1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Hardware monitoring driver for Maxim MAX15301
4 *
5 * Copyright (c) 2021 Flextronics International Sweden AB
6 *
7 * Even though the specification does not specifically mention it,
8 * extensive empirical testing has revealed that auto-detection of
9 * limit-registers will fail in a random fashion unless the delay
10 * parameter is set to above about 80us. The default delay is set
11 * to 100us to include some safety margin.
12 */
13
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/init.h>
17#include <linux/err.h>
18#include <linux/slab.h>
19#include <linux/i2c.h>
20#include <linux/ktime.h>
21#include <linux/delay.h>
22#include <linux/pmbus.h>
23#include "pmbus.h"
24
25static const struct i2c_device_id max15301_id[] = {
26	{"bmr461", 0},
27	{"max15301", 0},
28	{}
29};
30MODULE_DEVICE_TABLE(i2c, max15301_id);
31
32struct max15301_data {
33	int id;
34	ktime_t access;		/* Chip access time */
35	int delay;		/* Delay between chip accesses in us */
36	struct pmbus_driver_info info;
37};
38
39#define to_max15301_data(x)  container_of(x, struct max15301_data, info)
40
41#define MAX15301_WAIT_TIME		100	/* us	*/
42
43static ushort delay = MAX15301_WAIT_TIME;
44module_param(delay, ushort, 0644);
45MODULE_PARM_DESC(delay, "Delay between chip accesses in us");
46
47static struct max15301_data max15301_data = {
48	.info = {
49		.pages = 1,
50		.func[0] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
51			| PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT
52			| PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2
53			| PMBUS_HAVE_STATUS_TEMP
54			| PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT,
55	}
56};
57
58/* This chip needs a delay between accesses */
59static inline void max15301_wait(const struct max15301_data *data)
60{
61	if (data->delay) {
62		s64 delta = ktime_us_delta(ktime_get(), data->access);
63
64		if (delta < data->delay)
65			udelay(data->delay - delta);
66	}
67}
68
69static int max15301_read_word_data(struct i2c_client *client, int page,
70				   int phase, int reg)
71{
72	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
73	struct max15301_data *data = to_max15301_data(info);
74	int ret;
75
76	if (page > 0)
77		return -ENXIO;
78
79	if (reg >= PMBUS_VIRT_BASE)
80		return -ENXIO;
81
82	max15301_wait(data);
83	ret = pmbus_read_word_data(client, page, phase, reg);
84	data->access = ktime_get();
85
86	return ret;
87}
88
89static int max15301_read_byte_data(struct i2c_client *client, int page, int reg)
90{
91	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
92	struct max15301_data *data = to_max15301_data(info);
93	int ret;
94
95	if (page > 0)
96		return -ENXIO;
97
98	max15301_wait(data);
99	ret = pmbus_read_byte_data(client, page, reg);
100	data->access = ktime_get();
101
102	return ret;
103}
104
105static int max15301_write_word_data(struct i2c_client *client, int page, int reg,
106				    u16 word)
107{
108	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
109	struct max15301_data *data = to_max15301_data(info);
110	int ret;
111
112	if (page > 0)
113		return -ENXIO;
114
115	if (reg >= PMBUS_VIRT_BASE)
116		return -ENXIO;
117
118	max15301_wait(data);
119	ret = pmbus_write_word_data(client, page, reg, word);
120	data->access = ktime_get();
121
122	return ret;
123}
124
125static int max15301_write_byte(struct i2c_client *client, int page, u8 value)
126{
127	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
128	struct max15301_data *data = to_max15301_data(info);
129	int ret;
130
131	if (page > 0)
132		return -ENXIO;
133
134	max15301_wait(data);
135	ret = pmbus_write_byte(client, page, value);
136	data->access = ktime_get();
137
138	return ret;
139}
140
141static int max15301_probe(struct i2c_client *client)
142{
143	int status;
144	u8 device_id[I2C_SMBUS_BLOCK_MAX + 1];
145	const struct i2c_device_id *mid;
146	struct pmbus_driver_info *info = &max15301_data.info;
147
148	if (!i2c_check_functionality(client->adapter,
149				     I2C_FUNC_SMBUS_READ_BYTE_DATA
150				     | I2C_FUNC_SMBUS_BLOCK_DATA))
151		return -ENODEV;
152
153	status = i2c_smbus_read_block_data(client, PMBUS_IC_DEVICE_ID, device_id);
154	if (status < 0) {
155		dev_err(&client->dev, "Failed to read Device Id\n");
156		return status;
157	}
158	for (mid = max15301_id; mid->name[0]; mid++) {
159		if (!strncasecmp(mid->name, device_id, strlen(mid->name)))
160			break;
161	}
162	if (!mid->name[0]) {
163		dev_err(&client->dev, "Unsupported device\n");
164		return -ENODEV;
165	}
166
167	max15301_data.delay = delay;
168
169	info->read_byte_data = max15301_read_byte_data;
170	info->read_word_data = max15301_read_word_data;
171	info->write_byte = max15301_write_byte;
172	info->write_word_data = max15301_write_word_data;
173
174	return pmbus_do_probe(client, info);
175}
176
177static struct i2c_driver max15301_driver = {
178	.driver = {
179		   .name = "max15301",
180		   },
181	.probe = max15301_probe,
182	.id_table = max15301_id,
183};
184
185module_i2c_driver(max15301_driver);
186
187MODULE_AUTHOR("Erik Rosen <erik.rosen@metormote.com>");
188MODULE_DESCRIPTION("PMBus driver for Maxim MAX15301");
189MODULE_LICENSE("GPL");
190MODULE_IMPORT_NS(PMBUS);
191