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@xxxxxxx> --- .../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 +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@xxxxxxx> + * + * 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@xxxxxxx>"); +MODULE_LICENSE("GPLv2"); -- 1.8.2.2 -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
