Re: [Linaro-acpi] [PATCH V6 12/13] pci, pci-thunder-ecam: Add ACPI support for ThunderX ECAM.

G Gregory
2016-04-19T12:29:08Z

On Tue, Apr 19, 2016 at 01:22:29PM +0200, Tomasz Nowicki wrote:
>
>
> On 19.04.2016 13:12, Graeme Gregory wrote:
> >On Tue, Apr 19, 2016 at 11:41:29AM +0100, G Gregory wrote:
> >>On 19 April 2016 at 11:26, Tomasz Nowicki <tn@semihalf.com> wrote:
> >>>On 15.04.2016 19:06, Tomasz Nowicki wrote:
> >>>>
> >>>>Passes 1.x miss PCI enhanced allocation (EA) header for fixed-BARs,
> >>>>thus these passes should use Cavium-specific config access functions
> >>>>that synthesize the missing EA capabilities.
> >>>>
> >>>>We already have DT driver which addresses errata requirements and
> >>>>allows to use special PCI config accessors. Currently this driver uses
> >>>>compatible = "cavium,pci-host-thunder-ecam" to mach against the errata.
> >>>>For ACPI case we need explicit errata number and corresponding
> >>>>DECLARE_ACPI_MCFG_FIXUP fixup code.
> >>>>
> >>>>Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> >>>>---
> >>>> arch/arm64/Kconfig | 14 ++++++++++++++
> >>>> arch/arm64/include/asm/cpufeature.h | 3 ++-
> >>>> arch/arm64/kernel/cpu_errata.c | 8 ++++++++
> >>>> drivers/pci/host/pci-thunder-ecam.c | 35
> >>>>+++++++++++++++++++++++++++++++++++
> >>>> 4 files changed, 59 insertions(+), 1 deletion(-)
> >>>>
> >>>>diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> >>>>index 1bded87..b7614b8 100644
> >>>>--- a/arch/arm64/Kconfig
> >>>>+++ b/arch/arm64/Kconfig
> >>>>@@ -445,6 +445,20 @@ config CAVIUM_ERRATUM_27456
> >>>>
> >>>> If unsure, say Y.
> >>>>
> >>>>+config CAVIUM_ERRATUM_24575
> >>>>+ bool "Cavium erratum 24575: Enhanced Allocation (EA) emualaion"
> >>>>+ default y
> >>>>+ help
> >>>>+ Enable workaround for erratum 24575.
> >>>>+
> >>>>+ Early versions of the Cavium Thunder CN88XX processor are
> >>>>missing
> >>>>+ Enhanced Allocation (EA) capabilities for the fixed BAR
> >>>>addresses used
> >>>>+ by the on-SoC hardware blocks. The erratum adds config access
> >>>>+ functions that synthesize the missing EA capabilities for
> >>>>versions
> >>>>+ that are missing that information.
> >>>>+
> >>>>+ If unsure, say Y.
> >>>>+
> >>>> endmenu
> >>>>
> >>>>
> >>>>diff --git a/arch/arm64/include/asm/cpufeature.h
> >>>>b/arch/arm64/include/asm/cpufeature.h
> >>>>index b9b6494..a78364e 100644
> >>>>--- a/arch/arm64/include/asm/cpufeature.h
> >>>>+++ b/arch/arm64/include/asm/cpufeature.h
> >>>>@@ -35,8 +35,9 @@
> >>>> #define ARM64_ALT_PAN_NOT_UAO 10
> >>>> #define ARM64_HAS_VIRT_HOST_EXTN 11
> >>>> #define ARM64_WORKAROUND_CAVIUM_27456 12
> >>>>+#define ARM64_WORKAROUND_CAVIUM_24575 13
> >>>>
> >>>>-#define ARM64_NCAPS 13
> >>>>+#define ARM64_NCAPS 14
> >>>>
> >>>> #ifndef __ASSEMBLY__
> >>>>
> >>>>diff --git a/arch/arm64/kernel/cpu_errata.c
> >>>>b/arch/arm64/kernel/cpu_errata.c
> >>>>index 06afd04..89c13d7 100644
> >>>>--- a/arch/arm64/kernel/cpu_errata.c
> >>>>+++ b/arch/arm64/kernel/cpu_errata.c
> >>>>@@ -97,6 +97,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
> >>>> (1 << MIDR_VARIANT_SHIFT) | 1),
> >>>> },
> >>>> #endif
> >>>>+#ifdef CONFIG_CAVIUM_ERRATUM_24575
> >>>>+ {
> >>>>+ /* Cavium ThunderX, pass 1.x */
> >>>>+ .desc = "Cavium erratum 24575",
> >>>>+ .capability = ARM64_WORKAROUND_CAVIUM_24575,
> >>>>+ MIDR_RANGE(MIDR_THUNDERX, 0x00, 0x01),
> >>>>+ },
> >>>>+#endif
> >>>> {
> >>>> }
> >>>> };
> >>>>diff --git a/drivers/pci/host/pci-thunder-ecam.c
> >>>>b/drivers/pci/host/pci-thunder-ecam.c
> >>>>index f67c6d7..01de697 100644
> >>>>--- a/drivers/pci/host/pci-thunder-ecam.c
> >>>>+++ b/drivers/pci/host/pci-thunder-ecam.c
> >>>>@@ -11,10 +11,14 @@
> >>>> #include <linux/ioport.h>
> >>>> #include <linux/of_pci.h>
> >>>> #include <linux/of.h>
> >>>>+#include <linux/pci-acpi.h>
> >>>> #include <linux/platform_device.h>
> >>>>
> >>>>+#include <asm/virt.h>
> >>>>+
> >>>> #include "../ecam.h"
> >>>>
> >>>>+
> >>>> static void set_val(u32 v, int where, int size, u32 *val)
> >>>> {
> >>>> int shift = (where & 3) * 8;
> >>>>@@ -376,5 +380,36 @@ static struct platform_driver thunder_ecam_driver = {
> >>>> };
> >>>> module_platform_driver(thunder_ecam_driver);
> >>>>
> >>>>+#ifdef CONFIG_ACPI
> >>>>+
> >>>>+static bool needs_cavium_erratum_24575(struct pci_cfg_fixup *fixup,
> >>>>+ struct acpi_pci_root *root)
> >>>>+{
> >>>>+ /*
> >>>>+ * We must match errata code and be hypervisor, quirk does not
> >>>>apply
> >>>>+ * for virtual machines.
> >>>>+ */
> >>>>+ return cpus_have_cap(ARM64_WORKAROUND_CAVIUM_24575) &&
> >>>>+ is_hyp_mode_available();
> >>>>+}
> >>>>+
> >>>>+DECLARE_ACPI_MCFG_FIXUP(NULL, needs_cavium_erratum_24575,
> >>>>&pci_thunder_ecam_ops,
> >>>>+ 0, PCI_MCFG_BUS_ANY);
> >>>>+DECLARE_ACPI_MCFG_FIXUP(NULL, needs_cavium_erratum_24575,
> >>>>&pci_thunder_ecam_ops,
> >>>>+ 1, PCI_MCFG_BUS_ANY);
> >>>>+DECLARE_ACPI_MCFG_FIXUP(NULL, needs_cavium_erratum_24575,
> >>>>&pci_thunder_ecam_ops,
> >>>>+ 2, PCI_MCFG_BUS_ANY);
> >>>>+DECLARE_ACPI_MCFG_FIXUP(NULL, needs_cavium_erratum_24575,
> >>>>&pci_thunder_ecam_ops,
> >>>>+ 3, PCI_MCFG_BUS_ANY);
> >>>>+DECLARE_ACPI_MCFG_FIXUP(NULL, needs_cavium_erratum_24575,
> >>>>&pci_thunder_ecam_ops,
> >>>>+ 10, PCI_MCFG_BUS_ANY);
> >>>>+DECLARE_ACPI_MCFG_FIXUP(NULL, needs_cavium_erratum_24575,
> >>>>&pci_thunder_ecam_ops,
> >>>>+ 11, PCI_MCFG_BUS_ANY);
> >>>>+DECLARE_ACPI_MCFG_FIXUP(NULL, needs_cavium_erratum_24575,
> >>>>&pci_thunder_ecam_ops,
> >>>>+ 12, PCI_MCFG_BUS_ANY);
> >>>>+DECLARE_ACPI_MCFG_FIXUP(NULL, needs_cavium_erratum_24575,
> >>>>&pci_thunder_ecam_ops,
> >>>>+ 13, PCI_MCFG_BUS_ANY);
> >>>>+#endif
> >>>>+
> >>>
> >>>
> >>>I wonder if we can identify quirk based on _DSD properties, like that:
> >>>
> >>>Name (_DSD, Package () {
> >>> ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> >>> Package () {
> >>> Package (2) {"cavium,pci-host-thunder-ecam", 1},
> >>> }
> >>>})
> >>>
> >>>similar for PEM driver:
> >>>
> >>>Name (_DSD, Package () {
> >>> ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> >>> Package () {
> >>> Package (2) {"cavium,pci-host-thunder-pem", 1},
> >>> }
> >>>})
> >>>
> >>>Do you think it is right thing to do?
> >>>
> >>
> >>Well if your adding new properties why not add a Cavium specific _CID?
> >>
> >
> >For clarity what I mean is something like this allowed.
> >
> >Device (PCI0)
> >{
> > Name (_HID, EisaId ("PNP0A08"))
> > Name (_CID, EisaId ("PNP0A03"))
> > Name (_HID, "CAV0666")) // Cavium Quirky Hardware
> >
> > ....
> >
> >}
> >
>
> Rafael, Bjorn, what do you think?
>

Another option as has been pointed out to me is that devices that are
not compliant don't advertise the IDs PNP0A03/8 and should use hardware
specific IDs.

Obviously in linux the drivers for them would re-use 90% of the generic
code with just their added accessors.

I do not know though what knock-on effects that would have and if there
is stuff that relies on the host bridge being IDed as the standard one.

Graeme