drivers/rtc/rtc-bq32k.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Driver for TI BQ32000 RTC.
   4  *
   5  * Copyright (C) 2009 Semihalf.
   6  * Copyright (C) 2014 Pavel Machek <pavel@denx.de>
   7  *
   8  * You can get hardware description at
   9  * https://www.ti.com/lit/ds/symlink/bq32000.pdf
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/i2c.h>
  14 #include <linux/rtc.h>
  15 #include <linux/init.h>
  16 #include <linux/kstrtox.h>
  17 #include <linux/errno.h>
  18 #include <linux/bcd.h>
  19
  20 #define BQ32K_SECONDS           0x00    /* Seconds register address */
  21 #define BQ32K_SECONDS_MASK      0x7F    /* Mask over seconds value */
  22 #define BQ32K_STOP              0x80    /* Oscillator Stop flat */
  23
  24 #define BQ32K_MINUTES           0x01    /* Minutes register address */
  25 #define BQ32K_MINUTES_MASK      0x7F    /* Mask over minutes value */
  26 #define BQ32K_OF                0x80    /* Oscillator Failure flag */
  27
  28 #define BQ32K_HOURS_MASK        0x3F    /* Mask over hours value */
  29 #define BQ32K_CENT              0x40    /* Century flag */
  30 #define BQ32K_CENT_EN           0x80    /* Century flag enable bit */
  31
  32 #define BQ32K_CALIBRATION       0x07    /* CAL_CFG1, calibration and control */
  33 #define BQ32K_TCH2              0x08    /* Trickle charge enable */
  34 #define BQ32K_CFG2              0x09    /* Trickle charger control */
  35 #define BQ32K_TCFE              BIT(6)  /* Trickle charge FET bypass */
  36
  37 #define MAX_LEN                 10      /* Maximum number of consecutive
  38                                          * register for this particular RTC.
  39                                          */
  40
  41 struct bq32k_regs {
  42         uint8_t         seconds;
  43         uint8_t         minutes;
  44         uint8_t         cent_hours;
  45         uint8_t         day;
  46         uint8_t         date;
  47         uint8_t         month;
  48         uint8_t         years;
  49 };
  50
  51 static struct i2c_driver bq32k_driver;
  52
  53 static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
  54 {
  55         struct i2c_client *client = to_i2c_client(dev);
  56         struct i2c_msg msgs[] = {
  57                 {
  58                         .addr = client->addr,
  59                         .flags = 0,
  60                         .len = 1,
  61                         .buf = &off,
  62                 }, {
  63                         .addr = client->addr,
  64                         .flags = I2C_M_RD,
  65                         .len = len,
  66                         .buf = data,
  67                 }
  68         };
  69
  70         if (i2c_transfer(client->adapter, msgs, 2) == 2)
  71                 return 0;
  72
  73         return -EIO;
  74 }
  75
  76 static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
  77 {
  78         struct i2c_client *client = to_i2c_client(dev);
  79         uint8_t buffer[MAX_LEN + 1];
  80
  81         buffer[0] = off;
  82         memcpy(&buffer[1], data, len);
  83
  84         if (i2c_master_send(client, buffer, len + 1) == len + 1)
  85                 return 0;
  86
  87         return -EIO;
  88 }
  89
  90 static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
  91 {
  92         struct bq32k_regs regs;
  93         int error;
  94
  95         error = bq32k_read(dev, &regs, 0, sizeof(regs));
  96         if (error)
  97                 return error;
  98
  99         /*
 100          * In case of oscillator failure, the register contents should be
 101          * considered invalid. The flag is cleared the next time the RTC is set.
 102          */
 103         if (regs.minutes & BQ32K_OF)
 104                 return -EINVAL;
 105
 106         tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
 107         tm->tm_min = bcd2bin(regs.minutes & BQ32K_MINUTES_MASK);
 108         tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
 109         tm->tm_mday = bcd2bin(regs.date);
 110         tm->tm_wday = bcd2bin(regs.day) - 1;
 111         tm->tm_mon = bcd2bin(regs.month) - 1;
 112         tm->tm_year = bcd2bin(regs.years) +
 113                                 ((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
 114
 115         return 0;
 116 }
 117
 118 static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
 119 {
 120         struct bq32k_regs regs;
 121
 122         regs.seconds = bin2bcd(tm->tm_sec);
 123         regs.minutes = bin2bcd(tm->tm_min);
 124         regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
 125         regs.day = bin2bcd(tm->tm_wday + 1);
 126         regs.date = bin2bcd(tm->tm_mday);
 127         regs.month = bin2bcd(tm->tm_mon + 1);
 128
 129         if (tm->tm_year >= 100) {
 130                 regs.cent_hours |= BQ32K_CENT;
 131                 regs.years = bin2bcd(tm->tm_year - 100);
 132         } else
 133                 regs.years = bin2bcd(tm->tm_year);
 134
 135         return bq32k_write(dev, &regs, 0, sizeof(regs));
 136 }
 137
 138 static const struct rtc_class_ops bq32k_rtc_ops = {
 139         .read_time      = bq32k_rtc_read_time,
 140         .set_time       = bq32k_rtc_set_time,
 141 };
 142
 143 static int trickle_charger_of_init(struct device *dev, struct device_node *node)
 144 {
 145         unsigned char reg;
 146         int error;
 147         u32 ohms = 0;
 148
 149         if (of_property_read_u32(node, "trickle-resistor-ohms" , &ohms))
 150                 return 0;
 151
 152         switch (ohms) {
 153         case 180+940:
 154                 /*
 155                  * TCHE[3:0] == 0x05, TCH2 == 1, TCFE == 0 (charging
 156                  * over diode and 940ohm resistor)
 157                  */
 158
 159                 if (of_property_read_bool(node, "trickle-diode-disable")) {
 160                         dev_err(dev, "diode and resistor mismatch\n");
 161                         return -EINVAL;
 162                 }
 163                 reg = 0x05;
 164                 break;
 165
 166         case 180+20000:
 167                 /* diode disabled */
 168
 169                 if (!of_property_read_bool(node, "trickle-diode-disable")) {
 170                         dev_err(dev, "bq32k: diode and resistor mismatch\n");
 171                         return -EINVAL;
 172                 }
 173                 reg = 0x45;
 174                 break;
 175
 176         default:
 177                 dev_err(dev, "invalid resistor value (%d)\n", ohms);
 178                 return -EINVAL;
 179         }
 180
 181         error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 182         if (error)
 183                 return error;
 184
 185         reg = 0x20;
 186         error = bq32k_write(dev, &reg, BQ32K_TCH2, 1);
 187         if (error)
 188                 return error;
 189
 190         dev_info(dev, "Enabled trickle RTC battery charge.\n");
 191         return 0;
 192 }
 193
 194 static ssize_t bq32k_sysfs_show_tricklecharge_bypass(struct device *dev,
 195                                                struct device_attribute *attr,
 196                                                char *buf)
 197 {
 198         int reg, error;
 199
 200         error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
 201         if (error)
 202                 return error;
 203
 204         return sprintf(buf, "%d\n", (reg & BQ32K_TCFE) ? 1 : 0);
 205 }
 206
 207 static ssize_t bq32k_sysfs_store_tricklecharge_bypass(struct device *dev,
 208                                                 struct device_attribute *attr,
 209                                                 const char *buf, size_t count)
 210 {
 211         int reg, enable, error;
 212
 213         if (kstrtoint(buf, 0, &enable))
 214                 return -EINVAL;
 215
 216         error = bq32k_read(dev, &reg, BQ32K_CFG2, 1);
 217         if (error)
 218                 return error;
 219
 220         if (enable) {
 221                 reg |= BQ32K_TCFE;
 222                 error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 223                 if (error)
 224                         return error;
 225
 226                 dev_info(dev, "Enabled trickle charge FET bypass.\n");
 227         } else {
 228                 reg &= ~BQ32K_TCFE;
 229                 error = bq32k_write(dev, &reg, BQ32K_CFG2, 1);
 230                 if (error)
 231                         return error;
 232
 233                 dev_info(dev, "Disabled trickle charge FET bypass.\n");
 234         }
 235
 236         return count;
 237 }
 238
 239 static DEVICE_ATTR(trickle_charge_bypass, 0644,
 240                    bq32k_sysfs_show_tricklecharge_bypass,
 241                    bq32k_sysfs_store_tricklecharge_bypass);
 242
 243 static int bq32k_sysfs_register(struct device *dev)
 244 {
 245         return device_create_file(dev, &dev_attr_trickle_charge_bypass);
 246 }
 247
 248 static void bq32k_sysfs_unregister(struct device *dev)
 249 {
 250         device_remove_file(dev, &dev_attr_trickle_charge_bypass);
 251 }
 252
 253 static int bq32k_probe(struct i2c_client *client)
 254 {
 255         struct device *dev = &client->dev;
 256         struct rtc_device *rtc;
 257         uint8_t reg;
 258         int error;
 259
 260         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 261                 return -ENODEV;
 262
 263         /* Check Oscillator Stop flag */
 264         error = bq32k_read(dev, &reg, BQ32K_SECONDS, 1);
 265         if (!error && (reg & BQ32K_STOP)) {
 266                 dev_warn(dev, "Oscillator was halted. Restarting...\n");
 267                 reg &= ~BQ32K_STOP;
 268                 error = bq32k_write(dev, &reg, BQ32K_SECONDS, 1);
 269         }
 270         if (error)
 271                 return error;
 272
 273         /* Check Oscillator Failure flag */
 274         error = bq32k_read(dev, &reg, BQ32K_MINUTES, 1);
 275         if (error)
 276                 return error;
 277         if (reg & BQ32K_OF)
 278                 dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
 279
 280         if (client->dev.of_node)
 281                 trickle_charger_of_init(dev, client->dev.of_node);
 282
 283         rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
 284                                                 &bq32k_rtc_ops, THIS_MODULE);
 285         if (IS_ERR(rtc))
 286                 return PTR_ERR(rtc);
 287
 288         error = bq32k_sysfs_register(&client->dev);
 289         if (error) {
 290                 dev_err(&client->dev,
 291                         "Unable to create sysfs entries for rtc bq32000\n");
 292                 return error;
 293         }
 294
 295
 296         i2c_set_clientdata(client, rtc);
 297
 298         return 0;
 299 }
 300
 301 static void bq32k_remove(struct i2c_client *client)
 302 {
 303         bq32k_sysfs_unregister(&client->dev);
 304 }
 305
 306 static const struct i2c_device_id bq32k_id[] = {
 307         { "bq32000" },
 308         { }
 309 };
 310 MODULE_DEVICE_TABLE(i2c, bq32k_id);
 311
 312 static const __maybe_unused struct of_device_id bq32k_of_match[] = {
 313         { .compatible = "ti,bq32000" },
 314         { }
 315 };
 316 MODULE_DEVICE_TABLE(of, bq32k_of_match);
 317
 318 static struct i2c_driver bq32k_driver = {
 319         .driver = {
 320                 .name   = "bq32k",
 321                 .of_match_table = of_match_ptr(bq32k_of_match),
 322         },
 323         .probe          = bq32k_probe,
 324         .remove         = bq32k_remove,
 325         .id_table       = bq32k_id,
 326 };
 327
 328 module_i2c_driver(bq32k_driver);
 329
 330 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
 331 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
 332 MODULE_LICENSE("GPL");