drivers/rtc/rtc-bq32k.c

   1 /*
   2  * Driver for TI BQ32000 RTC.
   3  *
   4  * Copyright (C) 2009 Semihalf.
   5  * Copyright (C) 2014 Pavel Machek <pavel@denx.de>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * You can get hardware description at
  12  * http://www.ti.com/lit/ds/symlink/bq32000.pdf
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/i2c.h>
  17 #include <linux/rtc.h>
  18 #include <linux/init.h>
  19 #include <linux/errno.h>
  20 #include <linux/bcd.h>
  21
  22 #define BQ32K_SECONDS           0x00    /* Seconds register address */
  23 #define BQ32K_SECONDS_MASK      0x7F    /* Mask over seconds value */
  24 #define BQ32K_STOP              0x80    /* Oscillator Stop flat */
  25
  26 #define BQ32K_MINUTES           0x01    /* Minutes register address */
  27 #define BQ32K_MINUTES_MASK      0x7F    /* Mask over minutes value */
  28 #define BQ32K_OF                0x80    /* Oscillator Failure flag */
  29
  30 #define BQ32K_HOURS_MASK        0x3F    /* Mask over hours value */
  31 #define BQ32K_CENT              0x40    /* Century flag */
  32 #define BQ32K_CENT_EN           0x80    /* Century flag enable bit */
  33
  34 #define BQ32K_CALIBRATION       0x07    /* CAL_CFG1, calibration and control */
  35 #define BQ32K_TCH2              0x08    /* Trickle charge enable */
  36 #define BQ32K_CFG2              0x09    /* Trickle charger control */
  37 #define BQ32K_TCFE              BIT(6)  /* Trickle charge FET bypass */
  38
  39 struct bq32k_regs {
  40         uint8_t         seconds;
  41         uint8_t         minutes;
  42         uint8_t         cent_hours;
  43         uint8_t         day;
  44         uint8_t         date;
  45         uint8_t         month;
  46         uint8_t         years;
  47 };
  48
  49 static struct i2c_driver bq32k_driver;
  50
  51 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
  52 {
  53         struct i2c_client *client = to_i2c_client(dev);
  54         struct i2c_msg msgs[] = {
  55                 {
  56                         .addr = client->addr,
  57                         .flags = 0,
  58                         .len = 1,
  59                         .buf = &off,
  60                 }, {
  61                         .addr = client->addr,
  62                         .flags = I2C_M_RD,
  63                         .len = len,
  64                         .buf = data,
  65                 }
  66         };
  67
  68         if (i2c_transfer(client->adapter, msgs, 2) == 2)
  69                 return 0;
  70
  71         return -EIO;
  72 }
  73
  74 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
  75 {
  76         struct i2c_client *client = to_i2c_client(dev);
  77         uint8_t buffer[len + 1];
  78
  79         buffer[0] = off;
  80         memcpy(&buffer[1], data, len);
  81
  82         if (i2c_master_send(client, buffer, len + 1) == len + 1)
  83                 return 0;
  84
  85         return -EIO;
  86 }
  87
  88 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
  89 {
  90         struct bq32k_regs regs;
  91         int error;
  92
  93         error = bq32k_read(dev, &regs, 0, sizeof(regs));
  94         if (error)
  95                 return error;
  96
  97         /*
  98          * In case of oscillator failure, the register contents should be
  99          * considered invalid. The flag is cleared the next time the RTC is set.
 100          */
 101         if (regs.minutes & BQ32K_OF)
 102                 return -EINVAL;
 103
 104         tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
 105         tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
 106         tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
 107         tm->tm_mday = bcd2bin(regs.date);
 108         tm->tm_wday = bcd2bin(regs.day) - 1;
 109         tm->tm_mon = bcd2bin(regs.month) - 1;
 110         tm->tm_year = bcd2bin(regs.years) +
 111                                 ((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
 112
 113         return rtc_valid_tm(tm);
 114 }
 115
 116 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
 117 {
 118         struct bq32k_regs regs;
 119
 120         regs.seconds = bin2bcd(tm->tm_sec);
 121         regs.minutes = bin2bcd(tm->tm_min);
 122         regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
 123         regs.day = bin2bcd(tm->tm_wday + 1);
 124         regs.date = bin2bcd(tm->tm_mday);
 125         regs.month = bin2bcd(tm->tm_mon + 1);
 126
 127         if (tm->tm_year >= 100) {
 128                 regs.cent_hours |= BQ32K_CENT;
 129                 regs.years = bin2bcd(tm->tm_year - 100);
 130         } else
 131                 regs.years = bin2bcd(tm->tm_year);
 132
 133         return bq32k_write(dev, &regs, 0, sizeof(regs));
 134 }
 135
 136 static const struct rtc_class_ops bq32k_rtc_ops = {
 137         .read_time      = bq32k_rtc_read_time,
 138         .set_time       = bq32k_rtc_set_time,
 139 };
 140
 141 static int trickle_charger_of_init(struct device *dev, struct device_node *node)
 142 {
 143         unsigned char reg;
 144         int error;
 145         u32 ohms = 0;
 146
 147         if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
 148                 return 0;
 149
 150         switch (ohms) {
 151         case 180+940:
 152                 /*
 153                  * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
 154                  * over diode and 940ohm resistor)
 155                  */
 156
 157                 if (of_property_read_bool(node, "trickle-diode-disable")) {
 158                         dev_err(dev, "diode and resistor mismatch\n");
 159                         return -EINVAL;
 160                 }
 161                 reg = 0x05;
 162                 break;
 163
 164         case 180+20000:
 165                 /* diode disabled */
 166
 167                 if (!of_property_read_bool(node, "trickle-diode-disable")) {
 168                         dev_err(dev, "bq32k: diode and resistor mismatch\n");
 169                         return -EINVAL;
 170                 }
 171                 reg = 0x45;
 172                 break;
 173
 174         default:
 175                 dev_err(dev, "invalid resistor value (%d)\n", ohms);
 176                 return -EINVAL;
 177         }
 178
 179         error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 180         if (error)
 181                 return error;
 182
 183         reg = 0x20;
 184         error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);
 185         if (error)
 186                 return error;
 187
 188         dev_info(dev, "Enabled trickle RTC battery charge.\n");
 189         return 0;
 190 }
 191
 192 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
 193                                                struct device_attribute *attr,
 194                                                char *buf)
 195 {
 196         int reg, error;
 197
 198         error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
 199         if (error)
 200                 return error;
 201
 202         return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
 203 }
 204
 205 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
 206                                                 struct device_attribute *attr,
 207                                                 const char *buf, size_t count)
 208 {
 209         int reg, enable, error;
 210
 211         if (kstrtoint(buf, 0, &enable))
 212                 return -EINVAL;
 213
 214         error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
 215         if (error)
 216                 return error;
 217
 218         if (enable) {
 219                 reg |= BQ32K_TCFE;
 220                 error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 221                 if (error)
 222                         return error;
 223
 224                 dev_info(dev, "Enabled trickle charge FET bypass.\n");
 225         } else {
 226                 reg &= ~BQ32K_TCFE;
 227                 error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 228                 if (error)
 229                         return error;
 230
 231                 dev_info(dev, "Disabled trickle charge FET bypass.\n");
 232         }
 233
 234         return count;
 235 }
 236
 237 static DEVICE_ATTR(trickle_charge_bypass, 0644,
 238                    bq32k_sysfs_show_tricklecharge_bypass,
 239                    bq32k_sysfs_store_tricklecharge_bypass);
 240
 241 static int bq32k_sysfs_register(struct device *dev)
 242 {
 243         return device_create_file(dev, &dev_attr_trickle_charge_bypass);
 244 }
 245
 246 static void bq32k_sysfs_unregister(struct device *dev)
 247 {
 248         device_remove_file(dev, &dev_attr_trickle_charge_bypass);
 249 }
 250
 251 static int bq32k_probe(struct i2c_client *client,
 252                                 const struct i2c_device_id *id)
 253 {
 254         struct device *dev = &client->dev;
 255         struct rtc_device *rtc;
 256         uint8_t reg;
 257         int error;
 258
 259         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 260                 return -ENODEV;
 261
 262         /* Check Oscillator Stop flag */
 263         error = bq32k_read(dev, &reg, BQ32K_SECONDS, 1);
 264         if (!error && (reg & BQ32K_STOP)) {
 265                 dev_warn(dev, "Oscillator was halted. Restarting...\n");
 266                 reg &= ~BQ32K_STOP;
 267                 error = bq32k_write(dev, &reg, BQ32K_SECONDS, 1);
 268         }
 269         if (error)
 270                 return error;
 271
 272         /* Check Oscillator Failure flag */
 273         error = bq32k_read(dev, &reg, BQ32K_MINUTES, 1);
 274         if (error)
 275                 return error;
 276         if (reg & BQ32K_OF)
 277                 dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
 278
 279         if (client->dev.of_node)
 280                 trickle_charger_of_init(dev, client->dev.of_node);
 281
 282         rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
 283                                                 &bq32k_rtc_ops, THIS_MODULE);
 284         if (IS_ERR(rtc))
 285                 return PTR_ERR(rtc);
 286
 287         error = bq32k_sysfs_register(&client->dev);
 288         if (error) {
 289                 dev_err(&client->dev,
 290                         "Unable to create sysfs entries for rtc bq32000\n");
 291                 return error;
 292         }
 293
 294
 295         i2c_set_clientdata(client, rtc);
 296
 297         return 0;
 298 }
 299
 300 static int bq32k_remove(struct i2c_client *client)
 301 {
 302         bq32k_sysfs_unregister(&client->dev);
 303
 304         return 0;
 305 }
 306
 307 static const struct i2c_device_id bq32k_id[] = {
 308         { "bq32000", 0 },
 309         { }
 310 };
 311 MODULE_DEVICE_TABLE(i2c, bq32k_id);
 312
 313 static struct i2c_driver bq32k_driver = {
 314         .driver = {
 315                 .name   = "bq32k",
 316         },
 317         .probe          = bq32k_probe,
 318         .remove         = bq32k_remove,
 319         .id_table       = bq32k_id,
 320 };
 321
 322 module_i2c_driver(bq32k_driver);
 323
 324 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
 325 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
 326 MODULE_LICENSE("GPL");