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/i2c.h> 36 #include <linux/string.h> 37 #include <linux/list.h> 38 #include <linux/sysfs.h> 39 #include <linux/ctype.h> 40 #include <linux/hwmon-sysfs.h> 41 42 /* Device registers */ 43 #define DS1682_REG_CONFIG 0x00 44 #define DS1682_REG_ALARM 0x01 45 #define DS1682_REG_ELAPSED 0x05 46 #define DS1682_REG_EVT_CNTR 0x09 47 #define DS1682_REG_EEPROM 0x0b 48 #define DS1682_REG_RESET 0x1d 49 #define DS1682_REG_WRITE_DISABLE 0x1e 50 #define DS1682_REG_WRITE_MEM_DISABLE 0x1f 51 52 #define DS1682_EEPROM_SIZE 10 53 54 /* 55 * Generic counter attributes 56 */ 57 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr, 58 char *buf) 59 { 60 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 61 struct i2c_client *client = to_i2c_client(dev); 62 __le32 val = 0; 63 int rc; 64 65 dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name); 66 67 /* Read the register */ 68 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr, 69 (u8 *) & val); 70 if (rc < 0) 71 return -EIO; 72 73 /* Special case: the 32 bit regs are time values with 1/4s 74 * resolution, scale them up to milliseconds */ 75 if (sattr->nr == 4) 76 return sprintf(buf, "%llu\n", 77 ((unsigned long long)le32_to_cpu(val)) * 250); 78 79 /* Format the output string and return # of bytes */ 80 return sprintf(buf, "%li\n", (long)le32_to_cpu(val)); 81 } 82 83 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr, 84 const char *buf, size_t count) 85 { 86 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 87 struct i2c_client *client = to_i2c_client(dev); 88 u64 val; 89 __le32 val_le; 90 int rc; 91 92 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name); 93 94 /* Decode input */ 95 rc = kstrtoull(buf, 0, &val); 96 if (rc < 0) { 97 dev_dbg(dev, "input string not a number\n"); 98 return -EINVAL; 99 } 100 101 /* Special case: the 32 bit regs are time values with 1/4s 102 * resolution, scale input down to quarter-seconds */ 103 if (sattr->nr == 4) 104 do_div(val, 250); 105 106 /* write out the value */ 107 val_le = cpu_to_le32(val); 108 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr, 109 (u8 *) & val_le); 110 if (rc < 0) { 111 dev_err(dev, "register write failed; reg=0x%x, size=%i\n", 112 sattr->index, sattr->nr); 113 return -EIO; 114 } 115 116 return count; 117 } 118 119 /* 120 * Simple register attributes 121 */ 122 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show, 123 ds1682_store, 4, DS1682_REG_ELAPSED); 124 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show, 125 ds1682_store, 4, DS1682_REG_ALARM); 126 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show, 127 ds1682_store, 2, DS1682_REG_EVT_CNTR); 128 129 static const struct attribute_group ds1682_group = { 130 .attrs = (struct attribute *[]) { 131 &sensor_dev_attr_elapsed_time.dev_attr.attr, 132 &sensor_dev_attr_alarm_time.dev_attr.attr, 133 &sensor_dev_attr_event_count.dev_attr.attr, 134 NULL, 135 }, 136 }; 137 138 /* 139 * User data attribute 140 */ 141 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj, 142 struct bin_attribute *attr, 143 char *buf, loff_t off, size_t count) 144 { 145 struct i2c_client *client = kobj_to_i2c_client(kobj); 146 int rc; 147 148 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n", 149 buf, off, count); 150 151 if (off >= DS1682_EEPROM_SIZE) 152 return 0; 153 154 if (off + count > DS1682_EEPROM_SIZE) 155 count = DS1682_EEPROM_SIZE - off; 156 157 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off, 158 count, buf); 159 if (rc < 0) 160 return -EIO; 161 162 return count; 163 } 164 165 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj, 166 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 module_i2c_driver(ds1682_driver); 252 253 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); 254 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver"); 255 MODULE_LICENSE("GPL"); 256