drivers/rtc/rtc-pcf2123.c

   1 /*
   2  * An SPI driver for the Philips PCF2123 RTC
   3  * Copyright 2009 Cyber Switching, Inc.
   4  *
   5  * Author: Chris Verges <chrisv@cyberswitching.com>
   6  * Maintainers: http://www.cyberswitching.com
   7  *
   8  * based on the RS5C348 driver in this same directory.
   9  *
  10  * Thanks to Christian Pellegrin <chripell@fsfe.org> for
  11  * the sysfs contributions to this driver.
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License version 2 as
  15  * published by the Free Software Foundation.
  16  *
  17  * Please note that the CS is active high, so platform data
  18  * should look something like:
  19  *
  20  * static struct spi_board_info ek_spi_devices[] = {
  21  *      ...
  22  *      {
  23  *              .modalias               = "rtc-pcf2123",
  24  *              .chip_select            = 1,
  25  *              .controller_data        = (void *)AT91_PIN_PA10,
  26  *              .max_speed_hz           = 1000 * 1000,
  27  *              .mode                   = SPI_CS_HIGH,
  28  *              .bus_num                = 0,
  29  *      },
  30  *      ...
  31  *};
  32  *
  33  */
  34
  35 #include <linux/bcd.h>
  36 #include <linux/delay.h>
  37 #include <linux/device.h>
  38 #include <linux/errno.h>
  39 #include <linux/init.h>
  40 #include <linux/kernel.h>
  41 #include <linux/string.h>
  42 #include <linux/slab.h>
  43 #include <linux/rtc.h>
  44 #include <linux/spi/spi.h>
  45 #include <linux/module.h>
  46
  47 #define DRV_VERSION "0.6"
  48
  49 #define PCF2123_REG_CTRL1       (0x00)  /* Control Register 1 */
  50 #define PCF2123_REG_CTRL2       (0x01)  /* Control Register 2 */
  51 #define PCF2123_REG_SC          (0x02)  /* datetime */
  52 #define PCF2123_REG_MN          (0x03)
  53 #define PCF2123_REG_HR          (0x04)
  54 #define PCF2123_REG_DM          (0x05)
  55 #define PCF2123_REG_DW          (0x06)
  56 #define PCF2123_REG_MO          (0x07)
  57 #define PCF2123_REG_YR          (0x08)
  58
  59 #define PCF2123_SUBADDR         (1 << 4)
  60 #define PCF2123_WRITE           ((0 << 7) | PCF2123_SUBADDR)
  61 #define PCF2123_READ            ((1 << 7) | PCF2123_SUBADDR)
  62
  63 static struct spi_driver pcf2123_driver;
  64
  65 struct pcf2123_sysfs_reg {
  66         struct device_attribute attr;
  67         char name[2];
  68 };
  69
  70 struct pcf2123_plat_data {
  71         struct rtc_device *rtc;
  72         struct pcf2123_sysfs_reg regs[16];
  73 };
  74
  75 /*
  76  * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
  77  * is released properly after an SPI write.  This function should be
  78  * called after EVERY read/write call over SPI.
  79  */
  80 static inline void pcf2123_delay_trec(void)
  81 {
  82         ndelay(30);
  83 }
  84
  85 static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
  86                             char *buffer)
  87 {
  88         struct spi_device *spi = to_spi_device(dev);
  89         struct pcf2123_sysfs_reg *r;
  90         u8 txbuf[1], rxbuf[1];
  91         unsigned long reg;
  92         int ret;
  93
  94         r = container_of(attr, struct pcf2123_sysfs_reg, attr);
  95
  96         if (strict_strtoul(r->name, 16, &reg))
  97                 return -EINVAL;
  98
  99         txbuf[0] = PCF2123_READ | reg;
 100         ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
 101         if (ret < 0)
 102                 return -EIO;
 103         pcf2123_delay_trec();
 104         return sprintf(buffer, "0x%x\n", rxbuf[0]);
 105 }
 106
 107 static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
 108                              const char *buffer, size_t count) {
 109         struct spi_device *spi = to_spi_device(dev);
 110         struct pcf2123_sysfs_reg *r;
 111         u8 txbuf[2];
 112         unsigned long reg;
 113         unsigned long val;
 114
 115         int ret;
 116
 117         r = container_of(attr, struct pcf2123_sysfs_reg, attr);
 118
 119         if (strict_strtoul(r->name, 16, &reg)
 120                 || strict_strtoul(buffer, 10, &val))
 121                 return -EINVAL;
 122
 123         txbuf[0] = PCF2123_WRITE | reg;
 124         txbuf[1] = val;
 125         ret = spi_write(spi, txbuf, sizeof(txbuf));
 126         if (ret < 0)
 127                 return -EIO;
 128         pcf2123_delay_trec();
 129         return count;
 130 }
 131
 132 static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
 133 {
 134         struct spi_device *spi = to_spi_device(dev);
 135         u8 txbuf[1], rxbuf[7];
 136         int ret;
 137
 138         txbuf[0] = PCF2123_READ | PCF2123_REG_SC;
 139         ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
 140                         rxbuf, sizeof(rxbuf));
 141         if (ret < 0)
 142                 return ret;
 143         pcf2123_delay_trec();
 144
 145         tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
 146         tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
 147         tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
 148         tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
 149         tm->tm_wday = rxbuf[4] & 0x07;
 150         tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
 151         tm->tm_year = bcd2bin(rxbuf[6]);
 152         if (tm->tm_year < 70)
 153                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 154
 155         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 156                         "mday=%d, mon=%d, year=%d, wday=%d\n",
 157                         __func__,
 158                         tm->tm_sec, tm->tm_min, tm->tm_hour,
 159                         tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 160
 161         /* the clock can give out invalid datetime, but we cannot return
 162          * -EINVAL otherwise hwclock will refuse to set the time on bootup.
 163          */
 164         if (rtc_valid_tm(tm) < 0)
 165                 dev_err(dev, "retrieved date/time is not valid.\n");
 166
 167         return 0;
 168 }
 169
 170 static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
 171 {
 172         struct spi_device *spi = to_spi_device(dev);
 173         u8 txbuf[8];
 174         int ret;
 175
 176         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 177                         "mday=%d, mon=%d, year=%d, wday=%d\n",
 178                         __func__,
 179                         tm->tm_sec, tm->tm_min, tm->tm_hour,
 180                         tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 181
 182         /* Stop the counter first */
 183         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 184         txbuf[1] = 0x20;
 185         ret = spi_write(spi, txbuf, 2);
 186         if (ret < 0)
 187                 return ret;
 188         pcf2123_delay_trec();
 189
 190         /* Set the new time */
 191         txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
 192         txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
 193         txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
 194         txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
 195         txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
 196         txbuf[5] = tm->tm_wday & 0x07;
 197         txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
 198         txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);
 199
 200         ret = spi_write(spi, txbuf, sizeof(txbuf));
 201         if (ret < 0)
 202                 return ret;
 203         pcf2123_delay_trec();
 204
 205         /* Start the counter */
 206         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 207         txbuf[1] = 0x00;
 208         ret = spi_write(spi, txbuf, 2);
 209         if (ret < 0)
 210                 return ret;
 211         pcf2123_delay_trec();
 212
 213         return 0;
 214 }
 215
 216 static const struct rtc_class_ops pcf2123_rtc_ops = {
 217         .read_time      = pcf2123_rtc_read_time,
 218         .set_time       = pcf2123_rtc_set_time,
 219 };
 220
 221 static int __devinit pcf2123_probe(struct spi_device *spi)
 222 {
 223         struct rtc_device *rtc;
 224         struct pcf2123_plat_data *pdata;
 225         u8 txbuf[2], rxbuf[2];
 226         int ret, i;
 227
 228         pdata = kzalloc(sizeof(struct pcf2123_plat_data), GFP_KERNEL);
 229         if (!pdata)
 230                 return -ENOMEM;
 231         spi->dev.platform_data = pdata;
 232
 233         /* Send a software reset command */
 234         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 235         txbuf[1] = 0x58;
 236         dev_dbg(&spi->dev, "resetting RTC (0x%02X 0x%02X)\n",
 237                         txbuf[0], txbuf[1]);
 238         ret = spi_write(spi, txbuf, 2 * sizeof(u8));
 239         if (ret < 0)
 240                 goto kfree_exit;
 241         pcf2123_delay_trec();
 242
 243         /* Stop the counter */
 244         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 245         txbuf[1] = 0x20;
 246         dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)\n",
 247                         txbuf[0], txbuf[1]);
 248         ret = spi_write(spi, txbuf, 2 * sizeof(u8));
 249         if (ret < 0)
 250                 goto kfree_exit;
 251         pcf2123_delay_trec();
 252
 253         /* See if the counter was actually stopped */
 254         txbuf[0] = PCF2123_READ | PCF2123_REG_CTRL1;
 255         dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)\n",
 256                         txbuf[0]);
 257         ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
 258                                         rxbuf, 2 * sizeof(u8));
 259         dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)\n",
 260                         rxbuf[0], rxbuf[1]);
 261         if (ret < 0)
 262                 goto kfree_exit;
 263         pcf2123_delay_trec();
 264
 265         if (!(rxbuf[0] & 0x20)) {
 266                 dev_err(&spi->dev, "chip not found\n");
 267                 goto kfree_exit;
 268         }
 269
 270         dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
 271         dev_info(&spi->dev, "spiclk %u KHz.\n",
 272                         (spi->max_speed_hz + 500) / 1000);
 273
 274         /* Start the counter */
 275         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 276         txbuf[1] = 0x00;
 277         ret = spi_write(spi, txbuf, sizeof(txbuf));
 278         if (ret < 0)
 279                 goto kfree_exit;
 280         pcf2123_delay_trec();
 281
 282         /* Finalize the initialization */
 283         rtc = rtc_device_register(pcf2123_driver.driver.name, &spi->dev,
 284                         &pcf2123_rtc_ops, THIS_MODULE);
 285
 286         if (IS_ERR(rtc)) {
 287                 dev_err(&spi->dev, "failed to register.\n");
 288                 ret = PTR_ERR(rtc);
 289                 goto kfree_exit;
 290         }
 291
 292         pdata->rtc = rtc;
 293
 294         for (i = 0; i < 16; i++) {
 295                 sprintf(pdata->regs[i].name, "%1x", i);
 296                 pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
 297                 pdata->regs[i].attr.attr.name = pdata->regs[i].name;
 298                 pdata->regs[i].attr.show = pcf2123_show;
 299                 pdata->regs[i].attr.store = pcf2123_store;
 300                 ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
 301                 if (ret) {
 302                         dev_err(&spi->dev, "Unable to create sysfs %s\n",
 303                                 pdata->regs[i].name);
 304                         goto sysfs_exit;
 305                 }
 306         }
 307
 308         return 0;
 309
 310 sysfs_exit:
 311         for (i--; i >= 0; i--)
 312                 device_remove_file(&spi->dev, &pdata->regs[i].attr);
 313
 314 kfree_exit:
 315         kfree(pdata);
 316         spi->dev.platform_data = NULL;
 317         return ret;
 318 }
 319
 320 static int __devexit pcf2123_remove(struct spi_device *spi)
 321 {
 322         struct pcf2123_plat_data *pdata = spi->dev.platform_data;
 323         int i;
 324
 325         if (pdata) {
 326                 struct rtc_device *rtc = pdata->rtc;
 327
 328                 if (rtc)
 329                         rtc_device_unregister(rtc);
 330                 for (i = 0; i < 16; i++)
 331                         if (pdata->regs[i].name[0])
 332                                 device_remove_file(&spi->dev,
 333                                                    &pdata->regs[i].attr);
 334                 kfree(pdata);
 335         }
 336
 337         return 0;
 338 }
 339
 340 static struct spi_driver pcf2123_driver = {
 341         .driver = {
 342                         .name   = "rtc-pcf2123",
 343                         .owner  = THIS_MODULE,
 344         },
 345         .probe  = pcf2123_probe,
 346         .remove = __devexit_p(pcf2123_remove),
 347 };
 348
 349 module_spi_driver(pcf2123_driver);
 350
 351 MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
 352 MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
 353 MODULE_LICENSE("GPL");
 354 MODULE_VERSION(DRV_VERSION);