1 /* 2 * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver 3 * 4 * Written by: Grant Likely <grant.likely@secretlab.ca> 5 * 6 * Copyright (C) 2007 Secret Lab Technologies Ltd. 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 /* 14 * The DS1682 elapsed timer recorder is a simple device that implements 15 * one elapsed time counter, one event counter, an alarm signal and 10 16 * bytes of general purpose EEPROM. 17 * 18 * This driver provides access to the DS1682 counters and user data via 19 * the sysfs. The following attributes are added to the device node: 20 * elapsed_time (u32): Total elapsed event time in ms resolution 21 * alarm_time (u32): When elapsed time exceeds the value in alarm_time, 22 * then the alarm pin is asserted. 23 * event_count (u16): number of times the event pin has gone low. 24 * eeprom (u8[10]): general purpose EEPROM 25 * 26 * Counter registers and user data are both read/write unless the device 27 * has been write protected. This driver does not support turning off write 28 * protection. Once write protection is turned on, it is impossible to 29 * turn it off again, so I have left the feature out of this driver to avoid 30 * accidental enabling, but it is trivial to add write protect support. 31 * 32 */ 33 34 #include <linux/module.h> 35 #include <linux/init.h> 36 #include <linux/i2c.h> 37 #include <linux/string.h> 38 #include <linux/list.h> 39 #include <linux/sysfs.h> 40 #include <linux/ctype.h> 41 #include <linux/hwmon-sysfs.h> 42 43 /* Device registers */ 44 #define DS1682_REG_CONFIG 0x00 45 #define DS1682_REG_ALARM 0x01 46 #define DS1682_REG_ELAPSED 0x05 47 #define DS1682_REG_EVT_CNTR 0x09 48 #define DS1682_REG_EEPROM 0x0b 49 #define DS1682_REG_RESET 0x1d 50 #define DS1682_REG_WRITE_DISABLE 0x1e 51 #define DS1682_REG_WRITE_MEM_DISABLE 0x1f 52 53 #define DS1682_EEPROM_SIZE 10 54 55 /* 56 * Generic counter attributes 57 */ 58 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr, 59 char *buf) 60 { 61 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 62 struct i2c_client *client = to_i2c_client(dev); 63 __le32 val = 0; 64 int rc; 65 66 dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name); 67 68 /* Read the register */ 69 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr, 70 (u8 *) & val); 71 if (rc < 0) 72 return -EIO; 73 74 /* Special case: the 32 bit regs are time values with 1/4s 75 * resolution, scale them up to milliseconds */ 76 if (sattr->nr == 4) 77 return sprintf(buf, "%llu\n", 78 ((unsigned long long)le32_to_cpu(val)) * 250); 79 80 /* Format the output string and return # of bytes */ 81 return sprintf(buf, "%li\n", (long)le32_to_cpu(val)); 82 } 83 84 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr, 85 const char *buf, size_t count) 86 { 87 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 88 struct i2c_client *client = to_i2c_client(dev); 89 char *endp; 90 u64 val; 91 __le32 val_le; 92 int rc; 93 94 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name); 95 96 /* Decode input */ 97 val = simple_strtoull(buf, &endp, 0); 98 if (buf == endp) { 99 dev_dbg(dev, "input string not a number\n"); 100 return -EINVAL; 101 } 102 103 /* Special case: the 32 bit regs are time values with 1/4s 104 * resolution, scale input down to quarter-seconds */ 105 if (sattr->nr == 4) 106 do_div(val, 250); 107 108 /* write out the value */ 109 val_le = cpu_to_le32(val); 110 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr, 111 (u8 *) & val_le); 112 if (rc < 0) { 113 dev_err(dev, "register write failed; reg=0x%x, size=%i\n", 114 sattr->index, sattr->nr); 115 return -EIO; 116 } 117 118 return count; 119 } 120 121 /* 122 * Simple register attributes 123 */ 124 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show, 125 ds1682_store, 4, DS1682_REG_ELAPSED); 126 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show, 127 ds1682_store, 4, DS1682_REG_ALARM); 128 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show, 129 ds1682_store, 2, DS1682_REG_EVT_CNTR); 130 131 static const struct attribute_group ds1682_group = { 132 .attrs = (struct attribute *[]) { 133 &sensor_dev_attr_elapsed_time.dev_attr.attr, 134 &sensor_dev_attr_alarm_time.dev_attr.attr, 135 &sensor_dev_attr_event_count.dev_attr.attr, 136 NULL, 137 }, 138 }; 139 140 /* 141 * User data attribute 142 */ 143 static ssize_t ds1682_eeprom_read(struct kobject *kobj, struct bin_attribute *attr, 144 char *buf, loff_t off, size_t count) 145 { 146 struct i2c_client *client = kobj_to_i2c_client(kobj); 147 int rc; 148 149 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n", 150 buf, off, count); 151 152 if (off >= DS1682_EEPROM_SIZE) 153 return 0; 154 155 if (off + count > DS1682_EEPROM_SIZE) 156 count = DS1682_EEPROM_SIZE - off; 157 158 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off, 159 count, buf); 160 if (rc < 0) 161 return -EIO; 162 163 return count; 164 } 165 166 static ssize_t ds1682_eeprom_write(struct kobject *kobj, struct bin_attribute *attr, 167 char *buf, loff_t off, size_t count) 168 { 169 struct i2c_client *client = kobj_to_i2c_client(kobj); 170 171 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n", 172 buf, off, count); 173 174 if (off >= DS1682_EEPROM_SIZE) 175 return -ENOSPC; 176 177 if (off + count > DS1682_EEPROM_SIZE) 178 count = DS1682_EEPROM_SIZE - off; 179 180 /* Write out to the device */ 181 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off, 182 count, buf) < 0) 183 return -EIO; 184 185 return count; 186 } 187 188 static struct bin_attribute ds1682_eeprom_attr = { 189 .attr = { 190 .name = "eeprom", 191 .mode = S_IRUGO | S_IWUSR, 192 }, 193 .size = DS1682_EEPROM_SIZE, 194 .read = ds1682_eeprom_read, 195 .write = ds1682_eeprom_write, 196 }; 197 198 /* 199 * Called when a ds1682 device is matched with this driver 200 */ 201 static int ds1682_probe(struct i2c_client *client, 202 const struct i2c_device_id *id) 203 { 204 int rc; 205 206 if (!i2c_check_functionality(client->adapter, 207 I2C_FUNC_SMBUS_I2C_BLOCK)) { 208 dev_err(&client->dev, "i2c bus does not support the ds1682\n"); 209 rc = -ENODEV; 210 goto exit; 211 } 212 213 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group); 214 if (rc) 215 goto exit; 216 217 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 218 if (rc) 219 goto exit_bin_attr; 220 221 return 0; 222 223 exit_bin_attr: 224 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 225 exit: 226 return rc; 227 } 228 229 static int ds1682_remove(struct i2c_client *client) 230 { 231 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 232 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 233 return 0; 234 } 235 236 static const struct i2c_device_id ds1682_id[] = { 237 { "ds1682", 0 }, 238 { } 239 }; 240 MODULE_DEVICE_TABLE(i2c, ds1682_id); 241 242 static struct i2c_driver ds1682_driver = { 243 .driver = { 244 .name = "ds1682", 245 }, 246 .probe = ds1682_probe, 247 .remove = ds1682_remove, 248 .id_table = ds1682_id, 249 }; 250 251 static int __init ds1682_init(void) 252 { 253 return i2c_add_driver(&ds1682_driver); 254 } 255 256 static void __exit ds1682_exit(void) 257 { 258 i2c_del_driver(&ds1682_driver); 259 } 260 261 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); 262 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver"); 263 MODULE_LICENSE("GPL"); 264 265 module_init(ds1682_init); 266 module_exit(ds1682_exit); 267