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 unsigned long long val, check; 63 __le32 val_le = 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_le); 71 if (rc < 0) 72 return -EIO; 73 74 val = le32_to_cpu(val_le); 75 76 if (sattr->index == DS1682_REG_ELAPSED) { 77 int retries = 5; 78 79 /* Detect and retry when a tick occurs mid-read */ 80 do { 81 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, 82 sattr->nr, 83 (u8 *)&val_le); 84 if (rc < 0 || retries <= 0) 85 return -EIO; 86 87 check = val; 88 val = le32_to_cpu(val_le); 89 retries--; 90 } while (val != check && val != (check + 1)); 91 } 92 93 /* Format the output string and return # of bytes 94 * Special case: the 32 bit regs are time values with 1/4s 95 * resolution, scale them up to milliseconds 96 */ 97 return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val); 98 } 99 100 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr, 101 const char *buf, size_t count) 102 { 103 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 104 struct i2c_client *client = to_i2c_client(dev); 105 u64 val; 106 __le32 val_le; 107 int rc; 108 109 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name); 110 111 /* Decode input */ 112 rc = kstrtoull(buf, 0, &val); 113 if (rc < 0) { 114 dev_dbg(dev, "input string not a number\n"); 115 return -EINVAL; 116 } 117 118 /* Special case: the 32 bit regs are time values with 1/4s 119 * resolution, scale input down to quarter-seconds */ 120 if (sattr->nr == 4) 121 do_div(val, 250); 122 123 /* write out the value */ 124 val_le = cpu_to_le32(val); 125 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr, 126 (u8 *) & val_le); 127 if (rc < 0) { 128 dev_err(dev, "register write failed; reg=0x%x, size=%i\n", 129 sattr->index, sattr->nr); 130 return -EIO; 131 } 132 133 return count; 134 } 135 136 /* 137 * Simple register attributes 138 */ 139 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show, 140 ds1682_store, 4, DS1682_REG_ELAPSED); 141 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show, 142 ds1682_store, 4, DS1682_REG_ALARM); 143 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show, 144 ds1682_store, 2, DS1682_REG_EVT_CNTR); 145 146 static const struct attribute_group ds1682_group = { 147 .attrs = (struct attribute *[]) { 148 &sensor_dev_attr_elapsed_time.dev_attr.attr, 149 &sensor_dev_attr_alarm_time.dev_attr.attr, 150 &sensor_dev_attr_event_count.dev_attr.attr, 151 NULL, 152 }, 153 }; 154 155 /* 156 * User data attribute 157 */ 158 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj, 159 struct bin_attribute *attr, 160 char *buf, loff_t off, size_t count) 161 { 162 struct i2c_client *client = kobj_to_i2c_client(kobj); 163 int rc; 164 165 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n", 166 buf, off, count); 167 168 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off, 169 count, buf); 170 if (rc < 0) 171 return -EIO; 172 173 return count; 174 } 175 176 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj, 177 struct bin_attribute *attr, 178 char *buf, loff_t off, size_t count) 179 { 180 struct i2c_client *client = kobj_to_i2c_client(kobj); 181 182 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n", 183 buf, off, count); 184 185 /* Write out to the device */ 186 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off, 187 count, buf) < 0) 188 return -EIO; 189 190 return count; 191 } 192 193 static const struct bin_attribute ds1682_eeprom_attr = { 194 .attr = { 195 .name = "eeprom", 196 .mode = S_IRUGO | S_IWUSR, 197 }, 198 .size = DS1682_EEPROM_SIZE, 199 .read = ds1682_eeprom_read, 200 .write = ds1682_eeprom_write, 201 }; 202 203 /* 204 * Called when a ds1682 device is matched with this driver 205 */ 206 static int ds1682_probe(struct i2c_client *client, 207 const struct i2c_device_id *id) 208 { 209 int rc; 210 211 if (!i2c_check_functionality(client->adapter, 212 I2C_FUNC_SMBUS_I2C_BLOCK)) { 213 dev_err(&client->dev, "i2c bus does not support the ds1682\n"); 214 rc = -ENODEV; 215 goto exit; 216 } 217 218 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group); 219 if (rc) 220 goto exit; 221 222 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 223 if (rc) 224 goto exit_bin_attr; 225 226 return 0; 227 228 exit_bin_attr: 229 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 230 exit: 231 return rc; 232 } 233 234 static int ds1682_remove(struct i2c_client *client) 235 { 236 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 237 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 238 return 0; 239 } 240 241 static const struct i2c_device_id ds1682_id[] = { 242 { "ds1682", 0 }, 243 { } 244 }; 245 MODULE_DEVICE_TABLE(i2c, ds1682_id); 246 247 static const struct of_device_id ds1682_of_match[] = { 248 { .compatible = "dallas,ds1682", }, 249 {} 250 }; 251 MODULE_DEVICE_TABLE(of, ds1682_of_match); 252 253 static struct i2c_driver ds1682_driver = { 254 .driver = { 255 .name = "ds1682", 256 .of_match_table = ds1682_of_match, 257 }, 258 .probe = ds1682_probe, 259 .remove = ds1682_remove, 260 .id_table = ds1682_id, 261 }; 262 263 module_i2c_driver(ds1682_driver); 264 265 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); 266 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver"); 267 MODULE_LICENSE("GPL"); 268