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 #define MAX_LEN                 10      /* Maximum number of consecutive
  40                                          * register for this particular RTC.
  41                                          */
  42
  43 struct bq32k_regs {
  44         uint8_t         seconds;
  45         uint8_t         minutes;
  46         uint8_t         cent_hours;
  47         uint8_t         day;
  48         uint8_t         date;
  49         uint8_t         month;
  50         uint8_t         years;
  51 };
  52
  53 static struct i2c_driver bq32k_driver;
  54
  55 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
  56 {
  57         struct i2c_client *client = to_i2c_client(dev);
  58         struct i2c_msg msgs[] = {
  59                 {
  60                         .addr = client->addr,
  61                         .flags = 0,
  62                         .len = 1,
  63                         .buf = &off,
  64                 }, {
  65                         .addr = client->addr,
  66                         .flags = I2C_M_RD,
  67                         .len = len,
  68                         .buf = data,
  69                 }
  70         };
  71
  72         if (i2c_transfer(client->adapter, msgs, 2) == 2)
  73                 return 0;
  74
  75         return -EIO;
  76 }
  77
  78 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
  79 {
  80         struct i2c_client *client = to_i2c_client(dev);
  81         uint8_t buffer[MAX_LEN + 1];
  82
  83         buffer[0] = off;
  84         memcpy(&buffer[1], data, len);
  85
  86         if (i2c_master_send(client, buffer, len + 1) == len + 1)
  87                 return 0;
  88
  89         return -EIO;
  90 }
  91
  92 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
  93 {
  94         struct bq32k_regs regs;
  95         int error;
  96
  97         error = bq32k_read(dev, &regs, 0, sizeof(regs));
  98         if (error)
  99                 return error;
 100
 101         /*
 102          * In case of oscillator failure, the register contents should be
 103          * considered invalid. The flag is cleared the next time the RTC is set.
 104          */
 105         if (regs.minutes & BQ32K_OF)
 106                 return -EINVAL;
 107
 108         tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
 109         tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
 110         tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
 111         tm->tm_mday = bcd2bin(regs.date);
 112         tm->tm_wday = bcd2bin(regs.day) - 1;
 113         tm->tm_mon = bcd2bin(regs.month) - 1;
 114         tm->tm_year = bcd2bin(regs.years) +
 115                                 ((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
 116
 117         return 0;
 118 }
 119
 120 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
 121 {
 122         struct bq32k_regs regs;
 123
 124         regs.seconds = bin2bcd(tm->tm_sec);
 125         regs.minutes = bin2bcd(tm->tm_min);
 126         regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
 127         regs.day = bin2bcd(tm->tm_wday + 1);
 128         regs.date = bin2bcd(tm->tm_mday);
 129         regs.month = bin2bcd(tm->tm_mon + 1);
 130
 131         if (tm->tm_year >= 100) {
 132                 regs.cent_hours |= BQ32K_CENT;
 133                 regs.years = bin2bcd(tm->tm_year - 100);
 134         } else
 135                 regs.years = bin2bcd(tm->tm_year);
 136
 137         return bq32k_write(dev, &regs, 0, sizeof(regs));
 138 }
 139
 140 static const struct rtc_class_ops bq32k_rtc_ops = {
 141         .read_time      = bq32k_rtc_read_time,
 142         .set_time       = bq32k_rtc_set_time,
 143 };
 144
 145 static int trickle_charger_of_init(struct device *dev, struct device_node *node)
 146 {
 147         unsigned char reg;
 148         int error;
 149         u32 ohms = 0;
 150
 151         if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
 152                 return 0;
 153
 154         switch (ohms) {
 155         case 180+940:
 156                 /*
 157                  * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
 158                  * over diode and 940ohm resistor)
 159                  */
 160
 161                 if (of_property_read_bool(node, "trickle-diode-disable")) {
 162                         dev_err(dev, "diode and resistor mismatch\n");
 163                         return -EINVAL;
 164                 }
 165                 reg = 0x05;
 166                 break;
 167
 168         case 180+20000:
 169                 /* diode disabled */
 170
 171                 if (!of_property_read_bool(node, "trickle-diode-disable")) {
 172                         dev_err(dev, "bq32k: diode and resistor mismatch\n");
 173                         return -EINVAL;
 174                 }
 175                 reg = 0x45;
 176                 break;
 177
 178         default:
 179                 dev_err(dev, "invalid resistor value (%d)\n", ohms);
 180                 return -EINVAL;
 181         }
 182
 183         error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 184         if (error)
 185                 return error;
 186
 187         reg = 0x20;
 188         error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);
 189         if (error)
 190                 return error;
 191
 192         dev_info(dev, "Enabled trickle RTC battery charge.\n");
 193         return 0;
 194 }
 195
 196 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
 197                                                struct device_attribute *attr,
 198                                                char *buf)
 199 {
 200         int reg, error;
 201
 202         error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
 203         if (error)
 204                 return error;
 205
 206         return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
 207 }
 208
 209 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
 210                                                 struct device_attribute *attr,
 211                                                 const char *buf, size_t count)
 212 {
 213         int reg, enable, error;
 214
 215         if (kstrtoint(buf, 0, &enable))
 216                 return -EINVAL;
 217
 218         error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
 219         if (error)
 220                 return error;
 221
 222         if (enable) {
 223                 reg |= BQ32K_TCFE;
 224                 error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 225                 if (error)
 226                         return error;
 227
 228                 dev_info(dev, "Enabled trickle charge FET bypass.\n");
 229         } else {
 230                 reg &= ~BQ32K_TCFE;
 231                 error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 232                 if (error)
 233                         return error;
 234
 235                 dev_info(dev, "Disabled trickle charge FET bypass.\n");
 236         }
 237
 238         return count;
 239 }
 240
 241 static DEVICE_ATTR(trickle_charge_bypass, 0644,
 242                    bq32k_sysfs_show_tricklecharge_bypass,
 243                    bq32k_sysfs_store_tricklecharge_bypass);
 244
 245 static int bq32k_sysfs_register(struct device *dev)
 246 {
 247         return device_create_file(dev, &dev_attr_trickle_charge_bypass);
 248 }
 249
 250 static void bq32k_sysfs_unregister(struct device *dev)
 251 {
 252         device_remove_file(dev, &dev_attr_trickle_charge_bypass);
 253 }
 254
 255 static int bq32k_probe(struct i2c_client *client,
 256                                 const struct i2c_device_id *id)
 257 {
 258         struct device *dev = &client->dev;
 259         struct rtc_device *rtc;
 260         uint8_t reg;
 261         int error;
 262
 263         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 264                 return -ENODEV;
 265
 266         /* Check Oscillator Stop flag */
 267         error = bq32k_read(dev, &reg, BQ32K_SECONDS, 1);
 268         if (!error && (reg & BQ32K_STOP)) {
 269                 dev_warn(dev, "Oscillator was halted. Restarting...\n");
 270                 reg &= ~BQ32K_STOP;
 271                 error = bq32k_write(dev, &reg, BQ32K_SECONDS, 1);
 272         }
 273         if (error)
 274                 return error;
 275
 276         /* Check Oscillator Failure flag */
 277         error = bq32k_read(dev, &reg, BQ32K_MINUTES, 1);
 278         if (error)
 279                 return error;
 280         if (reg & BQ32K_OF)
 281                 dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
 282
 283         if (client->dev.of_node)
 284                 trickle_charger_of_init(dev, client->dev.of_node);
 285
 286         rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
 287                                                 &bq32k_rtc_ops, THIS_MODULE);
 288         if (IS_ERR(rtc))
 289                 return PTR_ERR(rtc);
 290
 291         error = bq32k_sysfs_register(&client->dev);
 292         if (error) {
 293                 dev_err(&client->dev,
 294                         "Unable to create sysfs entries for rtc bq32000\n");
 295                 return error;
 296         }
 297
 298
 299         i2c_set_clientdata(client, rtc);
 300
 301         return 0;
 302 }
 303
 304 static int bq32k_remove(struct i2c_client *client)
 305 {
 306         bq32k_sysfs_unregister(&client->dev);
 307
 308         return 0;
 309 }
 310
 311 static const struct i2c_device_id bq32k_id[] = {
 312         { "bq32000", 0 },
 313         { }
 314 };
 315 MODULE_DEVICE_TABLE(i2c, bq32k_id);
 316
 317 static const struct of_device_id bq32k_of_match[] = {
 318         { .compatible = "ti,bq32000" },
 319         { }
 320 };
 321 MODULE_DEVICE_TABLE(of, bq32k_of_match);
 322
 323 static struct i2c_driver bq32k_driver = {
 324         .driver = {
 325                 .name   = "bq32k",
 326                 .of_match_table = of_match_ptr(bq32k_of_match),
 327         },
 328         .probe          = bq32k_probe,
 329         .remove         = bq32k_remove,
 330         .id_table       = bq32k_id,
 331 };
 332
 333 module_i2c_driver(bq32k_driver);
 334
 335 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
 336 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
 337 MODULE_LICENSE("GPL");