On Thu, 19 Aug 2021, Rahul Singh wrote:
> XEN during boot will read the PCI device tree node “reg” property
> and will map the PCI config space to the XEN memory.
>
> As of now "pci-host-ecam-generic" compatible board is supported.
>
> "linux,pci-domain" device tree property assigns a fixed PCI domain
> number to a host bridge, otherwise an unstable (across boots) unique
> number will be assigned by Linux.This property has to be in sync with
> XEN to access the PCI devices.
>
> XEN will read the “linux,pci-domain” property from the device tree node
> and configure the host bridge segment number accordingly. If this
> property is not available XEN will allocate the unique segment number
> to the host bridge.
>
> dt_get_pci_domain_nr(..) and dt_pci_bus_find_domain_nr(..) are directly
> imported from the Linux source tree.
>
> Signed-off-by: Rahul Singh <[email protected]>
> ---
> xen/arch/arm/pci/Makefile | 2 +
> xen/arch/arm/pci/pci-host-common.c | 261 ++++++++++++++++++++++++++++
> xen/arch/arm/pci/pci-host-generic.c | 55 ++++++
> xen/include/asm-arm/pci.h | 28 +++
> 4 files changed, 346 insertions(+)
> create mode 100644 xen/arch/arm/pci/pci-host-common.c
> create mode 100644 xen/arch/arm/pci/pci-host-generic.c
>
> diff --git a/xen/arch/arm/pci/Makefile b/xen/arch/arm/pci/Makefile
> index a9ee0b9b44..f3d97f859e 100644
> --- a/xen/arch/arm/pci/Makefile
> +++ b/xen/arch/arm/pci/Makefile
> @@ -1,2 +1,4 @@
> obj-y += pci.o
> obj-y += pci-access.o
> +obj-y += pci-host-generic.o
> +obj-y += pci-host-common.o
> diff --git a/xen/arch/arm/pci/pci-host-common.c
> b/xen/arch/arm/pci/pci-host-common.c
> new file mode 100644
> index 0000000000..9dd9b02271
> --- /dev/null
> +++ b/xen/arch/arm/pci/pci-host-common.c
> @@ -0,0 +1,261 @@
> +/*
> + * Copyright (C) 2021 Arm Ltd.
> + *
> + * Based on Linux drivers/pci/ecam.c
> + * Copyright 2016 Broadcom.
> + *
> + * Based on Linux drivers/pci/controller/pci-host-common.c
> + * Based on Linux drivers/pci/controller/pci-host-generic.c
> + * Copyright (C) 2014 ARM Limited Will Deacon <[email protected]>
> + *
> + *
> + * 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/>.
> + */
> +
> +#include <xen/init.h>
> +#include <xen/pci.h>
> +#include <asm/pci.h>
> +#include <xen/rwlock.h>
> +#include <xen/sched.h>
> +#include <xen/vmap.h>
> +
> +/*
> + * List for all the pci host bridges.
> + */
> +
> +static LIST_HEAD(pci_host_bridges);
> +
> +static atomic_t domain_nr = ATOMIC_INIT(-1);
> +
> +bool dt_pci_parse_bus_range(struct dt_device_node *dev,
> + struct pci_config_window *cfg)
> +{
> + const __be32 *cells;
> + uint32_t len;
> +
> + cells = dt_get_property(dev, "bus-range", &len);
> + /* bus-range should at least be 2 cells */
> + if ( !cells || (len < (sizeof(*cells) * 2)) )
> + return false;
> +
> + cfg->busn_start = dt_next_cell(1, &cells);
> + cfg->busn_end = dt_next_cell(1, &cells);
> +
> + return true;
> +}
> +
> +static inline void __iomem *pci_remap_cfgspace(paddr_t start, size_t len)
> +{
> + return ioremap_nocache(start, len);
> +}
> +
> +static void pci_ecam_free(struct pci_config_window *cfg)
> +{
> + if ( cfg->win )
> + iounmap(cfg->win);
> +
> + xfree(cfg);
> +}
> +
> +static struct pci_config_window *gen_pci_init(struct dt_device_node *dev,
> + int ecam_reg_idx)
If it is only called at init time, then the function should be __init
> +{
> + int err;
> + struct pci_config_window *cfg;
> + paddr_t addr, size;
> +
> + cfg = xzalloc(struct pci_config_window);
> + if ( !cfg )
> + return NULL;
> +
> + err = dt_pci_parse_bus_range(dev, cfg);
> + if ( !err ) {
> + cfg->busn_start = 0;
> + cfg->busn_end = 0xff;
> + printk(XENLOG_ERR "%s:No bus range found for pci controller\n",
> + dt_node_full_name(dev));
> + } else {
> + if ( cfg->busn_end > cfg->busn_start + 0xff )
> + cfg->busn_end = cfg->busn_start + 0xff;
Is this a hard limit in the specification? Or is it a limit in the Xen
implementation?
> + }
> +
> + /* Parse our PCI ecam register address*/
^ space
> + err = dt_device_get_address(dev, ecam_reg_idx, &addr, &size);
> + if ( err )
> + goto err_exit;
> +
> + cfg->phys_addr = addr;
> + cfg->size = size;
> +
> + /*
> + * On 64-bit systems, we do a single ioremap for the whole config space
> + * since we have enough virtual address range available. On 32-bit, we
> + * ioremap the config space for each bus individually.
> + *
> + * As of now only 64-bit is supported 32-bit is not supported.
> + */
> + cfg->win = pci_remap_cfgspace(cfg->phys_addr, cfg->size);
> + if ( !cfg->win )
> + goto err_exit_remap;
> +
> + printk("ECAM at [mem %lx-%lx] for [bus %x-%x] \n",cfg->phys_addr,
> + cfg->phys_addr + cfg->size - 1, cfg->busn_start, cfg->busn_end);
> +
> + return cfg;
> +
> +err_exit_remap:
> + printk(XENLOG_ERR "ECAM ioremap failed\n");
> +err_exit:
> + pci_ecam_free(cfg);
> + return NULL;
> +}
> +
> +struct pci_host_bridge *pci_alloc_host_bridge(void)
> +{
> + struct pci_host_bridge *bridge = xzalloc(struct pci_host_bridge);
> +
> + if ( !bridge )
> + return NULL;
> +
> + INIT_LIST_HEAD(&bridge->node);
> + bridge->bus_start = ~0;
> + bridge->bus_end = ~0;
Please use INVALID_PADDR instead of ~0
> + return bridge;
> +}
> +
> +void pci_add_host_bridge(struct pci_host_bridge *bridge)
> +{
> + list_add_tail(&bridge->node, &pci_host_bridges);
> +}
> +
> +static int pci_get_new_domain_nr(void)
> +{
> + return atomic_inc_return(&domain_nr);
> +}
> +
> +/*
> + * This function will try to obtain the host bridge domain number by
> + * finding a property called "linux,pci-domain" of the given device node.
> + *
> + * @node: device tree node with the domain information
> + *
> + * Returns the associated domain number from DT in the range [0-0xffff], or
> + * a negative value if the required property is not found.
> + */
> +static int dt_get_pci_domain_nr(struct dt_device_node *node)
> +{
> + u32 domain;
> + int error;
> +
> + error = dt_property_read_u32(node, "linux,pci-domain", &domain);
> + if ( !error )
> + return -EINVAL;
> +
> + return (u16)domain;
Let's check that domain <= UINT16_MAX
> +}
> +
> +static int pci_bus_find_domain_nr(struct dt_device_node *dev)
> +{
> + static int use_dt_domains = -1;
> + int domain;
> +
> + domain = dt_get_pci_domain_nr(dev);
> +
> + /*
> + * Check DT domain and use_dt_domains values.
> + *
> + * If DT domain property is valid (domain >= 0) and
> + * use_dt_domains != 0, the DT assignment is valid since this means
> + * we have not previously allocated a domain number by using
> + * pci_get_new_domain_nr(); we should also update use_dt_domains to
> + * 1, to indicate that we have just assigned a domain number from
> + * DT.
> + *
> + * If DT domain property value is not valid (ie domain < 0), and we
> + * have not previously assigned a domain number from DT
> + * (use_dt_domains != 1) we should assign a domain number by
> + * using the:
> + *
> + * pci_get_new_domain_nr()
> + *
> + * API and update the use_dt_domains value to keep track of method we
> + * are using to assign domain numbers (use_dt_domains = 0).
> + *
> + * All other combinations imply we have a platform that is trying
> + * to mix domain numbers obtained from DT and pci_get_new_domain_nr(),
> + * which is a recipe for domain mishandling and it is prevented by
> + * invalidating the domain value (domain = -1) and printing a
> + * corresponding error.
> + */
> + if ( domain >= 0 && use_dt_domains )
> + {
> + use_dt_domains = 1;
> + }
> + else if ( domain < 0 && use_dt_domains != 1 )
> + {
> + use_dt_domains = 0;
> + domain = pci_get_new_domain_nr();
> + }
> + else
> + {
> + printk(XENLOG_ERR "Inconsistent \"linux,pci-domain\" property in
> DT\n");
> + BUG();
> + }
> +
> + return domain;
> +}
> +
> +int pci_host_common_probe(struct dt_device_node *dev,
> + int ecam_reg_idx)
> +{
> + struct pci_host_bridge *bridge;
> + struct pci_config_window *cfg;
> + int err;
> +
> + bridge = pci_alloc_host_bridge();
> + if ( !bridge )
> + return -ENOMEM;
> +
> + /* Parse and map our Configuration Space windows */
> + cfg = gen_pci_init(dev, ecam_reg_idx);
> + if ( !cfg )
> + {
> + err = -ENOMEM;
> + goto err_exit;
> + }
> +
> + bridge->dt_node = dev;
> + bridge->sysdata = cfg;
> + bridge->bus_start = cfg->busn_start;
> + bridge->bus_end = cfg->busn_end;
> +
> + bridge->segment = pci_bus_find_domain_nr(dev);
> +
> + pci_add_host_bridge(bridge);
> +
> + return 0;
> +
> +err_exit:
> + xfree(bridge);
> + return err;
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/arch/arm/pci/pci-host-generic.c
> b/xen/arch/arm/pci/pci-host-generic.c
> new file mode 100644
> index 0000000000..13d0f7f999
> --- /dev/null
> +++ b/xen/arch/arm/pci/pci-host-generic.c
> @@ -0,0 +1,55 @@
> +/*
> + * Copyright (C) 2021 Arm Ltd.
> + *
> + * Based on Linux drivers/pci/controller/pci-host-common.c
> + * Based on Linux drivers/pci/controller/pci-host-generic.c
> + * Copyright (C) 2014 ARM Limited Will Deacon <[email protected]>
> + *
> + * 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/>.
> + */
> +
> +#include <asm/device.h>
> +#include <xen/pci.h>
> +#include <asm/pci.h>
> +
> +static const struct dt_device_match gen_pci_dt_match[] = {
> + { .compatible = "pci-host-ecam-generic" },
> + { },
> +};
> +
> +static int gen_pci_dt_init(struct dt_device_node *dev, const void *data)
> +{
> + const struct dt_device_match *of_id;
> +
> + of_id = dt_match_node(gen_pci_dt_match, dev->dev.of_node);
> +
> + printk(XENLOG_INFO "Found PCI host bridge %s compatible:%s \n",
> + dt_node_full_name(dev), of_id->compatible);
> +
> + return pci_host_common_probe(dev, 0);
> +}
> +
> +DT_DEVICE_START(pci_gen, "PCI HOST GENERIC", DEVICE_PCI)
> +.dt_match = gen_pci_dt_match,
> +.init = gen_pci_dt_init,
> +DT_DEVICE_END
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * tab-width: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/include/asm-arm/pci.h b/xen/include/asm-arm/pci.h
> index 61e43da088..58a51e724e 100644
> --- a/xen/include/asm-arm/pci.h
> +++ b/xen/include/asm-arm/pci.h
> @@ -26,6 +26,34 @@ struct arch_pci_dev {
> struct device dev;
> };
>
> +/*
> + * struct to hold the mappings of a config space window. This
> + * is expected to be used as sysdata for PCI controllers that
> + * use ECAM.
> + */
> +struct pci_config_window {
> + paddr_t phys_addr;
> + paddr_t size;
> + uint8_t busn_start;
> + uint8_t busn_end;
> + void __iomem *win;
> +};
> +
> +/*
> + * struct to hold pci host bridge information
> + * for a PCI controller.
> + */
> +struct pci_host_bridge {
> + struct dt_device_node *dt_node; /* Pointer to the associated DT node */
> + struct list_head node; /* Node in list of host bridges */
> + uint16_t segment; /* Segment number */
> + u8 bus_start; /* Bus start of this bridge. */
> + u8 bus_end; /* Bus end of this bridge. */
> + void *sysdata; /* Pointer to the config space window*/
> +};
> +
> +int pci_host_common_probe(struct dt_device_node *dev,
> + int ecam_reg_idx);
> #else /*!CONFIG_HAS_PCI*/
>
> struct arch_pci_dev { };
> --
> 2.17.1
>
