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Ira Snyder72f5de92009-03-31 15:24:29 -07001/*
2 * Driver for Linear Technology LTC4215 I2C Hot Swap Controller
3 *
4 * Copyright (C) 2009 Ira W. Snyder <iws@ovro.caltech.edu>
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; version 2 of the License.
9 *
10 * Datasheet:
11 * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697
12 */
13
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/hwmon.h>
21#include <linux/hwmon-sysfs.h>
22
Ira Snyder72f5de92009-03-31 15:24:29 -070023/* Here are names of the chip's registers (a.k.a. commands) */
24enum ltc4215_cmd {
25 LTC4215_CONTROL = 0x00, /* rw */
26 LTC4215_ALERT = 0x01, /* rw */
27 LTC4215_STATUS = 0x02, /* ro */
28 LTC4215_FAULT = 0x03, /* rw */
29 LTC4215_SENSE = 0x04, /* rw */
30 LTC4215_SOURCE = 0x05, /* rw */
31 LTC4215_ADIN = 0x06, /* rw */
32};
33
34struct ltc4215_data {
35 struct device *hwmon_dev;
36
37 struct mutex update_lock;
38 bool valid;
39 unsigned long last_updated; /* in jiffies */
40
41 /* Registers */
42 u8 regs[7];
43};
44
45static struct ltc4215_data *ltc4215_update_device(struct device *dev)
46{
47 struct i2c_client *client = to_i2c_client(dev);
48 struct ltc4215_data *data = i2c_get_clientdata(client);
49 s32 val;
50 int i;
51
52 mutex_lock(&data->update_lock);
53
54 /* The chip's A/D updates 10 times per second */
55 if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
56
57 dev_dbg(&client->dev, "Starting ltc4215 update\n");
58
59 /* Read all registers */
60 for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
61 val = i2c_smbus_read_byte_data(client, i);
62 if (unlikely(val < 0))
63 data->regs[i] = 0;
64 else
65 data->regs[i] = val;
66 }
67
68 data->last_updated = jiffies;
69 data->valid = 1;
70 }
71
72 mutex_unlock(&data->update_lock);
73
74 return data;
75}
76
77/* Return the voltage from the given register in millivolts */
78static int ltc4215_get_voltage(struct device *dev, u8 reg)
79{
80 struct ltc4215_data *data = ltc4215_update_device(dev);
81 const u8 regval = data->regs[reg];
82 u32 voltage = 0;
83
84 switch (reg) {
85 case LTC4215_SENSE:
86 /* 151 uV per increment */
87 voltage = regval * 151 / 1000;
88 break;
89 case LTC4215_SOURCE:
90 /* 60.5 mV per increment */
91 voltage = regval * 605 / 10;
92 break;
93 case LTC4215_ADIN:
Guenter Roeck790fa382012-01-19 11:02:21 -080094 /*
95 * The ADIN input is divided by 12.5, and has 4.82 mV
96 * per increment, so we have the additional multiply
97 */
Ira Snyder72f5de92009-03-31 15:24:29 -070098 voltage = regval * 482 * 125 / 1000;
99 break;
100 default:
101 /* If we get here, the developer messed up */
102 WARN_ON_ONCE(1);
103 break;
104 }
105
106 return voltage;
107}
108
109/* Return the current from the sense resistor in mA */
110static unsigned int ltc4215_get_current(struct device *dev)
111{
112 struct ltc4215_data *data = ltc4215_update_device(dev);
113
Guenter Roeck790fa382012-01-19 11:02:21 -0800114 /*
115 * The strange looking conversions that follow are fixed-point
Ira Snyder72f5de92009-03-31 15:24:29 -0700116 * math, since we cannot do floating point in the kernel.
117 *
118 * Step 1: convert sense register to microVolts
119 * Step 2: convert voltage to milliAmperes
120 *
121 * If you play around with the V=IR equation, you come up with
122 * the following: X uV / Y mOhm == Z mA
123 *
124 * With the resistors that are fractions of a milliOhm, we multiply
125 * the voltage and resistance by 10, to shift the decimal point.
126 * Now we can use the normal division operator again.
127 */
128
129 /* Calculate voltage in microVolts (151 uV per increment) */
130 const unsigned int voltage = data->regs[LTC4215_SENSE] * 151;
131
132 /* Calculate current in milliAmperes (4 milliOhm sense resistor) */
133 const unsigned int curr = voltage / 4;
134
135 return curr;
136}
137
138static ssize_t ltc4215_show_voltage(struct device *dev,
139 struct device_attribute *da,
140 char *buf)
141{
142 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
143 const int voltage = ltc4215_get_voltage(dev, attr->index);
144
145 return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
146}
147
148static ssize_t ltc4215_show_current(struct device *dev,
149 struct device_attribute *da,
150 char *buf)
151{
152 const unsigned int curr = ltc4215_get_current(dev);
153
154 return snprintf(buf, PAGE_SIZE, "%u\n", curr);
155}
156
157static ssize_t ltc4215_show_power(struct device *dev,
158 struct device_attribute *da,
159 char *buf)
160{
161 const unsigned int curr = ltc4215_get_current(dev);
162 const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN);
163
164 /* current in mA * voltage in mV == power in uW */
165 const unsigned int power = abs(output_voltage * curr);
166
167 return snprintf(buf, PAGE_SIZE, "%u\n", power);
168}
169
170static ssize_t ltc4215_show_alarm(struct device *dev,
171 struct device_attribute *da,
172 char *buf)
173{
174 struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
175 struct ltc4215_data *data = ltc4215_update_device(dev);
176 const u8 reg = data->regs[attr->index];
177 const u32 mask = attr->nr;
178
179 return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
180}
181
Guenter Roeck790fa382012-01-19 11:02:21 -0800182/*
183 * These macros are used below in constructing device attribute objects
Ira Snyder72f5de92009-03-31 15:24:29 -0700184 * for use with sysfs_create_group() to make a sysfs device file
185 * for each register.
186 */
187
188#define LTC4215_VOLTAGE(name, ltc4215_cmd_idx) \
189 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
190 ltc4215_show_voltage, NULL, ltc4215_cmd_idx)
191
192#define LTC4215_CURRENT(name) \
193 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
194 ltc4215_show_current, NULL, 0);
195
196#define LTC4215_POWER(name) \
197 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
198 ltc4215_show_power, NULL, 0);
199
200#define LTC4215_ALARM(name, mask, reg) \
201 static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
202 ltc4215_show_alarm, NULL, (mask), reg)
203
204/* Construct a sensor_device_attribute structure for each register */
205
206/* Current */
207LTC4215_CURRENT(curr1_input);
208LTC4215_ALARM(curr1_max_alarm, (1 << 2), LTC4215_STATUS);
209
210/* Power (virtual) */
211LTC4215_POWER(power1_input);
Ira Snyder72f5de92009-03-31 15:24:29 -0700212
213/* Input Voltage */
214LTC4215_VOLTAGE(in1_input, LTC4215_ADIN);
215LTC4215_ALARM(in1_max_alarm, (1 << 0), LTC4215_STATUS);
216LTC4215_ALARM(in1_min_alarm, (1 << 1), LTC4215_STATUS);
217
218/* Output Voltage */
219LTC4215_VOLTAGE(in2_input, LTC4215_SOURCE);
Ira W. Snyder0a6bf652010-12-13 11:42:30 -0500220LTC4215_ALARM(in2_min_alarm, (1 << 3), LTC4215_STATUS);
Ira Snyder72f5de92009-03-31 15:24:29 -0700221
Guenter Roeck790fa382012-01-19 11:02:21 -0800222/*
223 * Finally, construct an array of pointers to members of the above objects,
Ira Snyder72f5de92009-03-31 15:24:29 -0700224 * as required for sysfs_create_group()
225 */
226static struct attribute *ltc4215_attributes[] = {
227 &sensor_dev_attr_curr1_input.dev_attr.attr,
228 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
229
230 &sensor_dev_attr_power1_input.dev_attr.attr,
Ira Snyder72f5de92009-03-31 15:24:29 -0700231
232 &sensor_dev_attr_in1_input.dev_attr.attr,
233 &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
234 &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
235
236 &sensor_dev_attr_in2_input.dev_attr.attr,
Ira W. Snyder0a6bf652010-12-13 11:42:30 -0500237 &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
Ira Snyder72f5de92009-03-31 15:24:29 -0700238
239 NULL,
240};
241
242static const struct attribute_group ltc4215_group = {
243 .attrs = ltc4215_attributes,
244};
245
246static int ltc4215_probe(struct i2c_client *client,
247 const struct i2c_device_id *id)
248{
Jean Delvare2d2a7cf2009-10-04 22:53:42 +0200249 struct i2c_adapter *adapter = client->adapter;
Ira Snyder72f5de92009-03-31 15:24:29 -0700250 struct ltc4215_data *data;
251 int ret;
252
Jean Delvare2d2a7cf2009-10-04 22:53:42 +0200253 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
254 return -ENODEV;
255
Ira Snyder72f5de92009-03-31 15:24:29 -0700256 data = kzalloc(sizeof(*data), GFP_KERNEL);
257 if (!data) {
258 ret = -ENOMEM;
259 goto out_kzalloc;
260 }
261
262 i2c_set_clientdata(client, data);
263 mutex_init(&data->update_lock);
264
265 /* Initialize the LTC4215 chip */
Ira W. Snyderb6b9d692009-09-23 22:59:43 +0200266 i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00);
Ira Snyder72f5de92009-03-31 15:24:29 -0700267
268 /* Register sysfs hooks */
269 ret = sysfs_create_group(&client->dev.kobj, &ltc4215_group);
270 if (ret)
271 goto out_sysfs_create_group;
272
273 data->hwmon_dev = hwmon_device_register(&client->dev);
274 if (IS_ERR(data->hwmon_dev)) {
275 ret = PTR_ERR(data->hwmon_dev);
276 goto out_hwmon_device_register;
277 }
278
279 return 0;
280
281out_hwmon_device_register:
282 sysfs_remove_group(&client->dev.kobj, &ltc4215_group);
283out_sysfs_create_group:
284 kfree(data);
285out_kzalloc:
286 return ret;
287}
288
289static int ltc4215_remove(struct i2c_client *client)
290{
291 struct ltc4215_data *data = i2c_get_clientdata(client);
292
293 hwmon_device_unregister(data->hwmon_dev);
294 sysfs_remove_group(&client->dev.kobj, &ltc4215_group);
295
296 kfree(data);
297
298 return 0;
299}
300
Ira Snyder72f5de92009-03-31 15:24:29 -0700301static const struct i2c_device_id ltc4215_id[] = {
Jean Delvare2d2a7cf2009-10-04 22:53:42 +0200302 { "ltc4215", 0 },
Ira Snyder72f5de92009-03-31 15:24:29 -0700303 { }
304};
305MODULE_DEVICE_TABLE(i2c, ltc4215_id);
306
307/* This is the driver that will be inserted */
308static struct i2c_driver ltc4215_driver = {
Ira Snyder72f5de92009-03-31 15:24:29 -0700309 .driver = {
310 .name = "ltc4215",
311 },
312 .probe = ltc4215_probe,
313 .remove = ltc4215_remove,
314 .id_table = ltc4215_id,
Ira Snyder72f5de92009-03-31 15:24:29 -0700315};
316
Axel Linf0967ee2012-01-20 15:38:18 +0800317module_i2c_driver(ltc4215_driver);
Ira Snyder72f5de92009-03-31 15:24:29 -0700318
319MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
320MODULE_DESCRIPTION("LTC4215 driver");
321MODULE_LICENSE("GPL");