From: Keerthy <j-keerthy@ti.com>
To: <alexandre.belloni@free-electrons.com>
Cc: <a.zummo@towertech.it>, <rtc-linux@googlegroups.com>,
<linux-omap@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<lokeshvutla@ti.com>, <j-keerthy@ti.com>, <t-kristo@ti.com>
Subject: [PATCH 1/2] rtc: omap: Fix selecting external osc
Date: Thu, 27 Oct 2016 11:27:25 +0530 [thread overview]
Message-ID: <1477547846-5335-1-git-send-email-j-keerthy@ti.com> (raw)
From: Lokesh Vutla <lokeshvutla@ti.com>
RTC can be clocked from an external 32KHz oscillator, or from the
Peripheral PLL. The RTC has an internal oscillator buffer to support
direct operation with a crystal.
----------------------------------------
| Device --------- |
| | | |
| | RTCSS | |
| --------- | | |
OSC |<------| RTC | | | |
|------>| OSC |--- | | |
| -------- | | | |
| ----|clk | |
| -------- | | | |
| | PRCM |--- | | |
| -------- -------- |
----------------------------------------
The RTC functional clock is sourced by default from the clock derived
from the Peripheral PLL. In order to select source as external osc clk
the following changes needs to be done:
- Enable the RTC OSC (RTC_OSC_REG[4]OSC32K_GZ = 0)
- Enable the clock mux(RTC_OSC_REG[6]K32CLK_EN = 1)
- Select the external clock source (RTC_OSC_REG[3]32KCLK_SEL = 1)
Fixes: 399cf0f63f6f2 ("rtc: omap: Add external clock enabling support")
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
---
Boot tested and checked for rtc ticking on am335x-boneblack, am335x-bone
am437x-gp-evm, dra7-evm, dra72-evm.
drivers/rtc/rtc-omap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index b04ea9b..dddaa60 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -113,6 +113,7 @@
/* OMAP_RTC_OSC_REG bit fields: */
#define OMAP_RTC_OSC_32KCLK_EN BIT(6)
#define OMAP_RTC_OSC_SEL_32KCLK_SRC BIT(3)
+#define OMAP_RTC_OSC_OSC32K_GZ_DISABLE BIT(4)
/* OMAP_RTC_IRQWAKEEN bit fields: */
#define OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN BIT(1)
@@ -786,8 +787,9 @@ static int omap_rtc_probe(struct platform_device *pdev)
*/
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);
+ reg &= ~OMAP_RTC_OSC_OSC32K_GZ_DISABLE;
+ reg |= OMAP_RTC_OSC_32KCLK_EN | OMAP_RTC_OSC_SEL_32KCLK_SRC;
+ rtc_writel(rtc, OMAP_RTC_OSC_REG, reg);
}
rtc->type->lock(rtc);
--
1.9.1
next reply other threads:[~2016-10-27 5:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-27 5:57 Keerthy [this message]
2016-10-27 5:57 ` [PATCH 2/2] rtc: omap: prevent disabling of clock/module during suspend Keerthy
2016-11-05 2:35 ` [PATCH 1/2] rtc: omap: Fix selecting external osc Alexandre Belloni
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