of/pci: Add support for parsing PCI host bridge resources from DT

Provide a function to parse the PCI DT ranges that can be used to create a
pci_host_bridge structure together with its associated bus.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
[make io_base parameter optional]
Signed-off-by: Robert Richter <rrichter@cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Grant Likely <grant.likely@linaro.org>
CC: Rob Herring <robh+dt@kernel.org>
CC: Catalin Marinas <catalin.marinas@arm.com>

2 files changed, 123 insertions, 0 deletions

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 82d172fa145a..8882b467be95 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -1,7 +1,9 @@
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_pci.h>
+#include <linux/slab.h>
 
 static inline int __of_pci_pci_compare(struct device_node *node,
                                        unsigned int data)
@@ -114,6 +116,121 @@ int of_get_pci_domain_nr(struct device_node *node)
 }
 EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
 
+#if defined(CONFIG_OF_ADDRESS)
+/**
+ * of_pci_get_host_bridge_resources - Parse PCI host bridge resources from DT
+ * @dev: device node of the host bridge having the range property
+ * @busno: bus number associated with the bridge root bus
+ * @bus_max: maximum number of buses for this bridge
+ * @resources: list where the range of resources will be added after DT parsing
+ * @io_base: pointer to a variable that will contain on return the physical
+ * address for the start of the I/O range. Can be NULL if the caller doesn't
+ * expect IO ranges to be present in the device tree.
+ *
+ * It is the caller's job to free the @resources list.
+ *
+ * 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.
+ *
+ * It returns zero if the range parsing has been successful or a standard error
+ * value if it failed.
+ */
+int of_pci_get_host_bridge_resources(struct device_node *dev,
+                        unsigned char busno, unsigned char bus_max,
+                        struct list_head *resources, resource_size_t *io_base)
+{
+        struct resource *res;
+        struct resource *bus_range;
+        struct of_pci_range range;
+        struct of_pci_range_parser parser;
+        char range_type[4];
+        int err;
+
+        if (io_base)
+                *io_base = (resource_size_t)OF_BAD_ADDR;
+
+        bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
+        if (!bus_range)
+                return -ENOMEM;
+
+        pr_info("PCI host bridge %s ranges:\n", dev->full_name);
+
+        err = of_pci_parse_bus_range(dev, bus_range);
+        if (err) {
+                bus_range->start = busno;
+                bus_range->end = bus_max;
+                bus_range->flags = IORESOURCE_BUS;
+                pr_info("  No bus range found for %s, using %pR\n",
+                        dev->full_name, bus_range);
+        } else {
+                if (bus_range->end > bus_range->start + bus_max)
+                        bus_range->end = bus_range->start + bus_max;
+        }
+        pci_add_resource(resources, bus_range);
+
+        /* Check for ranges property */
+        err = of_pci_range_parser_init(&parser, dev);
+        if (err)
+                goto parse_failed;
+
+        pr_debug("Parsing ranges property...\n");
+        for_each_of_pci_range(&parser, &range) {
+                /* Read next ranges element */
+                if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_IO)
+                        snprintf(range_type, 4, " IO");
+                else if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_MEM)
+                        snprintf(range_type, 4, "MEM");
+                else
+                        snprintf(range_type, 4, "err");
+                pr_info("  %s %#010llx..%#010llx -> %#010llx\n", range_type,
+                        range.cpu_addr, range.cpu_addr + range.size - 1,
+                        range.pci_addr);
+
+                /*
+                 * 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 parse_failed;
+                }
+
+                err = of_pci_range_to_resource(&range, dev, res);
+                if (err)
+                        goto conversion_failed;
+
+                if (resource_type(res) == IORESOURCE_IO) {
+                        if (!io_base) {
+                                pr_err("I/O range found for %s. Please provide an io_base pointer to save CPU base address\n",
+                                        dev->full_name);
+                                err = -EINVAL;
+                                goto conversion_failed;
+                        }
+                        if (*io_base != (resource_size_t)OF_BAD_ADDR)
+                                pr_warn("More than one I/O resource converted for %s. CPU base address for old range lost!\n",
+                                        dev->full_name);
+                        *io_base = range.cpu_addr;
+                }
+
+                pci_add_resource_offset(resources, res, res->start - range.pci_addr);
+        }
+
+        return 0;
+
+conversion_failed:
+        kfree(res);
+parse_failed:
+        pci_free_resource_list(resources);
+        return err;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);
+#endif /* CONFIG_OF_ADDRESS */
+
 #ifdef CONFIG_PCI_MSI
 
 static LIST_HEAD(of_pci_msi_chip_list);
diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index 71062e9602f5..1fd207e7a847 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h
@@ -52,6 +52,12 @@ of_get_pci_domain_nr(struct device_node *node)
 }
 #endif
 
+#if defined(CONFIG_OF_ADDRESS)
+int of_pci_get_host_bridge_resources(struct device_node *dev,
+                        unsigned char busno, unsigned char bus_max,
+                        struct list_head *resources, resource_size_t *io_base);
+#endif
+
 #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)
 int of_pci_msi_chip_add(struct msi_chip *chip);
 void of_pci_msi_chip_remove(struct msi_chip *chip);