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

[G Gregory]

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@xxxxxxxxxxxx> 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@xxxxxxxxxxxx>
> >>>>---
> >>>>   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