[PATCH v2] rtc: rtc-mv: Add support for clk to avoid lockups

[PATCH v2] rtc: rtc-mv: Add support for clk to avoid lockups

[Andrew Lunn]

The Marvell RTC on Kirkwood makes use of the runit clock. Ensure the
driver clk_prepare_enable() this clock, otherwise there is a danger
the SoC will lockup when accessing RTC registers with the clock
disabled.

Reported-by: Simon Baatz gmbnomis at gmail.com
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---

Since v1:
Enable clock before accessing RTC registers.

 arch/arm/boot/dts/kirkwood.dtsi |    1 +
 drivers/rtc/rtc-mv.c            |   28 ++++++++++++++++++++++++----
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/arch/arm/boot/dts/kirkwood.dtsi b/arch/arm/boot/dts/kirkwood.dtsi
index 6c5d75f..c57b9c6 100644
--- a/arch/arm/boot/dts/kirkwood.dtsi
+++ b/arch/arm/boot/dts/kirkwood.dtsi
@@ -77,6 +77,7 @@
 			compatible = "marvell,kirkwood-rtc", "marvell,orion-rtc";
 			reg = <0x10300 0x20>;
 			interrupts = <53>;
+			clocks = <&gate_clk 7>;
 		};
 
 		spi at 10600 {
diff --git a/drivers/rtc/rtc-mv.c b/drivers/rtc/rtc-mv.c
index 57233c8..8f87fec 100644
--- a/drivers/rtc/rtc-mv.c
+++ b/drivers/rtc/rtc-mv.c
@@ -14,6 +14,7 @@
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/delay.h>
+#include <linux/clk.h>
 #include <linux/gfp.h>
 #include <linux/module.h>
 
@@ -41,6 +42,7 @@ struct rtc_plat_data {
 	struct rtc_device *rtc;
 	void __iomem *ioaddr;
 	int		irq;
+	struct clk	*clk;
 };
 
 static int mv_rtc_set_time(struct device *dev, struct rtc_time *tm)
@@ -221,6 +223,7 @@ static int mv_rtc_probe(struct platform_device *pdev)
 	struct rtc_plat_data *pdata;
 	resource_size_t size;
 	u32 rtc_time;
+	int ret = 0;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res)
@@ -239,11 +242,17 @@ static int mv_rtc_probe(struct platform_device *pdev)
 	if (!pdata->ioaddr)
 		return -ENOMEM;
 
+	pdata->clk = devm_clk_get(&pdev->dev, NULL);
+	/* Not all SoCs require a clock.*/
+	if (!IS_ERR(pdata->clk))
+		clk_prepare_enable(pdata->clk);
+
 	/* make sure the 24 hours mode is enabled */
 	rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
 	if (rtc_time & RTC_HOURS_12H_MODE) {
 		dev_err(&pdev->dev, "24 Hours mode not supported.\n");
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 
 	/* make sure it is actually functional */
@@ -252,7 +261,8 @@ static int mv_rtc_probe(struct platform_device *pdev)
 		rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
 		if (rtc_time == 0x01000000) {
 			dev_err(&pdev->dev, "internal RTC not ticking\n");
-			return -ENODEV;
+			ret = -ENODEV;
+			goto out;
 		}
 	}
 
@@ -268,8 +278,10 @@ static int mv_rtc_probe(struct platform_device *pdev)
 	} else
 		pdata->rtc = rtc_device_register(pdev->name, &pdev->dev,
 						 &mv_rtc_ops, THIS_MODULE);
-	if (IS_ERR(pdata->rtc))
-		return PTR_ERR(pdata->rtc);
+	if (IS_ERR(pdata->rtc)) {
+		ret = PTR_ERR(pdata->rtc);
+		goto out;
+	}
 
 	if (pdata->irq >= 0) {
 		writel(0, pdata->ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
@@ -282,6 +294,11 @@ static int mv_rtc_probe(struct platform_device *pdev)
 	}
 
 	return 0;
+out:
+	if (!IS_ERR(pdata->clk))
+		clk_disable_unprepare(pdata->clk);
+
+	return ret;
 }
 
 static int __exit mv_rtc_remove(struct platform_device *pdev)
@@ -292,6 +309,9 @@ static int __exit mv_rtc_remove(struct platform_device *pdev)
 		device_init_wakeup(&pdev->dev, 0);
 
 	rtc_device_unregister(pdata->rtc);
+	if (!IS_ERR(pdata->clk))
+		clk_disable_unprepare(pdata->clk);
+
 	return 0;
 }
 
-- 
1.7.10.4

[PATCH v2] rtc: rtc-mv: Add support for clk to avoid lockups

[Simon Baatz]

Hi Andrew,

On Sun, Feb 03, 2013 at 12:32:06PM +0100, Andrew Lunn wrote:
> The Marvell RTC on Kirkwood makes use of the runit clock. Ensure the
> driver clk_prepare_enable() this clock, otherwise there is a danger
> the SoC will lockup when accessing RTC registers with the clock
> disabled.
> 
> Reported-by: Simon Baatz gmbnomis at gmail.com
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>

And:

Tested-by: Simon Baatz <gmbnomis@gmail.com>

Btw, <...> is missing from the email address in the Reported-by line.

Thanks for providing this so quickly. Now, it looks like this
(without applying the GPIO fix, yet, because it would already enable
the runit clock):

# cat /sys/kernel/debug/clk/tclk/runit/clk_enable_count
0
# insmod ./rtc-mv.ko
# cat /sys/kernel/debug/clk/tclk/runit/clk_enable_count
1
# hwclock
Sun Feb  3 19:34:53 2013  -1.003522 seconds
# rmmod rtc-mv
# cat /sys/kernel/debug/clk/tclk/runit/clk_enable_count
0


- Simon

[PATCH v2] rtc: rtc-mv: Add support for clk to avoid lockups

[Jason Cooper]

On Sun, Feb 03, 2013 at 08:44:07PM +0100, Simon Baatz wrote:
> Hi Andrew,
> 
> On Sun, Feb 03, 2013 at 12:32:06PM +0100, Andrew Lunn wrote:
> > The Marvell RTC on Kirkwood makes use of the runit clock. Ensure the
> > driver clk_prepare_enable() this clock, otherwise there is a danger
> > the SoC will lockup when accessing RTC registers with the clock
> > disabled.
> > 
> > Reported-by: Simon Baatz gmbnomis at gmail.com
> > Signed-off-by: Andrew Lunn <andrew@lunn.ch>
> 
> And:
> 
> Tested-by: Simon Baatz <gmbnomis@gmail.com>
> 
> Btw, <...> is missing from the email address in the Reported-by line.

I'll clean that up.  no need for a new version.

> Thanks for providing this so quickly. Now, it looks like this
> (without applying the GPIO fix, yet, because it would already enable
> the runit clock):
> 
> # cat /sys/kernel/debug/clk/tclk/runit/clk_enable_count
> 0
> # insmod ./rtc-mv.ko
> # cat /sys/kernel/debug/clk/tclk/runit/clk_enable_count
> 1
> # hwclock
> Sun Feb  3 19:34:53 2013  -1.003522 seconds
> # rmmod rtc-mv
> # cat /sys/kernel/debug/clk/tclk/runit/clk_enable_count
> 0

Great!  Thanks for turning around those tests so quickly.

thx,

Jason.

[PATCH v2] rtc: rtc-mv: Add support for clk to avoid lockups

[Jason Cooper]

On Sun, Feb 03, 2013 at 12:32:06PM +0100, Andrew Lunn wrote:
> The Marvell RTC on Kirkwood makes use of the runit clock. Ensure the
> driver clk_prepare_enable() this clock, otherwise there is a danger
> the SoC will lockup when accessing RTC registers with the clock
> disabled.
> 
> Reported-by: Simon Baatz gmbnomis at gmail.com
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>
> ---
> 
> Since v1:
> Enable clock before accessing RTC registers.
> 
>  arch/arm/boot/dts/kirkwood.dtsi |    1 +
>  drivers/rtc/rtc-mv.c            |   28 ++++++++++++++++++++++++----
>  2 files changed, 25 insertions(+), 4 deletions(-)

Applied to mvebu/fixes with Simon's Tested-by: and added '<' '>' to the
Reported-by:.

thx,

Jason.