linux-kernel - Re: [PATCH 03/12] rtc: omap: fix class-device registration

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Date:	Fri, 10 Oct 2014 12:59:30 -0500
From:	Felipe Balbi <balbi@...com>
To:	Johan Hovold <johan@...nel.org>
CC:	Alessandro Zummo <a.zummo@...ertech.it>,
	Tony Lindgren <tony@...mide.com>,
	Benoît Cousson <bcousson@...libre.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Felipe Balbi <balbi@...com>, Lokesh Vutla <lokeshvutla@...com>,
	Guenter Roeck <linux@...ck-us.net>,
	Colin Foe-Parker <colin.foeparker@...icpd.com>,
	<nsekhar@...com>, <t-kristo@...com>, <j-keerthy@...com>,
	<linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<devicetree@...r.kernel.org>, <rtc-linux@...glegroups.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/12] rtc: omap: fix class-device registration

On Thu, Oct 09, 2014 at 09:06:25PM +0200, Johan Hovold wrote:
> Make sure not to register the class device until after it has been
> configured and interrupt handlers registered at probe.
> 
> Currently, the device is not fully configured (e.g. 24-hour mode) when
> the class device is registered, something which involves driver
> callbacks for example to read the current time.
> 
> This reordering also prevents user space from enabling an alarm before
> an interrupt handler has been registered.
> 
> Note that the interrupts are now registered using the platform-device
> rather than class-device name.
> 
> Signed-off-by: Johan Hovold <johan@...nel.org>
> ---
>  drivers/rtc/rtc-omap.c | 32 +++++++++++++++++---------------
>  1 file changed, 17 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 828cb9983cc2..2eca141e784e 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -147,8 +147,9 @@ static void rtc_wait_not_busy(void)
>  	/* now we have ~15 usec to read/write various registers */
>  }
>  
> -static irqreturn_t rtc_irq(int irq, void *rtc)
> +static irqreturn_t rtc_irq(int irq, void *dev_id)
>  {
> +	struct rtc_device	*rtc = platform_get_drvdata(dev_id);
>  	unsigned long		events = 0;
>  	u8			irq_data;
>  
> @@ -164,7 +165,8 @@ static irqreturn_t rtc_irq(int irq, void *rtc)
>  	if (irq_data & OMAP_RTC_STATUS_1S_EVENT)
>  		events |= RTC_IRQF | RTC_UF;
>  
> -	rtc_update_irq(rtc, 1, events);
> +	if (rtc)
> +		rtc_update_irq(rtc, 1, events);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -416,17 +418,6 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
>  		rtc_writel(KICK1_VALUE, OMAP_RTC_KICK1_REG);
>  	}
>  
> -	device_init_wakeup(&pdev->dev, true);
> -
> -	rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
> -			&omap_rtc_ops, THIS_MODULE);
> -	if (IS_ERR(rtc)) {
> -		pr_debug("%s: can't register RTC device, err %ld\n",
> -			pdev->name, PTR_ERR(rtc));
> -		goto fail0;
> -	}
> -	platform_set_drvdata(pdev, rtc);
> -
>  	/* clear pending irqs, and set 1/second periodic,
>  	 * which we'll use instead of update irqs
>  	 */
> @@ -450,14 +441,14 @@ static int __init omap_rtc_probe(struct platform_device *pdev)
>  
>  	/* handle periodic and alarm irqs */
>  	if (devm_request_irq(&pdev->dev, omap_rtc_timer, rtc_irq, 0,
> -			dev_name(&rtc->dev), rtc)) {
> +			dev_name(&pdev->dev), pdev)) {
>  		pr_debug("%s: RTC timer interrupt IRQ%d already claimed\n",
>  			pdev->name, omap_rtc_timer);
>  		goto fail0;
>  	}
>  	if ((omap_rtc_timer != omap_rtc_alarm) &&
>  		(devm_request_irq(&pdev->dev, omap_rtc_alarm, rtc_irq, 0,
> -			dev_name(&rtc->dev), rtc))) {
> +			dev_name(&pdev->dev), pdev))) {

i don't get it. Why pass pdev as cookie when all you need is rtc ?
Doesn't sound very good to me. Also, IRQ handler *must* be registered
only after RTC is registered. That's because if you request an IRQ here,
you could already have a pending interrupt and since you won't have a
valid rtc pointer you won't be able to clear the interrupt line.

-- 
balbi

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