Switch to external clock source during suspend and switch back
to internal source on resume. This helps rtc ticking across suspend.
Signed-off-by: Keerthy <j-keerthy@xxxxxx>
---
arch/arm/boot/dts/am4372.dtsi | 2 ++
drivers/rtc/rtc-omap.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/arch/arm/boot/dts/am4372.dtsi b/arch/arm/boot/dts/am4372.dtsi
index d99b2ee..756819f 100644
--- a/arch/arm/boot/dts/am4372.dtsi
+++ b/arch/arm/boot/dts/am4372.dtsi
@@ -336,6 +336,8 @@
interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH
GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>;
ti,hwmods = "rtc";
+ clocks = <&clk_32768_ck>, <&clk_32k_rtc>;
+ clock-names = "int-clk", "ext-clk";
status = "disabled";
};
diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index 8b6355f..cfc8558 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -25,6 +25,7 @@
#include <linux/of_device.h>
#include <linux/pm_runtime.h>
#include <linux/io.h>
+#include <linux/clk.h>
/*
* The OMAP RTC is a year/month/day/hours/minutes/seconds BCD clock
@@ -107,6 +108,7 @@
/* OMAP_RTC_OSC_REG bit fields: */
#define OMAP_RTC_OSC_32KCLK_EN BIT(6)
+#define OMAP_RTC_OSC_SEL_32KCLK_SRC BIT(3)
/* OMAP_RTC_IRQWAKEEN bit fields: */
#define OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN BIT(1)
@@ -136,6 +138,7 @@ struct omap_rtc {
int irq_timer;
u8 interrupts_reg;
bool is_pmic_controller;
+ bool has_ext_clk;
const struct omap_rtc_device_type *type;
};
@@ -525,6 +528,7 @@ static int omap_rtc_probe(struct platform_device *pdev)
{
struct omap_rtc *rtc;
struct resource *res;
+ struct clk *ext_clk;
u8 reg, mask, new_ctrl;
const struct platform_device_id *id_entry;
const struct of_device_id *of_id;
@@ -553,6 +557,10 @@ static int omap_rtc_probe(struct platform_device *pdev)
if (rtc->irq_alarm <= 0)
return -ENOENT;
+ ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
+ if (!IS_ERR(ext_clk))
+ rtc->has_ext_clk = true;
+
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
rtc->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(rtc->base))
@@ -698,6 +706,7 @@ static int __exit omap_rtc_remove(struct platform_device *pdev)
static int omap_rtc_suspend(struct device *dev)
{
struct omap_rtc *rtc = dev_get_drvdata(dev);
+ u8 reg;
rtc->interrupts_reg = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
@@ -711,6 +720,18 @@ static int omap_rtc_suspend(struct device *dev)
enable_irq_wake(rtc->irq_alarm);
else
rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, 0);
+
+ /*
+ * If we have the luxury of external clock then
+ * Switch to external clock so we can keep ticking
+ * acorss suspend
+ */
+ if (rtc->has_ext_clk) {
+ reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
+ rtc_write(rtc, OMAP_RTC_OSC_REG, reg |
+ OMAP_RTC_OSC_SEL_32KCLK_SRC);
+ }
+
rtc->type->lock(rtc);
/* Disable the clock/module */
@@ -722,6 +743,7 @@ static int omap_rtc_suspend(struct device *dev)
static int omap_rtc_resume(struct device *dev)
{
struct omap_rtc *rtc = dev_get_drvdata(dev);
+ u8 reg;
/* Enable the clock/module so that we can access the registers */
pm_runtime_get_sync(dev);
@@ -731,6 +753,15 @@ static int omap_rtc_resume(struct device *dev)
disable_irq_wake(rtc->irq_alarm);
else
rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, rtc->interrupts_reg);
+ /*
+ * Switch back to internal source
+ */
+ if (rtc->has_ext_clk) {
+ reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
+ reg &= ~OMAP_RTC_OSC_SEL_32KCLK_SRC;
+ rtc_write(rtc, OMAP_RTC_OSC_REG, reg);
+ }
+
rtc->type->lock(rtc);
return 0;
--
1.9.1
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