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