Re: [PATCH v8 2/4] rtc: goldfish: introduce goldfish_ioread32()/goldfish_iowrite32()

[Jiaxun Yang]

在2022年1月15日一月 下午7:32，Laurent Vivier写道：
> The goldfish device always uses the same endianness as the architecture
> using it:
> https://android.googlesource.com/platform/external/qemu/+/refs/heads/emu-master-dev/hw/timer/goldfish_timer.c#177
>
> On a big-endian machine, the device is also big-endian, on a
> little-endian machine the device is little-endian.
>
> So we need to use the right accessor to read/write values to the goldfish
> registers: ioread32()/iowrite32() on a little-endian machine,
> ioread32be()/iowrite32be() on a big-endian machine.
>
> This patch introduces goldfish_ioread32()/goldfish_iowrite32() that uses
> the expected accessor according to the machine endianness.
>
> Signed-off-by: Laurent Vivier <laurent@xxxxxxxxx>

Acked-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>

> ---
>  drivers/rtc/rtc-goldfish.c | 39 +++++++++++++++++++++++---------------
>  1 file changed, 24 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/rtc/rtc-goldfish.c b/drivers/rtc/rtc-goldfish.c
> index 7ab95d052644..b0cae4729b03 100644
> --- a/drivers/rtc/rtc-goldfish.c
> +++ b/drivers/rtc/rtc-goldfish.c
> @@ -23,6 +23,15 @@
>  #define TIMER_ALARM_STATUS	0x18
>  #define TIMER_CLEAR_INTERRUPT	0x1c
> 
> +/* goldfish endianness depends on CPU endianness */
> +#ifdef CONFIG_CPU_BIG_ENDIAN
> +#define goldfish_ioread32 ioread32be
> +#define goldfish_iowrite32 iowrite32be
> +#else
> +#define goldfish_ioread32 ioread32
> +#define goldfish_iowrite32 iowrite32
> +#endif
> +
>  struct goldfish_rtc {
>  	void __iomem *base;
>  	int irq;
> @@ -41,8 +50,8 @@ static int goldfish_rtc_read_alarm(struct device *dev,
>  	rtcdrv = dev_get_drvdata(dev);
>  	base = rtcdrv->base;
> 
> -	rtc_alarm_low = readl(base + TIMER_ALARM_LOW);
> -	rtc_alarm_high = readl(base + TIMER_ALARM_HIGH);
> +	rtc_alarm_low = goldfish_ioread32(base + TIMER_ALARM_LOW);
> +	rtc_alarm_high = goldfish_ioread32(base + TIMER_ALARM_HIGH);
>  	rtc_alarm = (rtc_alarm_high << 32) | rtc_alarm_low;
> 
>  	do_div(rtc_alarm, NSEC_PER_SEC);
> @@ -50,7 +59,7 @@ static int goldfish_rtc_read_alarm(struct device *dev,
> 
>  	rtc_time64_to_tm(rtc_alarm, &alrm->time);
> 
> -	if (readl(base + TIMER_ALARM_STATUS))
> +	if (goldfish_ioread32(base + TIMER_ALARM_STATUS))
>  		alrm->enabled = 1;
>  	else
>  		alrm->enabled = 0;
> @@ -71,18 +80,18 @@ static int goldfish_rtc_set_alarm(struct device *dev,
> 
>  	if (alrm->enabled) {
>  		rtc_alarm64 = rtc_tm_to_time64(&alrm->time) * NSEC_PER_SEC;
> -		writel((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
> -		writel(rtc_alarm64, base + TIMER_ALARM_LOW);
> -		writel(1, base + TIMER_IRQ_ENABLED);
> +		goldfish_iowrite32((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
> +		goldfish_iowrite32(rtc_alarm64, base + TIMER_ALARM_LOW);
> +		goldfish_iowrite32(1, base + TIMER_IRQ_ENABLED);
>  	} else {
>  		/*
>  		 * if this function was called with enabled=0
>  		 * then it could mean that the application is
>  		 * trying to cancel an ongoing alarm
>  		 */
> -		rtc_status_reg = readl(base + TIMER_ALARM_STATUS);
> +		rtc_status_reg = goldfish_ioread32(base + TIMER_ALARM_STATUS);
>  		if (rtc_status_reg)
> -			writel(1, base + TIMER_CLEAR_ALARM);
> +			goldfish_iowrite32(1, base + TIMER_CLEAR_ALARM);
>  	}
> 
>  	return 0;
> @@ -98,9 +107,9 @@ static int goldfish_rtc_alarm_irq_enable(struct device *dev,
>  	base = rtcdrv->base;
> 
>  	if (enabled)
> -		writel(1, base + TIMER_IRQ_ENABLED);
> +		goldfish_iowrite32(1, base + TIMER_IRQ_ENABLED);
>  	else
> -		writel(0, base + TIMER_IRQ_ENABLED);
> +		goldfish_iowrite32(0, base + TIMER_IRQ_ENABLED);
> 
>  	return 0;
>  }
> @@ -110,7 +119,7 @@ static irqreturn_t goldfish_rtc_interrupt(int irq, 
> void *dev_id)
>  	struct goldfish_rtc *rtcdrv = dev_id;
>  	void __iomem *base = rtcdrv->base;
> 
> -	writel(1, base + TIMER_CLEAR_INTERRUPT);
> +	goldfish_iowrite32(1, base + TIMER_CLEAR_INTERRUPT);
> 
>  	rtc_update_irq(rtcdrv->rtc, 1, RTC_IRQF | RTC_AF);
> 
> @@ -128,8 +137,8 @@ static int goldfish_rtc_read_time(struct device 
> *dev, struct rtc_time *tm)
>  	rtcdrv = dev_get_drvdata(dev);
>  	base = rtcdrv->base;
> 
> -	time_low = readl(base + TIMER_TIME_LOW);
> -	time_high = readl(base + TIMER_TIME_HIGH);
> +	time_low = goldfish_ioread32(base + TIMER_TIME_LOW);
> +	time_high = goldfish_ioread32(base + TIMER_TIME_HIGH);
>  	time = (time_high << 32) | time_low;
> 
>  	do_div(time, NSEC_PER_SEC);
> @@ -149,8 +158,8 @@ static int goldfish_rtc_set_time(struct device 
> *dev, struct rtc_time *tm)
>  	base = rtcdrv->base;
> 
>  	now64 = rtc_tm_to_time64(tm) * NSEC_PER_SEC;
> -	writel((now64 >> 32), base + TIMER_TIME_HIGH);
> -	writel(now64, base + TIMER_TIME_LOW);
> +	goldfish_iowrite32((now64 >> 32), base + TIMER_TIME_HIGH);
> +	goldfish_iowrite32(now64, base + TIMER_TIME_LOW);
> 
>  	return 0;
>  }
> -- 
> 2.34.1

-- 
- Jiaxun