kernel/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/of.h>
  42 #include <linux/string.h>
  43 #include <linux/slab.h>
  44 #include <linux/rtc.h>
  45 #include <linux/spi/spi.h>
  46 #include <linux/module.h>
  47 #include <linux/sysfs.h>
  48
  49 #define DRV_VERSION "0.6"
  50
  51 #define PCF2123_REG_CTRL1       (0x00)  /* Control Register 1 */
  52 #define PCF2123_REG_CTRL2       (0x01)  /* Control Register 2 */
  53 #define PCF2123_REG_SC          (0x02)  /* datetime */
  54 #define PCF2123_REG_MN          (0x03)
  55 #define PCF2123_REG_HR          (0x04)
  56 #define PCF2123_REG_DM          (0x05)
  57 #define PCF2123_REG_DW          (0x06)
  58 #define PCF2123_REG_MO          (0x07)
  59 #define PCF2123_REG_YR          (0x08)
  60
  61 #define PCF2123_SUBADDR         (1 << 4)
  62 #define PCF2123_WRITE           ((0 << 7) | PCF2123_SUBADDR)
  63 #define PCF2123_READ            ((1 << 7) | PCF2123_SUBADDR)
  64
  65 static struct spi_driver pcf2123_driver;
  66
  67 struct pcf2123_sysfs_reg {
  68         struct device_attribute attr;
  69         char name[2];
  70 };
  71
  72 struct pcf2123_plat_data {
  73         struct rtc_device *rtc;
  74         struct pcf2123_sysfs_reg regs[16];
  75 };
  76
  77 /*
  78  * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
  79  * is released properly after an SPI write.  This function should be
  80  * called after EVERY read/write call over SPI.
  81  */
  82 static inline void pcf2123_delay_trec(void)
  83 {
  84         ndelay(30);
  85 }
  86
  87 static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
  88                             char *buffer)
  89 {
  90         struct spi_device *spi = to_spi_device(dev);
  91         struct pcf2123_sysfs_reg *r;
  92         u8 txbuf[1], rxbuf[1];
  93         unsigned long reg;
  94         int ret;
  95
  96         r = container_of(attr, struct pcf2123_sysfs_reg, attr);
  97
  98         ret = kstrtoul(r->name, 16, &reg);
  99         if (ret)
 100                 return ret;
 101
 102         txbuf[0] = PCF2123_READ | reg;
 103         ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
 104         if (ret < 0)
 105                 return -EIO;
 106         pcf2123_delay_trec();
 107         return sprintf(buffer, "0x%x\n", rxbuf[0]);
 108 }
 109
 110 static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
 111                              const char *buffer, size_t count) {
 112         struct spi_device *spi = to_spi_device(dev);
 113         struct pcf2123_sysfs_reg *r;
 114         u8 txbuf[2];
 115         unsigned long reg;
 116         unsigned long val;
 117
 118         int ret;
 119
 120         r = container_of(attr, struct pcf2123_sysfs_reg, attr);
 121
 122         ret = kstrtoul(r->name, 16, &reg);
 123         if (ret)
 124                 return ret;
 125
 126         ret = kstrtoul(buffer, 10, &val);
 127         if (ret)
 128                 return ret;
 129
 130         txbuf[0] = PCF2123_WRITE | reg;
 131         txbuf[1] = val;
 132         ret = spi_write(spi, txbuf, sizeof(txbuf));
 133         if (ret < 0)
 134                 return -EIO;
 135         pcf2123_delay_trec();
 136         return count;
 137 }
 138
 139 static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
 140 {
 141         struct spi_device *spi = to_spi_device(dev);
 142         u8 txbuf[1], rxbuf[7];
 143         int ret;
 144
 145         txbuf[0] = PCF2123_READ | PCF2123_REG_SC;
 146         ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
 147                         rxbuf, sizeof(rxbuf));
 148         if (ret < 0)
 149                 return ret;
 150         pcf2123_delay_trec();
 151
 152         tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
 153         tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
 154         tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
 155         tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
 156         tm->tm_wday = rxbuf[4] & 0x07;
 157         tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
 158         tm->tm_year = bcd2bin(rxbuf[6]);
 159         if (tm->tm_year < 70)
 160                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 161
 162         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 163                         "mday=%d, mon=%d, year=%d, wday=%d\n",
 164                         __func__,
 165                         tm->tm_sec, tm->tm_min, tm->tm_hour,
 166                         tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 167
 168         /* the clock can give out invalid datetime, but we cannot return
 169          * -EINVAL otherwise hwclock will refuse to set the time on bootup.
 170          */
 171         if (rtc_valid_tm(tm) < 0)
 172                 dev_err(dev, "retrieved date/time is not valid.\n");
 173
 174         return 0;
 175 }
 176
 177 static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
 178 {
 179         struct spi_device *spi = to_spi_device(dev);
 180         u8 txbuf[8];
 181         int ret;
 182
 183         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 184                         "mday=%d, mon=%d, year=%d, wday=%d\n",
 185                         __func__,
 186                         tm->tm_sec, tm->tm_min, tm->tm_hour,
 187                         tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 188
 189         /* Stop the counter first */
 190         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 191         txbuf[1] = 0x20;
 192         ret = spi_write(spi, txbuf, 2);
 193         if (ret < 0)
 194                 return ret;
 195         pcf2123_delay_trec();
 196
 197         /* Set the new time */
 198         txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
 199         txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
 200         txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
 201         txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
 202         txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
 203         txbuf[5] = tm->tm_wday & 0x07;
 204         txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
 205         txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);
 206
 207         ret = spi_write(spi, txbuf, sizeof(txbuf));
 208         if (ret < 0)
 209                 return ret;
 210         pcf2123_delay_trec();
 211
 212         /* Start the counter */
 213         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 214         txbuf[1] = 0x00;
 215         ret = spi_write(spi, txbuf, 2);
 216         if (ret < 0)
 217                 return ret;
 218         pcf2123_delay_trec();
 219
 220         return 0;
 221 }
 222
 223 static const struct rtc_class_ops pcf2123_rtc_ops = {
 224         .read_time      = pcf2123_rtc_read_time,
 225         .set_time       = pcf2123_rtc_set_time,
 226 };
 227
 228 static int pcf2123_probe(struct spi_device *spi)
 229 {
 230         struct rtc_device *rtc;
 231         struct pcf2123_plat_data *pdata;
 232         u8 txbuf[2], rxbuf[2];
 233         int ret, i;
 234
 235         pdata = devm_kzalloc(&spi->dev, sizeof(struct pcf2123_plat_data),
 236                                 GFP_KERNEL);
 237         if (!pdata)
 238                 return -ENOMEM;
 239         spi->dev.platform_data = pdata;
 240
 241         /* Send a software reset command */
 242         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 243         txbuf[1] = 0x58;
 244         dev_dbg(&spi->dev, "resetting 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         /* Stop the counter */
 252         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 253         txbuf[1] = 0x20;
 254         dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)\n",
 255                         txbuf[0], txbuf[1]);
 256         ret = spi_write(spi, txbuf, 2 * sizeof(u8));
 257         if (ret < 0)
 258                 goto kfree_exit;
 259         pcf2123_delay_trec();
 260
 261         /* See if the counter was actually stopped */
 262         txbuf[0] = PCF2123_READ | PCF2123_REG_CTRL1;
 263         dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)\n",
 264                         txbuf[0]);
 265         ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
 266                                         rxbuf, 2 * sizeof(u8));
 267         dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)\n",
 268                         rxbuf[0], rxbuf[1]);
 269         if (ret < 0)
 270                 goto kfree_exit;
 271         pcf2123_delay_trec();
 272
 273         if (!(rxbuf[0] & 0x20)) {
 274                 dev_err(&spi->dev, "chip not found\n");
 275                 ret = -ENODEV;
 276                 goto kfree_exit;
 277         }
 278
 279         dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
 280         dev_info(&spi->dev, "spiclk %u KHz.\n",
 281                         (spi->max_speed_hz + 500) / 1000);
 282
 283         /* Start the counter */
 284         txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 285         txbuf[1] = 0x00;
 286         ret = spi_write(spi, txbuf, sizeof(txbuf));
 287         if (ret < 0)
 288                 goto kfree_exit;
 289         pcf2123_delay_trec();
 290
 291         /* Finalize the initialization */
 292         rtc = devm_rtc_device_register(&spi->dev, pcf2123_driver.driver.name,
 293                         &pcf2123_rtc_ops, THIS_MODULE);
 294
 295         if (IS_ERR(rtc)) {
 296                 dev_err(&spi->dev, "failed to register.\n");
 297                 ret = PTR_ERR(rtc);
 298                 goto kfree_exit;
 299         }
 300
 301         pdata->rtc = rtc;
 302
 303         for (i = 0; i < 16; i++) {
 304                 sysfs_attr_init(&pdata->regs[i].attr.attr);
 305                 sprintf(pdata->regs[i].name, "%1x", i);
 306                 pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
 307                 pdata->regs[i].attr.attr.name = pdata->regs[i].name;
 308                 pdata->regs[i].attr.show = pcf2123_show;
 309                 pdata->regs[i].attr.store = pcf2123_store;
 310                 ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
 311                 if (ret) {
 312                         dev_err(&spi->dev, "Unable to create sysfs %s\n",
 313                                 pdata->regs[i].name);
 314                         goto sysfs_exit;
 315                 }
 316         }
 317
 318         return 0;
 319
 320 sysfs_exit:
 321         for (i--; i >= 0; i--)
 322                 device_remove_file(&spi->dev, &pdata->regs[i].attr);
 323
 324 kfree_exit:
 325         spi->dev.platform_data = NULL;
 326         return ret;
 327 }
 328
 329 static int pcf2123_remove(struct spi_device *spi)
 330 {
 331         struct pcf2123_plat_data *pdata = dev_get_platdata(&spi->dev);
 332         int i;
 333
 334         if (pdata) {
 335                 for (i = 0; i < 16; i++)
 336                         if (pdata->regs[i].name[0])
 337                                 device_remove_file(&spi->dev,
 338                                                    &pdata->regs[i].attr);
 339         }
 340
 341         return 0;
 342 }
 343
 344 #ifdef CONFIG_OF
 345 static const struct of_device_id pcf2123_dt_ids[] = {
 346         { .compatible = "nxp,rtc-pcf2123", },
 347         { /* sentinel */ }
 348 };
 349 MODULE_DEVICE_TABLE(of, pcf2123_dt_ids);
 350 #endif
 351
 352 static struct spi_driver pcf2123_driver = {
 353         .driver = {
 354                         .name   = "rtc-pcf2123",
 355                         .owner  = THIS_MODULE,
 356                         .of_match_table = of_match_ptr(pcf2123_dt_ids),
 357         },
 358         .probe  = pcf2123_probe,
 359         .remove = pcf2123_remove,
 360 };
 361
 362 module_spi_driver(pcf2123_driver);
 363
 364 MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
 365 MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
 366 MODULE_LICENSE("GPL");
 367 MODULE_VERSION(DRV_VERSION);