drivers/rtc/rtc-rs5c348.c

   1 /*
   2  * A SPI driver for the Ricoh RS5C348 RTC
   3  *
   4  * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * The board specific init code should provide characteristics of this
  11  * device:
  12  *     Mode 1 (High-Active, Shift-Then-Sample), High Avtive CS
  13  */
  14
  15 #include <linux/bcd.h>
  16 #include <linux/delay.h>
  17 #include <linux/device.h>
  18 #include <linux/errno.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/string.h>
  22 #include <linux/rtc.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/spi/spi.h>
  25
  26 #define DRV_VERSION "0.2"
  27
  28 #define RS5C348_REG_SECS        0
  29 #define RS5C348_REG_MINS        1
  30 #define RS5C348_REG_HOURS       2
  31 #define RS5C348_REG_WDAY        3
  32 #define RS5C348_REG_DAY 4
  33 #define RS5C348_REG_MONTH       5
  34 #define RS5C348_REG_YEAR        6
  35 #define RS5C348_REG_CTL1        14
  36 #define RS5C348_REG_CTL2        15
  37
  38 #define RS5C348_SECS_MASK       0x7f
  39 #define RS5C348_MINS_MASK       0x7f
  40 #define RS5C348_HOURS_MASK      0x3f
  41 #define RS5C348_WDAY_MASK       0x03
  42 #define RS5C348_DAY_MASK        0x3f
  43 #define RS5C348_MONTH_MASK      0x1f
  44
  45 #define RS5C348_BIT_PM  0x20    /* REG_HOURS */
  46 #define RS5C348_BIT_Y2K 0x80    /* REG_MONTH */
  47 #define RS5C348_BIT_24H 0x20    /* REG_CTL1 */
  48 #define RS5C348_BIT_XSTP        0x10    /* REG_CTL2 */
  49 #define RS5C348_BIT_VDET        0x40    /* REG_CTL2 */
  50
  51 #define RS5C348_CMD_W(addr)     (((addr) << 4) | 0x08)  /* single write */
  52 #define RS5C348_CMD_R(addr)     (((addr) << 4) | 0x0c)  /* single read */
  53 #define RS5C348_CMD_MW(addr)    (((addr) << 4) | 0x00)  /* burst write */
  54 #define RS5C348_CMD_MR(addr)    (((addr) << 4) | 0x04)  /* burst read */
  55
  56 struct rs5c348_plat_data {
  57         struct rtc_device *rtc;
  58         int rtc_24h;
  59 };
  60
  61 static int
  62 rs5c348_rtc_set_time(struct device *dev, struct rtc_time *tm)
  63 {
  64         struct spi_device *spi = to_spi_device(dev);
  65         struct rs5c348_plat_data *pdata = spi->dev.platform_data;
  66         u8 txbuf[5+7], *txp;
  67         int ret;
  68
  69         /* Transfer 5 bytes before writing SEC.  This gives 31us for carry. */
  70         txp = txbuf;
  71         txbuf[0] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
  72         txbuf[1] = 0;   /* dummy */
  73         txbuf[2] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
  74         txbuf[3] = 0;   /* dummy */
  75         txbuf[4] = RS5C348_CMD_MW(RS5C348_REG_SECS); /* cmd, sec, ... */
  76         txp = &txbuf[5];
  77         txp[RS5C348_REG_SECS] = bin2bcd(tm->tm_sec);
  78         txp[RS5C348_REG_MINS] = bin2bcd(tm->tm_min);
  79         if (pdata->rtc_24h) {
  80                 txp[RS5C348_REG_HOURS] = bin2bcd(tm->tm_hour);
  81         } else {
  82                 /* hour 0 is AM12, noon is PM12 */
  83                 txp[RS5C348_REG_HOURS] = bin2bcd((tm->tm_hour + 11) % 12 + 1) |
  84                         (tm->tm_hour >= 12 ? RS5C348_BIT_PM : 0);
  85         }
  86         txp[RS5C348_REG_WDAY] = bin2bcd(tm->tm_wday);
  87         txp[RS5C348_REG_DAY] = bin2bcd(tm->tm_mday);
  88         txp[RS5C348_REG_MONTH] = bin2bcd(tm->tm_mon + 1) |
  89                 (tm->tm_year >= 100 ? RS5C348_BIT_Y2K : 0);
  90         txp[RS5C348_REG_YEAR] = bin2bcd(tm->tm_year % 100);
  91         /* write in one transfer to avoid data inconsistency */
  92         ret = spi_write_then_read(spi, txbuf, sizeof(txbuf), NULL, 0);
  93         udelay(62);     /* Tcsr 62us */
  94         return ret;
  95 }
  96
  97 static int
  98 rs5c348_rtc_read_time(struct device *dev, struct rtc_time *tm)
  99 {
 100         struct spi_device *spi = to_spi_device(dev);
 101         struct rs5c348_plat_data *pdata = spi->dev.platform_data;
 102         u8 txbuf[5], rxbuf[7];
 103         int ret;
 104
 105         /* Transfer 5 byte befores reading SEC.  This gives 31us for carry. */
 106         txbuf[0] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
 107         txbuf[1] = 0;   /* dummy */
 108         txbuf[2] = RS5C348_CMD_R(RS5C348_REG_CTL2); /* cmd, ctl2 */
 109         txbuf[3] = 0;   /* dummy */
 110         txbuf[4] = RS5C348_CMD_MR(RS5C348_REG_SECS); /* cmd, sec, ... */
 111
 112         /* read in one transfer to avoid data inconsistency */
 113         ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
 114                                   rxbuf, sizeof(rxbuf));
 115         udelay(62);     /* Tcsr 62us */
 116         if (ret < 0)
 117                 return ret;
 118
 119         tm->tm_sec = bcd2bin(rxbuf[RS5C348_REG_SECS] & RS5C348_SECS_MASK);
 120         tm->tm_min = bcd2bin(rxbuf[RS5C348_REG_MINS] & RS5C348_MINS_MASK);
 121         tm->tm_hour = bcd2bin(rxbuf[RS5C348_REG_HOURS] & RS5C348_HOURS_MASK);
 122         if (!pdata->rtc_24h) {
 123                 tm->tm_hour %= 12;
 124                 if (rxbuf[RS5C348_REG_HOURS] & RS5C348_BIT_PM)
 125                         tm->tm_hour += 12;
 126         }
 127         tm->tm_wday = bcd2bin(rxbuf[RS5C348_REG_WDAY] & RS5C348_WDAY_MASK);
 128         tm->tm_mday = bcd2bin(rxbuf[RS5C348_REG_DAY] & RS5C348_DAY_MASK);
 129         tm->tm_mon =
 130                 bcd2bin(rxbuf[RS5C348_REG_MONTH] & RS5C348_MONTH_MASK) - 1;
 131         /* year is 1900 + tm->tm_year */
 132         tm->tm_year = bcd2bin(rxbuf[RS5C348_REG_YEAR]) +
 133                 ((rxbuf[RS5C348_REG_MONTH] & RS5C348_BIT_Y2K) ? 100 : 0);
 134
 135         if (rtc_valid_tm(tm) < 0) {
 136                 dev_err(&spi->dev, "retrieved date/time is not valid.\n");
 137                 rtc_time_to_tm(0, tm);
 138         }
 139
 140         return 0;
 141 }
 142
 143 static const struct rtc_class_ops rs5c348_rtc_ops = {
 144         .read_time      = rs5c348_rtc_read_time,
 145         .set_time       = rs5c348_rtc_set_time,
 146 };
 147
 148 static struct spi_driver rs5c348_driver;
 149
 150 static int __devinit rs5c348_probe(struct spi_device *spi)
 151 {
 152         int ret;
 153         struct rtc_device *rtc;
 154         struct rs5c348_plat_data *pdata;
 155
 156         pdata = kzalloc(sizeof(struct rs5c348_plat_data), GFP_KERNEL);
 157         if (!pdata)
 158                 return -ENOMEM;
 159         spi->dev.platform_data = pdata;
 160
 161         /* Check D7 of SECOND register */
 162         ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_SECS));
 163         if (ret < 0 || (ret & 0x80)) {
 164                 dev_err(&spi->dev, "not found.\n");
 165                 goto kfree_exit;
 166         }
 167
 168         dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
 169         dev_info(&spi->dev, "spiclk %u KHz.\n",
 170                  (spi->max_speed_hz + 500) / 1000);
 171
 172         /* turn RTC on if it was not on */
 173         ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL2));
 174         if (ret < 0)
 175                 goto kfree_exit;
 176         if (ret & (RS5C348_BIT_XSTP | RS5C348_BIT_VDET)) {
 177                 u8 buf[2];
 178                 struct rtc_time tm;
 179                 if (ret & RS5C348_BIT_VDET)
 180                         dev_warn(&spi->dev, "voltage-low detected.\n");
 181                 if (ret & RS5C348_BIT_XSTP)
 182                         dev_warn(&spi->dev, "oscillator-stop detected.\n");
 183                 rtc_time_to_tm(0, &tm); /* 1970/1/1 */
 184                 ret = rs5c348_rtc_set_time(&spi->dev, &tm);
 185                 if (ret < 0)
 186                         goto kfree_exit;
 187                 buf[0] = RS5C348_CMD_W(RS5C348_REG_CTL2);
 188                 buf[1] = 0;
 189                 ret = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
 190                 if (ret < 0)
 191                         goto kfree_exit;
 192         }
 193
 194         ret = spi_w8r8(spi, RS5C348_CMD_R(RS5C348_REG_CTL1));
 195         if (ret < 0)
 196                 goto kfree_exit;
 197         if (ret & RS5C348_BIT_24H)
 198                 pdata->rtc_24h = 1;
 199
 200         rtc = rtc_device_register(rs5c348_driver.driver.name, &spi->dev,
 201                                   &rs5c348_rtc_ops, THIS_MODULE);
 202
 203         if (IS_ERR(rtc)) {
 204                 ret = PTR_ERR(rtc);
 205                 goto kfree_exit;
 206         }
 207
 208         pdata->rtc = rtc;
 209
 210         return 0;
 211  kfree_exit:
 212         kfree(pdata);
 213         return ret;
 214 }
 215
 216 static int __devexit rs5c348_remove(struct spi_device *spi)
 217 {
 218         struct rs5c348_plat_data *pdata = spi->dev.platform_data;
 219         struct rtc_device *rtc = pdata->rtc;
 220
 221         if (rtc)
 222                 rtc_device_unregister(rtc);
 223         kfree(pdata);
 224         return 0;
 225 }
 226
 227 static struct spi_driver rs5c348_driver = {
 228         .driver = {
 229                 .name   = "rtc-rs5c348",
 230                 .bus    = &spi_bus_type,
 231                 .owner  = THIS_MODULE,
 232         },
 233         .probe  = rs5c348_probe,
 234         .remove = __devexit_p(rs5c348_remove),
 235 };
 236
 237 static __init int rs5c348_init(void)
 238 {
 239         return spi_register_driver(&rs5c348_driver);
 240 }
 241
 242 static __exit void rs5c348_exit(void)
 243 {
 244         spi_unregister_driver(&rs5c348_driver);
 245 }
 246
 247 module_init(rs5c348_init);
 248 module_exit(rs5c348_exit);
 249
 250 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 251 MODULE_DESCRIPTION("Ricoh RS5C348 RTC driver");
 252 MODULE_LICENSE("GPL");
 253 MODULE_VERSION(DRV_VERSION);