1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Driver for Linear Technology LTC4222 Dual 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/bitops.h>
13 #include <linux/i2c.h>
14 #include <linux/hwmon.h>
15 #include <linux/hwmon-sysfs.h>
16 #include <linux/jiffies.h>
17 #include <linux/regmap.h>
18 
19 /* chip registers */
20 
21 #define LTC4222_CONTROL1	0xd0
22 #define LTC4222_ALERT1		0xd1
23 #define LTC4222_STATUS1		0xd2
24 #define LTC4222_FAULT1		0xd3
25 #define LTC4222_CONTROL2	0xd4
26 #define LTC4222_ALERT2		0xd5
27 #define LTC4222_STATUS2		0xd6
28 #define LTC4222_FAULT2		0xd7
29 #define LTC4222_SOURCE1		0xd8
30 #define LTC4222_SOURCE2		0xda
31 #define LTC4222_ADIN1		0xdc
32 #define LTC4222_ADIN2		0xde
33 #define LTC4222_SENSE1		0xe0
34 #define LTC4222_SENSE2		0xe2
35 #define LTC4222_ADC_CONTROL	0xe4
36 
37 /*
38  * Fault register bits
39  */
40 #define FAULT_OV	BIT(0)
41 #define FAULT_UV	BIT(1)
42 #define FAULT_OC	BIT(2)
43 #define FAULT_POWER_BAD	BIT(3)
44 #define FAULT_FET_BAD	BIT(5)
45 
46 /* Return the voltage from the given register in mV or mA */
ltc4222_get_value(struct device * dev,u8 reg)47 static int ltc4222_get_value(struct device *dev, u8 reg)
48 {
49 	struct regmap *regmap = dev_get_drvdata(dev);
50 	unsigned int val;
51 	u8 buf[2];
52 	int ret;
53 
54 	ret = regmap_bulk_read(regmap, reg, buf, 2);
55 	if (ret < 0)
56 		return ret;
57 
58 	val = ((buf[0] << 8) + buf[1]) >> 6;
59 
60 	switch (reg) {
61 	case LTC4222_ADIN1:
62 	case LTC4222_ADIN2:
63 		/* 1.25 mV resolution. Convert to mV. */
64 		val = DIV_ROUND_CLOSEST(val * 5, 4);
65 		break;
66 	case LTC4222_SOURCE1:
67 	case LTC4222_SOURCE2:
68 		/* 31.25 mV resolution. Convert to mV. */
69 		val = DIV_ROUND_CLOSEST(val * 125, 4);
70 		break;
71 	case LTC4222_SENSE1:
72 	case LTC4222_SENSE2:
73 		/*
74 		 * 62.5 uV resolution. Convert to current as measured with
75 		 * an 1 mOhm sense resistor, in mA. If a different sense
76 		 * resistor is installed, calculate the actual current by
77 		 * dividing the reported current by the sense resistor value
78 		 * in mOhm.
79 		 */
80 		val = DIV_ROUND_CLOSEST(val * 125, 2);
81 		break;
82 	default:
83 		return -EINVAL;
84 	}
85 	return val;
86 }
87 
ltc4222_value_show(struct device * dev,struct device_attribute * da,char * buf)88 static ssize_t ltc4222_value_show(struct device *dev,
89 				  struct device_attribute *da, char *buf)
90 {
91 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
92 	int value;
93 
94 	value = ltc4222_get_value(dev, attr->index);
95 	if (value < 0)
96 		return value;
97 	return sysfs_emit(buf, "%d\n", value);
98 }
99 
ltc4222_bool_show(struct device * dev,struct device_attribute * da,char * buf)100 static ssize_t ltc4222_bool_show(struct device *dev,
101 				 struct device_attribute *da, char *buf)
102 {
103 	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
104 	struct regmap *regmap = dev_get_drvdata(dev);
105 	unsigned int fault;
106 	int ret;
107 
108 	ret = regmap_read(regmap, attr->nr, &fault);
109 	if (ret < 0)
110 		return ret;
111 	fault &= attr->index;
112 	if (fault)		/* Clear reported faults in chip register */
113 		regmap_update_bits(regmap, attr->nr, attr->index, 0);
114 
115 	return sysfs_emit(buf, "%d\n", !!fault);
116 }
117 
118 /* Voltages */
119 static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4222_value, LTC4222_SOURCE1);
120 static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4222_value, LTC4222_ADIN1);
121 static SENSOR_DEVICE_ATTR_RO(in3_input, ltc4222_value, LTC4222_SOURCE2);
122 static SENSOR_DEVICE_ATTR_RO(in4_input, ltc4222_value, LTC4222_ADIN2);
123 
124 /*
125  * Voltage alarms
126  * UV/OV faults are associated with the input voltage, and power bad and fet
127  * faults are associated with the output voltage.
128  */
129 static SENSOR_DEVICE_ATTR_2_RO(in1_min_alarm, ltc4222_bool, LTC4222_FAULT1,
130 			       FAULT_UV);
131 static SENSOR_DEVICE_ATTR_2_RO(in1_max_alarm, ltc4222_bool, LTC4222_FAULT1,
132 			       FAULT_OV);
133 static SENSOR_DEVICE_ATTR_2_RO(in2_alarm, ltc4222_bool, LTC4222_FAULT1,
134 			       FAULT_POWER_BAD | FAULT_FET_BAD);
135 
136 static SENSOR_DEVICE_ATTR_2_RO(in3_min_alarm, ltc4222_bool, LTC4222_FAULT2,
137 			       FAULT_UV);
138 static SENSOR_DEVICE_ATTR_2_RO(in3_max_alarm, ltc4222_bool, LTC4222_FAULT2,
139 			       FAULT_OV);
140 static SENSOR_DEVICE_ATTR_2_RO(in4_alarm, ltc4222_bool, LTC4222_FAULT2,
141 			       FAULT_POWER_BAD | FAULT_FET_BAD);
142 
143 /* Current (via sense resistor) */
144 static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4222_value, LTC4222_SENSE1);
145 static SENSOR_DEVICE_ATTR_RO(curr2_input, ltc4222_value, LTC4222_SENSE2);
146 
147 /* Overcurrent alarm */
148 static SENSOR_DEVICE_ATTR_2_RO(curr1_max_alarm, ltc4222_bool, LTC4222_FAULT1,
149 			       FAULT_OC);
150 static SENSOR_DEVICE_ATTR_2_RO(curr2_max_alarm, ltc4222_bool, LTC4222_FAULT2,
151 			       FAULT_OC);
152 
153 static struct attribute *ltc4222_attrs[] = {
154 	&sensor_dev_attr_in1_input.dev_attr.attr,
155 	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
156 	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
157 	&sensor_dev_attr_in2_input.dev_attr.attr,
158 	&sensor_dev_attr_in2_alarm.dev_attr.attr,
159 	&sensor_dev_attr_in3_input.dev_attr.attr,
160 	&sensor_dev_attr_in3_min_alarm.dev_attr.attr,
161 	&sensor_dev_attr_in3_max_alarm.dev_attr.attr,
162 	&sensor_dev_attr_in4_input.dev_attr.attr,
163 	&sensor_dev_attr_in4_alarm.dev_attr.attr,
164 
165 	&sensor_dev_attr_curr1_input.dev_attr.attr,
166 	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
167 	&sensor_dev_attr_curr2_input.dev_attr.attr,
168 	&sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
169 
170 	NULL,
171 };
172 ATTRIBUTE_GROUPS(ltc4222);
173 
174 static const struct regmap_config ltc4222_regmap_config = {
175 	.reg_bits = 8,
176 	.val_bits = 8,
177 	.max_register = LTC4222_ADC_CONTROL,
178 };
179 
ltc4222_probe(struct i2c_client * client)180 static int ltc4222_probe(struct i2c_client *client)
181 {
182 	struct device *dev = &client->dev;
183 	struct device *hwmon_dev;
184 	struct regmap *regmap;
185 
186 	regmap = devm_regmap_init_i2c(client, &ltc4222_regmap_config);
187 	if (IS_ERR(regmap)) {
188 		dev_err(dev, "failed to allocate register map\n");
189 		return PTR_ERR(regmap);
190 	}
191 
192 	/* Clear faults */
193 	regmap_write(regmap, LTC4222_FAULT1, 0x00);
194 	regmap_write(regmap, LTC4222_FAULT2, 0x00);
195 
196 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
197 							   regmap,
198 							   ltc4222_groups);
199 	return PTR_ERR_OR_ZERO(hwmon_dev);
200 }
201 
202 static const struct i2c_device_id ltc4222_id[] = {
203 	{"ltc4222", 0},
204 	{ }
205 };
206 
207 MODULE_DEVICE_TABLE(i2c, ltc4222_id);
208 
209 static struct i2c_driver ltc4222_driver = {
210 	.driver = {
211 		   .name = "ltc4222",
212 		   },
213 	.probe_new = ltc4222_probe,
214 	.id_table = ltc4222_id,
215 };
216 
217 module_i2c_driver(ltc4222_driver);
218 
219 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
220 MODULE_DESCRIPTION("LTC4222 driver");
221 MODULE_LICENSE("GPL");
222