rtc: omap: Add external clock enabling support

Configure the clock source to external clock if available.
External clock is preferred as it can be ticking during suspend.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

1 files changed, 24 insertions, 1 deletions

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index f31c0127dae0..ec2e9c5fb993 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -108,6 +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)
@@ -138,6 +139,7 @@ struct omap_rtc {
         int irq_timer;
         u8 interrupts_reg;
         bool is_pmic_controller;
+        bool has_ext_clk;
         const struct omap_rtc_device_type *type;
 };
 
@@ -555,7 +557,11 @@ static int omap_rtc_probe(struct platform_device *pdev)
         if (rtc->irq_alarm <= 0)
                 return -ENOENT;
 
-        rtc->clk = devm_clk_get(&pdev->dev, "int-clk");
+        rtc->clk = devm_clk_get(&pdev->dev, "ext-clk");
+        if (!IS_ERR(rtc->clk))
+                rtc->has_ext_clk = true;
+        else
+                rtc->clk = devm_clk_get(&pdev->dev, "int-clk");
 
         if (!IS_ERR(rtc->clk))
                 clk_prepare_enable(rtc->clk);
@@ -634,6 +640,16 @@ static int omap_rtc_probe(struct platform_device *pdev)
         if (reg != new_ctrl)
                 rtc_write(rtc, OMAP_RTC_CTRL_REG, new_ctrl);
 
+        /*
+         * If we have the external clock then switch to it so we can keep
+         * ticking across 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);
 
         device_init_wakeup(&pdev->dev, true);
@@ -679,6 +695,7 @@ err:
 static int __exit omap_rtc_remove(struct platform_device *pdev)
 {
         struct omap_rtc *rtc = platform_get_drvdata(pdev);
+        u8 reg;
 
         if (pm_power_off == omap_rtc_power_off &&
                         omap_rtc_power_off_rtc == rtc) {
@@ -695,6 +712,12 @@ static int __exit omap_rtc_remove(struct platform_device *pdev)
         /* leave rtc running, but disable irqs */
         rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, 0);
 
+        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);
 
         /* Disable the clock/module */