drivers/w1/slaves/w1_ds2438.c

   1 /*
   2  * 1-Wire implementation for the ds2438 chip
   3  *
   4  * Copyright (c) 2017 Mariusz Bialonczyk <manio@skyboo.net>
   5  *
   6  * This source code is licensed under the GNU General Public License,
   7  * Version 2. See the file COPYING for more details.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/device.h>
  13 #include <linux/types.h>
  14 #include <linux/delay.h>
  15
  16 #include <linux/w1.h>
  17
  18 #define W1_FAMILY_DS2438                0x26
  19
  20 #define W1_DS2438_RETRIES               3
  21
  22 /* Memory commands */
  23 #define W1_DS2438_READ_SCRATCH          0xBE
  24 #define W1_DS2438_WRITE_SCRATCH         0x4E
  25 #define W1_DS2438_COPY_SCRATCH          0x48
  26 #define W1_DS2438_RECALL_MEMORY         0xB8
  27 /* Register commands */
  28 #define W1_DS2438_CONVERT_TEMP          0x44
  29 #define W1_DS2438_CONVERT_VOLTAGE       0xB4
  30
  31 #define DS2438_PAGE_SIZE                8
  32 #define DS2438_ADC_INPUT_VAD            0
  33 #define DS2438_ADC_INPUT_VDD            1
  34 #define DS2438_MAX_CONVERSION_TIME      10              /* ms */
  35
  36 /* Page #0 definitions */
  37 #define DS2438_STATUS_REG               0x00            /* Status/Configuration Register */
  38 #define DS2438_STATUS_IAD               (1 << 0)        /* Current A/D Control Bit */
  39 #define DS2438_STATUS_CA                (1 << 1)        /* Current Accumulator Configuration */
  40 #define DS2438_STATUS_EE                (1 << 2)        /* Current Accumulator Shadow Selector bit */
  41 #define DS2438_STATUS_AD                (1 << 3)        /* Voltage A/D Input Select Bit */
  42 #define DS2438_STATUS_TB                (1 << 4)        /* Temperature Busy Flag */
  43 #define DS2438_STATUS_NVB               (1 << 5)        /* Nonvolatile Memory Busy Flag */
  44 #define DS2438_STATUS_ADB               (1 << 6)        /* A/D Converter Busy Flag */
  45
  46 #define DS2438_TEMP_LSB                 0x01
  47 #define DS2438_TEMP_MSB                 0x02
  48 #define DS2438_VOLTAGE_LSB              0x03
  49 #define DS2438_VOLTAGE_MSB              0x04
  50 #define DS2438_CURRENT_LSB              0x05
  51 #define DS2438_CURRENT_MSB              0x06
  52 #define DS2438_THRESHOLD                0x07
  53
  54 static int w1_ds2438_get_page(struct w1_slave *sl, int pageno, u8 *buf)
  55 {
  56         unsigned int retries = W1_DS2438_RETRIES;
  57         u8 w1_buf[2];
  58         u8 crc;
  59         size_t count;
  60
  61         while (retries--) {
  62                 crc = 0;
  63
  64                 if (w1_reset_select_slave(sl))
  65                         continue;
  66                 w1_buf[0] = W1_DS2438_RECALL_MEMORY;
  67                 w1_buf[1] = 0x00;
  68                 w1_write_block(sl->master, w1_buf, 2);
  69
  70                 if (w1_reset_select_slave(sl))
  71                         continue;
  72                 w1_buf[0] = W1_DS2438_READ_SCRATCH;
  73                 w1_buf[1] = 0x00;
  74                 w1_write_block(sl->master, w1_buf, 2);
  75
  76                 count = w1_read_block(sl->master, buf, DS2438_PAGE_SIZE + 1);
  77                 if (count == DS2438_PAGE_SIZE + 1) {
  78                         crc = w1_calc_crc8(buf, DS2438_PAGE_SIZE);
  79
  80                         /* check for correct CRC */
  81                         if ((u8)buf[DS2438_PAGE_SIZE] == crc)
  82                                 return 0;
  83                 }
  84         }
  85         return -1;
  86 }
  87
  88 static int w1_ds2438_get_temperature(struct w1_slave *sl, int16_t *temperature)
  89 {
  90         unsigned int retries = W1_DS2438_RETRIES;
  91         u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
  92         unsigned int tm = DS2438_MAX_CONVERSION_TIME;
  93         unsigned long sleep_rem;
  94         int ret;
  95
  96         mutex_lock(&sl->master->bus_mutex);
  97
  98         while (retries--) {
  99                 if (w1_reset_select_slave(sl))
 100                         continue;
 101                 w1_write_8(sl->master, W1_DS2438_CONVERT_TEMP);
 102
 103                 mutex_unlock(&sl->master->bus_mutex);
 104                 sleep_rem = msleep_interruptible(tm);
 105                 if (sleep_rem != 0) {
 106                         ret = -1;
 107                         goto post_unlock;
 108                 }
 109
 110                 if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0) {
 111                         ret = -1;
 112                         goto post_unlock;
 113                 }
 114
 115                 break;
 116         }
 117
 118         if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
 119                 *temperature = (((int16_t) w1_buf[DS2438_TEMP_MSB]) << 8) | ((uint16_t) w1_buf[DS2438_TEMP_LSB]);
 120                 ret = 0;
 121         } else
 122                 ret = -1;
 123
 124         mutex_unlock(&sl->master->bus_mutex);
 125
 126 post_unlock:
 127         return ret;
 128 }
 129
 130 static int w1_ds2438_change_config_bit(struct w1_slave *sl, u8 mask, u8 value)
 131 {
 132         unsigned int retries = W1_DS2438_RETRIES;
 133         u8 w1_buf[3];
 134         u8 status;
 135         int perform_write = 0;
 136
 137         while (retries--) {
 138                 if (w1_reset_select_slave(sl))
 139                         continue;
 140                 w1_buf[0] = W1_DS2438_RECALL_MEMORY;
 141                 w1_buf[1] = 0x00;
 142                 w1_write_block(sl->master, w1_buf, 2);
 143
 144                 if (w1_reset_select_slave(sl))
 145                         continue;
 146                 w1_buf[0] = W1_DS2438_READ_SCRATCH;
 147                 w1_buf[1] = 0x00;
 148                 w1_write_block(sl->master, w1_buf, 2);
 149
 150                 /* reading one byte of result */
 151                 status = w1_read_8(sl->master);
 152
 153                 /* if bit0=1, set a value to a mask for easy compare */
 154                 if (value)
 155                         value = mask;
 156
 157                 if ((status & mask) == value)
 158                         return 0;       /* already set as requested */
 159                 else {
 160                         /* changing bit */
 161                         status ^= mask;
 162                         perform_write = 1;
 163                 }
 164                 break;
 165         }
 166
 167         if (perform_write) {
 168                 retries = W1_DS2438_RETRIES;
 169                 while (retries--) {
 170                         if (w1_reset_select_slave(sl))
 171                                 continue;
 172                         w1_buf[0] = W1_DS2438_WRITE_SCRATCH;
 173                         w1_buf[1] = 0x00;
 174                         w1_buf[2] = status;
 175                         w1_write_block(sl->master, w1_buf, 3);
 176
 177                         if (w1_reset_select_slave(sl))
 178                                 continue;
 179                         w1_buf[0] = W1_DS2438_COPY_SCRATCH;
 180                         w1_buf[1] = 0x00;
 181                         w1_write_block(sl->master, w1_buf, 2);
 182
 183                         return 0;
 184                 }
 185         }
 186         return -1;
 187 }
 188
 189 static uint16_t w1_ds2438_get_voltage(struct w1_slave *sl,
 190                                       int adc_input, uint16_t *voltage)
 191 {
 192         unsigned int retries = W1_DS2438_RETRIES;
 193         u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
 194         unsigned int tm = DS2438_MAX_CONVERSION_TIME;
 195         unsigned long sleep_rem;
 196         int ret;
 197
 198         mutex_lock(&sl->master->bus_mutex);
 199
 200         if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_AD, adc_input)) {
 201                 ret = -1;
 202                 goto pre_unlock;
 203         }
 204
 205         while (retries--) {
 206                 if (w1_reset_select_slave(sl))
 207                         continue;
 208                 w1_write_8(sl->master, W1_DS2438_CONVERT_VOLTAGE);
 209
 210                 mutex_unlock(&sl->master->bus_mutex);
 211                 sleep_rem = msleep_interruptible(tm);
 212                 if (sleep_rem != 0) {
 213                         ret = -1;
 214                         goto post_unlock;
 215                 }
 216
 217                 if (mutex_lock_interruptible(&sl->master->bus_mutex) != 0) {
 218                         ret = -1;
 219                         goto post_unlock;
 220                 }
 221
 222                 break;
 223         }
 224
 225         if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
 226                 *voltage = (((uint16_t) w1_buf[DS2438_VOLTAGE_MSB]) << 8) | ((uint16_t) w1_buf[DS2438_VOLTAGE_LSB]);
 227                 ret = 0;
 228         } else
 229                 ret = -1;
 230
 231 pre_unlock:
 232         mutex_unlock(&sl->master->bus_mutex);
 233
 234 post_unlock:
 235         return ret;
 236 }
 237
 238 static ssize_t iad_write(struct file *filp, struct kobject *kobj,
 239                          struct bin_attribute *bin_attr, char *buf,
 240                          loff_t off, size_t count)
 241 {
 242         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 243         int ret;
 244
 245         if (count != 1 || off != 0)
 246                 return -EFAULT;
 247
 248         mutex_lock(&sl->master->bus_mutex);
 249
 250         if (w1_ds2438_change_config_bit(sl, DS2438_STATUS_IAD, *buf & 0x01) == 0)
 251                 ret = 1;
 252         else
 253                 ret = -EIO;
 254
 255         mutex_unlock(&sl->master->bus_mutex);
 256
 257         return ret;
 258 }
 259
 260 static ssize_t page0_read(struct file *filp, struct kobject *kobj,
 261                           struct bin_attribute *bin_attr, char *buf,
 262                           loff_t off, size_t count)
 263 {
 264         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 265         int ret;
 266         u8 w1_buf[DS2438_PAGE_SIZE + 1 /*for CRC*/];
 267
 268         if (off != 0)
 269                 return 0;
 270         if (!buf)
 271                 return -EINVAL;
 272
 273         mutex_lock(&sl->master->bus_mutex);
 274
 275         if (w1_ds2438_get_page(sl, 0, w1_buf) == 0) {
 276                 memcpy(buf, &w1_buf, DS2438_PAGE_SIZE);
 277                 ret = DS2438_PAGE_SIZE;
 278         } else
 279                 ret = -EIO;
 280
 281         mutex_unlock(&sl->master->bus_mutex);
 282
 283         return ret;
 284 }
 285
 286 static ssize_t temperature_read(struct file *filp, struct kobject *kobj,
 287                                 struct bin_attribute *bin_attr, char *buf,
 288                                 loff_t off, size_t count)
 289 {
 290         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 291         int ret;
 292         ssize_t c = PAGE_SIZE;
 293         int16_t temp;
 294
 295         if (off != 0)
 296                 return 0;
 297         if (!buf)
 298                 return -EINVAL;
 299
 300         if (w1_ds2438_get_temperature(sl, &temp) == 0) {
 301                 c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", temp);
 302                 ret = PAGE_SIZE - c;
 303         } else
 304                 ret = -EIO;
 305
 306         return ret;
 307 }
 308
 309 static ssize_t vad_read(struct file *filp, struct kobject *kobj,
 310                         struct bin_attribute *bin_attr, char *buf,
 311                         loff_t off, size_t count)
 312 {
 313         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 314         int ret;
 315         ssize_t c = PAGE_SIZE;
 316         uint16_t voltage;
 317
 318         if (off != 0)
 319                 return 0;
 320         if (!buf)
 321                 return -EINVAL;
 322
 323         if (w1_ds2438_get_voltage(sl, DS2438_ADC_INPUT_VAD, &voltage) == 0) {
 324                 c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", voltage);
 325                 ret = PAGE_SIZE - c;
 326         } else
 327                 ret = -EIO;
 328
 329         return ret;
 330 }
 331
 332 static ssize_t vdd_read(struct file *filp, struct kobject *kobj,
 333                         struct bin_attribute *bin_attr, char *buf,
 334                         loff_t off, size_t count)
 335 {
 336         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 337         int ret;
 338         ssize_t c = PAGE_SIZE;
 339         uint16_t voltage;
 340
 341         if (off != 0)
 342                 return 0;
 343         if (!buf)
 344                 return -EINVAL;
 345
 346         if (w1_ds2438_get_voltage(sl, DS2438_ADC_INPUT_VDD, &voltage) == 0) {
 347                 c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", voltage);
 348                 ret = PAGE_SIZE - c;
 349         } else
 350                 ret = -EIO;
 351
 352         return ret;
 353 }
 354
 355 static BIN_ATTR(iad, S_IRUGO | S_IWUSR | S_IWGRP, NULL, iad_write, 1);
 356 static BIN_ATTR_RO(page0, DS2438_PAGE_SIZE);
 357 static BIN_ATTR_RO(temperature, 0/* real length varies */);
 358 static BIN_ATTR_RO(vad, 0/* real length varies */);
 359 static BIN_ATTR_RO(vdd, 0/* real length varies */);
 360
 361 static struct bin_attribute *w1_ds2438_bin_attrs[] = {
 362         &bin_attr_iad,
 363         &bin_attr_page0,
 364         &bin_attr_temperature,
 365         &bin_attr_vad,
 366         &bin_attr_vdd,
 367         NULL,
 368 };
 369
 370 static const struct attribute_group w1_ds2438_group = {
 371         .bin_attrs = w1_ds2438_bin_attrs,
 372 };
 373
 374 static const struct attribute_group *w1_ds2438_groups[] = {
 375         &w1_ds2438_group,
 376         NULL,
 377 };
 378
 379 static struct w1_family_ops w1_ds2438_fops = {
 380         .groups         = w1_ds2438_groups,
 381 };
 382
 383 static struct w1_family w1_ds2438_family = {
 384         .fid = W1_FAMILY_DS2438,
 385         .fops = &w1_ds2438_fops,
 386 };
 387 module_w1_family(w1_ds2438_family);
 388
 389 MODULE_LICENSE("GPL");
 390 MODULE_AUTHOR("Mariusz Bialonczyk <manio@skyboo.net>");
 391 MODULE_DESCRIPTION("1-wire driver for Maxim/Dallas DS2438 Smart Battery Monitor");
 392 MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2438));