[PATCH v5] PCI: ARM: add support for generic PCI host controller
Will Deacon
will.deacon at arm.com
Mon Mar 3 13:46:40 EST 2014
This patch adds support for a generic PCI host controller, such as a
firmware-initialised device with static windows or an emulation by
something such as kvmtool.
The controller itself has no configuration registers and has its address
spaces described entirely by the device-tree (using the bindings from
ePAPR). Both CAM and ECAM are supported for Config Space accesses.
Corresponding documentation is added for the DT binding.
Signed-off-by: Will Deacon <will.deacon at arm.com>
---
Hi,
This is version 5 of the patches previously posted here:
v1: http://lists.infradead.org/pipermail/linux-arm-kernel/2014-February/229679.html
v2: http://lists.infradead.org/pipermail/linux-arm-kernel/2014-February/232213.html
v3: http://lists.infradead.org/pipermail/linux-arm-kernel/2014-February/233491.html
v4: http://lists.infradead.org/pipermail/linux-arm-kernel/2014-February/235468.html
Changes since v4 include:
- Changed binding example to use I/O bus address 0x0
- Fixed and simplified rounding code for I/O ranges so that we don't
mess around with the registered resource
- Finally fixed I/O offset handling
Note that I didn't use of_property_read_bool for parsing "linux,pci-probe-only"
since that would interfere with "pci=firmware" being passed on the command
line (meaning we have a tri-state). I also didn't move the resource
registration into gen_pci_calc_*_offset, since that duplicates code and
complicates the freeing paths.
As per usual, all feedback welcome. The next step is probably to work out
a set of library functions that can be extracted from this driver.
Will
.../devicetree/bindings/pci/host-generic-pci.txt | 100 ++++++
drivers/pci/host/Kconfig | 7 +
drivers/pci/host/Makefile | 1 +
drivers/pci/host/pci-host-generic.c | 369 +++++++++++++++++++++
4 files changed, 477 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pci/host-generic-pci.txt
create mode 100644 drivers/pci/host/pci-host-generic.c
diff --git a/Documentation/devicetree/bindings/pci/host-generic-pci.txt b/Documentation/devicetree/bindings/pci/host-generic-pci.txt
new file mode 100644
index 000000000000..98788c153302
--- /dev/null
+++ b/Documentation/devicetree/bindings/pci/host-generic-pci.txt
@@ -0,0 +1,100 @@
+* Generic PCI host controller
+
+Firmware-initialised PCI host controllers and 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 require the
+configuration of a control interface by 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:
+
+
+Properties of the host controller node:
+
+- compatible : Must be "pci-host-cam-generic" or "pci-host-ecam-generic"
+ depending on the layout of configuration space (CAM vs
+ ECAM respectively).
+
+- device_type : Must be "pci".
+
+- ranges : As described in IEEE Std 1275-1994, but must provide
+ at least a definition of non-prefetchable memory. One
+ or both of prefetchable Memory and IO Space may also
+ be provided.
+
+- bus-range : Optional property (also described in IEEE Std 1275-1994)
+ to indicate the range of bus numbers for this controller.
+ If absent, defaults to <0 255> (i.e. all buses).
+
+- #address-cells : Must be 3.
+
+- #size-cells : Must be 2.
+
+- reg : The Configuration Space base address and size, as accessed
+ from the parent bus.
+
+
+Properties of the /chosen node:
+
+- linux,pci-probe-only
+ : Optional property which takes a single-cell argument.
+ If '0', then Linux will assign devices in its usual manner,
+ otherwise it will not try to assign devices and instead use
+ them as they are configured already.
+
+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 an offset.
+
+For CAM, this 24-bit offset is:
+
+ cfg_offset(bus, device, function, register) =
+ bus << 16 | device << 11 | function << 8 | register
+
+Whilst ECAM extends this by 4 bits to accomodate 4k of function space:
+
+ cfg_offset(bus, device, function, register) =
+ bus << 20 | device << 15 | function << 12 | 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>
+
+
+Example:
+
+pci {
+ compatible = "pci-host-cam-generic"
+ device_type = "pci";
+ #address-cells = <3>;
+ #size-cells = <2>;
+ bus-range = <0x0 0x1>;
+
+ // CPU_PHYSICAL(2) SIZE(2)
+ reg = <0x0 0x40000000 0x0 0x1000000>;
+
+ // BUS_ADDRESS(3) CPU_PHYSICAL(2) SIZE(2)
+ ranges = <0x0000000 0x0 0x01000000 0x0 0x01000000 0x0 0x00010000>,
+ <0x1000000 0x0 0x41000000 0x0 0x41000000 0x0 0x3f000000>;
+
+
+ #interrupt-cells = <0x1>;
+
+ // PCI_DEVICE(3) INT#(1) CONTROLLER(PHANDLE) CONTROLLER_DATA(3)
+ interrupt-map = < 0x0 0x0 0x0 0x1 &gic 0x0 0x4 0x1
+ 0x800 0x0 0x0 0x1 &gic 0x0 0x5 0x1
+ 0x1000 0x0 0x0 0x1 &gic 0x0 0x6 0x1
+ 0x1800 0x0 0x0 0x1 &gic 0x0 0x7 0x1>;
+
+ // PCI_DEVICE(3) INT#(1)
+ interrupt-map-mask = <0xf800 0x0 0x0 0x7>;
+}
diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
index 47d46c6d8468..f91637d47065 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_HOST_GENERIC
+ bool "Generic PCI host controller"
+ depends on ARM && OF
+ help
+ Say Y here if you want to support a simple generic 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..bd1bf1ab4ac8 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_HOST_GENERIC) += pci-host-generic.o
diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
new file mode 100644
index 000000000000..b761f3e64a6a
--- /dev/null
+++ b/drivers/pci/host/pci-host-generic.c
@@ -0,0 +1,369 @@
+/*
+ * Simple, generic PCI host controller driver targetting firmware-initialised
+ * systems and 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 at arm.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_pci.h>
+#include <linux/platform_device.h>
+
+struct gen_pci_cfg_bus_ops {
+ u32 bus_shift;
+ void __iomem *(*map_bus)(struct pci_bus *, unsigned int, int);
+};
+
+struct gen_pci_cfg_windows {
+ struct resource res;
+ struct resource bus_range;
+ void __iomem **win;
+
+ const struct gen_pci_cfg_bus_ops *ops;
+};
+
+struct gen_pci {
+ struct pci_host_bridge host;
+ struct gen_pci_cfg_windows cfg;
+};
+
+static void __iomem *gen_pci_map_cfg_bus_cam(struct pci_bus *bus,
+ unsigned int devfn,
+ int where)
+{
+ struct pci_sys_data *sys = bus->sysdata;
+ struct gen_pci *pci = sys->private_data;
+ resource_size_t idx = bus->number - pci->cfg.bus_range.start;
+
+ return pci->cfg.win[idx] + ((devfn << 8) | where);
+}
+
+static struct gen_pci_cfg_bus_ops gen_pci_cfg_cam_bus_ops = {
+ .bus_shift = 16,
+ .map_bus = gen_pci_map_cfg_bus_cam,
+};
+
+static void __iomem *gen_pci_map_cfg_bus_ecam(struct pci_bus *bus,
+ unsigned int devfn,
+ int where)
+{
+ struct pci_sys_data *sys = bus->sysdata;
+ struct gen_pci *pci = sys->private_data;
+ resource_size_t idx = bus->number - pci->cfg.bus_range.start;
+
+ return pci->cfg.win[idx] + ((devfn << 12) | where);
+}
+
+static struct gen_pci_cfg_bus_ops gen_pci_cfg_ecam_bus_ops = {
+ .bus_shift = 20,
+ .map_bus = gen_pci_map_cfg_bus_ecam,
+};
+
+static int gen_pci_config_read(struct pci_bus *bus, unsigned int devfn,
+ int where, int size, u32 *val)
+{
+ void __iomem *addr;
+ struct pci_sys_data *sys = bus->sysdata;
+ struct gen_pci *pci = sys->private_data;
+
+ addr = pci->cfg.ops->map_bus(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 gen_pci_config_write(struct pci_bus *bus, unsigned int devfn,
+ int where, int size, u32 val)
+{
+ void __iomem *addr;
+ struct pci_sys_data *sys = bus->sysdata;
+ struct gen_pci *pci = sys->private_data;
+
+ addr = pci->cfg.ops->map_bus(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 gen_pci_ops = {
+ .read = gen_pci_config_read,
+ .write = gen_pci_config_write,
+};
+
+static int gen_pci_calc_io_offset(struct device *dev,
+ struct of_pci_range *range,
+ struct resource *res,
+ resource_size_t *offset)
+{
+ static atomic_t wins = ATOMIC_INIT(0);
+ int err, idx, max_win;
+ unsigned int window;
+
+ if (!PAGE_ALIGNED(range->cpu_addr))
+ return -EINVAL;
+
+ max_win = (IO_SPACE_LIMIT + 1) / SZ_64K;
+ idx = atomic_inc_return(&wins);
+ if (idx >= max_win)
+ return -ENOSPC;
+
+ window = (idx - 1) * SZ_64K;
+ err = pci_ioremap_io(window, range->cpu_addr);
+ if (err)
+ return err;
+
+ of_pci_range_to_resource(range, dev->of_node, res);
+ res->start = window;
+ res->end = res->start + range->size - 1;
+ *offset = window - range->pci_addr;
+ return 0;
+}
+
+static int gen_pci_calc_mem_offset(struct device *dev,
+ struct of_pci_range *range,
+ struct resource *res,
+ resource_size_t *offset)
+{
+ of_pci_range_to_resource(range, dev->of_node, res);
+ *offset = range->cpu_addr - range->pci_addr;
+ return 0;
+}
+
+static const struct of_device_id gen_pci_of_match[] = {
+ { .compatible = "pci-host-cam-generic",
+ .data = &gen_pci_cfg_cam_bus_ops },
+
+ { .compatible = "pci-host-ecam-generic",
+ .data = &gen_pci_cfg_ecam_bus_ops },
+
+ { },
+};
+MODULE_DEVICE_TABLE(of, gen_pci_of_match);
+
+static int gen_pci_setup(int nr, struct pci_sys_data *sys)
+{
+ int err, res_valid;
+ u8 bus_max;
+ struct pci_host_bridge_window *win;
+ struct resource *bus_range;
+ resource_size_t busn;
+ const char *type;
+ struct of_pci_range range;
+ struct of_pci_range_parser parser;
+ const struct of_device_id *of_id;
+ const int *prop;
+ struct gen_pci *pci = sys->private_data;
+ struct device *dev = pci->host.dev.parent;
+ struct device_node *np = dev->of_node;
+
+ type = of_get_property(np, "device_type", NULL);
+ if (!type || strcmp(type, "pci")) {
+ dev_err(dev, "invalid \"device_type\" %s\n", type);
+ return -EINVAL;
+ }
+
+ if (of_pci_range_parser_init(&parser, np)) {
+ dev_err(dev, "missing \"ranges\" property\n");
+ return -EINVAL;
+ }
+
+ prop = of_get_property(of_chosen, "linux,pci-probe-only", NULL);
+ if (prop) {
+ if (*prop)
+ pci_add_flags(PCI_PROBE_ONLY);
+ else
+ pci_clear_flags(PCI_PROBE_ONLY);
+ }
+
+ if (of_pci_parse_bus_range(np, &pci->cfg.bus_range))
+ pci->cfg.bus_range = (struct resource) {
+ .name = np->name,
+ .start = 0,
+ .end = 0xff,
+ .flags = IORESOURCE_BUS,
+ };
+
+ err = of_address_to_resource(np, 0, &pci->cfg.res);
+ if (err) {
+ dev_err(dev, "missing \"reg\" property\n");
+ return err;
+ }
+
+ pci->cfg.win = devm_kcalloc(dev, resource_size(&pci->cfg.bus_range),
+ sizeof(*pci->cfg.win), GFP_KERNEL);
+ if (!pci->cfg.win)
+ return -ENOMEM;
+
+ of_id = of_match_node(gen_pci_of_match, np);
+ pci->cfg.ops = of_id->data;
+ INIT_LIST_HEAD(&pci->host.windows);
+
+ /* Limit the bus-range to fit within reg */
+ bus_max = pci->cfg.bus_range.start +
+ (resource_size(&pci->cfg.res) >> pci->cfg.ops->bus_shift) - 1;
+ pci->cfg.bus_range.end = min_t(resource_size_t, pci->cfg.bus_range.end,
+ bus_max);
+
+ /* Create and register resources from the ranges property */
+ res_valid = 0;
+ for_each_of_pci_range(&parser, &range) {
+ struct resource *parent, *res;
+ resource_size_t offset;
+ u32 restype = range.flags & IORESOURCE_TYPE_BITS;
+
+ res = devm_kmalloc(dev, sizeof(*res), GFP_KERNEL);
+ if (!res) {
+ err = -ENOMEM;
+ goto out_release_res;
+ }
+
+ switch (restype) {
+ case IORESOURCE_IO:
+ parent = &ioport_resource;
+ err = gen_pci_calc_io_offset(dev, &range, res, &offset);
+ break;
+ case IORESOURCE_MEM:
+ parent = &iomem_resource;
+ err = gen_pci_calc_mem_offset(dev, &range, res, &offset);
+ res_valid |= !(res->flags & IORESOURCE_PREFETCH || err);
+ break;
+ default:
+ err = -EINVAL;
+ continue;
+ }
+
+ if (err) {
+ dev_warn(dev,
+ "error %d: failed to add resource [type 0x%x, %lld bytes]\n",
+ err, restype, range.size);
+ continue;
+ }
+
+ err = request_resource(parent, res);
+ if (err)
+ goto out_release_res;
+
+ pci_add_resource_offset(&sys->resources, res, offset);
+ }
+
+ if (!res_valid) {
+ dev_err(dev, "non-prefetchable memory resource required\n");
+ err = -EINVAL;
+ goto out_release_res;
+ }
+
+ /* Map our Configuration Space windows */
+ if (!request_mem_region(pci->cfg.res.start,
+ resource_size(&pci->cfg.res),
+ "Configuration Space"))
+ goto out_release_res;
+
+ bus_range = &pci->cfg.bus_range;
+ for (busn = bus_range->start; busn <= bus_range->end; ++busn) {
+ u32 idx = busn - bus_range->start;
+ u32 sz = 1 << pci->cfg.ops->bus_shift;
+
+ pci->cfg.win[idx] = devm_ioremap(dev,
+ pci->cfg.res.start + busn * sz,
+ sz);
+ if (!pci->cfg.win[idx]) {
+ err = -ENOMEM;
+ goto out_unmap_cfg;
+ }
+ }
+
+ /* Register bus resource */
+ pci_add_resource(&sys->resources, bus_range);
+ return 1;
+
+out_unmap_cfg:
+ while (busn-- > bus_range->start)
+ devm_iounmap(dev, pci->cfg.win[busn - bus_range->start]);
+
+out_release_res:
+ release_child_resources(&iomem_resource);
+ release_child_resources(&ioport_resource);
+
+ list_for_each_entry(win, &sys->resources, list)
+ devm_kfree(dev, win->res);
+ pci_free_resource_list(&sys->resources);
+
+ devm_kfree(dev, pci->cfg.win);
+ return err;
+}
+
+static int gen_pci_probe(struct platform_device *pdev)
+{
+ struct hw_pci hw;
+ struct gen_pci *pci;
+ struct device *dev = &pdev->dev;
+
+ if (!dev->of_node)
+ return -ENODEV;
+
+ pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
+ if (!pci)
+ return -ENOMEM;
+
+ pci->host.dev.parent = dev;
+ hw = (struct hw_pci) {
+ .nr_controllers = 1,
+ .private_data = (void **)&pci,
+ .setup = gen_pci_setup,
+ .map_irq = of_irq_parse_and_map_pci,
+ .ops = &gen_pci_ops,
+ };
+
+ pci_common_init_dev(dev, &hw);
+ return 0;
+}
+
+static struct platform_driver gen_pci_driver = {
+ .driver = {
+ .name = "pci-host-generic",
+ .owner = THIS_MODULE,
+ .of_match_table = gen_pci_of_match,
+ },
+ .probe = gen_pci_probe,
+};
+module_platform_driver(gen_pci_driver);
+
+MODULE_DESCRIPTION("Generic PCI host driver");
+MODULE_AUTHOR("Will Deacon <will.deacon at arm.com>");
+MODULE_LICENSE("GPLv2");
--
1.8.2.2
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