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 char *endp; 89 u64 val; 90 __le32 val_le; 91 int rc; 92 93 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name); 94 95 /* Decode input */ 96 val = simple_strtoull(buf, &endp, 0); 97 if (buf == endp) { 98 dev_dbg(dev, "input string not a number\n"); 99 return -EINVAL; 100 } 101 102 /* Special case: the 32 bit regs are time values with 1/4s 103 * resolution, scale input down to quarter-seconds */ 104 if (sattr->nr == 4) 105 do_div(val, 250); 106 107 /* write out the value */ 108 val_le = cpu_to_le32(val); 109 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr, 110 (u8 *) & val_le); 111 if (rc < 0) { 112 dev_err(dev, "register write failed; reg=0x%x, size=%i\n", 113 sattr->index, sattr->nr); 114 return -EIO; 115 } 116 117 return count; 118 } 119 120 /* 121 * Simple register attributes 122 */ 123 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show, 124 ds1682_store, 4, DS1682_REG_ELAPSED); 125 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show, 126 ds1682_store, 4, DS1682_REG_ALARM); 127 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show, 128 ds1682_store, 2, DS1682_REG_EVT_CNTR); 129 130 static const struct attribute_group ds1682_group = { 131 .attrs = (struct attribute *[]) { 132 &sensor_dev_attr_elapsed_time.dev_attr.attr, 133 &sensor_dev_attr_alarm_time.dev_attr.attr, 134 &sensor_dev_attr_event_count.dev_attr.attr, 135 NULL, 136 }, 137 }; 138 139 /* 140 * User data attribute 141 */ 142 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj, 143 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 file *filp, struct kobject *kobj, 167 struct bin_attribute *attr, 168 char *buf, loff_t off, size_t count) 169 { 170 struct i2c_client *client = kobj_to_i2c_client(kobj); 171 172 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n", 173 buf, off, count); 174 175 if (off >= DS1682_EEPROM_SIZE) 176 return -ENOSPC; 177 178 if (off + count > DS1682_EEPROM_SIZE) 179 count = DS1682_EEPROM_SIZE - off; 180 181 /* Write out to the device */ 182 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off, 183 count, buf) < 0) 184 return -EIO; 185 186 return count; 187 } 188 189 static struct bin_attribute ds1682_eeprom_attr = { 190 .attr = { 191 .name = "eeprom", 192 .mode = S_IRUGO | S_IWUSR, 193 }, 194 .size = DS1682_EEPROM_SIZE, 195 .read = ds1682_eeprom_read, 196 .write = ds1682_eeprom_write, 197 }; 198 199 /* 200 * Called when a ds1682 device is matched with this driver 201 */ 202 static int ds1682_probe(struct i2c_client *client, 203 const struct i2c_device_id *id) 204 { 205 int rc; 206 207 if (!i2c_check_functionality(client->adapter, 208 I2C_FUNC_SMBUS_I2C_BLOCK)) { 209 dev_err(&client->dev, "i2c bus does not support the ds1682\n"); 210 rc = -ENODEV; 211 goto exit; 212 } 213 214 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group); 215 if (rc) 216 goto exit; 217 218 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 219 if (rc) 220 goto exit_bin_attr; 221 222 return 0; 223 224 exit_bin_attr: 225 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 226 exit: 227 return rc; 228 } 229 230 static int ds1682_remove(struct i2c_client *client) 231 { 232 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 233 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 234 return 0; 235 } 236 237 static const struct i2c_device_id ds1682_id[] = { 238 { "ds1682", 0 }, 239 { } 240 }; 241 MODULE_DEVICE_TABLE(i2c, ds1682_id); 242 243 static struct i2c_driver ds1682_driver = { 244 .driver = { 245 .name = "ds1682", 246 }, 247 .probe = ds1682_probe, 248 .remove = ds1682_remove, 249 .id_table = ds1682_id, 250 }; 251 252 module_i2c_driver(ds1682_driver); 253 254 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); 255 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver"); 256 MODULE_LICENSE("GPL"); 257