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Message-ID: <1480620053.4751.30.camel@redhat.com>
Date: Thu, 01 Dec 2016 14:20:53 -0500
From: Mark Salter <msalter@...hat.com>
To: Bjorn Helgaas <helgaas@...nel.org>, Duc Dang <dhdang@....com>
Cc: Rafael Wysocki <rafael@...nel.org>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
Arnd Bergmann <arnd@...db.de>, 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: [PATCH v3] PCI/ACPI: xgene: Add ECAM quirk for X-Gene PCIe
controller
On Thu, 2016-12-01 at 12:33 -0600, Bjorn Helgaas wrote:
> Hi Duc,
>
> On Wed, Nov 30, 2016 at 03:42:53PM -0800, 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.
> >
> > 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 quirk declares the X-Gene PCIe controller register space as 64KB
> > fixed memory resource with name "PCIe CSR". This name will be showed
> > next to the resource range in the output of "cat /proc/iomem".
> >
> > Signed-off-by: Duc Dang <dhdang@....com>
> > ---
> > v3:
> > - Rebase on top of pci/ecam-v6 tree.
> > - Use DEFINE_RES_MEM_NAMED to declare controller register space
> > with name "PCIe CSR"
> > v2:
> > RFC v2: https://patchwork.ozlabs.org/patch/686846/
> > v1:
> > RFC v1: https://patchwork.kernel.org/patch/9337115/
> >
> > drivers/acpi/pci_mcfg.c | 31 ++++++++
> > drivers/pci/host/pci-xgene.c | 165 ++++++++++++++++++++++++++++++++++++++++++-
> > include/linux/pci-ecam.h | 7 ++
> > 3 files changed, 200 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
> > index ac21db3..eb6125b 100644
> > --- a/drivers/acpi/pci_mcfg.c
> > +++ b/drivers/acpi/pci_mcfg.c
> > @@ -57,6 +57,37 @@ struct mcfg_fixup {
> > { "QCOM ", "QDF2432 ", 1, 5, MCFG_BUS_ANY, &pci_32b_ops },
> > { "QCOM ", "QDF2432 ", 1, 6, MCFG_BUS_ANY, &pci_32b_ops },
> > { "QCOM ", "QDF2432 ", 1, 7, MCFG_BUS_ANY, &pci_32b_ops },
> > +
> > +#ifdef CONFIG_PCI_XGENE
> As you've no doubt noticed, I'm proposing to add these quirks without
> CONFIG_PCI_XGENE, so we don't have to select each device when building
> a generic ACPI kernel.
>
> I'm also proposing some Kconfig and Makefile changes so we don't build
> the platform driver part in a generic ACPI kernel (unless we *also*
> explicitly select the platform driver).
>
> Here's an example:
> https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/commit/?h=pci/ecam&id=f80edf4d6c05
>
> >
> > +#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),
> >
> > @@ -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
> This isn't used anywhere, which makes me wonder whether it's worth
> keeping it.
>
> >
> > 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;
> > + }
> I would really, really like to figure out a way to get rid of these
> "if (acpi_disabled)" checks sprinkled through here. Is there any way
> we can set up bus->sysdata to be the same, regardless of whether we're
> using this as a platform driver or an ACPI quirk?
>
> >
> > +#ifdef CONFIG_ACPI
> You've probably noticed that I've been using
>
> #if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS)
>
> in this situation, mostly to make it clear that this is part of a
> workaround. I don't want people to blindly copy this stuff without
> realizing that it's a workaround for a hardware issue.
>
> >
> > +static struct resource xgene_v1_csr_res[] = {
> > + [0] = DEFINE_RES_MEM_NAMED(0x1f2b0000UL, SZ_64K, "PCIe CSR"),
> > + [1] = DEFINE_RES_MEM_NAMED(0x1f2c0000UL, SZ_64K, "PCIe CSR"),
> > + [2] = DEFINE_RES_MEM_NAMED(0x1f2d0000UL, SZ_64K, "PCIe CSR"),
> > + [3] = DEFINE_RES_MEM_NAMED(0x1f500000UL, SZ_64K, "PCIe CSR"),
> > + [4] = DEFINE_RES_MEM_NAMED(0x1f510000UL, SZ_64K, "PCIe CSR"),
> I assume these ranges are not the actual ECAM space, right?
> If they *were* ECAM, I assume you would have included them in the
> quirk itself in the mcfg_quirks[] table.
These are base addresses for some RC mmio registers.
>
> >
> > +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];
> This makes me nervous because root->segment comes from the ACPI _SEG,
> and if firmware gives us junk in _SEG, we will reference something in
> the weeds.
The SoC provide some number of RC bridges, each with a different base
for some mmio registers. Even if segment is legitimate in MCFG, there
is still a problem if a platform doesn't use the segment ordering
implied by the code. But the PNP0A03 _CRS does have this base address
as the first memory resource, so we could get it from there and not
have hard-coded addresses and implied ording in the quirk code.
I have tested a modified version of these quirks using this to
get the CSR base and it works on the 3 different platforms I have
access to.
static int xgene_pcie_get_csr(struct device *dev, struct resource *r)
{
struct acpi_device *adev = to_acpi_device(dev);
unsigned long flags;
struct list_head list;
struct resource_entry *entry;
int ret;
INIT_LIST_HEAD(&list);
flags = IORESOURCE_MEM;
ret = acpi_dev_get_resources(adev, &list,
acpi_dev_filter_resource_type_cb,
(void *)flags);
if (ret < 0) {
dev_err(dev, "failed to parse _CRS, error: %d\n", ret);
return ret;
} else if (ret == 0) {
dev_err(dev, "no memory resources present in _CRS\n");
return -EINVAL;
}
entry = list_first_entry(&list, struct resource_entry, node);
*r = *entry->res;
acpi_dev_free_resource_list(&list);
return 0;
}
>
> >
> > + 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;
> All these init functions are almost identical. Can we factor this out
> by having wrappers that do nothing more than pass in the table and
> version, and put the kzalloc and ioremap in a shared back-end?
>
> We're so close I can taste it! I can't wait to see all this work come
> to fruition.
>
> Bjorn
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