target/linux/mvebu/patches-4.14/421-rtc-initialize.patch

   1 Some boards like the Turris Omnia have an RTC chip that does not get
   2 initialized. Initializing the RTC at the driver level helps get rid of
   3 bootloader hacks that write special register values.
   4
   5 --- a/drivers/rtc/rtc-armada38x.c
   6 +++ b/drivers/rtc/rtc-armada38x.c
   7 @@ -30,6 +30,9 @@
   8  #define RTC_IRQ_FREQ_1HZ           BIT(2)
   9  #define RTC_CCR                    0x18
  10  #define RTC_CCR_MODE               BIT(15)
  11 +#define RTC_CCR_NORMAL_PPB         0x2000
  12 +#define RTC_TEST_CONF              0x1c
  13 +#define RTC_TEST_CONF_MASK         0xff
  14
  15  #define RTC_TIME           0xC
  16  #define RTC_ALARM1         0x10
  17 @@ -91,6 +94,7 @@ struct armada38x_rtc_data {
  18         void (*clear_isr)(struct armada38x_rtc *rtc);
  19         void (*unmask_interrupt)(struct armada38x_rtc *rtc);
  20         u32 alarm;
  21 +       void (*init_rtc)(struct armada38x_rtc *rtc);
  22  };
  23
  24  /*
  25 @@ -202,6 +206,23 @@ static void armada38x_unmask_interrupt(s
  26         writel(val | SOC_RTC_ALARM1_MASK, rtc->regs_soc + SOC_RTC_INTERRUPT);
  27  }
  28
  29 +static void armada38x_rtc_init(struct armada38x_rtc *rtc)
  30 +{
  31 +       u32 reg;
  32 +
  33 +       /* Test RTC test configuration register bits [7:0] */
  34 +       reg = readl(rtc->regs + RTC_TEST_CONF);
  35 +       /* If bits [7:0] are non-zero, assume RTC was uninitialized */
  36 +       if (reg & RTC_TEST_CONF_MASK) {
  37 +               rtc_delayed_write(0, rtc, RTC_TEST_CONF);
  38 +               rtc_delayed_write(0, rtc, RTC_TIME);
  39 +               rtc_delayed_write((RTC_STATUS_ALARM1 | RTC_STATUS_ALARM2),
  40 +                               rtc, RTC_STATUS);
  41 +               rtc_delayed_write(RTC_CCR_NORMAL_PPB, rtc, RTC_CCR);
  42 +       }
  43 +       return;
  44 +}
  45 +
  46  static void armada8k_clear_isr(struct armada38x_rtc *rtc)
  47  {
  48         writel(RTC_8K_ALARM2, rtc->regs_soc + RTC_8K_ISR);
  49 @@ -464,6 +485,7 @@ static const struct armada38x_rtc_data a
  50         .clear_isr = armada38x_clear_isr,
  51         .unmask_interrupt = armada38x_unmask_interrupt,
  52         .alarm = ALARM1,
  53 +       .init_rtc = armada38x_rtc_init,
  54  };
  55
  56  static const struct armada38x_rtc_data armada8k_data = {
  57 @@ -558,6 +580,17 @@ static __init int armada38x_rtc_probe(st
  58                 dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
  59                 return ret;
  60         }
  61 +
  62 +       /*
  63 +        * Try to detect if RTC is in uninitialized state.
  64 +        * It is not definitive to know if the RTC is in an uninialized state or not,
  65 +        * but the following call will read some bits in the RTC unit and guess if
  66 +        * if it's in that state, and accordingly set it to sane default values.
  67 +        */
  68 +       if (rtc->data->init_rtc) {
  69 +               rtc->data->init_rtc(rtc);
  70 +       }
  71 +
  72         return 0;
  73  }
  74