[PATCH 2/3] PCI: ARM: add support for virtual PCI host controller

Liviu Dudau
2014-02-06T10:54:42Z

On Thu, Feb 06, 2014 at 08:54:03AM +0000, Anup Patel wrote:
> On Tue, Feb 4, 2014 at 10:23 PM, Will Deacon <will.deacon@arm.com> wrote:
> > This patch adds support for an extremely simple virtual PCI host
> > controller. The controller itself has no configuration registers, and
> > has its address spaces described entirely by the device-tree (using the
> > bindings described by ePAPR). This allows emulations, such as kvmtool,
> > to provide a simple means for a guest Linux instance to make use of
> > PCI devices.
> >
> > Corresponding documentation is added for the DT binding.
> >
> > Signed-off-by: Will Deacon <will.deacon@arm.com>
> > ---
> > .../devicetree/bindings/pci/linux,pci-virt.txt | 38 ++++
> > drivers/pci/host/Kconfig | 7 +
> > drivers/pci/host/Makefile | 1 +
> > drivers/pci/host/pci-virt.c | 200 +++++++++++++++++++++
> > 4 files changed, 246 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/pci/linux,pci-virt.txt
> > create mode 100644 drivers/pci/host/pci-virt.c
> >
> > diff --git a/Documentation/devicetree/bindings/pci/linux,pci-virt.txt b/Documentation/devicetree/bindings/pci/linux,pci-virt.txt
> > new file mode 100644
> > index 000000000000..54668a283498
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pci/linux,pci-virt.txt
> > @@ -0,0 +1,38 @@
> > +* ARM Basic Virtual PCI controller
> > +
> > +PCI emulations, such as the virtio-pci implementations found in kvmtool
> > +and other para-virtualised systems, do not require driver support for
> > +complexities such as regulator and clock management. In fact, the
> > +controller may not even have a control interface visible to the
> > +operating system, instead presenting a set of fixed windows describing a
> > +subset of IO, Memory and Configuration spaces.
> > +
> > +Such a controller can be described purely in terms of the standardized
> > +device tree bindings communicated in pci.txt:
> > +
> > +- compatible : Must be "linux,pci-virt"
> > +
> > +- ranges : As described in IEEE Std 1275-1994, but must provide
> > + at least a definition of the Configuration Space plus
> > + one or both of IO and Memory Space.
> > +
> > +- #address-cells : Must be 3
> > +
> > +- #size-cells : Must be 2
> > +
> > +Configuration Space is assumed to be memory-mapped (as opposed to being
>
> It would be great to have a flag to specify whether Configuration Space is over
> ioports or memory mapped.

This is another reason why I prefer the reg property for specifying the configuration
space address range. I don't see a straight way of making the distinction you
need using the ranges property.

>
> Regards,
> Anup
>
> > +accessed via an ioport) and laid out with a direct correspondence to the
> > +geography of a PCI bus address, by concatenating the various components
> > +to form a 24-bit offset:
> > +
> > + cfg_offset(bus, device, function, register) =
> > + bus << 16 | device << 11 | function << 8 | register
> > +
> > +Interrupt mapping is exactly as described in `Open Firmware Recommended
> > +Practice: Interrupt Mapping' and requires the following properties:
> > +
> > +- #interrupt-cells : Must be 1
> > +
> > +- interrupt-map : <see aforementioned specification>
> > +
> > +- interrupt-map-mask : <see aforementioned specification>
> > diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
> > index 47d46c6d8468..fd4460573b81 100644
> > --- a/drivers/pci/host/Kconfig
> > +++ b/drivers/pci/host/Kconfig
> > @@ -33,4 +33,11 @@ config PCI_RCAR_GEN2
> > There are 3 internal PCI controllers available with a single
> > built-in EHCI/OHCI host controller present on each one.
> >
> > +config PCI_VIRT_HOST
> > + bool "Virtual PCI host controller"
> > + depends on ARM && OF
> > + help
> > + Say Y here if you want to support a very simple virtual PCI
> > + host controller, such as the one emulated by kvmtool.
> > +
> > endmenu
> > diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
> > index 13fb3333aa05..9b6775d95d3b 100644
> > --- a/drivers/pci/host/Makefile
> > +++ b/drivers/pci/host/Makefile
> > @@ -4,3 +4,4 @@ obj-$(CONFIG_PCI_IMX6) += pci-imx6.o
> > obj-$(CONFIG_PCI_MVEBU) += pci-mvebu.o
> > obj-$(CONFIG_PCI_TEGRA) += pci-tegra.o
> > obj-$(CONFIG_PCI_RCAR_GEN2) += pci-rcar-gen2.o
> > +obj-$(CONFIG_PCI_VIRT_HOST) += pci-virt.o
> > diff --git a/drivers/pci/host/pci-virt.c b/drivers/pci/host/pci-virt.c
> > new file mode 100644
> > index 000000000000..ded01474453b
> > --- /dev/null
> > +++ b/drivers/pci/host/pci-virt.c
> > @@ -0,0 +1,200 @@
> > +/*
> > + * Very basic PCI host controller driver targetting virtual machines
> > + * (e.g. the PCI emulation provided by kvmtool).
> > + *
> > + * 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.
> > + *
> > + * 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 for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> > + *
> > + * Copyright (C) 2014 ARM Limited
> > + *
> > + * Author: Will Deacon <will.deacon@arm.com>
> > + *
> > + * This driver currently supports (per instance):
> > + * - A single controller
> > + * - A single memory space and/or port space
> > + * - A memory-mapped configuration space
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_pci.h>
> > +#include <linux/platform_device.h>
> > +
> > +struct virt_pci {
> > + struct device *dev;
> > +
> > + struct resource cfg;
> > + struct resource io;
> > + struct resource mem;
> > +
> > + void __iomem *cfg_base;
> > +};
> > +
> > +static void __iomem *virt_pci_config_address(struct pci_bus *bus,
> > + unsigned int devfn,
> > + int where)
> > +{
> > + struct pci_sys_data *sys = bus->sysdata;
> > + struct virt_pci *pci = sys->private_data;
> > + void __iomem *addr = pci->cfg_base;
> > +
> > + /*
> > + * We construct config space addresses by simply sandwiching
> > + * together all of the PCI address components and using the
> > + * result as an offset into a 16M region.
> > + */
> > + return addr + (((u32)bus->number << 16) | (devfn << 8) | where);
> > +}
> > +
> > +
> > +static int virt_pci_config_read(struct pci_bus *bus, unsigned int devfn,
> > + int where, int size, u32 *val)
> > +{
> > + void __iomem *addr = virt_pci_config_address(bus, devfn, where);
> > +
> > + switch (size) {
> > + case 1:
> > + *val = readb(addr);
> > + break;
> > + case 2:
> > + *val = readw(addr);
> > + break;
> > + default:
> > + *val = readl(addr);
> > + }
> > +
> > + return PCIBIOS_SUCCESSFUL;
> > +}
> > +
> > +static int virt_pci_config_write(struct pci_bus *bus, unsigned int devfn,
> > + int where, int size, u32 val)
> > +{
> > + void __iomem *addr = virt_pci_config_address(bus, devfn, where);
> > +
> > + switch (size) {
> > + case 1:
> > + writeb(val, addr);
> > + break;
> > + case 2:
> > + writew(val, addr);
> > + break;
> > + default:
> > + writel(val, addr);
> > + }
> > +
> > + return PCIBIOS_SUCCESSFUL;
> > +}
> > +
> > +static struct pci_ops virt_pci_ops = {
> > + .read = virt_pci_config_read,
> > + .write = virt_pci_config_write,
> > +};
> > +
> > +static int virt_pci_setup(int nr, struct pci_sys_data *sys)
> > +{
> > + struct virt_pci *pci = sys->private_data;
> > +
> > + if (resource_type(&pci->io)) {
> > + pci_add_resource(&sys->resources, &pci->io);
> > + pci_ioremap_io(nr * resource_size(&pci->io), pci->io.start);
> > + }
> > +
> > + if (resource_type(&pci->mem))
> > + pci_add_resource(&sys->resources, &pci->mem);
> > +
> > + pci->cfg_base = devm_ioremap_resource(pci->dev, &pci->cfg);
> > + return !IS_ERR(pci->cfg_base);
> > +}
> > +
> > +static const struct of_device_id virt_pci_of_match[] = {
> > + { .compatible = "linux,pci-virt" },
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(of, virt_pci_of_match);
> > +
> > +static int virt_pci_probe(struct platform_device *pdev)
> > +{
> > + struct hw_pci hw;
> > + struct of_pci_range range;
> > + struct of_pci_range_parser parser;
> > + struct virt_pci *pci;
> > + struct device *dev = &pdev->dev;
> > + struct device_node *np = dev->of_node;
> > +
> > + if (of_pci_range_parser_init(&parser, np)) {
> > + dev_err(dev, "missing \"ranges\" property\n");
> > + return -EINVAL;
> > + }
> > +
> > + pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
> > + if (!pci)
> > + return -ENOMEM;
> > +
> > + pci->dev = dev;
> > + for_each_of_pci_range(&parser, &range) {
> > + u32 restype = range.flags & IORESOURCE_TYPE_BITS;
> > +
> > + switch (restype) {
> > + case IORESOURCE_IO:
> > + if (resource_type(&pci->io))
> > + dev_warn(dev,
> > + "ignoring additional io resource\n");
> > + else
> > + of_pci_range_to_resource(&range, np, &pci->io);
> > + break;
> > + case IORESOURCE_MEM:
> > + if (resource_type(&pci->mem))
> > + dev_warn(dev,
> > + "ignoring additional mem resource\n");
> > + else
> > + of_pci_range_to_resource(&range, np, &pci->mem);
> > + break;
> > + case 0: /* cfg */
> > + if (resource_type(&pci->cfg)) {
> > + dev_warn(dev,
> > + "ignoring additional cfg resource\n");
> > + } else {
> > + of_pci_range_to_resource(&range, np, &pci->cfg);
> > + pci->cfg.flags |= IORESOURCE_MEM;
> > + }
> > + break;
> > + default:
> > + dev_warn(dev,
> > + "ignoring unknown/unsupported resource type %x\n",
> > + restype);
> > + }
> > + }
> > +
> > + memset(&hw, 0, sizeof(hw));
> > + hw.nr_controllers = 1;
> > + hw.private_data = (void **)&pci;
> > + hw.setup = virt_pci_setup;
> > + hw.map_irq = of_irq_parse_and_map_pci;
> > + hw.ops = &virt_pci_ops;
> > + pci_common_init_dev(dev, &hw);
> > + return 0;
> > +}
> > +
> > +static struct platform_driver virt_pci_driver = {
> > + .driver = {
> > + .name = "pci-virt",
> > + .owner = THIS_MODULE,
> > + .of_match_table = virt_pci_of_match,
> > + },
> > + .probe = virt_pci_probe,
> > +};
> > +module_platform_driver(virt_pci_driver);
> > +
> > +MODULE_DESCRIPTION("Virtual PCI host driver");
> > +MODULE_AUTHOR("Will Deacon <will.deacon@arm.com>");
> > +MODULE_LICENSE("GPLv2");
> > --
> > 1.8.2.2
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
?\_(?)_/?

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