linux-kernel - RE: [RFC PATCH 00/11] Refactor MSI to support Non-PCI device

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Date:	Wed, 20 Aug 2014 07:41:55 +0000
From:	"Bharat.Bhushan@...escale.com" <Bharat.Bhushan@...escale.com>
To:	Yijing Wang <wangyijing@...wei.com>,
	"arnab.basu@...escale.com" <arnab.basu@...escale.com>
CC:	Xinwei Hu <huxinwei@...wei.com>, Wuyun <wuyun.wu@...wei.com>,
	"Bjorn Helgaas" <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"Paul.Mundt@...wei.com" <Paul.Mundt@...wei.com>,
	"James E.J. Bottomley" <jejb@...isc-linux.org>,
	Marc Zyngier <marc.zyngier@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Russell King <linux@....linux.org.uk>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	"virtualization@...ts.linux-foundation.org" 
	<virtualization@...ts.linux-foundation.org>,
	Hanjun Guo <guohanjun@...wei.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [RFC PATCH 00/11] Refactor MSI to support Non-PCI device



> -----Original Message-----
> From: linux-pci-owner@...r.kernel.org [mailto:linux-pci-owner@...r.kernel.org]
> On Behalf Of Yijing Wang
> Sent: Wednesday, August 20, 2014 11:59 AM
> To: Bhushan Bharat-R65777; Basu Arnab-B45036
> Cc: Xinwei Hu; Wuyun; Bjorn Helgaas; linux-pci@...r.kernel.org;
> Paul.Mundt@...wei.com; James E.J. Bottomley; Marc Zyngier; linux-arm-
> kernel@...ts.infradead.org; Russell King; linux-arch@...r.kernel.org;
> virtualization@...ts.linux-foundation.org; Hanjun Guo; linux-
> kernel@...r.kernel.org
> Subject: Re: [RFC PATCH 00/11] Refactor MSI to support Non-PCI device
> 
> >> The key difference between PCI device and Non-PCI MSI is the
> >> interfaces to access hardware MSI registers.
> >> for instance, currently, msi_chip->setup_irq() to setup MSI irq and
> >> configure the MSI address/data registers, so we need to provide
> >> device specific
> >> write_msi_msg() interface, then when we call msi_chip->setup_irq(),
> >> the device MSI registers can be configured appropriately.
> >
> > What if we can register/override the setup_irq() from bus-driver (not sure,
> but may be device-driver itself). Example PCI bus-driver will provide
> setup_irq() (or the part of setup_irq which set address and data in h/w) by PCI
> bus, which configure address/data in h/w as per PCI standard.
> >
> > We in Freescale will be using MSI for the devices behind a new-bus (which is
> not PCI based), We have a separate bus driver for same. And this new bus driver
> register/provide its own address/data write function which is based on that
> specific bus protocol.
> 
> Hi Bharat, I'm glad to know your MSI device working mode.
> Provide the private MSI setup functions in bus-driver layer can't apply to all
> Non-PCI MSI devices, because we can not guarantee Non-PCI MSI devices are always
> on a bus. The existing HPET, DMAR device both have no bus bind.

Yes, that's why I was not sure of bus-driver or device-driver model.

> I'm working on a
> new MSI setup framework, as you mentioned before, in device-driver model.
> 
> I abstracted a new virtual device (called struct msi_dev), this msi_dev will
> manage all MSI info,

Will this "struct msi_dev" will be part of "struct device"?

> and a new bus named msi_bus, also introduced a new driver
> msi_driver, msi_bus is responsible for binding msi_dev and msi_driver.
> All MSI devices will be classified into different MSI device types, like
> MSI_TYPE_PCI, MSI_TYPE_HPET, MSI_TYPE_DMAR, etc..
> 
> Each MSI type device should provide a private struct msi_driver. msi_driver
> should contain the type specific MSI ops functions to help setup and enable MSI
> device, request MSI irq.
> 
> I almost finish the first draft, and will post out next week in plan :)

Will be looking forward to next version.

Thanks
-Bharat

> 
> 
> Thanks!
> Yijing.
> 
> >
> > Thanks
> > -Bharat
> >
> >>
> >> My patchset is just a RFC draft, I will update it later, all we want
> >> to do is make kernel support Non-PCI MSI devices.
> >>
> >> Thanks!
> >> Yijing.
> >>
> >>
> >>>
> >>> Thanks
> >>> Arnab
> >>> --
> >>> To unsubscribe from this list: send the line "unsubscribe
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> >>> Please read the FAQ at  http://www.tux.org/lkml/
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> >>> .
> >>>
> >>
> >>
> >> --
> >> Thanks!
> >> Yijing
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-pci"
> >> in the body of a message to majordomo@...r.kernel.org More majordomo
> >> info at http://vger.kernel.org/majordomo-info.html
> >
> > .
> >
> 
> 
> --
> Thanks!
> Yijing
> 
> --
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