drivers/rtc/rtc-88pm886.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/limits.h>
   3 #include <linux/mod_devicetable.h>
   4 #include <linux/platform_device.h>
   5 #include <linux/rtc.h>
   6
   7 #include <linux/mfd/88pm886.h>
   8
   9 /*
  10  * Time is calculated as the sum of a 32-bit read-only advancing counter and a
  11  * writeable constant offset stored in the chip's spare registers.
  12  */
  13
  14 static int pm886_rtc_read_time(struct device *dev, struct rtc_time *tm)
  15 {
  16         struct regmap *regmap = dev_get_drvdata(dev);
  17         u32 time;
  18         u32 buf;
  19         int ret;
  20
  21         ret = regmap_bulk_read(regmap, PM886_REG_RTC_SPARE1, &buf, 4);
  22         if (ret)
  23                 return ret;
  24         time = buf;
  25
  26         ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4);
  27         if (ret)
  28                 return ret;
  29         time += buf;
  30
  31         rtc_time64_to_tm(time, tm);
  32
  33         return 0;
  34 }
  35
  36 static int pm886_rtc_set_time(struct device *dev, struct rtc_time *tm)
  37 {
  38         struct regmap *regmap = dev_get_drvdata(dev);
  39         u32 buf;
  40         int ret;
  41
  42         ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4);
  43         if (ret)
  44                 return ret;
  45
  46         buf = rtc_tm_to_time64(tm) - buf;
  47
  48         return regmap_bulk_write(regmap, PM886_REG_RTC_SPARE1, &buf, 4);
  49 }
  50
  51 static const struct rtc_class_ops pm886_rtc_ops = {
  52         .read_time = pm886_rtc_read_time,
  53         .set_time = pm886_rtc_set_time,
  54 };
  55
  56 static int pm886_rtc_probe(struct platform_device *pdev)
  57 {
  58         struct pm886_chip *chip = dev_get_drvdata(pdev->dev.parent);
  59         struct device *dev = &pdev->dev;
  60         struct rtc_device *rtc;
  61         int ret;
  62
  63         platform_set_drvdata(pdev, chip->regmap);
  64
  65         rtc = devm_rtc_allocate_device(dev);
  66         if (IS_ERR(rtc))
  67                 return dev_err_probe(dev, PTR_ERR(rtc),
  68                                 "Failed to allocate RTC device\n");
  69
  70         rtc->ops = &pm886_rtc_ops;
  71         rtc->range_max = U32_MAX;
  72
  73         ret = devm_rtc_register_device(rtc);
  74         if (ret)
  75                 return dev_err_probe(dev, ret, "Failed to register RTC device\n");
  76
  77         return 0;
  78 }
  79
  80 static const struct platform_device_id pm886_rtc_id_table[] = {
  81         { "88pm886-rtc", },
  82         { }
  83 };
  84 MODULE_DEVICE_TABLE(platform, pm886_rtc_id_table);
  85
  86 static struct platform_driver pm886_rtc_driver = {
  87         .driver = {
  88                 .name = "88pm886-rtc",
  89         },
  90         .probe = pm886_rtc_probe,
  91         .id_table = pm886_rtc_id_table,
  92 };
  93 module_platform_driver(pm886_rtc_driver);
  94
  95 MODULE_DESCRIPTION("Marvell 88PM886 RTC driver");
  96 MODULE_AUTHOR("Karel Balej <balejk@matfyz.cz>");
  97 MODULE_LICENSE("GPL");