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