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

[Lee Jones]

On Tue, 29 Sep 2015, Barry Song wrote:

> 2015-09-29 15:16 GMT+08:00 Lee Jones <lee.jones@xxxxxxxxxx>:
> > 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.

Does it every change, from device to device?

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org â Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/