target/linux/xburst/patches-3.18/005-RTC-JZ4740-Init-the-regulator-register-on-startup.patch

   1 From f05b1ecd7e4fde7e69320a4b7be461636e982991 Mon Sep 17 00:00:00 2001
   2 From: Paul Cercueil <paul@crapouillou.net>
   3 Date: Thu, 13 Sep 2012 00:09:20 +0200
   4 Subject: [PATCH 5/7] RTC: JZ4740: Init the "regulator" register on startup.
   5
   6 This register controls the accuracy of the RTC. uC/OS-II use
   7 the RTC as a 100Hz clock, and writes a completely wrong value
   8 on that register, that we have to overwrite if we want a working
   9 real-time clock.
  10
  11 Signed-off-by: Paul Cercueil <paul@crapouillou.net>
  12 ---
  13  drivers/rtc/rtc-jz4740.c |   17 +++++++++++++++++
  14  1 file changed, 17 insertions(+)
  15
  16 --- a/drivers/rtc/rtc-jz4740.c
  17 +++ b/drivers/rtc/rtc-jz4740.c
  18 @@ -15,6 +15,7 @@
  19   */
  20
  21  #include <linux/io.h>
  22 +#include <linux/clk.h>
  23  #include <linux/kernel.h>
  24  #include <linux/module.h>
  25  #include <linux/platform_device.h>
  26 @@ -216,6 +217,7 @@ static int jz4740_rtc_probe(struct platf
  27         struct jz4740_rtc *rtc;
  28         uint32_t scratchpad;
  29         struct resource *mem;
  30 +       struct clk *rtc_clk;
  31
  32         rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
  33         if (!rtc)
  34 @@ -263,6 +265,21 @@ static int jz4740_rtc_probe(struct platf
  35                 }
  36         }
  37
  38 +       rtc_clk = clk_get(&pdev->dev, "rtc");
  39 +       if (IS_ERR(rtc_clk)) {
  40 +               dev_err(&pdev->dev, "Failed to get RTC clock\n");
  41 +               return PTR_ERR(rtc_clk);
  42 +       }
  43 +
  44 +       /* TODO: initialize the ADJC bits (25:16) to fine-tune
  45 +        * the accuracy of the RTC */
  46 +       ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_REGULATOR,
  47 +                               (clk_get_rate(rtc_clk) - 1) & 0xffff);
  48 +       clk_put(rtc_clk);
  49 +
  50 +       if (ret)
  51 +               dev_warn(&pdev->dev, "Could not update RTC regulator register\n");
  52 +
  53         return 0;
  54  }
  55