1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Dallas Semiconductor DS1682 Elapsed Time Recorder device driver 4 * 5 * Written by: Grant Likely <grant.likely@secretlab.ca> 6 * 7 * Copyright (C) 2007 Secret Lab Technologies Ltd. 8 */ 9 10 /* 11 * The DS1682 elapsed timer recorder is a simple device that implements 12 * one elapsed time counter, one event counter, an alarm signal and 10 13 * bytes of general purpose EEPROM. 14 * 15 * This driver provides access to the DS1682 counters and user data via 16 * the sysfs. The following attributes are added to the device node: 17 * elapsed_time (u32): Total elapsed event time in ms resolution 18 * alarm_time (u32): When elapsed time exceeds the value in alarm_time, 19 * then the alarm pin is asserted. 20 * event_count (u16): number of times the event pin has gone low. 21 * eeprom (u8[10]): general purpose EEPROM 22 * 23 * Counter registers and user data are both read/write unless the device 24 * has been write protected. This driver does not support turning off write 25 * protection. Once write protection is turned on, it is impossible to 26 * turn it off again, so I have left the feature out of this driver to avoid 27 * accidental enabling, but it is trivial to add write protect support. 28 * 29 */ 30 31 #include <linux/module.h> 32 #include <linux/i2c.h> 33 #include <linux/string.h> 34 #include <linux/list.h> 35 #include <linux/sysfs.h> 36 #include <linux/ctype.h> 37 #include <linux/hwmon-sysfs.h> 38 39 /* Device registers */ 40 #define DS1682_REG_CONFIG 0x00 41 #define DS1682_REG_ALARM 0x01 42 #define DS1682_REG_ELAPSED 0x05 43 #define DS1682_REG_EVT_CNTR 0x09 44 #define DS1682_REG_EEPROM 0x0b 45 #define DS1682_REG_RESET 0x1d 46 #define DS1682_REG_WRITE_DISABLE 0x1e 47 #define DS1682_REG_WRITE_MEM_DISABLE 0x1f 48 49 #define DS1682_EEPROM_SIZE 10 50 51 /* 52 * Generic counter attributes 53 */ 54 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr, 55 char *buf) 56 { 57 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 58 struct i2c_client *client = to_i2c_client(dev); 59 unsigned long long val, check; 60 __le32 val_le = 0; 61 int rc; 62 63 dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name); 64 65 /* Read the register */ 66 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr, 67 (u8 *)&val_le); 68 if (rc < 0) 69 return -EIO; 70 71 val = le32_to_cpu(val_le); 72 73 if (sattr->index == DS1682_REG_ELAPSED) { 74 int retries = 5; 75 76 /* Detect and retry when a tick occurs mid-read */ 77 do { 78 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, 79 sattr->nr, 80 (u8 *)&val_le); 81 if (rc < 0 || retries <= 0) 82 return -EIO; 83 84 check = val; 85 val = le32_to_cpu(val_le); 86 retries--; 87 } while (val != check && val != (check + 1)); 88 } 89 90 /* Format the output string and return # of bytes 91 * Special case: the 32 bit regs are time values with 1/4s 92 * resolution, scale them up to milliseconds 93 */ 94 return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val); 95 } 96 97 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr, 98 const char *buf, size_t count) 99 { 100 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 101 struct i2c_client *client = to_i2c_client(dev); 102 u64 val; 103 __le32 val_le; 104 int rc; 105 106 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name); 107 108 /* Decode input */ 109 rc = kstrtoull(buf, 0, &val); 110 if (rc < 0) { 111 dev_dbg(dev, "input string not a number\n"); 112 return -EINVAL; 113 } 114 115 /* Special case: the 32 bit regs are time values with 1/4s 116 * resolution, scale input down to quarter-seconds */ 117 if (sattr->nr == 4) 118 do_div(val, 250); 119 120 /* write out the value */ 121 val_le = cpu_to_le32(val); 122 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr, 123 (u8 *) & val_le); 124 if (rc < 0) { 125 dev_err(dev, "register write failed; reg=0x%x, size=%i\n", 126 sattr->index, sattr->nr); 127 return -EIO; 128 } 129 130 return count; 131 } 132 133 /* 134 * Simple register attributes 135 */ 136 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show, 137 ds1682_store, 4, DS1682_REG_ELAPSED); 138 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show, 139 ds1682_store, 4, DS1682_REG_ALARM); 140 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show, 141 ds1682_store, 2, DS1682_REG_EVT_CNTR); 142 143 static const struct attribute_group ds1682_group = { 144 .attrs = (struct attribute *[]) { 145 &sensor_dev_attr_elapsed_time.dev_attr.attr, 146 &sensor_dev_attr_alarm_time.dev_attr.attr, 147 &sensor_dev_attr_event_count.dev_attr.attr, 148 NULL, 149 }, 150 }; 151 152 /* 153 * User data attribute 154 */ 155 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj, 156 struct bin_attribute *attr, 157 char *buf, loff_t off, size_t count) 158 { 159 struct i2c_client *client = kobj_to_i2c_client(kobj); 160 int rc; 161 162 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n", 163 buf, off, count); 164 165 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off, 166 count, buf); 167 if (rc < 0) 168 return -EIO; 169 170 return count; 171 } 172 173 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj, 174 struct bin_attribute *attr, 175 char *buf, loff_t off, size_t count) 176 { 177 struct i2c_client *client = kobj_to_i2c_client(kobj); 178 179 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n", 180 buf, off, count); 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 const 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 void 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 } 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 const struct of_device_id ds1682_of_match[] = { 244 { .compatible = "dallas,ds1682", }, 245 {} 246 }; 247 MODULE_DEVICE_TABLE(of, ds1682_of_match); 248 249 static struct i2c_driver ds1682_driver = { 250 .driver = { 251 .name = "ds1682", 252 .of_match_table = ds1682_of_match, 253 }, 254 .probe = ds1682_probe, 255 .remove = ds1682_remove, 256 .id_table = ds1682_id, 257 }; 258 259 module_i2c_driver(ds1682_driver); 260 261 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); 262 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver"); 263 MODULE_LICENSE("GPL"); 264