linux/drivers/rtc/rtc-pcf2123.c
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   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
  63static struct spi_driver pcf2123_driver;
  64
  65struct pcf2123_sysfs_reg {
  66        struct device_attribute attr;
  67        char name[2];
  68};
  69
  70struct 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 */
  80static inline void pcf2123_delay_trec(void)
  81{
  82        ndelay(30);
  83}
  84
  85static 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
 107static 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
 132static 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
 170static 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
 216static const struct rtc_class_ops pcf2123_rtc_ops = {
 217        .read_time      = pcf2123_rtc_read_time,
 218        .set_time       = pcf2123_rtc_set_time,
 219};
 220
 221static 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
 310sysfs_exit:
 311        for (i--; i >= 0; i--)
 312                device_remove_file(&spi->dev, &pdata->regs[i].attr);
 313
 314kfree_exit:
 315        kfree(pdata);
 316        spi->dev.platform_data = NULL;
 317        return ret;
 318}
 319
 320static 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
 340static 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
 349static int __init pcf2123_init(void)
 350{
 351        return spi_register_driver(&pcf2123_driver);
 352}
 353
 354static void __exit pcf2123_exit(void)
 355{
 356        spi_unregister_driver(&pcf2123_driver);
 357}
 358
 359MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
 360MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
 361MODULE_LICENSE("GPL");
 362MODULE_VERSION(DRV_VERSION);
 363
 364module_init(pcf2123_init);
 365module_exit(pcf2123_exit);
 366