1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Hardware monitoring driver for Maxim MAX15301
5 * Copyright (c) 2021 Flextronics International Sweden AB
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.
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>
25 static const struct i2c_device_id max15301_id
[] = {
30 MODULE_DEVICE_TABLE(i2c
, max15301_id
);
32 struct max15301_data
{
34 ktime_t access
; /* Chip access time */
35 int delay
; /* Delay between chip accesses in us */
36 struct pmbus_driver_info info
;
39 #define to_max15301_data(x) container_of(x, struct max15301_data, info)
41 #define MAX15301_WAIT_TIME 100 /* us */
43 static ushort delay
= MAX15301_WAIT_TIME
;
44 module_param(delay
, ushort
, 0644);
45 MODULE_PARM_DESC(delay
, "Delay between chip accesses in us");
47 static struct max15301_data max15301_data
= {
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
,
58 /* This chip needs a delay between accesses */
59 static inline void max15301_wait(const struct max15301_data
*data
)
62 s64 delta
= ktime_us_delta(ktime_get(), data
->access
);
64 if (delta
< data
->delay
)
65 udelay(data
->delay
- delta
);
69 static int max15301_read_word_data(struct i2c_client
*client
, int page
,
72 const struct pmbus_driver_info
*info
= pmbus_get_driver_info(client
);
73 struct max15301_data
*data
= to_max15301_data(info
);
79 if (reg
>= PMBUS_VIRT_BASE
)
83 ret
= pmbus_read_word_data(client
, page
, phase
, reg
);
84 data
->access
= ktime_get();
89 static int max15301_read_byte_data(struct i2c_client
*client
, int page
, int reg
)
91 const struct pmbus_driver_info
*info
= pmbus_get_driver_info(client
);
92 struct max15301_data
*data
= to_max15301_data(info
);
99 ret
= pmbus_read_byte_data(client
, page
, reg
);
100 data
->access
= ktime_get();
105 static int max15301_write_word_data(struct i2c_client
*client
, int page
, int reg
,
108 const struct pmbus_driver_info
*info
= pmbus_get_driver_info(client
);
109 struct max15301_data
*data
= to_max15301_data(info
);
115 if (reg
>= PMBUS_VIRT_BASE
)
119 ret
= pmbus_write_word_data(client
, page
, reg
, word
);
120 data
->access
= ktime_get();
125 static int max15301_write_byte(struct i2c_client
*client
, int page
, u8 value
)
127 const struct pmbus_driver_info
*info
= pmbus_get_driver_info(client
);
128 struct max15301_data
*data
= to_max15301_data(info
);
135 ret
= pmbus_write_byte(client
, page
, value
);
136 data
->access
= ktime_get();
141 static int max15301_probe(struct i2c_client
*client
)
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
;
148 if (!i2c_check_functionality(client
->adapter
,
149 I2C_FUNC_SMBUS_READ_BYTE_DATA
150 | I2C_FUNC_SMBUS_BLOCK_DATA
))
153 status
= i2c_smbus_read_block_data(client
, PMBUS_IC_DEVICE_ID
, device_id
);
155 dev_err(&client
->dev
, "Failed to read Device Id\n");
158 for (mid
= max15301_id
; mid
->name
[0]; mid
++) {
159 if (!strncasecmp(mid
->name
, device_id
, strlen(mid
->name
)))
163 dev_err(&client
->dev
, "Unsupported device\n");
167 max15301_data
.delay
= delay
;
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
;
174 return pmbus_do_probe(client
, info
);
177 static struct i2c_driver max15301_driver
= {
181 .probe_new
= max15301_probe
,
182 .id_table
= max15301_id
,
185 module_i2c_driver(max15301_driver
);
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
);