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From: "Li.Xiubo@freescale.com" <Li.Xiubo@freescale.com>
To: Thomas Gleixner <tglx@linutronix.de>
CC: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
        "Dongsheng.Wang@freescale.com" <Dongsheng.Wang@freescale.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 2/5] Clocksource: Flextimer: Use internal clocksource read
 API.
Thread-Topic: [PATCH 2/5] Clocksource: Flextimer: Use internal clocksource
 read API.
Thread-Index: AQHPwPGfS8nkeT6FCkuUDVIJ9Bh425vvRJOAgAD90OCAAHITAIAAANvg
Date: Thu, 4 Sep 2014 08:43:28 +0000
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> >
> > Since the FTM will be in BE mode on LS1 platform, but will be in LE mode
> > On LS2 platform.
> >
> > And ftm_clocksource_read_up() will adapt to this different.
> 
> You are missing the point. Why do you want a conditional in a hot
> path? You know at init time whether the thing is BE or LE, so you can
> have separate functions for BE/LE or whatever and register that with
> clocksource_mmio_init(). i.e.
> 
>      if (be)
>      	clocksource_mmio_init(....., cs_read_be);
>      else if (le)
>      	clocksource_mmio_init(....., cs_read_le);
>      else if (magic)
>      	clocksource_mmio_init(....., cs_read_magic);
> 

There already has the following access interfaces:

static inline u32 ftm_readl(void __iomem *addr)
{
        if (priv->big_endian)
                return ioread32be(addr);
        else
                return ioread32(addr);
}

static inline void ftm_writel(u32 val, void __iomem *addr)
{
        if (priv->big_endian)
                iowrite32be(val, addr);
        else
                iowrite32(val, addr);
}

So I added the following code:

static cycle_t ftm_clocksource_read_up(struct clocksource *c)
{
        return ftm_readl(priv->clksrc_base + FTM_CNT) & 0xffff;
}

clocksource_mmio_init(.....,ftm_clocksource_read_up);

Is this okay ?

Thanks,

BRs
Xiubo