linux-kernel - Re: [PATCH v2 3/3] mfd: add CSR SiRFSoC on-chip power management module driver

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Date:	Tue, 29 Sep 2015 16:30:52 +0800
From:	Barry Song <21cnbao@...il.com>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	Mark Brown <broonie@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	sameo <sameo@...ux.intel.com>,
	LKML <linux-kernel@...r.kernel.org>,
	DL-SHA-WorkGroupLinux <workgroup.linux@....com>,
	Guo Zeng <Guo.Zeng@....com>, Barry Song <Baohua.Song@....com>
Subject: Re: [PATCH v2 3/3] mfd: add CSR SiRFSoC on-chip power management
 module driver

2015-09-29 15:16 GMT+08:00 Lee Jones <lee.jones@...aro.org>:
> On Tue, 29 Sep 2015, Barry Song wrote:
>> >> >> +static int sirfsoc_pwrc_probe(struct platform_device *pdev)
>> >> >> +{
>> >> >> +     struct device_node *np = pdev->dev.of_node;
>> >> >> +     const struct of_device_id *match;
>> >> >> +     struct sirfsoc_pwrc_info *pwrcinfo;
>> >> >> +     struct regmap_irq_chip *regmap_irq_chip;
>> >> >> +     struct sirfsoc_pwrc_register *pwrc_reg;
>> >> >> +     struct regmap *map;
>> >> >> +     int ret;
>> >> >> +     u32 base;
>> >> >> +
>> >> >> +     if (of_property_read_u32(np, "reg", &base))
>> >> >> +             panic("unable to find base address of pwrc node in dtb\n");
>> >> >
>> >> > It looks like this driver should depend on OF.
>> >> >
>> >> > Why are you obtaining the base address manually? Use:
>> >> >
>> >> >   res = platform_get_resource();
>> >> >   devm_ioremap_resource(res);
>> >> >
>> >> > ... instead.
>> >>
>> >> this was explained as they are not in memory space, they are behind a
>> >> bus bridge.
>> >
>> > Use 'ranges' in the DT, then you can pull out the proper address
>> > without hand rolling your own method.
>>
>> it seems it is not a "ranges" thing,  things behind rtciobrg is much
>> like things behind USB or sdio. we need to use a rtciobrg protocol to
>> do read/write.
>> they can not be randomly accessed by load/store, and can't be XIP.
>> they don't have any ranges in CPU memory space.
>
> So what's the point of 'base' then?  I assumed this was the base of
> the IP registers which where memory mapped?

just think we have a i2c device, and this i2c device has multi-functions.
each function has a base of its register offset.
actually, the base is the offset of 1st register.


-barry
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