Guenter Roeck | e5f5c99 | 2010-06-25 11:59:54 -0700 | [diff] [blame] | 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 | |
| 37 | /* chip registers */ |
| 38 | #define LTC4261_STATUS 0x00 /* readonly */ |
| 39 | #define LTC4261_FAULT 0x01 |
| 40 | #define LTC4261_ALERT 0x02 |
| 41 | #define LTC4261_CONTROL 0x03 |
| 42 | #define LTC4261_SENSE_H 0x04 |
| 43 | #define LTC4261_SENSE_L 0x05 |
| 44 | #define LTC4261_ADIN2_H 0x06 |
| 45 | #define LTC4261_ADIN2_L 0x07 |
| 46 | #define LTC4261_ADIN_H 0x08 |
| 47 | #define LTC4261_ADIN_L 0x09 |
| 48 | |
| 49 | /* |
| 50 | * Fault register bits |
| 51 | */ |
| 52 | #define FAULT_OV (1<<0) |
| 53 | #define FAULT_UV (1<<1) |
| 54 | #define FAULT_OC (1<<2) |
| 55 | |
| 56 | struct ltc4261_data { |
| 57 | struct device *hwmon_dev; |
| 58 | |
| 59 | struct mutex update_lock; |
| 60 | bool valid; |
| 61 | unsigned long last_updated; /* in jiffies */ |
| 62 | |
| 63 | /* Registers */ |
| 64 | u8 regs[10]; |
| 65 | }; |
| 66 | |
| 67 | static struct ltc4261_data *ltc4261_update_device(struct device *dev) |
| 68 | { |
| 69 | struct i2c_client *client = to_i2c_client(dev); |
| 70 | struct ltc4261_data *data = i2c_get_clientdata(client); |
| 71 | struct ltc4261_data *ret = data; |
| 72 | |
| 73 | mutex_lock(&data->update_lock); |
| 74 | |
| 75 | if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) { |
| 76 | int i; |
| 77 | |
| 78 | /* Read registers -- 0x00 to 0x09 */ |
| 79 | for (i = 0; i < ARRAY_SIZE(data->regs); i++) { |
| 80 | int val; |
| 81 | |
| 82 | val = i2c_smbus_read_byte_data(client, i); |
| 83 | if (unlikely(val < 0)) { |
| 84 | dev_dbg(dev, |
Guenter Roeck | 69f8b74 | 2010-10-26 15:59:21 -0700 | [diff] [blame] | 85 | "Failed to read ADC value: error %d\n", |
Guenter Roeck | e5f5c99 | 2010-06-25 11:59:54 -0700 | [diff] [blame] | 86 | val); |
| 87 | ret = ERR_PTR(val); |
Frans Meulenbroeks | aac9fe9 | 2012-01-02 12:03:20 +0100 | [diff] [blame] | 88 | data->valid = 0; |
Guenter Roeck | e5f5c99 | 2010-06-25 11:59:54 -0700 | [diff] [blame] | 89 | goto abort; |
| 90 | } |
| 91 | data->regs[i] = val; |
| 92 | } |
| 93 | data->last_updated = jiffies; |
| 94 | data->valid = 1; |
| 95 | } |
| 96 | abort: |
| 97 | mutex_unlock(&data->update_lock); |
| 98 | return ret; |
| 99 | } |
| 100 | |
| 101 | /* Return the voltage from the given register in mV or mA */ |
| 102 | static int ltc4261_get_value(struct ltc4261_data *data, u8 reg) |
| 103 | { |
| 104 | u32 val; |
| 105 | |
| 106 | val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6); |
| 107 | |
| 108 | switch (reg) { |
| 109 | case LTC4261_ADIN_H: |
| 110 | case LTC4261_ADIN2_H: |
| 111 | /* 2.5mV resolution. Convert to mV. */ |
| 112 | val = val * 25 / 10; |
| 113 | break; |
| 114 | case LTC4261_SENSE_H: |
| 115 | /* |
| 116 | * 62.5uV resolution. Convert to current as measured with |
| 117 | * an 1 mOhm sense resistor, in mA. If a different sense |
| 118 | * resistor is installed, calculate the actual current by |
| 119 | * dividing the reported current by the sense resistor value |
| 120 | * in mOhm. |
| 121 | */ |
| 122 | val = val * 625 / 10; |
| 123 | break; |
| 124 | default: |
| 125 | /* If we get here, the developer messed up */ |
| 126 | WARN_ON_ONCE(1); |
| 127 | val = 0; |
| 128 | break; |
| 129 | } |
| 130 | |
| 131 | return val; |
| 132 | } |
| 133 | |
| 134 | static ssize_t ltc4261_show_value(struct device *dev, |
| 135 | struct device_attribute *da, char *buf) |
| 136 | { |
| 137 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
| 138 | struct ltc4261_data *data = ltc4261_update_device(dev); |
| 139 | int value; |
| 140 | |
| 141 | if (IS_ERR(data)) |
| 142 | return PTR_ERR(data); |
| 143 | |
| 144 | value = ltc4261_get_value(data, attr->index); |
| 145 | return snprintf(buf, PAGE_SIZE, "%d\n", value); |
| 146 | } |
| 147 | |
| 148 | static ssize_t ltc4261_show_bool(struct device *dev, |
| 149 | struct device_attribute *da, char *buf) |
| 150 | { |
| 151 | struct sensor_device_attribute *attr = to_sensor_dev_attr(da); |
| 152 | struct i2c_client *client = to_i2c_client(dev); |
| 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(client, LTC4261_FAULT, ~fault); |
| 162 | |
| 163 | return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0); |
| 164 | } |
| 165 | |
| 166 | /* |
| 167 | * These macros are used below in constructing device attribute objects |
| 168 | * for use with sysfs_create_group() to make a sysfs device file |
| 169 | * for each register. |
| 170 | */ |
| 171 | |
| 172 | #define LTC4261_VALUE(name, ltc4261_cmd_idx) \ |
| 173 | static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ |
| 174 | ltc4261_show_value, NULL, ltc4261_cmd_idx) |
| 175 | |
| 176 | #define LTC4261_BOOL(name, mask) \ |
| 177 | static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ |
| 178 | ltc4261_show_bool, NULL, (mask)) |
| 179 | |
| 180 | /* |
| 181 | * Input voltages. |
| 182 | */ |
| 183 | LTC4261_VALUE(in1_input, LTC4261_ADIN_H); |
| 184 | LTC4261_VALUE(in2_input, LTC4261_ADIN2_H); |
| 185 | |
| 186 | /* |
| 187 | * Voltage alarms. The chip has only one set of voltage alarm status bits, |
| 188 | * triggered by input voltage alarms. In many designs, those alarms are |
| 189 | * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin |
| 190 | * to the OV pin. ADIN2 is, however, not available on all chip variants. |
| 191 | * To ensure that the alarm condition is reported to the user, report it |
| 192 | * with both voltage sensors. |
| 193 | */ |
| 194 | LTC4261_BOOL(in1_min_alarm, FAULT_UV); |
| 195 | LTC4261_BOOL(in1_max_alarm, FAULT_OV); |
| 196 | LTC4261_BOOL(in2_min_alarm, FAULT_UV); |
| 197 | LTC4261_BOOL(in2_max_alarm, FAULT_OV); |
| 198 | |
| 199 | /* Currents (via sense resistor) */ |
| 200 | LTC4261_VALUE(curr1_input, LTC4261_SENSE_H); |
| 201 | |
| 202 | /* Overcurrent alarm */ |
| 203 | LTC4261_BOOL(curr1_max_alarm, FAULT_OC); |
| 204 | |
| 205 | static struct attribute *ltc4261_attributes[] = { |
| 206 | &sensor_dev_attr_in1_input.dev_attr.attr, |
| 207 | &sensor_dev_attr_in1_min_alarm.dev_attr.attr, |
| 208 | &sensor_dev_attr_in1_max_alarm.dev_attr.attr, |
| 209 | &sensor_dev_attr_in2_input.dev_attr.attr, |
| 210 | &sensor_dev_attr_in2_min_alarm.dev_attr.attr, |
| 211 | &sensor_dev_attr_in2_max_alarm.dev_attr.attr, |
| 212 | |
| 213 | &sensor_dev_attr_curr1_input.dev_attr.attr, |
| 214 | &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, |
| 215 | |
| 216 | NULL, |
| 217 | }; |
| 218 | |
| 219 | static const struct attribute_group ltc4261_group = { |
| 220 | .attrs = ltc4261_attributes, |
| 221 | }; |
| 222 | |
| 223 | static int ltc4261_probe(struct i2c_client *client, |
| 224 | const struct i2c_device_id *id) |
| 225 | { |
| 226 | struct i2c_adapter *adapter = client->adapter; |
| 227 | struct ltc4261_data *data; |
| 228 | int ret; |
| 229 | |
| 230 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) |
| 231 | return -ENODEV; |
| 232 | |
| 233 | if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) { |
Jean Delvare | 475200c | 2010-11-05 10:59:29 -0400 | [diff] [blame] | 234 | dev_err(&client->dev, "Failed to read status register\n"); |
Guenter Roeck | e5f5c99 | 2010-06-25 11:59:54 -0700 | [diff] [blame] | 235 | return -ENODEV; |
| 236 | } |
| 237 | |
| 238 | data = kzalloc(sizeof(*data), GFP_KERNEL); |
| 239 | if (!data) { |
| 240 | ret = -ENOMEM; |
| 241 | goto out_kzalloc; |
| 242 | } |
| 243 | |
| 244 | i2c_set_clientdata(client, data); |
| 245 | mutex_init(&data->update_lock); |
| 246 | |
| 247 | /* Clear faults */ |
| 248 | i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00); |
| 249 | |
| 250 | /* Register sysfs hooks */ |
| 251 | ret = sysfs_create_group(&client->dev.kobj, <c4261_group); |
| 252 | if (ret) |
| 253 | goto out_sysfs_create_group; |
| 254 | |
| 255 | data->hwmon_dev = hwmon_device_register(&client->dev); |
| 256 | if (IS_ERR(data->hwmon_dev)) { |
| 257 | ret = PTR_ERR(data->hwmon_dev); |
| 258 | goto out_hwmon_device_register; |
| 259 | } |
| 260 | |
| 261 | return 0; |
| 262 | |
| 263 | out_hwmon_device_register: |
| 264 | sysfs_remove_group(&client->dev.kobj, <c4261_group); |
| 265 | out_sysfs_create_group: |
| 266 | kfree(data); |
| 267 | out_kzalloc: |
| 268 | return ret; |
| 269 | } |
| 270 | |
| 271 | static int ltc4261_remove(struct i2c_client *client) |
| 272 | { |
| 273 | struct ltc4261_data *data = i2c_get_clientdata(client); |
| 274 | |
| 275 | hwmon_device_unregister(data->hwmon_dev); |
| 276 | sysfs_remove_group(&client->dev.kobj, <c4261_group); |
| 277 | |
| 278 | kfree(data); |
| 279 | |
| 280 | return 0; |
| 281 | } |
| 282 | |
| 283 | static const struct i2c_device_id ltc4261_id[] = { |
| 284 | {"ltc4261", 0}, |
| 285 | {} |
| 286 | }; |
| 287 | |
| 288 | MODULE_DEVICE_TABLE(i2c, ltc4261_id); |
| 289 | |
| 290 | /* This is the driver that will be inserted */ |
| 291 | static struct i2c_driver ltc4261_driver = { |
| 292 | .driver = { |
| 293 | .name = "ltc4261", |
| 294 | }, |
| 295 | .probe = ltc4261_probe, |
| 296 | .remove = ltc4261_remove, |
| 297 | .id_table = ltc4261_id, |
| 298 | }; |
| 299 | |
Axel Lin | f0967ee | 2012-01-20 15:38:18 +0800 | [diff] [blame] | 300 | module_i2c_driver(ltc4261_driver); |
Guenter Roeck | e5f5c99 | 2010-06-25 11:59:54 -0700 | [diff] [blame] | 301 | |
| 302 | MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>"); |
| 303 | MODULE_DESCRIPTION("LTC4261 driver"); |
| 304 | MODULE_LICENSE("GPL"); |