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SubjectRe: [rtc-linux] [PATCH 2/2] rtc: mediatek: Add MT63xx RTC driver
From
Date
Hi,

On Mon, 2015-02-23 at 13:50 -0800, Andrew Morton wrote:
> On Wed, 28 Jan 2015 17:27:56 +0800 Eddie Huang <eddie.huang@mediatek.com> wrote:
>
> > From: Tianping Fang <tianping.fang@mediatek.com>
> >
> > Add Mediatek MT63xx RTC driver
>
> There are a couple of checkpatch warnings which should be addressed,
> please:
>
> WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> #150:
> new file mode 100644
>
> WARNING: DT compatible string "mediatek,mt6397-rtc" appears un-documented -- check ./Documentation/devicetree/bindings/
> #488: FILE: drivers/rtc/rtc-mt6397.c:334:
> + { .compatible = "mediatek,mt6397-rtc", },
>
>
>
>
> >
> > ...
> >
> > +static u16 rtc_read(struct mt6397_rtc *rtc, u32 offset)
> > +{
> > + u32 rdata = 0;
> > + u32 addr = rtc->addr_base + offset;
> > +
> > + if (offset < rtc->addr_range)
> > + regmap_read(rtc->regmap, addr, &rdata);
> > +
> > + return (u16)rdata;
> > +}
> > +
> > +static void rtc_write(struct mt6397_rtc *rtc, u32 offset, u32 data)
> > +{
> > + u32 addr;
> > +
> > + addr = rtc->addr_base + offset;
> > +
> > + if (offset < rtc->addr_range)
> > + regmap_write(rtc->regmap, addr, data);
> > +}
>
> regmap_read() and regmap_write() can return errors. There is no
> checking for this.
>

I encounter some trouble when I add code to check return value of
regmap_read and regmap_write. Every RTC register access through regmap,
and there are many register read/write in this driver. If I check every
return value, the driver will become ugly. I try to make this driver
clean using following macro.

static int __rtc_read(struct mt6397_rtc *rtc, u32 offset, u32 *data)
{
u32 addr = rtc->addr_base + offset;

if (offset < rtc->addr_range)
return regmap_read(rtc->regmap, addr, data);

return -EINVAL;
}

#define rtc_read(ret, rtc, offset, data) \
({ \
ret = __rtc_read(rtc, offset, data); \
if (ret < 0) \
goto rtc_exit; \
}) \


And function call rtc_read, rtc_write looks like:

static int mtk_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
unsigned long time;
struct mt6397_rtc *rtc = dev_get_drvdata(dev);
int ret = 0;
u32 sec;

mutex_lock(&rtc->lock);
do {
rtc_read(ret, rtc, RTC_TC_SEC, &tm->tm_sec);
rtc_read(ret, rtc, RTC_TC_MIN, &tm->tm_min);
rtc_read(ret, rtc, RTC_TC_HOU, &tm->tm_hour);
rtc_read(ret, rtc, RTC_TC_DOM, &tm->tm_mday);
rtc_read(ret, rtc, RTC_TC_MTH, &tm->tm_mon);
rtc_read(ret, rtc, RTC_TC_YEA, &tm->tm_year);
rtc_read(ret, rtc, RTC_TC_SEC, &sec);
} while (sec < tm->tm_sec);
mutex_unlock(&rtc->lock);

tm->tm_year += RTC_MIN_YEAR_OFFSET;
tm->tm_mon--;
rtc_tm_to_time(tm, &time);

tm->tm_wday = (time / 86400 + 4) % 7;

return 0;

rtc_exit:
mutex_unlock(&rtc->lock);
return ret;
}

It's a little tricky, does anyone have good suggestion ?

Eddie






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