 45	long v, l;
 46
 47	v = 250 + (vout - 1) * 5; /* Convert VID to mv */
 48	l = (limit * 1000L) >> 8; /* Convert LINEAR to mv */
 49
 50	if (over == (l < v))
 51		return 0;
 52
 53	offset = DIV_ROUND_CLOSEST(abs(l - v), 50);
 54
 55	if (offset > 0)
 56		offset--;
 57
 58	return clamp_val(offset, 0, 7);
 59}
 60
 61/*
 62 * Adjust the linear format word to use the given fixed exponent.
 63 */
 64static u16 stpddc60_adjust_linear(u16 word, s16 fixed)
 65{
 66	s16 e, m, d;
 67
 68	e = ((s16)word) >> 11;
 69	m = ((s16)((word & 0x7ff) << 5)) >> 5;
 70	d = e - fixed;
 71
 72	if (d >= 0)
 73		m <<= d;
 74	else
 75		m >>= -d;
 76
 77	return clamp_val(m, 0, 0x3ff) | ((fixed << 11) & 0xf800);
 78}
 79
 80/*
 81 * The VOUT_COMMAND register uses the VID format but the vout alarm limit
 82 * registers use the LINEAR format so we override VOUT_MODE here to force
 83 * LINEAR format for all registers.
 84 */
 85static int stpddc60_read_byte_data(struct i2c_client *client, int page, int reg)
 86{
 87	int ret;
 88
 89	if (page > 0)
 90		return -ENXIO;
 91
 92	switch (reg) {
 93	case PMBUS_VOUT_MODE:
 94		ret = 0x18;
 95		break;
 96	default:
 97		ret = -ENODATA;
 98		break;
 99	}
100
101	return ret;
102}
103
104/*
105 * The vout related registers return values in LINEAR11 format when LINEAR16
106 * is expected. Clear the top 5 bits to set the exponent part to zero to
107 * convert the value to LINEAR16 format.
108 */
109static int stpddc60_read_word_data(struct i2c_client *client, int page,
110				   int phase, int reg)
111{
112	int ret;
113
114	if (page > 0)
115		return -ENXIO;
116
117	switch (reg) {
118	case PMBUS_READ_VOUT:
119		ret = pmbus_read_word_data(client, page, phase,
120					   STPDDC60_MFR_READ_VOUT);
121		if (ret < 0)
122			return ret;
123		ret &= 0x7ff;
124		break;
125	case PMBUS_VOUT_OV_FAULT_LIMIT:
126	case PMBUS_VOUT_UV_FAULT_LIMIT:
127		ret = pmbus_read_word_data(client, page, phase, reg);
128		if (ret < 0)
129			return ret;
130		ret &= 0x7ff;
131		break;
132	default:
133		ret = -ENODATA;
134		break;
135	}
136
137	return ret;
138}
139
140/*
141 * The vout under- and over-voltage limits are set as an offset relative to
142 * the commanded vout voltage. The vin, iout, pout and temp limits must use
143 * the same fixed exponent the chip uses to encode the data when read.
144 */
145static int stpddc60_write_word_data(struct i2c_client *client, int page,
146				    int reg, u16 word)
147{
148	int ret;
149	u8 offset;
150
151	if (page > 0)
152		return -ENXIO;
153
154	switch (reg) {
155	case PMBUS_VOUT_OV_FAULT_LIMIT:
156		ret = pmbus_read_word_data(client, page, 0xff,
157					   PMBUS_VOUT_COMMAND);
158		if (ret < 0)
159			return ret;
160		offset = stpddc60_get_offset(ret, word, true);
161		ret = pmbus_write_byte_data(client, page,
162					    STPDDC60_MFR_OV_LIMIT_OFFSET,
163					    offset);
164		break;
165	case PMBUS_VOUT_UV_FAULT_LIMIT:
166		ret = pmbus_read_word_data(client, page, 0xff,
167					   PMBUS_VOUT_COMMAND);
168		if (ret < 0)
169			return ret;
170		offset = stpddc60_get_offset(ret, word, false);
171		ret = pmbus_write_byte_data(client, page,
172					    STPDDC60_MFR_UV_LIMIT_OFFSET,
173					    offset);
174		break;
175	case PMBUS_VIN_OV_FAULT_LIMIT:
176	case PMBUS_VIN_UV_FAULT_LIMIT:
177	case PMBUS_OT_FAULT_LIMIT:
178	case PMBUS_OT_WARN_LIMIT:
179	case PMBUS_IOUT_OC_FAULT_LIMIT:
180	case PMBUS_IOUT_OC_WARN_LIMIT:
181	case PMBUS_POUT_OP_FAULT_LIMIT:
182		ret = pmbus_read_word_data(client, page, 0xff, reg);
183		if (ret < 0)
184			return ret;
185		word = stpddc60_adjust_linear(word, ret >> 11);
186		ret = pmbus_write_word_data(client, page, reg, word);
187		break;
188	default:
189		ret = -ENODATA;
190		break;
191	}
192
193	return ret;
194}
195
196static int stpddc60_probe(struct i2c_client *client)
197{
198	int status;
199	u8 device_id[I2C_SMBUS_BLOCK_MAX + 1];
200	const struct i2c_device_id *mid;
201	struct pmbus_driver_info *info = &stpddc60_info;
202
203	if (!i2c_check_functionality(client->adapter,
204				     I2C_FUNC_SMBUS_READ_BYTE_DATA
205				     | I2C_FUNC_SMBUS_BLOCK_DATA))
206		return -ENODEV;
207
208	status = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, device_id);
209	if (status < 0) {
210		dev_err(&client->dev, "Failed to read Manufacturer Model\n");
211		return status;
212	}
213	for (mid = stpddc60_id; mid->name[0]; mid++) {
214		if (!strncasecmp(mid->name, device_id, strlen(mid->name)))
215			break;
216	}
217	if (!mid->name[0]) {
218		dev_err(&client->dev, "Unsupported device\n");
219		return -ENODEV;
220	}
221
222	info->read_byte_data = stpddc60_read_byte_data;
223	info->read_word_data = stpddc60_read_word_data;
224	info->write_word_data = stpddc60_write_word_data;
225
226	status = pmbus_do_probe(client, info);
227	if (status < 0)
228		return status;
229
230	pmbus_set_update(client, PMBUS_VOUT_OV_FAULT_LIMIT, true);
231	pmbus_set_update(client, PMBUS_VOUT_UV_FAULT_LIMIT, true);
232
233	return 0;
234}
235
236static struct i2c_driver stpddc60_driver = {
237	.driver = {
238		   .name = "stpddc60",
239		   },
240	.probe = stpddc60_probe,
241	.id_table = stpddc60_id,
242};
243
244module_i2c_driver(stpddc60_driver);
245
246MODULE_AUTHOR("Erik Rosen <erik.rosen@metormote.com>");
247MODULE_DESCRIPTION("PMBus driver for ST STPDDC60");
248MODULE_LICENSE("GPL");
249MODULE_IMPORT_NS("PMBUS");