xref: /linux/drivers/hwmon/ltc4260.c (revision 621cde16e49b3ecf7d59a8106a20aaebfb4a59a9)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Driver for Linear Technology LTC4260 I2C Positive Voltage Hot Swap Controller
4  *
5  * Copyright (c) 2014 Guenter Roeck
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/err.h>
11 #include <linux/slab.h>
12 #include <linux/i2c.h>
13 #include <linux/hwmon.h>
14 #include <linux/hwmon-sysfs.h>
15 #include <linux/jiffies.h>
16 #include <linux/regmap.h>
17 
18 /* chip registers */
19 #define LTC4260_CONTROL	0x00
20 #define LTC4260_ALERT	0x01
21 #define LTC4260_STATUS	0x02
22 #define LTC4260_FAULT	0x03
23 #define LTC4260_SENSE	0x04
24 #define LTC4260_SOURCE	0x05
25 #define LTC4260_ADIN	0x06
26 
27 /*
28  * Fault register bits
29  */
30 #define FAULT_OV	(1 << 0)
31 #define FAULT_UV	(1 << 1)
32 #define FAULT_OC	(1 << 2)
33 #define FAULT_POWER_BAD	(1 << 3)
34 #define FAULT_FET_SHORT	(1 << 5)
35 
36 /* Return the voltage from the given register in mV or mA */
ltc4260_get_value(struct device * dev,u8 reg)37 static int ltc4260_get_value(struct device *dev, u8 reg)
38 {
39 	struct regmap *regmap = dev_get_drvdata(dev);
40 	unsigned int val;
41 	int ret;
42 
43 	ret = regmap_read(regmap, reg, &val);
44 	if (ret < 0)
45 		return ret;
46 
47 	switch (reg) {
48 	case LTC4260_ADIN:
49 		/* 10 mV resolution. Convert to mV. */
50 		val = val * 10;
51 		break;
52 	case LTC4260_SOURCE:
53 		/* 400 mV resolution. Convert to mV. */
54 		val = val * 400;
55 		break;
56 	case LTC4260_SENSE:
57 		/*
58 		 * 300 uV resolution. Convert to current as measured with
59 		 * an 1 mOhm sense resistor, in mA. If a different sense
60 		 * resistor is installed, calculate the actual current by
61 		 * dividing the reported current by the sense resistor value
62 		 * in mOhm.
63 		 */
64 		val = val * 300;
65 		break;
66 	default:
67 		return -EINVAL;
68 	}
69 
70 	return val;
71 }
72 
ltc4260_value_show(struct device * dev,struct device_attribute * da,char * buf)73 static ssize_t ltc4260_value_show(struct device *dev,
74 				  struct device_attribute *da, char *buf)
75 {
76 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
77 	int value;
78 
79 	value = ltc4260_get_value(dev, attr->index);
80 	if (value < 0)
81 		return value;
82 	return sysfs_emit(buf, "%d\n", value);
83 }
84 
ltc4260_bool_show(struct device * dev,struct device_attribute * da,char * buf)85 static ssize_t ltc4260_bool_show(struct device *dev,
86 				 struct device_attribute *da, char *buf)
87 {
88 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
89 	struct regmap *regmap = dev_get_drvdata(dev);
90 	unsigned int fault;
91 	int ret;
92 
93 	ret = regmap_read(regmap, LTC4260_FAULT, &fault);
94 	if (ret < 0)
95 		return ret;
96 
97 	fault &= attr->index;
98 	if (fault)		/* Clear reported faults in chip register */
99 		regmap_update_bits(regmap, LTC4260_FAULT, attr->index, 0);
100 
101 	return sysfs_emit(buf, "%d\n", !!fault);
102 }
103 
104 /* Voltages */
105 static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4260_value, LTC4260_SOURCE);
106 static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4260_value, LTC4260_ADIN);
107 
108 /*
109  * Voltage alarms
110  * UV/OV faults are associated with the input voltage, and the POWER BAD and
111  * FET SHORT faults are associated with the output voltage.
112  */
113 static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4260_bool, FAULT_UV);
114 static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4260_bool, FAULT_OV);
115 static SENSOR_DEVICE_ATTR_RO(in2_alarm, ltc4260_bool,
116 			     FAULT_POWER_BAD | FAULT_FET_SHORT);
117 
118 /* Current (via sense resistor) */
119 static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4260_value, LTC4260_SENSE);
120 
121 /* Overcurrent alarm */
122 static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4260_bool, FAULT_OC);
123 
124 static struct attribute *ltc4260_attrs[] = {
125 	&sensor_dev_attr_in1_input.dev_attr.attr,
126 	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
127 	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
128 	&sensor_dev_attr_in2_input.dev_attr.attr,
129 	&sensor_dev_attr_in2_alarm.dev_attr.attr,
130 
131 	&sensor_dev_attr_curr1_input.dev_attr.attr,
132 	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
133 
134 	NULL,
135 };
136 ATTRIBUTE_GROUPS(ltc4260);
137 
138 static const struct regmap_config ltc4260_regmap_config = {
139 	.reg_bits = 8,
140 	.val_bits = 8,
141 	.max_register = LTC4260_ADIN,
142 };
143 
ltc4260_probe(struct i2c_client * client)144 static int ltc4260_probe(struct i2c_client *client)
145 {
146 	struct device *dev = &client->dev;
147 	struct device *hwmon_dev;
148 	struct regmap *regmap;
149 
150 	regmap = devm_regmap_init_i2c(client, &ltc4260_regmap_config);
151 	if (IS_ERR(regmap)) {
152 		dev_err(dev, "failed to allocate register map\n");
153 		return PTR_ERR(regmap);
154 	}
155 
156 	/* Clear faults */
157 	regmap_write(regmap, LTC4260_FAULT, 0x00);
158 
159 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
160 							   regmap,
161 							   ltc4260_groups);
162 	return PTR_ERR_OR_ZERO(hwmon_dev);
163 }
164 
165 static const struct i2c_device_id ltc4260_id[] = {
166 	{"ltc4260"},
167 	{ }
168 };
169 
170 MODULE_DEVICE_TABLE(i2c, ltc4260_id);
171 
172 static struct i2c_driver ltc4260_driver = {
173 	.driver = {
174 		   .name = "ltc4260",
175 		   },
176 	.probe = ltc4260_probe,
177 	.id_table = ltc4260_id,
178 };
179 
180 module_i2c_driver(ltc4260_driver);
181 
182 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
183 MODULE_DESCRIPTION("LTC4260 driver");
184 MODULE_LICENSE("GPL");
185