Date:   Mon, 7 Nov 2016 16:38:09 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Duc Dang <dhdang@....com>
Cc:     Rafael Wysocki <rafael@...nel.org>,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Mark Salter <msalter@...hat.com>, linux-pci@...r.kernel.org,
        linux-arm <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jon Masters <jcm@...hat.com>, Tomasz Nowicki <tn@...ihalf.com>,
        patches <patches@....com>
Subject: Re: [RFC PATCH v2 1/1] PCI/ACPI: xgene: Add ECAM quirk for X-Gene
 PCIe controller

On Wed, Nov 02, 2016 at 01:54:44PM -0700, Duc Dang wrote:
> On Wed, Nov 2, 2016 at 9:53 AM, Bjorn Helgaas <helgaas@...nel.org> wrote:
> > On Tue, Oct 25, 2016 at 06:24:32PM -0700, Duc Dang wrote:
> > > PCIe controllers in X-Gene SoCs is not ECAM compliant: software
> > > needs to configure additional controller's register to address
> > > device at bus:dev:function.
> > >
> > > This patch depends on "ECAM quirks handling for ARM64 platforms"
> > > series (http://www.spinics.net/lists/arm-kernel/msg530692.html,
> > > the series was also modified by Bjorn) to address the limitation
> > > above for X-Gene PCIe controller.
> > >
> > > The quirk will only be applied for X-Gene PCIe MCFG table with
> > > OEM revison 1, 2, 3 or 4 (PCIe controller v1 and v2 on X-Gene SoCs).
> >
> > The quirks here contain some hard-coded address space consumed by
> > ECAM.  The ECAM quirk itself is not a generic description of that
> > address space in the sense of a PCI BAR or an ACPI _CRS method, i.e.,
> > the quirk description is not enough to keep other parts of the kernel
> > from treating the address space as "available".
> 
> Your concern here is the controller register region that I declared as
> hard-coded array of resource (xgene_vx_csr_res) is not owned by the
> root bridge? So unlike DT case where kernel discovers and knows
> exactly who owns this resource (and we can also use
> platform_get_resource to get the resource); in ACPI case with ECAM
> quirk, kernel knows who requests this resource but does not know who
> owns it? Do I understand correctly?

I think so.  MCFG tells the PCI bridge driver where the ECAM space is.
But the ACPI core itself doesn't look at MCFG, so it doesn't know that
space is occupied, and it could potentially assign that space to some
other device, which would cause a conflict.

> > Can you add a note here in the changelog about how you are describing
> > this space generically?  The standard solution is a PNP0C02 device
> > with _CRS that describes it.
> >
> > It would be ideal if you could open a bugzilla at bugzilla.kernel.org
> > and attach there a dmesg log, /proc/iomem contents, and DSDT.  This
> > would show both the generic PNP0C02 piece and the ECAM quirk piece.
> 
> We don't have PNP0C02 device in our ACPI Table. Do you want me add a
> PNP0C02 device into our firmware and check/document the difference in
> /proc/iomem output?

Yes, you should have a PNP0C02 device and its _CRS should describe the
ECAM space.  _CRS is generic (not device-specific), and it's what
tells the ACPI core that the space is already in use.

If you already had a PNP0C02 device, you could make a quirk similar to
quirk_amd_mmconfig_area() to add things to its _CRS.

But I think you have firmware in the field that does not have a
PNP0C02 device at all, and that's harder to fix because you would need
to add some sort of fake device.

Rafael, do you have any ideas about this?  I can imagine something
like the following, but I don't know what cans of worms it might open:

  struct pnp_protocol pnpquirk_protocol = {
    .name = "Plug and Play Quirks",
  };

  void quirk()
  {
    struct pnp_dev *dev;
    struct resource res;

    ret = pnp_register_protocol(&pnpquirk_protocol);
    if (ret)
      return;

    dev = pnp_alloc_dev(&pnpquirk_protocol, 0, "PNP0C02");
    if (!dev)
      return;

    res.start = XX;          /* ECAM start */
    res.end = YY;            /* ECAM end */
    res.flags = IORESOURCE_MEM;
    pnp_add_resource(dev, &res);

    dev->active = 1;
    pnp_add_device(dev);

    dev_info(&dev->dev, "fabricated device to reserve ECAM space %pR\n", &res);
  }

> > BTW, I did refresh and re-push the pci/ecam-v6 branch where I'm
> > collecting this stuff, so if you want to rebase your patch on top of
> > that and test it, that would be great.
> 
> Thanks, I will definitely do that.
> >
> > > Signed-off-by: Duc Dang <dhdang@....com>
> > > ---
> > > v2 changes:
> > >       1. Get rid of pci-xgene-ecam.c file and fold quirk code into pci-xgene.c
> > >       2. Redefine fixup array for X-Gene
> > >       3. Use devm_ioremap_resource to map csr_base
> > >
> > >  drivers/acpi/pci_mcfg.c      |  30 ++++++++
> > >  drivers/pci/host/pci-xgene.c | 165 ++++++++++++++++++++++++++++++++++++++++++-
> > >  include/linux/pci-ecam.h     |   5 ++
> > >  3 files changed, 197 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
> > > index bb2c508..9dfc937 100644
> > > --- a/drivers/acpi/pci_mcfg.c
> > > +++ b/drivers/acpi/pci_mcfg.c
> > > @@ -96,6 +96,36 @@ struct mcfg_fixup {
> > >       THUNDER_ECAM_MCFG(2, 12),
> > >       THUNDER_ECAM_MCFG(2, 13),
> > >  #endif
> > > +#ifdef CONFIG_PCI_XGENE
> > > +#define XGENE_V1_ECAM_MCFG(rev, seg) \
> > > +     {"APM   ", "XGENE   ", rev, seg, MCFG_BUS_ANY, \
> > > +             &xgene_v1_pcie_ecam_ops }
> > > +#define XGENE_V2_1_ECAM_MCFG(rev, seg) \
> > > +     {"APM   ", "XGENE   ", rev, seg, MCFG_BUS_ANY, \
> > > +             &xgene_v2_1_pcie_ecam_ops }
> > > +#define XGENE_V2_2_ECAM_MCFG(rev, seg) \
> > > +     {"APM   ", "XGENE   ", rev, seg, MCFG_BUS_ANY, \
> > > +             &xgene_v2_2_pcie_ecam_ops }
> > > +
> > > +     /* X-Gene SoC with v1 PCIe controller */
> > > +     XGENE_V1_ECAM_MCFG(1, 0),
> > > +     XGENE_V1_ECAM_MCFG(1, 1),
> > > +     XGENE_V1_ECAM_MCFG(1, 2),
> > > +     XGENE_V1_ECAM_MCFG(1, 3),
> > > +     XGENE_V1_ECAM_MCFG(1, 4),
> > > +     XGENE_V1_ECAM_MCFG(2, 0),
> > > +     XGENE_V1_ECAM_MCFG(2, 1),
> > > +     XGENE_V1_ECAM_MCFG(2, 2),
> > > +     XGENE_V1_ECAM_MCFG(2, 3),
> > > +     XGENE_V1_ECAM_MCFG(2, 4),
> > > +     /* X-Gene SoC with v2.1 PCIe controller */
> > > +     XGENE_V2_1_ECAM_MCFG(3, 0),
> > > +     XGENE_V2_1_ECAM_MCFG(3, 1),
> > > +     /* X-Gene SoC with v2.2 PCIe controller */
> > > +     XGENE_V2_2_ECAM_MCFG(4, 0),
> > > +     XGENE_V2_2_ECAM_MCFG(4, 1),
> > > +     XGENE_V2_2_ECAM_MCFG(4, 2),
> > > +#endif
> > >  };
> > >
> > >  static char mcfg_oem_id[ACPI_OEM_ID_SIZE];
> > > diff --git a/drivers/pci/host/pci-xgene.c b/drivers/pci/host/pci-xgene.c
> > > index 1de23d7..d6aa642 100644
> > > --- a/drivers/pci/host/pci-xgene.c
> > > +++ b/drivers/pci/host/pci-xgene.c
> > > @@ -27,6 +27,8 @@
> > >  #include <linux/of_irq.h>
> > >  #include <linux/of_pci.h>
> > >  #include <linux/pci.h>
> > > +#include <linux/pci-acpi.h>
> > > +#include <linux/pci-ecam.h>
> > >  #include <linux/platform_device.h>
> > >  #include <linux/slab.h>
> > >
> > > @@ -64,6 +66,7 @@
> > >  /* PCIe IP version */
> > >  #define XGENE_PCIE_IP_VER_UNKN               0
> > >  #define XGENE_PCIE_IP_VER_1          1
> > > +#define XGENE_PCIE_IP_VER_2          2
> > >
> > >  struct xgene_pcie_port {
> > >       struct device_node      *node;
> > > @@ -97,7 +100,15 @@ static inline u32 pcie_bar_low_val(u32 addr, u32 flags)
> > >   */
> > >  static void __iomem *xgene_pcie_get_cfg_base(struct pci_bus *bus)
> > >  {
> > > -     struct xgene_pcie_port *port = bus->sysdata;
> > > +     struct pci_config_window *cfg;
> > > +     struct xgene_pcie_port *port;
> > > +
> > > +     if (acpi_disabled)
> > > +             port = bus->sysdata;
> > > +     else {
> > > +             cfg = bus->sysdata;
> > > +             port = cfg->priv;
> > > +     }
> > >
> > >       if (bus->number >= (bus->primary + 1))
> > >               return port->cfg_base + AXI_EP_CFG_ACCESS;
> > > @@ -111,10 +122,18 @@ static void __iomem *xgene_pcie_get_cfg_base(struct pci_bus *bus)
> > >   */
> > >  static void xgene_pcie_set_rtdid_reg(struct pci_bus *bus, uint devfn)
> > >  {
> > > -     struct xgene_pcie_port *port = bus->sysdata;
> > > +     struct pci_config_window *cfg;
> > > +     struct xgene_pcie_port *port;
> > >       unsigned int b, d, f;
> > >       u32 rtdid_val = 0;
> > >
> > > +     if (acpi_disabled)
> > > +             port = bus->sysdata;
> > > +     else {
> > > +             cfg = bus->sysdata;
> > > +             port = cfg->priv;
> > > +     }
> > > +
> > >       b = bus->number;
> > >       d = PCI_SLOT(devfn);
> > >       f = PCI_FUNC(devfn);
> > > @@ -158,7 +177,15 @@ static void __iomem *xgene_pcie_map_bus(struct pci_bus *bus, unsigned int devfn,
> > >  static int xgene_pcie_config_read32(struct pci_bus *bus, unsigned int devfn,
> > >                                   int where, int size, u32 *val)
> > >  {
> > > -     struct xgene_pcie_port *port = bus->sysdata;
> > > +     struct pci_config_window *cfg;
> > > +     struct xgene_pcie_port *port;
> > > +
> > > +     if (acpi_disabled)
> > > +             port = bus->sysdata;
> > > +     else {
> > > +             cfg = bus->sysdata;
> > > +             port = cfg->priv;
> > > +     }
> > >
> > >       if (pci_generic_config_read32(bus, devfn, where & ~0x3, 4, val) !=
> > >           PCIBIOS_SUCCESSFUL)
> > > @@ -189,6 +216,138 @@ static int xgene_pcie_config_read32(struct pci_bus *bus, unsigned int devfn,
> > >       .write = pci_generic_config_write32,
> > >  };
> > >
> > > +#ifdef CONFIG_ACPI
> > > +static struct resource xgene_v1_csr_res[] = {
> > > +     [0] = DEFINE_RES_MEM(0x1f2b0000UL, SZ_64K),
> > > +     [1] = DEFINE_RES_MEM(0x1f2c0000UL, SZ_64K),
> > > +     [2] = DEFINE_RES_MEM(0x1f2d0000UL, SZ_64K),
> > > +     [3] = DEFINE_RES_MEM(0x1f500000UL, SZ_64K),
> > > +     [4] = DEFINE_RES_MEM(0x1f510000UL, SZ_64K),
> > > +};
> > > +
> > > +static int xgene_v1_pcie_ecam_init(struct pci_config_window *cfg)
> > > +{
> > > +     struct acpi_device *adev = to_acpi_device(cfg->parent);
> > > +     struct acpi_pci_root *root = acpi_driver_data(adev);
> > > +     struct device *dev = cfg->parent;
> > > +     struct xgene_pcie_port *port;
> > > +     struct resource *csr;
> > > +
> > > +     port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
> > > +     if (!port)
> > > +             return -ENOMEM;
> > > +
> > > +     csr = &xgene_v1_csr_res[root->segment];
> > > +     port->csr_base = devm_ioremap_resource(dev, csr);
> > > +     if (IS_ERR(port->csr_base)) {
> > > +             kfree(port);
> > > +             return -ENOMEM;
> > > +     }
> > > +
> > > +     port->cfg_base = cfg->win;
> > > +     port->version = XGENE_PCIE_IP_VER_1;
> > > +
> > > +     cfg->priv = port;
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +struct pci_ecam_ops xgene_v1_pcie_ecam_ops = {
> > > +     .bus_shift      = 16,
> > > +     .init           = xgene_v1_pcie_ecam_init,
> > > +     .pci_ops        = {
> > > +             .map_bus        = xgene_pcie_map_bus,
> > > +             .read           = xgene_pcie_config_read32,
> > > +             .write          = pci_generic_config_write,
> > > +     }
> > > +};
> > > +
> > > +static struct resource xgene_v2_1_csr_res[] = {
> > > +     [0] = DEFINE_RES_MEM(0x1f2b0000UL, SZ_64K),
> > > +     [1] = DEFINE_RES_MEM(0x1f2c0000UL, SZ_64K),
> > > +};
> > > +
> > > +static int xgene_v2_1_pcie_ecam_init(struct pci_config_window *cfg)
> > > +{
> > > +     struct acpi_device *adev = to_acpi_device(cfg->parent);
> > > +     struct acpi_pci_root *root = acpi_driver_data(adev);
> > > +     struct device *dev = cfg->parent;
> > > +     struct xgene_pcie_port *port;
> > > +     struct resource *csr;
> > > +
> > > +     port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
> > > +     if (!port)
> > > +             return -ENOMEM;
> > > +
> > > +     csr = &xgene_v2_1_csr_res[root->segment];
> > > +     port->csr_base = devm_ioremap_resource(dev, csr);
> > > +     if (IS_ERR(port->csr_base)) {
> > > +             kfree(port);
> > > +             return -ENOMEM;
> > > +     }
> > > +
> > > +     port->cfg_base = cfg->win;
> > > +     port->version = XGENE_PCIE_IP_VER_2;
> > > +
> > > +     cfg->priv = port;
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +struct pci_ecam_ops xgene_v2_1_pcie_ecam_ops = {
> > > +     .bus_shift      = 16,
> > > +     .init           = xgene_v2_1_pcie_ecam_init,
> > > +     .pci_ops        = {
> > > +             .map_bus        = xgene_pcie_map_bus,
> > > +             .read           = xgene_pcie_config_read32,
> > > +             .write          = pci_generic_config_write,
> > > +     }
> > > +};
> > > +
> > > +static struct resource xgene_v2_2_csr_res[] = {
> > > +     [0] = DEFINE_RES_MEM(0x1f2b0000UL, SZ_64K),
> > > +     [1] = DEFINE_RES_MEM(0x1f500000UL, SZ_64K),
> > > +     [2] = DEFINE_RES_MEM(0x1f2d0000UL, SZ_64K),
> > > +};
> > > +
> > > +static int xgene_v2_2_pcie_ecam_init(struct pci_config_window *cfg)
> > > +{
> > > +     struct acpi_device *adev = to_acpi_device(cfg->parent);
> > > +     struct acpi_pci_root *root = acpi_driver_data(adev);
> > > +     struct device *dev = cfg->parent;
> > > +     struct xgene_pcie_port *port;
> > > +     struct resource *csr;
> > > +
> > > +     port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
> > > +     if (!port)
> > > +             return -ENOMEM;
> > > +
> > > +     csr = &xgene_v2_2_csr_res[root->segment];
> > > +     port->csr_base = devm_ioremap_resource(dev, csr);
> > > +     if (IS_ERR(port->csr_base)) {
> > > +             kfree(port);
> > > +             return -ENOMEM;
> > > +     }
> > > +
> > > +     port->cfg_base = cfg->win;
> > > +     port->version = XGENE_PCIE_IP_VER_2;
> > > +
> > > +     cfg->priv = port;
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +struct pci_ecam_ops xgene_v2_2_pcie_ecam_ops = {
> > > +     .bus_shift      = 16,
> > > +     .init           = xgene_v2_2_pcie_ecam_init,
> > > +     .pci_ops        = {
> > > +             .map_bus        = xgene_pcie_map_bus,
> > > +             .read           = xgene_pcie_config_read32,
> > > +             .write          = pci_generic_config_write,
> > > +     }
> > > +};
> > > +#endif
> > > +
> > >  static u64 xgene_pcie_set_ib_mask(struct xgene_pcie_port *port, u32 addr,
> > >                                 u32 flags, u64 size)
> > >  {
> > > diff --git a/include/linux/pci-ecam.h b/include/linux/pci-ecam.h
> > > index 35f0e81..40da3e7 100644
> > > --- a/include/linux/pci-ecam.h
> > > +++ b/include/linux/pci-ecam.h
> > > @@ -65,6 +65,11 @@ void __iomem *pci_ecam_map_bus(struct pci_bus *bus, unsigned int devfn,
> > >  #ifdef CONFIG_PCI_HOST_THUNDER_ECAM
> > >  extern struct pci_ecam_ops pci_thunder_ecam_ops;
> > >  #endif
> > > +#ifdef CONFIG_PCI_XGENE
> > > +extern struct pci_ecam_ops xgene_v1_pcie_ecam_ops;
> > > +extern struct pci_ecam_ops xgene_v2_1_pcie_ecam_ops;
> > > +extern struct pci_ecam_ops xgene_v2_2_pcie_ecam_ops;
> > > +#endif
> > >
> > >  #ifdef CONFIG_PCI_HOST_GENERIC
> > >  /* for DT-based PCI controllers that support ECAM */
> > > --
> > > 1.9.1
> > >
> Regards,
> Duc Dang.

Powered by blists - more mailing lists