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/ab3100.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         struct ab3100 *ab3100_data = dev_get_drvdata(dev);
  49         u8 regs[] = {AB3100_TI0, AB3100_TI1, AB3100_TI2,
  50                      AB3100_TI3, AB3100_TI4, AB3100_TI5};
  51         unsigned char buf[6];
  52         u64 fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
  53         int err = 0;
  54         int i;
  55
  56         buf[0] = (fat_time) & 0xFF;
  57         buf[1] = (fat_time >> 8) & 0xFF;
  58         buf[2] = (fat_time >> 16) & 0xFF;
  59         buf[3] = (fat_time >> 24) & 0xFF;
  60         buf[4] = (fat_time >> 32) & 0xFF;
  61         buf[5] = (fat_time >> 40) & 0xFF;
  62
  63         for (i = 0; i < 6; i++) {
  64                 err = ab3100_set_register_interruptible(ab3100_data,
  65                                                         regs[i], buf[i]);
  66                 if (err)
  67                         return err;
  68         }
  69
  70         /* Set the flag to mark that the clock is now set */
  71         return ab3100_mask_and_set_register_interruptible(ab3100_data,
  72                                                           AB3100_RTC,
  73                                                           0xFE, 0x01);
  74
  75 }
  76
  77 static int ab3100_rtc_read_time(struct device *dev, struct rtc_time *tm)
  78 {
  79         struct ab3100 *ab3100_data = dev_get_drvdata(dev);
  80         unsigned long time;
  81         u8 rtcval;
  82         int err;
  83
  84         err = ab3100_get_register_interruptible(ab3100_data,
  85                                                 AB3100_RTC, &rtcval);
  86         if (err)
  87                 return err;
  88
  89         if (!(rtcval & 0x01)) {
  90                 dev_info(dev, "clock not set (lost power)");
  91                 return -EINVAL;
  92         } else {
  93                 u64 fat_time;
  94                 u8 buf[6];
  95
  96                 /* Read out time registers */
  97                 err = ab3100_get_register_page_interruptible(ab3100_data,
  98                                                              AB3100_TI0,
  99                                                              buf, 6);
 100                 if (err != 0)
 101                         return err;
 102
 103                 fat_time = ((u64) buf[5] << 40) | ((u64) buf[4] << 32) |
 104                         ((u64) buf[3] << 24) | ((u64) buf[2] << 16) |
 105                         ((u64) buf[1] << 8) | (u64) buf[0];
 106                 time = (unsigned long) (fat_time /
 107                                         (u64) (AB3100_RTC_CLOCK_RATE * 2));
 108         }
 109
 110         rtc_time_to_tm(time, tm);
 111
 112         return rtc_valid_tm(tm);
 113 }
 114
 115 static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 116 {
 117         struct ab3100 *ab3100_data = dev_get_drvdata(dev);
 118         unsigned long time;
 119         u64 fat_time;
 120         u8 buf[6];
 121         u8 rtcval;
 122         int err;
 123
 124         /* Figure out if alarm is enabled or not */
 125         err = ab3100_get_register_interruptible(ab3100_data,
 126                                                 AB3100_RTC, &rtcval);
 127         if (err)
 128                 return err;
 129         if (rtcval & 0x04)
 130                 alarm->enabled = 1;
 131         else
 132                 alarm->enabled = 0;
 133         /* No idea how this could be represented */
 134         alarm->pending = 0;
 135         /* Read out alarm registers, only 4 bytes */
 136         err = ab3100_get_register_page_interruptible(ab3100_data,
 137                                                      AB3100_AL0, buf, 4);
 138         if (err)
 139                 return err;
 140         fat_time = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
 141                 ((u64) buf[1] << 24) | ((u64) buf[0] << 16);
 142         time = (unsigned long) (fat_time / (u64) (AB3100_RTC_CLOCK_RATE * 2));
 143
 144         rtc_time_to_tm(time, &alarm->time);
 145
 146         return rtc_valid_tm(&alarm->time);
 147 }
 148
 149 static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 150 {
 151         struct ab3100 *ab3100_data = dev_get_drvdata(dev);
 152         u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
 153         unsigned char buf[4];
 154         unsigned long secs;
 155         u64 fat_time;
 156         int err;
 157         int i;
 158
 159         rtc_tm_to_time(&alarm->time, &secs);
 160         fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
 161         buf[0] = (fat_time >> 16) & 0xFF;
 162         buf[1] = (fat_time >> 24) & 0xFF;
 163         buf[2] = (fat_time >> 32) & 0xFF;
 164         buf[3] = (fat_time >> 40) & 0xFF;
 165
 166         /* Set the alarm */
 167         for (i = 0; i < 4; i++) {
 168                 err = ab3100_set_register_interruptible(ab3100_data,
 169                                                         regs[i], buf[i]);
 170                 if (err)
 171                         return err;
 172         }
 173         /* Then enable the alarm */
 174         return ab3100_mask_and_set_register_interruptible(ab3100_data,
 175                                                           AB3100_RTC, ~(1 << 2),
 176                                                           alarm->enabled << 2);
 177 }
 178
 179 static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
 180 {
 181         struct ab3100 *ab3100_data = dev_get_drvdata(dev);
 182
 183         /*
 184          * It's not possible to enable/disable the alarm IRQ for this RTC.
 185          * It does not actually trigger any IRQ: instead its only function is
 186          * to power up the system, if it wasn't on. This will manifest as
 187          * a "power up cause" in the AB3100 power driver (battery charging etc)
 188          * and need to be handled there instead.
 189          */
 190         if (enabled)
 191                 return ab3100_mask_and_set_register_interruptible(ab3100_data,
 192                                                     AB3100_RTC, ~(1 << 2),
 193                                                     1 << 2);
 194         else
 195                 return ab3100_mask_and_set_register_interruptible(ab3100_data,
 196                                                     AB3100_RTC, ~(1 << 2),
 197                                                     0);
 198 }
 199
 200 static const struct rtc_class_ops ab3100_rtc_ops = {
 201         .read_time      = ab3100_rtc_read_time,
 202         .set_mmss       = ab3100_rtc_set_mmss,
 203         .read_alarm     = ab3100_rtc_read_alarm,
 204         .set_alarm      = ab3100_rtc_set_alarm,
 205         .alarm_irq_enable = ab3100_rtc_irq_enable,
 206 };
 207
 208 static int __init ab3100_rtc_probe(struct platform_device *pdev)
 209 {
 210         int err;
 211         u8 regval;
 212         struct rtc_device *rtc;
 213         struct ab3100 *ab3100_data = platform_get_drvdata(pdev);
 214
 215         /* The first RTC register needs special treatment */
 216         err = ab3100_get_register_interruptible(ab3100_data,
 217                                                 AB3100_RTC, &regval);
 218         if (err) {
 219                 dev_err(&pdev->dev, "unable to read RTC register\n");
 220                 return -ENODEV;
 221         }
 222
 223         if ((regval & 0xFE) != RTC_SETTING) {
 224                 dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
 225                          regval);
 226         }
 227
 228         if ((regval & 1) == 0) {
 229                 /*
 230                  * Set bit to detect power loss.
 231                  * This bit remains until RTC power is lost.
 232                  */
 233                 regval = 1 | RTC_SETTING;
 234                 err = ab3100_set_register_interruptible(ab3100_data,
 235                                                         AB3100_RTC, regval);
 236                 /* Ignore any error on this write */
 237         }
 238
 239         rtc = rtc_device_register("ab3100-rtc", &pdev->dev, &ab3100_rtc_ops,
 240                                   THIS_MODULE);
 241         if (IS_ERR(rtc)) {
 242                 err = PTR_ERR(rtc);
 243                 return err;
 244         }
 245
 246         return 0;
 247 }
 248
 249 static int __exit ab3100_rtc_remove(struct platform_device *pdev)
 250 {
 251         struct rtc_device *rtc = platform_get_drvdata(pdev);
 252
 253         rtc_device_unregister(rtc);
 254         return 0;
 255 }
 256
 257 static struct platform_driver ab3100_rtc_driver = {
 258         .driver = {
 259                 .name = "ab3100-rtc",
 260                 .owner = THIS_MODULE,
 261         },
 262         .remove  = __exit_p(ab3100_rtc_remove),
 263 };
 264
 265 static int __init ab3100_rtc_init(void)
 266 {
 267         return platform_driver_probe(&ab3100_rtc_driver,
 268                                      ab3100_rtc_probe);
 269 }
 270
 271 static void __exit ab3100_rtc_exit(void)
 272 {
 273         platform_driver_unregister(&ab3100_rtc_driver);
 274 }
 275
 276 module_init(ab3100_rtc_init);
 277 module_exit(ab3100_rtc_exit);
 278
 279 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 280 MODULE_DESCRIPTION("AB3100 RTC Driver");
 281 MODULE_LICENSE("GPL");