linux-kernel - Re: [PATCH v3 35/36] platform/x86: intel_pmc

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Message-ID: <20200120111312.GD15507@dell>
Date:   Mon, 20 Jan 2020 11:13:12 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Darren Hart <dvhart@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Zha Qipeng <qipeng.zha@...el.com>,
        "David E . Box" <david.e.box@...ux.intel.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 35/36] platform/x86: intel_pmc_ipc: Convert to MFD

> Adding Mark (the Regmap Maintainer) to the conversation.

Fingers faster than brain!

I'll actually add him this time - sorry for the noise!

> On Mon, 20 Jan 2020, Mika Westerberg wrote:
> > On Fri, Jan 17, 2020 at 11:32:02AM +0000, Lee Jones wrote:
> > > [...]
> > > 
> > > > > Looks like Regmap could save you the trouble here.
> > > > 
> > > > Agreed.
> > > 
> > > Great.
> > 
> > I started to implement regmap for this driver but I run into some
> > problems. The registers we read/write are all 64-bit and accessed trough
> > readq/writeq accessors. However, the regmap API takes unsigned int:
> > 
> >   int regmap_write(struct regmap *map, unsigned int reg, unsigned int val);
> >   int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val);
> > 
> > I'm not sure how we can take advantage of this API with the 64-bit
> > registers. There are "raw" versions of the functions that take void
> > pointer like:
> > 
> >  int regmap_raw_read(struct regmap *map, unsigned int reg,
> >                      void *val, size_t val_len);
> > 
> > but looking at the implementation if the register gets cached it
> > internally does reads in unsigned int sized chunks (if I understand it
> > right).
> > 
> > Any ideas how this can be done?
 
Mark,

  Does Regmap support 64bit accesses?

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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