linux-kernel - Re: [PATCH 08/11] PCI: mvebu: Use child

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Message-ID: <CAL_Jsq+1hoAUVOzyOGZ1vVMsChhHJJpzk5HNU4Gi=Luy_8LArA@mail.gmail.com>
Date:   Wed, 5 Jan 2022 09:41:51 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Pali Rohár <pali@...nel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Marek Behún <kabel@...nel.org>,
        Russell King <rmk+kernel@...linux.org.uk>,
        PCI <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 08/11] PCI: mvebu: Use child_ops API

On Wed, Jan 5, 2022 at 9:03 AM Pali Rohár <pali@...nel.org> wrote:
>
> Split struct pci_ops between ops and child_ops. Member ops is used for
> accessing PCIe Root Ports via pci-bridge-emul.c driver and child_ops for
> accessing real PCIe cards.
>
> There is no need to mix these two struct pci_ops into one as PCI core code
> already provides separate callbacks via bridge->ops and bridge->child_ops.

I had similar patches including mvebu that I never got around to
sending out. I pushed the branch out now at least[1].

> Signed-off-by: Pali Rohár <pali@...nel.org>
> ---
>  drivers/pci/controller/pci-mvebu.c | 82 ++++++++++++++++--------------
>  1 file changed, 44 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
> index 9ea2f6a7c2b0..1e90ab888075 100644
> --- a/drivers/pci/controller/pci-mvebu.c
> +++ b/drivers/pci/controller/pci-mvebu.c
> @@ -294,11 +294,29 @@ static void mvebu_pcie_setup_hw(struct mvebu_pcie_port *port)
>         mvebu_writel(port, mask, PCIE_MASK_OFF);
>  }
>
> -static int mvebu_pcie_hw_rd_conf(struct mvebu_pcie_port *port,
> -                                struct pci_bus *bus,
> -                                u32 devfn, int where, int size, u32 *val)
> +static struct mvebu_pcie_port *mvebu_pcie_find_port(struct mvebu_pcie *pcie,
> +                                                   struct pci_bus *bus,
> +                                                   int devfn);
> +
> +static int mvebu_pcie_child_rd_conf(struct pci_bus *bus, u32 devfn, int where,
> +                                   int size, u32 *val)
>  {
> -       void __iomem *conf_data = port->base + PCIE_CONF_DATA_OFF;
> +       struct mvebu_pcie *pcie = bus->sysdata;
> +       struct mvebu_pcie_port *port;
> +       void __iomem *conf_data;
> +
> +       port = mvebu_pcie_find_port(pcie, bus, devfn);
> +       if (!port) {
> +               *val = 0xffffffff;
> +               return PCIBIOS_DEVICE_NOT_FOUND;
> +       }
> +
> +       if (!mvebu_pcie_link_up(port)) {
> +               *val = 0xffffffff;
> +               return PCIBIOS_DEVICE_NOT_FOUND;
> +       }
> +
> +       conf_data = port->base + PCIE_CONF_DATA_OFF;
>
>         mvebu_writel(port, PCIE_CONF_ADDR(bus->number, devfn, where),
>                      PCIE_CONF_ADDR_OFF);
> @@ -321,11 +339,21 @@ static int mvebu_pcie_hw_rd_conf(struct mvebu_pcie_port *port,
>         return PCIBIOS_SUCCESSFUL;
>  }
>
> -static int mvebu_pcie_hw_wr_conf(struct mvebu_pcie_port *port,
> -                                struct pci_bus *bus,
> -                                u32 devfn, int where, int size, u32 val)
> +static int mvebu_pcie_child_wr_conf(struct pci_bus *bus, u32 devfn,
> +                                   int where, int size, u32 val)
>  {
> -       void __iomem *conf_data = port->base + PCIE_CONF_DATA_OFF;
> +       struct mvebu_pcie *pcie = bus->sysdata;
> +       struct mvebu_pcie_port *port;
> +       void __iomem *conf_data;
> +
> +       port = mvebu_pcie_find_port(pcie, bus, devfn);
> +       if (!port)
> +               return PCIBIOS_DEVICE_NOT_FOUND;
> +
> +       if (!mvebu_pcie_link_up(port))
> +               return PCIBIOS_DEVICE_NOT_FOUND;
> +
> +       conf_data = port->base + PCIE_CONF_DATA_OFF;

The same code in read and write is a hint to use .map_bus().

>
>         mvebu_writel(port, PCIE_CONF_ADDR(bus->number, devfn, where),
>                      PCIE_CONF_ADDR_OFF);
> @@ -347,6 +375,11 @@ static int mvebu_pcie_hw_wr_conf(struct mvebu_pcie_port *port,
>         return PCIBIOS_SUCCESSFUL;
>  }
>
> +static struct pci_ops mvebu_pcie_child_ops = {
> +       .read = mvebu_pcie_child_rd_conf,
> +       .write = mvebu_pcie_child_wr_conf,
> +};
> +
>  /*
>   * Remove windows, starting from the largest ones to the smallest
>   * ones.
> @@ -862,25 +895,12 @@ static int mvebu_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
>  {
>         struct mvebu_pcie *pcie = bus->sysdata;
>         struct mvebu_pcie_port *port;
> -       int ret;
>
>         port = mvebu_pcie_find_port(pcie, bus, devfn);
>         if (!port)
>                 return PCIBIOS_DEVICE_NOT_FOUND;

It would be nice to go from 'bus' to 'bridge' ptr directly, but I
still had this in my version. I guess a standard RP struct as part of
decoupling host bridges from RPs would solve this issue.

Rob

[1] https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/log/?h=pci-child-bus-ops