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
25 static const struct i2c_device_id max15301_id[] = {
26 {"bmr461", 0},
27 {"max15301", 0},
28 {}
29 };
30 MODULE_DEVICE_TABLE(i2c, max15301_id);
31
32 struct 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
43 static ushort delay = MAX15301_WAIT_TIME;
44 module_param(delay, ushort, 0644);
45 MODULE_PARM_DESC(delay, "Delay between chip accesses in us");
46
47 static 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 */
max15301_wait(const struct max15301_data * data)59 static 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
max15301_read_word_data(struct i2c_client * client,int page,int phase,int reg)69 static 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
max15301_read_byte_data(struct i2c_client * client,int page,int reg)89 static 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
max15301_write_word_data(struct i2c_client * client,int page,int reg,u16 word)105 static 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
max15301_write_byte(struct i2c_client * client,int page,u8 value)125 static 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
max15301_probe(struct i2c_client * client)141 static 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
177 static struct i2c_driver max15301_driver = {
178 .driver = {
179 .name = "max15301",
180 },
181 .probe = max15301_probe,
182 .id_table = max15301_id,
183 };
184
185 module_i2c_driver(max15301_driver);
186
187 MODULE_AUTHOR("Erik Rosen <erik.rosen@metormote.com>");
188 MODULE_DESCRIPTION("PMBus driver for Maxim MAX15301");
189 MODULE_LICENSE("GPL");
190 MODULE_IMPORT_NS(PMBUS);
191
