Re: [PATCH v3 04/27] arm/MSI: Save MSI chip in pci_sys_data

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Wed, Oct 15, 2014 at 04:06:52AM +0100, Yijing Wang wrote:
> Saving msi chip in pci_sys_data can make pci bus and
> devices don't need to know msi chip detail, it also
> make pci enumeration code be decoupled from msi chip.
> In fact, all pci devices under the same pci hostbridge
> share same msi chip. So msi chip should be seen as one
> of resources or attributes to be initialized in pci host
> bridge driver. Currently, pci hostbridge drivers create
> pci_host_bridge in pci_create_root_bus(), and pass arch
> specific pci sysdata to core pci scan functions. So pci
> arch sysdata is good place to save msi chip.
>=20
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> ---
>  arch/arm/include/asm/mach/pci.h |    6 ++++++
>  arch/arm/include/asm/pci.h      |    9 +++++++++
>  arch/arm/kernel/bios32.c        |    3 +++
>  drivers/pci/msi.c               |    6 ++++++
>  include/linux/pci.h             |    9 +++++++++
>  5 files changed, 33 insertions(+), 0 deletions(-)
>=20
> diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/=
pci.h
> index 7fc4278..59b0d87 100644
> --- a/arch/arm/include/asm/mach/pci.h
> +++ b/arch/arm/include/asm/mach/pci.h
> @@ -22,6 +22,9 @@ struct hw_pci {
>  #ifdef CONFIG_PCI_DOMAINS
>  =09int=09=09domain;
>  #endif
> +#ifdef CONFIG_PCI_MSI
> +=09struct msi_chip *msi_chip;
> +#endif
>  =09struct pci_ops=09*ops;
>  =09int=09=09nr_controllers;
>  =09void=09=09**private_data;
> @@ -47,6 +50,9 @@ struct pci_sys_data {
>  #ifdef CONFIG_PCI_DOMAINS
>  =09int=09=09domain;
>  #endif
> +#ifdef CONFIG_PCI_MSI
> +=09struct msi_chip *msi_chip;
> +#endif

This struct is defined for ARM only. We are trying to remove dependency on =
it
so that we can have a single driver for ARM32 and ARM64 systems without
pcibios dependency. Why can't we add this msi chip data to the host
bridge struct instead ? I understand it is all a matter of how to pass
the pointer to pci_scan_root_bus(), where the bridge is created.
We could initialize the msi chip on the bridge through the bus pointer
returned by the pci_scan_root_bus() function.

Thanks,
Lorenzo

>  =09struct list_head node;
>  =09int=09=09busnr;=09=09/* primary bus number=09=09=09*/
>  =09u64=09=09mem_offset;=09/* bus->cpu memory mapping offset=09*/
> diff --git a/arch/arm/include/asm/pci.h b/arch/arm/include/asm/pci.h
> index 7e95d85..b562c09 100644
> --- a/arch/arm/include/asm/pci.h
> +++ b/arch/arm/include/asm/pci.h
> @@ -31,6 +31,15 @@ static inline int pci_proc_domain(struct pci_bus *bus)
>  }
>  #endif /* CONFIG_PCI_DOMAINS */
> =20
> +#ifdef CONFIG_PCI_MSI
> +static inline struct msi_chip *pci_msi_chip(struct pci_bus *bus)
> +{
> +=09struct pci_sys_data *root =3D bus->sysdata;
> +
> +=09return root->msi_chip;
> +}
> +#endif
> +
>  /*
>   * The PCI address space does equal the physical memory address space.
>   * The networking and block device layers use this boolean for bounce
> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
> index 17a26c1..a19038d 100644
> --- a/arch/arm/kernel/bios32.c
> +++ b/arch/arm/kernel/bios32.c
> @@ -471,6 +471,9 @@ static void pcibios_init_hw(struct device *parent, st=
ruct hw_pci *hw,
>  #ifdef CONFIG_PCI_DOMAINS
>  =09=09sys->domain  =3D hw->domain;
>  #endif
> +#ifdef CONFIG_PCI_MSI
> +=09=09sys->msi_chip =3D hw->msi_chip;
> +#endif
>  =09=09sys->busnr   =3D busnr;
>  =09=09sys->swizzle =3D hw->swizzle;
>  =09=09sys->map_irq =3D hw->map_irq;
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 22e413c..f11108c 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -35,6 +35,9 @@ int __weak arch_setup_msi_irq(struct pci_dev *dev, stru=
ct msi_desc *desc)
>  =09struct msi_chip *chip =3D dev->bus->msi;
>  =09int err;
> =20
> +=09if (!chip)
> +=09=09chip =3D pci_msi_chip(dev->bus);
> +
>  =09if (!chip || !chip->setup_irq)
>  =09=09return -EINVAL;
> =20
> @@ -50,6 +53,9 @@ void __weak arch_teardown_msi_irq(unsigned int irq)
>  =09struct msi_desc *entry =3D irq_get_msi_desc(irq);
>  =09struct msi_chip *chip =3D entry->dev->bus->msi;
> =20
> +=09if (!chip)
> +=09=09chip =3D pci_msi_chip(entry->dev->bus);
> +
>  =09if (!chip || !chip->teardown_irq)
>  =09=09return;
> =20
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 9cd2721..7a48b40 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1433,6 +1433,15 @@ static inline int pci_get_new_domain_nr(void) { re=
turn -ENOSYS; }
> =20
>  #include <asm/pci.h>
> =20
> +/* Just avoid compile error, will be clean up later */
> +#ifdef CONFIG_PCI_MSI
> +
> +#ifndef pci_msi_chip
> +#define pci_msi_chip(bus)=09NULL
> +#endif
> +
> +#endif
> +
>  /* these helpers provide future and backwards compatibility
>   * for accessing popular PCI BAR info */
>  #define pci_resource_start(dev, bar)=09((dev)->resource[(bar)].start)
> --=20
> 1.7.1
>=20
> --
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>=20