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    SubjectRe: [PATCH V7 08/11] pci, acpi: Support for ACPI based generic PCI host controller
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    On 10/05/16 17:19, Tomasz Nowicki wrote:
    > This patch is going to implement generic PCI host controller for
    > ACPI world, similar to what pci-host-generic.c driver does for DT world.
    >
    > All such drivers, which we have seen so far, were implemented within
    > arch/ directory since they had some arch assumptions (x86 and ia64).
    > However, they all are doing similar thing, so it makes sense to find
    > some common code and abstract it into the generic driver.
    >
    > In order to handle PCI config space regions properly, we define new
    > MCFG interface which does sanity checks on MCFG table and keeps its
    > root pointer. User is able to lookup MCFG regions based on that root
    > pointer and specified domain:bus_start:bus_end touple. We are using
    > pci_mmcfg_late_init old prototype to avoid another function name.
    >
    > The implementation of pci_acpi_scan_root() looks up the MCFG entries
    > and sets up a new mapping (regions are not mapped until host controller ask
    > for it). Generic PCI functions are used for accessing config space.
    > Driver selects PCI_ECAM and uses functions from drivers/pci/ecam.h
    > to create and access ECAM mappings.
    >
    > As mentioned in Kconfig help section, ACPI_PCI_HOST_GENERIC choice
    > should be made on a per-architecture basis.
    >
    > Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
    > Signed-off-by: Jayachandran C <jchandra@broadcom.com>
    > ---
    > drivers/acpi/Kconfig | 8 +++
    > drivers/acpi/Makefile | 1 +
    > drivers/acpi/pci_mcfg.c | 97 ++++++++++++++++++++++++++
    > drivers/acpi/pci_root_generic.c | 149 ++++++++++++++++++++++++++++++++++++++++
    > drivers/pci/ecam.h | 5 ++
    > include/linux/pci-acpi.h | 5 ++
    > include/linux/pci.h | 5 +-
    > 7 files changed, 269 insertions(+), 1 deletion(-)
    > create mode 100644 drivers/acpi/pci_mcfg.c
    > create mode 100644 drivers/acpi/pci_root_generic.c
    >
    > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
    > index 183ffa3..44afc76 100644
    > --- a/drivers/acpi/Kconfig
    > +++ b/drivers/acpi/Kconfig
    > @@ -346,6 +346,14 @@ config ACPI_PCI_SLOT
    > i.e., segment/bus/device/function tuples, with physical slots in
    > the system. If you are unsure, say N.
    >
    > +config ACPI_PCI_HOST_GENERIC
    > + bool
    > + select PCI_ECAM
    > + help
    > + Select this config option from the architecture Kconfig,
    > + if it is preferred to enable ACPI PCI host controller driver which
    > + has no arch-specific assumptions.
    > +
    > config X86_PM_TIMER
    > bool "Power Management Timer Support" if EXPERT
    > depends on X86
    > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
    > index 81e5cbc..627a2b7 100644
    > --- a/drivers/acpi/Makefile
    > +++ b/drivers/acpi/Makefile
    > @@ -40,6 +40,7 @@ acpi-$(CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC) += processor_pdc.o
    > acpi-y += ec.o
    > acpi-$(CONFIG_ACPI_DOCK) += dock.o
    > acpi-y += pci_root.o pci_link.o pci_irq.o
    > +obj-$(CONFIG_ACPI_PCI_HOST_GENERIC) += pci_root_generic.o pci_mcfg.o
    > acpi-y += acpi_lpss.o acpi_apd.o
    > acpi-y += acpi_platform.o
    > acpi-y += acpi_pnp.o
    > diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
    > new file mode 100644
    > index 0000000..373d079
    > --- /dev/null
    > +++ b/drivers/acpi/pci_mcfg.c
    > @@ -0,0 +1,97 @@
    > +/*
    > + * Copyright (C) 2016 Broadcom
    > + * Author: Jayachandran C <jchandra@broadcom.com>
    > + * Copyright (C) 2016 Semihalf
    > + * Author: Tomasz Nowicki <tn@semihalf.com>
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License, version 2, as
    > + * published by the Free Software Foundation (the "GPL").
    > + *
    > + * This program is distributed in the hope that it will be useful, but
    > + * WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    > + * General Public License version 2 (GPLv2) for more details.
    > + *
    > + * You should have received a copy of the GNU General Public License
    > + * version 2 (GPLv2) along with this source code.
    > + */
    > +#include <linux/kernel.h>
    > +#include <linux/pci.h>
    > +#include <linux/pci-acpi.h>
    > +
    > +#define PREFIX "ACPI: "
    > +
    > +/* Root pointer to the mapped MCFG table */
    > +static struct acpi_table_mcfg *mcfg_table;
    > +
    > +#define MCFG_ENTRIES(mcfg_ptr) (((mcfg_ptr)->header.length - \
    > + sizeof(struct acpi_table_mcfg)) / \
    > + sizeof(struct acpi_mcfg_allocation))
    > +
    > +static phys_addr_t pci_mcfg_lookup_static(u16 seg, u8 bus_start, u8 bus_end)
    > +{
    > + struct acpi_mcfg_allocation *mptr;
    > + int i;
    > +
    > + if (!mcfg_table) {
    > + pr_err(PREFIX "MCFG table not available, lookup failed\n");
    > + return -ENXIO;
    > + }
    > +
    > + mptr = (struct acpi_mcfg_allocation *) &mcfg_table[1];
    > +
    > + /*
    > + * We expect exact match, unless MCFG entry end bus covers more than
    > + * specified by caller.
    > + */
    > + for (i = 0; i < MCFG_ENTRIES(mcfg_table); i++, mptr++) {
    > + if (mptr->pci_segment == seg &&
    > + mptr->start_bus_number == bus_start &&
    > + mptr->end_bus_number >= bus_end) {
    > + return mptr->address;
    > + }
    > + }
    > +
    > + return -ENXIO;
    > +}
    > +
    > +phys_addr_t pci_mcfg_lookup(struct acpi_device *device, u16 seg,
    > + struct resource *bus_res)
    > +{
    > + phys_addr_t addr;
    > +
    > + addr = acpi_pci_root_get_mcfg_addr(device->handle);
    > + if (addr)
    > + return addr;
    > +
    > + return pci_mcfg_lookup_static(seg, bus_res->start, bus_res->end);
    > +}
    > +
    > +static __init int pci_mcfg_parse(struct acpi_table_header *header)
    > +{
    > + struct acpi_table_mcfg *mcfg;
    > + int n;
    > +
    > + if (!header)
    > + return -EINVAL;

    Maybe that's bike shedding, but acpi_table_parse already checks that the
    table passed to the handler exists, so this is redundant.

    Regards,
    Matthias

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