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

[Simon Baatz]

Hi Andrew,

On Sun, Feb 03, 2013 at 11:30:53AM +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 at lunn.ch>
> ---
>  arch/arm/boot/dts/kirkwood.dtsi |    1 +
>  drivers/rtc/rtc-mv.c            |   15 ++++++++++++++-
>  2 files changed, 15 insertions(+), 1 deletion(-)
> 
> 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..365bc83 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)
> @@ -260,6 +262,11 @@ static int mv_rtc_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, pdata);
>  
> +	pdata->clk = devm_clk_get(&pdev->dev, NULL);
> +	/* Not all SoCs require a clock.*/
> +	if (!IS_ERR(pdata->clk))
> +		clk_prepare_enable(pdata->clk);
> +

There are already I/O accesses to the RTC above this. Thus, you
probably need to move this up.


- Simon