drivers/rtc/rtc-pic32.c

   1 /*
   2  * PIC32 RTC driver
   3  *
   4  * Joshua Henderson <joshua.henderson@microchip.com>
   5  * Copyright (C) 2016 Microchip Technology Inc.  All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  */
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/io.h>
  22 #include <linux/slab.h>
  23 #include <linux/clk.h>
  24 #include <linux/rtc.h>
  25 #include <linux/bcd.h>
  26
  27 #include <asm/mach-pic32/pic32.h>
  28
  29 #define PIC32_RTCCON            0x00
  30 #define PIC32_RTCCON_ON         BIT(15)
  31 #define PIC32_RTCCON_SIDL       BIT(13)
  32 #define PIC32_RTCCON_RTCCLKSEL  (3 << 9)
  33 #define PIC32_RTCCON_RTCCLKON   BIT(6)
  34 #define PIC32_RTCCON_RTCWREN    BIT(3)
  35 #define PIC32_RTCCON_RTCSYNC    BIT(2)
  36 #define PIC32_RTCCON_HALFSEC    BIT(1)
  37 #define PIC32_RTCCON_RTCOE      BIT(0)
  38
  39 #define PIC32_RTCALRM           0x10
  40 #define PIC32_RTCALRM_ALRMEN    BIT(15)
  41 #define PIC32_RTCALRM_CHIME     BIT(14)
  42 #define PIC32_RTCALRM_PIV       BIT(13)
  43 #define PIC32_RTCALRM_ALARMSYNC BIT(12)
  44 #define PIC32_RTCALRM_AMASK     0x0F00
  45 #define PIC32_RTCALRM_ARPT      0xFF
  46
  47 #define PIC32_RTCHOUR           0x23
  48 #define PIC32_RTCMIN            0x22
  49 #define PIC32_RTCSEC            0x21
  50 #define PIC32_RTCYEAR           0x33
  51 #define PIC32_RTCMON            0x32
  52 #define PIC32_RTCDAY            0x31
  53
  54 #define PIC32_ALRMTIME          0x40
  55 #define PIC32_ALRMDATE          0x50
  56
  57 #define PIC32_ALRMHOUR          0x43
  58 #define PIC32_ALRMMIN           0x42
  59 #define PIC32_ALRMSEC           0x41
  60 #define PIC32_ALRMYEAR          0x53
  61 #define PIC32_ALRMMON           0x52
  62 #define PIC32_ALRMDAY           0x51
  63
  64 struct pic32_rtc_dev {
  65         struct rtc_device       *rtc;
  66         void __iomem            *reg_base;
  67         struct clk              *clk;
  68         spinlock_t              alarm_lock;
  69         int                     alarm_irq;
  70         bool                    alarm_clk_enabled;
  71 };
  72
  73 static void pic32_rtc_alarm_clk_enable(struct pic32_rtc_dev *pdata,
  74                                        bool enable)
  75 {
  76         unsigned long flags;
  77
  78         spin_lock_irqsave(&pdata->alarm_lock, flags);
  79         if (enable) {
  80                 if (!pdata->alarm_clk_enabled) {
  81                         clk_enable(pdata->clk);
  82                         pdata->alarm_clk_enabled = true;
  83                 }
  84         } else {
  85                 if (pdata->alarm_clk_enabled) {
  86                         clk_disable(pdata->clk);
  87                         pdata->alarm_clk_enabled = false;
  88                 }
  89         }
  90         spin_unlock_irqrestore(&pdata->alarm_lock, flags);
  91 }
  92
  93 static irqreturn_t pic32_rtc_alarmirq(int irq, void *id)
  94 {
  95         struct pic32_rtc_dev *pdata = (struct pic32_rtc_dev *)id;
  96
  97         clk_enable(pdata->clk);
  98         rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF);
  99         clk_disable(pdata->clk);
 100
 101         pic32_rtc_alarm_clk_enable(pdata, false);
 102
 103         return IRQ_HANDLED;
 104 }
 105
 106 static int pic32_rtc_setaie(struct device *dev, unsigned int enabled)
 107 {
 108         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 109         void __iomem *base = pdata->reg_base;
 110
 111         clk_enable(pdata->clk);
 112
 113         writel(PIC32_RTCALRM_ALRMEN,
 114                base + (enabled ? PIC32_SET(PIC32_RTCALRM) :
 115                        PIC32_CLR(PIC32_RTCALRM)));
 116
 117         clk_disable(pdata->clk);
 118
 119         pic32_rtc_alarm_clk_enable(pdata, enabled);
 120
 121         return 0;
 122 }
 123
 124 static int pic32_rtc_setfreq(struct device *dev, int freq)
 125 {
 126         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 127         void __iomem *base = pdata->reg_base;
 128
 129         clk_enable(pdata->clk);
 130
 131         writel(PIC32_RTCALRM_AMASK, base + PIC32_CLR(PIC32_RTCALRM));
 132         writel(freq << 8, base + PIC32_SET(PIC32_RTCALRM));
 133         writel(PIC32_RTCALRM_CHIME, base + PIC32_SET(PIC32_RTCALRM));
 134
 135         clk_disable(pdata->clk);
 136
 137         return 0;
 138 }
 139
 140 static int pic32_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
 141 {
 142         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 143         void __iomem *base = pdata->reg_base;
 144         unsigned int tries = 0;
 145
 146         clk_enable(pdata->clk);
 147
 148         do {
 149                 rtc_tm->tm_hour = readb(base + PIC32_RTCHOUR);
 150                 rtc_tm->tm_min = readb(base + PIC32_RTCMIN);
 151                 rtc_tm->tm_mon  = readb(base + PIC32_RTCMON);
 152                 rtc_tm->tm_mday = readb(base + PIC32_RTCDAY);
 153                 rtc_tm->tm_year = readb(base + PIC32_RTCYEAR);
 154                 rtc_tm->tm_sec  = readb(base + PIC32_RTCSEC);
 155
 156                 /*
 157                  * The only way to work out whether the system was mid-update
 158                  * when we read it is to check the second counter, and if it
 159                  * is zero, then we re-try the entire read.
 160                  */
 161                 tries += 1;
 162         } while (rtc_tm->tm_sec == 0 && tries < 2);
 163
 164         rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
 165         rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
 166         rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
 167         rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
 168         rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon) - 1;
 169         rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
 170
 171         rtc_tm->tm_year += 100;
 172
 173         dev_dbg(dev, "read time %04d.%02d.%02d %02d:%02d:%02d\n",
 174                 1900 + rtc_tm->tm_year, rtc_tm->tm_mon, rtc_tm->tm_mday,
 175                 rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);
 176
 177         clk_disable(pdata->clk);
 178         return rtc_valid_tm(rtc_tm);
 179 }
 180
 181 static int pic32_rtc_settime(struct device *dev, struct rtc_time *tm)
 182 {
 183         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 184         void __iomem *base = pdata->reg_base;
 185         int year = tm->tm_year - 100;
 186
 187         dev_dbg(dev, "set time %04d.%02d.%02d %02d:%02d:%02d\n",
 188                 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
 189                 tm->tm_hour, tm->tm_min, tm->tm_sec);
 190
 191         if (year < 0 || year >= 100) {
 192                 dev_err(dev, "rtc only supports 100 years\n");
 193                 return -EINVAL;
 194         }
 195
 196         clk_enable(pdata->clk);
 197         writeb(bin2bcd(tm->tm_sec),  base + PIC32_RTCSEC);
 198         writeb(bin2bcd(tm->tm_min),  base + PIC32_RTCMIN);
 199         writeb(bin2bcd(tm->tm_hour), base + PIC32_RTCHOUR);
 200         writeb(bin2bcd(tm->tm_mday), base + PIC32_RTCDAY);
 201         writeb(bin2bcd(tm->tm_mon + 1), base + PIC32_RTCMON);
 202         writeb(bin2bcd(year), base + PIC32_RTCYEAR);
 203         clk_disable(pdata->clk);
 204
 205         return 0;
 206 }
 207
 208 static int pic32_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
 209 {
 210         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 211         struct rtc_time *alm_tm = &alrm->time;
 212         void __iomem *base = pdata->reg_base;
 213         unsigned int alm_en;
 214
 215         clk_enable(pdata->clk);
 216         alm_tm->tm_sec  = readb(base + PIC32_ALRMSEC);
 217         alm_tm->tm_min  = readb(base + PIC32_ALRMMIN);
 218         alm_tm->tm_hour = readb(base + PIC32_ALRMHOUR);
 219         alm_tm->tm_mon  = readb(base + PIC32_ALRMMON);
 220         alm_tm->tm_mday = readb(base + PIC32_ALRMDAY);
 221         alm_tm->tm_year = readb(base + PIC32_ALRMYEAR);
 222
 223         alm_en = readb(base + PIC32_RTCALRM);
 224
 225         alrm->enabled = (alm_en & PIC32_RTCALRM_ALRMEN) ? 1 : 0;
 226
 227         dev_dbg(dev, "getalarm: %d, %04d.%02d.%02d %02d:%02d:%02d\n",
 228                 alm_en,
 229                 1900 + alm_tm->tm_year, alm_tm->tm_mon, alm_tm->tm_mday,
 230                 alm_tm->tm_hour, alm_tm->tm_min, alm_tm->tm_sec);
 231
 232         alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);
 233         alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
 234         alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
 235         alm_tm->tm_mday = bcd2bin(alm_tm->tm_mday);
 236         alm_tm->tm_mon = bcd2bin(alm_tm->tm_mon) - 1;
 237         alm_tm->tm_year = bcd2bin(alm_tm->tm_year);
 238
 239         clk_disable(pdata->clk);
 240         return 0;
 241 }
 242
 243 static int pic32_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 244 {
 245         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 246         struct rtc_time *tm = &alrm->time;
 247         void __iomem *base = pdata->reg_base;
 248
 249         clk_enable(pdata->clk);
 250         dev_dbg(dev, "setalarm: %d, %04d.%02d.%02d %02d:%02d:%02d\n",
 251                 alrm->enabled,
 252                 1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
 253                 tm->tm_hour, tm->tm_min, tm->tm_sec);
 254
 255         writel(0x00, base + PIC32_ALRMTIME);
 256         writel(0x00, base + PIC32_ALRMDATE);
 257
 258         pic32_rtc_setaie(dev, alrm->enabled);
 259
 260         clk_disable(pdata->clk);
 261         return 0;
 262 }
 263
 264 static int pic32_rtc_proc(struct device *dev, struct seq_file *seq)
 265 {
 266         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 267         void __iomem *base = pdata->reg_base;
 268         unsigned int repeat;
 269
 270         clk_enable(pdata->clk);
 271
 272         repeat = readw(base + PIC32_RTCALRM);
 273         repeat &= PIC32_RTCALRM_ARPT;
 274         seq_printf(seq, "periodic_IRQ\t: %s\n", repeat  ? "yes" : "no");
 275
 276         clk_disable(pdata->clk);
 277         return 0;
 278 }
 279
 280 static const struct rtc_class_ops pic32_rtcops = {
 281         .read_time        = pic32_rtc_gettime,
 282         .set_time         = pic32_rtc_settime,
 283         .read_alarm       = pic32_rtc_getalarm,
 284         .set_alarm        = pic32_rtc_setalarm,
 285         .proc             = pic32_rtc_proc,
 286         .alarm_irq_enable = pic32_rtc_setaie,
 287 };
 288
 289 static void pic32_rtc_enable(struct pic32_rtc_dev *pdata, int en)
 290 {
 291         void __iomem *base = pdata->reg_base;
 292
 293         if (!base)
 294                 return;
 295
 296         clk_enable(pdata->clk);
 297         if (!en) {
 298                 writel(PIC32_RTCCON_ON, base + PIC32_CLR(PIC32_RTCCON));
 299         } else {
 300                 pic32_syskey_unlock();
 301
 302                 writel(PIC32_RTCCON_RTCWREN, base + PIC32_SET(PIC32_RTCCON));
 303                 writel(3 << 9, base + PIC32_CLR(PIC32_RTCCON));
 304
 305                 if (!(readl(base + PIC32_RTCCON) & PIC32_RTCCON_ON))
 306                         writel(PIC32_RTCCON_ON, base + PIC32_SET(PIC32_RTCCON));
 307         }
 308         clk_disable(pdata->clk);
 309 }
 310
 311 static int pic32_rtc_remove(struct platform_device *pdev)
 312 {
 313         struct pic32_rtc_dev *pdata = platform_get_drvdata(pdev);
 314
 315         pic32_rtc_setaie(&pdev->dev, 0);
 316         clk_unprepare(pdata->clk);
 317         pdata->clk = NULL;
 318
 319         return 0;
 320 }
 321
 322 static int pic32_rtc_probe(struct platform_device *pdev)
 323 {
 324         struct pic32_rtc_dev *pdata;
 325         struct resource *res;
 326         int ret;
 327
 328         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 329         if (!pdata)
 330                 return -ENOMEM;
 331
 332         platform_set_drvdata(pdev, pdata);
 333
 334         pdata->alarm_irq = platform_get_irq(pdev, 0);
 335         if (pdata->alarm_irq < 0) {
 336                 dev_err(&pdev->dev, "no irq for alarm\n");
 337                 return pdata->alarm_irq;
 338         }
 339
 340         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 341         pdata->reg_base = devm_ioremap_resource(&pdev->dev, res);
 342         if (IS_ERR(pdata->reg_base))
 343                 return PTR_ERR(pdata->reg_base);
 344
 345         pdata->clk = devm_clk_get(&pdev->dev, NULL);
 346         if (IS_ERR(pdata->clk)) {
 347                 dev_err(&pdev->dev, "failed to find rtc clock source\n");
 348                 ret = PTR_ERR(pdata->clk);
 349                 pdata->clk = NULL;
 350                 return ret;
 351         }
 352
 353         spin_lock_init(&pdata->alarm_lock);
 354
 355         clk_prepare_enable(pdata->clk);
 356
 357         pic32_rtc_enable(pdata, 1);
 358
 359         device_init_wakeup(&pdev->dev, 1);
 360
 361         pdata->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 362                                                  &pic32_rtcops,
 363                                                  THIS_MODULE);
 364         if (IS_ERR(pdata->rtc)) {
 365                 ret = PTR_ERR(pdata->rtc);
 366                 goto err_nortc;
 367         }
 368
 369         pdata->rtc->max_user_freq = 128;
 370
 371         pic32_rtc_setfreq(&pdev->dev, 1);
 372         ret = devm_request_irq(&pdev->dev, pdata->alarm_irq,
 373                                pic32_rtc_alarmirq, 0,
 374                                dev_name(&pdev->dev), pdata);
 375         if (ret) {
 376                 dev_err(&pdev->dev,
 377                         "IRQ %d error %d\n", pdata->alarm_irq, ret);
 378                 goto err_nortc;
 379         }
 380
 381         clk_disable(pdata->clk);
 382
 383         return 0;
 384
 385 err_nortc:
 386         pic32_rtc_enable(pdata, 0);
 387         clk_disable_unprepare(pdata->clk);
 388
 389         return ret;
 390 }
 391
 392 static const struct of_device_id pic32_rtc_dt_ids[] = {
 393         { .compatible = "microchip,pic32mzda-rtc" },
 394         { /* sentinel */ }
 395 };
 396 MODULE_DEVICE_TABLE(of, pic32_rtc_dt_ids);
 397
 398 static struct platform_driver pic32_rtc_driver = {
 399         .probe          = pic32_rtc_probe,
 400         .remove         = pic32_rtc_remove,
 401         .driver         = {
 402                 .name   = "pic32-rtc",
 403                 .of_match_table = of_match_ptr(pic32_rtc_dt_ids),
 404         },
 405 };
 406 module_platform_driver(pic32_rtc_driver);
 407
 408 MODULE_DESCRIPTION("Microchip PIC32 RTC Driver");
 409 MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
 410 MODULE_LICENSE("GPL");