Re: [PATCH v8 8/9] pci: Add support for creating a generic host_bridge from device tree

[Bjorn Helgaas]

On Tue, Jul 01, 2014 at 07:43:33PM +0100, Liviu Dudau wrote:
> Several platforms use a rather generic version of parsing
> the device tree to find the host bridge ranges. Move the common code
> into the generic PCI code and use it to create a pci_host_bridge
> structure that can be used by arch code.
> 
> Based on early attempts by Andrew Murray to unify the code.
> Used powerpc and microblaze PCI code as starting point.
> 
> Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
> Tested-by: Tanmay Inamdar <tinamdar@xxxxxxx>
> ---
>  drivers/of/of_pci.c       | 135 ++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/pci/host-bridge.c |  18 +++++++
>  include/linux/of_pci.h    |  10 ++++
>  include/linux/pci.h       |   8 +++
>  4 files changed, 171 insertions(+)
> 
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index 8481996..55d8320 100644
> --- a/drivers/of/of_pci.c
> +++ b/drivers/of/of_pci.c
> @@ -89,6 +89,141 @@ int of_pci_parse_bus_range(struct device_node *node, struct resource *res)
>  }
>  EXPORT_SYMBOL_GPL(of_pci_parse_bus_range);
>  
> +/**
> + * pci_host_bridge_of_get_ranges - Parse PCI host bridge resources from DT
> + * @dev: device node of the host bridge having the range property
> + * @resources: list where the range of resources will be added after DT parsing
> + * @io_base: pointer to a variable that will contain the physical address for
> + * the start of the I/O range.
> + *
> + * It is the callers job to free the @resources list if an error is returned.
> + *
> + * This function will parse the "ranges" property of a PCI host bridge device
> + * node and setup the resource mapping based on its content. It is expected
> + * that the property conforms with the Power ePAPR document.
> + *
> + * Each architecture is then offered the chance of applying their own
> + * filtering of pci_host_bridge_windows based on their own restrictions by
> + * calling pcibios_fixup_bridge_ranges(). The filtered list of windows
> + * can then be used when creating a pci_host_bridge structure.
> + */
> +static int pci_host_bridge_of_get_ranges(struct device_node *dev,
> +		struct list_head *resources, resource_size_t *io_base)
> +{
> +	struct resource *res;
> +	struct of_pci_range range;
> +	struct of_pci_range_parser parser;
> +	int err;
> +
> +	pr_info("PCI host bridge %s ranges:\n", dev->full_name);
> +
> +	/* Check for ranges property */
> +	err = of_pci_range_parser_init(&parser, dev);
> +	if (err)
> +		return err;
> +
> +	pr_debug("Parsing ranges property...\n");
> +	for_each_of_pci_range(&parser, &range) {
> +		/* Read next ranges element */
> +		pr_debug("pci_space: 0x%08x pci_addr:0x%016llx cpu_addr:0x%016llx size:0x%016llx\n",
> +			range.pci_space, range.pci_addr, range.cpu_addr, range.size);

If you're not trying to match other printk formats, you could try to match
the %pR format used elsewhere, e.g., "%#010llx-%#010llx" with
range.cpu_addr, range.cpu_addr + range.size - 1.

> +
> +		/*
> +		 * If we failed translation or got a zero-sized region
> +		 * then skip this range
> +		 */
> +		if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
> +			continue;
> +
> +		res = kzalloc(sizeof(struct resource), GFP_KERNEL);
> +		if (!res)
> +			return -ENOMEM;
> +
> +		err = of_pci_range_to_resource(&range, dev, res);
> +		if (err)
> +			return err;
> +
> +		if (resource_type(res) == IORESOURCE_IO)
> +			*io_base = range.cpu_addr;
> +
> +		pci_add_resource_offset(resources, res,
> +				res->start - range.pci_addr);
> +	}
> +
> +	/* Apply architecture specific fixups for the ranges */
> +	return pcibios_fixup_bridge_ranges(resources);
> +}
> +
> +static atomic_t domain_nr = ATOMIC_INIT(-1);
> +
> +/**
> + * of_create_pci_host_bridge - Create a PCI host bridge structure using
> + * information passed in the DT.
> + * @parent: device owning this host bridge
> + * @ops: pci_ops associated with the host controller
> + * @host_data: opaque data structure used by the host controller.
> + *
> + * returns a pointer to the newly created pci_host_bridge structure, or
> + * NULL if the call failed.
> + *
> + * This function will try to obtain the host bridge domain number by
> + * using of_alias_get_id() call with "pci-domain" as a stem. If that
> + * fails, a local allocator will be used that will put each host bridge
> + * in a new domain.
> + */
> +struct pci_host_bridge *
> +of_create_pci_host_bridge(struct device *parent, struct pci_ops *ops, void *host_data)
> +{
> +	int err, domain, busno;
> +	struct resource *bus_range;
> +	struct pci_bus *root_bus;
> +	struct pci_host_bridge *bridge;
> +	resource_size_t io_base;
> +	LIST_HEAD(res);
> +
> +	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
> +	if (!bus_range)
> +		return ERR_PTR(-ENOMEM);
> +
> +	domain = of_alias_get_id(parent->of_node, "pci-domain");
> +	if (domain == -ENODEV)
> +		domain = atomic_inc_return(&domain_nr);
> +
> +	err = of_pci_parse_bus_range(parent->of_node, bus_range);
> +	if (err) {
> +		dev_info(parent, "No bus range for %s, using default [0-255]\n",
> +			parent->of_node->full_name);
> +		bus_range->start = 0;
> +		bus_range->end = 255;
> +		bus_range->flags = IORESOURCE_BUS;

If you put the dev_info() down here, you can print &bus_range with %pR.

> +	}
> +	busno = bus_range->start;
> +	pci_add_resource(&res, bus_range);
> +
> +	/* now parse the rest of host bridge bus ranges */
> +	err = pci_host_bridge_of_get_ranges(parent->of_node, &res, &io_base);
> +	if (err)
> +		goto err_create;
> +
> +	/* then create the root bus */
> +	root_bus = pci_create_root_bus_in_domain(parent, domain, busno,
> +						ops, host_data, &res);
> +	if (IS_ERR(root_bus)) {
> +		err = PTR_ERR(root_bus);
> +		goto err_create;
> +	}
> +
> +	bridge = to_pci_host_bridge(root_bus->bridge);
> +	bridge->io_base = io_base;
> +
> +	return bridge;
> +
> +err_create:
> +	pci_free_resource_list(&res);
> +	return ERR_PTR(err);
> +}
> +EXPORT_SYMBOL_GPL(of_create_pci_host_bridge);
> +
>  #ifdef CONFIG_PCI_MSI
>  
>  static LIST_HEAD(of_pci_msi_chip_list);
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index 36c669e..cfee5d1 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -5,6 +5,9 @@
>  #include <linux/kernel.h>
>  #include <linux/pci.h>
>  #include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of_pci.h>
> +#include <linux/slab.h>
>  
>  #include "pci.h"
>  
> @@ -83,3 +86,18 @@ void pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res,
>  	res->end = region->end + offset;
>  }
>  EXPORT_SYMBOL(pcibios_bus_to_resource);
> +
> +/**
> + * Simple version of the platform specific code for filtering the list
> + * of resources obtained from the ranges declaration in DT.
> + *
> + * Platforms can override this function in order to impose stronger
> + * constraints onto the list of resources that a host bridge can use.
> + * The filtered list will then be used to create a root bus and associate
> + * it with the host bridge.
> + *
> + */
> +int __weak pcibios_fixup_bridge_ranges(struct list_head *resources)
> +{
> +	return 0;
> +}

I'd wait to add this until there's a platform that needs to implement it.
Splitting it out will make this patch that much smaller and easier to
understand.

> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> index dde3a4a..71e36d0 100644
> --- a/include/linux/of_pci.h
> +++ b/include/linux/of_pci.h
> @@ -15,6 +15,9 @@ struct device_node *of_pci_find_child_device(struct device_node *parent,
>  int of_pci_get_devfn(struct device_node *np);
>  int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
>  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
> +struct pci_host_bridge *of_create_pci_host_bridge(struct device *parent,
> +					struct pci_ops *ops, void *host_data);
> +
>  #else
>  static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
>  {
> @@ -43,6 +46,13 @@ of_pci_parse_bus_range(struct device_node *node, struct resource *res)
>  {
>  	return -EINVAL;
>  }
> +
> +static inline struct pci_host_bridge *
> +of_create_pci_host_bridge(struct device *parent, struct pci_ops *ops,
> +			void *host_data)
> +{
> +	return NULL;
> +}
>  #endif
>  
>  #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 7e7b939..556dc5f 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -402,6 +402,7 @@ struct pci_host_bridge {
>  	struct device dev;
>  	struct pci_bus *bus;		/* root bus */
>  	int domain_nr;
> +	resource_size_t io_base;	/* physical address for the start of I/O area */

I don't see where this is used yet.

As far as I know, there's nothing that prevents a host bridge from having
several I/O port apertures (or several memory-mapped I/O port spaces).

>  	struct list_head windows;	/* pci_host_bridge_windows */
>  	void (*release_fn)(struct pci_host_bridge *);
>  	void *release_data;
> @@ -1809,8 +1810,15 @@ static inline void pci_set_of_node(struct pci_dev *dev) { }
>  static inline void pci_release_of_node(struct pci_dev *dev) { }
>  static inline void pci_set_bus_of_node(struct pci_bus *bus) { }
>  static inline void pci_release_bus_of_node(struct pci_bus *bus) { }
> +
>  #endif  /* CONFIG_OF */
>  
> +/* Used by architecture code to apply any quirks to the list of
> + * pci_host_bridge resource ranges before they are being used
> + * by of_create_pci_host_bridge()
> + */
> +extern int pcibios_fixup_bridge_ranges(struct list_head *resources);
> +
>  #ifdef CONFIG_EEH
>  static inline struct eeh_dev *pci_dev_to_eeh_dev(struct pci_dev *pdev)
>  {
> -- 
> 2.0.0
> 
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