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 file *filp, struct kobject *kobj, 144 struct bin_attribute *attr, 145 char *buf, loff_t off, size_t count) 146 { 147 struct i2c_client *client = kobj_to_i2c_client(kobj); 148 int rc; 149 150 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n", 151 buf, off, count); 152 153 if (off >= DS1682_EEPROM_SIZE) 154 return 0; 155 156 if (off + count > DS1682_EEPROM_SIZE) 157 count = DS1682_EEPROM_SIZE - off; 158 159 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off, 160 count, buf); 161 if (rc < 0) 162 return -EIO; 163 164 return count; 165 } 166 167 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj, 168 struct bin_attribute *attr, 169 char *buf, loff_t off, size_t count) 170 { 171 struct i2c_client *client = kobj_to_i2c_client(kobj); 172 173 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n", 174 buf, off, count); 175 176 if (off >= DS1682_EEPROM_SIZE) 177 return -ENOSPC; 178 179 if (off + count > DS1682_EEPROM_SIZE) 180 count = DS1682_EEPROM_SIZE - off; 181 182 /* Write out to the device */ 183 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off, 184 count, buf) < 0) 185 return -EIO; 186 187 return count; 188 } 189 190 static struct bin_attribute ds1682_eeprom_attr = { 191 .attr = { 192 .name = "eeprom", 193 .mode = S_IRUGO | S_IWUSR, 194 }, 195 .size = DS1682_EEPROM_SIZE, 196 .read = ds1682_eeprom_read, 197 .write = ds1682_eeprom_write, 198 }; 199 200 /* 201 * Called when a ds1682 device is matched with this driver 202 */ 203 static int ds1682_probe(struct i2c_client *client, 204 const struct i2c_device_id *id) 205 { 206 int rc; 207 208 if (!i2c_check_functionality(client->adapter, 209 I2C_FUNC_SMBUS_I2C_BLOCK)) { 210 dev_err(&client->dev, "i2c bus does not support the ds1682\n"); 211 rc = -ENODEV; 212 goto exit; 213 } 214 215 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group); 216 if (rc) 217 goto exit; 218 219 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 220 if (rc) 221 goto exit_bin_attr; 222 223 return 0; 224 225 exit_bin_attr: 226 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 227 exit: 228 return rc; 229 } 230 231 static int ds1682_remove(struct i2c_client *client) 232 { 233 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 234 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 235 return 0; 236 } 237 238 static const struct i2c_device_id ds1682_id[] = { 239 { "ds1682", 0 }, 240 { } 241 }; 242 MODULE_DEVICE_TABLE(i2c, ds1682_id); 243 244 static struct i2c_driver ds1682_driver = { 245 .driver = { 246 .name = "ds1682", 247 }, 248 .probe = ds1682_probe, 249 .remove = ds1682_remove, 250 .id_table = ds1682_id, 251 }; 252 253 module_i2c_driver(ds1682_driver); 254 255 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); 256 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver"); 257 MODULE_LICENSE("GPL"); 258