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