linux-kernel - Re: [PATCH 3/3] drivers/rtc/rtc-snvs: Add clock support

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Date:	Sun, 28 Sep 2014 11:56:33 +0800
From:	Shawn Guo <shawn.guo@...escale.com>
To:	Sanchayan Maity <maitysanchayan@...il.com>
CC:	<kernel@...gutronix.de>, <a.zummo@...ertech.it>,
	<b35083@...escale.com>, <rtc-linux@...glegroups.com>,
	<stefan@...er.ch>, <linux@....linux.org.uk>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] drivers/rtc/rtc-snvs: Add clock support

On Fri, Sep 26, 2014 at 06:44:01PM +0530, Sanchayan Maity wrote:
> This patch adds clock enable and disable support
> for the SNVS peripheral which is required by the
> SNVS RTC.
> 
> Signed-off-by: Sanchayan Maity <maitysanchayan@...il.com>
> ---
>  drivers/rtc/rtc-snvs.c |   48 +++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 39 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
> index fa384fe..f3e8f05 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)
> @@ -260,8 +262,31 @@ static int snvs_rtc_probe(struct platform_device *pdev)
>  	if (data->irq < 0)
>  		return data->irq;
>  
> +	ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
> +			       IRQF_SHARED, "rtc alarm", &pdev->dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to request irq %d: %d\n",
> +			data->irq, ret);
> +		return ret;
> +	}
> +
> +	data->clk = devm_clk_get(&pdev->dev, "snvs");
> +	if (IS_ERR(data->clk)) {
> +		dev_err(&pdev->dev, "failed getting clock, err = %ld\n",
> +						PTR_ERR(data->clk));
> +		ret = PTR_ERR(data->clk);
> +		return ret;
> +	}

No. This will break all i.MX6 devices running a DTB without clock
definition.

Shawn

> +
>  	platform_set_drvdata(pdev, data);
>  
> +	ret = clk_prepare_enable(data->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"Could not prepare or enable the snvs clock\n");
> +		return ret;
> +	}
> +
>  	spin_lock_init(&data->lock);
>  
>  	/* Initialize glitch detect */
> @@ -275,23 +300,20 @@ static int snvs_rtc_probe(struct platform_device *pdev)
>  
>  	device_init_wakeup(&pdev->dev, true);
>  
> -	ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
> -			       IRQF_SHARED, "rtc alarm", &pdev->dev);
> -	if (ret) {
> -		dev_err(&pdev->dev, "failed to request irq %d: %d\n",
> -			data->irq, ret);
> -		return ret;
> -	}
> -
>  	data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
>  					&snvs_rtc_ops, THIS_MODULE);
>  	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:
> +	clk_disable_unprepare(data->clk);
> +
> +	return ret;
>  }
>  
>  #ifdef CONFIG_PM_SLEEP
> @@ -302,16 +324,24 @@ static int snvs_rtc_suspend(struct device *dev)
>  	if (device_may_wakeup(dev))
>  		enable_irq_wake(data->irq);
>  
> +	clk_disable_unprepare(data->clk);
> +
>  	return 0;
>  }
>  
>  static int snvs_rtc_resume(struct device *dev)
>  {
> +	int ret;
> +
>  	struct snvs_rtc_data *data = dev_get_drvdata(dev);
>  
>  	if (device_may_wakeup(dev))
>  		disable_irq_wake(data->irq);
>  
> +	ret = clk_prepare_enable(data->clk);
> +	if (ret)
> +		return ret;
> +
>  	return 0;
>  }
>  #endif
> -- 
> 1.7.9.5
> 
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