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/rtc.h>
  43 #include <linux/spi/spi.h>
  44
  45 #define DRV_VERSION "0.6"
  46
  47 #define PCF2123_REG_CTRL1       (0x00)  /* Control Register 1 */
  48 #define PCF2123_REG_CTRL2       (0x01)  /* Control Register 2 */
  49 #define PCF2123_REG_SC          (0x02)  /* datetime */
  50 #define PCF2123_REG_MN          (0x03)
  51 #define PCF2123_REG_HR          (0x04)
  52 #define PCF2123_REG_DM          (0x05)
  53 #define PCF2123_REG_DW          (0x06)
  54 #define PCF2123_REG_MO          (0x07)
  55 #define PCF2123_REG_YR          (0x08)
  56
  57 #define PCF2123_SUBADDR         (1 << 4)
  58 #define PCF2123_WRITE           ((0 << 7) | PCF2123_SUBADDR)
  59 #define PCF2123_READ            ((1 << 7) | PCF2123_SUBADDR)
  60
  61 static struct spi_driver pcf2123_driver;
  62
  63 struct pcf2123_sysfs_reg {
  64         struct device_attribute attr;
  65         char name[2];
  66 };
  67
  68 struct pcf2123_plat_data {
  69         struct rtc_device *rtc;
  70         struct pcf2123_sysfs_reg regs[16];
  71 };
  72
  73 /*
  74  * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
  75  * is released properly after an SPI write.  This function should be
  76  * called after EVERY read/write call over SPI.
  77  */
  78 static inline void pcf2123_delay_trec(void)
  79 {
  80         ndelay(30);
  81 }
  82
  83 static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
  84                             char *buffer)
  85 {
  86         struct spi_device *spi = to_spi_device(dev);
  87         struct pcf2123_sysfs_reg *r;
  88         u8 txbuf[1], rxbuf[1];
  89         unsigned long reg;
  90         int ret;
  91
  92         r = container_of(attr, struct pcf2123_sysfs_reg, attr);
  93
  94         if (strict_strtoul(r->name, 16, &reg))
  95                 return -EINVAL;
  96
  97         txbuf[0] = PCF2123_READ | reg;
  98         ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
  99         if (ret < 0)
 100                 return -EIO;
 101         pcf2123_delay_trec();
 102         return sprintf(buffer, "0x%x\n", rxbuf[0]);
 103 }
 104
 105 static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
 106                              const char *buffer, size_t count) {
 107         struct spi_device *spi = to_spi_device(dev);
 108         struct pcf2123_sysfs_reg *r;
 109         u8 txbuf[2];
 110         unsigned long reg;
 111         unsigned long val;
 112
 113         int ret;
 114
 115         r = container_of(attr, struct pcf2123_sysfs_reg, attr);
 116
 117         if (strict_strtoul(r->name, 16, &reg)
 118                 || strict_strtoul(buffer, 10, &val))
 119                 return -EINVAL;
 120
 121         txbuf[0] = PCF2123_WRITE | reg;
 122         txbuf[1] = val;
 123         ret = spi_write(spi, txbuf, sizeof(txbuf));
 124         if (ret < 0)
 125                 return -EIO;
 126         pcf2123_delay_trec();
 127         return count;
 128 }
 129
 130 static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
 131 {
 132         struct spi_device *spi = to_spi_device(dev);
 133         u8 txbuf[1], rxbuf[7];
 134         int ret;
 135
 136         txbuf[0] = PCF2123_READ | PCF2123_REG_SC;
 137         ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
 138                         rxbuf, sizeof(rxbuf));
 139         if (ret < 0)
 140                 return ret;
 141         pcf2123_delay_trec();
 142
 143         tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
 144         tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
 145         tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
 146         tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
 147         tm->tm_wday = rxbuf[4] & 0x07;
 148         tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
 149         tm->tm_year = bcd2bin(rxbuf[6]);
 150         if (tm->tm_year < 70)
 151                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 152
 153         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 154                         "mday=%d, mon=%d, year=%d, wday=%d\n",
 155                         __func__,
 156                         tm->tm_sec, tm->tm_min, tm->tm_hour,
 157                         tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 158
 159         /* the clock can give out invalid datetime, but we cannot return
 160          * -EINVAL otherwise hwclock will refuse to set the time on bootup.
 161          */
 162         if (rtc_valid_tm(tm) < 0)
 163                 dev_err(dev, "retrieved date/time is not valid.\n");
 164
 165         return 0;
 166 }
 167
 168 static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
 169 {
 170         struct spi_device *spi = to_spi_device(dev);
 171         u8 txbuf[8];
 172         int ret;
 173
 174         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 175                         "mday=%d, mon=%d, year=%d, wday=%d\n",
 176                         __func__,
 177                         tm->tm_sec, tm->tm_min, tm->tm_hour,
 178                         tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 179
 180         /* Stop the counter first */
 181         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 182         txbuf[1] = 0x20;
 183         ret = spi_write(spi, txbuf, 2);
 184         if (ret < 0)
 185                 return ret;
 186         pcf2123_delay_trec();
 187
 188         /* Set the new time */
 189         txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
 190         txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
 191         txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
 192         txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
 193         txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
 194         txbuf[5] = tm->tm_wday & 0x07;
 195         txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
 196         txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);
 197
 198         ret = spi_write(spi, txbuf, sizeof(txbuf));
 199         if (ret < 0)
 200                 return ret;
 201         pcf2123_delay_trec();
 202
 203         /* Start the counter */
 204         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 205         txbuf[1] = 0x00;
 206         ret = spi_write(spi, txbuf, 2);
 207         if (ret < 0)
 208                 return ret;
 209         pcf2123_delay_trec();
 210
 211         return 0;
 212 }
 213
 214 static const struct rtc_class_ops pcf2123_rtc_ops = {
 215         .read_time      = pcf2123_rtc_read_time,
 216         .set_time       = pcf2123_rtc_set_time,
 217 };
 218
 219 static int __devinit pcf2123_probe(struct spi_device *spi)
 220 {
 221         struct rtc_device *rtc;
 222         struct pcf2123_plat_data *pdata;
 223         u8 txbuf[2], rxbuf[2];
 224         int ret, i;
 225
 226         pdata = kzalloc(sizeof(struct pcf2123_plat_data), GFP_KERNEL);
 227         if (!pdata)
 228                 return -ENOMEM;
 229         spi->dev.platform_data = pdata;
 230
 231         /* Send a software reset command */
 232         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 233         txbuf[1] = 0x58;
 234         dev_dbg(&spi->dev, "resetting RTC (0x%02X 0x%02X)\n",
 235                         txbuf[0], txbuf[1]);
 236         ret = spi_write(spi, txbuf, 2 * sizeof(u8));
 237         if (ret < 0)
 238                 goto kfree_exit;
 239         pcf2123_delay_trec();
 240
 241         /* Stop the counter */
 242         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 243         txbuf[1] = 0x20;
 244         dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)\n",
 245                         txbuf[0], txbuf[1]);
 246         ret = spi_write(spi, txbuf, 2 * sizeof(u8));
 247         if (ret < 0)
 248                 goto kfree_exit;
 249         pcf2123_delay_trec();
 250
 251         /* See if the counter was actually stopped */
 252         txbuf[0] = PCF2123_READ | PCF2123_REG_CTRL1;
 253         dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)\n",
 254                         txbuf[0]);
 255         ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
 256                                         rxbuf, 2 * sizeof(u8));
 257         dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)\n",
 258                         rxbuf[0], rxbuf[1]);
 259         if (ret < 0)
 260                 goto kfree_exit;
 261         pcf2123_delay_trec();
 262
 263         if (!(rxbuf[0] & 0x20)) {
 264                 dev_err(&spi->dev, "chip not found\n");
 265                 goto kfree_exit;
 266         }
 267
 268         dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
 269         dev_info(&spi->dev, "spiclk %u KHz.\n",
 270                         (spi->max_speed_hz + 500) / 1000);
 271
 272         /* Start the counter */
 273         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 274         txbuf[1] = 0x00;
 275         ret = spi_write(spi, txbuf, sizeof(txbuf));
 276         if (ret < 0)
 277                 goto kfree_exit;
 278         pcf2123_delay_trec();
 279
 280         /* Finalize the initialization */
 281         rtc = rtc_device_register(pcf2123_driver.driver.name, &spi->dev,
 282                         &pcf2123_rtc_ops, THIS_MODULE);
 283
 284         if (IS_ERR(rtc)) {
 285                 dev_err(&spi->dev, "failed to register.\n");
 286                 ret = PTR_ERR(rtc);
 287                 goto kfree_exit;
 288         }
 289
 290         pdata->rtc = rtc;
 291
 292         for (i = 0; i < 16; i++) {
 293                 sprintf(pdata->regs[i].name, "%1x", i);
 294                 pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
 295                 pdata->regs[i].attr.attr.name = pdata->regs[i].name;
 296                 pdata->regs[i].attr.show = pcf2123_show;
 297                 pdata->regs[i].attr.store = pcf2123_store;
 298                 ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
 299                 if (ret) {
 300                         dev_err(&spi->dev, "Unable to create sysfs %s\n",
 301                                 pdata->regs[i].name);
 302                         goto sysfs_exit;
 303                 }
 304         }
 305
 306         return 0;
 307
 308 sysfs_exit:
 309         for (i--; i >= 0; i--)
 310                 device_remove_file(&spi->dev, &pdata->regs[i].attr);
 311
 312 kfree_exit:
 313         kfree(pdata);
 314         spi->dev.platform_data = NULL;
 315         return ret;
 316 }
 317
 318 static int pcf2123_remove(struct spi_device *spi)
 319 {
 320         struct pcf2123_plat_data *pdata = spi->dev.platform_data;
 321         int i;
 322
 323         if (pdata) {
 324                 struct rtc_device *rtc = pdata->rtc;
 325
 326                 if (rtc)
 327                         rtc_device_unregister(rtc);
 328                 for (i = 0; i < 16; i++)
 329                         if (pdata->regs[i].name[0])
 330                                 device_remove_file(&spi->dev,
 331                                                    &pdata->regs[i].attr);
 332                 kfree(pdata);
 333         }
 334
 335         return 0;
 336 }
 337
 338 static struct spi_driver pcf2123_driver = {
 339         .driver = {
 340                         .name   = "rtc-pcf2123",
 341                         .bus    = &spi_bus_type,
 342                         .owner  = THIS_MODULE,
 343         },
 344         .probe  = pcf2123_probe,
 345         .remove = __devexit_p(pcf2123_remove),
 346 };
 347
 348 static int __init pcf2123_init(void)
 349 {
 350         return spi_register_driver(&pcf2123_driver);
 351 }
 352
 353 static void __exit pcf2123_exit(void)
 354 {
 355         spi_unregister_driver(&pcf2123_driver);
 356 }
 357
 358 MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
 359 MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
 360 MODULE_LICENSE("GPL");
 361 MODULE_VERSION(DRV_VERSION);
 362
 363 module_init(pcf2123_init);
 364 module_exit(pcf2123_exit);