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/nvmem-provider.h> 36 #include <linux/sysfs.h> 37 #include <linux/ctype.h> 38 #include <linux/hwmon-sysfs.h> 39 40 /* Device registers */ 41 #define DS1682_REG_CONFIG 0x00 42 #define DS1682_REG_ALARM 0x01 43 #define DS1682_REG_ELAPSED 0x05 44 #define DS1682_REG_EVT_CNTR 0x09 45 #define DS1682_REG_EEPROM 0x0b 46 #define DS1682_REG_RESET 0x1d 47 #define DS1682_REG_WRITE_DISABLE 0x1e 48 #define DS1682_REG_WRITE_MEM_DISABLE 0x1f 49 50 #define DS1682_EEPROM_SIZE 10 51 52 /* 53 * Generic counter attributes 54 */ 55 static ssize_t ds1682_show(struct device *dev, struct device_attribute *attr, 56 char *buf) 57 { 58 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 59 struct i2c_client *client = to_i2c_client(dev); 60 unsigned long long val, check; 61 __le32 val_le = 0; 62 int rc; 63 64 dev_dbg(dev, "ds1682_show() called on %s\n", attr->attr.name); 65 66 /* Read the register */ 67 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, sattr->nr, 68 (u8 *)&val_le); 69 if (rc < 0) 70 return -EIO; 71 72 val = le32_to_cpu(val_le); 73 74 if (sattr->index == DS1682_REG_ELAPSED) { 75 int retries = 5; 76 77 /* Detect and retry when a tick occurs mid-read */ 78 do { 79 rc = i2c_smbus_read_i2c_block_data(client, sattr->index, 80 sattr->nr, 81 (u8 *)&val_le); 82 if (rc < 0 || retries <= 0) 83 return -EIO; 84 85 check = val; 86 val = le32_to_cpu(val_le); 87 retries--; 88 } while (val != check && val != (check + 1)); 89 } 90 91 /* Format the output string and return # of bytes 92 * Special case: the 32 bit regs are time values with 1/4s 93 * resolution, scale them up to milliseconds 94 */ 95 return sprintf(buf, "%llu\n", (sattr->nr == 4) ? (val * 250) : val); 96 } 97 98 static ssize_t ds1682_store(struct device *dev, struct device_attribute *attr, 99 const char *buf, size_t count) 100 { 101 struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr); 102 struct i2c_client *client = to_i2c_client(dev); 103 u64 val; 104 __le32 val_le; 105 int rc; 106 107 dev_dbg(dev, "ds1682_store() called on %s\n", attr->attr.name); 108 109 /* Decode input */ 110 rc = kstrtoull(buf, 0, &val); 111 if (rc < 0) { 112 dev_dbg(dev, "input string not a number\n"); 113 return -EINVAL; 114 } 115 116 /* Special case: the 32 bit regs are time values with 1/4s 117 * resolution, scale input down to quarter-seconds */ 118 if (sattr->nr == 4) 119 do_div(val, 250); 120 121 /* write out the value */ 122 val_le = cpu_to_le32(val); 123 rc = i2c_smbus_write_i2c_block_data(client, sattr->index, sattr->nr, 124 (u8 *) & val_le); 125 if (rc < 0) { 126 dev_err(dev, "register write failed; reg=0x%x, size=%i\n", 127 sattr->index, sattr->nr); 128 return -EIO; 129 } 130 131 return count; 132 } 133 134 /* 135 * Simple register attributes 136 */ 137 static SENSOR_DEVICE_ATTR_2(elapsed_time, S_IRUGO | S_IWUSR, ds1682_show, 138 ds1682_store, 4, DS1682_REG_ELAPSED); 139 static SENSOR_DEVICE_ATTR_2(alarm_time, S_IRUGO | S_IWUSR, ds1682_show, 140 ds1682_store, 4, DS1682_REG_ALARM); 141 static SENSOR_DEVICE_ATTR_2(event_count, S_IRUGO | S_IWUSR, ds1682_show, 142 ds1682_store, 2, DS1682_REG_EVT_CNTR); 143 144 static const struct attribute_group ds1682_group = { 145 .attrs = (struct attribute *[]) { 146 &sensor_dev_attr_elapsed_time.dev_attr.attr, 147 &sensor_dev_attr_alarm_time.dev_attr.attr, 148 &sensor_dev_attr_event_count.dev_attr.attr, 149 NULL, 150 }, 151 }; 152 153 /* 154 * User data attribute 155 */ 156 static ssize_t ds1682_eeprom_read(struct file *filp, struct kobject *kobj, 157 struct bin_attribute *attr, 158 char *buf, loff_t off, size_t count) 159 { 160 struct i2c_client *client = kobj_to_i2c_client(kobj); 161 int rc; 162 163 dev_dbg(&client->dev, "ds1682_eeprom_read(p=%p, off=%lli, c=%zi)\n", 164 buf, off, count); 165 166 rc = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + off, 167 count, buf); 168 if (rc < 0) 169 return -EIO; 170 171 return count; 172 } 173 174 static ssize_t ds1682_eeprom_write(struct file *filp, struct kobject *kobj, 175 struct bin_attribute *attr, 176 char *buf, loff_t off, size_t count) 177 { 178 struct i2c_client *client = kobj_to_i2c_client(kobj); 179 180 dev_dbg(&client->dev, "ds1682_eeprom_write(p=%p, off=%lli, c=%zi)\n", 181 buf, off, count); 182 183 /* Write out to the device */ 184 if (i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + off, 185 count, buf) < 0) 186 return -EIO; 187 188 return count; 189 } 190 191 static const struct bin_attribute ds1682_eeprom_attr = { 192 .attr = { 193 .name = "eeprom", 194 .mode = S_IRUGO | S_IWUSR, 195 }, 196 .size = DS1682_EEPROM_SIZE, 197 .read = ds1682_eeprom_read, 198 .write = ds1682_eeprom_write, 199 }; 200 201 static int ds1682_nvmem_read(void *priv, unsigned int offset, void *val, 202 size_t bytes) 203 { 204 struct i2c_client *client = priv; 205 int ret; 206 207 ret = i2c_smbus_read_i2c_block_data(client, DS1682_REG_EEPROM + offset, 208 bytes, val); 209 return ret < 0 ? ret : 0; 210 } 211 212 static int ds1682_nvmem_write(void *priv, unsigned int offset, void *val, 213 size_t bytes) 214 { 215 struct i2c_client *client = priv; 216 int ret; 217 218 ret = i2c_smbus_write_i2c_block_data(client, DS1682_REG_EEPROM + offset, 219 bytes, val); 220 return ret < 0 ? ret : 0; 221 } 222 223 /* 224 * Called when a ds1682 device is matched with this driver 225 */ 226 static int ds1682_probe(struct i2c_client *client) 227 { 228 struct nvmem_config config = { 229 .dev = &client->dev, 230 .owner = THIS_MODULE, 231 .type = NVMEM_TYPE_EEPROM, 232 .reg_read = ds1682_nvmem_read, 233 .reg_write = ds1682_nvmem_write, 234 .size = DS1682_EEPROM_SIZE, 235 .priv = client, 236 }; 237 struct nvmem_device *nvmem; 238 int rc; 239 240 if (!i2c_check_functionality(client->adapter, 241 I2C_FUNC_SMBUS_I2C_BLOCK)) { 242 dev_err(&client->dev, "i2c bus does not support the ds1682\n"); 243 rc = -ENODEV; 244 goto exit; 245 } 246 247 nvmem = devm_nvmem_register(&client->dev, &config); 248 if (IS_ENABLED(CONFIG_NVMEM) && IS_ERR(nvmem)) 249 return PTR_ERR(nvmem); 250 251 rc = sysfs_create_group(&client->dev.kobj, &ds1682_group); 252 if (rc) 253 goto exit; 254 255 rc = sysfs_create_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 256 if (rc) 257 goto exit_bin_attr; 258 259 return 0; 260 261 exit_bin_attr: 262 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 263 exit: 264 return rc; 265 } 266 267 static void ds1682_remove(struct i2c_client *client) 268 { 269 sysfs_remove_bin_file(&client->dev.kobj, &ds1682_eeprom_attr); 270 sysfs_remove_group(&client->dev.kobj, &ds1682_group); 271 } 272 273 static const struct i2c_device_id ds1682_id[] = { 274 { "ds1682" }, 275 { } 276 }; 277 MODULE_DEVICE_TABLE(i2c, ds1682_id); 278 279 static const struct of_device_id ds1682_of_match[] = { 280 { .compatible = "dallas,ds1682", }, 281 {} 282 }; 283 MODULE_DEVICE_TABLE(of, ds1682_of_match); 284 285 static struct i2c_driver ds1682_driver = { 286 .driver = { 287 .name = "ds1682", 288 .of_match_table = ds1682_of_match, 289 }, 290 .probe = ds1682_probe, 291 .remove = ds1682_remove, 292 .id_table = ds1682_id, 293 }; 294 295 module_i2c_driver(ds1682_driver); 296 297 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>"); 298 MODULE_DESCRIPTION("DS1682 Elapsed Time Indicator driver"); 299 MODULE_LICENSE("GPL"); 300