[PATCH 3.16.y-ckt 118/216] rtc: omap: fix clock-source configuration

[Luis Henriques]

3.16.7-ckt4 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan at kernel.org>

commit 44c63a570aaec3c5d5569d63b7c4a31ddd88cae0 upstream.

This series fixes a few issues with the omap rtc-driver, cleans up a
bit, adds device abstraction, and finally adds support for the PMIC
control feature found in some revisions of this RTC IP block.

Ultimately, this allows for powering off the Beaglebone and waking it up
again on RTC alarms.

This patch (of 20):

Make sure not to reset the clock-source configuration when enabling the
32kHz clock mux.

Until the clock source can be configured through device tree we must not
overwrite settings made by the bootloader (e.g.  clock-source
selection).

Fixes: cd914bba03d8 ("drivers/rtc/rtc-omap.c: add support for enabling 32khz clock")
Signed-off-by: Johan Hovold <johan at kernel.org>
Reviewed-by: Felipe Balbi <balbi at ti.com>
Tested-by: Felipe Balbi <balbi at ti.com>
Cc: Alessandro Zummo <a.zummo at towertech.it>
Cc: Tony Lindgren <tony at atomide.com>
Cc: Benot Cousson <bcousson at baylibre.com>
Cc: Lokesh Vutla <lokeshvutla at ti.com>
Cc: Guenter Roeck <linux at roeck-us.net>
Cc: Sekhar Nori <nsekhar at ti.com>
Cc: Tero Kristo <t-kristo at ti.com>
Cc: Keerthy J <j-keerthy at ti.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 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 21142e6574a9..f842c216f2dd 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -431,8 +431,10 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
 	rtc_write(0, OMAP_RTC_INTERRUPTS_REG);
 
 	/* enable RTC functional clock */
-	if (id_entry->driver_data & OMAP_RTC_HAS_32KCLK_EN)
-		rtc_writel(OMAP_RTC_OSC_32KCLK_EN, OMAP_RTC_OSC_REG);
+	if (id_entry->driver_data & OMAP_RTC_HAS_32KCLK_EN) {
+		reg = rtc_read(OMAP_RTC_OSC_REG);
+		rtc_writel(reg | OMAP_RTC_OSC_32KCLK_EN, OMAP_RTC_OSC_REG);
+	}
 
 	/* clear old status */
 	reg = rtc_read(OMAP_RTC_STATUS_REG);
-- 
2.1.4