From: Keerthy <a0393675@ti.com>
To: Andrew Morton <akpm@linux-foundation.org>, <rtc-linux@googlegroups.com>
Cc: Keerthy <j-keerthy@ti.com>, <a.zummo@towertech.it>,
<linux-kernel@vger.kernel.org>, <linux-omap@vger.kernel.org>
Subject: Re: [rtc-linux] [PATCH] rtc: OMAP: Add external 32k clock feature
Date: Tue, 7 Apr 2015 08:59:41 +0530 [thread overview]
Message-ID: <55234F25.5060708@ti.com> (raw)
In-Reply-To: <20150324155916.cfd1b7ab442271466160283f@linux-foundation.org>
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-keerthy@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
next prev parent reply other threads:[~2015-04-07 3:30 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-03 9:42 [PATCH] rtc: OMAP: Add external 32k clock feature Keerthy
2015-03-17 4:15 ` Keerthy
2015-03-24 22:59 ` [rtc-linux] " Andrew Morton
2015-04-07 3:29 ` Keerthy [this message]
2015-04-07 7:06 ` Igor Grinberg
2015-04-10 8:26 ` Keerthy
2015-04-10 20:37 ` Andrew Morton
2015-04-10 22:23 ` Alexandre Belloni
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