drivers/rtc/rtc-pic32.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * PIC32 RTC driver
   4  *
   5  * Joshua Henderson <joshua.henderson@microchip.com>
   6  * Copyright (C) 2016 Microchip Technology Inc.  All rights reserved.
   7  *
   8  */
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/io.h>
  14 #include <linux/slab.h>
  15 #include <linux/clk.h>
  16 #include <linux/rtc.h>
  17 #include <linux/bcd.h>
  18
  19 #include <asm/mach-pic32/pic32.h>
  20
  21 #define PIC32_RTCCON            0x00
  22 #define PIC32_RTCCON_ON         BIT(15)
  23 #define PIC32_RTCCON_SIDL       BIT(13)
  24 #define PIC32_RTCCON_RTCCLKSEL  (3 << 9)
  25 #define PIC32_RTCCON_RTCCLKON   BIT(6)
  26 #define PIC32_RTCCON_RTCWREN    BIT(3)
  27 #define PIC32_RTCCON_RTCSYNC    BIT(2)
  28 #define PIC32_RTCCON_HALFSEC    BIT(1)
  29 #define PIC32_RTCCON_RTCOE      BIT(0)
  30
  31 #define PIC32_RTCALRM           0x10
  32 #define PIC32_RTCALRM_ALRMEN    BIT(15)
  33 #define PIC32_RTCALRM_CHIME     BIT(14)
  34 #define PIC32_RTCALRM_PIV       BIT(13)
  35 #define PIC32_RTCALRM_ALARMSYNC BIT(12)
  36 #define PIC32_RTCALRM_AMASK     0x0F00
  37 #define PIC32_RTCALRM_ARPT      0xFF
  38
  39 #define PIC32_RTCHOUR           0x23
  40 #define PIC32_RTCMIN            0x22
  41 #define PIC32_RTCSEC            0x21
  42 #define PIC32_RTCYEAR           0x33
  43 #define PIC32_RTCMON            0x32
  44 #define PIC32_RTCDAY            0x31
  45
  46 #define PIC32_ALRMTIME          0x40
  47 #define PIC32_ALRMDATE          0x50
  48
  49 #define PIC32_ALRMHOUR          0x43
  50 #define PIC32_ALRMMIN           0x42
  51 #define PIC32_ALRMSEC           0x41
  52 #define PIC32_ALRMYEAR          0x53
  53 #define PIC32_ALRMMON           0x52
  54 #define PIC32_ALRMDAY           0x51
  55
  56 struct pic32_rtc_dev {
  57         struct rtc_device       *rtc;
  58         void __iomem            *reg_base;
  59         struct clk              *clk;
  60         spinlock_t              alarm_lock;
  61         int                     alarm_irq;
  62         bool                    alarm_clk_enabled;
  63 };
  64
  65 static void pic32_rtc_alarm_clk_enable(struct pic32_rtc_dev *pdata,
  66                                        bool enable)
  67 {
  68         unsigned long flags;
  69
  70         spin_lock_irqsave(&pdata->alarm_lock, flags);
  71         if (enable) {
  72                 if (!pdata->alarm_clk_enabled) {
  73                         clk_enable(pdata->clk);
  74                         pdata->alarm_clk_enabled = true;
  75                 }
  76         } else {
  77                 if (pdata->alarm_clk_enabled) {
  78                         clk_disable(pdata->clk);
  79                         pdata->alarm_clk_enabled = false;
  80                 }
  81         }
  82         spin_unlock_irqrestore(&pdata->alarm_lock, flags);
  83 }
  84
  85 static irqreturn_t pic32_rtc_alarmirq(int irq, void *id)
  86 {
  87         struct pic32_rtc_dev *pdata = (struct pic32_rtc_dev *)id;
  88
  89         clk_enable(pdata->clk);
  90         rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF);
  91         clk_disable(pdata->clk);
  92
  93         pic32_rtc_alarm_clk_enable(pdata, false);
  94
  95         return IRQ_HANDLED;
  96 }
  97
  98 static int pic32_rtc_setaie(struct device *dev, unsigned int enabled)
  99 {
 100         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 101         void __iomem *base = pdata->reg_base;
 102
 103         clk_enable(pdata->clk);
 104
 105         writel(PIC32_RTCALRM_ALRMEN,
 106                base + (enabled ? PIC32_SET(PIC32_RTCALRM) :
 107                        PIC32_CLR(PIC32_RTCALRM)));
 108
 109         clk_disable(pdata->clk);
 110
 111         pic32_rtc_alarm_clk_enable(pdata, enabled);
 112
 113         return 0;
 114 }
 115
 116 static int pic32_rtc_setfreq(struct device *dev, int freq)
 117 {
 118         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 119         void __iomem *base = pdata->reg_base;
 120
 121         clk_enable(pdata->clk);
 122
 123         writel(PIC32_RTCALRM_AMASK, base + PIC32_CLR(PIC32_RTCALRM));
 124         writel(freq << 8, base + PIC32_SET(PIC32_RTCALRM));
 125         writel(PIC32_RTCALRM_CHIME, base + PIC32_SET(PIC32_RTCALRM));
 126
 127         clk_disable(pdata->clk);
 128
 129         return 0;
 130 }
 131
 132 static int pic32_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
 133 {
 134         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 135         void __iomem *base = pdata->reg_base;
 136         unsigned int tries = 0;
 137
 138         clk_enable(pdata->clk);
 139
 140         do {
 141                 rtc_tm->tm_hour = readb(base + PIC32_RTCHOUR);
 142                 rtc_tm->tm_min = readb(base + PIC32_RTCMIN);
 143                 rtc_tm->tm_mon  = readb(base + PIC32_RTCMON);
 144                 rtc_tm->tm_mday = readb(base + PIC32_RTCDAY);
 145                 rtc_tm->tm_year = readb(base + PIC32_RTCYEAR);
 146                 rtc_tm->tm_sec  = readb(base + PIC32_RTCSEC);
 147
 148                 /*
 149                  * The only way to work out whether the system was mid-update
 150                  * when we read it is to check the second counter, and if it
 151                  * is zero, then we re-try the entire read.
 152                  */
 153                 tries += 1;
 154         } while (rtc_tm->tm_sec == 0 && tries < 2);
 155
 156         rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
 157         rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
 158         rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
 159         rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
 160         rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon) - 1;
 161         rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
 162
 163         rtc_tm->tm_year += 100;
 164
 165         dev_dbg(dev, "read time %ptR\n", rtc_tm);
 166
 167         clk_disable(pdata->clk);
 168         return 0;
 169 }
 170
 171 static int pic32_rtc_settime(struct device *dev, struct rtc_time *tm)
 172 {
 173         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 174         void __iomem *base = pdata->reg_base;
 175
 176         dev_dbg(dev, "set time %ptR\n", tm);
 177
 178         clk_enable(pdata->clk);
 179         writeb(bin2bcd(tm->tm_sec),  base + PIC32_RTCSEC);
 180         writeb(bin2bcd(tm->tm_min),  base + PIC32_RTCMIN);
 181         writeb(bin2bcd(tm->tm_hour), base + PIC32_RTCHOUR);
 182         writeb(bin2bcd(tm->tm_mday), base + PIC32_RTCDAY);
 183         writeb(bin2bcd(tm->tm_mon + 1), base + PIC32_RTCMON);
 184         writeb(bin2bcd(tm->tm_year - 100), base + PIC32_RTCYEAR);
 185         clk_disable(pdata->clk);
 186
 187         return 0;
 188 }
 189
 190 static int pic32_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
 191 {
 192         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 193         struct rtc_time *alm_tm = &alrm->time;
 194         void __iomem *base = pdata->reg_base;
 195         unsigned int alm_en;
 196
 197         clk_enable(pdata->clk);
 198         alm_tm->tm_sec  = readb(base + PIC32_ALRMSEC);
 199         alm_tm->tm_min  = readb(base + PIC32_ALRMMIN);
 200         alm_tm->tm_hour = readb(base + PIC32_ALRMHOUR);
 201         alm_tm->tm_mon  = readb(base + PIC32_ALRMMON);
 202         alm_tm->tm_mday = readb(base + PIC32_ALRMDAY);
 203         alm_tm->tm_year = readb(base + PIC32_ALRMYEAR);
 204
 205         alm_en = readb(base + PIC32_RTCALRM);
 206
 207         alrm->enabled = (alm_en & PIC32_RTCALRM_ALRMEN) ? 1 : 0;
 208
 209         dev_dbg(dev, "getalarm: %d, %ptR\n", alm_en, alm_tm);
 210
 211         alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);
 212         alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
 213         alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
 214         alm_tm->tm_mday = bcd2bin(alm_tm->tm_mday);
 215         alm_tm->tm_mon = bcd2bin(alm_tm->tm_mon) - 1;
 216         alm_tm->tm_year = bcd2bin(alm_tm->tm_year);
 217
 218         clk_disable(pdata->clk);
 219         return 0;
 220 }
 221
 222 static int pic32_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 223 {
 224         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 225         struct rtc_time *tm = &alrm->time;
 226         void __iomem *base = pdata->reg_base;
 227
 228         clk_enable(pdata->clk);
 229         dev_dbg(dev, "setalarm: %d, %ptR\n", alrm->enabled, tm);
 230
 231         writel(0x00, base + PIC32_ALRMTIME);
 232         writel(0x00, base + PIC32_ALRMDATE);
 233
 234         pic32_rtc_setaie(dev, alrm->enabled);
 235
 236         clk_disable(pdata->clk);
 237         return 0;
 238 }
 239
 240 static int pic32_rtc_proc(struct device *dev, struct seq_file *seq)
 241 {
 242         struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
 243         void __iomem *base = pdata->reg_base;
 244         unsigned int repeat;
 245
 246         clk_enable(pdata->clk);
 247
 248         repeat = readw(base + PIC32_RTCALRM);
 249         repeat &= PIC32_RTCALRM_ARPT;
 250         seq_printf(seq, "periodic_IRQ\t: %s\n", repeat  ? "yes" : "no");
 251
 252         clk_disable(pdata->clk);
 253         return 0;
 254 }
 255
 256 static const struct rtc_class_ops pic32_rtcops = {
 257         .read_time        = pic32_rtc_gettime,
 258         .set_time         = pic32_rtc_settime,
 259         .read_alarm       = pic32_rtc_getalarm,
 260         .set_alarm        = pic32_rtc_setalarm,
 261         .proc             = pic32_rtc_proc,
 262         .alarm_irq_enable = pic32_rtc_setaie,
 263 };
 264
 265 static void pic32_rtc_enable(struct pic32_rtc_dev *pdata, int en)
 266 {
 267         void __iomem *base = pdata->reg_base;
 268
 269         if (!base)
 270                 return;
 271
 272         clk_enable(pdata->clk);
 273         if (!en) {
 274                 writel(PIC32_RTCCON_ON, base + PIC32_CLR(PIC32_RTCCON));
 275         } else {
 276                 pic32_syskey_unlock();
 277
 278                 writel(PIC32_RTCCON_RTCWREN, base + PIC32_SET(PIC32_RTCCON));
 279                 writel(3 << 9, base + PIC32_CLR(PIC32_RTCCON));
 280
 281                 if (!(readl(base + PIC32_RTCCON) & PIC32_RTCCON_ON))
 282                         writel(PIC32_RTCCON_ON, base + PIC32_SET(PIC32_RTCCON));
 283         }
 284         clk_disable(pdata->clk);
 285 }
 286
 287 static int pic32_rtc_remove(struct platform_device *pdev)
 288 {
 289         struct pic32_rtc_dev *pdata = platform_get_drvdata(pdev);
 290
 291         pic32_rtc_setaie(&pdev->dev, 0);
 292         clk_unprepare(pdata->clk);
 293         pdata->clk = NULL;
 294
 295         return 0;
 296 }
 297
 298 static int pic32_rtc_probe(struct platform_device *pdev)
 299 {
 300         struct pic32_rtc_dev *pdata;
 301         int ret;
 302
 303         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 304         if (!pdata)
 305                 return -ENOMEM;
 306
 307         platform_set_drvdata(pdev, pdata);
 308
 309         pdata->alarm_irq = platform_get_irq(pdev, 0);
 310         if (pdata->alarm_irq < 0)
 311                 return pdata->alarm_irq;
 312
 313         pdata->reg_base = devm_platform_ioremap_resource(pdev, 0);
 314         if (IS_ERR(pdata->reg_base))
 315                 return PTR_ERR(pdata->reg_base);
 316
 317         pdata->clk = devm_clk_get(&pdev->dev, NULL);
 318         if (IS_ERR(pdata->clk)) {
 319                 dev_err(&pdev->dev, "failed to find rtc clock source\n");
 320                 ret = PTR_ERR(pdata->clk);
 321                 pdata->clk = NULL;
 322                 return ret;
 323         }
 324
 325         spin_lock_init(&pdata->alarm_lock);
 326
 327         pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
 328         if (IS_ERR(pdata->rtc))
 329                 return PTR_ERR(pdata->rtc);
 330
 331         clk_prepare_enable(pdata->clk);
 332
 333         pic32_rtc_enable(pdata, 1);
 334
 335         device_init_wakeup(&pdev->dev, 1);
 336
 337         pdata->rtc->ops = &pic32_rtcops;
 338         pdata->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 339         pdata->rtc->range_max = RTC_TIMESTAMP_END_2099;
 340
 341         ret = devm_rtc_register_device(pdata->rtc);
 342         if (ret)
 343                 goto err_nortc;
 344
 345         pdata->rtc->max_user_freq = 128;
 346
 347         pic32_rtc_setfreq(&pdev->dev, 1);
 348         ret = devm_request_irq(&pdev->dev, pdata->alarm_irq,
 349                                pic32_rtc_alarmirq, 0,
 350                                dev_name(&pdev->dev), pdata);
 351         if (ret) {
 352                 dev_err(&pdev->dev,
 353                         "IRQ %d error %d\n", pdata->alarm_irq, ret);
 354                 goto err_nortc;
 355         }
 356
 357         clk_disable(pdata->clk);
 358
 359         return 0;
 360
 361 err_nortc:
 362         pic32_rtc_enable(pdata, 0);
 363         clk_disable_unprepare(pdata->clk);
 364
 365         return ret;
 366 }
 367
 368 static const struct of_device_id pic32_rtc_dt_ids[] = {
 369         { .compatible = "microchip,pic32mzda-rtc" },
 370         { /* sentinel */ }
 371 };
 372 MODULE_DEVICE_TABLE(of, pic32_rtc_dt_ids);
 373
 374 static struct platform_driver pic32_rtc_driver = {
 375         .probe          = pic32_rtc_probe,
 376         .remove         = pic32_rtc_remove,
 377         .driver         = {
 378                 .name   = "pic32-rtc",
 379                 .of_match_table = of_match_ptr(pic32_rtc_dt_ids),
 380         },
 381 };
 382 module_platform_driver(pic32_rtc_driver);
 383
 384 MODULE_DESCRIPTION("Microchip PIC32 RTC Driver");
 385 MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
 386 MODULE_LICENSE("GPL");