1/*
2 * Driver for Linear Technology LTC4260 I2C Positive Voltage Hot Swap Controller
3 *
4 * Copyright (c) 2014 Guenter Roeck
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU General Public License for more details.
15 */
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/err.h>
20#include <linux/slab.h>
21#include <linux/i2c.h>
22#include <linux/hwmon.h>
23#include <linux/hwmon-sysfs.h>
24#include <linux/jiffies.h>
25#include <linux/regmap.h>
26
27/* chip registers */
28#define LTC4260_CONTROL	0x00
29#define LTC4260_ALERT	0x01
30#define LTC4260_STATUS	0x02
31#define LTC4260_FAULT	0x03
32#define LTC4260_SENSE	0x04
33#define LTC4260_SOURCE	0x05
34#define LTC4260_ADIN	0x06
35
36/*
37 * Fault register bits
38 */
39#define FAULT_OV	(1 << 0)
40#define FAULT_UV	(1 << 1)
41#define FAULT_OC	(1 << 2)
42#define FAULT_POWER_BAD	(1 << 3)
43#define FAULT_FET_SHORT	(1 << 5)
44
45/* Return the voltage from the given register in mV or mA */
46static int ltc4260_get_value(struct device *dev, u8 reg)
47{
48	struct regmap *regmap = dev_get_drvdata(dev);
49	unsigned int val;
50	int ret;
51
52	ret = regmap_read(regmap, reg, &val);
53	if (ret < 0)
54		return ret;
55
56	switch (reg) {
57	case LTC4260_ADIN:
58		/* 10 mV resolution. Convert to mV. */
59		val = val * 10;
60		break;
61	case LTC4260_SOURCE:
62		/* 400 mV resolution. Convert to mV. */
63		val = val * 400;
64		break;
65	case LTC4260_SENSE:
66		/*
67		 * 300 uV resolution. Convert to current as measured with
68		 * an 1 mOhm sense resistor, in mA. If a different sense
69		 * resistor is installed, calculate the actual current by
70		 * dividing the reported current by the sense resistor value
71		 * in mOhm.
72		 */
73		val = val * 300;
74		break;
75	default:
76		return -EINVAL;
77	}
78
79	return val;
80}
81
82static ssize_t ltc4260_show_value(struct device *dev,
83				  struct device_attribute *da, char *buf)
84{
85	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
86	int value;
87
88	value = ltc4260_get_value(dev, attr->index);
89	if (value < 0)
90		return value;
91	return snprintf(buf, PAGE_SIZE, "%d\n", value);
92}
93
94static ssize_t ltc4260_show_bool(struct device *dev,
95				 struct device_attribute *da, char *buf)
96{
97	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
98	struct regmap *regmap = dev_get_drvdata(dev);
99	unsigned int fault;
100	int ret;
101
102	ret = regmap_read(regmap, LTC4260_FAULT, &fault);
103	if (ret < 0)
104		return ret;
105
106	fault &= attr->index;
107	if (fault)		/* Clear reported faults in chip register */
108		regmap_update_bits(regmap, LTC4260_FAULT, attr->index, 0);
109
110	return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
111}
112
113/* Voltages */
114static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4260_show_value, NULL,
115			  LTC4260_SOURCE);
116static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4260_show_value, NULL,
117			  LTC4260_ADIN);
118
119/*
120 * Voltage alarms
121 * UV/OV faults are associated with the input voltage, and the POWER BAD and
122 * FET SHORT faults are associated with the output voltage.
123 */
124static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4260_show_bool, NULL,
125			  FAULT_UV);
126static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4260_show_bool, NULL,
127			  FAULT_OV);
128static SENSOR_DEVICE_ATTR(in2_alarm, S_IRUGO, ltc4260_show_bool, NULL,
129			  FAULT_POWER_BAD | FAULT_FET_SHORT);
130
131/* Current (via sense resistor) */
132static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4260_show_value, NULL,
133			  LTC4260_SENSE);
134
135/* Overcurrent alarm */
136static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4260_show_bool, NULL,
137			  FAULT_OC);
138
139static struct attribute *ltc4260_attrs[] = {
140	&sensor_dev_attr_in1_input.dev_attr.attr,
141	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
142	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
143	&sensor_dev_attr_in2_input.dev_attr.attr,
144	&sensor_dev_attr_in2_alarm.dev_attr.attr,
145
146	&sensor_dev_attr_curr1_input.dev_attr.attr,
147	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
148
149	NULL,
150};
151ATTRIBUTE_GROUPS(ltc4260);
152
153static const struct regmap_config ltc4260_regmap_config = {
154	.reg_bits = 8,
155	.val_bits = 8,
156	.max_register = LTC4260_ADIN,
157};
158
159static int ltc4260_probe(struct i2c_client *client,
160			 const struct i2c_device_id *id)
161{
162	struct device *dev = &client->dev;
163	struct device *hwmon_dev;
164	struct regmap *regmap;
165
166	regmap = devm_regmap_init_i2c(client, &ltc4260_regmap_config);
167	if (IS_ERR(regmap)) {
168		dev_err(dev, "failed to allocate register map\n");
169		return PTR_ERR(regmap);
170	}
171
172	/* Clear faults */
173	regmap_write(regmap, LTC4260_FAULT, 0x00);
174
175	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
176							   regmap,
177							   ltc4260_groups);
178	return PTR_ERR_OR_ZERO(hwmon_dev);
179}
180
181static const struct i2c_device_id ltc4260_id[] = {
182	{"ltc4260", 0},
183	{ }
184};
185
186MODULE_DEVICE_TABLE(i2c, ltc4260_id);
187
188static struct i2c_driver ltc4260_driver = {
189	.driver = {
190		   .name = "ltc4260",
191		   },
192	.probe = ltc4260_probe,
193	.id_table = ltc4260_id,
194};
195
196module_i2c_driver(ltc4260_driver);
197
198MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
199MODULE_DESCRIPTION("LTC4260 driver");
200MODULE_LICENSE("GPL");
201