1/*
2 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller
3 *
4 * Copyright (C) 2010 Ericsson AB.
5 *
6 * Derived from:
7 *
8 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
9 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
10 *
11 * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
22 *
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software
25 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 */
27
28#include <linux/kernel.h>
29#include <linux/module.h>
30#include <linux/init.h>
31#include <linux/err.h>
32#include <linux/slab.h>
33#include <linux/i2c.h>
34#include <linux/hwmon.h>
35#include <linux/hwmon-sysfs.h>
36#include <linux/jiffies.h>
37
38/* chip registers */
39#define LTC4261_STATUS 0x00 /* readonly */
40#define LTC4261_FAULT 0x01
41#define LTC4261_ALERT 0x02
42#define LTC4261_CONTROL 0x03
43#define LTC4261_SENSE_H 0x04
44#define LTC4261_SENSE_L 0x05
45#define LTC4261_ADIN2_H 0x06
46#define LTC4261_ADIN2_L 0x07
47#define LTC4261_ADIN_H 0x08
48#define LTC4261_ADIN_L 0x09
49
50/*
51 * Fault register bits
52 */
53#define FAULT_OV (1<<0)
54#define FAULT_UV (1<<1)
55#define FAULT_OC (1<<2)
56
57struct ltc4261_data {
58 struct i2c_client *client;
59
60 struct mutex update_lock;
61 bool valid;
62 unsigned long last_updated; /* in jiffies */
63
64 /* Registers */
65 u8 regs[10];
66};
67
68static struct ltc4261_data *ltc4261_update_device(struct device *dev)
69{
70 struct ltc4261_data *data = dev_get_drvdata(dev);
71 struct i2c_client *client = data->client;
72 struct ltc4261_data *ret = data;
73
74 mutex_lock(&data->update_lock);
75
76 if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) {
77 int i;
78
79 /* Read registers -- 0x00 to 0x09 */
80 for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
81 int val;
82
83 val = i2c_smbus_read_byte_data(client, i);
84 if (unlikely(val < 0)) {
85 dev_dbg(dev,
86 "Failed to read ADC value: error %d\n",
87 val);
88 ret = ERR_PTR(val);
89 data->valid = 0;
90 goto abort;
91 }
92 data->regs[i] = val;
93 }
94 data->last_updated = jiffies;
95 data->valid = 1;
96 }
97abort:
98 mutex_unlock(&data->update_lock);
99 return ret;
100}
101
102/* Return the voltage from the given register in mV or mA */
103static int ltc4261_get_value(struct ltc4261_data *data, u8 reg)
104{
105 u32 val;
106
107 val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6);
108
109 switch (reg) {
110 case LTC4261_ADIN_H:
111 case LTC4261_ADIN2_H:
112 /* 2.5mV resolution. Convert to mV. */
113 val = val * 25 / 10;
114 break;
115 case LTC4261_SENSE_H:
116 /*
117 * 62.5uV resolution. Convert to current as measured with
118 * an 1 mOhm sense resistor, in mA. If a different sense
119 * resistor is installed, calculate the actual current by
120 * dividing the reported current by the sense resistor value
121 * in mOhm.
122 */
123 val = val * 625 / 10;
124 break;
125 default:
126 /* If we get here, the developer messed up */
127 WARN_ON_ONCE(1);
128 val = 0;
129 break;
130 }
131
132 return val;
133}
134
135static ssize_t ltc4261_value_show(struct device *dev,
136 struct device_attribute *da, char *buf)
137{
138 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
139 struct ltc4261_data *data = ltc4261_update_device(dev);
140 int value;
141
142 if (IS_ERR(data))
143 return PTR_ERR(data);
144
145 value = ltc4261_get_value(data, attr->index);
146 return snprintf(buf, PAGE_SIZE, "%d\n", value);
147}
148
149static ssize_t ltc4261_bool_show(struct device *dev,
150 struct device_attribute *da, char *buf)
151{
152 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
153 struct ltc4261_data *data = ltc4261_update_device(dev);
154 u8 fault;
155
156 if (IS_ERR(data))
157 return PTR_ERR(data);
158
159 fault = data->regs[LTC4261_FAULT] & attr->index;
160 if (fault) /* Clear reported faults in chip register */
161 i2c_smbus_write_byte_data(data->client, LTC4261_FAULT, ~fault);
162
163 return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0);
164}
165
166/*
167 * Input voltages.
168 */
169static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4261_value, LTC4261_ADIN_H);
170static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4261_value, LTC4261_ADIN2_H);
171
172/*
173 * Voltage alarms. The chip has only one set of voltage alarm status bits,
174 * triggered by input voltage alarms. In many designs, those alarms are
175 * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
176 * to the OV pin. ADIN2 is, however, not available on all chip variants.
177 * To ensure that the alarm condition is reported to the user, report it
178 * with both voltage sensors.
179 */
180static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4261_bool, FAULT_UV);
181static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4261_bool, FAULT_OV);
182static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4261_bool, FAULT_UV);
183static SENSOR_DEVICE_ATTR_RO(in2_max_alarm, ltc4261_bool, FAULT_OV);
184
185/* Currents (via sense resistor) */
186static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4261_value, LTC4261_SENSE_H);
187
188/* Overcurrent alarm */
189static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4261_bool, FAULT_OC);
190
191static struct attribute *ltc4261_attrs[] = {
192 &sensor_dev_attr_in1_input.dev_attr.attr,
193 &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
194 &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
195 &sensor_dev_attr_in2_input.dev_attr.attr,
196 &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
197 &sensor_dev_attr_in2_max_alarm.dev_attr.attr,
198
199 &sensor_dev_attr_curr1_input.dev_attr.attr,
200 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
201
202 NULL,
203};
204ATTRIBUTE_GROUPS(ltc4261);
205
206static int ltc4261_probe(struct i2c_client *client,
207 const struct i2c_device_id *id)
208{
209 struct i2c_adapter *adapter = client->adapter;
210 struct device *dev = &client->dev;
211 struct ltc4261_data *data;
212 struct device *hwmon_dev;
213
214 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
215 return -ENODEV;
216
217 if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
218 dev_err(dev, "Failed to read status register\n");
219 return -ENODEV;
220 }
221
222 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
223 if (!data)
224 return -ENOMEM;
225
226 data->client = client;
227 mutex_init(&data->update_lock);
228
229 /* Clear faults */
230 i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);
231
232 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
233 data,
234 ltc4261_groups);
235 return PTR_ERR_OR_ZERO(hwmon_dev);
236}
237
238static const struct i2c_device_id ltc4261_id[] = {
239 {"ltc4261", 0},
240 {}
241};
242
243MODULE_DEVICE_TABLE(i2c, ltc4261_id);
244
245/* This is the driver that will be inserted */
246static struct i2c_driver ltc4261_driver = {
247 .driver = {
248 .name = "ltc4261",
249 },
250 .probe = ltc4261_probe,
251 .id_table = ltc4261_id,
252};
253
254module_i2c_driver(ltc4261_driver);
255
256MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
257MODULE_DESCRIPTION("LTC4261 driver");
258MODULE_LICENSE("GPL");
259