Re: [PATCH v2 3/9] PCI: Add generic function to probe PCI host controllers

From: Lorenzo Pieralisi
Date: Mon Jan 08 2018 - 09:32:14 EST


On Mon, Dec 18, 2017 at 07:16:03PM +0100, Cyrille Pitchen wrote:
> This patchs moves generic source code from
> drivers/pci/host/pci-host-common.c into drivers/pci/probe.c.
>
> Indeed the extracted lines of code were duplicated by many host
> controller drivers. Regrouping them into a generic function gives a
> change to properly share this code without introducing a useless
> dependency to PCI_HOST_COMMON, which selects PCI_ECAM when not needed by
> most host controller drivers.
>
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/pci/host/pci-host-common.c | 38 +++--------------------------
> drivers/pci/probe.c | 50 ++++++++++++++++++++++++++++++++++++++
> include/linux/pci.h | 3 +++
> 3 files changed, 57 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/pci/host/pci-host-common.c b/drivers/pci/host/pci-host-common.c
> index a613ea310e76..ba5d3dab5d89 100644
> --- a/drivers/pci/host/pci-host-common.c
> +++ b/drivers/pci/host/pci-host-common.c
> @@ -72,7 +72,6 @@ int pci_host_common_probe(struct platform_device *pdev,
> const char *type;
> struct device *dev = &pdev->dev;
> struct device_node *np = dev->of_node;
> - struct pci_bus *bus, *child;
> struct pci_host_bridge *bridge;
> struct pci_config_window *cfg;
> struct list_head resources;
> @@ -95,41 +94,12 @@ int pci_host_common_probe(struct platform_device *pdev,
> if (IS_ERR(cfg))
> return PTR_ERR(cfg);
>
> - /* Do not reassign resources if probe only */
> - if (!pci_has_flag(PCI_PROBE_ONLY))
> - pci_add_flags(PCI_REASSIGN_ALL_BUS);
> -
> - list_splice_init(&resources, &bridge->windows);
> - bridge->dev.parent = dev;
> - bridge->sysdata = cfg;
> - bridge->busnr = cfg->busr.start;
> - bridge->ops = &ops->pci_ops;
> - bridge->map_irq = of_irq_parse_and_map_pci;
> - bridge->swizzle_irq = pci_common_swizzle;

Hi Cyrille,

I appreciate the idea, I think though that the setting of
PCI_REASSIGN_ALL_BUS and the bridge hooks/members initialization should
be left to the host bridges probe routines, that was the reasoning
behind adding those hooks to struct pci_host_bridge in the first place.

You can create an OF wrapper that does call the resulting function (eg
of_pci_host_common_probe()) that sets the {map/swizzle}_irq() to the OF
version and then call pci_host_common_probe().

Lorenzo

> -
> - ret = pci_scan_root_bus_bridge(bridge);
> - if (ret < 0) {
> - dev_err(dev, "Scanning root bridge failed");
> + ret = pci_host_probe(bridge, dev, cfg->busr.start, &ops->pci_ops, cfg,
> + &resources);
> + if (ret) {
> + pci_free_resource_list(&resources);
> return ret;
> }
>
> - bus = bridge->bus;
> -
> - /*
> - * We insert PCI resources into the iomem_resource and
> - * ioport_resource trees in either pci_bus_claim_resources()
> - * or pci_bus_assign_resources().
> - */
> - if (pci_has_flag(PCI_PROBE_ONLY)) {
> - pci_bus_claim_resources(bus);
> - } else {
> - pci_bus_size_bridges(bus);
> - pci_bus_assign_resources(bus);
> -
> - list_for_each_entry(child, &bus->children, node)
> - pcie_bus_configure_settings(child);
> - }
> -
> - pci_bus_add_devices(bus);
> return 0;
> }
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 1360db508035..3dfdc579b7de 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2685,6 +2685,56 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> }
> EXPORT_SYMBOL_GPL(pci_create_root_bus);
>
> +int pci_host_probe(struct pci_host_bridge *bridge,
> + struct device *parent,
> + int busnr,
> + struct pci_ops *ops,
> + void *sysdata,
> + struct list_head *resources)
> +{
> + struct pci_bus *bus, *child;
> + int ret;
> +
> + /* Do not reassign resources if probe only */
> + if (!pci_has_flag(PCI_PROBE_ONLY))
> + pci_add_flags(PCI_REASSIGN_ALL_BUS);
> +
> + list_splice_init(resources, &bridge->windows);
> + bridge->dev.parent = parent;
> + bridge->sysdata = sysdata;
> + bridge->busnr = busnr;
> + bridge->ops = ops;
> + bridge->map_irq = of_irq_parse_and_map_pci;
> + bridge->swizzle_irq = pci_common_swizzle;
> +
> + ret = pci_scan_root_bus_bridge(bridge);
> + if (ret < 0) {
> + dev_err(parent, "Scanning root bridge failed");
> + return ret;
> + }
> +
> + bus = bridge->bus;
> +
> + /*
> + * We insert PCI resources into the iomem_resource and
> + * ioport_resource trees in either pci_bus_claim_resources()
> + * or pci_bus_assign_resources().
> + */
> + if (pci_has_flag(PCI_PROBE_ONLY)) {
> + pci_bus_claim_resources(bus);
> + } else {
> + pci_bus_size_bridges(bus);
> + pci_bus_assign_resources(bus);
> +
> + list_for_each_entry(child, &bus->children, node)
> + pcie_bus_configure_settings(child);
> + }
> +
> + pci_bus_add_devices(bus);
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(pci_host_probe);
> +
> int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
> {
> struct resource *res = &b->busn_res;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 11823f4f1d83..e76df07dac07 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -879,6 +879,9 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops, void *sysdata);
> struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> struct pci_ops *ops, void *sysdata,
> struct list_head *resources);
> +int pci_host_probe(struct pci_host_bridge *bridge, struct device *parent,
> + int busnr, struct pci_ops *ops, void *sysdata,
> + struct list_head *resources);
> int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
> int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
> void pci_bus_release_busn_res(struct pci_bus *b);
> --
> 2.11.0
>