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b886d83c | 1 | // SPDX-License-Identifier: GPL-2.0-only |
72f5de92 IS |
2 | /* |
3 | * Driver for Linear Technology LTC4215 I2C Hot Swap Controller | |
4 | * | |
5 | * Copyright (C) 2009 Ira W. Snyder <iws@ovro.caltech.edu> | |
6 | * | |
72f5de92 IS |
7 | * Datasheet: |
8 | * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697 | |
9 | */ | |
10 | ||
11 | #include <linux/kernel.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/err.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/i2c.h> | |
17 | #include <linux/hwmon.h> | |
18 | #include <linux/hwmon-sysfs.h> | |
dcd8f392 | 19 | #include <linux/jiffies.h> |
72f5de92 | 20 | |
72f5de92 IS |
21 | /* Here are names of the chip's registers (a.k.a. commands) */ |
22 | enum ltc4215_cmd { | |
23 | LTC4215_CONTROL = 0x00, /* rw */ | |
24 | LTC4215_ALERT = 0x01, /* rw */ | |
25 | LTC4215_STATUS = 0x02, /* ro */ | |
26 | LTC4215_FAULT = 0x03, /* rw */ | |
27 | LTC4215_SENSE = 0x04, /* rw */ | |
28 | LTC4215_SOURCE = 0x05, /* rw */ | |
29 | LTC4215_ADIN = 0x06, /* rw */ | |
30 | }; | |
31 | ||
32 | struct ltc4215_data { | |
6c588b45 | 33 | struct i2c_client *client; |
72f5de92 IS |
34 | |
35 | struct mutex update_lock; | |
36 | bool valid; | |
37 | unsigned long last_updated; /* in jiffies */ | |
38 | ||
39 | /* Registers */ | |
40 | u8 regs[7]; | |
41 | }; | |
42 | ||
43 | static struct ltc4215_data *ltc4215_update_device(struct device *dev) | |
44 | { | |
6c588b45 GR |
45 | struct ltc4215_data *data = dev_get_drvdata(dev); |
46 | struct i2c_client *client = data->client; | |
72f5de92 IS |
47 | s32 val; |
48 | int i; | |
49 | ||
50 | mutex_lock(&data->update_lock); | |
51 | ||
52 | /* The chip's A/D updates 10 times per second */ | |
53 | if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) { | |
54 | ||
55 | dev_dbg(&client->dev, "Starting ltc4215 update\n"); | |
56 | ||
57 | /* Read all registers */ | |
58 | for (i = 0; i < ARRAY_SIZE(data->regs); i++) { | |
59 | val = i2c_smbus_read_byte_data(client, i); | |
60 | if (unlikely(val < 0)) | |
61 | data->regs[i] = 0; | |
62 | else | |
63 | data->regs[i] = val; | |
64 | } | |
65 | ||
66 | data->last_updated = jiffies; | |
67 | data->valid = 1; | |
68 | } | |
69 | ||
70 | mutex_unlock(&data->update_lock); | |
71 | ||
72 | return data; | |
73 | } | |
74 | ||
75 | /* Return the voltage from the given register in millivolts */ | |
76 | static int ltc4215_get_voltage(struct device *dev, u8 reg) | |
77 | { | |
78 | struct ltc4215_data *data = ltc4215_update_device(dev); | |
79 | const u8 regval = data->regs[reg]; | |
80 | u32 voltage = 0; | |
81 | ||
82 | switch (reg) { | |
83 | case LTC4215_SENSE: | |
84 | /* 151 uV per increment */ | |
85 | voltage = regval * 151 / 1000; | |
86 | break; | |
87 | case LTC4215_SOURCE: | |
88 | /* 60.5 mV per increment */ | |
89 | voltage = regval * 605 / 10; | |
90 | break; | |
91 | case LTC4215_ADIN: | |
790fa38c GR |
92 | /* |
93 | * The ADIN input is divided by 12.5, and has 4.82 mV | |
94 | * per increment, so we have the additional multiply | |
95 | */ | |
72f5de92 IS |
96 | voltage = regval * 482 * 125 / 1000; |
97 | break; | |
98 | default: | |
99 | /* If we get here, the developer messed up */ | |
100 | WARN_ON_ONCE(1); | |
101 | break; | |
102 | } | |
103 | ||
104 | return voltage; | |
105 | } | |
106 | ||
107 | /* Return the current from the sense resistor in mA */ | |
108 | static unsigned int ltc4215_get_current(struct device *dev) | |
109 | { | |
110 | struct ltc4215_data *data = ltc4215_update_device(dev); | |
111 | ||
790fa38c GR |
112 | /* |
113 | * The strange looking conversions that follow are fixed-point | |
72f5de92 IS |
114 | * math, since we cannot do floating point in the kernel. |
115 | * | |
116 | * Step 1: convert sense register to microVolts | |
117 | * Step 2: convert voltage to milliAmperes | |
118 | * | |
119 | * If you play around with the V=IR equation, you come up with | |
120 | * the following: X uV / Y mOhm == Z mA | |
121 | * | |
122 | * With the resistors that are fractions of a milliOhm, we multiply | |
123 | * the voltage and resistance by 10, to shift the decimal point. | |
124 | * Now we can use the normal division operator again. | |
125 | */ | |
126 | ||
127 | /* Calculate voltage in microVolts (151 uV per increment) */ | |
128 | const unsigned int voltage = data->regs[LTC4215_SENSE] * 151; | |
129 | ||
130 | /* Calculate current in milliAmperes (4 milliOhm sense resistor) */ | |
131 | const unsigned int curr = voltage / 4; | |
132 | ||
133 | return curr; | |
134 | } | |
135 | ||
d7f2a8f5 GR |
136 | static ssize_t ltc4215_voltage_show(struct device *dev, |
137 | struct device_attribute *da, char *buf) | |
72f5de92 IS |
138 | { |
139 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); | |
140 | const int voltage = ltc4215_get_voltage(dev, attr->index); | |
141 | ||
142 | return snprintf(buf, PAGE_SIZE, "%d\n", voltage); | |
143 | } | |
144 | ||
d7f2a8f5 GR |
145 | static ssize_t ltc4215_current_show(struct device *dev, |
146 | struct device_attribute *da, char *buf) | |
72f5de92 IS |
147 | { |
148 | const unsigned int curr = ltc4215_get_current(dev); | |
149 | ||
150 | return snprintf(buf, PAGE_SIZE, "%u\n", curr); | |
151 | } | |
152 | ||
d7f2a8f5 GR |
153 | static ssize_t ltc4215_power_show(struct device *dev, |
154 | struct device_attribute *da, char *buf) | |
72f5de92 IS |
155 | { |
156 | const unsigned int curr = ltc4215_get_current(dev); | |
157 | const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN); | |
158 | ||
159 | /* current in mA * voltage in mV == power in uW */ | |
160 | const unsigned int power = abs(output_voltage * curr); | |
161 | ||
162 | return snprintf(buf, PAGE_SIZE, "%u\n", power); | |
163 | } | |
164 | ||
d7f2a8f5 GR |
165 | static ssize_t ltc4215_alarm_show(struct device *dev, |
166 | struct device_attribute *da, char *buf) | |
72f5de92 | 167 | { |
b5f0f1ea | 168 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
72f5de92 | 169 | struct ltc4215_data *data = ltc4215_update_device(dev); |
b5f0f1ea GR |
170 | const u8 reg = data->regs[LTC4215_STATUS]; |
171 | const u32 mask = attr->index; | |
72f5de92 | 172 | |
b5f0f1ea | 173 | return snprintf(buf, PAGE_SIZE, "%u\n", !!(reg & mask)); |
72f5de92 IS |
174 | } |
175 | ||
790fa38c GR |
176 | /* |
177 | * These macros are used below in constructing device attribute objects | |
72f5de92 IS |
178 | * for use with sysfs_create_group() to make a sysfs device file |
179 | * for each register. | |
180 | */ | |
181 | ||
72f5de92 IS |
182 | /* Construct a sensor_device_attribute structure for each register */ |
183 | ||
184 | /* Current */ | |
d7f2a8f5 GR |
185 | static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4215_current, 0); |
186 | static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4215_alarm, 1 << 2); | |
72f5de92 IS |
187 | |
188 | /* Power (virtual) */ | |
d7f2a8f5 | 189 | static SENSOR_DEVICE_ATTR_RO(power1_input, ltc4215_power, 0); |
72f5de92 IS |
190 | |
191 | /* Input Voltage */ | |
d7f2a8f5 GR |
192 | static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4215_voltage, LTC4215_ADIN); |
193 | static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4215_alarm, 1 << 0); | |
194 | static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4215_alarm, 1 << 1); | |
72f5de92 IS |
195 | |
196 | /* Output Voltage */ | |
d7f2a8f5 GR |
197 | static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4215_voltage, LTC4215_SOURCE); |
198 | static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4215_alarm, 1 << 3); | |
72f5de92 | 199 | |
790fa38c GR |
200 | /* |
201 | * Finally, construct an array of pointers to members of the above objects, | |
72f5de92 IS |
202 | * as required for sysfs_create_group() |
203 | */ | |
6c588b45 | 204 | static struct attribute *ltc4215_attrs[] = { |
72f5de92 IS |
205 | &sensor_dev_attr_curr1_input.dev_attr.attr, |
206 | &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, | |
207 | ||
208 | &sensor_dev_attr_power1_input.dev_attr.attr, | |
72f5de92 IS |
209 | |
210 | &sensor_dev_attr_in1_input.dev_attr.attr, | |
211 | &sensor_dev_attr_in1_max_alarm.dev_attr.attr, | |
212 | &sensor_dev_attr_in1_min_alarm.dev_attr.attr, | |
213 | ||
214 | &sensor_dev_attr_in2_input.dev_attr.attr, | |
0a6bf658 | 215 | &sensor_dev_attr_in2_min_alarm.dev_attr.attr, |
72f5de92 IS |
216 | |
217 | NULL, | |
218 | }; | |
6c588b45 | 219 | ATTRIBUTE_GROUPS(ltc4215); |
72f5de92 IS |
220 | |
221 | static int ltc4215_probe(struct i2c_client *client, | |
222 | const struct i2c_device_id *id) | |
223 | { | |
2d2a7cff | 224 | struct i2c_adapter *adapter = client->adapter; |
6c588b45 | 225 | struct device *dev = &client->dev; |
72f5de92 | 226 | struct ltc4215_data *data; |
6c588b45 | 227 | struct device *hwmon_dev; |
72f5de92 | 228 | |
2d2a7cff JD |
229 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) |
230 | return -ENODEV; | |
231 | ||
6c588b45 | 232 | data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); |
d2b95e58 GR |
233 | if (!data) |
234 | return -ENOMEM; | |
72f5de92 | 235 | |
6c588b45 | 236 | data->client = client; |
72f5de92 IS |
237 | mutex_init(&data->update_lock); |
238 | ||
239 | /* Initialize the LTC4215 chip */ | |
b6b9d696 | 240 | i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00); |
72f5de92 | 241 | |
6c588b45 GR |
242 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, |
243 | data, | |
244 | ltc4215_groups); | |
245 | return PTR_ERR_OR_ZERO(hwmon_dev); | |
72f5de92 IS |
246 | } |
247 | ||
72f5de92 | 248 | static const struct i2c_device_id ltc4215_id[] = { |
2d2a7cff | 249 | { "ltc4215", 0 }, |
72f5de92 IS |
250 | { } |
251 | }; | |
252 | MODULE_DEVICE_TABLE(i2c, ltc4215_id); | |
253 | ||
254 | /* This is the driver that will be inserted */ | |
255 | static struct i2c_driver ltc4215_driver = { | |
72f5de92 IS |
256 | .driver = { |
257 | .name = "ltc4215", | |
258 | }, | |
259 | .probe = ltc4215_probe, | |
72f5de92 | 260 | .id_table = ltc4215_id, |
72f5de92 IS |
261 | }; |
262 | ||
f0967eea | 263 | module_i2c_driver(ltc4215_driver); |
72f5de92 IS |
264 | |
265 | MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); | |
266 | MODULE_DESCRIPTION("LTC4215 driver"); | |
267 | MODULE_LICENSE("GPL"); |