linux-kernel - Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

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Date:	Thu, 04 Dec 2014 10:36:55 +0100
From:	Stefan Agner <stefan@...er.ch>
To:	Sanchayan Maity <maitysanchayan@...il.com>
Cc:	a.zummo@...ertech.it, rtc-linux@...glegroups.com,
	shawn.guo@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

On 2014-12-03 06:58, Sanchayan Maity wrote:
> This patch adds clock enable and disable support for
> the SNVS peripheral, which is required for using the
> RTC within the SNVS block.
> 
> The clock is not strictly enforced, as this would
> break the i.MX devices. The clocking for the i.MX
> devices seems to be enabled elsewhere and enabling
> RTC SNVS for Vybrid results in a crash. This patch
> adds the clock support but also makes it optional
> so Vybrid platform can use the clock if defined
> while making sure not to break i.MX .
> 
> Signed-off-by: Sanchayan Maity <maitysanchayan@...il.com>
> ---
>  drivers/rtc/rtc-snvs.c |   34 ++++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
> index fa384fe..d4a6512 100644
> --- a/drivers/rtc/rtc-snvs.c
> +++ b/drivers/rtc/rtc-snvs.c
> @@ -17,6 +17,7 @@
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  #include <linux/rtc.h>
> +#include <linux/clk.h>
>  
>  /* These register offsets are relative to LP (Low Power) range */
>  #define SNVS_LPCR		0x04
> @@ -39,6 +40,7 @@ struct snvs_rtc_data {
>  	void __iomem *ioaddr;
>  	int irq;
>  	spinlock_t lock;
> +	struct clk *clk;
>  };
>  
>  static u32 rtc_read_lp_counter(void __iomem *ioaddr)
> @@ -260,6 +262,18 @@ static int snvs_rtc_probe(struct platform_device *pdev)
>  	if (data->irq < 0)
>  		return data->irq;
>  
> +	data->clk = devm_clk_get(&pdev->dev, "snvs-rtc");
> +	if (IS_ERR(data->clk)) {
> +		data->clk = NULL;
> +	} else {
> +		ret = clk_prepare_enable(data->clk);
> +		if (ret) {
> +			dev_err(&pdev->dev,
> +				"Could not prepare or enable the snvs clock\n");
> +			return ret;
> +		}
> +	}
> +
>  	platform_set_drvdata(pdev, data);
>  
>  	spin_lock_init(&data->lock);
> @@ -280,7 +294,7 @@ static int snvs_rtc_probe(struct platform_device *pdev)
>  	if (ret) {
>  		dev_err(&pdev->dev, "failed to request irq %d: %d\n",
>  			data->irq, ret);
> -		return ret;
> +		goto error_rtc_device_register;
>  	}
>  
>  	data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
> @@ -288,10 +302,16 @@ static int snvs_rtc_probe(struct platform_device *pdev)
>  	if (IS_ERR(data->rtc)) {
>  		ret = PTR_ERR(data->rtc);
>  		dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
> -		return ret;
> +		goto error_rtc_device_register;
>  	}
>  
>  	return 0;
> +
> +error_rtc_device_register:
> +	if (data->clk)
> +		clk_disable_unprepare(data->clk);
> +
> +	return ret;
>  }
>  
>  #ifdef CONFIG_PM_SLEEP
> @@ -302,16 +322,26 @@ static int snvs_rtc_suspend(struct device *dev)
>  	if (device_may_wakeup(dev))
>  		enable_irq_wake(data->irq);
>  
> +	if (data->clk)
> +		clk_disable_unprepare(data->clk);
> +
>  	return 0;
>  }
>  
>  static int snvs_rtc_resume(struct device *dev)
>  {
>  	struct snvs_rtc_data *data = dev_get_drvdata(dev);
> +	int ret;
>  
>  	if (device_may_wakeup(dev))
>  		disable_irq_wake(data->irq);
>  
> +	if (data->clk) {
> +		ret = clk_prepare_enable(data->clk);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	return 0;
>  }
>  #endif


Acked-by: Stefan Agner <stefan@...er.ch>

--
Stefan

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