drivers/rtc/rtc-stk17ta8.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * A RTC driver for the Simtek STK17TA8
   4  *
   5  * By Thomas Hommel <thomas.hommel@ge.com>
   6  *
   7  * Based on the DS1553 driver from
   8  * Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   9  */
  10
  11 #include <linux/bcd.h>
  12 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/gfp.h>
  15 #include <linux/delay.h>
  16 #include <linux/jiffies.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/rtc.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/io.h>
  21 #include <linux/module.h>
  22
  23 #define RTC_REG_SIZE            0x20000
  24 #define RTC_OFFSET              0x1fff0
  25
  26 #define RTC_FLAGS               (RTC_OFFSET + 0)
  27 #define RTC_CENTURY             (RTC_OFFSET + 1)
  28 #define RTC_SECONDS_ALARM       (RTC_OFFSET + 2)
  29 #define RTC_MINUTES_ALARM       (RTC_OFFSET + 3)
  30 #define RTC_HOURS_ALARM         (RTC_OFFSET + 4)
  31 #define RTC_DATE_ALARM          (RTC_OFFSET + 5)
  32 #define RTC_INTERRUPTS          (RTC_OFFSET + 6)
  33 #define RTC_WATCHDOG            (RTC_OFFSET + 7)
  34 #define RTC_CALIBRATION         (RTC_OFFSET + 8)
  35 #define RTC_SECONDS             (RTC_OFFSET + 9)
  36 #define RTC_MINUTES             (RTC_OFFSET + 10)
  37 #define RTC_HOURS               (RTC_OFFSET + 11)
  38 #define RTC_DAY                 (RTC_OFFSET + 12)
  39 #define RTC_DATE                (RTC_OFFSET + 13)
  40 #define RTC_MONTH               (RTC_OFFSET + 14)
  41 #define RTC_YEAR                (RTC_OFFSET + 15)
  42
  43 #define RTC_SECONDS_MASK        0x7f
  44 #define RTC_DAY_MASK            0x07
  45 #define RTC_CAL_MASK            0x3f
  46
  47 /* Bits in the Calibration register */
  48 #define RTC_STOP                0x80
  49
  50 /* Bits in the Flags register */
  51 #define RTC_FLAGS_AF            0x40
  52 #define RTC_FLAGS_PF            0x20
  53 #define RTC_WRITE               0x02
  54 #define RTC_READ                0x01
  55
  56 /* Bits in the Interrupts register */
  57 #define RTC_INTS_AIE            0x40
  58
  59 struct rtc_plat_data {
  60         struct rtc_device *rtc;
  61         void __iomem *ioaddr;
  62         unsigned long last_jiffies;
  63         int irq;
  64         unsigned int irqen;
  65         int alrm_sec;
  66         int alrm_min;
  67         int alrm_hour;
  68         int alrm_mday;
  69         spinlock_t lock;
  70 };
  71
  72 static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
  73 {
  74         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
  75         void __iomem *ioaddr = pdata->ioaddr;
  76         u8 flags;
  77
  78         flags = readb(pdata->ioaddr + RTC_FLAGS);
  79         writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
  80
  81         writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
  82         writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
  83         writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
  84         writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
  85         writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
  86         writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
  87         writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
  88         writeb(bin2bcd((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY);
  89
  90         writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
  91         return 0;
  92 }
  93
  94 static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm)
  95 {
  96         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
  97         void __iomem *ioaddr = pdata->ioaddr;
  98         unsigned int year, month, day, hour, minute, second, week;
  99         unsigned int century;
 100         u8 flags;
 101
 102         /* give enough time to update RTC in case of continuous read */
 103         if (pdata->last_jiffies == jiffies)
 104                 msleep(1);
 105         pdata->last_jiffies = jiffies;
 106
 107         flags = readb(pdata->ioaddr + RTC_FLAGS);
 108         writeb(flags | RTC_READ, ioaddr + RTC_FLAGS);
 109         second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
 110         minute = readb(ioaddr + RTC_MINUTES);
 111         hour = readb(ioaddr + RTC_HOURS);
 112         day = readb(ioaddr + RTC_DATE);
 113         week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
 114         month = readb(ioaddr + RTC_MONTH);
 115         year = readb(ioaddr + RTC_YEAR);
 116         century = readb(ioaddr + RTC_CENTURY);
 117         writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS);
 118         tm->tm_sec = bcd2bin(second);
 119         tm->tm_min = bcd2bin(minute);
 120         tm->tm_hour = bcd2bin(hour);
 121         tm->tm_mday = bcd2bin(day);
 122         tm->tm_wday = bcd2bin(week);
 123         tm->tm_mon = bcd2bin(month) - 1;
 124         /* year is 1900 + tm->tm_year */
 125         tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
 126
 127         return 0;
 128 }
 129
 130 static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
 131 {
 132         void __iomem *ioaddr = pdata->ioaddr;
 133         unsigned long irqflags;
 134         u8 flags;
 135
 136         spin_lock_irqsave(&pdata->lock, irqflags);
 137
 138         flags = readb(ioaddr + RTC_FLAGS);
 139         writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
 140
 141         writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
 142                0x80 : bin2bcd(pdata->alrm_mday),
 143                ioaddr + RTC_DATE_ALARM);
 144         writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
 145                0x80 : bin2bcd(pdata->alrm_hour),
 146                ioaddr + RTC_HOURS_ALARM);
 147         writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
 148                0x80 : bin2bcd(pdata->alrm_min),
 149                ioaddr + RTC_MINUTES_ALARM);
 150         writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
 151                0x80 : bin2bcd(pdata->alrm_sec),
 152                ioaddr + RTC_SECONDS_ALARM);
 153         writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS);
 154         readb(ioaddr + RTC_FLAGS);      /* clear interrupts */
 155         writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
 156         spin_unlock_irqrestore(&pdata->lock, irqflags);
 157 }
 158
 159 static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 160 {
 161         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 162
 163         if (pdata->irq <= 0)
 164                 return -EINVAL;
 165         pdata->alrm_mday = alrm->time.tm_mday;
 166         pdata->alrm_hour = alrm->time.tm_hour;
 167         pdata->alrm_min = alrm->time.tm_min;
 168         pdata->alrm_sec = alrm->time.tm_sec;
 169         if (alrm->enabled)
 170                 pdata->irqen |= RTC_AF;
 171         stk17ta8_rtc_update_alarm(pdata);
 172         return 0;
 173 }
 174
 175 static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 176 {
 177         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 178
 179         if (pdata->irq <= 0)
 180                 return -EINVAL;
 181         alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
 182         alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
 183         alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
 184         alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
 185         alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
 186         return 0;
 187 }
 188
 189 static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id)
 190 {
 191         struct platform_device *pdev = dev_id;
 192         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 193         void __iomem *ioaddr = pdata->ioaddr;
 194         unsigned long events = 0;
 195
 196         spin_lock(&pdata->lock);
 197         /* read and clear interrupt */
 198         if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
 199                 events = RTC_IRQF;
 200                 if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
 201                         events |= RTC_UF;
 202                 else
 203                         events |= RTC_AF;
 204                 rtc_update_irq(pdata->rtc, 1, events);
 205         }
 206         spin_unlock(&pdata->lock);
 207         return events ? IRQ_HANDLED : IRQ_NONE;
 208 }
 209
 210 static int stk17ta8_rtc_alarm_irq_enable(struct device *dev,
 211         unsigned int enabled)
 212 {
 213         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 214
 215         if (pdata->irq <= 0)
 216                 return -EINVAL;
 217         if (enabled)
 218                 pdata->irqen |= RTC_AF;
 219         else
 220                 pdata->irqen &= ~RTC_AF;
 221         stk17ta8_rtc_update_alarm(pdata);
 222         return 0;
 223 }
 224
 225 static const struct rtc_class_ops stk17ta8_rtc_ops = {
 226         .read_time              = stk17ta8_rtc_read_time,
 227         .set_time               = stk17ta8_rtc_set_time,
 228         .read_alarm             = stk17ta8_rtc_read_alarm,
 229         .set_alarm              = stk17ta8_rtc_set_alarm,
 230         .alarm_irq_enable       = stk17ta8_rtc_alarm_irq_enable,
 231 };
 232
 233 static int stk17ta8_nvram_read(void *priv, unsigned int pos, void *val,
 234                                size_t bytes)
 235 {
 236         struct rtc_plat_data *pdata = priv;
 237         void __iomem *ioaddr = pdata->ioaddr;
 238         u8 *buf = val;
 239
 240         for (; bytes; bytes--)
 241                 *buf++ = readb(ioaddr + pos++);
 242         return 0;
 243 }
 244
 245 static int stk17ta8_nvram_write(void *priv, unsigned int pos, void *val,
 246                                 size_t bytes)
 247 {
 248         struct rtc_plat_data *pdata = priv;
 249         void __iomem *ioaddr = pdata->ioaddr;
 250         u8 *buf = val;
 251
 252         for (; bytes; bytes--)
 253                 writeb(*buf++, ioaddr + pos++);
 254         return 0;
 255 }
 256
 257 static int stk17ta8_rtc_probe(struct platform_device *pdev)
 258 {
 259         unsigned int cal;
 260         unsigned int flags;
 261         struct rtc_plat_data *pdata;
 262         void __iomem *ioaddr;
 263         int ret = 0;
 264         struct nvmem_config nvmem_cfg = {
 265                 .name = "stk17ta8_nvram",
 266                 .word_size = 1,
 267                 .stride = 1,
 268                 .size = RTC_OFFSET,
 269                 .reg_read = stk17ta8_nvram_read,
 270                 .reg_write = stk17ta8_nvram_write,
 271         };
 272
 273         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 274         if (!pdata)
 275                 return -ENOMEM;
 276
 277         ioaddr = devm_platform_ioremap_resource(pdev, 0);
 278         if (IS_ERR(ioaddr))
 279                 return PTR_ERR(ioaddr);
 280         pdata->ioaddr = ioaddr;
 281         pdata->irq = platform_get_irq(pdev, 0);
 282
 283         /* turn RTC on if it was not on */
 284         cal = readb(ioaddr + RTC_CALIBRATION);
 285         if (cal & RTC_STOP) {
 286                 cal &= RTC_CAL_MASK;
 287                 flags = readb(ioaddr + RTC_FLAGS);
 288                 writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
 289                 writeb(cal, ioaddr + RTC_CALIBRATION);
 290                 writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
 291         }
 292         if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
 293                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 294
 295         spin_lock_init(&pdata->lock);
 296         pdata->last_jiffies = jiffies;
 297         platform_set_drvdata(pdev, pdata);
 298         if (pdata->irq > 0) {
 299                 writeb(0, ioaddr + RTC_INTERRUPTS);
 300                 if (devm_request_irq(&pdev->dev, pdata->irq,
 301                                 stk17ta8_rtc_interrupt,
 302                                 IRQF_SHARED,
 303                                 pdev->name, pdev) < 0) {
 304                         dev_warn(&pdev->dev, "interrupt not available.\n");
 305                         pdata->irq = 0;
 306                 }
 307         }
 308
 309         pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
 310         if (IS_ERR(pdata->rtc))
 311                 return PTR_ERR(pdata->rtc);
 312
 313         pdata->rtc->ops = &stk17ta8_rtc_ops;
 314
 315         nvmem_cfg.priv = pdata;
 316         ret = devm_rtc_nvmem_register(pdata->rtc, &nvmem_cfg);
 317         if (ret)
 318                 return ret;
 319
 320         return devm_rtc_register_device(pdata->rtc);
 321 }
 322
 323 /* work with hotplug and coldplug */
 324 MODULE_ALIAS("platform:stk17ta8");
 325
 326 static struct platform_driver stk17ta8_rtc_driver = {
 327         .probe          = stk17ta8_rtc_probe,
 328         .driver         = {
 329                 .name   = "stk17ta8",
 330         },
 331 };
 332
 333 module_platform_driver(stk17ta8_rtc_driver);
 334
 335 MODULE_AUTHOR("Thomas Hommel <thomas.hommel@ge.com>");
 336 MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver");
 337 MODULE_LICENSE("GPL");