drivers/rtc/rtc-ab3100.c

   1 /*
   2  * Copyright (C) 2007-2009 ST-Ericsson AB
   3  * License terms: GNU General Public License (GPL) version 2
   4  * RTC clock driver for the AB3100 Analog Baseband Chip
   5  * Author: Linus Walleij <linus.walleij@stericsson.com>
   6  */
   7 #include <linux/module.h>
   8 #include <linux/kernel.h>
   9 #include <linux/init.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/rtc.h>
  12 #include <linux/mfd/abx500.h>
  13
  14 /* Clock rate in Hz */
  15 #define AB3100_RTC_CLOCK_RATE   32768
  16
  17 /*
  18  * The AB3100 RTC registers. These are the same for
  19  * AB3000 and AB3100.
  20  * Control register:
  21  * Bit 0: RTC Monitor cleared=0, active=1, if you set it
  22  *        to 1 it remains active until RTC power is lost.
  23  * Bit 1: 32 kHz Oscillator, 0 = on, 1 = bypass
  24  * Bit 2: Alarm on, 0 = off, 1 = on
  25  * Bit 3: 32 kHz buffer disabling, 0 = enabled, 1 = disabled
  26  */
  27 #define AB3100_RTC              0x53
  28 /* default setting, buffer disabled, alarm on */
  29 #define RTC_SETTING             0x30
  30 /* Alarm when AL0-AL3 == TI0-TI3  */
  31 #define AB3100_AL0              0x56
  32 #define AB3100_AL1              0x57
  33 #define AB3100_AL2              0x58
  34 #define AB3100_AL3              0x59
  35 /* This 48-bit register that counts up at 32768 Hz */
  36 #define AB3100_TI0              0x5a
  37 #define AB3100_TI1              0x5b
  38 #define AB3100_TI2              0x5c
  39 #define AB3100_TI3              0x5d
  40 #define AB3100_TI4              0x5e
  41 #define AB3100_TI5              0x5f
  42
  43 /*
  44  * RTC clock functions and device struct declaration
  45  */
  46 static int ab3100_rtc_set_mmss(struct device *dev, unsigned long secs)
  47 {
  48         u8 regs[] = {AB3100_TI0, AB3100_TI1, AB3100_TI2,
  49                      AB3100_TI3, AB3100_TI4, AB3100_TI5};
  50         unsigned char buf[6];
  51         u64 fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
  52         int err = 0;
  53         int i;
  54
  55         buf[0] = (fat_time) & 0xFF;
  56         buf[1] = (fat_time >> 8) & 0xFF;
  57         buf[2] = (fat_time >> 16) & 0xFF;
  58         buf[3] = (fat_time >> 24) & 0xFF;
  59         buf[4] = (fat_time >> 32) & 0xFF;
  60         buf[5] = (fat_time >> 40) & 0xFF;
  61
  62         for (i = 0; i < 6; i++) {
  63                 err = abx500_set_register_interruptible(dev, 0,
  64                                                         regs[i], buf[i]);
  65                 if (err)
  66                         return err;
  67         }
  68
  69         /* Set the flag to mark that the clock is now set */
  70         return abx500_mask_and_set_register_interruptible(dev, 0,
  71                                                           AB3100_RTC,
  72                                                           0x01, 0x01);
  73
  74 }
  75
  76 static int ab3100_rtc_read_time(struct device *dev, struct rtc_time *tm)
  77 {
  78         unsigned long time;
  79         u8 rtcval;
  80         int err;
  81
  82         err = abx500_get_register_interruptible(dev, 0,
  83                                                 AB3100_RTC, &rtcval);
  84         if (err)
  85                 return err;
  86
  87         if (!(rtcval & 0x01)) {
  88                 dev_info(dev, "clock not set (lost power)");
  89                 return -EINVAL;
  90         } else {
  91                 u64 fat_time;
  92                 u8 buf[6];
  93
  94                 /* Read out time registers */
  95                 err = abx500_get_register_page_interruptible(dev, 0,
  96                                                              AB3100_TI0,
  97                                                              buf, 6);
  98                 if (err != 0)
  99                         return err;
 100
 101                 fat_time = ((u64) buf[5] << 40) | ((u64) buf[4] << 32) |
 102                         ((u64) buf[3] << 24) | ((u64) buf[2] << 16) |
 103                         ((u64) buf[1] << 8) | (u64) buf[0];
 104                 time = (unsigned long) (fat_time /
 105                                         (u64) (AB3100_RTC_CLOCK_RATE * 2));
 106         }
 107
 108         rtc_time_to_tm(time, tm);
 109
 110         return rtc_valid_tm(tm);
 111 }
 112
 113 static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 114 {
 115         unsigned long time;
 116         u64 fat_time;
 117         u8 buf[6];
 118         u8 rtcval;
 119         int err;
 120
 121         /* Figure out if alarm is enabled or not */
 122         err = abx500_get_register_interruptible(dev, 0,
 123                                                 AB3100_RTC, &rtcval);
 124         if (err)
 125                 return err;
 126         if (rtcval & 0x04)
 127                 alarm->enabled = 1;
 128         else
 129                 alarm->enabled = 0;
 130         /* No idea how this could be represented */
 131         alarm->pending = 0;
 132         /* Read out alarm registers, only 4 bytes */
 133         err = abx500_get_register_page_interruptible(dev, 0,
 134                                                      AB3100_AL0, buf, 4);
 135         if (err)
 136                 return err;
 137         fat_time = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
 138                 ((u64) buf[1] << 24) | ((u64) buf[0] << 16);
 139         time = (unsigned long) (fat_time / (u64) (AB3100_RTC_CLOCK_RATE * 2));
 140
 141         rtc_time_to_tm(time, &alarm->time);
 142
 143         return rtc_valid_tm(&alarm->time);
 144 }
 145
 146 static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 147 {
 148         u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
 149         unsigned char buf[4];
 150         unsigned long secs;
 151         u64 fat_time;
 152         int err;
 153         int i;
 154
 155         rtc_tm_to_time(&alarm->time, &secs);
 156         fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
 157         buf[0] = (fat_time >> 16) & 0xFF;
 158         buf[1] = (fat_time >> 24) & 0xFF;
 159         buf[2] = (fat_time >> 32) & 0xFF;
 160         buf[3] = (fat_time >> 40) & 0xFF;
 161
 162         /* Set the alarm */
 163         for (i = 0; i < 4; i++) {
 164                 err = abx500_set_register_interruptible(dev, 0,
 165                                                         regs[i], buf[i]);
 166                 if (err)
 167                         return err;
 168         }
 169         /* Then enable the alarm */
 170         return abx500_mask_and_set_register_interruptible(dev, 0,
 171                                                           AB3100_RTC, (1 << 2),
 172                                                           alarm->enabled << 2);
 173 }
 174
 175 static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
 176 {
 177         /*
 178          * It's not possible to enable/disable the alarm IRQ for this RTC.
 179          * It does not actually trigger any IRQ: instead its only function is
 180          * to power up the system, if it wasn't on. This will manifest as
 181          * a "power up cause" in the AB3100 power driver (battery charging etc)
 182          * and need to be handled there instead.
 183          */
 184         if (enabled)
 185                 return abx500_mask_and_set_register_interruptible(dev, 0,
 186                                                     AB3100_RTC, (1 << 2),
 187                                                     1 << 2);
 188         else
 189                 return abx500_mask_and_set_register_interruptible(dev, 0,
 190                                                     AB3100_RTC, (1 << 2),
 191                                                     0);
 192 }
 193
 194 static const struct rtc_class_ops ab3100_rtc_ops = {
 195         .read_time      = ab3100_rtc_read_time,
 196         .set_mmss       = ab3100_rtc_set_mmss,
 197         .read_alarm     = ab3100_rtc_read_alarm,
 198         .set_alarm      = ab3100_rtc_set_alarm,
 199         .alarm_irq_enable = ab3100_rtc_irq_enable,
 200 };
 201
 202 static int __init ab3100_rtc_probe(struct platform_device *pdev)
 203 {
 204         int err;
 205         u8 regval;
 206         struct rtc_device *rtc;
 207
 208         /* The first RTC register needs special treatment */
 209         err = abx500_get_register_interruptible(&pdev->dev, 0,
 210                                                 AB3100_RTC, &regval);
 211         if (err) {
 212                 dev_err(&pdev->dev, "unable to read RTC register\n");
 213                 return -ENODEV;
 214         }
 215
 216         if ((regval & 0xFE) != RTC_SETTING) {
 217                 dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
 218                          regval);
 219         }
 220
 221         if ((regval & 1) == 0) {
 222                 /*
 223                  * Set bit to detect power loss.
 224                  * This bit remains until RTC power is lost.
 225                  */
 226                 regval = 1 | RTC_SETTING;
 227                 err = abx500_set_register_interruptible(&pdev->dev, 0,
 228                                                         AB3100_RTC, regval);
 229                 /* Ignore any error on this write */
 230         }
 231
 232         rtc = devm_rtc_device_register(&pdev->dev, "ab3100-rtc",
 233                                         &ab3100_rtc_ops, THIS_MODULE);
 234         if (IS_ERR(rtc)) {
 235                 err = PTR_ERR(rtc);
 236                 return err;
 237         }
 238         platform_set_drvdata(pdev, rtc);
 239
 240         return 0;
 241 }
 242
 243 static struct platform_driver ab3100_rtc_driver = {
 244         .driver = {
 245                 .name = "ab3100-rtc",
 246         },
 247 };
 248
 249 module_platform_driver_probe(ab3100_rtc_driver, ab3100_rtc_probe);
 250
 251 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 252 MODULE_DESCRIPTION("AB3100 RTC Driver");
 253 MODULE_LICENSE("GPL");