drivers/rtc/rtc-rtd119x.c

   1 /*
   2  * Realtek RTD129x RTC
   3  *
   4  * Copyright (c) 2017 Andreas Färber
   5  *
   6  * SPDX-License-Identifier: GPL-2.0+
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/io.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/of_address.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/rtc.h>
  16 #include <linux/spinlock.h>
  17
  18 #define RTD_RTCSEC              0x00
  19 #define RTD_RTCMIN              0x04
  20 #define RTD_RTCHR               0x08
  21 #define RTD_RTCDATE1            0x0c
  22 #define RTD_RTCDATE2            0x10
  23 #define RTD_RTCACR              0x28
  24 #define RTD_RTCEN               0x2c
  25 #define RTD_RTCCR               0x30
  26
  27 #define RTD_RTCSEC_RTCSEC_MASK          0x7f
  28
  29 #define RTD_RTCMIN_RTCMIN_MASK          0x3f
  30
  31 #define RTD_RTCHR_RTCHR_MASK            0x1f
  32
  33 #define RTD_RTCDATE1_RTCDATE1_MASK      0xff
  34
  35 #define RTD_RTCDATE2_RTCDATE2_MASK      0x7f
  36
  37 #define RTD_RTCACR_RTCPWR               BIT(7)
  38
  39 #define RTD_RTCEN_RTCEN_MASK            0xff
  40
  41 #define RTD_RTCCR_RTCRST                BIT(6)
  42
  43 struct rtd119x_rtc {
  44         void __iomem *base;
  45         struct clk *clk;
  46         struct rtc_device *rtcdev;
  47         unsigned int base_year;
  48 };
  49
  50 static inline int rtd119x_rtc_days_in_year(int year)
  51 {
  52         return 365 + (is_leap_year(year) ? 1 : 0);
  53 }
  54
  55 static void rtd119x_rtc_reset(struct device *dev)
  56 {
  57         struct rtd119x_rtc *data = dev_get_drvdata(dev);
  58         u32 val;
  59
  60         val = readl_relaxed(data->base + RTD_RTCCR);
  61         val |= RTD_RTCCR_RTCRST;
  62         writel_relaxed(val, data->base + RTD_RTCCR);
  63
  64         val &= ~RTD_RTCCR_RTCRST;
  65         writel(val, data->base + RTD_RTCCR);
  66 }
  67
  68 static void rtd119x_rtc_set_enabled(struct device *dev, bool enable)
  69 {
  70         struct rtd119x_rtc *data = dev_get_drvdata(dev);
  71         u32 val;
  72
  73         val = readl_relaxed(data->base + RTD_RTCEN);
  74         if (enable) {
  75                 if ((val & RTD_RTCEN_RTCEN_MASK) == 0x5a)
  76                         return;
  77                 writel_relaxed(0x5a, data->base + RTD_RTCEN);
  78         } else {
  79                 writel_relaxed(0, data->base + RTD_RTCEN);
  80         }
  81 }
  82
  83 static int rtd119x_rtc_read_time(struct device *dev, struct rtc_time *tm)
  84 {
  85         struct rtd119x_rtc *data = dev_get_drvdata(dev);
  86         s32 day;
  87         u32 sec;
  88         unsigned int year;
  89         int tries = 0;
  90
  91         while (true) {
  92                 tm->tm_sec = (readl_relaxed(data->base + RTD_RTCSEC) & RTD_RTCSEC_RTCSEC_MASK) >> 1;
  93                 tm->tm_min  = readl_relaxed(data->base + RTD_RTCMIN) & RTD_RTCMIN_RTCMIN_MASK;
  94                 tm->tm_hour = readl_relaxed(data->base + RTD_RTCHR) & RTD_RTCHR_RTCHR_MASK;
  95                 day  =  readl_relaxed(data->base + RTD_RTCDATE1) & RTD_RTCDATE1_RTCDATE1_MASK;
  96                 day |= (readl_relaxed(data->base + RTD_RTCDATE2) & RTD_RTCDATE2_RTCDATE2_MASK) << 8;
  97                 sec  = (readl_relaxed(data->base + RTD_RTCSEC) & RTD_RTCSEC_RTCSEC_MASK) >> 1;
  98                 tries++;
  99
 100                 if (sec == tm->tm_sec)
 101                         break;
 102
 103                 if (tries >= 3)
 104                         return -EINVAL;
 105         }
 106         if (tries > 1)
 107                 dev_dbg(dev, "%s: needed %i tries\n", __func__, tries);
 108
 109         year = data->base_year;
 110         while (day >= rtd119x_rtc_days_in_year(year)) {
 111                 day -= rtd119x_rtc_days_in_year(year);
 112                 year++;
 113         }
 114         tm->tm_year = year - 1900;
 115         tm->tm_yday = day;
 116
 117         tm->tm_mon = 0;
 118         while (day >= rtc_month_days(tm->tm_mon, year)) {
 119                 day -= rtc_month_days(tm->tm_mon, year);
 120                 tm->tm_mon++;
 121         }
 122         tm->tm_mday = day + 1;
 123
 124         return 0;
 125 }
 126
 127 static int rtd119x_rtc_set_time(struct device *dev, struct rtc_time *tm)
 128 {
 129         struct rtd119x_rtc *data = dev_get_drvdata(dev);
 130         unsigned int day;
 131         int i;
 132
 133         if (1900 + tm->tm_year < data->base_year)
 134                 return -EINVAL;
 135
 136         day = 0;
 137         for (i = data->base_year; i < 1900 + tm->tm_year; i++)
 138                 day += rtd119x_rtc_days_in_year(i);
 139
 140         day += tm->tm_yday;
 141         if (day > 0x7fff)
 142                 return -EINVAL;
 143
 144         rtd119x_rtc_set_enabled(dev, false);
 145
 146         writel_relaxed((tm->tm_sec << 1) & RTD_RTCSEC_RTCSEC_MASK, data->base + RTD_RTCSEC);
 147         writel_relaxed(tm->tm_min & RTD_RTCMIN_RTCMIN_MASK, data->base + RTD_RTCMIN);
 148         writel_relaxed(tm->tm_hour & RTD_RTCHR_RTCHR_MASK, data->base + RTD_RTCHR);
 149         writel_relaxed(day & RTD_RTCDATE1_RTCDATE1_MASK, data->base + RTD_RTCDATE1);
 150         writel_relaxed((day >> 8) & RTD_RTCDATE2_RTCDATE2_MASK, data->base + RTD_RTCDATE2);
 151
 152         rtd119x_rtc_set_enabled(dev, true);
 153
 154         return 0;
 155 }
 156
 157 static const struct rtc_class_ops rtd119x_rtc_ops = {
 158         .read_time      = rtd119x_rtc_read_time,
 159         .set_time       = rtd119x_rtc_set_time,
 160 };
 161
 162 static const struct of_device_id rtd119x_rtc_dt_ids[] = {
 163          { .compatible = "realtek,rtd1295-rtc" },
 164          { }
 165 };
 166
 167 static int rtd119x_rtc_probe(struct platform_device *pdev)
 168 {
 169         struct rtd119x_rtc *data;
 170         u32 val;
 171         int ret;
 172
 173         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 174         if (!data)
 175                 return -ENOMEM;
 176
 177         platform_set_drvdata(pdev, data);
 178         data->base_year = 2014;
 179
 180         data->base = devm_platform_ioremap_resource(pdev, 0);
 181         if (IS_ERR(data->base))
 182                 return PTR_ERR(data->base);
 183
 184         data->clk = of_clk_get(pdev->dev.of_node, 0);
 185         if (IS_ERR(data->clk))
 186                 return PTR_ERR(data->clk);
 187
 188         ret = clk_prepare_enable(data->clk);
 189         if (ret) {
 190                 clk_put(data->clk);
 191                 return ret;
 192         }
 193
 194         val = readl_relaxed(data->base + RTD_RTCACR);
 195         if (!(val & RTD_RTCACR_RTCPWR)) {
 196                 writel_relaxed(RTD_RTCACR_RTCPWR, data->base + RTD_RTCACR);
 197
 198                 rtd119x_rtc_reset(&pdev->dev);
 199
 200                 writel_relaxed(0, data->base + RTD_RTCMIN);
 201                 writel_relaxed(0, data->base + RTD_RTCHR);
 202                 writel_relaxed(0, data->base + RTD_RTCDATE1);
 203                 writel_relaxed(0, data->base + RTD_RTCDATE2);
 204         }
 205
 206         rtd119x_rtc_set_enabled(&pdev->dev, true);
 207
 208         data->rtcdev = devm_rtc_device_register(&pdev->dev, "rtc",
 209                                                 &rtd119x_rtc_ops, THIS_MODULE);
 210         if (IS_ERR(data->rtcdev)) {
 211                 dev_err(&pdev->dev, "failed to register rtc device");
 212                 clk_disable_unprepare(data->clk);
 213                 clk_put(data->clk);
 214                 return PTR_ERR(data->rtcdev);
 215         }
 216
 217         return 0;
 218 }
 219
 220 static int rtd119x_rtc_remove(struct platform_device *pdev)
 221 {
 222         struct rtd119x_rtc *data = platform_get_drvdata(pdev);
 223
 224         rtd119x_rtc_set_enabled(&pdev->dev, false);
 225
 226         clk_disable_unprepare(data->clk);
 227         clk_put(data->clk);
 228
 229         return 0;
 230 }
 231
 232 static struct platform_driver rtd119x_rtc_driver = {
 233         .probe = rtd119x_rtc_probe,
 234         .remove = rtd119x_rtc_remove,
 235         .driver = {
 236                 .name = "rtd1295-rtc",
 237                 .of_match_table = rtd119x_rtc_dt_ids,
 238         },
 239 };
 240 builtin_platform_driver(rtd119x_rtc_driver);