[PATCH v2 4/4] pci: Add support for creating a generic host_bridge from device tree
From: arnd@arndb.de (Arnd Bergmann)
Date: 2014-02-27 13:39:29
Also in:
linux-devicetree, linux-pci, lkml
On Thursday 27 February 2014 13:06:42 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@arm.com>
Please add Benjamin Herrenschmidt to Cc here, I think it would be helpful to get his input so we can make this work on powerpc as well.
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diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c index 06ace62..feb8436 100644 --- a/drivers/pci/host-bridge.c +++ b/drivers/pci/host-bridge.c@@ -6,9 +6,13 @@ #include <linux/init.h> #include <linux/pci.h> #include <linux/module.h> +#include <linux/of_address.h> +#include <linux/of_pci.h> #include "pci.h" +static int domain_nr; +
For correctness, I think you want an 'atomic_t' here and use atomic_inc_return() to get a new value.
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static struct pci_bus *find_pci_root_bus(struct pci_bus *bus) { while (bus->parent)@@ -91,3 +95,133 @@ void pcibios_bus_to_resource(struct pci_bus *bus, struct resource *res, res->end = region->end + offset; } EXPORT_SYMBOL(pcibios_bus_to_resource); + +/** + * 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. + * + * If this function returns an error then the @resources list will be freed. + * + * 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 ", + range.pci_space, range.pci_addr); + pr_debug("cpu_addr:0x%016llx size:0x%016llx\n", + range.cpu_addr, range.size); + + /* + * 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) { + err = -ENOMEM; + goto bridge_ranges_nomem; + } + + of_pci_range_to_resource(&range, dev, res); + + if (resource_type(res) == IORESOURCE_IO) + *io_base = range.cpu_addr; + + pci_add_resource_offset(resources, res, + res->start - range.pci_addr); + }
This is not the correct resource for I/O space at all. Please talk to Will, I've been over this with him in detail and he probably understands it now. I assume you are both working in the same building. Since this is common PCI code, you could also decide to open-code the pci_add_resource_offset() function. If you don't do that, I think you have a memory leak for the resources that you can avoid by allocating the resource and pci_host_bridge_window structures together with a single kzalloc.
+ /* Apply architecture specific fixups for the ranges */
+ pcibios_fixup_bridge_ranges(resources);
+
+ return 0;
+
+bridge_ranges_nomem:
+ pci_free_resource_list(resources);
+ return err;
+}
+
+/**
+ * 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);
+
+ domain = of_alias_get_id(parent->of_node, "pci-domain");
+ if (domain == -ENODEV)
+ domain = 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;
+ }
+ busno = bus_range.start;
+ pci_add_resource(&res, &bus_range);
+
+ /* now parse the rest of host bridge bus ranges */
+ if (pci_host_bridge_of_get_ranges(parent->of_node, &res, &io_base))
+ return NULL;
+
+ /* then create the root bus */
+ root_bus = pci_create_root_bus_in_domain(parent, domain, busno,
+ ops, host_data, &res);
+ if (!root_bus)
+ return NULL;Do we have any code that checks for conflicting domain/bus numbers here? I guess pci_create_root_bus_in_domain() will fail if you have that. Since pci_create_root_bus_in_domain() is a new function that you just introduced, it would be helpful to change the calling conventions so it returns an error pointer instead of NULL upon failing. of_create_pci_host_bridge() can do the same, but pci_create_root_bus() should keep returning NULL so we don't have to change all the callers.
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+ bridge = to_pci_host_bridge(root_bus->bridge); + bridge->io_base = io_base; + + return bridge; +} +EXPORT_SYMBOL_GPL(of_create_pci_host_bridge);diff --git a/include/linux/pci.h b/include/linux/pci.h index 1eed009..0c5e269 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h@@ -395,6 +395,7 @@ 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 */ struct list_head windows; /* pci_host_bridge_windows */ void (*release_fn)(struct pci_host_bridge *); void *release_data;
What is the io_base used for here?
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@@ -1786,11 +1787,23 @@ static inline struct device_node *pci_bus_to_OF_node(struct pci_bus *bus) return bus ? bus->dev.of_node : NULL; } +struct pci_host_bridge * +of_create_pci_host_bridge(struct device *parent, struct pci_ops *ops, + void *host_data); + +void pcibios_fixup_bridge_ranges(struct list_head *resources); #else /* CONFIG_OF */ 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) { } + +static inline struct pci_host_bridge * +pci_host_bridge_of_init(struct device *parent, struct pci_ops *ops, + void *host_data) +{ + return NULL; +} #endif /* CONFIG_OF */ #ifdef CONFIG_EEH