drivers/rtc/rtc-s35390a.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Seiko Instruments S-35390A RTC Driver
0004  *
0005  * Copyright (c) 2007 Byron Bradley
0006  */
0007
0008 #include <linux/module.h>
0009 #include <linux/rtc.h>
0010 #include <linux/i2c.h>
0011 #include <linux/bitrev.h>
0012 #include <linux/bcd.h>
0013 #include <linux/slab.h>
0014 #include <linux/delay.h>
0015
0016 #define S35390A_CMD_STATUS1 0
0017 #define S35390A_CMD_STATUS2 1
0018 #define S35390A_CMD_TIME1   2
0019 #define S35390A_CMD_TIME2   3
0020 #define S35390A_CMD_INT2_REG1   5
0021
0022 #define S35390A_BYTE_YEAR   0
0023 #define S35390A_BYTE_MONTH  1
0024 #define S35390A_BYTE_DAY    2
0025 #define S35390A_BYTE_WDAY   3
0026 #define S35390A_BYTE_HOURS  4
0027 #define S35390A_BYTE_MINS   5
0028 #define S35390A_BYTE_SECS   6
0029
0030 #define S35390A_ALRM_BYTE_WDAY  0
0031 #define S35390A_ALRM_BYTE_HOURS 1
0032 #define S35390A_ALRM_BYTE_MINS  2
0033
0034 /* flags for STATUS1 */
0035 #define S35390A_FLAG_POC    BIT(0)
0036 #define S35390A_FLAG_BLD    BIT(1)
0037 #define S35390A_FLAG_INT2   BIT(2)
0038 #define S35390A_FLAG_24H    BIT(6)
0039 #define S35390A_FLAG_RESET  BIT(7)
0040
0041 /* flag for STATUS2 */
0042 #define S35390A_FLAG_TEST   BIT(0)
0043
0044 /* INT2 pin output mode */
0045 #define S35390A_INT2_MODE_MASK      0x0E
0046 #define S35390A_INT2_MODE_NOINTR    0x00
0047 #define S35390A_INT2_MODE_ALARM     BIT(1) /* INT2AE */
0048 #define S35390A_INT2_MODE_PMIN_EDG  BIT(2) /* INT2ME */
0049 #define S35390A_INT2_MODE_FREQ      BIT(3) /* INT2FE */
0050 #define S35390A_INT2_MODE_PMIN      (BIT(3) | BIT(2)) /* INT2FE | INT2ME */
0051
0052 static const struct i2c_device_id s35390a_id[] = {
0053     { "s35390a", 0 },
0054     { }
0055 };
0056 MODULE_DEVICE_TABLE(i2c, s35390a_id);
0057
0058 static const __maybe_unused struct of_device_id s35390a_of_match[] = {
0059     { .compatible = "s35390a" },
0060     { .compatible = "sii,s35390a" },
0061     { }
0062 };
0063 MODULE_DEVICE_TABLE(of, s35390a_of_match);
0064
0065 struct s35390a {
0066     struct i2c_client *client[8];
0067     struct rtc_device *rtc;
0068     int twentyfourhour;
0069 };
0070
0071 static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
0072 {
0073     struct i2c_client *client = s35390a->client[reg];
0074     struct i2c_msg msg[] = {
0075         {
0076             .addr = client->addr,
0077             .len = len,
0078             .buf = buf
0079         },
0080     };
0081
0082     if ((i2c_transfer(client->adapter, msg, 1)) != 1)
0083         return -EIO;
0084
0085     return 0;
0086 }
0087
0088 static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
0089 {
0090     struct i2c_client *client = s35390a->client[reg];
0091     struct i2c_msg msg[] = {
0092         {
0093             .addr = client->addr,
0094             .flags = I2C_M_RD,
0095             .len = len,
0096             .buf = buf
0097         },
0098     };
0099
0100     if ((i2c_transfer(client->adapter, msg, 1)) != 1)
0101         return -EIO;
0102
0103     return 0;
0104 }
0105
0106 static int s35390a_init(struct s35390a *s35390a)
0107 {
0108     u8 buf;
0109     int ret;
0110     unsigned initcount = 0;
0111
0112     /*
0113      * At least one of POC and BLD are set, so reinitialise chip. Keeping
0114      * this information in the hardware to know later that the time isn't
0115      * valid is unfortunately not possible because POC and BLD are cleared
0116      * on read. So the reset is best done now.
0117      *
0118      * The 24H bit is kept over reset, so set it already here.
0119      */
0120 initialize:
0121     buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
0122     ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
0123
0124     if (ret < 0)
0125         return ret;
0126
0127     ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
0128     if (ret < 0)
0129         return ret;
0130
0131     if (buf & (S35390A_FLAG_POC | S35390A_FLAG_BLD)) {
0132         /* Try up to five times to reset the chip */
0133         if (initcount < 5) {
0134             ++initcount;
0135             goto initialize;
0136         } else
0137             return -EIO;
0138     }
0139
0140     return 1;
0141 }
0142
0143 /*
0144  * Returns <0 on error, 0 if rtc is setup fine and 1 if the chip was reset.
0145  * To keep the information if an irq is pending, pass the value read from
0146  * STATUS1 to the caller.
0147  */
0148 static int s35390a_read_status(struct s35390a *s35390a, char *status1)
0149 {
0150     int ret;
0151
0152     ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, status1, 1);
0153     if (ret < 0)
0154         return ret;
0155
0156     if (*status1 & S35390A_FLAG_POC) {
0157         /*
0158          * Do not communicate for 0.5 seconds since the power-on
0159          * detection circuit is in operation.
0160          */
0161         msleep(500);
0162         return 1;
0163     } else if (*status1 & S35390A_FLAG_BLD)
0164         return 1;
0165     /*
0166      * If both POC and BLD are unset everything is fine.
0167      */
0168     return 0;
0169 }
0170
0171 static int s35390a_disable_test_mode(struct s35390a *s35390a)
0172 {
0173     char buf[1];
0174
0175     if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
0176         return -EIO;
0177
0178     if (!(buf[0] & S35390A_FLAG_TEST))
0179         return 0;
0180
0181     buf[0] &= ~S35390A_FLAG_TEST;
0182     return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
0183 }
0184
0185 static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
0186 {
0187     if (s35390a->twentyfourhour)
0188         return bin2bcd(hour);
0189
0190     if (hour < 12)
0191         return bin2bcd(hour);
0192
0193     return 0x40 | bin2bcd(hour - 12);
0194 }
0195
0196 static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
0197 {
0198     unsigned hour;
0199
0200     if (s35390a->twentyfourhour)
0201         return bcd2bin(reg & 0x3f);
0202
0203     hour = bcd2bin(reg & 0x3f);
0204     if (reg & 0x40)
0205         hour += 12;
0206
0207     return hour;
0208 }
0209
0210 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
0211 {
0212     struct i2c_client *client = to_i2c_client(dev);
0213     struct s35390a  *s35390a = i2c_get_clientdata(client);
0214     int i, err;
0215     char buf[7], status;
0216
0217     dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
0218         "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
0219         tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
0220         tm->tm_wday);
0221
0222     if (s35390a_read_status(s35390a, &status) == 1)
0223         s35390a_init(s35390a);
0224
0225     buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
0226     buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
0227     buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
0228     buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
0229     buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
0230     buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
0231     buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
0232
0233     /* This chip expects the bits of each byte to be in reverse order */
0234     for (i = 0; i < 7; ++i)
0235         buf[i] = bitrev8(buf[i]);
0236
0237     err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
0238
0239     return err;
0240 }
0241
0242 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
0243 {
0244     struct i2c_client *client = to_i2c_client(dev);
0245     struct s35390a *s35390a = i2c_get_clientdata(client);
0246     char buf[7], status;
0247     int i, err;
0248
0249     if (s35390a_read_status(s35390a, &status) == 1)
0250         return -EINVAL;
0251
0252     err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
0253     if (err < 0)
0254         return err;
0255
0256     /* This chip returns the bits of each byte in reverse order */
0257     for (i = 0; i < 7; ++i)
0258         buf[i] = bitrev8(buf[i]);
0259
0260     tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
0261     tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
0262     tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
0263     tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
0264     tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
0265     tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
0266     tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
0267
0268     dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
0269         "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
0270         tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
0271         tm->tm_wday);
0272
0273     return 0;
0274 }
0275
0276 static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
0277 {
0278     struct i2c_client *client = to_i2c_client(dev);
0279     struct s35390a *s35390a = i2c_get_clientdata(client);
0280     char buf[3], sts = 0;
0281     int err, i;
0282
0283     dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
0284         "mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
0285         alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
0286         alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
0287
0288     /* disable interrupt (which deasserts the irq line) */
0289     err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
0290     if (err < 0)
0291         return err;
0292
0293     /* clear pending interrupt (in STATUS1 only), if any */
0294     err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
0295     if (err < 0)
0296         return err;
0297
0298     if (alm->enabled)
0299         sts = S35390A_INT2_MODE_ALARM;
0300     else
0301         sts = S35390A_INT2_MODE_NOINTR;
0302
0303     /* set interupt mode*/
0304     err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
0305     if (err < 0)
0306         return err;
0307
0308     if (alm->time.tm_wday != -1)
0309         buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
0310     else
0311         buf[S35390A_ALRM_BYTE_WDAY] = 0;
0312
0313     buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
0314             alm->time.tm_hour) | 0x80;
0315     buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
0316
0317     if (alm->time.tm_hour >= 12)
0318         buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
0319
0320     for (i = 0; i < 3; ++i)
0321         buf[i] = bitrev8(buf[i]);
0322
0323     err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
0324                                 sizeof(buf));
0325
0326     return err;
0327 }
0328
0329 static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
0330 {
0331     struct i2c_client *client = to_i2c_client(dev);
0332     struct s35390a *s35390a = i2c_get_clientdata(client);
0333     char buf[3], sts;
0334     int i, err;
0335
0336     err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
0337     if (err < 0)
0338         return err;
0339
0340     if ((sts & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
0341         /*
0342          * When the alarm isn't enabled, the register to configure
0343          * the alarm time isn't accessible.
0344          */
0345         alm->enabled = 0;
0346         return 0;
0347     } else {
0348         alm->enabled = 1;
0349     }
0350
0351     err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
0352     if (err < 0)
0353         return err;
0354
0355     /* This chip returns the bits of each byte in reverse order */
0356     for (i = 0; i < 3; ++i)
0357         buf[i] = bitrev8(buf[i]);
0358
0359     /*
0360      * B0 of the three matching registers is an enable flag. Iff it is set
0361      * the configured value is used for matching.
0362      */
0363     if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
0364         alm->time.tm_wday =
0365             bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
0366
0367     if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
0368         alm->time.tm_hour =
0369             s35390a_reg2hr(s35390a,
0370                        buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
0371
0372     if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
0373         alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
0374
0375     /* alarm triggers always at s=0 */
0376     alm->time.tm_sec = 0;
0377
0378     dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
0379             __func__, alm->time.tm_min, alm->time.tm_hour,
0380             alm->time.tm_wday);
0381
0382     return 0;
0383 }
0384
0385 static int s35390a_rtc_ioctl(struct device *dev, unsigned int cmd,
0386                  unsigned long arg)
0387 {
0388     struct i2c_client *client = to_i2c_client(dev);
0389     struct s35390a *s35390a = i2c_get_clientdata(client);
0390     char sts;
0391     int err;
0392
0393     switch (cmd) {
0394     case RTC_VL_READ:
0395         /* s35390a_reset set lowvoltage flag and init RTC if needed */
0396         err = s35390a_read_status(s35390a, &sts);
0397         if (err < 0)
0398             return err;
0399         if (copy_to_user((void __user *)arg, &err, sizeof(int)))
0400             return -EFAULT;
0401         break;
0402     case RTC_VL_CLR:
0403         /* update flag and clear register */
0404         err = s35390a_init(s35390a);
0405         if (err < 0)
0406             return err;
0407         break;
0408     default:
0409         return -ENOIOCTLCMD;
0410     }
0411
0412     return 0;
0413 }
0414
0415 static const struct rtc_class_ops s35390a_rtc_ops = {
0416     .read_time  = s35390a_rtc_read_time,
0417     .set_time   = s35390a_rtc_set_time,
0418     .set_alarm  = s35390a_rtc_set_alarm,
0419     .read_alarm = s35390a_rtc_read_alarm,
0420     .ioctl          = s35390a_rtc_ioctl,
0421 };
0422
0423 static int s35390a_probe(struct i2c_client *client)
0424 {
0425     int err, err_read;
0426     unsigned int i;
0427     struct s35390a *s35390a;
0428     char buf, status1;
0429     struct device *dev = &client->dev;
0430
0431     if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
0432         return -ENODEV;
0433
0434     s35390a = devm_kzalloc(dev, sizeof(struct s35390a), GFP_KERNEL);
0435     if (!s35390a)
0436         return -ENOMEM;
0437
0438     s35390a->client[0] = client;
0439     i2c_set_clientdata(client, s35390a);
0440
0441     /* This chip uses multiple addresses, use dummy devices for them */
0442     for (i = 1; i < 8; ++i) {
0443         s35390a->client[i] = devm_i2c_new_dummy_device(dev,
0444                                    client->adapter,
0445                                    client->addr + i);
0446         if (IS_ERR(s35390a->client[i])) {
0447             dev_err(dev, "Address %02x unavailable\n",
0448                 client->addr + i);
0449             return PTR_ERR(s35390a->client[i]);
0450         }
0451     }
0452
0453     s35390a->rtc = devm_rtc_allocate_device(dev);
0454     if (IS_ERR(s35390a->rtc))
0455         return PTR_ERR(s35390a->rtc);
0456
0457     err_read = s35390a_read_status(s35390a, &status1);
0458     if (err_read < 0) {
0459         dev_err(dev, "error resetting chip\n");
0460         return err_read;
0461     }
0462
0463     if (status1 & S35390A_FLAG_24H)
0464         s35390a->twentyfourhour = 1;
0465     else
0466         s35390a->twentyfourhour = 0;
0467
0468     if (status1 & S35390A_FLAG_INT2) {
0469         /* disable alarm (and maybe test mode) */
0470         buf = 0;
0471         err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
0472         if (err < 0) {
0473             dev_err(dev, "error disabling alarm");
0474             return err;
0475         }
0476     } else {
0477         err = s35390a_disable_test_mode(s35390a);
0478         if (err < 0) {
0479             dev_err(dev, "error disabling test mode\n");
0480             return err;
0481         }
0482     }
0483
0484     device_set_wakeup_capable(dev, 1);
0485
0486     s35390a->rtc->ops = &s35390a_rtc_ops;
0487     s35390a->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
0488     s35390a->rtc->range_max = RTC_TIMESTAMP_END_2099;
0489
0490     set_bit(RTC_FEATURE_ALARM_RES_MINUTE, s35390a->rtc->features);
0491     clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, s35390a->rtc->features );
0492
0493     if (status1 & S35390A_FLAG_INT2)
0494         rtc_update_irq(s35390a->rtc, 1, RTC_AF);
0495
0496     return devm_rtc_register_device(s35390a->rtc);
0497 }
0498
0499 static struct i2c_driver s35390a_driver = {
0500     .driver     = {
0501         .name   = "rtc-s35390a",
0502         .of_match_table = of_match_ptr(s35390a_of_match),
0503     },
0504     .probe_new  = s35390a_probe,
0505     .id_table   = s35390a_id,
0506 };
0507
0508 module_i2c_driver(s35390a_driver);
0509
0510 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
0511 MODULE_DESCRIPTION("S35390A RTC driver");
0512 MODULE_LICENSE("GPL");