drivers/rtc/rtc-cpcap.c

   1 /*
   2  * Motorola CPCAP PMIC RTC driver
   3  *
   4  * Based on cpcap-regulator.c from Motorola Linux kernel tree
   5  * Copyright (C) 2009 Motorola, Inc.
   6  *
   7  * Rewritten for mainline kernel
   8  *  - use DT
   9  *  - use regmap
  10  *  - use standard interrupt framework
  11  *  - use managed device resources
  12  *  - remove custom "secure clock daemon" helpers
  13  *
  14  * Copyright (C) 2017 Sebastian Reichel <sre@kernel.org>
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License version 2 as
  18  * published by the Free Software Foundation.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  */
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/init.h>
  28 #include <linux/device.h>
  29 #include <linux/platform_device.h>
  30 #include <linux/rtc.h>
  31 #include <linux/err.h>
  32 #include <linux/regmap.h>
  33 #include <linux/mfd/motorola-cpcap.h>
  34 #include <linux/slab.h>
  35 #include <linux/sched.h>
  36
  37 #define SECS_PER_DAY 86400
  38 #define DAY_MASK  0x7FFF
  39 #define TOD1_MASK 0x00FF
  40 #define TOD2_MASK 0x01FF
  41
  42 struct cpcap_time {
  43         int day;
  44         int tod1;
  45         int tod2;
  46 };
  47
  48 struct cpcap_rtc {
  49         struct regmap *regmap;
  50         struct rtc_device *rtc_dev;
  51         u16 vendor;
  52         int alarm_irq;
  53         bool alarm_enabled;
  54         int update_irq;
  55         bool update_enabled;
  56 };
  57
  58 static void cpcap2rtc_time(struct rtc_time *rtc, struct cpcap_time *cpcap)
  59 {
  60         unsigned long int tod;
  61         unsigned long int time;
  62
  63         tod = (cpcap->tod1 & TOD1_MASK) | ((cpcap->tod2 & TOD2_MASK) << 8);
  64         time = tod + ((cpcap->day & DAY_MASK) * SECS_PER_DAY);
  65
  66         rtc_time_to_tm(time, rtc);
  67 }
  68
  69 static void rtc2cpcap_time(struct cpcap_time *cpcap, struct rtc_time *rtc)
  70 {
  71         unsigned long time;
  72
  73         rtc_tm_to_time(rtc, &time);
  74
  75         cpcap->day = time / SECS_PER_DAY;
  76         time %= SECS_PER_DAY;
  77         cpcap->tod2 = (time >> 8) & TOD2_MASK;
  78         cpcap->tod1 = time & TOD1_MASK;
  79 }
  80
  81 static int cpcap_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
  82 {
  83         struct cpcap_rtc *rtc = dev_get_drvdata(dev);
  84
  85         if (rtc->alarm_enabled == enabled)
  86                 return 0;
  87
  88         if (enabled)
  89                 enable_irq(rtc->alarm_irq);
  90         else
  91                 disable_irq(rtc->alarm_irq);
  92
  93         rtc->alarm_enabled = !!enabled;
  94
  95         return 0;
  96 }
  97
  98 static int cpcap_rtc_read_time(struct device *dev, struct rtc_time *tm)
  99 {
 100         struct cpcap_rtc *rtc;
 101         struct cpcap_time cpcap_tm;
 102         int temp_tod2;
 103         int ret;
 104
 105         rtc = dev_get_drvdata(dev);
 106
 107         ret = regmap_read(rtc->regmap, CPCAP_REG_TOD2, &temp_tod2);
 108         ret |= regmap_read(rtc->regmap, CPCAP_REG_DAY, &cpcap_tm.day);
 109         ret |= regmap_read(rtc->regmap, CPCAP_REG_TOD1, &cpcap_tm.tod1);
 110         ret |= regmap_read(rtc->regmap, CPCAP_REG_TOD2, &cpcap_tm.tod2);
 111
 112         if (temp_tod2 > cpcap_tm.tod2)
 113                 ret |= regmap_read(rtc->regmap, CPCAP_REG_DAY, &cpcap_tm.day);
 114
 115         if (ret) {
 116                 dev_err(dev, "Failed to read time\n");
 117                 return -EIO;
 118         }
 119
 120         cpcap2rtc_time(tm, &cpcap_tm);
 121
 122         return rtc_valid_tm(tm);
 123 }
 124
 125 static int cpcap_rtc_set_time(struct device *dev, struct rtc_time *tm)
 126 {
 127         struct cpcap_rtc *rtc;
 128         struct cpcap_time cpcap_tm;
 129         int ret = 0;
 130
 131         rtc = dev_get_drvdata(dev);
 132
 133         rtc2cpcap_time(&cpcap_tm, tm);
 134
 135         if (rtc->alarm_enabled)
 136                 disable_irq(rtc->alarm_irq);
 137         if (rtc->update_enabled)
 138                 disable_irq(rtc->update_irq);
 139
 140         if (rtc->vendor == CPCAP_VENDOR_ST) {
 141                 /* The TOD1 and TOD2 registers MUST be written in this order
 142                  * for the change to properly set.
 143                  */
 144                 ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
 145                                           TOD1_MASK, cpcap_tm.tod1);
 146                 ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD2,
 147                                           TOD2_MASK, cpcap_tm.tod2);
 148                 ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_DAY,
 149                                           DAY_MASK, cpcap_tm.day);
 150         } else {
 151                 /* Clearing the upper lower 8 bits of the TOD guarantees that
 152                  * the upper half of TOD (TOD2) will not increment for 0xFF RTC
 153                  * ticks (255 seconds).  During this time we can safely write
 154                  * to DAY, TOD2, then TOD1 (in that order) and expect RTC to be
 155                  * synchronized to the exact time requested upon the final write
 156                  * to TOD1.
 157                  */
 158                 ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
 159                                           TOD1_MASK, 0);
 160                 ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_DAY,
 161                                           DAY_MASK, cpcap_tm.day);
 162                 ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD2,
 163                                           TOD2_MASK, cpcap_tm.tod2);
 164                 ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
 165                                           TOD1_MASK, cpcap_tm.tod1);
 166         }
 167
 168         if (rtc->update_enabled)
 169                 enable_irq(rtc->update_irq);
 170         if (rtc->alarm_enabled)
 171                 enable_irq(rtc->alarm_irq);
 172
 173         return ret;
 174 }
 175
 176 static int cpcap_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 177 {
 178         struct cpcap_rtc *rtc;
 179         struct cpcap_time cpcap_tm;
 180         int ret;
 181
 182         rtc = dev_get_drvdata(dev);
 183
 184         alrm->enabled = rtc->alarm_enabled;
 185
 186         ret = regmap_read(rtc->regmap, CPCAP_REG_DAYA, &cpcap_tm.day);
 187         ret |= regmap_read(rtc->regmap, CPCAP_REG_TODA2, &cpcap_tm.tod2);
 188         ret |= regmap_read(rtc->regmap, CPCAP_REG_TODA1, &cpcap_tm.tod1);
 189
 190         if (ret) {
 191                 dev_err(dev, "Failed to read time\n");
 192                 return -EIO;
 193         }
 194
 195         cpcap2rtc_time(&alrm->time, &cpcap_tm);
 196         return rtc_valid_tm(&alrm->time);
 197 }
 198
 199 static int cpcap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 200 {
 201         struct cpcap_rtc *rtc;
 202         struct cpcap_time cpcap_tm;
 203         int ret;
 204
 205         rtc = dev_get_drvdata(dev);
 206
 207         rtc2cpcap_time(&cpcap_tm, &alrm->time);
 208
 209         if (rtc->alarm_enabled)
 210                 disable_irq(rtc->alarm_irq);
 211
 212         ret = regmap_update_bits(rtc->regmap, CPCAP_REG_DAYA, DAY_MASK,
 213                                  cpcap_tm.day);
 214         ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TODA2, TOD2_MASK,
 215                                   cpcap_tm.tod2);
 216         ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TODA1, TOD1_MASK,
 217                                   cpcap_tm.tod1);
 218
 219         if (!ret) {
 220                 enable_irq(rtc->alarm_irq);
 221                 rtc->alarm_enabled = true;
 222         }
 223
 224         return ret;
 225 }
 226
 227 static const struct rtc_class_ops cpcap_rtc_ops = {
 228         .read_time              = cpcap_rtc_read_time,
 229         .set_time               = cpcap_rtc_set_time,
 230         .read_alarm             = cpcap_rtc_read_alarm,
 231         .set_alarm              = cpcap_rtc_set_alarm,
 232         .alarm_irq_enable       = cpcap_rtc_alarm_irq_enable,
 233 };
 234
 235 static irqreturn_t cpcap_rtc_alarm_irq(int irq, void *data)
 236 {
 237         struct cpcap_rtc *rtc = data;
 238
 239         rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
 240         return IRQ_HANDLED;
 241 }
 242
 243 static irqreturn_t cpcap_rtc_update_irq(int irq, void *data)
 244 {
 245         struct cpcap_rtc *rtc = data;
 246
 247         rtc_update_irq(rtc->rtc_dev, 1, RTC_UF | RTC_IRQF);
 248         return IRQ_HANDLED;
 249 }
 250
 251 static int cpcap_rtc_probe(struct platform_device *pdev)
 252 {
 253         struct device *dev = &pdev->dev;
 254         struct cpcap_rtc *rtc;
 255         int err;
 256
 257         rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
 258         if (!rtc)
 259                 return -ENOMEM;
 260
 261         rtc->regmap = dev_get_regmap(dev->parent, NULL);
 262         if (!rtc->regmap)
 263                 return -ENODEV;
 264
 265         platform_set_drvdata(pdev, rtc);
 266         rtc->rtc_dev = devm_rtc_device_register(dev, "cpcap_rtc",
 267                                                 &cpcap_rtc_ops, THIS_MODULE);
 268
 269         if (IS_ERR(rtc->rtc_dev))
 270                 return PTR_ERR(rtc->rtc_dev);
 271
 272         err = cpcap_get_vendor(dev, rtc->regmap, &rtc->vendor);
 273         if (err)
 274                 return err;
 275
 276         rtc->alarm_irq = platform_get_irq(pdev, 0);
 277         err = devm_request_threaded_irq(dev, rtc->alarm_irq, NULL,
 278                                         cpcap_rtc_alarm_irq, IRQF_TRIGGER_NONE,
 279                                         "rtc_alarm", rtc);
 280         if (err) {
 281                 dev_err(dev, "Could not request alarm irq: %d\n", err);
 282                 return err;
 283         }
 284         disable_irq(rtc->alarm_irq);
 285
 286         /* Stock Android uses the 1 Hz interrupt for "secure clock daemon",
 287          * which is not supported by the mainline kernel. The mainline kernel
 288          * does not use the irq at the moment, but we explicitly request and
 289          * disable it, so that its masked and does not wake up the processor
 290          * every second.
 291          */
 292         rtc->update_irq = platform_get_irq(pdev, 1);
 293         err = devm_request_threaded_irq(dev, rtc->update_irq, NULL,
 294                                         cpcap_rtc_update_irq, IRQF_TRIGGER_NONE,
 295                                         "rtc_1hz", rtc);
 296         if (err) {
 297                 dev_err(dev, "Could not request update irq: %d\n", err);
 298                 return err;
 299         }
 300         disable_irq(rtc->update_irq);
 301
 302         err = device_init_wakeup(dev, 1);
 303         if (err) {
 304                 dev_err(dev, "wakeup initialization failed (%d)\n", err);
 305                 /* ignore error and continue without wakeup support */
 306         }
 307
 308         return 0;
 309 }
 310
 311 static const struct of_device_id cpcap_rtc_of_match[] = {
 312         { .compatible = "motorola,cpcap-rtc", },
 313         {},
 314 };
 315 MODULE_DEVICE_TABLE(of, cpcap_rtc_of_match);
 316
 317 static struct platform_driver cpcap_rtc_driver = {
 318         .probe          = cpcap_rtc_probe,
 319         .driver         = {
 320                 .name   = "cpcap-rtc",
 321                 .of_match_table = cpcap_rtc_of_match,
 322         },
 323 };
 324
 325 module_platform_driver(cpcap_rtc_driver);
 326
 327 MODULE_ALIAS("platform:cpcap-rtc");
 328 MODULE_DESCRIPTION("CPCAP RTC driver");
 329 MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
 330 MODULE_LICENSE("GPL");