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