drivers/rtc/rtc-stk17ta8.c

   1 /*
   2  * A RTC driver for the Simtek STK17TA8
   3  *
   4  * By Thomas Hommel <thomas.hommel@ge.com>
   5  *
   6  * Based on the DS1553 driver from
   7  * Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/bcd.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/gfp.h>
  18 #include <linux/delay.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/rtc.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/io.h>
  24 #include <linux/module.h>
  25
  26 #define RTC_REG_SIZE            0x20000
  27 #define RTC_OFFSET              0x1fff0
  28
  29 #define RTC_FLAGS               (RTC_OFFSET + 0)
  30 #define RTC_CENTURY             (RTC_OFFSET + 1)
  31 #define RTC_SECONDS_ALARM       (RTC_OFFSET + 2)
  32 #define RTC_MINUTES_ALARM       (RTC_OFFSET + 3)
  33 #define RTC_HOURS_ALARM         (RTC_OFFSET + 4)
  34 #define RTC_DATE_ALARM          (RTC_OFFSET + 5)
  35 #define RTC_INTERRUPTS          (RTC_OFFSET + 6)
  36 #define RTC_WATCHDOG            (RTC_OFFSET + 7)
  37 #define RTC_CALIBRATION         (RTC_OFFSET + 8)
  38 #define RTC_SECONDS             (RTC_OFFSET + 9)
  39 #define RTC_MINUTES             (RTC_OFFSET + 10)
  40 #define RTC_HOURS               (RTC_OFFSET + 11)
  41 #define RTC_DAY                 (RTC_OFFSET + 12)
  42 #define RTC_DATE                (RTC_OFFSET + 13)
  43 #define RTC_MONTH               (RTC_OFFSET + 14)
  44 #define RTC_YEAR                (RTC_OFFSET + 15)
  45
  46 #define RTC_SECONDS_MASK        0x7f
  47 #define RTC_DAY_MASK            0x07
  48 #define RTC_CAL_MASK            0x3f
  49
  50 /* Bits in the Calibration register */
  51 #define RTC_STOP                0x80
  52
  53 /* Bits in the Flags register */
  54 #define RTC_FLAGS_AF            0x40
  55 #define RTC_FLAGS_PF            0x20
  56 #define RTC_WRITE               0x02
  57 #define RTC_READ                0x01
  58
  59 /* Bits in the Interrupts register */
  60 #define RTC_INTS_AIE            0x40
  61
  62 struct rtc_plat_data {
  63         struct rtc_device *rtc;
  64         void __iomem *ioaddr;
  65         unsigned long last_jiffies;
  66         int irq;
  67         unsigned int irqen;
  68         int alrm_sec;
  69         int alrm_min;
  70         int alrm_hour;
  71         int alrm_mday;
  72         spinlock_t lock;
  73 };
  74
  75 static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
  76 {
  77         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
  78         void __iomem *ioaddr = pdata->ioaddr;
  79         u8 flags;
  80
  81         flags = readb(pdata->ioaddr + RTC_FLAGS);
  82         writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
  83
  84         writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
  85         writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
  86         writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
  87         writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
  88         writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
  89         writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
  90         writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
  91         writeb(bin2bcd((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY);
  92
  93         writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
  94         return 0;
  95 }
  96
  97 static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm)
  98 {
  99         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 100         void __iomem *ioaddr = pdata->ioaddr;
 101         unsigned int year, month, day, hour, minute, second, week;
 102         unsigned int century;
 103         u8 flags;
 104
 105         /* give enough time to update RTC in case of continuous read */
 106         if (pdata->last_jiffies == jiffies)
 107                 msleep(1);
 108         pdata->last_jiffies = jiffies;
 109
 110         flags = readb(pdata->ioaddr + RTC_FLAGS);
 111         writeb(flags | RTC_READ, ioaddr + RTC_FLAGS);
 112         second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
 113         minute = readb(ioaddr + RTC_MINUTES);
 114         hour = readb(ioaddr + RTC_HOURS);
 115         day = readb(ioaddr + RTC_DATE);
 116         week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
 117         month = readb(ioaddr + RTC_MONTH);
 118         year = readb(ioaddr + RTC_YEAR);
 119         century = readb(ioaddr + RTC_CENTURY);
 120         writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS);
 121         tm->tm_sec = bcd2bin(second);
 122         tm->tm_min = bcd2bin(minute);
 123         tm->tm_hour = bcd2bin(hour);
 124         tm->tm_mday = bcd2bin(day);
 125         tm->tm_wday = bcd2bin(week);
 126         tm->tm_mon = bcd2bin(month) - 1;
 127         /* year is 1900 + tm->tm_year */
 128         tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
 129
 130         return 0;
 131 }
 132
 133 static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
 134 {
 135         void __iomem *ioaddr = pdata->ioaddr;
 136         unsigned long irqflags;
 137         u8 flags;
 138
 139         spin_lock_irqsave(&pdata->lock, irqflags);
 140
 141         flags = readb(ioaddr + RTC_FLAGS);
 142         writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
 143
 144         writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
 145                0x80 : bin2bcd(pdata->alrm_mday),
 146                ioaddr + RTC_DATE_ALARM);
 147         writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
 148                0x80 : bin2bcd(pdata->alrm_hour),
 149                ioaddr + RTC_HOURS_ALARM);
 150         writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
 151                0x80 : bin2bcd(pdata->alrm_min),
 152                ioaddr + RTC_MINUTES_ALARM);
 153         writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
 154                0x80 : bin2bcd(pdata->alrm_sec),
 155                ioaddr + RTC_SECONDS_ALARM);
 156         writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS);
 157         readb(ioaddr + RTC_FLAGS);      /* clear interrupts */
 158         writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
 159         spin_unlock_irqrestore(&pdata->lock, irqflags);
 160 }
 161
 162 static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 163 {
 164         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 165
 166         if (pdata->irq <= 0)
 167                 return -EINVAL;
 168         pdata->alrm_mday = alrm->time.tm_mday;
 169         pdata->alrm_hour = alrm->time.tm_hour;
 170         pdata->alrm_min = alrm->time.tm_min;
 171         pdata->alrm_sec = alrm->time.tm_sec;
 172         if (alrm->enabled)
 173                 pdata->irqen |= RTC_AF;
 174         stk17ta8_rtc_update_alarm(pdata);
 175         return 0;
 176 }
 177
 178 static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 179 {
 180         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 181
 182         if (pdata->irq <= 0)
 183                 return -EINVAL;
 184         alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
 185         alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
 186         alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
 187         alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
 188         alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
 189         return 0;
 190 }
 191
 192 static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id)
 193 {
 194         struct platform_device *pdev = dev_id;
 195         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 196         void __iomem *ioaddr = pdata->ioaddr;
 197         unsigned long events = 0;
 198
 199         spin_lock(&pdata->lock);
 200         /* read and clear interrupt */
 201         if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
 202                 events = RTC_IRQF;
 203                 if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
 204                         events |= RTC_UF;
 205                 else
 206                         events |= RTC_AF;
 207                 rtc_update_irq(pdata->rtc, 1, events);
 208         }
 209         spin_unlock(&pdata->lock);
 210         return events ? IRQ_HANDLED : IRQ_NONE;
 211 }
 212
 213 static int stk17ta8_rtc_alarm_irq_enable(struct device *dev,
 214         unsigned int enabled)
 215 {
 216         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 217
 218         if (pdata->irq <= 0)
 219                 return -EINVAL;
 220         if (enabled)
 221                 pdata->irqen |= RTC_AF;
 222         else
 223                 pdata->irqen &= ~RTC_AF;
 224         stk17ta8_rtc_update_alarm(pdata);
 225         return 0;
 226 }
 227
 228 static const struct rtc_class_ops stk17ta8_rtc_ops = {
 229         .read_time              = stk17ta8_rtc_read_time,
 230         .set_time               = stk17ta8_rtc_set_time,
 231         .read_alarm             = stk17ta8_rtc_read_alarm,
 232         .set_alarm              = stk17ta8_rtc_set_alarm,
 233         .alarm_irq_enable       = stk17ta8_rtc_alarm_irq_enable,
 234 };
 235
 236 static int stk17ta8_nvram_read(void *priv, unsigned int pos, void *val,
 237                                size_t bytes)
 238 {
 239         struct rtc_plat_data *pdata = priv;
 240         void __iomem *ioaddr = pdata->ioaddr;
 241         u8 *buf = val;
 242
 243         for (; bytes; bytes--)
 244                 *buf++ = readb(ioaddr + pos++);
 245         return 0;
 246 }
 247
 248 static int stk17ta8_nvram_write(void *priv, unsigned int pos, void *val,
 249                                 size_t bytes)
 250 {
 251         struct rtc_plat_data *pdata = priv;
 252         void __iomem *ioaddr = pdata->ioaddr;
 253         u8 *buf = val;
 254
 255         for (; bytes; bytes--)
 256                 writeb(*buf++, ioaddr + pos++);
 257         return 0;
 258 }
 259
 260 static int stk17ta8_rtc_probe(struct platform_device *pdev)
 261 {
 262         struct resource *res;
 263         unsigned int cal;
 264         unsigned int flags;
 265         struct rtc_plat_data *pdata;
 266         void __iomem *ioaddr;
 267         int ret = 0;
 268         struct nvmem_config nvmem_cfg = {
 269                 .name = "stk17ta8_nvram",
 270                 .word_size = 1,
 271                 .stride = 1,
 272                 .size = RTC_OFFSET,
 273                 .reg_read = stk17ta8_nvram_read,
 274                 .reg_write = stk17ta8_nvram_write,
 275         };
 276
 277         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 278         if (!pdata)
 279                 return -ENOMEM;
 280
 281         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 282         ioaddr = devm_ioremap_resource(&pdev->dev, res);
 283         if (IS_ERR(ioaddr))
 284                 return PTR_ERR(ioaddr);
 285         pdata->ioaddr = ioaddr;
 286         pdata->irq = platform_get_irq(pdev, 0);
 287
 288         /* turn RTC on if it was not on */
 289         cal = readb(ioaddr + RTC_CALIBRATION);
 290         if (cal & RTC_STOP) {
 291                 cal &= RTC_CAL_MASK;
 292                 flags = readb(ioaddr + RTC_FLAGS);
 293                 writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
 294                 writeb(cal, ioaddr + RTC_CALIBRATION);
 295                 writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
 296         }
 297         if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
 298                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 299
 300         spin_lock_init(&pdata->lock);
 301         pdata->last_jiffies = jiffies;
 302         platform_set_drvdata(pdev, pdata);
 303         if (pdata->irq > 0) {
 304                 writeb(0, ioaddr + RTC_INTERRUPTS);
 305                 if (devm_request_irq(&pdev->dev, pdata->irq,
 306                                 stk17ta8_rtc_interrupt,
 307                                 IRQF_SHARED,
 308                                 pdev->name, pdev) < 0) {
 309                         dev_warn(&pdev->dev, "interrupt not available.\n");
 310                         pdata->irq = 0;
 311                 }
 312         }
 313
 314         pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
 315         if (IS_ERR(pdata->rtc))
 316                 return PTR_ERR(pdata->rtc);
 317
 318         pdata->rtc->ops = &stk17ta8_rtc_ops;
 319         pdata->rtc->nvram_old_abi = true;
 320
 321         nvmem_cfg.priv = pdata;
 322         ret = rtc_nvmem_register(pdata->rtc, &nvmem_cfg);
 323         if (ret)
 324                 return ret;
 325
 326         return rtc_register_device(pdata->rtc);
 327 }
 328
 329 /* work with hotplug and coldplug */
 330 MODULE_ALIAS("platform:stk17ta8");
 331
 332 static struct platform_driver stk17ta8_rtc_driver = {
 333         .probe          = stk17ta8_rtc_probe,
 334         .driver         = {
 335                 .name   = "stk17ta8",
 336         },
 337 };
 338
 339 module_platform_driver(stk17ta8_rtc_driver);
 340
 341 MODULE_AUTHOR("Thomas Hommel <thomas.hommel@ge.com>");
 342 MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver");
 343 MODULE_LICENSE("GPL");