linux-kernel - RE: [PATCH v10 1/6] drivers/platform/x86/p2sb: New Primary to Sideband bridge support driver for Intel SOC's

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Message-ID: <0158A29DB680F54A88142ED28D55B1D008329343@PGSMSX107.gar.corp.intel.com>
Date:   Fri, 9 Dec 2016 07:50:48 +0000
From:   "Tan, Jui Nee" <jui.nee.tan@...el.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "heikki.krogerus@...ux.intel.com" <heikki.krogerus@...ux.intel.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "dvhart@...radead.org" <dvhart@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
        "ptyser@...-inc.com" <ptyser@...-inc.com>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Yong, Jonathan" <jonathan.yong@...el.com>,
        "Yu, Ong Hock" <ong.hock.yu@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Wan Mohamad, Wan Ahmad Zainie" 
        <wan.ahmad.zainie.wan.mohamad@...el.com>,
        "Sun, Yunying" <yunying.sun@...el.com>
Subject: RE: [PATCH v10 1/6] drivers/platform/x86/p2sb: New Primary to
 Sideband bridge support driver for Intel SOC's



> -----Original Message-----
> From: linux-gpio-owner@...r.kernel.org [mailto:linux-gpio-
> owner@...r.kernel.org] On Behalf Of Andy Shevchenko
> Sent: Friday, November 11, 2016 12:07 AM
> To: Tan, Jui Nee <jui.nee.tan@...el.com>; mika.westerberg@...ux.intel.com;
> heikki.krogerus@...ux.intel.com; tglx@...utronix.de; dvhart@...radead.org;
> mingo@...hat.com; hpa@...or.com; x86@...nel.org; ptyser@...-inc.com;
> lee.jones@...aro.org; linus.walleij@...aro.org
> Cc: linux-gpio@...r.kernel.org; platform-driver-x86@...r.kernel.org;
> linux-kernel@...r.kernel.org; Yong, Jonathan <jonathan.yong@...el.com>;
> Yu, Ong Hock <ong.hock.yu@...el.com>; Luck, Tony <tony.luck@...el.com>;
> Wan Mohamad, Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@...el.com>;
> Sun, Yunying <yunying.sun@...el.com>
> Subject: Re: [PATCH v10 1/6] drivers/platform/x86/p2sb: New Primary to
> Sideband bridge support driver for Intel SOC's
> 
> On Thu, 2016-11-10 at 17:00 +0800, Tan Jui Nee wrote:
> > From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> >
> > There is already one and at least one more user coming which require
> > an access to Primary to Sideband bridge (P2SB) in order to get IO or
> > MMIO bar hidden by BIOS.
> > Create a driver to access P2SB for x86 devices.
> >
> > Signed-off-by: Yong, Jonathan <jonathan.yong@...el.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> 
> 
> > +int p2sb_bar(struct pci_dev *pdev, unsigned int devfn,
> > +	struct resource *res)
> > +{
> > +	u32 base_addr;
> > +	u64 base64_addr;
> > +	unsigned long flags;
> > +
> >
> 
> > +	if (!res)
> > +		return -EINVAL;
> 
> I don't remember the details, one version was quite changed, so, I think
> these lines are not needed anymore.
> 
Noted, these lines will be removed in next patch version (v12).
> > +	/* Get IO or MMIO BAR */
> > +	pci_bus_read_config_dword(pdev->bus, devfn, SBREG_BAR,
> > &base_addr);
> > +	if ((base_addr & PCI_BASE_ADDRESS_SPACE) ==
> > PCI_BASE_ADDRESS_SPACE_IO) {
> > +		flags = IORESOURCE_IO;
> > +		base64_addr = base_addr & PCI_BASE_ADDRESS_IO_MASK;
> > +	} else {
> > +		flags = IORESOURCE_MEM;
> > +		base64_addr = base_addr & PCI_BASE_ADDRESS_MEM_MASK;
> > +		if (base_addr & PCI_BASE_ADDRESS_MEM_TYPE_64) {
> > +			flags |= IORESOURCE_MEM_64;
> >
> 
> > +			pci_bus_read_config_dword(pdev->bus, devfn,
> > +				SBREG_BAR + 4, &base_addr);
> 
> Fix indentation.
> 
Thanks for pointing that out. I will fix that in next patch version (v12). 
> > +			base64_addr |= (u64)base_addr << 32;
> > +		}
> > +	}
> > +
> > +	/* Hide the P2SB device */
> > +	pci_bus_write_config_byte(pdev->bus, devfn, SBREG_HIDE,
> > 0x01);
> > +
> > +	spin_unlock(&p2sb_spinlock);
> > +
> 
> > +	/* User provides prefilled resources */
> 
> Not anymore as far I as I can see. You just return here the result.
> 
Current version is returning status of p2sb_bar function, i.e., 0 on success or appropriate errno value on error. Perhaps you could share the reason of return the result instead of status. 
> > +	res->start = (resource_size_t)base64_addr;
> > +	res->flags = flags;
> 
> --
> Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Intel Finland Oy
> --
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