Hi Andrew,

Apologies for replying late.

On Wednesday 25 March 2015 04:29 AM, Andrew Morton wrote:
On Tue, 3 Mar 2015 15:12:02 +0530 Keerthy <j-keer...@ti.com> wrote:

Add external 32k clock feature. The internal clock will be gated during suspend.
Hence make use of the external 32k clock so that rtc is functional accross
suspend/resume.

...

@@ -446,6 +449,7 @@ static const struct omap_rtc_device_type 
omap_rtc_default_type = {

  static const struct omap_rtc_device_type omap_rtc_am3352_type = {
        .has_32kclk_en  = true,
+       .has_osc_ext_32k = true,
        .has_kicker     = true,
        .has_irqwakeen  = true,
        .has_pmic_mode  = true,
@@ -543,7 +547,16 @@ static int __init omap_rtc_probe(struct platform_device 
*pdev)
        if (rtc->type->has_32kclk_en) {
                reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
                rtc_writel(rtc, OMAP_RTC_OSC_REG,
-                               reg | OMAP_RTC_OSC_32KCLK_EN);
+                          reg | OMAP_RTC_OSC_32KCLK_EN);
+       }
+
+       /* Enable External clock as the source */
+
+       if (rtc->type->has_osc_ext_32k) {
+               rtc_writel(rtc, OMAP_RTC_OSC_REG,
+                          (OMAP_RTC_OSC_EXT_32K |
+                          rtc_read(rtc, OMAP_RTC_OSC_REG)) &
+                          (~OMAP_RTC_OSC_OSC32K_GZ));
        }

How do we know that all systems have this external clock and that it
works OK?


AM335 and AM43X have the external clock feature which we choose using RTC_OSC_REG. I verified it works OK by seeing the RTC seconds ticking even after switching the source to the external 32k Clock.

Regards,
Keerthy
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