linux-kernel - Re: [PATCH V3 2/4] ARM64 LPC: LPC driver implementation on Hip06

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Message-ID: <1849232.KJrfRPHGN6@wuerfel>
Date:   Fri, 23 Sep 2016 17:55:10 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Gabriele Paoloni <gabriele.paoloni@...wei.com>
Cc:     "zhichang.yuan" <zhichang.yuan02@...il.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "minyard@....org" <minyard@....org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        John Garry <john.garry@...wei.com>,
        "will.deacon@....com" <will.deacon@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Yuanzhichang <yuanzhichang@...ilicon.com>,
        Linuxarm <linuxarm@...wei.com>,
        "xuwei (O)" <xuwei5@...ilicon.com>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "zourongrong@...il.com" <zourongrong@...il.com>,
        "liviu.dudau@....com" <liviu.dudau@....com>,
        "kantyzc@....com" <kantyzc@....com>
Subject: Re: [PATCH V3 2/4] ARM64 LPC: LPC driver implementation on Hip06

On Friday, September 23, 2016 2:59:55 PM CEST Gabriele Paoloni wrote:
> 
> > > From the perspective of the indirect IO function the input parameter
> > > is an unsigned long addr that (now) can be either:
> > > 1) an IO token coming from a legacy pci device
> > > 2) a phys address that lives on the LPC bus
> > >
> > > These are conceptually two separate address spaces (and actually they
> > > both start from 0).
> > 
> > Why? Any IORESOURCE_IO address always refers to the logical I/O port
> > range in Linux, not the physical address that is used on a bus.
> 
> If I read the code correctly when you get an I/O token you just add it
> to PCI_IOBASE.
> This is enough since pci_remap_iospace set the virtual address to 
> PCI_IOBASE + the I/O token offset; so we can read/write to
> vaddr = PCI_IOBASE + token as pci_remap_iospace has mapped it correctly
> to the respective PCI cpu address (that is set in the I/O range property
> of the host controller)
> 
> In the patchset accessors LPC operates directly on the cpu addresses
> and the input parameter of the accessors can be either an IO token or
> a cpu address
> 
> +static inline void outb(u8 value, unsigned long addr)
> +{
> +#ifdef CONFIG_ARM64_INDIRECT_PIO
> +       if (arm64_extio_ops && arm64_extio_ops->start <= addr &&
> +                       addr <= arm64_extio_ops->end)
> 
> Here below we operate on cpu address
> 
> +               extio_outb(value, addr);
> +       else
> +#endif

I missed this bug earlier, this obviously needs to be

		arm64_extio_ops->outb(value, addr - arm64_extio_ops->start);

or possibly

		arm64_extio_ops->outb(arm64_extio_ops, value, addr);

as the outb function won't know what the offset is, but
that needed to be fixed regardless.

	Arnd