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

From f05b1ecd7e4fde7e69320a4b7be461636e982991 Mon Sep 17 00:00:00 2001
From: Paul Cercueil <paul@crapouillou.net>
Date: Thu, 13 Sep 2012 00:09:20 +0200
Subject: [PATCH 5/7] RTC: JZ4740: Init the "regulator" register on startup.

This register controls the accuracy of the RTC. uC/OS-II use
the RTC as a 100Hz clock, and writes a completely wrong value
on that register, that we have to overwrite if we want a working
real-time clock.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/rtc/rtc-jz4740.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

--- a/drivers/rtc/rtc-jz4740.c
+++ b/drivers/rtc/rtc-jz4740.c
@@ -15,6 +15,7 @@
  */
 
 #include <linux/io.h>
+#include <linux/clk.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
@@ -216,6 +217,7 @@ static int jz4740_rtc_probe(struct platf
 	struct jz4740_rtc *rtc;
 	uint32_t scratchpad;
 	struct resource *mem;
+	struct clk *rtc_clk;
 
 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
 	if (!rtc)
@@ -263,6 +265,21 @@ static int jz4740_rtc_probe(struct platf
 		}
 	}
 
+	rtc_clk = clk_get(&pdev->dev, "rtc");
+	if (IS_ERR(rtc_clk)) {
+		dev_err(&pdev->dev, "Failed to get RTC clock\n");
+		return PTR_ERR(rtc_clk);
+	}
+
+	/* TODO: initialize the ADJC bits (25:16) to fine-tune
+	 * the accuracy of the RTC */
+	ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_REGULATOR,
+				(clk_get_rate(rtc_clk) - 1) & 0xffff);
+	clk_put(rtc_clk);
+
+	if (ret)
+		dev_warn(&pdev->dev, "Could not update RTC regulator register\n");
+
 	return 0;
 }